table of contents page · 9/8/2005 · • task 3: monitoring well redevelopment • task 4:...

TABLE OF CONTENTS

Page EXECUTIVE SUMMARY........................................................................................................... i

1.0 INTRODUCTION.............................................................................................................1 1.1 SITE DESCRIPTION AND HISTORY............................................................................2 1.2 SITE INVESTIGATIONS CONDUCTED PRIOR TO THE RI.............................................3

1.2.1 ERM and Eder Investigations (1992-1993)...............................................3 1.2.2 CRA Investigation (1996) .........................................................................4

1.2.2.1 Objectives and Scope of Work ......................................................4 1.2.2.2 CRA Investigation Results ............................................................5

1.2.3 Preaquisition Soils Investigation ...............................................................8 1.2.3.1 Scope of Work...............................................................................8 1.2.3.2 Results and Conclusions................................................................9

1.2.4 NYSDEC Preliminary Site Assessment Report Glen Head Groundwater Plume (September 2000) .....................................................9

2.0 REMEDIAL INVESTIGATION SCOPE OF WORK AND METHODS......................10 2.1 RI OBJECTIVES .....................................................................................................10 2.2 RI SAMPLING RATIONALE .....................................................................................10 2.3 REMEDIAL INVESTIGATION TASKS .......................................................................11

2.3.1 Task 1: Soil Boring Program...................................................................12 2.3.2 Task 2: Surface Soil Sampling ................................................................13 2.3.3 Task 3: Monitoring Well Redevelopment ...............................................13 2.3.4 Task 4: Hydraulic Head Monitoring........................................................14 2.3.5 Task 5: Groundwater Sampling and Analyses ........................................14 2.3.6 Task 6: Background Soil Sampling.........................................................15 2.3.7 Task 7: Soil Vapor Screening and Sampling...........................................15

2.4 IRM INVESTIGATION SAMPLING PROGRAM .........................................................16 2.4.1 IRM Objective and Scope .......................................................................16 2.4.2 IRM Soil Borings ....................................................................................16 2.4.3 IRM Subsurface Structure Sampling.......................................................17

2.5 RI QUALITY ASSURANCE/QUALITY CONTROL MEASURES......................................17 2.6 SUPPLEMENTAL RI ...............................................................................................18

2.6.1 Supplemental RI Task 1: Supplemental Surface Soil Sampling .............19 2.6.2 Supplemental RI Task 2: Building A Investigations ...............................19

2.6.2.1 Building A Ambient Indoor Air ..................................................19 2.6.2.2 Building A Ambient Outdoor Air................................................20 2.6.2.3 Building A Subsurface Soil and Soil Vapor Sampling ...............20 2.6.2.4 Building A Septic System Investigation......................................21

2.6.3 Supplemental RI Task 3: Supplemental Cesspool Sampling ..................21 2.6.4 Supplemental RI Task 4: Soil Vapor Sampling-South Portion of Site ...22

3.0 LAND USE AND PHYSICAL CONDITIONS OF THE SITE .....................................23 3.1 POPULATION DATA................................................................................................23 3.2 SITE PHYSIOGRAPHY AND CLIMATE.......................................................................23

TABLE OF CONTENTS (Continued)

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3.2.1 Site Physiography....................................................................................23 3.2.2 Climate ....................................................................................................23

3.3 WATER SUPPLY ....................................................................................................24 3.4 SURFACE WATER...................................................................................................24

3.4.1 Storm Water.............................................................................................24 3.4.2 Floodplain Areas .....................................................................................24

4.0 GEOLOGY AND HYDROGEOLOGY..........................................................................25 4.1 REGIONAL GEOLOGY AND HYDROLOGY...............................................................25

4.1.1 Pleistocene Deposits (Upper Glacial Unit)..............................................25 4.1.2 Magothy Formation .................................................................................25 4.1.3 Raritan Formation....................................................................................26

4.1.3.1 Unnamed Clay Member ..............................................................26 4.1.3.2 Lloyd Sand Member ....................................................................26

4.1.4 Regional Groundwater Flow ...................................................................26 4.2 SITE GEOLOGY AND HYDROGEOLOGY ...................................................................27

5.0 CHEMICAL PRESENCE IN SITE MEDIA ..................................................................29 5.1 SOILS....................................................................................................................29

5.1.1 Background Surface Soil .........................................................................29 5.1.2 Site Surface Soil ......................................................................................30

5.1.2.1 Remedial Investigation Results ...................................................30 5.1.2.2 Supplemental Remedial Investigation Results ............................31

5.1.3 Subsurface Soil ........................................................................................31 5.1.3.1 Remedial Investigation Results ...................................................31 5.1.3.2 Supplemental Remedial Investigation Results ............................32

5.2 SOIL VAPOR .........................................................................................................32 5.2.1 Remedial Investigation Results ...............................................................32 5.2.2 Supplemental Remedial Investigation Results ........................................33

5.3 SUBSURFACE DRAINAGE STRUCTURES.................................................................34 5.3.1 IRM Investigation Sampling Program.....................................................34 5.3.2 Supplemental Remedial Investigation.....................................................35

5.3.2.1 Cesspool C-2 and Cesspool West of Building C.........................35 5.3.2.2 Building A Septic System ...........................................................36

5.4 AMBIENT AIR (BUILDING A) ................................................................................36 5.5 GROUNDWATER....................................................................................................37

5.5.1 Upper Zone Groundwater........................................................................37 5.5.2 Lower Zone Groundwater .......................................................................38

6.0 QUALITATIVE HUMAN HEALTH EXPOSURE ASSESSMENT.............................39 6.1 POTENTIAL CHEMICAL TRANSPORT PATHWAYS...................................................39

6.1.1 Airborne Pathways ..................................................................................39 6.1.1.1 Fugitive Dust ...............................................................................39


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6.1.1.2 Volatilization ...............................................................................39 6.1.3 Waterborne Pathways..............................................................................40

6.1.3.1 Surface Water Runoff..................................................................40 6.1.3.2 Groundwater Transport ...............................................................40

6.2 EXPOSURE PATHWAY ASSESSMENT......................................................................41

7.0 INTERIM REMEDIAL MEASURE (SEPTEMBER 2003)...........................................42 7.1 IRM OBJECTIVES .................................................................................................42 7.2 IRM WORK PERFORMED......................................................................................42 7.3 ENDPOINT SAMPLE RESULTS................................................................................44 7.4 POST-IRM SOIL VAPOR AND AMBIENT AIR SAMPLING........................................44

7.4.1 Post-IRM Soil Vapor Sampling...............................................................44 7.4.2 Post-IRM Ambient Air Sampling............................................................46

7.5 IRM CONCLUSIONS..............................................................................................46

8.0 SITE REMEDIATION....................................................................................................47 8.1 OPERABLE UNITS .................................................................................................47 8.2 REMEDIAL ACTION OBJECTIVES FOR OU-1 .........................................................47

8.2.1 Exposure Pathway and Transport Considerations...................................47 8.2.2 Remedial Action Objectives for Surface Soils ........................................48 8.2.3 Remedial Action Objectives for Subsurface Structures ..........................49

8.3 RECOMMENDED ADDITIONAL INVESTIGATIONS FOR OU-2...................................50

9.0 SUMMARY OF CONCLUSIONS .................................................................................51 9.1 SURFACE SOILS ....................................................................................................51 9.2 SUBSURFACE SOILS ..............................................................................................51 9.3 SUBSURFACE DRAINAGE STRUCTURES.................................................................51 9.4 SOIL VAPOR .........................................................................................................52 9.5 BUILDING A..........................................................................................................52 9.6 GROUNDWATER....................................................................................................53


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TABLES

Table 1 Analytical Summary of Upper Zone Groundwater, CRA 1996 Table 2 Analytical Summary of Lower Zone Groundwater, CRA 1996 Table 3 Analytical Results for Soil Samples: November 2001 Table 4 Analytical Results for Soil Boring Program: January 2002 Table 5 Sample Control Log: November 2002 Table 6 Underground Drainage Structure Characteristics Table 7A Comparison of Quality Control/Quality Assurance Samples: Soil Media VOCs Table 7B Comparison of Quality Control/Quality Assurance Samples: Soil Media SVOCs Table 7C Comparison of Quality Control/Quality Assurance Samples: Soil Media Inorganics Table 7D Comparison of Quality Control/Quality Assurance Samples: Groundwater Table 8 Analytical Results: Background Surface Soil Samples Table 9 RI Analytical Results: Site Surface Soil Samples Table 10 Analytical Results for Supplemental RI Surface Soil Sampling: Metals Table 11 RI Analytical Results: Subsurface Soil Samples Table 12 Analytical Results for Supplemental RI Subsurface Soil Sampling at Building A Table 13 RI Analytical Results: Soil Vapor Samples Table 14 Analytical Results for Soil Vapor: South Portion of the Site (November 2003) Table 15 Analytical Results for IRM Samples: Volatile Organic Compounds Table 16 Analytical Results for IRM Samples: Semi-Volatile Organic Compounds Table 17 Analytical Results for IRM Samples: Inorganic Compounds Table 18 Analytical Results Summary for Sampling of Cesspool West of Building C Table 19 Analytical Results Summary for Building A Septic System Investigation Table 20 Ambient Air Sampling Results: Building A Table 21 Analytical Results: Upper Zone Groundwater, November 2002 Table 22 Analytical Results: Lower Zone Groundwater, November 2002 Table 23 Hydraulic Head Measurements, November 2002 Table 24 Analytical Results Summary for IRM End Point Samples (September 2003) Table 25 Analytical Results for Soil Vapor Sampling: Main Building Complex (September 2003) Table 26 Analytical Results for Soil Vapor Sampling: Main Building Complex (November 2003) Table 27 Analytical Results for Soil Vapor Sampling: Main Building Complex (June 2004) Table 28 Analytical Results for Ambient Air Sampling: Main Building Complex (June 2004) Table 29A Surface Soil and Subsurface Structure Cleanup Objectives for Organic Chemicals Table 29B Surface Soil Cleanup Objectives for Metals Table 29C Subsurface Structure Cleanup Objectives for Metals


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FIGURES

Figure 1 Site Location Map Figure 2 Site Plan Figure 3 Historic Sample Locations Figure 4 Potentiometric Surface Map Lower Groundwater Zone, December 1996 Figure 5 Potentiometric Surface Map Upper Groundwater Zone, December 1996 Figure 6 Distribution of Chemicals Detected in Upper Zone Groundwater, December 1996 Figure 7 Distribution of Chemicals Detected in Lower Zone Groundwater, December 1996 Figure 8 Regional PSA Groundwater Sampling Locations Figure 9 RI Boring Sample Locations Figure 10 Site Surface Soil Sample Locations Figure 11 Background Surface Soil Sample Locations Figure 12 Soil Vapor Sample Locations Figure 13 IRM Sampling Locations Figure 14 Supplemental RI Approximate Sampling Locations for Surface Soil (09/2003) Figure 15 Building A Sample Locations: Supplemental RI Figure 16 Soil Vapor Monitoring Probes Figure 17 North-South Hydrogeologic Cross-Section of Nassau County Figure 18A Hydraulic Head Distribution Upper Zone Groundwater, November 2002 Figure 18B Hydraulic Head Distribution Upper Zone Groundwater, March 2003 Figure 19A Hydraulic Head Distribution Lower Zone Groundwater, November 2002 Figure 19B Hydraulic Head Distribution Lower Zone Groundwater, March 2003 Figure 20 Chemical Distribution in Background Surface Soil Figure 21A Chemical Distribution in Northern Site Surface Soil Figure 21B Chemical Distribution in Southern Site Surface Soil Figure 22A Chemical Distribution in Northern Underground Drainage Structures: VOCs Figure 22B Chemical Distribution in Southern Underground Drainage Structures: VOCs Figure 23A Chemical Distribution in Northern Underground Drainage Structures: SVOCs Figure 23B Chemical Distribution in Southern Underground Drainage Structures: SVOCs Figure 24A Chemical Distribution in Northern Underground Drainage Structures: Inorganics Figure 24B Chemical Distribution in Southern Underground Drainage Structures: Inorganics Figure 25 Chemical Distribution in Upper Zone Groundwater, November 2002 Figure 26 Chemical Distribution in Lower Zone Groundwater, November 2002 Figure 27 Subsurface Drainage Structures Remediated During September 2003 IRM Figure 28 Approximate Areas of Impacted Surface Soils


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APPENDIXES

Appendix A Historic Soil Boring Logs and Monitoring Well Installation Diagrams Appendix B Remedial Investigation Boring Logs Appendix C Surface Soil Sample Descriptions Appendix D Well Development Logs Appendix E Groundwater Sampling Records Appendix F Data Usability Summary Reports Appendix G Analytical Data Packages (Volumes 2 and 3)

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REMEDIAL INVESTIGATION REPORT TransTechnology Corporation Glen Head Site

Glen Head, New York

1.0 INTRODUCTION

Geomatrix Consultants (Geomatrix) was retained by TransTechnology Corporation (TTC) to conduct a Remedial Investigation (RI) for the TTC property located at One Robert Lane in Glen Head, New York (Site). The Site location is shown on Figure 1. The Site is currently listed in the Registry of Inactive Hazardous Waste Disposal Sites in New York State as Site Number 1-30-101 with a Classification 2. The RI was performed pursuant to the Order on Consent Index # W1-0913-02-02 executed between TTC and the New York State Department of Environmental Conservation (NYSDEC). The RI was conducted in accordance with the Remedial Investigation/Feasibility Study (RI/FS) Work Plan (RI/FS Work Plan) prepared by Geomatrix (dated July 2002). NYSDEC approved the RI/FS Work Plan by letter dated September 27, 2002.

The draft RI Report was submitted to NYSDEC in April 2003. NYSDEC provided comments on the RI by letter dated June 31, 2003. The comments included requests for additional sampling and investigation (Supplemental RI). The results of the Supplemental RI activities have been incorporated in this final RI Report.

