bountiful/woods cross/5th south pce plume npl site · 2.3 scope and role of operable unit or...

SDMS Document ID

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RECORD OF DECISION

BOUNTIFUL/WOODS CROSS/5TH SOUTH

PCE PLUME NPL SITE

Operable Unit 1

BOUNTIFUL, DAVIS COUNTY, UTAH

PREPARED BY:

U.S. ENVIRONMENTAL PROTECTION AGENCYREGION 8

DENVER, COLORADO

September 2006

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCE Plume NPL Site - Operable Unit 1 September 2006

Table of Contents

THE DECLARATION. 1

1.1 Site Name and Location 1

1.2 Statement of Basis and Purpose 1

1.3 Assessment of OU1 1

1.4 Description of Selected Remedy 1

1.5 Statutory Determinations 2

1.6 Data Certification Checklist 3

1.7 Authorizing Signatures 3

THE DECISION SUMMARY. 5

2.0 Site Name, Location, and Brief Description 5

2.1 OU1 History and Enforcement Activities 52.1.1 Site History and Land uses 52.1.2 Previous Investigations and Actions Taken At OU1 6

' 2.1.3 Remedial Investigation/Feasibility Study, 2001-2006 72.1.4 Ecological Risks 82.1.5 Enforcement Activities 8

2.2 Community Participation 9

2.3 Scope and Role of Operable Unit or Response Action 10

2.4 Summary of OU1 Characteristics 112.4.1 Conceptual OU1 Model 112.4.2 Overview of OU1 122.4.3 Geology : 122.4.4 Hydrogeology 132.4.5 Sampling Strategy 132.4.6 Known and/or Suspected Sources of Contamination 14

2.5 Types of Contamination and Affected Media 142.5.1 Surface Soil : 142.5.2 Sub-surface Soil 142.5.3 Suspected Secondary Source 15

2.6 Groundwater 152.6.1 Permanent Monitoring Wells 152.6.2 Domestic Wells 162.6.3 Municipal well - West Bountiful 5dl South Well 162.6.4 Groundwater Contamination 16

2.7 Location of Contamination and Migration 182.7.1 Lateral and Vertical Extent of Contamination 18

3.0 Current and Potential Future Surface and Sub-Surface Routes of Human orEnvironmental Exposure 18

3.1 Likelihood for Migration 193.2 Current and Potential Future Land and Water Uses 193.2.1 Land Uses 193.2.2 Groundwater Use 19

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RECORD OF DECISIONBountiful/Woods CroWSth South PCE Pluma NPL Site - Operable Unit 1 September 2006

4.0 Summary of GUI Risks.......... 204.1 Summary of Human Health and Ecological Risk Assessment 204.2 Identification of Chemicals of Concern 214.3 Exposure Assessment - Hatchco Property 224.4 Exposure Assessment - Downgradient of the Hatchco Property 22

4.5 Human Pathways „ ..234.5.1 Direct Ingestion 234.5.2 Inhalation of VOCs Released to Indoor Air from Indoor Water Uses 234.5.3 Inhalation of VOCs Released from Groundwater to Air Via Soil Transport 23

4.6 Toxicity Assessment... 23

4.7 Risk Characterization 24

4.8 Results for Human Receptors 254.8.1 Risks from Ingestion of Groundwater 254.8.2 Risks from Inhalation of VOCs Intruding from Groundwater by Vapor Intrusion 264.8.3 Risks from Inhalation of VOCs Released During Indoor Use of Groundwater 264.8.4 Combined Risks from All Exposure Pathways 26

5.0 Uncertainties 275.1 Summary of Uncertainties 27

6.0 Remedial Action Objectives 286.1 Need for Remedial Action 286.2 Sub-Soil (Saturated Zone) Remedial Action Objective 286.3 Groundwater Remedial Action Objectives 296.4 Clean-up Goals 29

7.0 Description of Alternatives 297.1 Common Elements 297.2 Alternative 1 - No Action Alternative 307.3 Alternative 2 - Monitored Natural Attenuation (MNA) With Institutional Controls 317.4 Alternative 3 - Surface Capping with Institutional Controls , 317.5 Alternative 4 - Soil Vapor Extraction with Institutional Controls 317.6 Alternative 5 - Excavation with Offsite Disposal 317.7 Alternative 6 - Enhanced In-Situ Biological/Chemical Remediation with Institutional Controls 327.8 Alternative 7a - Treatment via Air Stripping With Institutional Controls 327.9 Alternative 7b - Treatment via Ultraviolet Oxidation With Institutional Controls 327.10 Alternative 7c - Discharge to Public Owned Treatment Works (POTW) With Institutional Controls 337.11 Summary 33

8.0 Comparative Analysis of Alternatives Criteria 338.1 Evaluation of the Proposed Alternative 348.1.1 Overall Protection of Human Health and the Environment 348.1.2 Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) 358.1.3 Long-term Effectiveness and Permanence 358.1.4 Reduction of Toxicity. Mobility, or Volume of Contaminants through Treatment 358.1.5 Short-term Effectiveness 368.1.6 Implementability 368.1.7 Cost 378.1.8 State Acceptance 378.1.9 Community Acceptance 37

9.0 Principal Threat Wastes.. 38

10.0 Selected Remedy 3810.1 Summary of the Rationale for the Selected Remedy for Groundwater Contamination 38

11.0 Description of the Selected Remedy - 39iii


11.1 Step 1 - Institutional Controls (ICs) 3911.2 Step 2 - Monitoring 4011.3 Step 3 - Well Abandonment 4011.4 Step 4 - Groundwater Treatment 4011.5 Step 5 - Exit Strategy 41

12.0 Summary of the Estimated Remedy Costs 41

13.0 Expected Outcomes of the Selected Remedy 4113.1 Available Land Use After site Cleanup •. 4113.2 Clean-up Levels 4113.3 Statutory Determinations 4213.4 Protection of Human Health and the Environment 4213.5 Compliance with Applicable or Relevant and Appropriate.Requirements 43.13.6 Cost Effectiveness 4413.7 Utilization of Permanent Solutions and Alternative Treatment (or Resource Recovery) Technologies

to the Maximum Extent Practicable (MEP) 4413.8 Preference for Treatment as a Principal Element 4413.9 Five Year Review Requirements 4514.0 Documentation of Significant Changes from Preferred Alternative of Proposed Plan 45PART 3: RESPONSIVENESS SUMMARY 46Appendix A - Public Comment Meeting Transcript 46Appendix B — Responses to Hatchco Comments 46

IV

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCE Plume NPL Site - Operable Unit 1 . September 2006

LIST OF FIGURES

1 Site Location Map2 Historic Aerial Photograph - April 10, 19853 Aerial Photograph - OU1, Industrial/residential Areas4 Conceptual Site Model for Exposure to Groundwater5 Operable Unitl - TCE Groundwater Plume5 A Isoconcentratior, Contour Map of Chlorinated Hydrocarbons5B Geological Cross-Section Traverse6 Historic Site Features Location Plan7 Historic Aerial Photograph - May 31, 19958 Schematic Diagram, Bountiful/Woods Cross 5th South, Davis County, Utah9 Geological Cross-Section at OU110 Sub-surface Soil Sampling Results11 TCE in Vadose Zone Soils, Sub Area 3 - 950 West, Davis County Utah12 Inferred Potential Source Area13 Cross Section - Upper, middle and Lower Zones

LIST OF TABLES

1 PCE and Degradation Compounds - April 20052 PCE and Degradation Compounds - May 20053 Groundwater Results Exceeding Primary MCLs4 VOCs Detected in Sub-surface Soils5 Evidence of Biodegradation of Chlorinated Organics6 Maximum PCE and Degradation Compounds Results in Domestic Wells7 Chemicals of Human Health Concern at Operable Unit 18 Summary of Statistics and Exposure Point Concentrations of Groundwater

Chemicals of Concern9 Exposure Parameters Used in the Risk Assessment For OU110 Cancer Toxicity Data11 Summary of Total Cancer Risk to Current/Future Residents and Workers From

Ingestion of Groundwater12 Summary of Cancer Risks to Current/Future Residents and Workers from

Inhalation of VOCs Related to Indoor Air from Groundwater by Vapor Intrusion13 Summary of Cancer Risks to Current/Future Residents and Workers from

Inhalation of VOCs Related to Indoor Air During Indoor use of Groundwater14 Summary of Total Cancer Risks to Current/Future Residents and Workers from

all Exposure Pathways15 Summary of Uncertainties16 Comparative Aaalysis Using NCP Criteria17 Chemical-Specific ARARs18 Action-Specific ARARs19 Estimated Cost for the Selected Remedy


ACRONYMS

A-3ARARATVBRABDLbgsBHHRACERCLAcis-DCECOCCOPCEPAERAESDFFSHEASTHIHDRHQICsIRISLOAELMCLMCLGMEPmg/kgMTBEOU1OU2NCPNPLO&MPAPAHPCEPOTWppbppmRAORBCRCRARI-HDRRI-CDMRI/FFS-HDRRLTFS-CDM

Area of InterestApplicable or Relevant and Appropriate RequirementsAlternate Toxicity ValueBaseline Risk Assessment - HDR Engineering Inc.Below the Laboratory Detection LimitBelow the Ground SurfaceBaseline Human Health and Ecological Risk Assessment - SRCComprehensive Environmental Response, Compensation, and Liability ActDichloroethene (Contaminant of Concern, Degradation Product of TCE)Chemical of ConcernChemicals of Potential ConcernUnited States Environmental Protection AgencyEcological Risk AssessmentExplanation of Significant DifferencesFocused Feasibility StudyHealth Effects Assessment Summary TablesHazard IndexHDR Engineering, Inc. (Contractor working for Hatchco)Hazard QuotientInstitutional ControlsIntegrated Risk Information SystemLowest Observed Adverse Effects LevelMaximum Contaminant LevelMaximum Contaminant Level GoalsMaximum Extent Practicablemilligrams per kilogram or parts per million (ppm)Methyl Tert-Buthyl EtherTCE Groundwater Plume, Hatchco Property, Area-3,PCE Groundwater PlumeNational Contingency PlanNational Priorities ListOperation and MaintenancePreliminary AssessmentPolycyclic Aromatic HydrocarbonsTetrachloroethene - Contaminant of ConcernPublic Owned Treatment Works - Municipal Water Treatment Plantparts per billionparts per millionRemedial Action ObjectivesEPA Region 3 Risk Based ConcentrationsResource Conservation and Recovery ActRemedial Investigation - HDR Egineering Inc.Remedial Investigation - CDMRemedial Investigation/Focused Feasibility Study - HDR Engineering Inc.Remedial Investigation/Focused Feasibility Study - CDM Engineering Inc.

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RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Plume NPL Site - Operable Unit 1 September 2006

ROD Record of DecisionRPM Remedial Project ManagerSARA Superfund Amendments and Reauthorization Act of 1986SI Site InspectionSite Bountiful/Woods Cross/5th South PCE Plume NPL Site, OU1 and OU2site OU1SQL Sample Quantification LimitSVOCs Semi-Volatile Organic CompoundsTCE Trichloroethene (Contaminant of Concern)TCLP Toxicity Characteristic Leaching ProcedureTEQ Toxicity Equivalence Quotientug/kg micrograms per kilogram (ppb)ug/L micrograms per Liter (ppb)US United StatesVC Vinyl Chloride (Contaminant of Concern - Degradation Product of TCE)VOCs Volatile Organic Compoundsyd3 cubic yards< less than> greater than

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THE DECLARATION

1.1 Site Name and Location

This Record of Decision (ROD) is for the Bountiful/Woods Cross/5th South PCE Plume NPLSite, Operable Unit 1, located between Interstate 15 and 800 West Street, and between 500 Southand 700 South streets in Woods Cross, Davis County, Utah (Figure 1). The EPA SiteIdentification Number is UT0001119296.

1.2 Statement of Basis and Purpose

This decision document presents the Selected Remedy for the Bountiful/Woods Cross/5th SouthPCE Plume, Operable Unit 1 (OU1), which was chosen in accordance with the ComprehensiveEnvironmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended bythe Superfund Amendments and Reauthorization Act of 1986 (SARA), and, to the extentpracticable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). Thisdecision is based on the Administrative Record for the Site.

The remedy was selected by EPA Region 8. The State of Utah Department of EnvironmentalQuality (UDEQ) concurs with the selected remedy.

1.3 Assessment of OU1

The response action selected in this ROD is necessary to protect the public health or welfare orthe environment from actual or threatened releases of hazardous substances and pollutants orcontaminants into the environment.

1.4 Description of Selected Remedy

The Bountiful/Woods Cross/5th South PCE Plume NPL Site has two operable units. OperableUnit 2 addresses a PCE groundwater plume emanating from the Bountiful Family CleanersFacility located at 244 South 500 West, Bountiful, Utah. The remedial investigation/feasibilitystudy and ROD for Operable Unit 2 is scheduled for completion during calendar year 2006.

The selected remedy for OU1 addresses both sub-soil and groundwater contaminated withTetrachloroethene (PCE), Trichloroethene (TCE), cis Dichloroethene (cis-DCE), Vinyl Chloride(VC) and other volatile organic compounds (VOCs). The selected remedy will remove thepotential threat to human health and it will achieve an accelerated risk reduction throughtreatment/destruction of contaminants in groundwater at OU1. The remedy also will meet thestatutory preference for the selection of a remedy that involves treatment as a principal element.The major components for the Selected Remedy include:

• Institutional controls (ICs) will be required to eliminate potential exposure to

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groundwater and ensure protectiveness of the remedy. At the source, the primary form ofICs will be proprietary controls, specifically, a restrictive covenant and easement whichwill require consultation with EPA/UDEQ prior to any earth disturbing activity (i.e.,excavation of soil). In addition, ICs will restrict well drilling in areas affected by theplume. ICs are described in detail hi Section 7.1 and Section 11.1:

• Injecting chemical/biological agents (food-grade compounds and microbes) into thecontaminated sub-surface soil, and the saturated zone to enhance the biodegradation ratesof the contaminants of concern;

• Monitoring groundwater to ensure the plume will respond to treatment over time. Newand selected existing monitoring wells will be used to track VOCs and natural attenuationparameters until the Maximum Contaminat Levels (MCLs) standards are achieved. Thefirst monitoring event will establish a baseline and will take place prior to the firstinjection of biological/chemical agents into the contaminated zone. Monitoring willcontinue until the Remedial Action Objectives (RAOs) are met or as required by the firstfive-year review.

• During each five-year review, EPA, in consultation with UDEQ, will review themonitoring data and evaluate the protectiveness of the remedy. Also, in consultation withUDEQ, EPA may modify the groundwater monitoring strategy as appropriate to ensurethat the data gathered support the clean-up objectives. Five-year reviews will be requireduntil the RAOs are met.

1.5 Statutory Determinations

The Selected Remedy is protective of human health and the environment, complies with Federaland State requirements that are applicable or relevant and appropriate to the remedial action, iscost effective, and utilizes permanent solutions and alternative treatment technologies to themaximum extent practicable.

This action also satisfies the statutory preference for treatment as a principal element of theremedy. The selected remedy reduces the toxicity, mobility and volume of hazardous substances,pollutants or contaminants through treatment at the source, and by enhancing the chemical andbiological degradation of the contaminants of concern in the groundwater plume.

Because this remedy may take more than five years to attain RAOs and clean-up levels, a policyreview will be conducted within five years of the initiation of the remedial action to ensure thatthe remedy is, or will be, protective of human health and the environment.

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCE Plume NPL Site - Operable Unit I September 2006

1.6 Data Certification Checklist

The following information is included in the Decision Summary section of this Record ofDecision. Additional information can be found in the Administrative Record file for this Site.

• Current and reasonably anticipated future land use assumptions and current and potentialfuture beneficial uses of groundwater used in the Baseline Risk Assessment and ROD(Section 2.4. H

• Baseline risk represented by the chemicals of concern (Section 4)• Chemicals of concern and their respective concentrations (Section 4.2)• How source materials constituting principal threats are addressed (Section 9)• Key factor(s) that led to selecting the remedy (i.e. describe how the Selected Remedy

provides the best balance of tradeoffs with respect to the balancing and modifyingcriteria, highlighting criteria key to the decision) (Section 10.1)

• Estimated capital, annual operation and maintenance (O&M), and total present worthcosts, discount rate, and the number of years over which the remedy cost estimates areprojected (Section 12.0)

• Potential land and groundwater use that will be available at the Site as a result of theSelected Remedy (Section 13.1)

• Clean-up levels established for chemicals of concern and the basis for these levels(Section 13.2)

1.7 Authorizing Signatures

This Record of Decision documents the selected remedial action to address the groundwatercontamination emanating from the Bountiful/Woods Cross/5th South PCE Plume NPL Site,Operable Unit 1 .

EPA Region 8 approves the selected remedy as described in this ROD.

Max H. Dodson DateAssistant Regional AdministratorOffice of Ecosystems Protection and RemediationU.S. Environmental Protection Agency, Region 8


The following authorized official at the State of Utah concurs with the selected remedy for theBountiful/Woods Cross/Sth South PCE Plume NPL Site, Operable Unit 1.

— ^fr- ,-

Dianne R. NielsonExecutive DirectorUtah Department of Environmental Quality

Date


THE DECISION SUMMARY

2.0 Site Name, Location, and Brief Description

The Bountiful/Woods Cross/5th South PCE Plume NPL Site, Operable Unit 1 (OU1), alsoknown as the Hatchco property, is located between Interstate 15 and 800 West Street, andbetween 500 South and 750 South streets in Woods Cross, Davis County, Utah. The Hatchcoproperty is located in Section 25, Township 2N, Range 1W of the Salt Lake Base Line andMeridian. The street address is 643 South, 800 West and the property's geographic coordinatesare 40°52'57" north latitude and 111°54'02" west longitude (Figure 1).

The Comprehensive Environmental Response, Compensation, and Liability Information System(CERCLIS) Identification Number is UT0001119296. The lead agency for OU1 is the U. S.Environmental Protection Agency (EPA). The Utah Department of Environmental Quality(UDEQ), Division of Environmental Response and Remediation (DERR) is the supportingagency. The Site was proposed for listing on the National Priorities List (NPL) in the FederalRegister on December 1, 2000, and was placed on the final NPL on September 13, 2001. TheSite cleanup is planned to be conducted using Superfund Trust funds.

W. S. Hatch Company initially operated on 13 acres, 10 of which are now owned by KalahariProperties (Kalahari). Properties adjacent to the Hatchco property include the Holly Refinery andMarketing Company to the north, and roadways to the east, west and south. The property terrainis basically flat. The topography of the area surrounding the Hatchco property slopes gently tothe west at approximately 0.025-feet per foot and lies at an elevation of 4,300-feet above meansea level.

2.1 OU1 History and Enforcement Activities

2.1.1 Site History and Land uses

W. S. Hatch Company (Hatchco) operated at the Site as a specialized carrier of bulk petroleum,petroleum products, petroleum solvents (such as toluene and xylene), and asphalt from 1936 to1986. Hatchco facilities were also used to service, clean, and park tractor-trailers and tanktrucks.

Hatch Service Company, a wholly owned subsidiary of Hatchco, also operated at this location.Hatch Service Company trucks reportedly carried ammonium nitrate, fuel oil, and high-energyfuel which were mixed by the truckload and used as explosives at mining operations. HatchService Company ceased operations in the late 1980s and was involuntarily dissolved onDecember 1,1998. At the peak of their operations, the facility was home to approximately 75trucks, 200 trailers, and 125 employees (Figure 2).

RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Plume NFL Site - Operable Unit 1 September 2006

Jack B. Kelley Inc., a Texas corporation, purchased all of Hatchco's stock on December 10,1986. The trucking operations continued until February 1996. In 1995, business operations werewinding down on the original 13 acres, and Hatchco began removing structures to prepare aportion of the property to be sold. Hatchco sold 10 acres to Kalahari on December 30,1997.Hatchco still retains title to approximately three of the original 13 acres.

The primary release mechanisms for contaminants at OU1 include leaks, spills, direct discharge,and infiltration to the surface or sub-surface. It is believed that the facility used various solventsto service, clean, and maintain the trailers and tank trucks. Media effected by the potentialreleases include surface soil, sub-surface soil, groundwater, and air. During the RemedialInvestigation no surface water impacts were identified within the OU1 groundwater plumeboundary.

