final report: gamma walkover and civil survey report
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FINAL REPORT
SDMS DocID 000201277
Gamma Walkover and Civil Survey
Shpack Landfill Superfund Site NortonAttleboro Massachusetts
Contract No DACW3399C0023
Prepared for
US Army Corps of Engineers New England District
Prepared by
Cabrera Services Inc 809 Main Street
East Hartford CT 06108
January 23 2001
t CABRERA SERVICES INC
809 Main Street bull East Hartford CT 06108 bull Phone (860) 289-1885 bull Fax (860) 289-2261 bull www cabreraservicescom
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
() OVERSIZED
(X) NON-PAPER MEDIA
0 OTHER
DESCRIPTION DOC 201277 Gamma Walkover and Civil Survey Data on Compact Disk
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
FINAL REPORT
Gamma Walkover and Civil Survey
Shpack Landfill Superfund Site NortonAttleboro Massachusetts
Contract No DACW3399C0023
Preparedor
US Army Corps of Engineers New England District
Prepared by
Cabrera Services Inc 809 Main Street
East Hartford CT 06108
January 232001
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations
AEC U S Atomic Energy Commission ALI Attleboro Landfill Inc CFR Code of Federal Regulations CPM Counts Per Minute CPR Cardio Pulmonary Resuscitation CRZ Contamination Reduction Zone DU Depleted Uranium El Enviroscapes Inc EPA United States Environmental Protection Agency ERM Environmental Resources Management EU Enriched Uranium EZ Exclusion Zone FIDLER Field Instrument for Detection of Low Energy Radiation FUSRAP Formerly Utilized Sites Remedial Action Program GPS Global Positioning System GWS Gamma Walkover Survey HPGe High Purity Germanium ISCR Initial Site Characterization Report ISOCS In Situ Object Counting System kV Kilovolt MDC Minimum Detectable Concentration MFC Massachusetts Plane Coordinate NAD North American Datum Nal Sodium Iodide NED New England District NEES New England Electric Service NIST National Institute for Standards and Technology NPL National Priorities List NORM Naturally Occurring Radioactive Material NRC U S Nuclear Regulatory Commission OSHA U S Occupational Safety and Health Administration PCig Pico curies per Gram PID Photo lonization Detector
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Acronyms and Abbreviations cont
QA Quality Assurance QC Quality Control QAPP Quality Assurance Project Plan RCOPC Radiological Contaminant of Potential Concern RIFS Remedial Investigation and Feasibility Study SOW Scope of Work SSHP Site Specific Health and Safety Plan SZ Support Zone USAGE United States Army Corps of Engineers V Volt
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10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
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of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
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() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
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DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
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(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
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DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
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AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
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() OVERSIZED
(X) NON-PAPER MEDIA
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DESCRIPTION DOC 201277 Gamma Walkover and Civil Survey Data on Compact Disk
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
FINAL REPORT
Gamma Walkover and Civil Survey
Shpack Landfill Superfund Site NortonAttleboro Massachusetts
Contract No DACW3399C0023
Preparedor
US Army Corps of Engineers New England District
Prepared by
Cabrera Services Inc 809 Main Street
East Hartford CT 06108
January 232001
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations
AEC U S Atomic Energy Commission ALI Attleboro Landfill Inc CFR Code of Federal Regulations CPM Counts Per Minute CPR Cardio Pulmonary Resuscitation CRZ Contamination Reduction Zone DU Depleted Uranium El Enviroscapes Inc EPA United States Environmental Protection Agency ERM Environmental Resources Management EU Enriched Uranium EZ Exclusion Zone FIDLER Field Instrument for Detection of Low Energy Radiation FUSRAP Formerly Utilized Sites Remedial Action Program GPS Global Positioning System GWS Gamma Walkover Survey HPGe High Purity Germanium ISCR Initial Site Characterization Report ISOCS In Situ Object Counting System kV Kilovolt MDC Minimum Detectable Concentration MFC Massachusetts Plane Coordinate NAD North American Datum Nal Sodium Iodide NED New England District NEES New England Electric Service NIST National Institute for Standards and Technology NPL National Priorities List NORM Naturally Occurring Radioactive Material NRC U S Nuclear Regulatory Commission OSHA U S Occupational Safety and Health Administration PCig Pico curies per Gram PID Photo lonization Detector
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations cont
QA Quality Assurance QC Quality Control QAPP Quality Assurance Project Plan RCOPC Radiological Contaminant of Potential Concern RIFS Remedial Investigation and Feasibility Study SOW Scope of Work SSHP Site Specific Health and Safety Plan SZ Support Zone USAGE United States Army Corps of Engineers V Volt
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
99023-1 CABRERA SERVICES INC Page 1 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
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Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
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Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
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FINAL REPORT
Gamma Walkover and Civil Survey
Shpack Landfill Superfund Site NortonAttleboro Massachusetts
Contract No DACW3399C0023
Preparedor
US Army Corps of Engineers New England District
Prepared by
Cabrera Services Inc 809 Main Street
East Hartford CT 06108
January 232001
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations
AEC U S Atomic Energy Commission ALI Attleboro Landfill Inc CFR Code of Federal Regulations CPM Counts Per Minute CPR Cardio Pulmonary Resuscitation CRZ Contamination Reduction Zone DU Depleted Uranium El Enviroscapes Inc EPA United States Environmental Protection Agency ERM Environmental Resources Management EU Enriched Uranium EZ Exclusion Zone FIDLER Field Instrument for Detection of Low Energy Radiation FUSRAP Formerly Utilized Sites Remedial Action Program GPS Global Positioning System GWS Gamma Walkover Survey HPGe High Purity Germanium ISCR Initial Site Characterization Report ISOCS In Situ Object Counting System kV Kilovolt MDC Minimum Detectable Concentration MFC Massachusetts Plane Coordinate NAD North American Datum Nal Sodium Iodide NED New England District NEES New England Electric Service NIST National Institute for Standards and Technology NPL National Priorities List NORM Naturally Occurring Radioactive Material NRC U S Nuclear Regulatory Commission OSHA U S Occupational Safety and Health Administration PCig Pico curies per Gram PID Photo lonization Detector
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Acronyms and Abbreviations cont