The Site has been the subject of a series of previous environmental investigations which have characterized soil and groundwater conditions throughout much of the property. These prior investigations identified chemical presence within a portion of the on-Site septic and leaching system used for sanitary sewage at the Site. Many of the affected cesspools and leaching pools (i.e., subsurface drainage structures) were identified and sampled during investigations conducted by Geomatrix in 2001-2002. The RI/FS Work Plan contains a plan for implementation of an Interim Remedial Measure (IRM) for remediation and closure of selected subsurface drainage structures. To provide data which was needed to develop and implement the IRM, additional sampling from within and around septic system structures was conducted concurrent with the RI sampling activities. Results of the IRM sampling program are included and discussed herein.

This RI Report is organized in eight sections. The remainder of Section 1 presents the Site description and history of Site use and summarizes the results of previous Site investigations.


The RI scope of work and methodology, the IRM sampling, and the Supplemental RI sampling are described in Section 2.0. Section 3.0 describes the Site setting and area land use. Section 4.0 describes the Site hydrogeology. The nature and extent of chemical presence in Site media is characterized in Section 5.0. Section 6.0 presents the results of the qualitative exposure assessment for potentially Site-derived chemicals. The IRM completed in September 2003 is described and documented in Section 7.0. Site remediation is discussed in Section 8.0. Section 9.0 presents a summary of the conclusions of this report.

1.1 SITE DESCRIPTION AND HISTORY Figure 2 presents a Site Plan showing buildings and structures currently located on and adjacent to the TTC property. The Site encompasses 7.75 acres.

The first known manufacturing facilities at the Glen Head Property were constructed in the late 1950s by the Lundy Electronics Company (Lundy). The Site was used by Lundy for a machine shop and electronics manufacturing until approximately 1978. Solvents, including TCE, were reportedly used at the facility during this time. After 1978, machining activities were discontinued and solvent use at the Site was reduced. Lundy was acquired by TTC in the mid 1980s. TTC ceased operations at the facility in 1994. The building space at the Site is currently leased to a variety of small businesses.

There are several buildings on the Site. These include a one-story house at 4 Dumond Place which is leased as a residence (Building A on Figure 2). Building A was formerly used by Lundy as an R&D facility. Buildings B and C are one-story concrete block structures currently leased to Custom Cove, Inc. (a canvas repair firm). Building D is leased to East Coast Stone Works. Buildings C and D were formerly connected by an enclosed storage area and functioned as one building. The buildings were formerly used for circuit board cleaning and wave soldering operations.

The remainder of the facility was housed in a group of joined buildings which were expanded over time from south to north (Buildings E, F, G, H and I on Figure 2). The former locations of the degreasing and plating operations in these buildings are indicated on Figure 2. The remainder of the facility was used primarily for maintenance, assembly, packaging and shipping, storage and office space. Material storage occurred on concrete pads located behind (east of) Buildings E and G.


Sanborn Maps for Glen Head dated 1932, 1943 and 1964 were reviewed to provide additional historical information for the Site and nearby surrounding properties. In 1932, there was a cleaning and pressing shop located at the intersection of Dumond Place and North Glenwood Road. In 1943, a filling station was located east of the cleaners and there was a water tower north of 4 Dumond Place. According to the 1964 Sanborn Map, the Sea Cliff Water Company owned most of the parcel.

Several private residences are located on adjacent properties to the west. The Sea Cliff Water District continues to operate a water storage tower on its property on Dumond Place (west of the Site). There is an automobile repair shop and retail stores to the south and a Long Island Railroad right of way to the east. Also to the east, there is an electrical substation and a Town of Oyster Bay equipment and road material storage yard.

The Site is relatively flat with surface water draining to a series of catch basins along the driveways and parking areas which act as dry wells and are identified as leaching pools on Figure 2. Sanitary waste system at the Site drains to cesspools connected to leaching pools. The cesspools, and leaching pools located adjacent to and east of Building E, F and G (near the former degreasing and plating operations) contain elevated levels of trichloroethene (TCE) and metals.

1.2 SITE INVESTIGATIONS CONDUCTED PRIOR TO THE RI In 1992, an underground fuel oil storage tank located behind Building G was removed from the property and a soil boring was drilled to the water table to check for fuel oil contamination. A groundwater sample was collected and analyzed and fuel oil constituents were not found. However, levels of halogenated volatile organic chemicals (VOCs) unrelated to fuel oil were found; including TCE at 44 micrograms per liter (µg/l), 1,1,1-trichloroethane (TCA) at 20 µg/l, and tetrachloroethene (PCE) at 2.5 µg/l. Nassau County Department of Health (NCDOH) and NYSDEC were notified of these findings, and site investigations were initiated to identify the source of the VOCs in accordance with NYSDEC requirements. Subsequent follow up environmental investigations were conducted to further characterize the Site. The results of all previous environmental investigations are summarized and discussed below.

1.2.1 ERM and Eder Investigations (1992-1993) During 1992 and 1993, three environmental investigations were performed at the Site. In 1992, ERM conducted a hydrogeologic assessment in anticipation of a property transfer. The investigations consisted of installation and sampling of three water table monitoring wells


(designated MW-1, MW-2 and MW-3) near the former fuel oil tank, the abandoned industrial waste cesspool (behind building E), and sanitary cesspools (leaching pools). In addition, one soil boring was drilled in the vicinity of a former material storage pad (between Buildings D and E). Historic monitoring well locations are shown on Figure 3.

In December 1992, Eder was retained through Nixon, Hargrave & Doyle to conduct Phase I and Phase II Environmental Audits of the facility. The investigative work performed consisted of the following:

i) soil vapor survey;

ii) collection of soil samples from three soil borings; and

iii) installation and sampling of three additional water table monitoring wells (designated MW-4, MW-5 and MW-6).

The Eder and ERM investigations showed the following:

1. Tetrachloroethene measured in groundwater at the Site migrated to the property from an upgradient source. The source(s) is (are) most likely a former dry cleaning establishment and/or an active dry cleaning establishment, both located immediately south of the property.

2. Trichloroethene also appears to have migrated onto the property from upgradient sources, however, the trichloroethene distribution in groundwater could indicate that an on-Site release of trichloroethene may have also occurred.

3. Additional data would be necessary to characterize the vertical distribution of volatile organic chemicals (VOCs) in soil near the previously identified potential contaminant source area (the vicinity of the former chemical storage area and leaching pools).

4. Additional data would be necessary to characterize the vertical distribution of VOCs in groundwater.

1.2.2 CRA Investigation (1996)

1.2.2.1 Objectives and Scope of Work In 1996, Conestoga-Rovers and Associates (CRA) was retained to conduct an investigation of subsurface soil and groundwater at the Site. The objectives of the CRA environmental investigation were to:


1. characterize the horizontal and vertical extent of on-Site groundwater contamination; and

2. characterize the vertical distribution of VOCs in soil near the former drum storage area and leaching pools.

The following scope of work was performed:

1. Installation of two soil borings to the water table (approximately 100 feet below ground surface {bgs}) in the vicinity of the drum storage area and nearby leaching pools. Split-spoon samples were obtained at 10-foot intervals and screened with a photoionization detector (PID). Three samples from each boring were submitted for analysis of VOCs.

2. Installation of two shallow monitoring wells (MW-8 and MW-10) screened from approximately 110 to 120 feet bgs. These wells were located adjacent to Building G and in the north parking lot (Figure 3).

3. Installation of three deep monitoring wells ( MW-7, MW-9 and MW-11) at the locations of existing wells MW-2 and MW-3, and in the north parking lot (Figure 3). The deep wells were screened from approximately 125 to 150 feet bgs.

4. Sampling of all Site monitoring wells for VOC analyses (11 wells total).

1.2.2.2 CRA Investigation Results Hydrogeology: Historic boring logs and well installation diagrams are included in Appendix A. In general, the soil samples obtained during drilling activities indicate the presence of fine to coarse sand and gravel deposits to depths of at least 150 feet bgs. Occasional silt and micaceous interbeds occur at depths below 60 feet bgs. Geophysical logs and soil sampling logs from the ERM investigation indicate silt and sandy silt interbeds, approximately 10 to 30 feet in thickness, are present at wells MW-1, MW-2, and MW-3. At depths below 140 to 150 feet bgs (at MW-7, MW-9, and MW-11) finer deposits of silt and sand occur with clay seams or lenses and traces of fine gravel. These finer deposits are characteristic of the sediments that comprise the Magothy Formation and may indicate a transition to the Magothy below the Site.

The Upper Zone wells are screened across the water table and are approximately 120 feet deep; the Lower Zone monitoring wells monitor the saturated zone between 125 and 150 feet deep. Based on measurements obtained in December 1996, the groundwater flow at the Site is toward the northwest. Figures 4 and 5 present potentiometric surface maps for the upper and lower zones, respectively. The hydraulic head distribution shows an approximate horizontal hydraulic gradient of 0.002 for both the Upper and Lower zones. Vertical hydraulic gradients


calculated for adjacent well pairs are downward and range from 0.003 at monitoring well pairs MW-7/8 and MW-2/9 to 0.009 at monitoring well pair MW-3/11.

Chemical Presence: Soil samples were screened with a PID from boreholes at 10-foot intervals. The measurements were generally low, with no values in excess of 23 parts per million (ppm). These results suggest that high concentrations of VOCs do not occur in soil near the sampling locations.

Two soil borings were advanced to obtain soil samples for chemical analyses in the vicinity of the former drum storage area and leaching pools. Soil boring locations are shown on Figure 3. VOCs were detected in two samples as follows:

Boring Depth Interval Chemical Concentration (ft. bgs) (mg/kg) SB-1 30 - 32 4-Methyl-2-pentanone 1J MW-11 70 - 72 1,2-Dichloroethene (total) 3J MW-11 70 - 72 Trichloroethene 15 J - Associated value is estimated. All other VOC results were non-detect. These results suggested no major presence of VOCs in the area which had been identified as a potential VOC source area in previous preliminary investigations. The results of the soil sampling program indicated that residual VOC contamination in soil at the Site, if present, was not widespread.

The analytical results for Upper Zone groundwater (defined by CRA as the upper 10 feet of the saturated zone, occurring between approximately 110 and 120 feet bgs) samples are summarized as follows:


Number Detects/ Maximum Chemical Number Samples Concentrations (ug/l) 1,1-Dichloroethene 2/8 4J 1,2-Dichloroethene (total) 7/8 310 1,1-Dichloroethane 5/8 15 1,1,1-Trichloroethane 7/8 41 Trichloroethene 7/8 1,800 1,2-Dichloropropane 1/8 4J Tetrachloroethene 7/8 16,000 J - Associated value is estimated. The analytical results for groundwater samples collected in 1996 are presented in Table 1.

The distribution of chemicals detected in Upper Zone groundwater samples collected in 1996 is shown on Figure 6. Tetrachloroethene occurred at the highest concentrations (by approximately one order of magnitude). As illustrated on Figure 6, tetrachloroethene is more highly concentrated upgradient (south) of the Site than on-Site or downgradient, indicating an off-Site source. The highest concentration was measured in upgradient well MW-4, which is located adjacent to a former dry cleaning establishment. According to CRA, the groundwater flow pattern and tetrachloroethene concentration distribution is inconsistent with an on-Site tetrachloroethene source.

Trichloroethene was also detected, however, its maximum concentration was measured on-Site at well MW-2 (1,800 µg/L). According to CRA, trichloroethene is a biochemical breakdown product of tetrachloroethene and could be originating from the off-Site tetrachloroethene source. However, CRA provided an alternate explanation that the trichloroethene concentration distribution could potentially be reflective of an on-Site trichloroethene source. Other biological breakdown products of tetrachloroethene detected at the Site during the 1996 sampling event include 1,2-dichloroethene and 1,1-dichloroethene. There were no chemicals detected in samples collected from the downgradient Upper Zone monitoring well, MW-8.

The Lower Zone groundwater is defined by CRA as the 25 foot interval underlying the Upper Zone. The Lower Zone interval occurs between approximately 125 and 150 feet bgs. Three Lower Zone monitoring wells were installed. Table 2 presents the measured concentrations of all chemicals detected in Lower Zone groundwater samples for the December 1996 sampling event.


Eight VOCs were detected as summarized in the following.

Number Detects/ Maximum Chemical Number Samples Concentrations (ug/l) 1,1-Dichloroethene 1/3 4J 1,2-Dichloroethene (total) 1/3 3J 1,1-Dichloroethane 2/3 3J 1,1,1-Trichloroethane 1/3 2J Trichloroethene (TCE) 2/3 13 Toluene 1/3 2J Tetrachloroethene (PCE) 1/3 6J Xylenes 1/3 2J J - Associated value is estimated. Only one chemical was measured above the analytical reporting limit (trichloroethene at 13 ug/L). Figure 7 depicts the concentration distribution in the Lower Zone. These results suggest that vertical (downward) migration of VOCs has been limited and that deep groundwater at the Site is not significantly impacted.

1.2.3 Preaquisition Soils Investigation

1.2.3.1 Scope of Work Geomatrix was retained in 2001-2002 to conduct the additional investigations of cesspools and leaching pools at the Site. The investigation was conducted at the request of a potential buyer of the Site. During November 14-19, 2001, Geomatrix sampled sediment accumulations from four cesspools, two drains and 14 leaching pools at the Site using Geoprobe® and hand auger samplers. In addition, four soil borings were advanced near the former material storage locations. Samples were analyzed for TCL VOCs, TCL SVOCs and RCRA Metals. Locations of sampled leaching pools, drains and cesspools are shown on Figure 3.

Based on the results of the November 2001 sampling event, additional soil borings were advanced in January 2002 to collect subsurface soil samples adjacent to cesspools and leaching pools which had shown elevated chemical concentrations in sediment. The purpose of the soil boring program was to assess whether significant migration of chemicals to soils surrounding the subsurface structures had occurred. Soil boring locations are shown on Figure 3. A total of 12 soil borings were advanced to depths up to 24 feet.


1.2.3.2 Results and Conclusions Historic soil boring logs are included in Appendix A. The results of the November 2001 sampling event are summarized in Table 3. The results of the January 2002 soil boring program are presented in Table 4.