2.1.2 Previous Investigations and Actions Taken At OU1

Several environmental investigations and actions occurred at OU1. In 1995, Hatchco hiredTRTech to perform a Phase I Environmental Survey on the original 13-acre Hatchco property. Inthe Phase I, TRTech identified several environmental issues, including chlorinated solventcontamination of the shallow aquifer.

In 1996, EPA's Superfund Technical Assessment and Response Team (START) took severalsamples in the area in an attempt to identify the extent of groundwater contamination. Results ofthe START report confirmed the presence of chlorinated solvents in groundwater at the Jack B.Kelley Hatchco property with concentrations as high as 980 parts per billion (ppb).

From 1995 to 1998 Hatchco removed structures associated with potential past releases ofcontaminants of concern (an underground waste oil storage tank, a French drain, and anunderground oil/water separator).

The waste from these operations was stored in a 200 gallon underground tank. In 1995, the tankwas removed. Before removal, material from the tank was pumped into 55 gallon drums fordisposal. The waste in the drums was characterized as containing waste petroleum products,carbon disulfide, methylene chloride, TCE, lead, and mercury. In 1996, the Utah Solid andHazardous Waste Control Board issued a "no further corrective action" letter.

During the French drain removal, the oil residue in the drain was tested and, although chlorinatedsolvents were present in the sample, the oil waste was reported to be nonhazardous. Accordingto the Hatchco Remedial Investigation Report, a contractor encountered gravel in the Frenchdrain at a depth of approximately 6-feet below the ground surface. The contaminated soils weretreated with water and nutrients as part of a natural attenuation plan.

Preliminary Assessment (PA) -1998. Through a Cooperative Agreement with EPA, the UDEQconducted a Preliminary Assessment (PA) of the Hatchco/Jack B. Kelley Trucking Property,EPA ID# UTD003807930. At the time the PA was conducted (1998) GUI covered 13 acres ofland as shown in Figure 2. The property is rectangular in shape with the long axis oriented westto east. The eastern half of the property was covered with natural grasses. The western half wascovered with asphalt and was occupied by buildings (welding shop, wash rack, and mechanical

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shop) where semi-trucks and trailers were repaired and maintained. Grease, oils and solvents,including chlorinated solvents, were used extensively in the mechanics shop during the operationof the facility.

The principal PA conclusions are that soils at the Hatchco property were contaminated and thatthe wash rack and adjacent area appeared to be the primary source of contamination for OU1.Groundwater in the shallow aquifer was contaminated with solvents and presented the primarypathway for contaminants to migrate to potential receptors. There are 45 public supply wellswhich serve 104,477 people and over 2,000 privately owned wells located within a 4-mile radiusfrom the Site. Additional information and conclusions are presented in the PA (1998). Theprimary contaminants of concern were chlorinated solvents. Other potential contaminants in thearea include: greases, oils, diesel fuel, waste fuel, and waste oil.

The oil/water separator was removed in 1998. Petroleum hydrocarbons were detected at a depthof about three feet under the surface. However, no chlorinated solvents were detected at thislocation.

In 1998, TRTech conducted a pilot test and operated a low-volume air sparging system to removevinyl chloride from the shallow aquifer. Reportedly, the pilot test was effective in reducing PCE,TCE and VC concentrations in groundwater; however, a report on the air sparging system resultsand groundwater impacts downgradient from the Hatchco property was not made available forEPA's review.

The Hatchco property is now vacant and fenced, all structures and contaminated surface soilshave been removed. Detailed information on previous investigations and actions taken at theOU1 can be found in the Remedial Investigation Final Report (2003).

2.1.3 Remedial Investigation/Feasibility Study, 2001-2006

EPA and Hatchco entered into an Administrative Order on Consent for (AOC) for a RemedialInvestigation/Feasibility Study (RI/FS) at Operable Unit 1, EPA Docket No. CERCLA-8-2001-14. Hatchco completed the RI/FS in July 2004. The purpose of the RI/FS was to determine thenature and extent of contamination caused by the release or threatened release of hazardoussubstances, pollutants or contaminants at or from the Hatchco property and to determine andevaluate alternatives to prevent, mitigate, or otherwise respond to, or remedy, any release orthreatened release from the property. The results from the Hatchco RI confirmed the presence ofhazardous substances, pollutants or contaminants in the Hatchco property sub-surface soil and ingroundwater.

Because it was believed that there was a potential secondary source, the Hatchco RI onlyinvestigated the nature and extent of the groundwater plume from the Hatchco property to thesuspected secondary source location area (in the vicinity of MW-14S) (Figure 5A). EPA took thelead to address the suspected secondary source via the Remedial Investigation/Feasibility Study(RI/FS) for Operable Unit 2 (OU2), study on Area of Interested Number 3 (A-3), illustrated onFigure 3. A potential secondary source was suspected in this area because the groundwaterconcentrations upgradient of A-3 were lower than the concentration at the location of thesuspected secondary source. Results from the A-3 investigation do not support the presence of a

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secondary source. In fact, subsequent sampling results collected via the OU2 RI, show asignificant TCE concentration decrease at A-3 (MW-14S) and a concentration increase at twowells (MW-02S and MW-02D) located downgradient of the suspected secondary source, (Figure5). At MW-14-S, TCE concentrations decreased from 551ug/L (July 2003) to 3.1ug/L (April2005), and 110 ug/L (May 2006). TCE concentrations in MW-02S range from 58 ug/L (2001),36 ug/L (April 2005), to 420 ug/L (May 2006). At MW-02D, TCE concentrations range from280 ug/L (2001), to 380 ug/L (April 2005), and 240 ug/L (May 2006). Although it was notdemonstrated by the remedial investigations for OU1 and OU2, it is conceivable that the plumecondition observed during the Hatchco RI, was due to the 1998 air sparging pilot test.Groundwater sample results from April 2005 and the May 2006 sampling events are provided inTables 1 and 2.

Also, results from the remedial investigation for OU2 identified twenty-six domestic wells and amunicipal water supply well located within a mile side-gradient of the OU1 groundwater plume.The closest domestic wells are located within 1,000 feet from the leading edge of the TCE plume(Figure 5). The results of the groundwater contamination are presented in Section 2.6 of thisROD.

In December 2004, the EPA decided to complete the RI/FS for OU2 prior to issuing the ROD forOU1. The decision was to allow for a broad assessment of the groundwater conditions at theSite. Also, in order not to stall the work at OU1, EPA decided to conduct a pilot test to collectdata to support the remedial design for the Proposed Cleanup Plan for OU1. In July 2005, EPAinitiated a Pilot Study Implementation Plan designed to collect data on natural attenuationparameters, to assess biodegradation rates, and to test the organic compounds selected toaccelerate the degradation of the contaminants of concern. EPA completed the RI/FS for OU2 inAugust 2006.

2.1.4 Ecological Risks

Ecological risks were determined to be below the level of concern. This conclusion was basedon an evaluation of the low potential for contaminated groundwater to discharge to surface water,the lack of suitable natural habitat in the area, and the industrial/commercial location of the Site(HDR Base Line Risk Assessment (BRA)). Aquatic impacts are deemed unlikely due to thedistance between the Site and the Great Salt Lake (approx. 2.5 miles) and the fact that no surfacewater features were identified within the OU1 groundwater plume boundary.

2.1.5 Enforcement Activities

In July of 1997, EPA completed an initial/preliminary Potentially Responsible Party Search forthe Site, which was augmented by the issuance of information request letters to W.S. HatchCompany in January of 2001 and February of 2003. Other parties of interest for OU1 were sentinformation request letters in January of 2001 and in June of 2002.

On September 28, 2001, Hatchco entered into an Administrative Order on Consent for theRemedial Investigation/Feasibility Study for OU1.


In April of 2004, EPA issued a General Notice of Potential Liability and Intent to Perfect aSuperfund Lien letter to W.S. Hatch Company. On July 7, 2004, the Lien was recorded with theDavis County Clerk and Recorder's Office.

Negotiations for future work at OU1 ensued. Hatchco claimed a limited ability to pay andsubmitted financial information to substantiate their claim. On December 9, 2005, W.S. HatchCompany, Inc. and its parent corporation Jack B. Kelley, Inc. entered into an AdministrativeSettlement Agreement and Order on Consent settling their liability for all response costs incurredand paid, or to be incurred and paid, in connection with the work conducted at OUlin exchangefor a $490,000 settlement ($450,000 from Hatchco and $40,000 from Jack B. Kelley).

2.2 Community Participation

Community involvement efforts for OU1 included issuance of fact sheets, holding publicmeetings, publishing public notices and press releases, and developing a community involvementplan. An information repository was established at the Davis County Library, South Branch,enabling the public to view documents used in making decisions about this Site. A summary ofthese activities is included in this section.

In December 2000, a public notice was published announcing EPA's decision to propose thelisting of the Bountiful/Woods Cross Site on the National Priorities List. In March 2001, a factsheet was issued to inform the public of a domestic well sampling program for residentialproperties that might be impacted by the Site's contaminants. A news release announcing thefinal listing of the Site was published in local papers in September, 2001.

In the summer of 2002, EPA conducted community interviews to provide an assessment of thecommunity concerns. Included in the interviews were elected officials, city engineers, publicworks directors, and community members that may be impacted by the Site's contaminants. Theresults of the interviews are presented in the August 2002, Community Involvement Plan.

In September 2002, a public health assessment, conducted by the U.S. Department of Health andHuman Services - Public Health Service Agency for Toxic Substances and Disease Registry, wasmade available for public review and comment. Also that month, the public received a ProjectUpdate Fact Sheet. The Utah Department of Health, Davis County Health Department, UtahDepartment of Environmental Quality, and the Environmental Protection Agency produced abrochure about the chemicals in the groundwater and what it meant to the public.

In April 2004, a meeting with Bountiful City officials and Davis County officials was held todiscuss the need to do additional water sampling. A Fact Sheet announcing the plans for moresampling was mailed to local residents.

An Administrative Record was placed in the Davis County Library, South Branch on August 5,2004, as well as the EPA Region 8 Superfund Record Center, and at the Utah Department ofEnvironmental Quality - Division of Environmental Response and Remediation. The notice ofthe availability of the Administrative Record and an announcement of the Proposed Plan public

RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Plume IS PL Site - Operable Unit 1 September 2006

meeting was published in the Davis County Clipper and the Deseret News on August 7, 2004.

The Proposed Plan Fact Sheet was issued to the public on August 5, 2004. The Utah Departmentof Environmental Quality and the Environmental Protection Agency accepted comments on theplan from August 7, 2004 to September 7, 2004. On August 24, 2004, a public meeting was heldto discuss the various alternatives and to review in more depth the preferred alternative. OnAugust 23, EPA received a request from Hatchco to extend the comment period to October 7,2004. A response to the comments received during this period is included in the ResponsivenessSummary located in Appendix B of this ROD. In July of 2005, EPA issued a fact sheet toannounce to the public the initiation of a pilot study to support the remedial design for OU1.

2.3 Scope and Role of Operable Unit or Response Action

Due to the complexity of the groundwater contamination, the Bountiful/Woods Cross/5 th SouthPCE Plume NPL Site was divided into two operable units. This ROD addresses Operable Unit 1(OU1) and identifies the selected remedy to clean up the groundwater contaminated with TCEand the degradation products emanating from the Hatchco property. The remedy documented inthis ROD includes remedial action necessary to protect human health and the environment.

The remedial investigations concluded that the groundwater in the shallow aquifer iscontaminated with VOCs above the Maximum Contaminant Levels (MCLs). The riskassessments concluded that the groundwater should not be used as a drinking water supply or forindoor domestic use. The Hatchco risk assessment determined that the sub-surface at theHatchco property is contaminated, but does not pose a direct exposure concern to human health.However, the sub-surface poses a continued source of contamination to groundwater. Theselected remedy utilizes In Situ Chemical/Biological Remediation processes to accelerate thedegradation of the contaminants of concern in groundwater and will accelerate the reduction ofrisks to human health and the environment.

The remedy also requires an Environmental Notice and Institutional Controls (May 17, 2006) onthe Hatchco property deed describing the nature and extent of the sub-surface and groundwatercontamination at OU1. Institutional controls will also be established to prohibit the installationof new domestic wells within the projected perimeter of the plume and will set controls toprevent the indoor use of groundwater from existing wells.

Operable Unit 2 (OU2) is addressed under the RI/FS for OU2. The OU2 ROD will address PCEcontamination emanating from the vicinity of the Bountiful Family Cleaners property locatedeast and upgradient of the Holly Refining & Marketing Company. The RI/FS for OU2 wascompleted in August 2006. The Bountiful Cleaners, Inc., owners of the Bountiful FamilyCleaners property, entered into an AOC to perform a limited Remedial Investigation for theirproperty only, at Operable Unit 2, EPA Docket No. CERCLA-8-2003-002. It is anticipated thatthe remedy for OU2 will be conducted using Superfund Trust funds.

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2.4 Summary of OU1 Characteristics

2.4.1 Conceptual OU1 Model

As discussed in Section 2.2.1, the Hatchco property was used to repair, clean, and maintaintractor trailers and tank trucks. This land utilization presented the conditions for spills, leaksand/or direct discharges of petroleum hydrocarbons, solvents (such as benzene, toluene) andchlorinated solvents to the surface soil. Infiltration of these solvents into the soil resulted inelevated levels of contamination. All the contaminated surface soil has been removed. Currentlythe remaining contaminated sub-surface and the contaminated shallow groundwater on theHatchco property are the primary sources of contamination. Other than presenting a continuoussource of groundwater contamination, the contaminated sub-surface, 15 to 20 feet below theground surface (bgs), does not present a direct human health exposure concern.

Based on the current and likely future land uses in the area of the PCE/TCE plume, the humanpopulations most likely to be exposed include current and future residents, and current and futureworkers in area businesses. Potential exposure pathways by which residents and workers mightbe exposed to VOCs in groundwater include the following:

• Direct ingestion of the water (from a well) as drinking water• Dermal contact with the water while showering or bathing• Inhalation of volatile organic chemicals (VOCs) that are released from indoor water uses

to indoor air• Inhalation of VOCs that are released from groundwater and migrate through soil into

indoor air• Inhalation of VOCs that are released from groundwater and migrate through soil into

outdoor air• Incidental ingestion of groundwater that occurs at the surface

However, not all of these potential exposure routes to groundwater are likely to be of equalconcern. Exposure scenarios that are considered most likely to be of concern are shown in theSite Conceptual Model by boxes containing a solid circle (Figure 4). Greatest attention isfocused on quantification of exposure from these pathways in order to determine if the pathwayscontribute significant risk. Pathways that are judged to contribute only minor exposures areshown by boxes with an open circle. Section 3.2 of the Baseline Human Health and EcologicalRisk Assessment (BHHRA) presents a detailed description of these pathways, and an analysis oftheir relative importance for human exposure. These scenarios were considered based on theexpected current and future land use.

Although no domestic groundwater use is known within the perimeter of the delineatedgroundwater plume at OU1, contaminated groundwater is flowing to the north-west whereseveral domestic groundwater wells are located. Some of these domestic wells are downgradientand within 1,000 feet from the leading edge of the plume (Figure 5).

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RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Flume NPL Site - Operable Unit 1 September 2006

2.4.2 Overview of OU1

Operable Unit 1, which includes the Hatchco property plus the extent of the TCE groundwaterplume, is located in Woods Cross, Davis County, Utah. OU1 is delineated by the extent of thegroundwater plume and consists of approximately 42 acres of land. The contaminated plumeextends approximately 3,000 feet downgradient from the Hatchco property. The source of thegroundwater contamination is within the perimeter of the three-acre Hatchco property.Currently, the three acre lot is vacant and fenced, and all structures and the contaminated surfacesoil have been removed.

The highest TCE concentrations were detected in the sub-surface, 15 to 25 feet below the groundsurface (bgs), beneath the wash rack formerly located approximately in the center of the property(Figures 6 and 7). A groundwater plume contaminated with TCE and degradation products startsat this location and extends to the west-northwest (Figure 5).

2.4.3 Geology

Operable Unit 1 is located west of the Wasatch Mountains and east of the Great Salt Lake in anarea known as the Wasatch Front (Figure 8). The Hatchco property is mainly flat and is locatedin the Basin and Range province on the southern portion of the East Shore Aquifer. The Basinfill deposits are characterized by unconsolidated and semi-consolidated sediments eroded fromthe mountains. The sediments tend to be thicker and coarser at the base of the mountains andbecome niter-bedded with gravel, sand, silts, and clay towards the Great Salt Lake.

Much of the north and east portions of OU1 are covered with gravel. Surface soils in non-driving areas consist of dark brown to black sandy, gravelly clay. All surface soils at samplinglocations were fill material. Native soils begin approximately 4 to 8 feet bgs at most sub-surfacesampling locations. Native sub-surface soils are primarily medium-stiff to stiff, medium tohighly plastic clays to approximately 17 feet bgs. Below the clays are layers of dense, well-graded sand and gravel, which alternate with layers of sandy, silty clay. Water is typicallyencountered in sand and gravel zones at 24 to 30 feet bgs. A clay aquiclude exists at the Hatchcoproperty at approximately 36 feet bgs. This low-permeability layer extends to 55 feet bgs in theboring used to install deep monitoring well MW-3D, below which there are clays alternating withminor (1 to 3 foot) layers of sand to 80 feet bgs. Below the clay at 80 feet bgs is sand and gravel.This sand and gravel extends to 91 feet bgs (MW-3D boring) and terminates at a clay base(Figures 5B and 9).

In borings outside the Hatchco property boundary line, approximately ten feet of native clay liesbelow fill and extends to 14 feet bgs. The vertical extent of the sand and gravel is not well knownat OU1 because downgradient borings were completed only a few feet below the depth wherewater was encountered. However, boring MW-12S was advanced three feet into dry-to-moistclay beginning at 24 feet bgs. As shown in Figure 9, this clay could be interpreted to be locatedin the same aquiclude encountered in the Hatchco property borings.

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2.4.4 Hydrogeology

East Shore AquiferGroundwater in the area is characterized by the East Shore Aquifer. The aquifer has beensubdivided into the shallow, intermediate and the deep artesian aquifers. Wells believed to becompleted within the shallow aquifer have completion depths between 60 to 250 feet bgs. Theintermediate aquifer is generally about 250 to 500 feet bgs, and the deep aquifer has depthsgreater than 500 feet bgs. The shallow, intermediate, and deep portions of the East Shore aquifermay also be hydraulically connected with one another (CDM 2002). Aquifer recharge isgenerally interpreted to be at the base of the Wasatch Mountains where the coarser deposits arepresent and runoff infiltration occurs. Groundwater flow is generally from the east-southeasttowards the west, following the topography towards the Great Salt Lake.

In the vicinity of OU1, two saturated intervals are considered relevant. At the Hatchco property,a shallow unconfined interval is present at depths ranging from about 24 to 30 feet bgs, with adeeper confined interval being present at approximately 80 feet bgs. A clay layer separates theshallow and deep intervals. The shallow interval is approximately 10 feet thick, and is present inthe unconsolidated, coarse-grained alluvial sediments noted in borings completed at OU1. Theconfined interval, investigated at the borings for deep monitoring wells MW-1D and MW-3D,lies below the clay that was first encountered at approximately 36-feet bgs. The vertical extent ofthis clay is approximately 44 feet (with occurrences of minor, 1 to 3 foot thick layers of silt andsand), extending to a depth of 80 feet bgs. The deep interval begins at 80 feet bgs and continuesto an undetermined depth, although clay was encountered at 91 feet bgs in both deep borings.Downgradient of the Hatchco property, groundwater is encountered at shallower depths(unconfined aquifer) due to ground elevations dropping to the west. Groundwater can be seen atdepths as shallow as 6.5 feet bgs (MW-14S). Monitoring wells were installed in the unconfinedaquifer just below depths where saturated conditions were first encountered. For this reason, thedeepest well, installed outside the Hatchco property, extends to 30 feet bgs (MW-1 IS).

Historically, the shallow aquifer in the area is mainly use for industrial and irrigation purposes.However, the shallow aquifer is classified by the State of Utah as a Class n drinking water source(drinking water quality groundwater) and some domestic wells are believed to be installed in thisaquifer.