QA Quality Assurance QC Quality Control QAPP Quality Assurance Project Plan RCOPC Radiological Contaminant of Potential Concern RIFS Remedial Investigation and Feasibility Study SOW Scope of Work SSHP Site Specific Health and Safety Plan SZ Support Zone USAGE United States Army Corps of Engineers V Volt
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10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
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of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations
AEC U S Atomic Energy Commission ALI Attleboro Landfill Inc CFR Code of Federal Regulations CPM Counts Per Minute CPR Cardio Pulmonary Resuscitation CRZ Contamination Reduction Zone DU Depleted Uranium El Enviroscapes Inc EPA United States Environmental Protection Agency ERM Environmental Resources Management EU Enriched Uranium EZ Exclusion Zone FIDLER Field Instrument for Detection of Low Energy Radiation FUSRAP Formerly Utilized Sites Remedial Action Program GPS Global Positioning System GWS Gamma Walkover Survey HPGe High Purity Germanium ISCR Initial Site Characterization Report ISOCS In Situ Object Counting System kV Kilovolt MDC Minimum Detectable Concentration MFC Massachusetts Plane Coordinate NAD North American Datum Nal Sodium Iodide NED New England District NEES New England Electric Service NIST National Institute for Standards and Technology NPL National Priorities List NORM Naturally Occurring Radioactive Material NRC U S Nuclear Regulatory Commission OSHA U S Occupational Safety and Health Administration PCig Pico curies per Gram PID Photo lonization Detector
99023-1 CABRERA SERVICES INC Page iii
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations cont
QA Quality Assurance QC Quality Control QAPP Quality Assurance Project Plan RCOPC Radiological Contaminant of Potential Concern RIFS Remedial Investigation and Feasibility Study SOW Scope of Work SSHP Site Specific Health and Safety Plan SZ Support Zone USAGE United States Army Corps of Engineers V Volt
99023-1 CABRERA SERVICES INC Page iv
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
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of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Acronyms and Abbreviations cont
QA Quality Assurance QC Quality Control QAPP Quality Assurance Project Plan RCOPC Radiological Contaminant of Potential Concern RIFS Remedial Investigation and Feasibility Study SOW Scope of Work SSHP Site Specific Health and Safety Plan SZ Support Zone USAGE United States Army Corps of Engineers V Volt
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
99023-1 CABRERA SERVICES INC Page 21 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
99023-1 CABRERA SERVICES INC Page 22 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
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(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
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(X) OVERSIZED
() NON-PAPER MEDIA
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DESCRIPTION DOC 201277 Fidler Gamma Contour Map
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AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
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DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
10 INTRODUCTION
Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on the initial phase of a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-Cshy0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)
During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed fieldwork provides information to support planning for a full three-dimensional site characterization field effort currently being designed
This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed hi detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed hi this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination
11 Site Description and History
The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side
Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated hi the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west
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of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
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20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill
The town of Norton covers an area of 2982 square miles and has a population of 14260 with a population density of 497 people per square mile The town is host to 4852 housing units of which 3653 are single-family homes According to Mr Charles Gabriel Norton Town Planner during a telephone conversation on 121300 one new five-lot subdivision has currently been approved Also a proposal for a comprehensive permit has been submitted for 44 units off Maple Street but is still pending That site is planned for development in approximately three to four years The individual homes in the five-lot development off Maple Street are planned to include drinking water wells while the drinking water source for the 44-lot subdivision has not yet been determined
The town of Attleboro has a population of 38383 in an area of 2829 square miles yielding a population density of approximately 1395 people per square mile Census data from 1990 indicates that there are 15045 total housing units in Attleboro with 7846 of those single-family homes
The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981
On June 10 1986 the Site was listed on the National Priorities List (NPL) and the U S Environmental Protection Agency (EPA) signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed
At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115 kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable
99023-1 CABRERA SERVICES INC Page 2 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
99023-1 CABRERA SERVICES INC Page 3 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
99023-1 CABRERA SERVICES INC Page 5 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
99023-1 CABRERA SERVICES INC Page 6 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
20 FIELD ACTIVITIES AND METHODOLOGY
21 Objectives
The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological contaminants of potential concern (RCOPCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results indicate that radium and uranium of various enrichments were deposited hi relatively small discrete locations around the site and that widespread soil contamination is unlikely present The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides
22 Scope of Work
This field effort was carried out within a well-defined scope of work (SOW) SOW included the following
bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access
bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable
bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence
bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities
bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy
bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source
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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants
bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel
23 Health and Safety
Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections
231 Radiological Safety
Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following
bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed US Occupational Safety and Health Administration (OSHA) 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices
bull Personnel entering the Exclusion Zone (EZ) wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the EZ workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the EZ
bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working
bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring
bull Support Zone (SZ) areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
99023-1 CABRERA SERVICES INC Page 9 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
232 Industrial Safety
Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following
bull Entry to the EZ required safety shoes at all times
bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site
bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery
bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices
bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included
o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue
o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited
gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations
99023-1 CABRERA SERVICES INC Page 5 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
99023-1 CABRERA SERVICES INC Page 20 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
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Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
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Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues
bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that hi areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists were hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts hi protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six niches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions
24 Mobilization and Site Preparation
241 Site Mobilization
Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan
During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulins over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean SZ and was separated from the Contamination Reduction Zone (CRZ) and EZ using yellow and magenta ropes and postings to delineate the boundary accordingly The CRZ was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric
A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate
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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation
242 Site Clearing
The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan and vegetation was cut mulched and deposited in area where it was originally rooted Prior to project commencement CABRERAS Project Manager met with
_ _ bdquo bdquo _ the Conservation Director for Norton Figure6 1 Site Entrance Area Configuration J and discussed the clearing operations
During these discussions the Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas
CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel
El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
243 Civil Survey
During previous site work undertaken by Environmental Resources Management (ERM) Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System (MFC) North American Datum (NAD) 87 were verified
Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg
244 Repair of Perimeter Fence
During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 30 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 30-foot south end gap and repair the small holes in the frontage fence
During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However past chemical characterization results including those from the Initial Site Characterization Report (ISCR) (ERM 1993) revealed that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA to avoid interference with radiological survey schedules fence repairs were postponed until late in the fieldwork At that time however the high voltage lines had become a safety issue due to increased sag and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached
245 Site Radiological Posting
As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information
25 Gamma Walkover Survey
The GWS was carried out to provide an indication of the areal extent of elevated RCOPCs guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed
251 Instrumentation
Gamma detectors selected for this survey were chosen to provide gross detection of a broad spectrum of gamma energies The GWS was performed using a Ludlum Model 44-10 two inch by two inch sodium iodide (Nal) detector (44-10) and a Bicron Model G5 field instrument for detection of low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter with a lower level discriminator set just above electronic noise (ie open window) The FIDLER is sensitive to gammas from approximately 10 keV to greater than 100 keV while the 44-10 is sensitive to gammas from under 60 keV to in excess of 1000 keV This range of detectable gamma energies provided confidence that not only would suspected RCOPCs be detected but also other gamma emitting radionuclides that may have been disposed at the Site It should be noted that these detectors will only reliably detect gamma emitters located on or in close proximity to the land surface
The Model 2221 ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter
The FIDLER is fitted with a sensitive thin aluminum window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
detector response to the gamma energies of interest The Model G5 FIDLER probes (serial numbers B464V and B652V) were evaluated for the effect of a protective cover by comparing each detectors response to a depleted uranium slab source both with the cover in place and without the cover Detector response with the cover in place was reduced by approximately 17 for B464V and by approximately 16 for B652V
Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector
252 Ambient Gamma Reference Measurements and Quality Assurance
(A) Ambient Gamma Reference Measurements
Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain ambient gamma reference readings in a designated location area across Peckham Street from the Site It should be noted that daily ambient gamma reference values were not subtracted from GWS data but were obtained for qualitative comparison of day-toshyday ambient gamma fluctuations unrelated to Site contaminants During post-field data review the magnitude of daily ambient gamma fluctuations could prove an important input to GWS data analysis Excessive daily ambient gamma fluctuation might require adjustments to GWS data to normalize the data Daily ambient gamma reference measurements were also made and recorded for static and portable radiological support instruments but were assumed to represent instrument background and were used to estimate net instrument response (ie they were directly subtracted from instrument gross response)
(B) Daily Instrument Quality Control (QC)
Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie performed within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection
GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day
Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document
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253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
253 Survey Performance
The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions
(A) Data File Naming
Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where
bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)
bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER
bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)
bull zz is the code bk representing a ambient gamma reference measurement (ie background) survey file (eg the daily ambient gamma reference measurement survey file for the 44-10 on March 28 was named 032844bkssf)
bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger
(B) Survey Lines
To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)
bull Surveys proceeded along one-meter wide north-south paths beginning at the western comer of the site and proceeding to the east
bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags
bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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pound75 Army Corps of Engineers Gamma Walkover and Civil Survey Report
Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
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X
X
X
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X
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X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
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DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
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Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
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TARGET SHEET
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Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199
bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path
bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible
bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path
bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas sufficient GPS readings were obtained to automatically located GWS data
bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms
bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily
The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey
During GWS planning it was decided that no surveys would be performed over standing water due to the substantial shielding effects of water on gamma response During fieldwork however surveyors observed elevated count rates over areas covered by up to three inches of standing water As such a field decision was taken to record count rate data for all accessible site areas (defined as containing less than approximately 14 of standing water subject to safety concerns) A GPS unit was used to delineate all observed bodies of standing water for use in interpreting survey results The approximate edge of water is presented in the Appendix C gamma contour plots discussed in Section 31 to clarify the areas in which standing water was present While the project decision makers understood that standing water would cause substantial attenuation of gamma radiation it was decided that the qualitative value of collecting the data outweighed the limitations inherent in that data
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26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
99023-1 CABRERA SERVICES INC Page 21 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
99023-1 CABRERA SERVICES INC Page 22 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
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DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
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TARGET SHEET
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Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
26 ISOCS In situ Gamma Spectroscopy
ISOCS in situ high purity germanium (HPGe) gamma spectroscopy was used to estimate the activity concentration of gamma emitting radionuclides in site soils
261 Performance of Measurements
ISOCS measurements were performed in an un-collimated geometry (ie shielding was not utilized to limit the ISOCS field of view) The ISOCS HPGe detector was mounted on a surveyors tripod and positioned 05 meters above the measurement location facing downward such that the face of the detector was parallel to the ground surface Measurements performed in areas where elevated gamma count rates were observed were centered over the location where the highest count rate was noted in an effort to provide reasonably conservative results Typical count times were 10 minutes and accumulated spectra were stored for later analysis
262 ISOCS Efficiency Modeling
An essential component of the ISOCS measurement process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes
bull Area and depth of the contaminated soil (source term)
o Models used during this work assumed a soil volume with a diameter of 5 meters and a depth of 015 meters
bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)
o Models used during this work assumed that contaminants were uniformly distributed throughout the source term volume
bull Elemental composition of the source term and its density
o Models used during this work assumed that the source term was soil with a density of 16 gcc
bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector
o Models used during this work assumed cover thicknessess varying from 0 to 4 inches All covers were assumed to be composed of soil with a density of 16 gcc Lateral dimensions of covers were assumed to be infinite The assumed cover thicknesses were based on observed ISOCS data as described in 2 below
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This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
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30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
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X
X
X
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X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of each detected radionuclide in the source term
The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows
1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations
2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)
99023-1 CABRERA SERVICES INC Page 14 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
99023-1 CABRERA SERVICES INC Page 15 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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pound75 Army Corps of Engineers Gamma Walkover and Civil Survey Report
Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
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DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
30 SURVEY RESULTS
31 Data Handling and Quality Assurance
Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 were processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data were collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded hi the Project Data Logbook
Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report
Prior to posting gamma data to the contour maps the data were reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than the ambient level In cases where disqualified data was of a significant magnitude (ie gt 10000 cpm for the 44-10 and gt 15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding pouits or by extrapolation from neighboring points In cases where the data were not of significant magnitude no qualification efforts were made
Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified Such data spikes result from energizing the gamma detector after GPS logging has begun This spike is readily apparent when inspecting data posted as contours The variation is of such a magnitude as to be obvious for example hi an area of approximately 7000 to 10000 counts per minute (cpm) a single data point hi excess of 900000 cpm would be recorded It is this type of single data point that was disqualified It should be noted that while performing the GWS since a large number of count rate data are recorded per unit area variations hi count rate occur hi relatively small steps Even upon encountering a small localized area of very elevated activity the data trends up hi incremental steps As such the data spikes discussed above are easily discerned during data analysis since they have no surrounding data supporting the expected trending pattern In cases where even slight trends
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surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
surround apparent spikes the spike would be treated as a valid reading In addition follow up measurements were performed at the locations where data spikes were disqualified Results of these measurements confirmed that the initial readings were erroneous
Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer
All data review and QA methodologies and actions were recorded in the Project Data Logbook
32 GWS Survey Results
As can be seen in the gamma data contour plots in Appendix C assumptions regarding the distribution of near surface radiological contaminants at the Site discussed in Section 21 appear to be valid Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm
Examination of ambient gamma reference data revealed that daily variation was minimal For the FIDLER the relative standard deviation of daily average ambient gamma reference values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily average ambient gamma reference values was approximately 073 or 73 As such no adjustment to GWS data was required
An examination of the survey data reveals that as anticipated count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 urhr in grid 2224 and approximately 900 urhr in grids 10991100 This compared to ambient levels of approximately 6-12 urhr in other site areas
Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed mat the FIDLER showed better sensitivity overall than the 44-10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect
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Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
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(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
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DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
pound75 Army Corps of Engineers Gamma Walkover and Civil Survey Report
Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report
33 ISOCS Survey Results
ISOCS in situ gamma spectroscopy results are summarized on Table 1
331 Uranium Results
Uranium ranging in U-235 mass enrichment from depleted to fully enriched was identified as a RCOPC during previous investigative activities at the site Three different uranium isotopes typically predominate hi uranium contamination U-234 U-235 and U-238 Quantification of U-238 was based on measurements of Pa-234m via its 1001 keV gamma line quantification of U-235 was based on direct measurements of its 143 keV gamma line Gamma spectroscopy techniques such as those employed by ISOCS are sensitive to U-235 and U-238 but are relatively insensitive to U-234 which is typically analyzed in a laboratory using alpha spectroscopy analysis However U-234 concentration can be inferred from measured U-235 and U-238 concentrations based on isotopic activity fractions which vary with U-235 mass enrichment Table 1 lists the mass and activity fractions of each these uranium isotopes for varying uranium enrichments
Table 1
Isotopic Uranium Components for Uranium of Varying Enrichments
Uranium Type (1) Mass Percentage Activity Percentage
U-234 U-235 U-238 U-234 U-235 U-238
Depleted Uranium 0001 02 998 142 110 847
Natural Uranium 001 071 993 489 220 489
Low Enriched Uranium 0029 35 965 818 340 147
Fully Enriched Uranium 106 934 558 970 297 0028
(l) Assumed U-235 mass enrichments are shown as the mass percentage of U-235
Some of the properties of depleted natural and enriched uranium are summarized below
bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution
bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution
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bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
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bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass) U-238 comprises the majority of the remainder of the mass U-234 is also present but represents a small to negligible mass contribution
bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration
bull On an activity basis depleted uranium is primarily comprised of U-238 U-234 comprises approximately 15 of the activity
bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present
Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is greater than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely hi excess of background Consequently any positive detections of U-235 are considered elevated concentrations
Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)
Of the 97 measurements only 15 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium A summary of U-235 concentrations greater than 5 pCig follows
bull One measurement out of two in grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17
bull Two measurements out of four in grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)
bull Two measurements out of four in grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)
99023-1 CABRERA SERVICES INC Page 18 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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TARGET SHEET
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DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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TARGET SHEET
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DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
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TARGET SHEET
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DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
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Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull The only measurement in grid 1098 and one out of two measurements in adjacent grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC5 pCig and greater than 388 enrichment) pCig respectively
bull Elevated U-235 concentrations were observed in one out of two measurements hi grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) -and two out of two measurements hi adjacent grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)
bull One out of two measurements hi grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)
bull One out of two measurements in grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)
bull Two out of three measurements in grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)
bull Three out of three measurements in grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)
bull The only measurement hi grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)
bull The only measurement hi grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)
bull One out of two measurements hi grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)