The results of these studies showed elevated VOC and/or metals concentrations in sediment sampled from the following structures (see Figure 3 for locations): C-3, C-4, C-5, LP-3, LP-9, LP-11, LP-13 and LP-16. In addition, polyaromatic hydrocarbons (PAHs) were detected in several parking lot drains at concentrations typical of urban drainage basins.

The results of the January 2002 soil boring program indicate that very little horizontal migration from the structures to surrounding soils has occurred (see Table 4).

1.2.4 NYSDEC Preliminary Site Assessment Report Glen Head Groundwater Plume (September 2000) A Preliminary Site Assessment (PSA) was conducted by NYSDEC to investigate an area of impacted groundwater referred to as the Glen Head Groundwater Plume (Site No. 1-30-098). This study was not specific to the TTC Glen Head Site, but rather investigated groundwater in the vicinity of the Site. The study primarily targeted one active and four former dry cleaning facilities as potential sources of tetrachloroethene and other VOCs. A total of 11 monitoring wells were installed and sampled (Figure 8). In addition, groundwater samples were obtained using a hydropunch at four locations. The monitoring wells were installed at approximately the same depth as the TTC shallow monitoring wells.

The PSA showed widespread presence of tetrachloroethene in groundwater throughout the study area at concentrations up to 18,000 ug/L. Trichloroethene was present at far lower concentrations (up to 130 µg/L) compared to tetrachloroethene. The comparatively low levels of trichloroethene detected suggest that this compound may be present due to degradation of tetrachloroethene. 1,2-Dichloroethene (1,2-DCE), another potential tetrachloroethene degradent, is similarly present at low concentrations relative to tetrachloroethene. This suggests degradation of tetrachloroethene is a potential source of trichloroethene and 1,2-DCE.

These results of the PSA indicate that the TTC Site is located in an area where groundwater is impacted by relatively high concentrations of tetrachloroethene, with trichloroethene presence at lower levels which could be attributable to tetrachloroethene degradation.


2.0 REMEDIAL INVESTIGATION SCOPE OF WORK AND METHODS

The RI was conducted in accordance with the RI/FS Work Plan prepared by Geomatrix (dated July 2002). NYSDEC approved the RI/FS Work Plan by letter dated September 27, 2002. The approved RI/FS Work Plan describes all field and analytical methods and contains the following supplemental work plans:

Quality Assurance Project Plan Field Sampling Plan Health and Safety Plan Community Air Monitoring Plan Citizen Participation Plan

2.1 RI OBJECTIVES The objective of the RI is to characterize the nature and extent of chemical presence in soil and groundwater attributable to past releases at the Site. To meet this objective, additional data were collected to supplement the results of the previous Site investigations.

2.2 RI SAMPLING RATIONALE As described in Section 1.2, a large amount of Site characterization data had already been developed for the property. This has included sampling of soils from 18 soil borings and sampling of groundwater from 11 monitoring wells. In addition, sediments from 5 cesspools, 16 leaching pools and soils beneath 2 interior building drains were sampled prior to this RI.

On-site groundwater has been well characterized using the existing monitoring network of 11 wells. However, the most recent groundwater sampling event was performed in 1996. To obtain current groundwater chemistry data for use in this RI, all existing monitoring wells were resampled for analysis of Target Compound List (TCL) VOCs and Inorganic Target Analyte List (TAL) Metals using ASP 2000 Methodology. Prior to sampling, all monitoring wells were inspected and redeveloped to remove accumulated fines.

Off-Site groundwater had not been investigated as part of past TTC Site investigations. However, as described in Section 1.2.4, a regional groundwater investigation has been conducted by NYSDEC in the area. One of the wells installed by NYSDEC (designated MW-7) is located downgradient of the TTC Site (based on hydraulic heads measured in the NYSDEC monitoring wells). This well was included in the RI groundwater sampling event to monitor off-site, downgradient groundwater.


As part of the prior investigations, soil borings had been drilled and sampled throughout areas of the Site not covered by buildings. However, soil sampling beneath the building slabs had been limited to soil borings at two locations (D-3 and D-4 on Figure 3) beneath interior trench drains. Additional soil borings were advanced during the RI adjacent to and within the buildings associated with the former manufacturing activities (Buildings D, E, F, G, H, and I) to further characterize soils currently covered by these buildings. At selected soil boring locations, soil vapor samples were obtained.

The previous environmental investigations showed no evidence that chemical release to surface soils has occurred at the Site. However, to evaluate potential exposures via direct contact, surface soil samples were collected during the RI from areas of the Site which are unpaved and uncovered by buildings. In addition, background surface soil samples were collected from areas distant from and upgradient (with respect to surface drainage) of former operating areas of the Site.

As described in Section 1.0, collection of additional soil/sediment characterization data was necessary for completion of the IRM. The IRM Investigation sampling program consisted of sampling subsurface structures (cesspools, drains and leaching pools) not previously sampled, resampling of selected subsurface structures, and sampling from soil borings located adjacent to impacted subsurface structures. After completion of the IRM, additional sampling of soil vapor and indoor air within the main building complex was performed (Post-IRM sampling).

As indicated in Section 1.0, Supplemental RI tasks were requested by NYSDEC in their comments on the Draft RI Report. The requested activities included additional sampling of soils, sediments, soil vapor and indoor air.

RI, IRM investigation, and Supplemental RI tasks are described in detail below. Post-IRM sampling is described in Section 7.4.

2.3 REMEDIAL INVESTIGATION TASKS This section describes the tasks performed to address the additional data needs for Site characterization. RI field activities were conducted by Geomatrix in accordance with the Site Health and Safety Plan (HASP) presented in Appendix C of the RI/FS Work Plan. Environmental sample collection was performed in accordance with the Field Operating Procedures (FOPs) presented in the Field Sampling Plan (FSP) presented in Appendix B of the


RI/FS Work Plan and the Quality Assurance Project Plan (QAPP) presented in the Appendix A of the RI/FS Work Plan.

The Scope of Work for the RI consisted of the following tasks:

• Task 1: Soil Boring Program

• Task 2: Surface Soil Sampling

• Task 3: Monitoring Well Redevelopment

• Task 4: Hydraulic Head Monitoring

• Task 5: Groundwater Sampling

• Task 6: Soil Background Sampling

• Task 7: Soil Vapor Screening and Sampling

2.3.1 Task 1: Soil Boring Program To further characterize the soil associated with the main manufacturing activities, a total of sixteen soil borings were advanced using direct push (Geoprobe®) methods during November 12-15, 2002. Twelve of the borings were located within the interior of the Building E through I complex as shown on Figure 9. One soil boring, RI-1, was terminated early due to refusal at 4 feet bgs. A deeper boring (RI-1A) was drilled 15 feet east of RI-1.

Except for RI-1, all borings were advanced to depths of 16-feet bgs. Continuous soil samples were examined for visual evidence of impact (e.g., staining) and characterized according to soil type by a qualified Geomatrix field engineer. Soil samples were screened in 2-foot intervals for the presence of volatile organic chemicals (VOCs) using a photoionization detector (PID). Soil boring logs are provided in Appendix B.

A minimum of one sub-surface soil sample was collected from each boring for chemical analysis based on PID, visual and/or olfactory evidence of impact. If no soil sample from the boring exhibited evidence of impact, the sample was collected from the upper 2-feet of soil (non-gravel backfill) below the building slab. Two soil intervals were collected for laboratory analysis from borings RI-5, RI-9, RI-11, RI-12, RI-13, RI-14, and RI-15 to characterize the shallow and deep interval soil samples. A summary of the samples collected is provided in Table 5.


Samples for chemical analysis were collected using dedicated and disposable stainless steel sampling spoons and placed in laboratory provided, certified clean, glass sampling jars. Each sample was given a unique nine-digit sample identification code and placed on ice. Samples were shipped overnight under chain-of-custody procedures to Columbia Analytical Services (Columbia) in Rochester, New York for analysis of Target Compound List (TCL) VOCs by Method OLM 4.2 and Inorganic Target Analyte List (TAL) Metals by Method ILM 4.1.

2.3.2 Task 2: Surface Soil Sampling To evaluate potential chemical exposures via direct contact, 22 surface soil samples were collected November 2, 14, and 18, 2002. Surface soil samples were located throughout the Site in unpaved areas as shown on Figure 10. Each surface soil sample was sent to Columbia for analysis of TCL VOCs by Method OLM 4.2 and Inorganic TAL Metals by Method ILM 4.1.

VOC samples were collected from a discrete sample location while metal samples were a composite of four sub-sample locations within a one square meter area. Each sample was collected from 0 to 4-inches below the sod layer which was cleared with a shovel or trowel. Sample collection and compositing was performed in accordance with the FOPs in Appendix B of the RI/FS Work Plan.

A description of each sample is provided in Appendix C. A summary of the samples collected is provided in Table 5.

2.3.3 Task 3: Monitoring Well Redevelopment To assess the current condition of each existing groundwater monitoring well, an inspection was conducted on October 28, 2002. The inspection included examinations of the protective surface casings, riser pipes, and the annular spaces. The depth to water and total depth of each well was measured and compared to previous measurements and well installation logs to determine if well obstructions were present. Each well was measured to be consistent with previous data and determined to be usable for the RI.

Dedicated and disposable bailers were used to surge the entire length of the well screen and remove water from the on-Site wells in accordance with the FOPs presented in Appendix B of the RI/FS Work Plan. For each well volume of water removed, field parameters (temperature, pH, specific conductivity, and turbidity) were measured using field instruments. Development was considered complete when a minimum of ten well volumes was purged and differences


between measurements were less than 10% difference over three or more well volumes or a turbidity goal of less than 50 NTU was achieved.

Monitoring wells MW-1 through MW-10 were developed during the week of October 28, 2002 and monitoring well MW-11 was developed on November 13, 2002. Purge water was containerized on-Site for proper off-Site treatment/disposal. Well development logs are included in Appendix D.

2.3.4 Task 4: Hydraulic Head Monitoring Hydraulic head measurements were obtained on November 15, 2002 and March 19, 2003 from the on-Site wells (MW-1 through MW-11) and the NYSDEC off-site downgradient well (designated NYSDEC MW-7). Hydraulic head was measured with an electronic water level indicator to the nearest hundredth of a foot as described in the FOPs included in Appendix B of the RI/FS Work Plan.

2.3.5 Task 5: Groundwater Sampling and Analyses All of the on-Site groundwater monitoring wells (MW-1 through MW-11) and the off-Site well (NYSDEC MW-7) were sampled the week of November 11, 2002.

Upgradient groundwater monitoring wells (MW-4 and MW-5) were sampled first. Prior to sample collection, the groundwater elevation was recorded in each well and the well was purged using dedicated and disposable bailers. Purge water was containerized on-Site for proper off-Site treatment/disposal.

Hand held field instruments were calibrated daily in accordance with the FOPs in Appendix B of the RI/FS Work Plan to measure groundwater parameters between well volumes. Field measured parameters included: temperature, pH, specific conductivity, dissolved oxygen, oxidation-reduction potential and turbidity. A minimum of three well volumes was purged from each well or until field measured parameters were stabilized. Stabilization was achieved after three field parameter readings are within + 0.1 unit for pH, + 3% for specific conductivity, + 10 millivolts for oxidation-reduction potential, and + 10% for turbidity and dissolved oxygen. Groundwater sampling records are provided in Appendix E.

Groundwater samples were collected for analysis of TCL VOCs by Method OLM 4.2 and Inorganic TAL Metals by Method ILM 4.1. A summary of the samples collected is provided in Table 5. Each sample was collected in pre-preserved, laboratory provided, certified clean


sample containers, labeled with a unique nine-digit sample identification code, and placed on ice for shipment. Samples were sent to Columbia Analytical Services under chain-of-custody procedures, as described in the FOPs in Appendix B of the RI/FS Work Plan.

2.3.6 Task 6: Background Soil Sampling Five background surface soil samples were collected along the western boundary of the Site at locations shown on Figure 11. The background locations were chosen to represent areas that do not receive runoff from the former operating portions of the Site or from the railroad tracks adjacent to the eastern boundary of the Site.

Background surface soil samples were collected using the same methods as the surface soil samples (Section 2.3.2). Each background surface soil sample was sent to Columbia and analyzed for TCL VOCs, TCL Semi-Volatile Organic Compounds (SVOCs) and Inorganic TAL Metals.

2.3.7 Task 7: Soil Vapor Screening and Sampling As described in the RI/FS Work Plan, soil vapor monitoring points were installed in six of the soil borings located within the Building E through I complex. At completion of soil borings RI-3, RI-6, RI-7, RI-9, RI-11, and RI-15 (Figure 12), soil vapor monitoring points were constructed with a one-inch diameter PVC riser pipe and well screen (0.01 slot size). The monitoring points were set to screen the soil intervals with the maximum PID measurements. Screen lengths ranged from 5 to 10 feet. Each monitoring point was completed with sand pack and a bentonite chip/cement seal. Monitoring point construction details are included on the boring logs in Appendix B.

The soil vapor monitoring points were undisturbed for a minimum of four days and field screened with a PID for the presence of VOCs on November 18, 2002. The PID readings ranged from background levels to 8.0 part per million (ppm). The latter was measured in RI-6 (the approximate location of former degreasing and chrome plating activities).

Soil vapor samples were collected from each monitoring point using 6-liter summa canisters. Dedicated tubing was connected to each canister and inserted into the well headspace several feet below the top of the PVC riser. The canister vacuum was released and the canister was filled according to the manufacturer’s recommendations.


Each canister was given a unique nine-digit sample identification code and submitted under chain-of-custody procedures to the Columbia Analytical Services air laboratory in Simi Valley, California, for analysis of VOCs by EPA Method TO-15.

2.4 IRM INVESTIGATION SAMPLING PROGRAM 2.4.1 IRM Objective and Scope The objective of the IRM conducted in September 2003 was to remove the soil/sediment from selected cesspools and leaching pools that contain elevated concentrations of volatile organic compounds (VOCs). This will minimize the potential for migration of VOCs and reduce potential future human exposures to impacted soils/sediments within these structures. The leaching pools and cesspools are of the standard leaching pool design used in this area of Long Island. This consists of stacked cement rings (4 feet high and 8 or 12 feet in diameter) with 4 inch square leaching outlets spaced 10 inches apart around the circumference. Some of the structures were found to have hard cement bottoms and some were found to have open bottoms. Table 6 summarizes observations made during the November 2001 sampling event.