2.4.5 Sampling Strategy

During the remedial investigations the following media were sampled: surface soil, sub-surfacesoil, and groundwater. There are no surface water features within the area impacted by OU1.

Over two hundred locations were sampled via a soil gas survey designed to locate and delineatepotential hot-spots. Thirteen surface soil samples (2 to 6 inches bgs) and fifteen sub-surfacesamples (7 to 35 feet bgs) were collected and confirmed the sub-surface contamination in thearea delineated by the soil gas survey. The soil gas samples were analyzed for VOCs and BTEXcompounds which include: Benzene, Toluene, Ethylbenzene and Xylene. The maximum TCEconcentration detected in sub-surface soil at OU1 was 90,956 ug/kg.

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Six geoprobe samples and a total of thirteen groundwater monitoring wells were installed toassess water quality conditions, to evaluate hydraulic gradients, and to define the nature andextent of groundwater contamination (Figure 5 A). Within the Hatchco property, the locations ofthe geoprobes and the monitoring wells were selected based on the soil gas survey, and the sub-surface sample results. The maximum TCE groundwater concentration detected on the Hatchcoproperty was 1348 ug/L (Geoprobe Sample 207) at a depth of 36 feet. The maximum TCEgroundwater concentration detected in the Hatchco property wells was 207 ug/L (MS-3S, screen23 to 33 feet bgs). The maximum TCE concentration detected in wells outside the propertyboundary was 507 ug/L (MS-14, screen 12 to 22 feet bgs). For comparison the MCLconcentration for TCE is 5 ug/L.

In addition, 19 groundwater samples were collected during the remedial investigation report forOU2 to assess the groundwater quality in Area 3. Contaminants of concern whoseconcentrations exceed MCLs are listed in Table 3.

2.4.6 Known and/or Suspected Sources of Contamination

The remedial investigations confirmed TCE contamination in the sub-surface and groundwater atOU1. Suspected sources of contamination include solvents utilized to clean and maintain tractortrailers and tank trucks. The Hatchco RI data show elevated concentrations of VOCs in the sub-surface located under the former wash rack and along the French drain. The data from the RIsupport that the bulk of the waste stream infiltrated into the ground surface from the drain systemservicing the facility - mainly the wash rack, the French drain, and the oil-water separator.

2.5 Types of Contamination and Affected Media

2.5.1 Surface Soil

There are no contaminants of concern in surface soils. Surface soil data reveal VOCs at levelsnear or below the detection limits. This is not unexpected considering the volatility of thecontaminants of concern and the fact that the Hatchco property has been vacant and inactive forseveral years. Also, prior to the RI, between 1995 and 1998, hot spots of contaminated surfacesoils were excavated, treated on the property and removed.

2.5.2 Sub-surface Soil

The waste materials considered for remedial action at OU1 include the saturated zone, at theHatchco property, which contains concentrations of COCs posing a potential source forgroundwater contamination. Contaminated sub-soils do not pose a health risk above a level ofconcern either through direct contact or through the inhalation of COC vapors collected in ahypothetical future OU1 structure.

In the absence of specific leaching tests on unsaturated zone soils, at OU1, soil screeningguidance (Technical Background Document, EPA, 1996a) was used to conservatively identifythe TCE concentration in soils that may constitute a source for groundwater contamination. The

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default threshold concentration for TCE is 60 ug/kg (based on a 20-fold dilution/attenuationfactor). This default value is driven by the potential of TCE in soils to act as a source forgroundwater contamination. Concentrations of TCE alone, in sub-surface soils range from 2,834ug/kg (Boring 64), 22,292 ug/kg (Boring 207) to 90,956 ug/kg (Boring 82), (Figure 10).

Using this default value (60 ug/kg) and the measured TCE concentration in the sub-soils at theHatchco property, a soil waste volume of 21,350 cubic feet was estimated. Calculationssupporting this estimate are found in Appendix K of the Hatchco RI Report. Averageconcentration for the sub-soil mass is estimated at 29,000 ug/kg. Additional concentrations ofcontaminants detected in sub-soil samples are listed in Table 4.

A review of the soil logs illustrates that, in general, the thickness of the contaminated zoneranges from 2 to 3 feet; however, this range is based on field observations, and it may vary byseveral feet.

2.5.3 Suspected Secondary Source

EPA conducted a separate investigation (CDM RI Phase 2, Remedial investigation for OU-2,Area 3) on sub-surface soil on a suspected secondary source. The location of this source wasbelieved to be in the vicinity of Jensen Automotive, an auto body shop located at 500 South and950 West, and slightly south of monitoring well MW-14S. EPA collected 25 soil samples in thevadose zone (portion of earth located above the groundwater table). The samples were collectedaround the Jensen Automobile building using six north-to-south transects at approximately 50feet intervals. The sample results show a single detect on the northwest side of the auto shop, ata TCE concentration of 0.09 ug/kg, (Figure 11). A provable location of a secondary source maybe directly under the building; however, there is no evidence of drains, sumps or cracks in thefloor inside the building. After considering the presence of only one positive low concentration(TCE) sample result with 24 non-detects and the absence of a physical pathway to the sub-building soils, EPA opted to spend the resources to clean up the groundwater.

2.6 Groundwater

2.6.1 Permanent Monitoring Wells

During the RI, groundwater samples were obtained from temporary wells, permanent monitoringwells, and domestic wells. The domestic wells were sampled as part of the remedialinvestigation for OU2.

A total of thirteen (11 shallow and 2 deep) monitoring wells were installed to evaluate thegroundwater contamination at OU1 (Figures 5A and 5B). Monitoring wells MW-1S and MW-1D were installed approximately 150 feet southeast of the 3-acre Hatchco property to establishbackground water quality conditions. Monitoring wells MW-2S, MW-3S, MW3D and MW-4Swere installed within the 3-acre Hatchco property, and seven wells were located downgradientand sidegradient of the property. The well locations were selected based on soil gas surveyresults and direct-push soil boring sampling activities discussed in Section 6.3.2 and 6.3.3 of the

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2003 RI report. All monitoring wells were developed and sampled for VOCs for four calendarquarters. With the exception of MW-1D and MW 3D, the groundwater samples were collectedclose to the water table surface. The sample results for the contaminants of concern exceedingMCLs are presented in Section 4.2.

Monitoring wells MW-2S, MW-3S and MW-10S were selected to assess the natural degradationindicators for the contaminants of concern (natural attenuation) at OU1. These monitoring wellswere chosen based on their location relative to the axis of the contaminant plume, and becausethese wells have shown the highest concentrations of chlorinated organics. Results of the naturalattenuation parameters are presented in Table 5, and presented in Section 7.4.3 of the Hatchco RIreport.

2.6.2 Domestic Wells

The UDEQ, in cooperation with EPA Region 8, collected groundwater samples from 26domestic wells. Although some of these wells are screened at deeper zones of the aquifer,geographically they are located within 1,500 feet downgradient from the leading edge of the TCEplume. Of the 26 domestic wells analyzed for VOCs, 20 wells show detects of PCE and TCE.Results of the contamination of domestic wells (designated as DW) are presented on Tables 6.

Of these results, six exceed the Utah standard for Maximum Contaminant Level or the FederalSafe Drinking Water Act Maximum Contaminant Level (MCLs) for PCE. It should be notedthat, although TCE has been detected in some domestic wells, none of these wells exceed theMCL value for TCE, which is the main contaminant of concern attributed to OU1. Furthermore,the data collected during the remedial investigations did not show a direct link between the TCEplume emanating from the Hatchco property and the TCE concentrations detected in thedomestic wells.

2.6.3 Municipal well - West Bountiful 5th South Well

An existing municipal production well is located approximately 2,600 feet from the Hatchcoproperty. The well belongs to the Weber Basin Water Conservation District and is located in theintersection of West 500 South Street and 1100 West Street. The District briefly operated thiswell in 2003, but ceased operations after receiving complaints from local residents that theirdomestic wells had lost significant water pressure. Currently, the District is not using the well,but in the future it intends to operate the well to meet irrigation demands. None of the sampleresults reported by the City detected contaminants of concern.

2.6.4 Groundwater Contamination

The groundwater flow direction follows the Site's topography, flowing from the higher areacontours at the eastern edge of the Hatchco property toward the north-west direction to the GreatSalt Lake. The Warm Springs Fault is located approximately at the same location as the leadingedge of the TCE groundwater plume. Several artesian domestic wells (DW) and a municipalwell (West Bountiful 5th South Well) are located near the western edge of the TCE plume(Figures 5 and 8). Although the City has not reported detection of contaminants of concern in the

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municipal well, some detections of PCE and TCE have been reported in the sample results fromdomestic wells (DW-17, DW-18, DW-19, DW-20, DW-21, DW-25) (see Table 6). It is worthnoting that these wells operate under artesian conditions. The well screens are set on the middleand the lower aquifers and the fate and transport of the contaminants of concern from the OU1source to the domestic wells has not been fully defined. However, results from the remedialinvestigation from OU2 support that the Warm Springs Fault may allow contamination tomigrate downward in the aquifer.

The vertical gradient between the unconfmed (shallow) and the confined (lower) aquifer wasobtained through two well clusters. One well cluster (MW-1S and MW-1D) is locatedupgradient of the Hatchco property; the second cluster (MW-3S and MW-3D) is located on theHatchco property. The vertical gradient was determined by measuring the difference between thehydraulic head of the two wells and dividing by the vertical distance from the bottom of theshallow well screen to the top of the deep screen. The results showed, at the Hatchco property, adownward gradient of 0.13 ft/ft and 0.12 ft/ft (Hatchco RI, Table 6-2) for the first and the secondclusters, respectively. The potentiometric surface of the shallow aquifer indicates the dominantgroundwater flow is to the west-northwest. However, a southerly flow component is inferred toexist south of the Hatchco property. This southerly flow component was not resolved during theRI; however, a corrective action investigation at the Holly Refinery (Request for CorrectiveAction Plan - Holly Refinery and Light Oil Dock, February 8, 2006) discovered an apparentgroundwater mound beneath the Light Oil Dock (LOD) facility. Pressure testing was conductedto determine if any of the lines in the area were leaking. The testing revealed a leak in the sewerline in the middle bay of the loading terminal which is the possible source of the observedgroundwater mound. The LOD facility is located approximately 300 feet north of the center ofthe Hatchco property. This leak may have been the cause for the southerly flow componentobserved during the OU1 RI. It is likely that groundwater level measurements collected duringthe RD/RA would confirm this hypothesis.

The magnitude of the horizontal groundwater gradient to the west-northwest across the shallowmonitoring well network has been calculated to average 0.003 ft/ft over the four quarters of data.The magnitude of the horizontal gradient is greater (0.005 ft/ft) to the west of MW-10S. East of

MW-10S the gradient is lower, at 0.001 ft/ft. An average hydraulic gradient of 0.005 ft/ft isestimated for the southerly flow component.

Three wells (MW-2S, MW-3S, and MW-12S) were selected to estimate the hydraulicconductivity of the shallow aquifer. The calculated values results show a hydraulic conductivityof 1.4 ft/day (MW-2S), 67.9 ft/day (MW-3S), and 2.7 ft/day (MW-12S), with a geometric meanhydraulic conductivity of 6.3 ft/day. These wells are screened in silty sand, clean sand, and silty-to-clean sand respectively. It should be noted that although a hydraulic conductivity of 6.3 ft/daywas used for the groundwater model; the hydraulic conductivity at OU1 is variable based on thesoil composition and on the results calculated for the three monitoring wells.

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RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Plume NFL Site - Operable Unit 1 September 2006

2.7 Location of Contamination and Migrate

2.7.1 Lateral and Vertical Extent of Contamination

Surface soils are not contaminated above a level of concern; therefore, surface soils do not pose athreat to human health and the environment. Contaminated surface soils were excavated, treatedand removed from the Hatchco property.

Sub-surface soils are contaminated and they pose a potential continuous source to groundwatercontamination. The estimated volume of contaminated soils with the potential to be acontinuous source of TCE contamination is estimated at 21,325 cubic feet. This sub-soilcontamination is at a depth that ranges from 9 to 20 feet (DPS-207 and DPS-082, respectively).The thickness of the contaminated sub-soils layer ranges from 2 to 3 feet. Field observationsindicate that in some cases this layer may vary by several feet. The inferred area of sub-surfacesoil contamination is presented in Figure 12.

Groundwater at OU1 is contaminated with PCE, TCE, DCE, and VC at concentrations thatexceed State and Federal drinking water standards. The groundwater depths within the perimeterof the TCE plume ranges from 12 to 49 feet below the ground surface and the plume extendsapproximately 3,000 feet downgradient from the Hatchco property. The domestic wells whereTCE has been detected are located on the Upper (0 to 59 feet bgs), Middle (60 to 160 feet bgs),and the Lower (greater than 160 feet bgs) portions of the aquifer (Figure 13). As notedpreviously, the data collected during the RIs did not show a direct link between the TCE plumeemanating from the Hatchco property and the TCE concentration detected in the domestic wells.

3.0 Current and Potential Future Surface and Sob-Surface Routes ofHuman or Environmental Exposure

The land at OU1 is utilized for industrial, commercial, agricultural and residential purposes. TheHatchco property is currently vacant and fenced. Properties adjacent to the Hatchco propertyinclude the Holly Refinery and Marketing Company to the north, a vacant lot to the east(Kalahari property), and roadways to south and west.

The HDR Baseline Risk Assessment (BRA) evaluated cancer and non-cancer risks for aconstruction worker in a trench, an indoor worker, working within the Hatchco propertyboundary, and the current and hypothetical future resident living on and in the near proximity ofthe Hatchco property boundary. Exposure scenarios considered direct contact/ingestion ofcontaminated soils for the trench worker as well as inhalation risk due to intrusion of organicvapors in the trench and indoor spaces. The BRA determined that risks were below a level ofconcern (cancer risk range 1E-04 and Hazard Index <1) for all scenarios, for the potentialexposure to contaminated soils. An assessment of potential ecological risks was limited to adiscussion of the current conditions at OU1 and a reconnaissance to assess potential forcontaminated groundwater to discharge to surface water. No groundwater discharge points wereobserved within the area impacted by the groundwater plume at OU1. As a result, ecological

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risks are considered to be below a level of concern.

The sub-surface soil at the Hatchco property is contaminated and it presents a potential source forcontaminants to leach to groundwater. High precipitation events could cause contaminated sub-soils to continue to release contaminants to groundwater.

3.1 Likelihood for Migration

The likelihood for migration of the contaminants of concern is high. The groundwater at OU1 iscontaminated and it will continue to migrate outside the Hatchco property boundary. Heavy rainsand fluctuating groundwater levels could cause contaminants of concern to continue to leachfrom the sub-soils into groundwater and flow towards a residential area where several domesticwells are located.

3.2 Current and Potential Future Land and Water Uses

3.2.1 Land Uses

The Hatchco property is currently vacant, fenced, and is zoned for commercial use. The futureuse of the Hatchco property remains uncertain although it is anticipated that it will be consistentwith its current use. Other land uses of the area impacted by the contaminated groundwaterplume at OU1 include: commercial, industrial, agricultural, and residential.

3.2.2 Groundwater Use

There are several domestic wells and one municipal well within a 1,500 foot radius from theleading edge of the TCE groundwater plume. One of these wells in the West Bountiful area iscompleted in the shallow (upper-unconfined, 0 to 59 feet bgs) aquifer. The remainder of thewells are completed in the middle (confined aquifer, approximately 60 to 160 feet bgs) or thelower aquifer (> 160 feet bgs). Although it is believed that these wells are currently used only forirrigation, in the past, some wells have been used for drinking water, and it is considered possiblethese wells could also be used for drinking or in the future for other indoor water use. Althoughcontaminants of concern have been detected in several domestic wells, the source of thiscontamination, as of the date of this ROD, has not been linked to the Hatchco property.However, about 300 feet west of MW-2S and MW-2D is the Warm Springs Fault. Results fromthe CDM RJ/FS for OU2 show the fault may allow the contaminant mass from OU2 to betransported vertically and downgradient of the fault into the deeper aquifer zone. The sametransport mechanism may be responsible for delivering contaminants of concern from OU1 intothe lower aquifer zones (Figures 5 and 13).

The Weber Basing Conservation District operates a municipal well (West Bountiful 5th, SouthWell). The well is located within 500 feet of the leading edge of the plume and approximately2,600 feet west of the Hatchco property. The well intake screen is placed between 325 to 600feet bgs. The District plans to use this well for irrigation as the demand increases withpopulation growth.

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4.0 Summary of OU1 Risks

4.1 Summary of Human Health and Ecological Rislk Assessment

The Baseline Human Health Risk Assessment (BHHRA) estimates the potential risk to humansand ecological receptors from contaminants of concern related to OU1, assuming that no action istaken to cleanup the contamination. The risk assessment identifies the contaminants andexposure pathways that need to be addressed by the remedial action.

For human receptors, EPA's decision to take action is based primarily on the presence ofcontamination in groundwater at levels that exceed drinking water standards. Because theconcentration of contaminants in groundwater tends to decrease as a function of distance fromthe source, and because most humans who use groundwater draw their water from a single well,human exposure was evaluated on a well-by-well basis. Current residents, living near OU1 maybe impacted in the future by contaminants migrating downgradient from the Hatchco property.Because it is believed that most workers or residents do not drink water from the shallow aquifer,the exposure pathway to groundwater ingestion is considered mainly hypothetical, although someexceptions may occur.

In October 2005, EPA and UDEQ conducted interviews to assess if any property owners withdomestic wells located downgradient from the Hatchco property were drinking contaminatedgroundwater. Results from the interviews indicate that there are up to seven residences wherethe well water is used for drinking; however, in all cases, the contamination levels are below theMCL. None of the well owners interviewed were interested in being connected to municipalwater wells as long as the contaminant levels remained below screening levels. Two other wellsare contaminated at levels above the MCL; however, the wells are used for stock watering only:

For ecological receptors, exposure can only occur if the groundwater is discharged at the surface(e.g., into a streams, lakes, or wetlands). Although there are no locations where contaminatedgroundwater from OU1 is known to discharge to the surface, screening-level risks werecalculated for aquatic receptors as if water from wells completed in the upper aquifer might reachthe surface (SRC, July 2004).

It is important to note that these risk estimates are screening-level and are based on veryconservative assumptions. In particular, it is assumed the concentration of VOCs in surfacewater is the same as the highest value in groundwater. However, if groundwater were rechargingto surface water bodies at or near OU1, it is likely that processes such as volatilization,degradation, and dilution would act to reduce the concentration in surface water to much lowerlevels than in the groundwater; consequently, the resulting risks to aquatic receptors would likelybe lower. This is consistent with the limited surface water data that are available, where VOCswere not detected in grab samples collected from two canals at the western edge of the Site.

A reconnaissance, in the vicinity of OU1, was conducted to identify any locations wheregroundwater discharges to surface water. The survey revealed no surface water downgradient ofOU1 or within the TCE plume (no streams or wetlands were noted between the Hatchco propertyand 1100 West Street). Mill Creek is a perennial stream located east of OU1 and flows to the

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north. The probability of impacts to Mill Creek from the contaminants emanating from OU1 isconsidered to be very low for the following reasons:

1) Mill Creek is located hydraulically upgradient from OU1.2) The depth to groundwater exceeds 20-feet.3) The creek is concrete lined in the vicinity of OU1.

Also, it is important to note that no ecologically sensitive scenarios were identified due to thelack of suitable habitat, and the industrial/commercial/residential settings around OU1. Giventhe distance from OU1 to the Great Salt Lake (approx. 2.5 miles) and the fact that no surfacewater features were identified within the TCE plume boundaries, the baseline risk assessmentsconcluded that OU1 poses no adverse ecological impacts. Consequently, ecological risks willnot be presented in subsequent sections of this ROD. Additional information on the ecologicalexposure pathways and exposure point concentrations are provided in the BHHRA (SRC 2005).

4.2 Identification of Chemicals of Concern

The BHHRA evaluated soil, sub-surface soil and groundwater. Surface water was not evaluatedbecause it is not present within the area impacted by OU1. Only the sub-surface soil andgroundwater media were found to have Chemicals of Concern (COCs). The chemicals ofpotential concern for OU1 evaluated quantitatively in the BHHRA risk assessments are presentedin Table 7.