bull The only measurement in grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)
bull The only measurement in grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)
bull The only measurement in grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)
bull The only measurement in grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)
bull The only measurement hi grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull Five out of five measurements in grid 1273 one out of one in grid 1274 four out of four in grid 1278 and one out of one in grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1
Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig
bull The only measurement in grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)
bull One of two measurements in grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)
bull One of two measurements in grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)
bull One of two measurements in grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)
bull One of three measurements in grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)
bull The only measurement in grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)
bull The only measurement in grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)
bull One of two measurements in grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)
332 Radium-226 Results
Radium-226 was identified as a RCOPC during previous investigative activities at the site Under controlled conditions Ra-226 will be in secular equilibrium with its short-lived radioactive decay products (ie down through but not including Pb-210) However in the environment Radon-222 (Rn-222) which is a noble gas and the direct decay product of Rashy226 will likely diffuse from the soil resulting in disequilibrium between Ra-226 and its short-lived decay products
Ra-226 ISOCS results are based on quantification of Bismuth-214 (Bi-214) primarily via its 609 keV gamma line Bi-214 is a short-lived decay product of Ra-226 and as stated previously may not be in equilibrium with Ra-226 Thus reported Ra-226 results could be higher or lower than actual surface soil concentrations Disequilibrium would likely result in
99023-1 CABRERA SERVICES INC Page 20 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
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US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
underestimation of Ra-226 but could also result in overestimation especially if there are substantial quantities of subsurface Ra-226
Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226-virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination
Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull The only measurement hi grid 1035 and the only measurement hi adjacent grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively
bull The only measurement in grid 1038 exhibited a Ra-226 concentration of 244 pCig
bull The only measurement in grid 1043 and two out of two measurements hi adjacent grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig
bull One out two measurements hi grid 1056 exhibited a Ra-226 concentration of 292 pCig
bull The only measurement hi grid 1063 exhibited a Ra-226 concentration of 143 pCig
bull One out of three measurements hi grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements hi adjacent grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig
bull Two out of four measurements hi grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig
bull One out of two measurements in grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements hi adjacent grid 1132 exhibited a Ra-226 concentration of 219 pCig
bull Three out of three measurements hi grid 1157 the only measurement in adjacent grid 1158 three out of three measurements in adjacent grid 1164 and the only measurement hi adjacent grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig
bull Two measurements out of two hi grid 1223 and two measurements out of three hi grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig
bull The only measurement in grid 1237 exhibited a Ra-226 concentration of 589 pCig
99023-1 CABRERA SERVICES INC Page 21 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
99023-1 CABRERA SERVICES INC Page 22 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
bull One measurement out of five in grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in grid 1278 which is adjacent to grid 1273 exhibited a Rashy226 concentration of 273 pCig The only measurement in grid 1279 which is adjacent to grid 1278 exhibited a Ra-226 concentration of 340 pCig
bull The only measurement in grid 1281 exhibited a Ra-226 concentration of 161 pCig
333 Thorium-232 Results
Uranium and Radium-226 were identified as the RCOPCs during previous investigative activities at the site However at some locations elevated concentrations of Pb-212 a Th-232 decay product were also identified quantification of Pb-212 was primarily based on its 239 keV gamma line The presence of elevated concentrations of Pb-212 could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of elevated Th-232
Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232
However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 As such Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected
Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)
bull One measurement out of four in grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
bull One measurement out of two in grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 219 pCig indicates that some or all of this concentration may be due to the presence of Ra-228
99023-1 CABRERA SERVICES INC Page 22 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
One measurement out of two in grid 1225 and the only measurement in grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model
bull One measurement in two in grid 1249 close to the Border of grid 1273 five out of five measurements in grid 1273 and two out of four measurements in grid 1278 close to the border of grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in grid 1273 and one measurement in grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in grid 1273 possibly some type of a furnace (Figure 2) Figure 2 Brick-filled Metal ObjectThe majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain relatively high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it may also be due the presence ofRa-228
34 Correlation of Portable Instrument Response to ISOCS Data
One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation
Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different RCOPCs because they exist in different proportions to each other throughout the site
In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the
99023-1 CABRERA SERVICES INC Page 23 of 3 8
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2
Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero
FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10
FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium
The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all RCOPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations
The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig
It should be noted that the presence of a clean cover over the RCOPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination
99023-1 CABRERA SERVICES INC Page 24 of 38
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
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CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
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99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
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Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
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E
8
T3 (0
Q^ (0
ltgt
gtO
a
I O O
palt U
o pound
(N
o
s CM
II
UU
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(NO
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o
I1
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ooo
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8o
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bull
Q
CO p oo o
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oc oo
ltpoundgt
8shy oooom
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0gt y(A Ift gt ce o
o8
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(gt
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CN
O s
o10 CO CO CN CN
paa|d8Q
O ON
o
I
1
sI
I
oo
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Ia gt
o
o R
om
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coo D
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tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
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0)2 o
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i CO
oo
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ugt 00
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pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
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ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
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1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
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pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
s S S S S S 8 S S s iS CM CM o
bullH bullH
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poundCO oo co CO in ~raquo CO CM CO ce a
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amp 0 CO en 0 CO a s -CO CM CO i o d d d dQ
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ltA 1 S I1 i fshy 1 CM o nN 03 en in in CM CM CM CO CO S
3 ca S o sect
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amp 10 CM trade UJ clt CO CM 01 CM 8 83 HCM CO co CO II
Q a to i ^O HI z z a f= D z
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8547815
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8548088
1 2220833
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8548168
1 2221210
8548489
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bull
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oc oo
ltpoundgt
8shy oooom
Q ^O
0gt y(A Ift gt ce o
o8
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(gt
ltU
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CN
O s
o10 CO CO CN CN
paa|d8Q
O ON
o
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Ia gt
o
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om
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aI
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S0 1 I
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I I to 1 8
o 8 bull5c
coo D
CM
tf) 0)tngt 0)i w
tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
E
CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
1o o CM SCO CO
hshy
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CO
CO
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CO
Q IO CO
(O(O10
^1 0gt
32
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I
re pound1 O o
OO
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a 0gt
o
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CO
(iudo) )unoo SSOJQ
ugt 00
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(0 laquoA 2 a
I
I (0 CO
E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
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a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Ied
U-2
35
1
5$ 8 oin O
00 to d ^ ^ a CM in CM o o o
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poundCO oo co CO in ~raquo CO CM CO ce a
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in N N i s f( CM pound o K ir cc CM d
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3
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^ (0 S d d d d O
^UJ CO K CO (0 o8
CM
oCM
a a S sCM d d d d d3 V) oO
K a Q CM CO CM CO CO d d o d o
CO Q 03 o CO
g o i d o d d o d
CM J
in bull iTl C S u ltO
o 8 o oCM CM d o o d laquo lillCO a 3
amp 0 CO en 0 CO a s -CO CM CO i o d d d dQ
s
FID
LE
R
I
180
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8 oo oo bullshy
r- oo oo Io secto
1i oo a
GN
S R
e
2200
00
3 aCM
X a CM 1
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1m oo o o Vshy
gt bullcbull 81O u g
bullH
Ass
um
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nocove
no c
ove
no
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no
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catio
n ID
ltA 1 S I1 i fshy 1 CM o nN 03 en in in CM CM CM CO CO S
3 ca S o sect
1 CM o 0
Num
ber
amp 10 CM trade UJ clt CO CM 01 CM 8 83 HCM CO co CO II
Q a to i ^O HI z z a f= D z
I IS c bullg
= 5 s r s s
Northin
g
g
I 2220723
8547815
| 2220729
8548088
1 2220833
8548260
I 2220848
8548168
1 2221210
8548489
1 2221263
8547729
| 2221309
8548079
at c
n IO Ul
02
I oo
deglt ON ltN
88
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ij
CO
CO 8
8
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8
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Q^ (0
ltgt
gtO
a
I O O
palt U
o pound
(N
o
s CM
II
UU
i
(NO
O
o
I1
o CD
ooo
O
8o
sectCN
bull
Q
CO p oo o
ooo0)
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oc oo
ltpoundgt
8shy oooom
Q ^O
0gt y(A Ift gt ce o
o8
O (ACO
(gt
ltU
o ce CQ(A
CN
O s
o10 CO CO CN CN
paa|d8Q
O ON
o
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1
sI
I
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Ia gt
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om
oo
om
aI
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S0 1 I
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I I to 1 8
o 8 bull5c
coo D
CM
tf) 0)tngt 0)i w
tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
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CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
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hshy
ltD CD
CO
CO
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Q IO CO
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32
z CO CO
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re pound1 O o
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a 0gt
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oo
CO
(iudo) )unoo SSOJQ
ugt 00
ogt
(0 laquoA 2 a
I
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E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
I oo
deglt ON ltN
88
G
ij
CO
CO 8
8
0)O
I 2
OO
E
8
T3 (0
Q^ (0
ltgt
gtO
a
I O O
palt U
o pound
(N
o
s CM
II
UU
i
(NO
O
o
I1
o CD
ooo
O
8o
sectCN
bull
Q
CO p oo o
ooo0)
D
oc oo
ltpoundgt
8shy oooom
Q ^O
0gt y(A Ift gt ce o
o8
O (ACO
(gt
ltU
o ce CQ(A
CN
O s
o10 CO CO CN CN
paa|d8Q
O ON
o
I
1
sI
I
oo
0)E
3
Ia gt
o
o R
om
oo
om
aI
I
I
1raquo-bull
S0 1 I
1
8
Q S
I I to 1 8
o 8 bull5c
coo D
CM
tf) 0)tngt 0)i w
tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
E
CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
1o o CM SCO CO
hshy
ltD CD
CO
CO
E1E
I O)
CO CO Cl
O)O)oo
CO
Q IO CO
(O(O10
^1 0gt
32
z CO CO
I
re pound1 O o
OO
o Q (0
a 0gt
o
oo
CO
(iudo) )unoo SSOJQ
ugt 00
ogt
(0 laquoA 2 a
I
I (0 CO
E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
O
o
I1
o CD
ooo
O
8o
sectCN
bull
Q
CO p oo o
ooo0)
D
oc oo
ltpoundgt
8shy oooom
Q ^O
0gt y(A Ift gt ce o
o8
O (ACO
(gt
ltU
o ce CQ(A
CN
O s
o10 CO CO CN CN
paa|d8Q
O ON
o
I
1
sI
I
oo
0)E
3
Ia gt
o
o R
om
oo
om
aI
I
I
1raquo-bull
S0 1 I
1
8
Q S
I I to 1 8
o 8 bull5c
coo D
CM
tf) 0)tngt 0)i w
tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
E
CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
1o o CM SCO CO
hshy
ltD CD
CO
CO
E1E
I O)
CO CO Cl
O)O)oo
CO
Q IO CO
(O(O10
^1 0gt
32
z CO CO
I
re pound1 O o
OO
o Q (0
a 0gt
o
oo
CO
(iudo) )unoo SSOJQ
ugt 00
ogt
(0 laquoA 2 a
I
I (0 CO
E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
1raquo-bull
S0 1 I
1
8
Q S
I I to 1 8
o 8 bull5c
coo D
CM
tf) 0)tngt 0)i w
tn co 00
IQ ()
8 opound
- 8 CM
S o o8 8 8 o oo r^ CD CM
wmuejn paqouug
r
i
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
E
CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
1o o CM SCO CO
hshy
ltD CD
CO
CO
E1E
I O)
CO CO Cl
O)O)oo
CO
Q IO CO
(O(O10
^1 0gt
32
z CO CO
I
re pound1 O o
OO
o Q (0
a 0gt
o
oo
CO
(iudo) )unoo SSOJQ
ugt 00
ogt
(0 laquoA 2 a
I
I (0 CO
E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
US Army Corps cf Engineers Gamma Walkover and Civil Survey Report
Table 3
Locations Selectedfor Instrument Response Evaluation
Map Number
49 90 52 65 57 94 95 85 62 56 50 3 7 4 6
77 27 13 37 33 19 16 11 17 14 34
Location ID
1043sw 1063sw 1087nw 1088ne 1088se 1096se 1096sw 1131sw 1157se
1164sw 1165ne 1174se 1205ne 1205se 1214ne
1225se(3) 1236se 1249se 1254sw 1270nw 1273nw
1273se(2) 1273sw 1278se 1278sw 1298sw
Selected Locations Radium EU DU
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CABRERA SERVICES INC Page 32 of 38 99023-1
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
40 CURRENT SITE STATUS
Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric service was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the EZ were collected bagged andor drummed and placed in the shed located hi the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary
99023-1 CABRERA SERVICES INC Page 33 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 34 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
50 CONCLUSIONS
The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally considering that if the contamination was spreading the variability in elevated count rates would likely exhibit a greater spatial gradient Several areas of the site were covered with water and could not be safely surveyed and hi some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site
The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2)
Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities
Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of RCOPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these RCOPCs using field instruments will be difficult This sensitivity difference can be compensated hi the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference hi clean up criteria between the RCOPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans
In general the results of this survey were consistent with past evaluations with the exception that Th-232 decay products were identified by in situ gamma spectroscopy in some locations The elevated Th-232 decay products are suspected to result from the presence of firebrick which is assumed to have a high naturally occurring Th-232 content This will be confirmed during subsequent characterization phases as soil samples will be collected in the area where the Th-232 was identified to characterize uranium in that area the results of these samples will quantify Th-232 In addition samples of the firebrick will also be collected and analyzed
99023-1 CABRERA SERVICES INC Page 35 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
to support ultimate disposal of the firebrick It should be noted that this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase
99023-1 CABRERA SERVICES INC Page 36 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
60 REFERENCES
CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack LandfillSite Cabrera Services Inc December 301999
Superfund
CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill SuperfundCabrera Services Inc December 301999
Site
CABRERA 1999c Quality Assurance Project Plan Shpack LandfillServices Inc December 301999
Superfund Site Cabrera
CABRERA 1999d Records SearchSite Walkover Report Shpack LandfillCabrera Services Inc August 1999
Superfund Site
CABRERA 1999e TechnicalMemorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999
ERM 1993 Initial Site Characterization Report Shpack Landfill SuperfundNew England March 171993
Site ERM
Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991
OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 311994
USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997
USAGE 1997b Engineering Regulation ER-385-1-80 Radiation SafetyArmy Corps of Engineers May 301997
United States
99023-1 CABRERA SERVICES INC Page 37 of 38
US Army Corps of Engineers Gamma Walkover and Civil Survey Report
This page intentionally left blank
99023-1 CABRERA SERVICES INC Page 38 of 38
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Civil Survey Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix A
Civil Survey Map
Appendix B Instrument Control
Charts
OJ
o j_ re 03 T3 E re re D
poundE E 3) O) O) CO p 0gt CT) T5 CO CO bco co 5 o oA CO t fl O Edeg ^ lt
1 i 0 1 i +
i bull
2 8 o
2 o m
rabullc Qra
O
1+bullbull O O O w o QW
0)2 o
jnOlUJ3JOJ3jUl 9SOQ
05 0gt
E
CO O) V ^ w
Ogt w Sogt
0 sect deg
O)PO CM 00 IO
(0 0)pound 2 o 9
i ogt
CM Ogt
(0 CO
E
pound
re O
o O 0)(0
o Q 0)0)o 0)if 3 O (0
(iudo) junoo SSOJQ
i CO
oo
1o o CM SCO CO
hshy
ltD CD
CO
CO
E1E
I O)
CO CO Cl
O)O)oo
CO
Q IO CO
(O(O10
^1 0gt
32
z CO CO
I
re pound1 O o
OO
o Q (0
a 0gt
o
oo
CO
(iudo) )unoo SSOJQ
ugt 00
ogt
(0 laquoA 2 a
I
I (0 CO
E
pound bullc re O
1+bullgt o o o (0
o Q(0
agt 2 o
sectiS
CO O IIS CO
D) O) |co 2lt0 rn rn co CO 0) CO CO bdquo gt CM CO CM CM 00deg ^ ltC + + +
f i lt_)
(uido) ajey junoo SSOJQ
c3 o
01 intn o vL_ _
O TO
N- Mo E g raquo E E O)
ipound ogt 1 pound 45 W ^ 5 co w o aP lt0 -~ CO CN 0
CO o0 ^ ltC yen 7 0
i i +5 i i1
i
1 (O
(uido) ajey unoo SSOJQ
co
(iudo) SSOJQ
(tudo) ajey junoo aojnos eqdiv SSOJQ
mdash bullpound w eco CM CM (N 3 +
o
(ludo) )unoo ejag SSOJQ
(wdo) ejey )unoo eojnos eqdiv SSOJQ
s-1
37 G
ross
Cou
ntat
e (c
pm)
5 S
igm
a
2 S
igm
a 03 CO 1) C C
=bull =gt ^ ^c 5 W W g S gt CM CO CM S
C_) Q_ 1 i lt( + + + r
1 1 i
(iudo) junoo SSOJQ
Appendix C Gamma Survey Result
Contour Plots
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Gamma Survey Results Contour Plots
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 Fidler Gamma Contour Map
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
Appendix D ISOCS Locations and
FIDLER Gamma Contour Plot
TARGET SHEET
THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE
(X) OVERSIZED
() NON-PAPER MEDIA
() OTHER
DESCRIPTION DOC 201277 ISOCS Locations and Fidler Gamma Contour Plot
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT
AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA
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