As described in Section 8.2, the IRM consisted of the removal of soil and sediment from within selected subsurface structures identified as potential sources of VOC contamination in groundwater. In order to develop the specifics of the IRM, including selection of structures to be remediated and estimated volumes of impacted materials to be removed, sediment within and soil surrounding underground structures at the Site was sampled. This IRM sampling program is described below.

2.4.2 IRM Soil Borings Cesspools C-3 and C-4 contained the highest levels of VOCs based on the previous investigations. Soil borings previously advanced close to these structures (SB-1-96, B-1-02, and B-2-02) suggest that soils surrounding the structures have not been significantly impacted. To confirm this, two additional soil borings were advanced during the RI immediately adjacent to the outside of cesspools C-3 and C-4.

Continuous soil samples were collected at the borehole locations shown on Figure 13 to a minimum depth of 12 feet below grade. Soil samples were screened for organic vapors with a PID at one foot intervals. The interval with the highest organic vapor reading was collected for laboratory analyses of VOCs.


2.4.3 IRM Subsurface Structure Sampling Samples of soil/sediment were collected from within previously unsampled leaching pools LP-12, LP-14 and LP-15 to a minimum depth of 8 feet below the top of the sediment surface within each leaching pool or to the concrete bottom (whichever was encountered first). Soil samples were screened for organic vapors using a PID. The interval with the highest organic vapor reading and the first underlying “clean” interval (to be determined based on organic vapor readings) were submitted for analyses of TCL VOCs. These data will be used to determine if removal of the sediment/soil from LP-12, LP-14 and/or LP-15 is necessary and the initial excavation depths (if excavation is necessary).

Previously unsampled leaching pools (LP-4, 5, 6, 8, 10, 18, 20-31, and 32) and one cesspool (C-1) were sampled (for TCL VOCs and inorganic TAL metals) as described above.

In addition, the following structures were resampled for the indicated analyses: LP-1 (TCL VOCs), LP-2 (TAL metals), LP-3A (TAL metals, TCL VOCs, TCL SVOCs), LP-7 (TAL metals, TCL SVOCs), LP-17 (TCL VOCs, TCL SVOCs), LP-19 (TCL VOCs), LP-31A (TCL SVOCs), LP-33 (TCL VOCs), LP-34 (TAL metals) and C-6 (TAL metals).

Sample locations are shown on Figure 13. The results of these analyses were used to select the structures to be remediated as part of the IRM (see Section 8.2).

2.5 RI QUALITY ASSURANCE/QUALITY CONTROL MEASURES All field investigation data were collected and processed using the procedures outlined in the QAPP and the FSP provided in Appendix A and B, respectively, of the RI/FS Work Plan to ensure representative sample collection and to achieve the data quality objectives of the Remedial Investigation. The field activities were recorded in bound project field books containing field forms from the FOPs in the FSP.

Geomatrix collected blind duplicates and matrix spike/matrix spike duplicates (MS/MSD) at a frequency of one in every 20 samples for soil and groundwater samples. A trip blank, analyzed for TCL VOCs accompanied each cooler of aqueous media to be analyzed for VOCs. All of the sampling equipment was dedicated and disposable. Duplicate and MS/MSD sample locations are identified in Table 5. The correlation between samples and duplicate samples are provided in Table 7A (VOCs in soil), Table 7B (SVOCs in soil), Table 7C (Inorganics in soil), and Table 7D (groundwater).


The laboratory provided complete data packages suitable for data validation. Data packages were validated by a third party data validator, Ms. Judy Harry of Data Validation Services in North Creek, New York using the most current editions of the USEPA CLP National Functional Guidelines for Organic and Inorganic Data Review and the USEPA Region 2 SOPs HW0-2 and HW-6. Data Usability Summary Reports (DUSR) are provided in Appendix F.

Data validation reported usable data with minor edits to non-detect or qualification as estimated. None of the data was rejected. In general, validation edits and qualifications result from:

• A trip blank submitted November 11, 2002 (TB111202) detected acetone (9 ug/L) resulting in editing detections less than 90 ug/L to non-detect.

• Accuracy and precision were generally acceptable with the exception of several metals. Antimony showed consistently low recovery.

• Correlations of sample to blind duplicate sample results were within validation guidelines with the exception of IRM sample LP-5-1 and duplicate sample LP-51-1. The volatile analysis showed poor correlation which may be due to low solids content (14% and 15%). All of the sample results have been qualified as estimated for LP-5-1 and LP-51-1.

Based on assessment of precision, accuracy, and completeness, sample collection and laboratory analyses met data quality objectives of the remedial investigation.

2.6 SUPPLEMENTAL RI In a letter dated July 31, 2003, NYSDEC requested additional sampling of soil and soil vapor at the Site. The additional sampling requested in this letter consisted of the following:

1. Collection of additional surface soil samples to better delineate areas where background levels and/or guidance values were exceeded based on the RI sampling.

2. Additional investigation of Building A including collection of subsurface soil and soil vapor samples, and collection of indoor (basement) and outdoor ambient air samples.

3. Sediment sampling from Cesspool C-2 and sampling of sediment from a septic tank located west of Building C.


TTC elected to conduct some additional sampling of soil vapor and indoor air beyond that requested in the July 31, 2003 letter. These additional sampling activities included: installation and sampling of soil vapor probes installed throughout the southern portion of the Site; soil borings within the current and former septic system at Building A; and followup sampling of Building A ambient air.

Supplemental RI tasks are described in detail below.

2.6.1 Supplemental RI Task 1: Supplemental Surface Soil Sampling Four surface soil locations sampled during the RI were found to contain one or more metals at concentrations above NYSDEC guidance values and/or background levels. These locations (shown on Figure 11) are Surf-15, Surf-16, Surf-17, Surf-19, Surf-20, and Surf-22. These locations were further investigated during September 2003 by collecting three additional samples from each area to determine the extent of any soil remediation which may be required. Surface soil samples were collected from points surrounding the previous RI sample location and analyzed for TAL metals in accordance with the RI/FS Work Plan. Figure 14 shows Supplemental RI surface soil sampling locations.

2.6.2 Supplemental RI Task 2: Building A Investigations Building A (see Figure 2) is a small, two-story structure currently leased for residential occupancy. It is located at the far southwestern corner of the Site. It has a walk-in basement, accessible from the rear of the house. Building A is located on the portion of the property closest to current and former dry cleaning operations which are suspected by NYSDEC to be responsible for widespread PCE contamination in groundwater throughout this portion of the Village of Glen Head (see the NYSDEC Report titled “Preliminary Assessment Report, Glen Head Groundwater Plume, Village of Glen Head (Site Number 1-30-098)” dated September 2000). At the request of NYSDEC, as part of the Supplemental RI samples of ambient indoor air, ambient outdoor air, soil gas, and subsurface soil were collected from within and around Building A. These activities are described below.

2.6.2.1 Building A Ambient Indoor Air One ambient air sample was collected from the basement of Building A on September 4, 2003. All windows were closed and the air conditioning was shut off for approximately two and one half hours prior to collecting the sample. The basement contained a variety of household cleaning products and paints. A fuel oil burning furnace is also located in the basement.


The ambient air sample was collected using a 6-liter Summa canister with a 30-minute flow controller. The air sample was analyzed for VOCs by EPA Method TO-14A.

A second ambient air sampling event was conducted within Building A on November 18, 2003. During this sampling event, ambient indoor air samples were collected from two locations in the residential living spaces. One sample was collected from a section of the basement floor which has been finished as a living space and bedroom (within one room). A second indoor air sample was collected from the kitchen located on the floor above the finished room in the basement.

2.6.2.2 Building A Ambient Outdoor Air As part of the sampling events conducted on September 4, 2003 and November 18, 2003, samples of the ambient air outside of Building A were collected for comparisons with the indoor air samples. The samples were collected on the south side of the building, near its wall, from a height of approximately 1.5 feet. Sample collection and analysis was as described in Section 2.6.2.1, above.

2.6.2.3 Building A Subsurface Soil and Soil Vapor Sampling Figure 15 shows the locations of Supplemental RI sampling locations at Building A. On September 4, 2003, one soil boring (FS-1) was advanced within 2 feet of the building wall (along its south side) to a depth of 20 feet. One subsurface soil sample was collected for analysis of TCL VOCs and TAL metals. The soil boring was advanced and the sample was collected as described in the RI/FS Work Plan. Field screening of the soil samples from this boring with a PID showed no measurable VOCs in any sample. The sample from the 10-12 foot depth interval was submitted for chemical analysis. A soil vapor probe was installed in the boring and sampled in accordance with the approved RI/FS Work Plan. The vapor probe was screened at the estimated depth of the interface between the building foundation and underlying soil (7 to 12 feet BGS).

On November 18, 2003, two additional soil vapor probes were installed adjacent to Building A as part of the supplemental investigation of soil vapor in the southern portion of the Site. One soil vapor probe (SVP-7) was installed adjacent to west side of the building and the other (SVP-1) was installed adjacent to the east side of the building. Installation of these probes is discussed in Section 2.6.4, below.


2.6.2.4 Building A Septic System Investigation On September 20, 2004, two soil borings were advanced at Building A to investigate the current and former septic system. Soil boring locations are shown on Figure 15. One boring was located within the currently operating cesspool (A-1) and the second (A-2) was drilled though a former septic tank which had collapsed and was replaced. The former tank was reportedly in operation prior to conversion of Building A to residential use.

The soil borings were advanced using direct push (Geoprobe®) methods in accordance with the RI/FS Work Plan. Borehole depths and section of samples for chemical analyses were determined in consultation with the NYSDEC on-Site representative. Continuous soil samples were collected to a depth of 10 feet below the top of cesspool sediment at boring A-1 and to a depth of 16 feet below ground surface at boring A-2. In boring A-1, samples for chemical analyses were submitted from the following depth intervals (measured below top of cesspool sediment): 6 to 10 inches; 10 to 23 inches; and 9.5 to 10 feet. In boring A-2, samples for chemical analyses were submitted from the following depth intervals (measured below ground surface): 5 to 6 feet; 6.2 to 7 feet; 9 to 10 feet; 12 to 14 feet; and 14 to 16 feet. Samples were analyzed for chlorinated VOCs in accordance with the RI/FS Work Plan.

2.6.3 Supplemental RI Task 3: Supplemental Cesspool Sampling Cesspool C-2 was not sampled during the RI because it was found to have a fused concrete cover which could not be opened. This cesspool was sampled as part of the Supplemental RI on September 4, 2003. The sample was collected by drilling through the concrete cover with a Geoprobe. The structure was found to contain approximately 16 feet of water. Bottom sediments were encountered at approximately 20 feet BGS. A sample of the upper 1.5 feet of sediment was collected with the Geoprobe® and analyzed for TCL VOCs, TCL SVOCs ands TAL metals.

The presence of a septic tank west of Building C could not be confirmed during the field inspections conducted during the RI investigations conducted in 2002. This cesspool location was confirmed and the cesspool was sampled as part of the Supplemental RI on September 4, 2003. Access for Geoprobe® sampling was through a 6-inch pipe leading into the structure. Three feet of liquid was present. Sediment/sludge was encountered at 8 feet BGS. A sample of the upper 2.5 feet of sediment/sludge was collected and analyzed for TCL VOCs, TCL SVOCs ands TAL metals.


2.6.4 Supplemental RI Task 4: Soil Vapor Sampling-South Portion of Site Seven soil vapor monitoring probes were installed during November 2003 in soil borings located throughout the southern portion of the property as shown on Figure 16. The probes are designated SVP-1 through SVP-7. As indicated in Section 2.6..2.3, two of the probes were located adjacent to Building A (SVP-1 and SVP-7), one on the east side and one on the west side.

The soil vapor monitoring points were constructed with a one-inch diameter PVC riser pipe and well screen (0.01 slot size). The monitoring points were set to screen the soil intervals with the maximum PID measurements. Screen lengths were 5 feet and all screens were set from 3 to 8 feet below ground surface (BGS) except for SVP-7 which required a deeper screened interval (9 to 14 feet BGS) to sample the interval beneath the building foundation.

The soil vapor monitoring points were field screened with a PID for the presence of VOCs and sampled on November 18, 2003. The PID readings ranged from background levels to 1.3 part per million (ppm). Soil vapor samples were collected from six of the seven monitoring points using 6-liter summa canisters with critical orifice flow controllers. Dedicated tubing was connected to each canister and inserted into the well headspace several feet below the top of the PVC riser. The canister vacuum was released and the canister was filled according to the manufacturer’s recommendations. A vapor sample was not collected from soil vapor monitoring probe (SVP-6) because, after consultation with NYSDEC, it was determined that an additional indoor ambient air sample from Building A would be collected in lieu of the soil vapor sample from SVP-6 (see Section 2.6.2.1, above).

Each canister was given a unique identification code and submitted under chain-of-custody procedures to the Columbia Analytical Services air laboratory in Simi Valley, California, for analysis of VOCs by EPA Method TO-15.


3.0 LAND USE AND PHYSICAL CONDITIONS OF THE SITE

As described in Section 2.0, the Site is comprised of several one-story buildings and parking areas encompassing 7.75-acres (Figure 2). The Site is located in the northwest portion of Long Island, in Glen Head, Nassau County, New York (Figure 1). The Site surroundings include the Long Island Railroad to the east, the Town of Oyster Bay equipment and road material storage yard to the northeast, a water storage tower owned by The Sea Cliff Water District to the south and residential areas to the north and west. Hempstead Harbor (Long Island Sound) is located approximately 1.5-miles to the west.

3.1 POPULATION DATA According to 2002 population data, Glen Head has approximately 4,638 residents. This represents a net increase of 125 residents from the 2000 count of 4,513. The population of Nassau County is 1,287,348 (1990 U.S. Bureau of the Census). Population in the county has declined since 1970.