Risks at OU1 are primarily due to TCE and/or VC, with the exception of two locations in theproximity of OU1. At location MW-3S/MW-3D, the risks are primarily due to PCE; at locationMW03U the risks are due mainly to high concentrations of Methyl Tert-Buthyl Ether (MTBE). Ithas been established that PCE contamination at MW-3S/MW-3D is due to a potential upgradientsource. The source for the MTBE contamination is the former Phillips Petroleum Refinery (nowowned and operated by Holly Refinery and Marketing Co.). Therefore, PCE contamination willbe addressed under the ROD for OU2. MTBE contamination is being addressed under acorrective action program under the oversight of the UDEQ - Division of Water QualityProgram.

TCE is the only contaminant of concern identified in sub-surface soil at OU1. TCE anddegradation products, in the sub-soil (saturated and unsaturated zone) pose a long-term concernas a continuous source to groundwater contamination. The principal reason for concern at OU1is groundwater contamination and the expansion of the plume to residential areas wheregroundwater is being used mainly for irrigation. It must be noted that there may be few caseswhere groundwater is used indoors (DW 26) but, in all the domestic wells where TCE has beendetected, the concentration levels are below the MCLs. Table 3 shows the groundwater resultsfor OU1 sample locations exceeding MCLs.

The COCs in groundwater, the frequency of detection, the range of concentrations, and theexposure point concentrations are presented in Table 8.

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4.3 Exposure Assessment - Hatchco Property

The Hatchco property is currently undeveloped and fenced, minimizing direct human exposure.Exposure within the property boundary is limited to two hypothetical future use scenarios: ahypothetical future worker associated with construction or utilities installation, and ahypothetical future worker inside any building that might be constructed on the property. Aresidential scenario at this property was not considered because the property is currently vacant,is zoned for commercial use and Hatchco intends to develop the land consistent with its currentzoning.

The first exposure scenario at the Hatchco property assumes that an outdoor trench worker maybe exposed to contaminants of potential concern (COPC) during construction of a building. Thisworker is assumed to be involved in construction activities (e.g., digging a foundation, installingutilities) in a 5 feet-deep trench. A trench depth of 5 feet is a conservative estimate based on thefooter depth required for slab-on-grade construction. This estimate includes 32 inches for thefoundation wall, plus a typical 8 inches footer and an additional 12 inches for utility lines to runbeneath the footer. In addition, EPA soil screening guidance cites exposure depths between zeroand one meter for construction activities (i.e., excavation, dozing, grading, tilling). This scenariorepresents the highest exposure potential at OU1.

The potential complete exposure pathways for the trench worker include incidental ingestion ofsub-surface soil and inhalation of VOCs that emanate from sub-surface soil to outdoor air. Thedepth to groundwater at the Hatchco property ranges from 24 to 30 feet bgs; therefore, the trenchworker would not be exposed directly to groundwater. The dermal exposure pathway isconsidered incomplete for all on-site receptors, based on EPA guidance for evaluating dermalexposures to chemicals (EPA/540/R/99/005, July 2004). The guidance does not provide adermal absorption value for VOCs and states that volatile organic compounds would tend to bevolatilized from the soil on skin and should be accounted for via inhalation routes in thecombined exposure pathway analysis.

In the second exposure scenario, the potential exists for a future indoor worker to be exposed toCOPCs via inhalation of VOCs that emanate from sub-surface soil or groundwater to indoor airin a structure that might be built on the Hatchco property. Johnson and Ettinger modeling wasused to estimate indoor air concentrations that might result from volatilization of chemicals insub-surface soil or groundwater through the vadose zone and a building's foundation to theenclosed space. Inhalation of VOCs is the only potentially complete exposure pathway for thisscenario, because the lack of COPCs in surface soils and exposure to soils is not anticipated for ahypothetical future indoor worker due to the nature of indoor worker activities (EPA 2001 a).

4.4 Exposure Assessment • Downgradient of tine Hsntchco Property

Based on the evaluations provided by the OU2 and OU1 risk assessments, only three exposurepathways warranted a quantitative risk evaluation, and are presented in this ROD.

• Direct ingestion of water (from a well) as drinking water

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• Inhalation of VOCs that are released to indoor air from indoor use of groundwater• Inhalation of VOCs that are released from groundwater and migrate through soil into

indoor air

4.5 Human Pathways

4.5.1 Direct Ingestion

As noted in Section 2.5.4, the shallow aquifer is classified by the State of Utah as a Class ndrinking water source. Several domestic wells have been installed in this aquifer and within1,500 feet from the leading edge of the TCE plume. Therefore, it is possible that humans mayingest groundwater as drinking water (Figures 4 and 5). If so, drinking water ingestion is likelyto be a major source of exposure; therefore, this pathway was evaluated quantitatively.

4.5.2 Inhalation of VOCs Released to Indoor Air from Indoor Water Uses

When VOCs are present in water that is used for indoor purposes by residents (e.g., showering,dishwashing, clothes washing, toilets, sinks, cooking) or commercial operations (e.g., processwater), these VOCs may escape from the water into indoor air, leading to inhalation exposure.Measurements and calculations both indicate that this pathway can be significant; therefore, thispathway was evaluated quantitatively for both residents and workers.

4.5.3 Inhalation of VOCs Released from Groundwater to Air Via SoilTransport

Groundwater contaminated with VOCs may release those VOCs into soil gas, and the VOCs maydiffuse upward through pores in the soil and be released at the surface. If the surface is notcovered by a building, the VOCs enter outdoor air where they are diluted and dispersed by wind.Hence, inhalation of VOCs in outdoor air is not considered to be an important exposure route.However, if the VOCs approach the surface at a location near a building, the soil gas may bedrawn into the building and the concentration in the building may tend to build up. Inhalation ofVOCs in indoor air volatilized from soil gas emanating from groundwater and/or sub-surface soilis considered a complete and potentially significant pathway; therefore, this pathway wasevaluated quantitatively.

4.6 Toxicity Assessment

The toxicity assessment considered both carcinogenic and non-carcinogenic effects. Tables 9and 10 provide the exposure parameters and the cancer toxicity information relevant to OU1.The tables list the default exposure parameters recommended by EPA for evaluation of workers'and residents' exposure by ingestion of groundwater and inhalation of VOCs in indoor air. TheBHHRA utilized information from the Integrated Risk Information System (IRIS), EPAProvisional Values, or as cited by EPA-related reports.

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4.7 Risk Characterization

For carcinogens, the risks of cancer from exposure to a chemical are generally expressed as theincremental probability of an individual's developing cancer over a lifetime, 70 years, as a resultof exposure to each chemical. This value is calculated from the average chronic daily intake ofthe chemical from the site, averaged over a lifetime (CDIL), and the slope factor (SF) for thechemical. Excess lifetime cancer risk is calculated from the following equation:

Cancer Risk = CDIL x SF

where:Cancer Risk = a unitless probability (e.g., 2E-04) of an individual's developing cancerCDIL = chronic daily intake averaged over 70 years (mg/kg-day)SF = slope factor, expressed as (mg/kg-day)- 1.

Excess cancer risks are summed across all chemicals of concern and all exposure pathways thatcontribute to exposure of an individual in a given population.

In general, the EPA considers excess cancer risks that are below one in one million (1E-06) to beso small as to be negligible and excess risks above one in ten thousand (1E-04) to be sufficientlylarge to merit some sort of intervention or remediation. Excess cancer risks that range between1E-04 and 1E-06 are generally not considered large enough to warrant action under Superfund(USEPA 1991b), although this is evaluated on a case-by-case basis.

The potential for non-cancer effect is evaluated by calculating the ratio of exposure (GDI) totoxicity level (RfD) for a chemical over a specified time period (e.g., lifetime). The RfDrepresents a level that an individual may be exposed to and not expected to have any harmfuleffects. This ratio is called the Hazard Quotient and is calculated as follows:

= CDIL/RfD

where:

HQ = Hazard QuotientCDIL = Chronic Daily Intake (mg/kg-day) for non-cancer effectsRfD = Reference Dose (mg/kg-day)

If the HQ for a chemical is equal to or less than 1, it is believed that there is no appreciable riskthat non-cancer health effects will occur. If an HQ is greater than 1, there is some possibility thatnon-cancer effects may occur, although an HQ above 1 does not indicate an effect will definitelyoccur. This is because of the margin of safety inherent in the derivation of all RfD values.However, the larger the HQ value, the more likely it is that an adverse effect may occur.

If exposure to the chemical occurs by more than one pathway, the HQ values are added acrosspathways to yield a total indicator risk referred to as a Hazard Index (HI). If exposure occurs tomore than one chemical, and if two or more chemicals act on the same target tissue or organ

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system (e.g., the liver), then the total risk of adverse effects in that tissue is calculated by addingthe HI values across those chemicals.

4.8 Results for Human Receptors

The detailed calculations of cancer and non-cancer risks to humans from exposure togroundwater are presented in Appendix F of the BHHRA. Results are summarized below. Inaccordance with EPA guidance, all risk values are expressed to one significant figure.

As presented in Section 4.2.2 of the BHHRA, there is uncertainty in the oral and inhalation slopefactors for TCE. Thus, a range of slope factors was used to evaluate risks to both residents andworkers. As a consequence, the risk summary tables described below present a range of cancerrisks (minimum and maximum) instead of a single point estimate. For both oral and inhalationexposure, the minimum value is based on the "old" slope factors that were originally establishedin 1987 and then withdrawn from Integrated Risk Information System (IRIS). For oral exposure,the maximum is based on the new oral slope factor (USEP A 2001b), and the maximum forinhalation is based on the assumption that the new inhalation slope factor is equal to the new oralslope factor. Thus, the range of human cancer risks presented in the risk tables in this sectionprovides an index of the range of uncertainty in the cancer risk resulting from exposure to TCE.

4.8.1 Risks from Ingestion of Groundwater

Results for current or future residents and workers are summarized in Table 11. As notedpreviously, it is believed that most residents and workers do not currently ingest water from theshallow aquifer for drinking water. Thus, risks from this pathway are largely hypothetical,although some exceptions may occur. Note that only risks that exceed E-04 are listed on thetables provided in this ROD. Additional information on exposure risks are provided in theBHHRA for each exposure station.

Non-cancer risks from the ingestion of groundwater are below a level of concern in all cases(HI<1) for current or future residents and workers and therefore are not included in this ROD. Atmost locations, excess cancer risks are within or below EPA's target risk range of (1E:04 to 1E-06) for residents and workers. However, there are several stations where cancer risks exceed theupper end of EPA's target risk range. Most of these stations are located within the southernboundary of the Site, including the Holly Refinery, within Study Area 3, the Hatchco property,and in the vicinity of the Hatchco property. Risks in these areas are primarily due to TCE and/orvinyl chloride, with the exception of two locations on or near the Hatchco property (StationsMW-1S and MW-3D) where risks are due to PCE. At one station near the southern boundary ofthe Site, (MW03U), high concentrations (2,400 to 13,000 ug/L) of Methyl Tert-Butyl Ether(MTBE) are the main source of the excess cancer risks. The risk from MTBE contamination isbeing addressed under a corrective action program under the oversight of the UDEQ - Divisionof Water Quality Program.

25

RECORD OF DECISIONBountiful/Woods Cross/5th South PCE Plume NPL Site - Operable Unit J September 2006

4.8.2 Risks from Inhalation of VOCs Intruding from Giroundwater by VaporIntrusion

Intrusion of VOCs from groundwater into indoor air is a complete exposure pathway for currentand future residents and workers. The magnitude of the risk will depend on the concentration ofcontaminants of concern in groundwater underlying the residential or commercial buildings andthe TCE slope factor used in the risk calculations. Detailed calculations of risk from inhalationof VOCs released to indoor air from the vapor intrusion pathway are presented in Appendix F ofthe BHHRA. Results to current or future residents and workers are summarized hi Table 12.

For current or future residents and workers, non-cancer risks from the vapor intrusion pathwayare below a level of concern in all cases (HI<1); therefore, these risks are not included in thisROD. Excess cancer risks are within or below EPA's target risk range of 1E-04 to 1E-06 forresidents at most stations (groundwater at the well head) and for workers at all stations.However, there are a few stations where excess cancer risks to current or future residents fromTCE may exceed 1E-04, depending on which inhalation slope factor is used. These stations arelocated at the Hatchco property and within Study Area 3. However, stations within the Hatchcoproperty are not currently residential, so these risks are hypothetical. Land use within Study Area3 is mixed (commercial and residential), and thus risks to residents could be either current orhypothetical.

4.8.3 Risks from Inhalation of VOCs Released During Indoor Use ofGroundwater

As noted previously, it is believed that most current residents do not use water from the shallowaquifer for indoor purposes, although some exceptions may exist. Thus, risks from this pathwayto residents are mainly hypothetical.

With the exception of station MW03U, non-cancer risks are at or below a level of concern in allcases (HI<1) for current or future residents and workers, and therefore are not discussed in thisROD. At MW03U the non-cancer risk is slightly above a level of concern (HI = 2E+00) forresidents due to MTBE. At most stations, excess cancer risks are within or below EPA's targetrisk range of (1E-04 to 1E-06) for residents and workers. However, as presented in Table 13,there are several stations where cancer risks exceed the upper end of EPA's target risk range.These stations are located in likely source areas. For stations located within Study Area 3, theHatchco property, and at the Holly Refinery, excess cancer risks are primarily due to TCE. Atstations WPH10, DP35, and at several stations near the Hatchco property, vinyl chloride alsocontributes to excess cancer risks.

4.8.4 Combined Risks from All Exposure Pathways

Table 14 presents a summary of the range of risks which might occur if the same resident orworker were exposed by all three of the primary exposure pathways at a well (groundwateringestion, inhalation of VOCs intruding into indoor air from groundwater, and inhalation ofVOCs released to indoor air from indoor water). As seen, excess cancer risks exceed the upper

26


end of EPA's target risk range (1E-04) for residents and workers at several stations. Theseexceedences are due mainly to risks attributable to ingestion of groundwater with lower risksfrom inhalation of VOCs released to air from indoor use of groundwater and inhalation of VOCsintruding from groundwater. In cases where excess cancer risks to residents and workers are dueto TCE, the risks are primarily due to the inhalation of VOCs from the indoor use of groundwaterpathways. With the exception of MTBE, when all exposure pathways are combined, non-cancerrisks are below a level of concern (HI < 1) for workers for all stations; therefore,non-cancer risks are not discussed in this ROD. The source of the MTBE contamination is notattributed to the Hatchco property and is being addressed under UDEQ-DWQ program (UDEQNovember 1, 2005); consequently, MTBE contamination is not subject to the remedy specified inthis ROD.

5.0 Uncertainties

Quantitative evaluation of the risks to human or ecological receptors from environmentalcontamination is frequently limited by uncertainty (lack of precise knowledge) regarding anumber of important exposure and toxicity factors. Thus, exposure and risk calculations areusually derived using a number of estimated values. In general, when data are limited or absent,the exposure and risk parameters selected are chosen in a way that is intentionally conservative.That is, the values selected are more likely to overestimate than underestimate actual risk.However, some assumptions and approaches used in risk assessment may tend to underestimaterisks. It is important for risk managers and the public to keep these uncertainties in mind wheninterpreting the results of a risk assessment. Additional information on the main sources ofuncertainties in the exposure and risk calculations is provided in Section 6.0 of the BHHRA(SRC 2005).

5.1 Summary of Uncertainties

Table 15 summarizes the direction and potential magnitude of the errors introduced by theuncertainties discussed above. Because of these uncertainties, none of the exposure and riskcalculations presented above should be interpreted as accurate measures of the true risk. Rather,all values should be interpreted as uncertain estimates. Because many (but not all) of theapproaches for dealing with uncertainty are intended to be conservative (i.e., are more likely tooverestimate than underestimate), the risk values above should generally be thought of as high-end estimates of the true risk, and actual risks are probably somewhat lower than the calculatedvalues. The exposure assumptions used to calculate risks were, in general, conservative. Thisgenerally results in the overestimation of risks. For several Chemicals of Potential Concern(COPCs), the maximum concentrations were used instead of the 95 percent Upper ConcentrationLimit of the Mean (UCL). This typically results in the overestimation of risk. Quantitative riskcalculations for future residential exposure to groundwater were calculated on the maximallyimpacted wells, or worst-case analysis.

Evaluation of all the uncertainties utilized in the BHHRA suggests that the risks have beenoverestimated. Thus, the EPA's goal to ensure that health risks are not underestimated wasaccomplished.

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Additional information on the main sources of uncertainties in the exposure and risk calculationsperformed are provided in Section 6.0 of the Baseline Human and Ecological Risk Assessmentfor the Bountiful/Woods Cross Site (July 2004).

6.0 Remedial Action Objectives

Remedial Action Objectives (RAOs) for Operable Unit 1 - Hatchco Property were developedfrom a review of the results of the Site-wide sampling data for OU1 and OU2, evaluation of theBHHRA for OU1 and OU2, fate and transport evaluations, and review of Applicable or Relevantand Appropriate Requirements (ARARs).

6.1 Need for Remedial Action

Past operations conducted at the Hatchco property resulted in contamination of sub-surface soilsand groundwater. The key contaminant of concern for sub-surface soils is TCE. The keycontaminants of concern for groundwater include: TCE, PCE, cis-l,2-dichloroethene, VC,naphthalene, benzene and 1,2,4-trimethylbenzene. TCE and its degradation products (DCE andVC) pose the majority of the risk at OU1. MTBE contamination is also present in the OU1groundwater plume, but the source is attributed to the Holly Refinery Marketing Company(former Phillips 66). MTBE contamination is being addressed under a State of Utah Departmentof Environmental Quality, Division of Water Quality Program; consequently, MTBE is notaddressed under this ROD.

The groundwater plume, under current conditions, will continue to expand and potentially couldincrease the contaminant concentrations in groundwater underlying residences and in domesticwells. Active remediation will eliminate or reduce potential exposure pathways for humanreceptors. Effective remediation at OU1 will treat groundwater at the source, at potential hotspots, and will restore groundwater to beneficial uses within a time that is reasonable. Theresponse action selected in this Record of Decision is necessary to protect the public health orwelfare or the environment from actual or threatened releases of hazardous substances into theenvironment.

6.2 Sub-Soil (Saturated Zone) Remedial Action Objective

The RAOs for the sub-soil is to reduce the potential for contaminant migration from sub-soils togroundwater and therefore, to reduce the unacceptable risk to human health and the environment.Based on Soil Screening Guidance (Technical Background Document, EPA, 1996a), the defaultthreshold concentration for TCE in soils is driven by the potential for it to act as a source forgroundwater contamination. The default value is 60 ug/kg (based on a 20-folddilution/attenuation factor). The Remedial Action Objective for the Sub-Soil (saturated zonesoils) is to reduce the potential of the saturated zone soils to act as a source to groundwatercontamination

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RECORD OF DECISIONBountiful/Woods Cross/Sth South PCC Plume NPL Site - Operable Unit 1 September 2006

6.3 Groundwater Remedial Action Objectives

The Remedial Action Objectives at OU1 are:

• Prevent unacceptable exposure risk to current and future human populations posed byingestion of contaminated groundwater, and prevent potential inhalation of VOCsreleased during the indoor use of contaminated groundwater

• Return groundwater to beneficial use if possible or practicable

6.4 Clean-up Goals

The clean-up goals were derived predominantly from the human health risk assessment andARARs. At OU1, the potential cancer risk from exposure to contaminated groundwater exceedsIxlO"6 for residents and workers.

Under the NCP, EPA's goal is to reduce the excess cancer risk to the acceptable range ofto 1x1 CT6. For residential exposures, 1x1 0"6 is the threshold risk factor for making riskmanagement decisions, but risk managers may consider risk factors up to 1x1 0"4 before takingaction. For OU1, EPA selected the MCLs or risk base concentrations based on a hazard index ofone and a cancer risk factor of 1E-4 assuming a Reasonable Maximum Exposure (RME) throughingestion of contaminated groundwater. Chemical-specific cleanup goals for groundwater areprovided in Section 13.2. Non-cancer risks are below a level of concern (HQ < 1). Ecologicalrisks are below a level of concern.