3.2 SITE PHYSIOGRAPHY AND CLIMATE 3.2.1 Site Physiography The Town of Glen Head is located on a small ridge surrounded by slopes with regional grades ranging from 10 to 15% inland to 25% towards Hemstead Harbor (to the west). Figure 1 presents regional topographic features.

The Site topography is generally flat. The northern parking lot is graded with a slope to the east, allowing ground level access to the basement of Building H.

The majority of the Site is covered with asphalt or buildings. Small courtyards within the western portion of the Building E through H complex and the perimeter of driveways and parking lots are covered with landscaped grass and shrubs. The Site is accessed from Robert Lane on the western Site boundary. Fencing exists along the southern, eastern, and western Site boundary (with the exception of the driveway) of the Site. A wooded low lying area is present beyond the northern boundary.

3.2.2 Climate

The Site is located in the northwestern portion of Long Island, New York. The average precipitation is approximately 41.6 inches per year and average snowfall is approximately 23.3 inches per year (NOAA, 1998). Average temperatures range from 31.2 degrees Fahrenheit in


January to 75.5 degrees Fahrenheit in July (NOAA, 1998). The ground surface and Long Island Sound/Hempstead Harbor generally do not freeze in the winter. Winds are generally from the south with a mean velocity of 12 miles per hour (NOAA, 1998).

3.3 WATER SUPPLY The Site is served by the Sea Cliff Municipal Water District. The nearest water supply well (Well N-5792) is about one-half mile northeast of the Site and is owned by the Sea Cliff Water District. According to the District, this well is screened from 255 to 295 feet below grade and is pumped at an average rate of 900 gallons per minute.

3.4 SURFACE WATER 3.4.1 Storm Water As described in Section 2, the Site is relatively flat with surface water draining to a series of catch basins along the driveways and parking areas which act as dry wells and are identified as leaching pools on Figure 2.

3.4.2 Floodplain Areas There are no surface water bodies at or adjacent to the Site. The Hempstead Harbor is located approximately 1.5 miles to the west of the Site. Approximately 150 feet of relief occurs between the Site and Hempstead Harbor. The Site is not located within a 100-year flood plain (as defined by the Federal Emergency Management Agency (FEMA)).


4.0 GEOLOGY AND HYDROGEOLOGY

4.1 REGIONAL GEOLOGY AND HYDROLOGY The stratigraphy of Long Island generally consists of unconsolidated overburden deposits of clay, silt, sand and gravel overlying a Pre-Mesozoic Age schist and gneiss bedrock. Although some surficial weathering fractures exist, the bedrock in the region is of relatively low hydraulic conductivity and is generally considered to constitute the lower boundary of the regional groundwater flow system. The bedrock and overburden deposits slope to the southeast at approximately 65 feet per mile.

The overburden deposits are classified into three major geologic units. Descending from ground surface, the three units are the Pleistocene deposits (Upper Glacial Unit), the Magothy Formation and the Raritan Formation. The general hydrogeologic characteristics of each overburden unit are described below.

4.1.1 Pleistocene Deposits (Upper Glacial Unit) The Pleistocene deposits are comprised of stratified glacial outwash sediments. These deposits consist of medium to coarse sand and gravel with some discontinuous lenses of clay or silt. Regionally, the outwash deposits have a maximum thickness of approximately 100 feet. To the south of the Site, the outwash deposits form a significant unconfined waterbearing unit. The Upper Glacial waterbearing unit has a maximum thickness of approximately 100 feet. Horizontal hydraulic conductivity values ranging from 50 feet per day to 300 feet per day have been reported (Buxton et al., 1991). Franke and Cohen (1972) report a horizontal to vertical hydraulic conductivity anisotropy ratio of approximately 10:1 (Buxton and Modica, 1992; Smolensky and Feldman, 1988).

4.1.2 Magothy Formation The Magothy Formation is the primary source of potable and industrial water in Nassau County. The unit consists of fine to medium sand interbedded with discontinuous layers of coarse sand, silty clay, and clay. As a consequence, extreme heterogeneity may occur both horizontally and vertically. A coarse gravel unit approximately 100 feet in thickness reportedly exists at the base of the Magothy Formation forming a distinct interface between the Magothy Formation and the underlying Raritan Formation (Buxton and Modica, 1992). The maximum thickness of the Magothy Formation in the region is approximately 650 feet. Groundwater flow within this unit occurs under both unconfined and semi-confined conditions. The degree of confinement increases with depth primarily due to the effect of stratification and presence of


numerous silt and clay lenses. Average horizontal hydraulic conductivity values of approximately 50 feet per day have been reported for the upper portion of the Magothy Formation (Buxton and Modica, 1992). Average horizontal hydraulic conductivity values of 75 feet per day have been reported for the lower basal gravel (Buxton and Modica, 1992). The horizontal to vertical hydraulic conductivity ratio for the Magothy Formation has been estimated to be approximately 100:1 (Franke and Cohen, 1972).

4.1.3 Raritan Formation

4.1.3.1 Unnamed Clay Member An unnamed clay confining unit forms the upper member of the Raritan Formation. This unit is generally referred to in the literature as the Raritan Confining Unit. The confining unit consists of silty clay to clay with intermittent layers of sand. The confining unit has an average thickness of approximately 175 feet. The vertical conductivity of the confining unit has been estimated to be approximately 0.001 feet per day (Franke and Cohen, 1972). The confining unit sustains a significant hydraulic head difference between the Magothy Formation and the Lower Raritan Formation (Lloyd Sand Member). South of the Site, the hydraulic head difference is estimated to be approximately 20 to 30 feet (Franke and Cohen, 1972).

4.1.3.2 Lloyd Sand Member The Lloyd Sand forms the lower member of the Raritan Formation. The Lloyd Sand is a waterbearing unit consisting of fine to coarse sand with discontinuous layers of silt and clay. The waterbearing unit has a thickness of approximately 300 feet. An average hydraulic conductivity for the unit has been estimated to be approximately 40 feet per day with a horizontal to vertical hydraulic conductivity ratio of approximately 10:1 (Franke and Cohen, 1972).

4.1.4 Regional Groundwater Flow Figure 17 shows a generalized hydrogeologic cross-section oriented in a north-south direction through Nassau County. This cross-section provides a schematic representation of the regional groundwater flow system. Regionally, recharge occurs primarily through precipitation infiltration. An east-west oriented regional groundwater flow divide exists along the north central axis of the Long Island. North of the groundwater flow divide groundwater flows north toward Long Island Sound, which acts as a regional groundwater discharge zone. The Site is located north of the regional divide, hence groundwater flow across the Site is generally toward the north. South of the regional groundwater flow divide groundwater flows south toward the


Atlantic Ocean, which also acts as a regional groundwater discharge zone. Hydraulic gradients are generally downward in the vicinity of the regional groundwater flow divide and gradually become upward approaching the groundwater discharge zones along the shoreline of Long Island Sound and the Atlantic Ocean.

4.2 SITE GEOLOGY AND HYDROGEOLOGY In general, the soil samples obtained during drilling activities indicate the presence of fine to coarse sand and gravel deposits to depths of at least 150 feet bgs. Occasional silt and micaceous interbeds occur at depths below 60 feet bgs. Geophysical logs and soil sampling logs from the ERM investigation indicate silt and sandy silt interbeds, approximately 10 to 30 feet in thickness, are present at wells MW-1, MW-2, and MW-3. At depths below 140 to 150 feet bgs (at MW-7, MW-9, and MW-11) finer deposits of silt and sand occur with clay seams or lenses and traces of fine gravel. These finer deposits are characteristic of the sediments that comprise the Magothy Formation and may indicate a transition to the Magothy below the Site.

Groundwater at the Site was investigated in two monitoring intervals, designated the Upper Zone and the Lower Zone. The water table (top of the saturated zone) at the Site occurs between approximately 110 and 125 feet bgs. The Upper Zone is defined as the upper 10 feet of the saturated zone. The Lower Zone is defined as the 25 foot interval underlying the Upper Zone. The Upper and Lower Zone monitoring intervals do not represent hydraulically distinct units. Both are likely within the transition zone between the Upper Glacial Unit and the Magothy Formation. The Upper and Lower Zone monitoring intervals are designated in the RI solely for the purpose of investigating the vertical distribution of chemical presence in the upper 35 feet of groundwater.

The Upper Zone wells are screened across the water table and are approximately 120 feet deep. Hydraulic head measurements were obtained from all Upper Zone monitoring wells on November 15, 2002 and March 19, 2003 (Table 23). Figures 18A and 18B show the Upper Zone hydraulic head distributions prepared from the November 2002 and March 2003 measurements, respectively. Groundwater flows from high to low hydraulic head. As shown on Figures 18A and 18B, Upper Zone groundwater flow at the Site is indicated to be generally from south to north/northwest. This is consistent with the regional groundwater flow direction (see Section 4.1.4, above). The horizontal hydraulic gradient across the Site is approximately 0.002.


As described above, the Lower Zone monitoring wells monitor the saturated zone between approximately 125 and 150 feet bgs. Hydraulic head measurements were obtained from all Lower Zone monitoring wells on November 15, 2002 and March 19, 2003 (Table 23). Figures 19A and 19B show the Lower Zone hydraulic head distributions prepared from the November 2002 and March 2003 measurements, respectively. In general, Lower Zone groundwater flow is indicated to be northerly. However, there was a hydraulic high measured during November 2002 at MW-9 which could be indicative of a local westerly component of flow during this monitoring event. The horizontal hydraulic gradient is approximately 0.006.

Vertical hydraulic gradients calculated using the November 2002 measurements from paired Upper and Lower Zone wells are downward and ranged from 0.007 measured at monitoring well pair MW-3/MW-11 to 0.1 measured at monitoring well pairs MW-7/MW-8 and MW-3/MW-11. The smaller magnitude of the vertical hydraulic gradient at well pair MW-3/MW-11 is reflective of the hydraulic high measured in Lower Zone monitoring well MW-9 during this monitoring event. The March 2003 measurements show slightly upward vertical hydraulic gradients at monitoring well pairs MW-7/MW-8 and MW-3/MW-11.


5.0 CHEMICAL PRESENCE IN SITE MEDIA

This section presents the results of all sampling activities described in Section 2.0. These results together with past sampling results are used to characterize the nature and extent of chemical presence in soils, soil vapor, subsurface drainage structures, and groundwater at the Site.

The complete analytical data packages are included in Appendix G. All RI analytical results were validated by an independent company (Data Validation Services). Appendix F contains the Data Usability Summary Reports (DUSRs).

5.1 SOILS Soil samples collected and analyzed for the RI include Site background surface soil, Site surface soil and Site subsurface soil. The analytical results are presented below.

5.1.1 Background Surface Soil As described in Section 2.3.6, five background surface soil samples were collected along the western boundary of the Site at locations shown on Figure 11. The background locations were chosen to represent areas that do not receive runoff from the former operating portions of the Site or from the railroad tracks adjacent to the eastern boundary of the Site.

Analytical results for the background soil samples are presented in Table 8. No VOCs were detected. As shown on Figure 20, several SVOCs and metals were detected at concentrations typically encountered in urban environments with nearby vehicular traffic. The following chemicals were detected in background soils at concentrations above NYSDEC guidance values for soil cleanup (TAGM #4046):

Chemical #Detections/#Samples Maximum Concentration (mg/kg)

Benzo (a) anthracene 5/5 3.8 Chrysene 5/5 4.8 Benzo (b) fluoranthene 5/5 4.2 Benzo (k) fluoranthene 5/5 2.9 Benzo (a) pyrene 5/5 3.8 Dibenzo (a,h) anthracene 5/5 0.8 J (estimated) Arsenic 5/5 50.5 Cadmium 5/5 1.2 Copper 5/5 119 Mercury 5/5 0.59 Zinc 5/5 308


The organic chemicals listed above (benzo (a) anthracene, chrysene, benzo (b) fluoranthene, benzo (k) fluoranthene, benzo (a) pyrene, and dibenzo (a,h) anthracene) are a class of chemicals called polyaromatic hydrocarbons (PAHs). PAHs may be formed from fossil fuel combustion and are contained in particulate emissions from diesel and gasoline engines. The presence of PAHs in background soil samples is likely attributable to nearby vehicular traffic. The presence of metals in background samples is likely attributable to natural occurrence in soil and/or non Site-related anthropogenic sources such as vehicular emissions and residential use of pesticides and lawn chemicals (all background samples were at locations which could receive runoff from adjacent residential properties).

In the following subsections, chemical presence data for Site soils will be compared to the TAGM #4046 guidance values and to the Site background levels presented in Table 8.

5.1.2 Site Surface Soil

5.1.2.1 Remedial Investigation Results Table 9 presents all RI analytical results for Site surface soils with a comparison to TAGM #4046 guidance values. No VOCs were detected above the guidance values. The only VOC detected was acetone, which was reported in several samples at concentrations below the guidance value. Acetone is a commonly used laboratory chemical and its presence may be associated with laboratory contamination. The following chemicals were detected in Site soils at concentrations above the guidance values or Site background concentrations:

Chemical #Detections/#Samples Maximum Concentration (mg/kg)/Location Arsenic 22/22 86.6/Surf-22 Cadmium 22/22 6.2/Surf-22 Calcium 22/22 73,100/Surf-17 Chromium 22/22 305/Surf-22 Copper 22/22 418/Surf-22 Magnesium 22/22 42,900J(estimated)/Surf-17 Nickel 22/22 63.2/Surf-22 Zinc 22/22 1,450/Surf-22 Figures 21A and 21B present the distribution of chemicals measured in RI surface soil samples above the guidance values. In general, the highest chemical concentrations were measured in sample Surf-22. This sample is located at the rear (east) of Building E, adjacent to the railroad tracks.