7.0 Description of Alternatives

Several clean-up options and technologies were considered to clean up the groundwater at OU1.This section summarizes each of the nine alternatives selected for detailed analysis in the FinalFocused Feasibility Study Report OU1 (2004). For consistency and clarity, the alternatives arenumbered to correspond with the numbers provided in the FFS report.

7.1 Common Elements

Institutional Controls (ICs)

Each groundwater alternative (except the "No Action") includes ICs to prevent or restrictgroundwater use until the aquifer is returned to beneficial use. Since the remedy will not resultin an unrestricted use and unlimited exposure for the long term, ICs are necessary to limitunacceptable exposures at OU1.

The principal Site concern at OU1 is the ingestion of groundwater contaminated with PCE, TCE

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degradation products (DCE, VC), and the potential inhalation of VOC vapors from groundwaterthat could accumulate in indoor spaces. The target areas for potential future inhalation concernsare where new residential or commercial structures may be constructed and the current residentialareas located downgradient from the current extent of the groundwater plume. Groundwatermodeling can be used to predict the correlation between solvent plumes and VOC accumulationin buildings. However, modeling alone is usually not a reliable indicator where buildings arelocated above solvent plumes. Groundwater monitoring coupled with soil vapor intrusion testingwill alert the agencies of the potential vapor intrusion impacts to current and future residentialareas. ICs (including land use controls, restricting groundwater uses on domestic wells, ormunicipal wells, restricting new well development, or requiring mitigation for vapor intrusion,)may be used to eliminate these potential exposure pathways. These ICs are a common element toall alternatives presented in this ROD. The objectives of the ICs are presented below:

ICs Objectives

1) Restrict the use of groundwater as a drinking water source until the MCLs are met;2) Restrict new well development for drinking water and domestic use along the

projected path of the contaminated groundwater plume; and,3) Recommend vapor intrusion mitigation in all permits for new construction of

commercial (office space) and/or residential buildings planned on or along theprojected path of the contaminated plume.

Implementation of ICs will be the result of agreements with the State and the appropriate localjurisdictions. Details on the proposed ICs for the Site generally will be presented to the publicvia the Proposed Plan for OU2. None of the remedies rely exclusively on ICs to achieveprotectiveness.

Monitoring

Except for the "No Action" alternative, groundwater monitoring (as well as ICs monitoring) is acommon element to all alternatives. Monitoring is a key component to ensure protection ofhuman health and the environment and to measure the effectiveness of the remedy.

7.2 Alternative 1 - No Action Alternative

Estimated construction time frame: NoneRegulations governing the Superfund program require that the "no action" alternative beevaluated generally to establish a baseline for comparison. Under this alternative, EPA wouldleave soil and groundwater in its current condition and would not take any action at OU1 toprevent human exposure to groundwater or to prevent further degradation of groundwaterresources. The source material and contaminated groundwater would be left in place withouttreatment, allowing continued migration of the contaminants of concern. Any reduction ingroundwater concentrations would be due to natural migration, dispersion, attenuation, anddegradation processes.

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7.3 Alternative 2 - Monitored Natural Attenuation (MNA) With InstitutionalControls

Estimated construction timeframe: 6 monthsEstimated date range to achieve clean-up objectives downgradient from the Hatchco property:2022 to 2057 - based on groundwater modeling for the TCE plume (FS Report, 2004).This alternative allows natural processes to restore groundwater to a beneficial use. Under thisalternative the concentrations of VOCs would be reduced to Safe Drinking Water standards(MCLs). Long term groundwater monitoring will be required to demonstrate MNA,contaminants degradation rates and to ensure the effectiveness of the remedy.Estimated Present Worth Cost (2003 estimate): $67,998.00

7.4 Alternative 3 - Surface Capping with Institutional Controls

Estimated construction timeframe: 6 monthsEstimated time to achieve clean-up objectives: Shorter time frame than under Alternatives 1 and2. This alternative involves installing a low-permeability barrier over the area on the Hatchcoproperty that contains contaminated sub-soils. The barrier would minimize the potential for rain,snow melt or irrigation water to seep through contaminated soils and into groundwater. Capmaterial may include a building footprint, geomembrane, compacted clay, concrete, asphalt orsome combination of these.Estimated Present Worth Cost (2003 estimate): $147,207.00

7.5 Alternative 4 - Soil Vapor Extraction with Institutional Controls

Estimated construction timeframe: 6 monthsEstimated time to achieve clean-up objectives: Shorter time frame than alternatives 1, 2 and 3. Itis assumed that the Soil Vapor Extraction (SVE) system will operate for five years.This alternative calls for the construction of a soil vapor extraction system to removecontaminants from vadose zone soils (unsaturated soils above the groundwater table). The systemwould require multiple vertical soil gas recovery wells or several lengths of slotted pipe installedin the target treatment area. A vacuum would collect vapors and discharge them directly into theatmosphere.Estimated Present Worth Cost (2003 estimate): $316,644.00

7.6 Alternative 5 - Excavation with Offsite Disposal

This alternative was rejected during the screening process due to the quantity of overburden soilto access the relative thin and potentially discontinuous layer of contamination, and the high costwhen compared to the other alternatives.

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7.7 Alternative 6 - Enhanced In-Situ Biological/Chemical Remediationwith Institutional Controls

Estimated construction timeframe: 6 monthsEstimated time to achieve clean-up objectives: According to the FFS, it will take shorter timeframe than alternatives 1, 2, 3, and 4; however, based on a Technical Memorandum - CostEstimate for Full-scale Remediation at OU1 (September 18, 2006), the groundwater remedy forOU1 may be completed in as few as 4 years at the source area and 15 years in the plume to aslong as approximately 50 years depending on the rate of MNA in the plume fringe. Under thisalternative, a substance (electron donor i.e., emulsified soybean oil) would be injected into theaquifer to stimulate bacteria activity and speed up the breakdown of the VOCs. The overallpurpose of this alternative would be to stimulate the breakdown of VOCs at the source, toaccelerate the degradation rates of contaminants of concern in the saturated zone, groundwater,and prevent the expansion of the groundwater plume (Figure 12).Estimated Present Worth Cost (2003 estimate): $328,800.00

7.8 Alternative 7a - Treatment via Air Stripping With Institutional Controls

Estimated construction timeframe: 6 monthsEstimated date to achieve clean-up objectives in the off-site area: Shorter time frame thanalternatives 1, 2, 3, and 4.This alternative involves capturing contaminated groundwater onsite without adversely affectinga petroleum plume, which originates to the north outside the Hatchco property. An extractionwell located near the west property boundary would remove contaminated groundwater. Theextracted water would cascade over a column designed to distribute the contaminated water intoa thin film. Air would be blown up through the column. The air would cause the VOCs tovaporize and be carried out the column into the atmosphere. Treated groundwater would bedischarged to surface water via the storm sewer.Estimated Present Worth Cost (2003 estimate): $335,409.00

7.9 Alternative 7b - Treatment via Ultraviolet Oxidation With InstitutionalControls

Estimated construction time frame: 6 monthsEstimated date to achieve clean-up objectives in the off-site area: Shorter time frame thanalternatives 1, 2, 3, and 4.The extraction system would be the same as Alternative 7a. The groundwater would be treatedvia an ultraviolet oxidation (UV) process. Hydrogen peroxide would be injected in the extractedgroundwater prior to the UV light treatment. The VOCs are destroyed in the UV oxidationprocess. Treated groundwater would be discharged to surface water via the storm sewer system.Estimated Present Worth Cost (2003 estimate): $625,705.00

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7.10 Alternative 7c - Discharge to Public Owned Treatment Works (POTW)With Institutional Controls

Estimated Construction Time frame: 6 monthsEstimated date to achieve clean-up objectives in the off-site area: Shorter time frame thanalternatives 1, 2, 3, and 4.The extraction system is the same as Alternative 7a. The untreated groundwater would bedischarged to the South Davis Sewer District Facility. Extracted groundwater would beconveyed via a pipe to a point within the District's system. Contaminant toxicity, mobility, andvolume would be reduced through treatment at the POTW.Estimated Present Worth Cost (2003 estimate): $206,556.00

7.11 Summary

The Present Worth Cost was estimated to mitigate groundwater contamination emanating fromthe Hatchco property only. The cost did not include an estimate to remediate potential hot spotsor potential secondary sources. Except for the "No Action" alternative, in the long-term, allalternatives are expected to attain the Cleanup Goals. For additional information, details on eachalternative are available in the Final Focused Feasibility Study Report (July 2004)

8.0 Comparative Analysis of Alternatives Criteria

The NCP requires that each remedial alternative analyzed in detail in the FS documents beevaluated according to specific criteria. The purpose of this evaluation is to promote consistentidentification of the relative advantages and disadvantages of each alternative, thereby guidingselection of remedies offering the most effective and efficient means of achieving the OU1 clean-up goals. There are nine criteria by which feasible remedial alternatives are evaluated. While allnine criteria are important, they are weighted differently in the decision-making processdepending on whether they describe or involve protection of human health and the environmentor compliance with Federal or State statutes and regulations (threshold criteria), a considerationof technical or socioeconomic merits (primary balancing criteria), or the evaluation of non-EPAreviewers that may influence an EPA decision (modifying criteria).

Threshold Criteria(1) Overall Protection of Human Health and the Environment(2) Compliance with Applicable or Relevant and Appropriate Requirements

(ARARs)

Primary Balancing Criteria(3) Long-term Effectiveness and Permanence(4) Reduction of Toxicity, Mobility, or Volume of Contaminants through

Treatment(5) Short-term Effectiveness

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(6) hnplementability(7) Cost

Modifying Criteria(8) State acceptance(9) Community acceptance

8.1 Evaluation of the Proposed Alternative

8.1.1 Overall Protection of Human Health and the Environment.

Overall protection of human health and the environment addresses whether each alternativeprovides adequate protection of human health and the environment and describes how risksposed through each exposure pathway are eliminated, reduced, or controlled, through treatment,engineering controls, and/or ICs.

With ICs, all the alternatives, except the "no action" alternative, would adequately protect humanhealth and the environment by eliminating, reducing, or controlling risk through treatment,engineering controls, and/or ICs. The VOCs are either treated to safe levels, or over time breakdown to safe levels through natural processes. It should be noted that for the remedy to beprotective during the time it will take to reach safe levels, all the alternatives rely on ICs. Table16 presents a summary of the comparative analysis of alternatives.

With the exception of Alternative 2 - Monitored Natural Attenuation (MNA), and Alternative 3 -Surface Capping, all groundwater alternatives would eliminate human exposure risks from directcontact with contaminated groundwater through treatment.

Alternatives 2 and 3 do not prevent contaminants at the source area from flowing down gradientof the Hatchco property. Alternative 3 - Surface Capping, would reduce infiltration by seepingrain, snow melt, or irrigation; therefore, reducing oxygen delivery through some elimination ofrecharge. While capping would enhance reductive dechlorination of the parent compounds(PCE, TCE), it may decrease the degradation rate of DCE and VC, and allow these compounds toeventually discharge into groundwater. Capping of contaminated soils would reduce the amountof contaminants leaching into groundwater and would allow natural processes to eventuallymitigate or significantly reduce the levels in the soils. Because capping does not fully contain thesource material and regional groundwater levels fluctuate severely (depending on regionalprecipitation and changes in water table elevations), Alternative 3 may not reach the clean-upobjectives in a time effective manner and may actually increase the time to achieve groundwaterrestoration.

Because the "no action" alternative is not protective of human health and the environment, it willbe eliminated from further consideration. The uncertainties associated with Alternative 3 -"Capping" as a stand alone remedy also warrant dropping it from further evaluation.

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8.1.2 Compliance with Applicable or Relevant and AppropriateRequirements (ARARs)

Section 121(d) of CERCLA and 40 C.F.R. §300.430(f)(l)(ii)(B) of the NCP require that remedialactions at CERCLA sites at least attain legally applicable or relevant and appropriate federal andstate requirements, standards, criteria, and limitations, which are collectively referred to asARARs, unless such ARARs are waived under CERCLA 121(d)(4).

All remaining alternatives would meet their respective State and federal ARARs. See Tables 17and 18.

8.1.3 Long-term Effectiveness and Permanence

This criterion evaluates the ability of an alternative to maintain protection of human health andthe environment over time. The long-term effectiveness of the alternatives relies heavily on ICsfor protection of human health. They also rely to a significant degree on natural processes toattain clean-up objectives. Alternatives 7a & 7b are effective in the long-term by reducingcontaminant concentrations in groundwater. Pump and treatment technologies have proven to beeffective for treating VOCs in groundwater. Alternatives 7a, 7b and 7c would also have low,long-term risks, but the remedy would take longer to achieve the clean-up objectives.

Alternative 2 - Monitored Natural Attenuation, has some uncertainty with regard to itseffectiveness and the time required to reach final clean-up levels. Alternative 4 - Soil VaporExtraction, would reduce contaminant concentrations in the unsaturated zone above thegroundwater table but would continue to allow contaminated groundwater to migrate until theclean-up objectives are met. The groundwater treatment alternatives offer a high degree ofpermanence once the clean-up objectives are met.

Alternative 6 - In-Situ Biological/Chemical Remediation, would have the greatest long-termeffectiveness. This alternative would accelerate the natural destruction of VOCs at the sourcearea and in the shallow aquifer. Alternative 6 would decrease the time needed to achieve clean-up objectives at OU1. Alternative 6 treatment technology is permanent, so the long-termpotential exposure risk would be low.

8.1.4 Reduction ofToxicity, Mobility, or Volume of Contaminants throughTreatment

This criterion considers the use of treatment to remove, reduce or destroy the harmful effects ofthe contaminants. Alternative 2 - Monitored Natural Attenuation, does not use treatment toreduce or destroy the VOCs. The alternative relies on natural processes to degrade thesesubstances to non-harmful effects. Reduction of toxicity, mobility or volume would be achievedthrough a natural breakdown process. Alternative 4 - Soil Vapor Extraction, would reducetoxicity, mobility and volume at the source to some extent and consequently in the groundwater.Contaminant mass reduction would be limited to the unsaturated zone above the groundwatertable. Contaminant mobility will increase by discharging recovered soil gas into the atmosphere,

35


although it is anticipated that the overall impact will be negligible.

Alternative 6 - In-Situ Biological/Chemical Remediation, would enhance the natural breakdownof the VOCs at the source and in groundwater, thereby accelerating the reduction of toxicity,mobility or volume of COCs. Alternative 7a - Air Stripping, contaminant mobility wouldincrease VOCs to the atmosphere. Alternative 7b - Ultraviolet Oxidation, would reduce thecontaminant toxicity, mobility or volume through the destruction of the VOCs. Alternative 7c -Discharging Untreated Groundwater to the South Davis Sewer District (the District) Facility,does not treat the VOCs, instead it relies on the District to handle the contaminated groundwaterallowing the District reduce the contaminant toxicity, mobility or volume through treatment atthe publicly owned treatments works (POTW). In the long-term, the portion of alternatives 7a,7b and 7c subjected to natural breakdown processes would also attain reduction in toxicity,mobility, or volume of VOCs thru treatment and natural processes.

8.1.5 Short-term Effectiveness

Short-term effectiveness addresses the period of time needed to implement the remedy and anyadverse impacts that may be posed to workers, the community, and the environment duringconstruction and operation of the remedy until cleanup levels are achieved.

There are no short-term risks associated with Alternative 2 - Monitored Natural Attenuation.Risks associated with Alternative 4 - Soil Vapor Extraction, and Alternative 7a - Air Stripping,involve the discharge of contaminants at low levels into the atmosphere. This action wouldslightly increase potential health risks to the surrounding community; however, the increased riskwould be negligible.

There are no short-term risks associated with implementing Alternatives 6, 7b and 7c.Short-term risk to workers associated with normal construction hazards and potential contactwith contaminated water will be eliminated through appropriate controls and use of proper healthand safety protocols.

8.16 Implementability

This criterion addresses the technical and administrative feasibility of a remedy from designthrough construction and operation. Factors such as availability for services and materials,administrative feasibility and coordination with other governmental entities are also considered.

All treatment technologies and remedies are readily available, generally proven, and are equallyimplementable without construction difficulties. There is a potential for operation andmaintenance problems associated with alternatives 4, 7a, 7b and 7c. Alternative 7c - Dischargingto the POTW does not treat the VOCs on-site, instead it relies on the District to handle thecontaminated groundwater. Because the District may not allow untreated contaminated water tobe discharged into its system, this alternative may not be implementable.

36


8.1.7 Cost

It should be noted that the estimated present worth cost, calculated by Hatchco to clean up thecontaminants originating at the Hatchco property, represented the response cost of only a portion(approximately one-half) of the groundwater plume. Hatchco's determination was based on July14,2003 data and on the premise of a potential a secondary source. However, results from theCDM RI for OU2 did not support the presence of a secondary TCE source of groundwatercontamination. EPA's 2006 cost estimate is based on the present worth cost to remediate theentire TCE plume and includes contract requirements and obligations not anticipated by Hatchco.Cost information to implement the selected remedy is provided in Section 12.0. Table 16,provides a cost comparison of each alternative as they were evaluated in Hatchco's 2004 FFSreport.

8.1.8 State Acceptance

The State of Utah, UDEQ, participated in the development and review of the remedialinvestigation/feasibility study and the pilot study implementation. UDEQ provided technicalcomments and oversight support to all the sampling and field activities as they relate to OU1.

UDEQ supports a combination of Alternative 2 - Monitored Natural Attenuation, and Alternative6 - Enhanced In-Situ Biological/Chemical Remediation with Institutional Controls. UDEQ hasindicated that it believes that the selected remedy can accomplish the remedial action objectivespresented in this ROD. UDEQ will continue to work with EPA and the cities of Bountiful andWoods Cross to ensure the remedy is protective.

8.1.9 Community Acceptance

This criterion evaluates whether the local community agrees with EPA's analyses and preferredalternative.

Because no written comments were received on the Proposed Plan from the community, and onlya few comments were provided in the public meeting, it is difficult to determine communityacceptance of the alternatives. There were no vocalized objections to any of the alternatives. Atthe public meeting, one person was concerned with the groundwater plume and the impact on herproperty. EPA explained that the property of interest was outside the boundary of the OU1groundwater plume.

On August 21, 2004, the PRP requested an extension to the public comment period to allow themadequate time to comment. An extension was granted until October 7, 2004. The PRPsubmitted comments to EPA on October 8, 2004. Most of the comments were related to thetechnical aspects of the project and to challenge EPA's preferred alternative. Responses towritten comments received are included in the responsiveness summary section of this report.

37


9.0 Principal Threat Wastes

The NCP establishes an expectation that EPA will use treatment to address the principal threatsposed by a site wherever practicable (NCP, 40 C.F.R. §300.430(a)(l)(iii)(A)). Identifyingprincipal threat waste combines concepts of both hazard and risk. In general, principal threatwastes are those source materials that include and contain hazardous substances, pollutants orcontaminants that act as a reservoir for contamination to groundwater, surface water, or ah", or actas a source for direct exposure. The source material in the sub-surface soil at OU1 is consideredto be highly toxic and highly mobile, which generally cannot be contained in a reliable manner orwould present a significant risk to human health or the environment should exposure occur. Thesub-soil at the Hatchco property is contaminated and is considered to be principal threat wastesbecause the chemicals of concern are found at concentrations that pose a significant risk to eitherhuman health or the environment should exposure occur.

10.0 Selected Remedy

10.1 Summary of the Rationale for the Selected Remedy for GroundwaterContamination

The Selected Remedy for OU1 for cleaning up the PCE/TCE groundwater plume is acombination of Alternative 2 - Monitored Natural Attenuation with Institutional Controls, andAlternative 6, Enhanced In-Situ Biological/Chemical Remediation. The combination of thesealternatives would achieve all clean-up objectives by preventing exposure to groundwater andincreasing the breakdown rate of VOCs (PCE/TCE) in the source material located in thesaturated zone and groundwater through treatment. Groundwater monitoring and institutionalcontrols would be required until the RAOs are met.