5.1.2.2 Supplemental Remedial Investigation Results As indicated on Table 9, six surface soil locations sampled during the RI were found to contain one or more metals at concentrations above NYSDEC guidance values and/or background levels. These locations (shown on Figure 10) are designated Surf-15, Surf-16, Surf-17, Surf-19, Surf-20, and Surf-22. These locations were further investigated during September 2003 by collecting three additional samples from each area for TAL metals analysis. Sample identification numbers indicate the original RI sample identifier followed by a suffix of 1, 2 or 3 corresponding to the Supplemental RI sample number.

The analytical results for Site surface soil samples collected during the Supplemental RI are presented in Table 10. The following chemicals were detected at concentrations above the guidance values or Site background concentrations:

Chemical #Detections/#Samples Maximum Concentration (mg/kg)/Location Arsenic 3/18 161/Surf-22-1 Barium 1/18 895/Surf-15-1 Cadmium 7/18 9.3/Surf-22-1 Chromium 8/18 499/Surf-22-3 Copper 4/18 243/Surf-22-2 Mercury 1/18 0.69/Surf-16-3 Nickel 11/18 74/Surf-22-2 Zinc 5/18 1,580/Surf-15-1

These results are consistent with the RI results in that the highest chemical concentrations were generally measured in the samples surrounding RI sample location Surf-22.These results are further discussed in comparison to Site cleanup objectives in Section 8.2.

5.1.3 Subsurface Soil

5.1.3.1 Remedial Investigation Results Table 11 presents all analytical results for Site subsurface soils with a comparison to TAGM #4046 guidance values. Guidance values were exceeded in samples from two soil boring locations (RI-1 and RI-5, Figure 9). Arsenic was measured at 15.8 mg/kg in the 1 to 3 ft bgs sample collected from RI-1 (located between Buildings C and D). This concentration is below the Site background maximum of 50.5 mg/kg.

Several metals were measured at concentrations exceeding guidance values or Site background concentrations in the 0 to 2 ft bgs sample collected from RI-5. These include cadmium (15.5


mg/kg), chromium (269 mg/kg), copper (162 mg/kg), nickel (105 mg/kg), and zinc (205 mg/kg). Mercury was detected in this sample at a concentration of 0.56 mg/kg which is below the maximum background mercury concentration (0.59 mg/kg). The deeper sample from boring RI-5 (6 to 8 ft bgs) did not contain any metals above guidance values, but did contain TCE at a concentration of 2.1 mg/kg. The guidance value for TCE is 0.7 mg/kg. Soil boring RI-5 is located in the portion of Building G which was formerly housed degreasing and chrome plating operations.

The RI soil boring results indicate that soils below the buildings have not been impacted except for within the immediate vicinity of boring RI-5 located in the former plating and degreasing area.

5.1.3.2 Supplemental Remedial Investigation Results During the Supplemental RI, subsurface soil samples were collected from a soil boring located adjacent to Building A. The soil boring was advanced within 2 feet of the building wall (along its south side) to a depth of 20 feet. Field screening of the soil samples with a PID showed no measurable VOCs in any sample. The sample from the 10-12 foot depth interval was submitted for chemical analysis of TCL VOCs and TAL metals.

Results of the subsurface soil sampling adjacent to Building A are presented in Table 12. No VOCs or SVOCs were measured above detection limits in the subsurface soil sample. No metals were detected above the range of background concentrations.

5.2 SOIL VAPOR The results of soil vapor investigations conducted as part of the RI and Supplemental RI are presented in the following subsections. The Post-IRM soil vapor sampling program and results are presented in Section 7.4.

5.2.1 Remedial Investigation Results Table 13 presents the results of the soil vapor sampling from the six boreholes within which soil vapor monitoring points were installed. The chemical detected at the highest concentration in soil vapor was TCE (2,400 ug/m3 in soil boring RI-6). This boring is located within the portion of Building formerly used for degreasing operations. TCE was also detected at relatively elevated levels in three vapor monitoring points closest to RI-6 (RI-3, RI-7 and RI-9). The presence of TCE in soil vapor at these locations is not coincident with elevated presence of TCE in the soil matrix. It is therefore likely that the TCE present in soil vapor has migrated


laterally from a source located some distance from the soil borings. Groundwater is not likely to be the source as the water table is located approximately 100 feet bgs.

Based on the distribution of TCE in soil vapor (i.e., higher concentrations at RI-6), the sources of vapor phase VOCs detected in soils are likely the impacted subsurface drainage structures located near RI-6. Volatile chemicals (in the gaseous phase) are likely diffusing laterally through the soil beneath the buildings to the soil vapor monitoring points. Consequently, removal of impacted sediments from the subsurface drainage structures would be expected to reduce the VOC concentrations in soil vapor. Removal of these sediments was conducted as an IRM (See Section 7.0).

5.2.2 Supplemental Remedial Investigation Results The supplemental soil vapor monitoring probes are located throughout the south portion of the Site as shown on Figure 16. The analytical results from sampling these probes are presented in Table 14. The analytical data package is included in Appendix G. As expected, due to the proximity of these locations to the current and former dry cleaning operations located south of the Site, PCE was detected in all samples. Several other VOCs were detected generally at lower concentrations, most notably TCE, toluene, methyl tert-butyl ether (MTBE) and trichlorotrifluoroethane.

Measured PCE concentrations are summarized below and compared to the approximate distance from the soil vapor monitoring probe to the south property line (an indicator of relative proximity to the current or former dry cleaning operations).

Measured PCE Distance to Soil Vapor Probe Concentration (µg/m3) South Property Line (feet) SVP-1 100 45 SVP-2 2,200 20 SVP-3 270 120 SVP-4 3.0 90 SVP-5 78 210 SVP-6 Not Sampled 220 SVP-7 2,800 35 FS-1 * 47,000 10

Note: * Sampled September 2003


These results indicate the source of PCE presence in soil vapor is likely located to the south of the Site and would most likely be associated with current and/or former dry cleaning operations located off-Site in this area.

5.3 SUBSURFACE DRAINAGE STRUCTURES 5.3.1 IRM Investigation Sampling Program The analytical results for sediment samples from cesspools, leaching pools and drains are presented in Tables 15, 16, and 17 for VOCs, SVOCs, and metals, respectively. Table 6 lists the physical characteristics of each structure sampled. As shown on Figures 22A and 22B (VOCs), Figures 23A and 23B (SVOCs), and Figures 24A and 24B (Inorganic Metals), chemicals were measured in many of the sediment samples. As indicated on Table 6, most of the structures had concrete bottoms and insufficient sediment accumulation for collection of discrete, depth-specific samples.

Depth specific samples were collected from four drainage structures: LP-2, LP-20, LP-31A (SVOCs only), and LP-33. Results of analyses of these samples show the chemical presence is limited largely to the upper 1 foot of sediment. Sediment from LP-2 was sampled from 0 to 1 ft below top of sediment and from 1 to 2 feet below top of sediment. VOCs were present at concentrations up to 1,400 J (estimated) ug/kg (1,4-dichlorobenzene) in the upper foot of sediment from LP-2. No VOCs were present above detection limits in the 1 to 2 ft depth sample from LP-2. Depth-specific samples from LP-33 exhibited a similar decline in concentration with depth, although concentrations were lower than measured in LP-2.

Drainage structures LP-20 and LP-31A contained higher chemical concentrations in the upper sediment and exhibited even more precipitous declines in chemical concentrations with depth than observed in LP-2 and LP-33. As shown on Table 15, VOCs (primarily chlorobezenes) were measured at concentrations up to 250,000 ug/kg (chlorobenzene) in the upper foot of sediment from LP-20. In the deeper (1 to 3 ft) sample from the same structure only one chemical was detected: chlorobenzene at 6 ug/kg (estimated). This represents a reduction in concentration by a factor of more than 10,000 over approximately 2 feet in the sediment profile.

In accordance with the RI/FS Work Plan, samples from LP-31A were analyzed for SVOCs only. The chemicals detected at the highest concentrations in the upper 1 foot of sediment were PAH compounds at (estimated) concentrations up to 7,900 ug/kg. No chemicals were detected in the 1 to 2 ft depth interval.


The results discussed above indicate very little downward chemical migration has occurred within the subsurface drainage structures. To investigate potential horizontal migration from the structures, soil borings were advanced adjacent to the structures which based on prior investigations are the most highly impacted at the Site. Soil boring IRM-1 was advanced to a depth 16 feet adjacent to cesspool C-4. Soil boring IRM-2 was advanced to a depth of 28 feet adjacent to cesspool C-3.

During the November 2001 preaquisition investigation conducted by Geomatrix, sediment from cesspool C-4 was found to contain VOCs totaling 4,155,000 ug/kg. Soil boring IRM-1 was advanced adjacent to the east side of this structure. Samples were obtained for chemical analyses of VOCs from the 2 to 4 ft, 8 to 10 ft and 14 to 16 ft depth intervals from IRM-1. Analytical results are presented in Table 15. No chemicals were detected in samples from the 8 to 19 ft and 14 to 16 ft depth intervals. Two chemicals were detected in the 2 to 4 ft depth interval: acetone at 68J (estimated) ug/kg, and 2-butanone at 15 ug/kg. Both detections are below the associated soil cleanup guidance value for the substance. These results indicate little if any horizontal migration from cesspool C-4 has occurred.

During the November 2001 preaquisition investigation conducted by Geomatrix, sediment from cesspool C-3 was found to contain VOCs totaling 279,000 ug/kg. Soil boring IRM-2 was advanced adjacent to the west side of this structure. Samples were obtained for chemical analyses of VOCs from the 10 to 12 ft, 20 to 22 ft and 26 to 28 ft depth intervals. Analytical results are presented in Table 15. Acetone was the only chemical detected in the 10 to 12 ft depth interval (23 ug/kg). Acetone was also the only chemical detected in the 20 to 22 ft depth interval (11 ug/kg). Both acetone measurements are below the soil cleanup guidance value. No chemicals were detected in the lowermost interval (26 to 28 ft). These results indicate little if any horizontal migration from cesspool C-4 has occurred.

The results of the IRM sampling activities are consistent with the findings of previous sampling programs in that the chemical presence was found to be contained within the drainage structures and little migration from the structures has occurred.

5.3.2 Supplemental Remedial Investigation

5.3.2.1 Cesspool C-2 and Cesspool West of Building C The supplemental RI sampling of subsurface structures included sampling of cesspool C-2 (see Figure 2) and the cesspool found to be located west of Building C. Table 18 presents the results of the supplemental cesspool sampling. No chemicals exceeded TAGM #4046 guidance


values except for one exceedance in the cesspool west of Building C (mercury measured at 2.8 mg/kg).

5.3.2.2 Building A Septic System The results of the Building A septic system sampling are presented in Table 19. No chemicals were detected above TAGM #4046 guidance values in either the currently operating cesspool or the former septic tank. These results show that the current and historic Building A septic systems are not sources of the PCE measured in soil vapor (see Section 5.2.2) and indoor air at Building A (see Section 5.4).

5.4 AMBIENT AIR (BUILDING A) Table 20 presents the results of ambient air sampling at Building A. Ambient air results were compared to USEPA Region 9 Preliminary Remediation Goals (PRGs) and NYSDEC Short-Term Guideline Concentrations (AGCs). PCE exceeded one or more of these limits in all three samples. Measured concentrations were as follows:

PCE Concentration (µg/m3)

Building A Soil Gas 47,000

Building A Ambient Indoor (Basement) 99

Building A Ambient Outdoor 16

Ethylbenzene was measured in the Building A indoor ambient air sample at a concentration of 4 µg/m3, which exceeds the USEPA Region 9 PRG of 1.7 µg/m3. No other chemicals exceeded these limits.

Results of the subsurface soil sampling adjacent to Building A are presented in Table 12. No VOCs or SVOCs were detected in the subsurface soil sample collected adjacent to Building A (see sample FS-1). No metals were detected above the range of background concentrations.

Taken together, the PCE analytical results of the Building A sampling indicate the following. The elevated PCE concentration measured in soil vapor adjacent to Building A (see sample FS-1, Section 5.2.2, above) suggests a residual presence of PCE relatively high up in the unsaturated zone, indicating a release point nearby. The lack of PCE in the subsurface soil sample suggests the release did not occur at Building A. Furthermore, the PCE detection in outdoor ambient air suggests that PCE use and emission may be an ongoing occurrence at dry


cleaning operations near the Site and is effecting ambient air quality. Finally, the results of the Building A septic system investigation (Section 5.3.2.2) confirm that past or present activities at Building A are not the source of PCE measured in soil gas and ambient air.

The NYSDEC Preliminary Site Assessment Report for the regional groundwater plume shows Building A is located directly north of the location of a former unnamed dry cleaning establishment and within a few hundred feet of several other former of current dry cleaning operations. While any of these could be a source of PCE measured in soil vapor, based on its proximity, the former dry cleaning operation located adjacent to Building A (corner of Dumond Place and Glen Head Road) is the more likely source of PCE measured in soil vapor. Any of the ongoing operations could be a source of continuing emissions.

5.5 GROUNDWATER 5.5.1 Upper Zone Groundwater Table 21 presents the results of analyses of groundwater samples collected in November 2002 from Upper Zone monitoring wells (including NYSDEC MW-7), and compares the detected results to New York State Groundwater Criteria for Class GA Groundwater (Class GA Criteria). As with previous groundwater sampling events (see Section 1.2), the primary chemical of potential concern (COPC) in groundwater is PCE. Figure 25 depicts the chemical distributions in Upper Zone groundwater based on the results of the November 2002 sampling event and includes the distribution based on the 1996 sampling event for comparison. Results show most chemical concentrations in on-Site groundwater have decreased by 50 percent or more compared to the 1996 results.

The following inorganic parameters exceeded Glass GA Criteria: iron, manganese, nickel (one sample) and sodium. None of these exceedances are believed to be related to past or present activities at the Site and likely reflect regional groundwater conditions.

As discussed in Section 1.2, groundwater quality in the Glen Head area has been impacted by apparent spillage of dry cleaning chemicals at current or former dry cleaning establishments in the Town. The chemicals attributable to the dry cleaners are PCE and degradation products including TCE. The Site may also have contributed some TCE to groundwater, however, the amount appears to be small compared to the amount of chemicals already present in Upper Zone groundwater flowing onto the Site.


Based on the Upper Zone hydraulic head distribution presented in Section 4.2, MW-8 is a downgradient Site monitoring well in the Upper Zone. VOCs were not detected in MW-8. This indicates no significant off-Site migration of COPCs is occurring from this portion of the property. However, a portion of the groundwater from the southern areas of the Site may flow off-Site to the northwest prior to reaching MW-8 Therefore, MW-8 may not be representative of all groundwater flowing off the Site.

5.5.2 Lower Zone Groundwater Table 22 presents the results of analyses of groundwater samples collected in November 2002 from Lower Zone monitoring wells, and compares the detected results to the Class GA Criteria. The only chemical detected above Class GA Criteria is PCE. Measured PCE concentrations were 12 ug/L in upgradient monitoring well MW-11, and 8J ug/L in Site monitoring well MW-9. As described above, the PCE measured has likely migrated to the Site from one or more upgradient sources.

Figure 26 depicts the chemical distributions in Lower Zone groundwater based on the results of the November 2002 sampling event and includes the distribution based on the 1996 sampling event for comparison. In the downgradient Lower Zone monitoring well (MW-7), only one chemical was detected (methyl tert-butyl ether at an estimated concentration (below the Class GA Criteria) of 3 ug/L. The results of the Lower Zone sampling indicate no significant off-Site migration of COPCs is occurring.


6.0 QUALITATIVE HUMAN HEALTH EXPOSURE ASSESSMENT

The qualitative exposure assessment consists of characterization of the exposure setting (including the physical environment and potentially exposed human populations), identification of exposure pathways, and evaluation of contaminant fate and transport.

6.1 POTENTIAL CHEMICAL TRANSPORT PATHWAYS As described in Section 5.0, COPCs were detected in Site surficial soils, subsurface soils, subsurface drainage structures, soil vapor, and groundwater. In general, potential transport pathways for these chemical constituents may involve:

• Volatilization, transport in air

• Wind erosion, transport in air

• Water erosion, transport in surface water runoff/storm sewer water

• Transport in groundwater

Potential transport pathways are described in more detail below.

6.1.1 Airborne Pathways Potential migration pathways involving airborne transport include:

• Wind erosion and transport of soil particles and sorbed chemical constituents in fugitive dust emissions.

• Volatilization of chemical constituents from surface soils, subsurface soils, and/or subsurface drainage structures and subsequent atmospheric dispersion.

6.1.1.1 Fugitive Dust The Site is almost completely paved and covered with buildings. The small areas of the Site not paved or covered by buildings are well vegetated. Results of the surficial soil sampling program showed the Site surficial soils to be similar to the background samples in most cases and typical of urban soils in all cases. Consequently, fugitive dust emissions are not considered a potentially significant transport pathway for Site-related constituents.

6.1.1.2 Volatilization Volatile chemical constituents present in Site media could volatilize to the atmosphere and be transported off-site. For surface soils, volatilization of chemicals (if present) would be more or


less direct into the atmosphere. For subsurface soils, volatilized constituents would have to diffuse through the overlying soil prior to reaching the atmosphere where off-site transport could occur.

Except for acetone, which was detected in several samples at concentrations well below the TAGM #4046 Guidance Value, surface soil samples did not contain any measurable concentrations of VOCs. VOC detections in subsurface soil were also quite low with only one of 29 subsurface soil samples containing a VOC above its Guidance Value. The single exceedance occurred for TCE in the 6 to 8 feet bgs depth interval sample from boring RI-5. The measured concentration was 2,100 ug/kg versus the Guidance Value of 700 ug/kg. The overlying sample at this location (0 to 2 ft bgs) with a TCE concentration of 15 ug/kg was well below the Guidance Value. Based on these analytical results for surface and subsurface soil samples, volatilization from surface and subsurface soils does not result in significant chemical migration off-Site in air.

As described in Section 5.2, the soil vapor sampling showed that chemicals present in the soil vapors were associated the nearby subsurface drainage structures rather than soil contamination or volatilization from groundwater.

6.1.3 Waterborne Pathways Chemicals could potentially migrate from the Site in surface water runoff and groundwater.

6.1.3.1 Surface Water Runoff Erosion and transport of surface soils and associated sorbed chemicals in surface water runoff is a potential migration pathway for the Site. As described above, results of the surficial soil sampling program showed the Site surficial soils to be similar to the background samples in most cases and typical of urban soils in all cases. Furthermore, runoff from the Site is collected in the subsurface drainage structures and recharged to groundwater. Off-site transport in surface water is therefore not considered to be a significant migration pathway.

6.1.3.2 Groundwater Transport Groundwater flow at the Site occurs generally from south to north. The furthest downgradient wells (MW-7 and MW-8) do not show significant chemical presence. This indicates that significant off-Site migration in groundwater is not occurring from this area. As discussed in Section 5.5, it is uncertain whether MW-7 and MW-8 adequately represent all groundwater


which may be flowing off the Site and therefore additional investigation is recommended (see Section 8.3).

On-Site groundwater is not used for water supply. Future development plans for the Site do not contemplate development of an on-Site water supply.

6.2 EXPOSURE PATHWAY ASSESSMENT As described above (and with the caveat that groundwater will be further investigated), there are no significant pathways through which chemicals present at the Site are currently being transported off-Site at significant rates. Therefore, potentially complete exposure pathways under the current land use are limited to direct contact with on-Site sediment within the subsurface drainage structures, and inhalation of VOCs apparently migrating from the subsurface drainage structures to indoor air. The potentially exposed population for the former pathway would be personnel involved in cleaning or maintenance of the subsurface drainage structures.

The potentially exposed population for the latter would be workers in the Site buildings. However, the maximum chemical concentration in soil vapor measured in 2002 during the RI (TCE at 2.4 mg/m3) is several orders of magnitude below the National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 25 ppm (134 mg/m3) and would not result in buildup of unacceptable concentrations in building indoor air. The increases in soil vapor concentrations measured in 2003 after completion of the IRM and followup indoor air measurements are discussed in Section 7.4.

The potential sources of chemical diffusion into indoor air will be removed when the subsurface drainage structures are cleaned during the remediation of the Site (see Section 8.0).


7.0 INTERIM REMEDIAL MEASURE (SEPTEMBER 2003)

The IRM was conducted at the Site in September 2003. Prior to beginning the work, a fact sheet describing the planned activities was prepared by NYSDEC and mailed to the residents and other interested parties in the vicinity. The IRM consisted of cleaning six underground structures at the Site. The work performed was in accordance with the approved IRM Work Plan (contained within the RI/FS Work Plan).

7.1 IRM OBJECTIVES The IRM objectives were both remedial and investigative. The remedial objective was to clean the structures, remove the contaminated sediment and, for the open bottom structures, to remove underlying soil which may be impacted. The investigative objective was to verify the feasibility of remediating the structures using the methodology specified in the IRM Work Plan and to evaluate the depth to which soil underlying the open bottomed structures may be impacted.

7.2 IRM WORK PERFORMED As described in the correspondence from Geomatrix to NYSDEC dated July 25, 2003 the IRM originally was planned to address five underground structures. Locations of these structures, designated C-3, C-4, C-5, LP-3 and LP-11, are shown on Figure 27. During the course of the work, it was determined that structure LP-2 (see Figure 27) was connected to structure C-5 (its water level dropped in response to pumping from C-5). Therefore, following notification to NYSDEC, structure LP-2 was added to the list of structures to be remediated during the IRM.

The methods used to clean the structures were as described in the IRM Work Plan. A representative of the Nassau County Health Department (NCHD) was on-Site during the work and collected split samples of the excavation endpoints. The work performed is described in detail as follows.

Before conducting any IRM activities the liquid contained within the structures was sampled and analyzed for corrosivity, VOCs (Method 8260), and NCDH Metals. The analytical results were submitted the Nassau County Department of Public Works (NCDPW) to obtain approval for treatment of the liquid at the Bay Park Scavenger Waste Disposal Facility. The liquid was approved by the NCDPW for treatment by letter dated August 29, 2003. Prior to removal of accumulated sediments, the liquid contained within each structure was pumped and transported to the aforementioned treatment facility for treatment and disposal.


The approximate dimensions of the remediated structures are as follows:

Structure ID Dimensions Pre-Excavation Depth

C-3 4 feet by 4 feet square 7 feet

C-4 4 feet by 4 feet square 4 feet

C-5 8 feet diameter 18 feet

LP-2 8 feet diameter 17 feet

LP-3 36 inch by 30 inch rectangular 3 feet

LP-11 8 feet diameter 17 feet

Inspection of structures C-3 and C-4 after the liquid was removed revealed them to be a single structure with two manholes. The interior of the structure contained a concrete baffle. The bottom sludge residue was vacuumed out revealing a solid concrete bottom to the structure. The concrete bottom was verified by the NCDH representative and no endpoint samples were required. Approximately 4800 gallons of liquid and 4 feet of sludge/sediment were removed.

Structure C-5 is a leaching pool for C-3 and C-4. As indicated above, during pumping of the liquids in C-5, a decline in the liquid level in LP-2 was observed. A total of 9,600 gallons was removed from C-5 and LP-2. After pumping, a pipe connecting the two structures was clearly observed. Structures C-5 and LP-2 were remediated as follows. The vacuum truck was used to remove several feet of sludge and wet sediment from each structure. An “orange peel dredge” was then used to excavate approximately 4 feet of sediment from each structure. In structure C-5, concrete blocks were encountered while excavating below the sludge layer. The presence of these blocks accounts for the false refusal previously reported during the RI (C-5 was misreported to be solid bottom structure, see Table 6). Soil within each structure was excavated until the removed soil was free of staining and odors. The dredge was then decontaminated by washing with detergent and water and used to collect the endpoint samples. Endpoint samples were split with the NCHD representative. The samples were analyzed for TCL VOCs, TCL SVOCs, and TAL Metals.

Structure LP-3 contained approximately 2.5 to 3 feet of sediment which was removed using the vacuum truck, revealing a solid concrete bottom. The structure was washed and cleaned and no endpoint samples were required.


Structure LP-11 is an open bottom leaching pool. Approximately 9,600 gallons of liquid were removed and transported to the treatment plant. Using the vacuum truck and dredge, approximately 6 feet of sediment was removed after which the material encountered was free of stains and odors. The dredge was subsequently decontaminated and used to collect the endpoint sample. As with the other open bottom structures remediated, the endpoint samples were split with the NCDH representative and analyzed for TCL VOCs, TCL SVOCs and TAL Metals.

All sludge, sediment, and soil removed from the structures was contained within lined 20 cubic yard roll-off containers and stored at the north end of the property. Waste characterization samples were collected and the material was disposed at an approved facility.

7.3 ENDPOINT SAMPLE RESULTS Table 24 presents the analytical results for the endpoint sample analyses. No VOCs, SVOCs or TAL metals were present in the samples at levels exceeding the cleanup objectives (see Section 8.2.3). This indicates the structures were successfully remediated.

7.4 POST-IRM SOIL VAPOR AND AMBIENT AIR SAMPLING After completion of the IRM, the soil vapor probes installed within the main building complex were sampled on three occasions. In addition, two ambient air indoor samples and one ambient outdoor air sample were collected.

7.4.1 Post-IRM Soil Vapor Sampling On September 10, 2003 a second round of soil vapor samples was collected from the soil vapor monitoring probes shown on Figure 12. These soil vapor samples were collected less than one week after the IRM was completed. Samples were analyzed for VOCs by EPA Method TO-15. Sample collection and analytical methods were in accordance with the RI/FS Work Plan. As expected, the analytical results, shown on Table 25, show higher detections of TCE than the samples collected in November 2002 (compare with Table 13). This suggests the combination of the removal of liquids and disturbance/agitation of sludge and sediment during the IRM caused volatilization of TCE and other VOCs which subsequently diffused under the building slab (possibly along preferential pathways associated with the building sewer system which connects directly to the remediated structures). This “spike” in concentration following the IRM supports the RI conclusion that the presence of TCE in soil vapor was attributable to vapor phase migration from the cesspools and leaching pools.


On November 18, 2003, approximately 10 weeks after completion of the IRM (cleanout of selected cesspools/leaching pools), a round of soil vapor samples was collected from the soil vapor monitoring probes. Sample collection and analytical methods were as described above. The results of this sampling event are presented in Table 26. As with the prior sampling event, TCE was the chemical detected at the highest concentrations, although at levels substantially lower than measured on September 10, 2003.

Selected soil vapor probes (RI-3, RI-6 and RI-7) were resampled on June 17, 2004 in accordance with Geomatrix letter to NYSDEC dated June 16, 2004. These samples were analyzed specifically for the following chemicals which had previously been measured at elevated concentrations in soil vapor samples: PCE, TCE, 1,1,1-trichloroethane and cis-1,2-dichloroethene using EPA Method TO-14A. Analytical results are presented in Table 27. Concentrations measured in these samples were approximately the same as levels measured for the September 2003 sampling event.

In soil vapor samples from all three events, TCE was the chemical present at the highest concentration. The TCE concentrations for all post-IRM events are compared below with results obtained during the RI conducted prior to the IRM:

TCE Concentration in µg/m3 Remedial Investigation Samples Post-IRM Samples Location 11/18/02 9/10/03 11/18/03 6/17/03

RI-3 130 160,000 47,000 230,000 RI-6 2,400 200,000 36,000 100,000 RI-7 1,200 150,000 81,000 190,000 RI-9 53 99,000 22,000 NS RI-11 8.4 670 380 NS RI-15 ND 42 31 NS Notes: ND = Not Detected NS = Not Sampled

These results suggest that some of the VOCs which vaporized during the IRM process may have become trapped beneath the building slab and are not readily dissipating. It is also possible that small quantities of impacted sediment or sludge may have been introduced to the sanitary piping during the IRM. Considering the latter possibility, the final remediation of the subsurface drainage structures should be performed to minimize this potential occurrence. If


this is not feasible, the sanitary pipes should be flushed or removed after the subsurface structures are cleaned out.