The monitored natural attenuation alternative (Alternative 2) was selected to monitor the naturaldegradation parameters to ensure that the plume emanating from the Hatchco property woulddecrease over time once the source material in the saturated zone and potential hot spots areremediated. Remediation is needed at OU1 because the evidence of natural attenuation ingroundwater is limited (no significant decrease in groundwater concentrations over time isevident in any well), see Table 5. However, the presence of breakdown products coupled withgroundwater modeling suggests that some natural breakdown is occurring, favoring the potentialfor natural attenuation.

EPA selected Alternative 6 over the other alternatives because it will accelerate the breakdown ofVOCs at the source area. This alternative will achieve substantial risk reduction throughtreatment/destruction of contaminants in groundwater at the source, in the saturated zone, and thepotential hot spots downgradient of the Hatchco property. Alternative 6 will more quicklyreduce the risk of potential human exposure to contaminated groundwater and will accelerate thetime needed to restore the aquifer to beneficial uses. The combination of Alternatives 2 and 6,hereafter referred to as the Selected Remedy, reduces the risk within a reasonable time framewhen compared to the other alternatives, provides for long-term effectiveness of the remedy and

38

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCC Plume MPL Site - Operable Unit 1 September 2006

3. Recommend vapor intrusion mitigation in all permits for construction of new commercial(office space) and/or residential buildings planned on or along the projected path of thecontaminated plumes

11.2 Step 2 - Monitoring

Design a long-term groundwater monitoring plan to assess the effectiveness of in-situ treatmentprocess, the natural attenuation processes, and the effectiveness of the Selected Remedy. Thelong-term groundwater monitoring plan will be developed during the remedial design phase forOU1. A groundwater baseline for the entire TCE plume will be required prior to implementingthe remedial action. Based on groundwater modeling, additional monitoring wells will beinstalled at selected intervals to understand the interaction between MNA and the in-situbioremediation. All the groundwater samples will be analyzed for VOCs and MNA parametersaccording to EPA MNA guidance and the long-term groundwater monitoring plan. It is assumedthat two wells will be installed to monitor groundwater upgradient of the domestic wells. Thesewells will be used to alert EPA and/or UDEQ to either increase or decrease the level ofinstitutional controls, (i.e., increase groundwater use restrictions, coupled with monitoring forvapor intrusion from groundwater). Groundwater monitoring will be required during the firstfive years after the initiation of the remedial action. The data will be evaluated annually until thefirst five-year review. During the five-year review, EPA, in consultation with UDEQ willevaluate the data and continue or opt to modify the groundwater monitoring plan for thesubsequent five-year review period.

11.3 Step 3 - Well Abandonment

All the monitoring wells not selected for the long-term monitoring program will be abandonedaccording to the State of Utah's well abandonment requirements.

11.4 Step 4 - Groundwater Treatment

Injections of bioremediation amendments (injection of an electron donor i.e., emulsified soybeanoil to stimulate the microbial community) will start at the source area and at one biobarrierdowngradient from the source area. This first biobarrier will immediately contribute todecreasing plume concentrations, as well as ensuring that any contaminant degradation productsnot completely destroyed in the source area are effectively polished. After the first two years ofoperations it is assumed that an additional electron donor injection event will be requiredthroughout the source area and the first biobarrier. In addition, in order to mitigate hotspots, it isanticipated that two additional biobarriers will be installed in the plume downgradient from thefirst biobarrier. Additional biobarrier injections to recharge the electron donor supply areanticipated 4 years and 6 years after the original injection. This will result in a total of twoelectron donor injections throughout the source area, and three in each of the biobarriers. Thisstrategy may be modified based on the data collected during the remedial action. Groundwaterwill be monitored according to the long-term monitoring plan. At the end of the first five-yearreview EPA, in consultation with UDEQ, will evaluate the effectiveness of the remedy and theneed for additional injections of amendments.

40


will cost less than the active groundwater treatment alternatives presented in the FFS (FFS-2003).

Since the remedy leaves contaminants in place until the clean-up objectives are achieved, EPAwill conduct five-year reviews as required by statute until contaminant levels at the source andgroundwater do not pose an unacceptable risk to human health and the environment. Duringeach five-year review, EPA will review the monitoring data, and will modify the groundwatermonitoring plan as appropriate to ensure the information gathered continues to support thecleanup objectives.

Based on the information available at this time, EPA and the State of Utah, Department ofEnvironmental Quality, believe that the Selected Remedy will be protective of human health andthe environment, will comply with ARARs, will be cost effective, will achieve permanentsolutions, and use alternative treatment technologies to the maximum extent practicable.

11.0 Description of the Selected Remedy

A pilot study was initiated in July 2005 (Pilot Study Implementation Plan July-2005) to collectdata necessary to support the ROD and the design of the selected remedy. Three specificobjectives contributed to the overall purpose of the pilot test:

• Determine substrate requirements• Determine the injection strategy• Determine the biodegradation capability of the indigenous microbial community

The data generated by the pilot study support the Selected Remedy and will provide the basis forthe remedial design. A description of the selected remedy in the sequence that is expectedfollows:

11.1 Step 1 - Institutional Controls (ICs)

Since contaminants of concern will remain in groundwater until the remedy is completed, ICswill be required to protect the public health and the environment. Results from the RI/FS forboth OU1 and OU2, for the short and the long term do not allow for unrestricted groundwater useand unlimited exposure; therefore, ICs are necessary to limit unacceptable exposure resultingfrom contaminants emanating from OU1 and OU2. EPA will work with the State of Utah,UDEQ, and local jurisdictions to set reliable ICs for the entire NPL Site. The ICs will remain inplace until the groundwater quality improves to allow for unrestricted use.

The combined ICs objectives for both OU1 and OU2 are:

1. Restrict the use of groundwater as a drinking water source until the MCLs are met

2. Restrict new well development for drinking water and domestic use along the projectedpath of the contaminated groundwater plume

39


11.5 Step 5 - Exit Strategy

Groundwater and MNA monitoring will continue until the performance standards are reached fora period of two consecutive years. Once EPA, in consultation with UDEQ, concludes thatgroundwater quality has improved to allow for unrestricted use (results at or below MCLs), theremedy shall terminate.

12.0 Summary of the Estimated Remedy Costs

The Selected Remedy is expected to cost approximately $1.69M (Table 19) depending on theeffectiveness of bioremediation amendments, the degree of natural attenuation, and thedegradation capability of the microbial community. It is anticipated it will take about 4 years toreduce groundwater concentrations to levels that will be conducive for MNA in the source area.In the plume, the biobarriers are anticipated to reduce groundwater contaminant concentrations tolevels conducive to MNA in about 8 years. Groundwater monitoring is expected to be requiredfor at least 15 years. While the bioremediation activities will directly address the highconcentration core of the plume, the lower concentration fringe will be treated solely throughMNA. Given the concentrations in the plume fringe, approximately 6-7 half-lives will berequired to meet MCLs. The time that will be required, and the impact that will have on themonitoring time period will be further evaluated during the remedial design.

13.0 Expected Outcomes of the Selected Remedy

13.1 A variable Land Use A fter site Cleanup

After the groundwater is cleaned up (at or below MCLs for a period of two consecutive years) theremedy will be completed. Institutional controls restricting groundwater use shall be evaluatedagainst the ICs needed for OU2 and may remain in place until the completion of the remedy forOU2. Based on a Technical Memorandum - Cost Estimate for Full-scale Remediation at OU1(September 18, 2006), the groundwater remedy for OU1 may be completed in as few as 4 yearsin the source area and 15 years in the plume to as long as approximately 50 years depending onthe rate of MNA in the plume fringe. Until the groundwater remedy is complete, restrictions willbe required to prevent the groundwater from being used indoors or as a drinking water source.The potential land that will be available for unrestricted use after OU1 is cleaned up is 42 acres.

13.2 Clean-up Levels

The clean-up levels are based on unrestricted groundwater use, MCLs and MCL goals (MCLG).CERCLA Section 121(d)(2)(A)(ii) and NCP, 40 C.F.R. §300.430(e)(i)(B) directs that MCLGs,set at a level above zero, may be relevant and appropriate remedial actions involving ground orsurface water that are currently or potential sources of drinking water. If the MCLG is zero, thecorresponding MCL will be relevant and appropriate instead. EPA and UDEQ have adopted theNational Primary Drinking Water Standards 40 CFR Part 141 FR 8750 (MCLs) as thegroundwater clean-up levels for the OU1 plume. The values of the contaminants of concern are

41

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCE Plume iNPL Site - Operable Unit 1 September 2006

health based standards for public drinking water systems and are listed below:

Groundwater Clean-up Levels

Chemical

Trichloroethene

Tetrachloroethene

Vinyl chloride

Cis-1, 2-dichloroethene

Benzene

napthalene

1 ,2,4-trimethylbenzene

MCUMCLG3-15

(ug/L)

5 / 0

5 / 0

2 / 0

70/70

5 / 0

NA

70

State Groundwatef .Quality Standards

. (ug/L) ; •-• • ;

5

5

2

70

5

NA

70

•-.'.' . • :VX""~:''\!,'j::;s'-i5''~.:/;-J Preliniinary^ ^ -v :-'.>

...**'•'•"'•" ' . . . . . • -''--1 .-."-. .-1 ';RemedialtottGoal :

^g^--"fSS: :

5

5

2 '

70

5

6.5

70aLand use at the OU1 source is expected to be commercial/industrial.b Land use out side the Hatchco property is expected to be cornmercial/industrial/agricultural or residential.

13.3 Statutory Determinations

Under CERCLA 121 and the NCP, the lead agency must select remedies that are protective ofhuman health and the environment, comply with applicable or relevant and appropriaterequirements (unless a statutory waiver is justified), are cost-effective, and provide permanentsolutions to the extent practicable. In addition, CERCLA includes a preference for remedies thatemploy treatment that permanently and significantly reduces the volume, toxicity, or mobility ofhazardous wastes as a principal element and a bias against offsite disposal of untreated waste.The following sections present how the Selected Remedy meets the statutory requirements:

13.4 Protection of Human Health and the Environment

The Selected Remedy will adequately protect human health and the environment throughtreatment, engineering controls, and/or institutional controls (NCP, 40 C.F.R. §300.430(f)(5)(ii)).The remedy will prevent unacceptable risks to current and future populations presented by directcontact, or ingestion of contaminated groundwater and the potential inhalation of vaporsemanating from groundwater to indoor air. Contaminated groundwater will be treated andmonitored until the contaminants of concern for OU1 are at or below federal MCLs. EPA inconsultation with UDEQ will issue notices to City officials and property owners on the status of

42


the contaminated groundwater. The notices will be issued annually until the groundwater isreturned to unrestricted use. ICs as discussed in Section 7.1 will be implemented to controlexposures until the clean-up levels are met. These actions will reduce the risks to human healthand are not expected to cause unacceptable short-term risks.

13.5 Compliance with Applicable or Relevant and AppropriateRequirements

Section 122(d) of CERCLA and NCP, 40 C.F.R. §300.430(f)(l)(ii)(B) require that actions atCERCLA sites at least attain legally applicable or relevant and appropriate federal and staterequirements, standards, criteria, and limitations which are collectively referred to as "ARARs",unless such ARARs are waived under CERCLA Section 121(d)(4). Applicable requirements arethose substantive environmental protection requirements, criteria, or limitations promulgatedunder federal or state law that specifically address hazardous substances, the remedial action tobe implemented at the site, the location of the site, or other circumstances present at the site.Relevant and appropriate requirements are those substantive environmental protectionrequirements, criteria, or limitations promulgated under federal or state law which, while notapplicable to the hazardous materials found at the site, the remedial action itself, the site location,or other circumstances at the site, nevertheless address problems or situations sufficiently similarto those encountered at the site that their use is well suited to the site.

There are three types of ARARs: chemical-specific; action-specific; and location-specific.Chemical-specific ARARs may determine clean-up levels for specific chemicals or dischargelimits. Action-specific ARARs establish controls or restrictions on the remedial activities thatare part of the remedial solution. Action-specific ARARs are triggered by the specific remedialactivity rather than the contaminants present. Location-specific ARARs set limitations onremedial activities as a result of the site's location or characteristics (such as being located in aflood plain). Also considered at the time ARARs are established are policies, guidance, andother sources of information which, though not enforceable, are "to be considered" in theselection of the remedy and the implementation of the ROD. These "to be considered" standardsmay provide additional important benchmarks that can be considered in selecting a remedy.

The chemical-specific ARARs for the OU1 include: Safe Drinking Water Act of 1974,42 U.S.C.Section 300(f) et seq., as amended in 1986 - establishes chemical-specific standards, applicableat the tap. Under the NCP, 40 C.F.R. §300.430(e)(2)(i)(B), these standards are relevant andappropriate to a cleanup of groundwater which is a current or potential source of drinking water.The SDWA's maximum contaminant level (MCL) is used for any contaminant whose maximumcontaminant level goal (MCLG) is zero; otherwise, the MCLG is used. Table 17 provides a listof the chemical-specific ARARs that apply to OU1.

The action-specific ARARs for the selected alternatives are set out in Table 18. There are noLocation Specific ARARs for OU1. The selected alternative will comply with all ARARs.

43


13.6 Cost Effectiveness

The Selected Remedy meets the statutory requirement that all Superfund remedies be cost-effective. A cost-effective remedy in the Superfund program is one whose "costs areproportional to its overall effectiveness" (NCP, 40 C.F.R. §300.430(f)(l)(ii)(D)). The "overalleffectiveness" is determined by evaluating the following three of the five balancing criteria usedin the detailed analysis of alternatives: (1) Long-term effectiveness and permanence; (2)Reduction in toxicity, mobility and volume (TMV) through treatment; and, (3) Short-termeffectiveness. The overall effectiveness of the Selected Remedy is cost-effective and, therefore,represents a reasonable cost vs. benefit value. For determination of cost effectiveness, a costeffectiveness matrix was utilized in the FFS. In the matrix, the alternatives were listed in orderof increasing costs. For each alternative, information was presented on long-term effectivenessand permanence, reduction of toxicity, mobility and volume through treatment, and short-termeffectiveness. The information in those three categories was compared to the prior alternativelisted and evaluated as to whether it was more effective, less effective, or of equal effectiveness.When considering the entire TCE plume extend (approximately 42 acres), the Selected Remedyis considered to be cost effective, because it is a permanent solution that reduces risks to humanhealth to acceptable levels. A cost-effectiveness analysis of all the alternatives to treat the entireTCE plume was not included in the final analysis; however, it is anticipated that the cost will beproportional to the 2003 cost analysis when applied to the entire TCE plume. Therefore, it isestimated that the Selected Remedy cost would be less than or equal to the cost of some of theother permanent, risk-reducing alternatives.

13.7 Utilization of Permanent Solutions and Alternative Treatment (orResource Recovery) Technologies to the Maximum Extent Practicable(MEP)

The Selected Remedy represents the maximum extent to which a permanent solution andinnovated treatment technologies can be used with a practical outcome at OU1. Of all thealternatives considered, the Selected Remedy provides the best balance of the five balancingcriteria, provides for the statutory preference for treatment as the principal element, and isaccepted by the State and community.

13.8 Preference for Treatment as a Principal Element

The Selected Remedy for groundwater includes treatment of the saturated zone soil in the sourcearea. The contaminated sub-surface soil at the source area contains high concentrations ofsubstances that are highly toxic and mobile and act as a reservoir for contaminants to move intogroundwater. In-situ treatment of the saturated portion of the source will accelerate thedegradation rate of the contaminants of concern and will reduce the impact to groundwater andthe potential impact to domestic wells located down gradient from the leading edge of the plume.

44


13.9 Five Year Review Requirements

Because the Selected Remedy will not treat the sub-soils in the source area, above thegroundwater table, contaminants may persist to leach into groundwater for an undetermined time.These sub-soils may continue to release hazardous substances, pollutants, or contaminants intogroundwater; therefore, it may take more than five years (see Section 7.7) to meet the remedialaction objectives and clean-up levels. A statutory review will be conducted within five yearsafter the first electron donor/bioaugmentation injection (initiation of the remedial action) toensure that the remedy is or will be protective of human health and the environment. Five yearreviews will continue until the clean-up objectives are met.

14.0 Documentation of Significant Changes from Preferred Alternative ofProposed Plan

The Proposed Plan for the Bountiful/Woods Cross/5th South PCE Plume Operable Unit 1 (OU1)was released on August 2004. The initial public comment period was from August 7, 2004 toSeptember 7, 2004 and the public meeting took place on Tuesday, August 24, 2004. On August23, the PRP requested an extension to the public comment period. The extension was granteduntil October 7, 2004. The Proposed Plan identified the preferred alternatives, MonitoredNatural Attenuation and In-Situ Biological/Chemical Remediation, which are also the SelectedRemedy for this ROD. The Proposed Plan also included the State's support for the SelectedRemedy. EPA reviewed the verbal comments submitted during the public meeting, which wastranscribed by a court reporter. No written comments were received by EPA during the first 30days of the public comment period. Three general comments and 17 specific comments werereceived from the PRP on October 8, 2004. It was determined that no significant changes to theselected preferred alternative were necessary or appropriate. The remedy selected in this ROD isconsistent with the preferred alternative in the Proposed Plan.

45

RECORD OF DECISIONBountiful/Woods Cross/Sth South PCE Plume NPL Site - Operable Unit I September 2006

PART 3: RESPONSIVENESS SUMMARY

Appendix A - Public Comment Meeting Transcript

Appendix B - Responses to Hatchco Comments

46

FIGURES

Figure 1Site Location Map

, : :. fjf^ftS&K&xji.•/^•r%:r-4-^Trri.nTTSTC,

Olle. August 20W

Figure 2

Historical Aerial Photograph1993

Bountiful, Utah

0 0015 0.03 O.OB

Miles

Source: USGS, August, 1993

Due: August 2006

Figure 3

Industrial and ResidentalAreas Proximal to Hatchco

Legend

Hatchco Property Boundary

I Study Area 3

Bountiful, Utah

Sources. Satellite Image, GlobeXplorerSeptember 21, 2003, .3048 meter resolution.City boundaries, Census 2000 data.Study Area Boundary and Hatcnco boundary, COM.

Due (Uiguit2<XW

Figure 4. Conceptual Site Model for Exposure to Groundwater

Human Receptors Ecological Receptors

Off-Site Off-Site AquaticResident Worker Receptors Wildlife

Dry Cleaner. Other

Sources (?)

Spills,

Releases

Ground

Water

V DCs

Soil Gas

Domestic Well

Groundwater dischargeat the surface

Outdoor Airi

i -

Indoor Air

i

Inhalation

Inhalation

o o

••

' VOCs

Indoor

Water

Surface

Water

Ingestion

Dermal contact

Direct contact

Ingestion

•

o

•

o o

•

o

Pathway is or might be complete, but exposure is considered to be minor; qualitative evaluation

Pathway is or might be complete and could be siqnificant; qualitative evaluation

G:\DEB\Bountiful CSM Figure 4.xls

Figure 5Hatchco Plume,

Residential and Monitoring Wells,and Warm Springs Fault

Legend

o Monitoring Wells

'-' Monitoring Wells Inside Plume

• Temporary Monitoring Wells

Background Well

• Residential Wells in 1996

• Domestic Wells

© Municipal Well

Warm Springs Fault

Hatchco Property Boundary

~^\ Hatchco Plume

Bountiful, Utah

Sou-ces Well, Plume, and Fault locationsbased on data provided by COM on 7/2005Date of image is unknown

Projection. StBte Plane Utah North, NAD 83

Date AuguR 2006

N

SCA_E: -"-230'

EGENDHATCHCO PROFiRTY BOUNDS

'''V- MON'TOR'NC WELL

8W DIRECT-PUSH GROUNDiYMEPS*MP. NG LCCATION

ISOCONCD.TWTION CONTOLRS ARE PRESENTEDL. CONTOURS AR: DASHED WHE'E INFERRED.

COVTOLrS RE3RESEN' A SUM TOT'J. OF ALLCHLORINATED E7KAM FIONS.

Figure SAIsoconcentration Contour Map of Chlorinated

Hydrocarbons in Shallow Groundwater (October 2002)

Remdial Investigation. HDR Engineering, Inc., Figure 6-12, October 2003

N

A;

SCALE: T-20C

GEOLC3IC CRCSS-SECTICN "RAVERSEFigure 5B

Geologic Cross-Section Traverse

Source: Remedial Investigation, IIDR En;ineerln«;, Inc., Jtn. 2003

-EGIN3j Approximate Hatchco Property Boundary17 Approximate Location of Former Building and Structures

N

tNot To Scale

hignre (\Historic Site Features Location Plan

Source: Remedial Investigation Report, Figure 3-1,HDR Engineering, Inc. January, 2004

Figure 7

Aerial PhotographSeptember 1, 2000

Bountiful, Utah

0 0015 0,03••=

Miles

Source Globe Explorer, 9/1/2000, 1

0,06

Date. Ajptt 2006

Figure 8Schematic Diagram

Bmmtifiil/Woods Cross 5* SouthPCE Plume

Operable Unit 2Davis County, Utah

NOT TO SCALE

Source: Remedial Investigation Report, Figure 3-1COM, July 2005

AujllatlO. J006

MW 14S MW--12S

•I38C-

o5 425C-

424C-

,-r-

.r

MW-3S MW-3D

'

y- —

-4:e: .

--4250 E

-

LEGEND NOTES

^| FILL [H:*;\ SILIY SANO/FiNE 3AMD

SAND £j SILT

INFF.RRF.O BOUNDARY

-MONITORING WEL.

SCALE 1" = 150'VERTICAL:

i^_—^-, ^ LOCATION OF GEO-.OCICCLAY n^Tj GRAVE. W/ FiNES T^ STATIC WATFR LEVFL CROSS -SFCTION.

2. STATIC WAFER•'. LNLD IN L;<V.AL COLLt GTrC OCT. 25,

20C2.

Figure 9Geologic Cross-Section A —A'

Suuice Remedial Investigation Report, Figure6-2, HDR Engineering, Inc

6J.7WH1J3IU0I7

/

•

3£*cjai«u?

i

tJ Not To Scale

LEGEND--- HATCHCO PROPERTY BOUNDARY

8 SUBSURFACE SOIL SAMPLING LOCATION

NON-DETCCTSAMPLE ID (LAST 3 DIGITSDENOTE SAHi

700 SOUTH STREETNOTES

ALL CONCENTRATIONS ARE IN mg/kg

M) ONLY ANALYTCAL RESULTS EXCEEDING DETECTIONLIMITS ARE PRESENTED.

Figure 10Subsurface Soil Sampling Results

Source: Remedial Investigation Report, Figure 6-9,HUR Engineering, Inc. January, 2003

Figure 111'CK In Vadose Zone Soils

(SA03-950 West)Bountiiiil'Woods Cross SupcrfundSite

PCE PlumeOperable Unit 2

Davis County, Utah

Legend

TCE Concentration (ug/kg)

O .09

Non-Dctects

Source: Remedial Investigation Report, Figure 4-10.COM July 2005

August 10. 2006

N

SCALE: 1"- APPROX. 35'

LEGEND:INFERREDPOTENTHL SOURCE

MB(TCE CONCENTRATIONi 60 ug/Kj)

HATCHCO PROPERTYBOUNDARY

StBSUHFACE SOLSAMPLING IQCATUN

NO'J-OfTECT

on-xt-om £W?i£ 10 (usr 3CNGITB BENOTSAMPLE

CONTOUR - 10ug/l SOIL CAS

(25' DEPTH)

NOTES: _I . AU CONCENTRATIONS ARE

IN

2. CM.* ANAOmCAl. RESULTSEXCEEOING DETEOOV LIMffSARE PRESENTED.

700 SOUTH STREETFigure 12

Inferred Potential Source Area

Source: Focused Feasibility Study, HDR Engineering. Inc.. March, 2004.

Figure 13Cross-Section A - A'

Bountiful/Woods Cross 5th Southl>Ct Hume

Operable Unit 2Davis County, Utah

LegendC-1 » ConftnlnB Unit IC-2 = Confining Unit 2C-3 -Cwiftntng Unrt 3

•U-. [Iff,, Ion,•M'-Middle Zuic"L" » LovwrZone

OUOH

90

Map crvtfed by COM

TABLES

Table 1 - PCE and Degradation Compound Results In Groundwater (OU1) - April 2005

Location

OU01-MW01O

OU01-MW01D

OU01-MW01S

OU01-MW01S

OU01-MW01S-Dup

OU01-MW02S

OU01-MW02SOU01-MW02S-Dup

OU01-MW02S-Oup

OU01-MW03S

OU01-MW03S

OU01-MW04S

OU01-MW04S

OU01-MW05S

OU01-MW06S

OU01-MW07S

OU01-MW06S

OU01-MW09S

OU01-MW10S

OU01-MW11S

OU01-MW11S

OU01-MW12S

OU01-MW13S

OU01-MW13SOU01-MW14S

OU01-MW14S

SA01-MW02D

SA01-MW02D

SA01-MW02S

SA01-MW02S

SA01-MW03SSA01-MW03S

Notes:2.7-100 -

MWO1M -

Tetrachloroethene(ug/L)

35 E330

0.11 J1U

23

26 E13D

21

24 D6.4

5.10

11

8.8 JD0.23 J0.5 U

O.SU

2.3

0.16 J0.5 U1.6

5U

O.SU

0.91

SU

O.SU

5U

7.9

10 O0.32 J10 U

0.26 J

SOU

Trtchloroethene(ug/L)

1.2_J1.2 JD

5

4.2 D

0.62

430 EMOO

290 E280 D250 E170 D510 E2800

0.17 JO.SU

0.49 J

0.18 J0.17 J

3.1

2.1

SU

1.3

61 E500

3.1

3.7 JD3ME

340 D36 E310

9.7

SOU

1 ,1 -Dlchloroethene(ug/L)

0.5 U2U

O.SU

1U

O.SU

O.SU

10 U0 5 U

20 UO.SU

SU

O.SU

20 UO.SU

O.SU

O.SU

O.SU

0.5 UO.SU

O.SU

5U

O.SU

O.SU

SU

O.SU

SU

O.SU

10 U0.75.10 UO.SU

sou

cis-1,2-Dichloroethene (ug/L)

O.SU

2U

38 E• 310

O.SU

660 E270 D540 E6400

130E

130D

470 E220 D0.32 JO.SU

0.46 J

O.SU

O S U

12

O.SU

5U

4.6

110 E98 D150E

1800

270 E310 O400 E360 D32 E44 JD

trans-1,2-Dlchloroethene (ug/L)

0.5 U2U

1.4

1.3 DO.SU

4.9

15 D4.3

20 U10

10 D2.3

20 UO.SU

O.SU

O.SU

O.SU

O.SU

1.1

O.SU

SU

0.17 J5.3

SO

1. .SU

3.1

4.2 JD .16

15 D1.7

SOU

Vinyl Chloride(ug/L)

O.SU

2U

2.6

2.4 D

O.SU

78 E46D

"S2E

960

33 E29 D56 E39 DO.SU

O.SU

O.SU

O.SU

O.SU

1.5

O.SU

SU

0.2 J6.4

8.1 D160 E1500 '.19

210

S3E

51 D7.3

SOU

Total Detected CAHs(ug/L)

36.2

34.2

47.1

38.9

23.8

1198.9494.0

907.3

940.0

429.4

344.11051.3

547.8

0.7

na102.50.3

17.7

3.7

na6.5

165.6161.1314.1313.7680.0

685.2

508.1457.051.0

44.0

Detected concentrations are highlighted in yellowConcentrations exceeding MCLs are bold-facedDilution results are presented on a separate fine and highlighted in blue.

PCE • TetrachloroetheneCAHs - Chlorinated Aliphatic Hydrocaibonsug/L - Micrograms per liter

ns -Not sampledna - Not applicable

J - Estimated

U - Not Detected

D - DilutionE - The amount detected is above the method calibration limit

B - Present in blank•When duplicate samples were collected, only maximum is reported

Tables 1 and 2 April 2005_May 2006.xls Page 1 of 1

Table 2 - PCE and Degradation Compound Results In Groundwater (OKI) - May 2006

Location

OU01-MW01D

OU01-MW01D

OU01-MW01S

OU01-MW01SOU01-MVW)1S-Dup

OU01-MW02SOU01-MW02SOU01-MVUD2S-DupOU01-MVW2S-Dup


OU01-MW04SOU01-MVW4S

OU01-MWD5S

OU01-MWD5S

OU01-MVUD7S

OU01-MW08SOU01-MWD9S

OU01-MW09S


OU01-MW11S


OU01-MW13SOU01-MW13SOU01-MW14S

OU01-MW14SSA01-MWQ2D

SA01-MW02D

SA01-MW02S

SA01-MWQ2SSA01-MWD3SSA01-MWD3S

Notes:2.7 -

1OO -MWO1M -

Tetrachloroethene(M9/L)

nsnsnsnsns

0.34 JD10 Unsnsnsns3.8

2.3 JD

ns

ns

ns

ns

1.3 JO

25 U0.5 U

05 U

2U

1.8

1.1 JD

0.92

2.5 U2U

20 U

8.5 D

6.4 JD

18 D

SOU

2.5 U

25 U

Trichloroetnene(M9/U

nsnsnsnsns

280

200

nsnsnsns

78 E

520

ns

ns

ns

ns

2JD

25 U

2.9

7.6

5.9040 E

260

45 E

32 D

110 ED

90D

240 ED

1900

420 ED

26005.6 D

25 U

1,1-Oichloroethene(M9/L)

nsnsnsnsns1U10 Unsnsnsns

0.5 U2.5 U

nsnsnsns

2.5 U25 U0.5 U

. 0.32J

2U

0.5 U

2.5 U

0.5 U

2.5 U

2U20 U

1U

10 U

1.9 JD

SOU

2.5 U

25 U

cis-1,2-Dlchloroethene (ug/L)

nsnsnsnsns

280 ED2300

nsnsnsns

82 E65 D

nsnsnsns

2.5 U25 U

14

55E

43 D •

49 E380

72E60 D

350 ED

3200220 ED

1900

1800 ED

1200034D

20 JD

trans-1,2-Dlchloroethene (ug/L)

nsnsnsnsns

13 D9.4 JO

nsnsnsns1.7

2.5 Unsnsnsns

2.5 U25 U

0.62

3.8

2.9 0

0.89

2.5 U

5.6

3.8 D

13 D

8.7 JD

4.1 D

10 U

25 D

23 JD

1.1 JD

25 U

Vinyl Chloride(H9/L)

ns

ns

ns

ns

ns

40 ED

210

nsnsnsns11

6.20

nsnsnsns

2.5 U25 U

02SJ

117.20

5.4 '2.6 D

. 2.2

25U

510

340

130

7.9 JO

1000

560

3.6 D

25 U

Total Detected CAHs<M9/L)

na

na

na

na

na

381.3

2804

na

na

na

na

176.5

124.5

na

na

na

na

3.3

na

17.8

77.7

59.0

97.1

67.7

125.7

95.8

524.0

452.7485.6

394.3

2364.91539.0

44.3

20.0

Detected concentrations are highlighted in yellowConcentrations exceeding MCLs are bold-facedDilution results are presented on a separata line and highlighted in blue.

PCE • TetrachloroetheneCAHs - Chlorinated Aliphatic Hydrocarbonsug/L • Micrograms per liter

ns - Not sampledna -Not applicable

J -EstimatedU - Not Detected

D - DilutionE - The amount detected is above the method calibration limit

B - Present in blank•When duplicate samples were collected, only maximum is reported

Tables 1 and 2 April 2005_May 2006.xls Page 1 of 1

Table 3. Groundwater Results Exceeding Primary MCLs

Station

DP25

DP26

DP27

DP28

DP29

DP31

DP32

DP33

DP34

DP35

DP36

DP37

DP38

DP39

DP40

DP41

DP42

DPG-064

DPG-082

DPG-104

Sample

02B-SA3-DP25S-GW-017


02B-SA3-DP26S-GW-0 1 702B-SA3-DP26S-GW-01702B-SA3-DP27S-GW-0 1 702B-SA3-DP27S-GW-01702B-SA3-DP28S-G W-0 1 7

02B-SA3-DP28S-G W-0 1 702B-SA3-DP28S-G W-0 1 702B-SA3-DP29S-GW-01702B-SA3-DP29S-GW-017

02B-SA3-DP29S-GW-0 1 702B-SA3-DP3 1 S-GW-0 1 7

02B-SA3-DP3 1 S-GW-0 1 702B-SA3-DP32S-GW-OI702B-SA3-DP32S-GW-01702B-SA3-DP32S-GW-01702B-SA3-DP33S-GW-01702B-SA3-DP33S-GW-OI702B-SA3-DP33S-GW-0 1 702B-SA3-DP34S-GW-01702B-SA3-DP34S-GW-0 1 702B-SA3-DP35S-GW-017

02B-SA3-DP35S-GW-01702B-SA3-DP35S-GW-01702B-SA3-DP36S-GW-01702B-SA3-DP36S-GW-01702B-SA3-DP36S-GW-01702B-SA3-DP37S-GW-01702B-SA3-DP37S-GW-OI7


02B-SA3-DP38S-GW-0 1 702B-SA3-DP38S-GW-017

02B-SA3-DP39S-GW-01702B-SA3-DP39S-GW-01702B-SA3-DP39S-GW-017

02B-SA3-DP40S-GW-0 1 702B-SA3-DP40S-GW-OI702B-SA3-DP40S-GW-0 1702B-SA3-DP4 1S-G W-0 1 702B-SA3-DP41S-GW-017

02B-SA3-DP41S-GW-01702B-SA3-DP42S-G W-0 1 702B-SA3-DP42S-GW-017

DPG-064-031

DPG-064-03 1DPG-064-031DPG-082-044DPG-082-044DPG-082-044

DPG- 104-03 5DPG-104-035

SampleDate

12/18/0212/18/0212/18/02

12/18/0212/19/02

12/19/0212/19/02

12/19/0212/19/02

12/19/0212/19/0212/19/0212/19/0212/19/02

12/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/19/0212/20/02

12/20/0212/20/02

12/20/0212/20/02

12/20/0212/20/0212/20/0212/20/0212/20/0212/20/0212/20/0212/20/02

12/20/0212/20/0212/20/02

3/21/023/21/023/21/02

3/20/023/20/023/20/023/21/02

3/21/02

Analyte

Trichloroethene

cis- 1,2-Dichloroethene

TrichloroethcneVinyl Chloride

cis- 1 ,2-DichloroethcneVinyl Chloride

cis- 1 ,2-DichIoroetheneTrichloroethcneVinyl Chloride

cis- 1 ,2-DichlorocdiencTrichloroetheneVinyl ChlorideTrichloroethene

Vinyl Chloridecis- 1 ,2-Dichloroethene

TrichloroetheneVinyl Chloride

cis- 1 ,2-DichloroetheneTrichloroetheneVinyl Chloride

cis-l,2-DichloroetheneVinyl Chloride

cis- 1 ,2-DichloroetheneTrichloroetheneVinyl Chloride

cis- 1,2-DichloroetheneTrichloroetheneVinyl Chloride

Trichloroethcne

Vinyl Chloridecis- 1 ,2-Dichloroethcne

TrichloroetheneVinyl Chloride

cis-l,2-DichloroetheneTrichloroetheneVinyl Chloride

cis- 1 ,2-DichloroetheneTrichloroethcneVinyl Chloride

cis- 1 ,2-Dichloroethcne

Trichloroethene

Vinyl Chloridecis- 1 ,2-Dichloroethene

Vinyl Chloride

cis- 1 ,2-DichloroetheneTrichloroetheneVinyl chloride

cis- 1 ,2-Dichloroethene

TrichloroetheneVinyl chloride


Maximum Contaminant Level '"(ug/L)

570527027052705252705270527027052705252705270527052

70

5 • '

270

2

705

2

70

52

5

2

Groundwater Concentration(ug/L)

5.4

1100

2029

160

23

82

2517

71

2320

5.7

3.4

120

55

24

190

92

38

290

55

490

18084

130

1409.4

17

6.7

460

14

16

370410

28

15041

30

200

8837

250

26

27391054

467

289

151

7.62

11.14.99

[1] Primary Maximum Contaminant Level

Table 3. Groundwater Results Exceeding Primary MCLs (Continued)

Station

DPG-140

DPG-207

MW03U

MW-10S

MW-11S

MW-12S

MW-13S

Sample

DPG-140-032DPG-207-036DPG-207-036

DPG-207-036

03B-SA01-MW03U-GW-00103B-SA01-MW03U-GW-002

03B-SAO 1-MW03U-GW-003

03B-SA01-MW03U-GW-004

MW-10S-04

MW-10S-03

MW-10S-01

MW-IOS-02MW-10S-03

MW-IOS-02

MW-10S-01MW-10S-04

MW-10S-03

MW-IOS-02MW-10S-04

MW-10S-01MW-11S-04

MW-11S-OI

MW-I1S-04

MW-11S-01MW-11S-04

MW-11S-02MW-I1S-01

MW-11S-03

MW-12S-03MW-I2S-04

MW-12S-01

MW-12S-02

MW-12S-04

MW-12S-03

MW-12S-02

MW-12S-OI

MW-12S-03MW-12S-01MW-I2S-04

MW-12S-02

MW-I3S-01MW-13S-04

MW-13S-03

MW-13S-02MW-13S-01

MW-13S-03

MW-13S-04

MW-13S-02

MW-13S-01MW-13S-04

MW-13S-03

MW-13S-02

SampleDate

3/20/023/20/02

3/20/02

3/20/02

3/28/036/26/03

9/24/03

12/18/03

7/23/03

4/21/03

8/19/02

1/20/03

4/21/03

1/20/03

8/19/027/23/03

4/21/03

1/20/03

7/23/03

8/19/02

7/23/03

8/19/02 .