7.4.2 Post-IRM Ambient Air Sampling On June 17, 2004, ambient indoor air samples were collected from two locations in the main building complex: one from the hallway between locations RI-6 and RI-7; and one from the office area west of location RI-11 (See Figure 12). In addition, an outdoor ambient air sample was collected from the rear of the building (near soil vapor probe RI-6). Ambient air samples were analyzed for PCE, TCE, 1,1,1-trichloroethane and cis-1,2-dichloroethene using EPA Method TO-14A. The analytical results for these samples are presented in Table 28.

In the ambient indoor air samples, TCE was the chemical present at the highest concentrations (36 ug/m3 and 290 ug/m3). These concentrations are more than 1,000 times lower than the Occupational Safety and Health Administration (OSHA) 8-hour time weighted average concentration for TCE of 537,000 ug/m3. Consequently, these levels do not likely pose a concern for the businesses currently leasing space at the Site.

PCE was the only chemical detected in the outdoor ambient air sample taken from the rear (east) of the main building complex opposite the location of soil vapor probe RI-6. The measured concentration was 1.6 ug/m3. This concentration is likely representative of the background ambient outdoor PCE concentration at this location. Note that PCE measured in the ambient outdoor sample collected at Building A (located adjacent to the former dry cleaning Site and nearer to the operating dry cleaners) is approximately three times higher (5.1 ug/m3).

7.5 IRM CONCLUSIONS The results of the endpoint sampling demonstrate the feasibility and effectiveness of using the methods described above to remediate impacted subsurface structures at the Site. The structures remediated during the IRM were the most highly contaminated at the Site and excavation depths required were approximately 6 feet below the top of the sediment. Therefore, it is anticipated that similar or lesser excavation depths will be necessary during remediation of the remaining impacted structures.

Precautions to prevent potential impact to sanitary piping and/or post-remediation removal or cleaning of sanitary piping may be necessary when conducting future remediation of subsurface drainage structures. Site remediation is further discussed in Section 8.0.


8.0 SITE REMEDIATION

This Section describes the designation of Operable Units to be remediated and presents the Remedial Action Objectives (RAO) for the Site. Remediation of each Operable Unit will be addressed in a Feasibility Study to be developed based in part on the findings of this RI.

8.1 OPERABLE UNITS In a letter dated June 25, 2004, NYSDEC determined that for remediation purposes the Site will be separated into two Operable Units. Operable Unit 1 (OU-1) covers the soils to be remediated and includes surface soils and sediment and subsurface soils associated with the subsurface drainage structures. Operable Unit 2 (OU-2) refers to Site groundwater and groundwater which may have been impacted by the Site.

Remedial Action Objectives (RAOs) have been developed for OU-1 (see Section 8.2). Additional sampling and investigation is recommended prior to developing RAOs for OU-2 (see Section 8.3).

8.2 REMEDIAL ACTION OBJECTIVES FOR OU-1 The RAOs described below are based on the assumption that the future use of the Site will be residential.

8.2.1 Exposure Pathway and Transport Considerations The qualitative exposure assessment identified two potentially complete exposure pathways at the Site. Both potentially complete pathways involved the subsurface drainage structures at the Site. Sewer workers could be exposed to sediments within the cesspools and leaching pools during maintenance activities and building occupants could be exposed to volatile chemicals diffusing from the subsurface structures through the soil into the buildings. A third potentially complete pathway was identified by NYSDEC in their review of the draft RI Report--potential direct contact with surface soils. The Site RAOs will therefore address the potential exposure to chemicals in both the subsurface structures and the Site surface soils.

The RI found that Site groundwater has been impacted by PCE released upgradient of the Site in the Town of Glen Head. The presence of TCE, a degradation product of PCE, in Site groundwater may be attributable to the upgradient source. However, TCE appears to have been released to the subsurface drainage structures at the site. It is possible that past migration from the impacted structures could have contributed to the observed groundwater impacts at the Site.


However, the potential impact on groundwater of any TCE released at the Site would be relatively minor compared to the regional impacts from upgradient releases of PCE. The small area of TCE presence which could (conceivably) be attributed to the Site is entirely contained within a far larger plume containing higher concentrations of PCE and its degradation products (e.g. TCE and 1,2-dichloroethene).

NYSDEC, in a letter to Geomatrix dated September 15, 2003, requested that the issue of groundwater contamination at and downgradient of the Site be addressed in a Feasibility Study. To provide additional data for the Feasibility Study, some additional groundwater investigation is recommended (see Section 8.3).

8.2.2 Remedial Action Objectives for Surface Soils As described in Section 2.3, a background surface soil sampling program was conducted at the Site as part of the RI. Background sample analytical results were statistically analyzed to obtain representative background values in accordance with Section 1.6.2 of the NYSDEC Technical Guidance DER-10. The results of the statistical analyses of background soil results were submitted to NYSDEC in a letter from Geomatrix dated August 14, 2003 and were approved by NYSDEC in a letter dated September 15, 2003. The results of the statistical analyses are summarized below.

Utilizing the statistical methodology from NYSDEC Technical Guidance DER-10, the following representative background values are calculated:


Chemical 75th Percentile (Natural Log)

25th Percentile (Natural Log)

Outlier Value (Natural Log)

Outlier Value Concentration

Representative Background Value (1)

Benzo(a)anthracene 6.23 5.63 7.13 1254 µg/kg 510 µg/kg Chrysene 6.58 6.23 7.10 1208 µg/kg 720 µg/kg Benzo(b)fluoranthene 6.55 6.19 7.09 1195 µg/kg 700 µg/kg Benzo(k)fluoranthene 6.09 5.74 6.61 744 µg/kg 440 µg/kg Benzo(a)pyrene 6.38 5.97 7.00 1098 µg/kg 590 µg/kg Dibenzo(a,h)anthracene 4.94 4.44 5.69 296 µg/kg 140 µg/kg Aluminum 9.17 9.00 9.43 12460 mg/kg 11500 mg/kg Arsenic 2.98 2.03 4.41 82 mg/kg 50.5 mg/kg Cadmium 0.00 -1.14 1.71 6 mg/kg 1.2 mg/kg Calcium 8.00 7.44 8.85 6974 mg/kg 4000 mg/kg Chromium 2.93 2.73 3.22 25 mg/kg 19.1 mg/kg Copper 4.53 3.72 5.74 311 mg/kg 119 mg/kg Iron 9.66 9.24 10.28 29077 mg/kg 17000 mg/kg Lead 4.77 4.37 5.37 214 mg/kg 145 mg/kg Magnesium 7.58 7.27 8.03 3073 mg/kg 2170 mg/kg Manganese 5.86 5.69 6.10 448 mg/kg 421 mg/kg Mercury -1.20 -2.21 0.30 1 mg/kg 0.59 mg/kg Potassium 6.28 6.02 6.68 792 mg/kg 707 mg/kg Zinc 5.61 4.39 7.44 1702 mg/kg 308 mg/kg Notes: (1) Highest concentration in background samples after outliers are excluded.

For the chemicals detected in soil background samples (listed above), the calculated representative background sample will be used as the surface soil cleanup objective. For chemicals not detected in the background samples (including all VOCs), the TAGM #4046 guidance values will be used as the surface soil cleanup objectives. Tables 29A and 29B list the cleanup objectives for surface soils and identifies whether the value is a representative background concentration or TAGM #4046 guidance value.

The RAO for surface soil will be to prevent exposure via direct contact to any surface soils exceeding the cleanup objectives presented in Tables 29A and 29B. Figure 28 depicts the areas where surface soil sample results exceed the RAOs.

8.2.3 Remedial Action Objectives for Subsurface Structures

The organic chemical concentrations listed in Table 29A will also be applied to cleanup of the subsurface drainage structures. The Nassau County Department of Health (NCDH) was contacted for a recommendation on metals cleanup levels. The NCDH is responsible for overseeing closure of similar structures throughout Nassau County. According to Mr. Lovejoy


of NCDH, the Department uses the cleanup levels listed in Table 29C for metals in cesspools and leaching pools. These levels will be used as the cleanup objectives for metals in subsurface structures.

The feasibility of attaining these objectives was demonstrated during the IRM.

8.3 RECOMMENDED ADDITIONAL INVESTIGATIONS FOR OU-2 Groundwater flow at the Site occurs generally from south to north/northwest. The furthest downgradient wells (MW-7 and MW-8) do not show significant chemical presence. This indicates that significant off-Site migration in groundwater is not occurring from this area. However, as indicated in Section 5.5, it is uncertain whether downgradient wells MW-7 and MW-8 are representative of all groundwater flowing off the Site. Therefore, additional characterization of the groundwater regime is recommended. This may entail additional sampling of existing wells on the Site and/or sampling of groundwater northwest of the existing Site wells. A work plan for the supplemental investigations of OU-2 will be submitted to NYSDEC under separate cover.


9.0 SUMMARY OF CONCLUSIONS

The findings of the RI are summarized as follows:

9.1 SURFACE SOILS Chemical concentrations in surface soils at the Site are generally not substantially elevated compared to Site background samples and/or typical urban surface soil concentration levels. Areas where these levels were exceeded were relatively localized. RAOs were developed to address surface soils in these areas. Areas where surface soil samples were found to exceed the RAOs are depicted on Figure 28.

9.2 SUBSURFACE SOILS Chemical concentrations in subsurface soil beneath Site buildings and adjacent to underground drainage structures are not elevated.

9.3 SUBSURFACE DRAINAGE STRUCTURES The results of the IRM sampling showed elevated levels of chemicals in a number of cesspools and leaching pools located throughout the Site. The results of the IRM sampling activities are consistent with the findings of previous sampling programs in that the chemical presence was found to be contained within the drainage structures and little migration from the structures has occurred.

The IRM was completed in September 2003 and entailed cleaning six of the most impacted subsurface drainage structures. The results of the IRM endpoint sampling demonstrate the feasibility and effectiveness of using the methods described in this report to remediate impacted subsurface structures at the Site. Therefore it is recommended that structures which have been found to contain constituents in sediment above the RAOs (identified in Section 8.2.3) be remediated using the IRM procedures.

The structures remediated during the IRM were the most highly contaminated at the Site and excavation depths required were approximately 6 feet below the top of sediment. Consequently, it is anticipated that similar or lesser excavation depths will be necessary during remediation of the remaining impacted structures.


Precautions to prevent potential impact to sanitary piping and/or post-remediation removal or cleaning of sanitary piping may be necessary when conducting future remediation of subsurface drainage structures (see Section 9.4, below).

9.4 SOIL VAPOR Soil vapor samples obtained from beneath the Site buildings during the RI sampling in 2002 contained detectable levels of VOCs (including TCE). However, these concentrations measured are relatively low and do not pose a hazard to indoor air quality. The lack of elevated VOC concentrations in the co-located soil matrix samples suggest the detected compounds diffused to the sample point from somewhere else. The proximity of the soil vapor sampling points in which VOCs were detected to the impacted subsurface drainage structures suggests the source(s) of VOCs measured in the soil vapor is(are) the nearby cesspools and/or leaching pools and not the soil underlying the buildings.

Immediately after completion of the IRM which entailed cleaning six of the most impacted subsurface drainage structures, soil vapor concentrations beneath the main building complex increased by more than an order of magnitude. These results suggest that some of the VOCs which vaporized during the IRM process may have become trapped beneath the building slab and are not readily dissipating. It is also possible that small quantities of impacted sediment or sludge may have been introduced to the sanitary piping during the IRM. Considering the latter possibility, the final remediation of the subsurface drainage structures should be performed to minimize this potential occurrence. If this is not feasible, the sanitary pipes should be flushed or removed after the subsurface structures are cleaned out.

The investigation of soil vapor concentrations in the south portion of the Site indicates that PCE presence in soil vapor is likely attributable to lateral vapor phase migration from one or more off-Site sources located south of the Site. The off-Site source(s) would most likely be associated with current and/or former dry cleaning operations located in this area. Of these Sites, the closest is the former dry cleaning operation which was located at the corner of Dumond Place and Glen Head Road within 25 feet of Building A.

9.5 BUILDING A The results of the investigations presented in this report show that past or present activities at Building A are not the source of PCE measured in soil gas and ambient air. The probable off-Site source(s) are identified in Section 9.4, above. Remediation of these off-Site sources is not the responsibility of TransTechnology Corporation.


9.6 GROUNDWATER Groundwater flow at the Site occurs generally from south to north/northwest. The furthest downgradient wells (MW-7 and MW-8) do not show significant chemical presence. This indicates that significant off-Site migration in groundwater is not occurring from this area. It is uncertain whether MW-7 and MW-8 are representative of all groundwater flowing off the Site as some groundwater may flow off-Site to the south of these wells. Additional investigation of the potential for off-Site groundwater flow to the south of wells MW-7 and MW-8 is recommended to address this uncertainty. A work plan for these additional investigations will be submitted to NYSDEC under separate cover.

On-Site groundwater is not used for water supply. Future development plans for the Site do not contemplate development of an on-Site water supply.

The RI confirmed the results of the NYSDEC Preliminary Site Assessment Report for the Glen Head Groundwater Plume (September 2000) which showed that Site (and regional) groundwater has been impacted by apparent spillage of dry cleaning chemicals at current or former dry cleaning establishments located upgradient of the Site in the Village of Glen Head. The chemicals attributable to the dry cleaners are PCE and degradation products including TCE. The Site may also have contributed some TCE to groundwater, however, the amount appears to be small compared to the amount of chemicals already present in Upper Zone groundwater flowing onto the Site. Comparison of the results of chemical analyses of groundwater with results from the 1996 sampling suggest the chemical presence in groundwater at the Site has declined.

Any potential impact on groundwater associated with TCE release at the Site would be relatively minor compared to the regional impacts from the upgradient releases of PCE. The small area of TCE presence which could (conceivably) be attributed to the Site is entirely contained within the far larger regional plume which contains higher concentrations of PCE and its degradation products (e.g. TCE and 1,2-dichloroethene). Therefore, in order to successfully and permanently remediate the TCE presence at the Site (regardless of its source), the inflow of contaminated groundwater to the Site from the upgradient off-Site sources would have to be eliminated.

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