7/23/03

8/19/027/23/03

1/20/038/19/02

4/21/03

4/21/03

7/23/0310/7/02

1/20/03

7/23/03

4/21/031/20/03

10/7/02

4/21/0310/7/027/23/03

1/20/03

10/7/027/23/03

4/21/03

1/20/0310/7/02

4/21/03

7/23/03

1/20/03

10/7/02

7/23/03

4/21/031/20/03

Analyte

Trichloroethene


Trichloroethene

.Vinyl chloride

Methyl tert-Butyl EtherMethyl tert-Butyl Ether

Methyl tert-Butyl Ether

Methyl tert-Butyl Ether



cis-l,2-Dichloroethene

cis- 1,2-DichIoroetheneTrichloroethene

Trichloroethene

Trichloroethene. Trichloroethene

Vinyl chlorideVinyl chloride

Vinyl chloride

Vinyl chloride



Trichloroethene



Vinyl chloride

cis- 1 ,2-Dichloroethenecis- 1 ,2-Dichloroethene

cis-l,2-Dichloroethenecis- 1 ,2-Dichloroethene

Trichloroethene

Trichloroethene

Trichloroethene

Trichloroethene


Vinyl chloride

Vinyl chloride



cis- 1 ,2-DichloroetheneTrichloroethene

Trichloroethene

Trichloroethene


Vinyl chloride


Maximum Contaminant Level '"(HE/L)

57052

NANANANA707070705555222270705522227070707055552222

7070707055552222

Concentration in Groundwater

(Mg/L)39.4

4811346

92.32400

3000

2500

13000260292283310123 '

10794.6160

41.1

61.2

31.3

60.2

14087.4

27.4

1754.315.3

61.1

9.32

75199113149

99.7

34.2

65.2

40.412.731

31.1

3912213114114143.9

6213085.1

22.3

20.5

22.229.6

[1] Primary Maximum Contaminant Level

NA = MCL not available for this chemical

Table 3. Groundwater Results Exceeding Primary MCLs (Continued)

Station

MW-US

MW-1S

MW2D

MW2S

MW-3D

MW-3S

MW-4S

MW-9S

WPH01

WPH10

Sample

MW-14S-03

MW-14S-02MW-I4S-01

MW-14S-04

MW-14S-03

MW-14S-02MW-14S-01

MW-14S-04

MW-I4S-03

MW-14S-02MW-14S-04

MW-14S-OI

MW-IS-04

01B-BWX-MW-09-I213

OIB-BWX-MW-09-1213

01B-BWX-MW- 10-12 1301B-BWX-MW-10-1213

OlB-BWX-MW-10-1213

MW-2S-03MW-2S-02

MW-2S-01MW-2S-04

MW-2S-02

MW-2S-03MW-2S-OI

MW-2S-04

MW-2S-03MW-2S-01

MW-2S-04

MW-2S-02MW-3D-04

MW-3S-04

MW-3S-02

• MW-3S-03MW-3S-01MW-3S-01

MW-3S-04

MW-3S-03MW-3S-02MW-3S-01

MW-3S-04

MW-3S-02MW-3S-03MW-4S-01

MW-4S-02

MW-4S-02MW-4S-01

MW-4S-04

MW-9S-03MW-9S-04

02B-WPH01-GW-OOI

02B-WPH01-GW-00102B-WPH10-GW-001

02B-WPH10-GW-OOI

02B-WPH10-GW-OOI

SampleDate

4/23/03

1/21/03

10/7/02

7/24/03

4/23/03

1/21/03

10/7/02

7/24/03

4/23/03

1/21/03

7/24/03

10/7/02

7/23/03

12/13/01

12/13/01

12/13/01

12/13/01

12/13/01

4/23/03

1/21/03

10/25/02

7/24/031/21/03

4/23/03

10/25/02

7/24/03

4/23/03

10/25/027/24/03

1/21/03

7/24/03

7/24/031/21/03

4/23/03

4/24/02

4/24/02

7/24/03

4/23/031/21/034/24/02

7/24/03

1/21/034/23/03

4/24/02

1/21/03

1/21/034/24/02

7/24/03

4/21/037/23/03

6/21/02

6/21/02

7/15/027/15/02

7/15/02

Analyte




cis- 1 ,2-Dichloroethcne

Trichloroethene

Trichloroethene

Trichloroethene

Trichloroethene

Vinyl chloride


Vinyl chloride

Trichloroethene


Trichtoroethenecis- 1 ,2-Dicbloroediene

Trichloroethene

Vinyl Chloride

cis- 1 ,2-Dichloroethenecis- 1 ,2-Dichloroethene



Trichloroethene

Trichloroethene

Trichloroethene

Trichloroethene

Vinyl chloride

Vinyl chloride

Vinyl chloride

Vinyl chloride

Trichloroethene


cis- 1 ,2-Dichlorocthene


Trichloroethene

Trichloroethene

TrichloroetheneTrichloroelheneVinyl chloride

Vinyl chloride


Trichloroethene

TrichloroetheneVinyl chlorideVinyl chloride

Vinyl chloride

TrichloroetheneTrichloroethene

Trichloroethene

Vinyl Chloride


Trichloroethene

Vinyl Chloride

Maximum Contaminant Level "'(Mg/L)

70

7070

70

5

5

5

5

2

22

2

5

70

5

70

5

2

70

7070

70

5

5

55

2

22

?5

7070

7070

5

5

5S22

225

5

22

2

55

5

2

70

5

2

Groundwater Concentration(ug/L)

643

1323

662

596

5651021

507

551

156

297

88.6

98.3

6.39

200

280

400

58

52

165

223352

403129

95.8

206

27424.7

• 63.6

79.1

70.88.8

733946

865405207

445

48063972.4

108

277150

8.48

5.972.9

2.31

2.215.09

5.3

13.3

5.4

353.362.7

224.1

[ 1 ] Primary Maximum Contaminant Level

Table 4VOCs Detected in Subsurface Soils (ug/kg) (EPA Method 8260B)

1,2,4-Trimethylbenzene1,3,5-Trimethylbenzene4-Isopropyltoluenecis-1,2-DichloroetheneEthylbenzeneIsopropylbenzenem- and p-XyleneNaphthalenen-Propylbenzeneo-Xylenesec-Butylbenzenetert-ButylbenzeneTetrachloroetheneTolueneTrichloroetheneVinyl chloride

DPS-041-013

21-Mar-02

U

uU

3.66 JUUuuuuuuuu

1.64 JU

DPS-064-020

21-Mar-02

U

74,71339,014

U30,57489,83335,808

U67,7687,252 J161,83213,017

U1,890 J2,834 J

U

DPS-064-035

22-Mar-02

U

UU

33.4UUuuuuuuuu

20.93.32 J

DPS-082-016

20-Mar-02

U

Uu

u563

2,305U

8,25917,965

U11,471

UUUuu

DPS-082-020

20-Mar-02

583

UU

46,241UU

5634,639

UUUu

930U

90,956U

DPS-104-016

21-Mar-02

53.9 J

UU

U51J

Uu

36.5 J53 J

UUUuuuu

DPS-207-009

20-Mar-02

33,602

15,3433,717

9,2369,7734,219

32,450533644,71916,877

UU

18,7214,32622,292

U

DPS-207-020

20-Mar-02

U

Uu

uuuu

567 JUuuuuuuu

DPS-207-098*

20-Mar-02

3,544 J

U317 J

U369 J387 J367 J

3,821 J451J342 J

UUUuuu

* Duplicate of Sample DPS-207-020U - UndetectedJ - Result is an estimated quantityME - None Established

W.S. Hatch CoRemedial Investigation Final ReportTable 6-7

Table 5

Evidence of Biodegradation of Chlorinated Organics

Well I.D.

Analyte

Oxygen (mg/L)

Nitrate (mg/L)Iron (H) (mg/L)Sulfate (mg/L)

Sulfide (mg/L)

Methane (mg/L)Oxidation reductionpotential (mV)pH

IOC (mg/L)

Temperature (mg/L)

Carbon dioxide (mg/L)

Alkalinity (mg/L)

Chloride (mg/L)

Hydrogen (nM)Volatile Fatty Acids(mg/L)BTEX (mg/L)Fetrachloroethene(mg/L)Trichloroethene (mg/L)

Dichloroethene (mg/L)

Vinyl Chloride (mg/L)

Ethene/Ethane (mg/L)1,1,1 -Trichloroethane(mg/L)

Dichloroethane (mg/L)Chloroethane (mg/L)

Carbontetrachloride

Chloroform (mg/L)

Dichloromethane (mg/L)

Total Points:

MW-2S

Concentration

0.83

2.45ND57.5

.ND0.093

255.3

6.84

0.533

14.53454.88*

389*

349**

*

0.00083

0.0147

0.2060.00137 (1,1-DCE)0.352 (cis-l,2-DCE)0.00939 (trans- 1,2-

DCE)0.097

ND

0.00209

0.0133 (1,1-DCA)

ND

ND«

*

PointsAwarded

0

000

0

0

0

0000*0*

0*

0*

0*

0

0

0

2

20

0

20

00*

0*

6

MW-3S

Concentration

1.84

1.18ND119

NDND

220.6

6.67

0.569

14.89499.57*

382*

222*+

*

0.00464

0.00667

0.2070.00054 (1,1-DCE)0.405 (cis-l,2-DCE)0.0279 (trans- 1,2-

DCE)0.0724

ND

ND

0.0065 (1,1-DCA)

ND

ND**

PointsAwarded

0

000

00

0

00

00*0*0*

0*

0*

0

0

0

2

20

0

00

00*

0*

4

MW-10S

Concentration

3.53

0.0990.7235

ND

ND

81.9

6.580.542

15.14

580.76*

413*346*

*

*

.00179

0.00244

0.09460.00066 (1,1-DCE)0.283 (cis- 1,2-DCE)0.0044 (trans-1, 2-

DCE)0.0602

ND

ND

0.00899 (1,1 -DC A)

ND

ND**

PointsAwarded

0200

00

0

000

0*0*

0*

0*

0*

0

. 0

0

2

20

0

0

0

00*

0*

6All. concentrations are results of 2002 sampling events.ND = Not Detected

*Not sampled or insufficient information to assign score resulting in an automatic zero.

W.S. Hatch Co.Remedial Investigation ReportTable 7-5

Table 6 Maximum PCE7TCE Degradation Compound Results in Domestic Wells

Location*

DWD1

DWD2

DW03

DW04

DW05

OWD6

DWD7

OWQ8

OW09

DW10

DW11

DW12

DW13

DW14

DW14

OW15

DW16

DW16

DW17

DW18

DW19

OW20

OW21

DW22

: DW22

DW23

OW24

DW2S

. DW25

DW26

Tetrachloroethene (ug/L)

Round 1March 2003

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

ns

na

ns

ns

ns

ns

ns

ns

na

ns

ns

ns

na

ns

Round 2June 2003

0.20 J

0.50 U

0.31J

0.50 U

29

0.50 U

0.50 U

0.64

0.20 J

1.1

3.2

6

3.3

8.3

na

0.17 J

2.4

na

10

3.8

3.7

2.1

2.5

0.50 U

na

0.93

0.50 U

ns

na

ns

Round 3Sept 2003

ns

ns

ns

ns

0.036J

ns

ns

ns

ns

1.3 B

3.7 B

22B

3.7

33 E

na

ns

46 E

na

9.8 B

4.3 B

3.9 B

3.1 B

3.7 B

ns

na

ns

ns

ns

na

ns

Round 4Dec 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

1.6

4.8

24

2.6

37 E

22D

ns

7.9

na

ns

3.7

ns

2.4

ns

ns

na

ns

ns

43 E

280

4.4

Round 5April 2005

0.59

0.5 U

0.67

0.5 U

6

0.5 U

0.5 U

0.45 J

0.17 J

1

ns

18

4.6

ns

ns

0.26 J

43 E

38D

8.6

4.6

4.8

2.9

ns

ns

na

ns

0.5 U

16

na

ns

Round 6May 2006

0.8

ns

ns

ns

7.S

0.5 U

ns

0.16 J

0.14J

ns

ns

17

ns

ns

ns

ns

ns

ns

ns

ns

4.6

3.9

4.6

37 E

300

ns

0.5 U

45E

360

ns

Trichloroethene (ug/L)

Round 1March 2003

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

ns

na

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

Round 2June 2003

0.50 U

050U

0.50 U

0.50 U

0.17 J

050U

0.50 U

.0.30J

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

na

0.50 U

050U

na

0.56

0.50 U

0.41J

0.30 J

.0.39 J

0.50 U

0.50 U

0.50 U

ns

na

ns

Round 3Sept 2003

ns

ns

ns

ns

0.14 J

ns

ns

ns

ns

0.044 J

0.13 J

0.12J

0.13 J

0.26 J

na

ns

1.6

na

0.74

0.044 J

0.57 B

0.50 JB

0.53 B

ns

ns

ns

ns

na

ns

Round 4Dec 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

0.50 U

0.50 U

0.50 U

0.50U

0.23 J

1.0U

ns

0.39 J

na

ns

0.50 U

ns

0.26 J

ns

ns

ns

ns

2

1.6JD

0.5

Round 6April 2005

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.38 J

0.5 U

0.5 U

ns

0.5 U

0.5 U

ns

ns

0.5 U

1.2

1.2 JD

0.58

0.5 U

0.43 J

0.53

ns

ns

ns

0.5 U

. 0.75

ns

ns

Round 6May 2006

0.16 D

ns

ns

ns

05 U

0.5 U

ns

0.28 J

0.5 U

ns

ns

0.5 U

ns

ns

ns

ns

ns

ns

ns

ns

0.46 J

0.64

• 0.72

2.8

2.50

ns

0.5 U

2

1.8 J_0

ns

Notes: PCE -Tetrachloroetheneug/L -Micrognuns per liter

s nit highlighted io yellow

Concentrations exceeding MCLs arc bold-faced

ns -Not sampled

na -Not applicable

'When duplicate samples were collected, only maximum is reported

DW14 Dilution results are presented on a separate line and highlighted in blue.

J-Estimated

U -Not Detected

D-Dilution

E -The amount detected is above the method calibration limit

B -Present in blank

Table 6 Maximum PCE/TCE Degradation Compound Results in Domestic Wells (Continued)

Location*

DW01

DW02

DW03

DWD4

DW05

DW06

DW07

DWOB

DW09

OW10

DW11

DW12

DW13

DW14

DW14

DW15

DW16

DW16

DW17

DW18

DW19

DW20

DW21

DW22

DW23

DW24

DW25

•• • .DW2S

OW26

Round 1March 200}

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

ns

na

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

Round 2June 2003

0.50 U

0.50 U

0.60 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

na

0.50 U

0.50 U

na

0.50 U

0.50 U

3.3

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

ns

na

ns

1,1-Dichloroethene (ug/L)

Round}Sept 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

0.50 U

0.50 U

0.50 U

0.50 U

050U

na

ns

0.50 U

na

0.50 U

0.50 U

5.5

050U

1

ns

ns

ns

ns

na

ns

Round 4Dec 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

1.0 U

ns

0.50 U

na

ns

0.50 U

ns

0.50 U

ns

ns

ns

ns

0.50 U

2.0 U

0.50 U

Round 5April 2005

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

05 U

0.5 U

0.5 U

0.5 U

ns

0.5 U

0.5 U

ns

ns

0.5 U

0.5 U

2U

0.5 U

0.5 U

3.1

0.5 U

ns

ns

ns

0.5 U

0.5 U

ns

ns

Round 6May 2006

1.3

ns

ns

ns

0.5 U

0.5 U

ns

0.5 U

0.5 U

ns

ns

0.5 U

ns

ns

ns

ns

ns

ns

ns

ns

3.3

0.37 J

0.58

2U

ns

0.5 U

05 U

2.5 U

ns

Round 1March 2003

. ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

ns

na

ns

ns

ns

ns

ns

ns

ns

ns

ns

na

ns

Round 2June 2003

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

na

0.50 U

0.50 U

na

0.50 U

0.50 U

0.20 J

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

ns

na

ns

cis-1,2-Dichloroethene (ug/L)

Round]Sept 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

0.50 U

0.50 U

0.50 U

0.50 U

0.50 U

na

ns

0.066 J

na

0.057 J ,

0.50 U

0.50 JB

0.50 JB

0.50 JB

ns

ns

ns

ns

na

ns

Round 4Dec 2003

ns

ns

ns

ns

0.50 U

ns

ns

ns

ns

0.50 U

0.50 U

0.50 U

0.50 U.

0.50 U

1.0 U

ns

0.50 U

na

ns

0.50 U

ns

0.50 U

ns

ns

ns

ns

0.50 U

2.0 U

0.50 U

Round 5April 2005

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

0.5 U

ns

0.5 U

0.5 U

ns

ns

0.5 U

0.5 U

2U

0.5 U

0.5 U

0.5 U

0.5 U

ns

ns

ns

0.5 U

0.5 U

ns

ns

Round 6May 2006

0.5 U

ns

ns

ns

0.5 U

0.5 U

ns

0.5 U

0.5 U

ns

ns

0.5 U

ns

ns

ns

ns

ns

ns

ns

ns

0.5 U

0.5 U

0.5 U

2U

ns

0.5 U

0.5 U

2.5 U

ns

Notes: PCE -Tetrachlo'roetheneug/L -Micrograras per lilcr

2.7 *| Detected concentrations arc highlighted in yellow-H3100-1 Concentrations exceeding MCLj arc bold-faced

DS -Not sampled

na -Not applicable

•VWien duplicate samples were collected, only maximum Is reported

; Dilution results are presented on a separate line and highlighted in blue.

J -Estimated

U -Not Detected

D -Dilution

E -The amount detected Is above the method calibration limit

B -Present In blank

Table 7. Chemicals of Human Health Concern at Operable Unit 1

Receptor Chemicals of Concern

Current/FutureResidents or Workers

Methyl tert-butyl ether (MTBE)

Terrachloroethene (PCE)

Trichloroethene (TCE)

Vinyl Chloride

COC in groundwater that result in a cancer risk above 1E-04 or a noncancer HQ(MTBE only) above 1

Table 8. Summary Statistics and Exposure Point Concentrations of GroundwaterChemicals of Concern

Station

DP28

DP29

DP30

DP31

DP32

DP33

DP34

DP35

DP36

DP37

DP38

DP39

DP40

Analyte

Methyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl ether

TetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl Chloride .Methyl tert-butyl etherTctrachloroetheneTrichloroethene.Vinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl Chloride

Methyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTctrachloroethcne

Trichloroethene

Vinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl ether

TetrachloroetheneTrichloroetheneVinyl Chloride

DetectionFrequency

0/1

0/11/11/11/10/11/11/10/1

l/lI / I1/10/11/11/11/10/1

0/11/10/10/11/11/11/10/11/11/1I/I0/11/11/1

• 1/11/10/11/11/10/11/11/1I/I0/11/11/11/10/11/11/11/10/10/11/11/10/10/11/11/11/1I / I1/11/1

Concentration (ug/L)

Minimum

0.25

0.25202997

0.252.2

230.250.182517

0.250.772320

0.250.250.150.250.250.875.73.4

0.250.765524

0.254923829

0.254.555

0.252.6

180

84

0.252.61409.4

0.251.5176.7

0.250.25

1416

0.250.2541028

3.81.441

30

Maximum

0.250.25202997

0.252.223

0.250.182517

0.250.772320

0.250.250.150.250.250.875.73.4

0.250.765524

. 0.254

9238

290.254.555

0.252.6

180

84

0.252.61409.4

0.251.517

6.70.250.25

1416

0.250.2541028

3.81.44130

Exposure PointConcentration

0.250.25202997

0.252.223

0.250.182517

0.250.772320

0.250.250.150.250.250.875.73.4

0.250.765524

0.254

923829

0.254.555

0.252.6

18084

0.252.61409.4

0.251.5176.70.250.25

1416

0.250.2541028

3.81.44130

Table 8. Summary Statistics and Exposure Point Concentrations of GroundwaterChemicals of Concern (Continued)

Station

DP42

DPG-064

DPG-082

DPG-104

DPG-140

DPG-207

DW15

DWI6

DW17

DW18

DW20

DW21

DW25

Analyte

Methyl tert-butyl etherTctrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl Chloride

DetectionFrequency

0/11/11/11/10/10/1

1/11/1

. 0/11/11/11/10/11/11/11/10/11/11/11/10/1l/l1/1I / I0/1I/I1/11/10/11/11/11/10/12/20/20/20/36/64/60/60/23/32/30/30/34/4

1/4

0/4

0/33/33/3

0/3

0/22/22/20/20/1I / I1/10/1


Minimum

0.252.88837

0.250.251.926

. 15.430.951.23

15.361,054467

12.361517.62

10.2811.14.99. 10.939.41.36

113.91,34692.30.250.170.250.250.252.4

0.25

0.250.257.4

0.560.250.252.9

0.040250.252.10.260.250.252.5

0.390.250.25282

0.25

Maximum

0.252.88837

0.250.251.9261

5.430.951.23

15.361,054467

12.361517.62

10.2811.14.99

10.939.4106

113.91.34692.30.2510.50.50.50.2559.81.6

0.5

0.2510

0.740.50.254.30.50.5

0.253.10.50.250.253.7

0.530.250.25282

0.25


0.252.88837

0.250.2519261

5.430.951.23

15.361,054467

12.361517.62

1

0.2811. 14.99

10.939.41.36

113.91,34692.30.2510.50.380.380.2559.81.6

0.380.25

100.740.330.254.30.040.310.253.10.5

0.250.253.7 .

0.530.25

0.25282

0.25


Station

MW-10S

MW-11S

MW-12S

MW-13S

MW-14S

MW-1D

MW-1S

MW2D

MW2S

MW-2S

•MW-3D

MW-3S

MW-4S

Analyte

Methyl lert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTctrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-buryl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl ten-butyl etherTetrachloroetheneTrichloroetheneVinyl ChlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl ten-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chloride

DetectionFrequency

4/43/4

1/40/4

0/44/4

4/44/4

4/40/4

4/44/40/4

4/4

4/44/4

0/44/44/44/41/4

1/4

4/44/40/44/4

4/4

0/40/44/44/4

0/4

1/1I / I1/11/1

0/11/1I/I

1/10/44/4

4/4

4/4

0/44/4

4/4

0/40/44/44/44/4

1/4

1/4

4/4

3/3


Minimum

2,4000.110.110.25

12.4494.631.3401

1

3.029.32

11.5134.212.7

1

1.3643.920.50.920.5250788.6

1

11.11.211

30.11.32

1

0.88

2802

0.250.758

52

112.195.824.7

12.132.44

1

16.67207

72.41

0.274.292.21

Maximum

13,0001.3

0.250.25

14.34160

61.2461

1

27.461.1

13.7199.7391

2.4

13029.6

11

1,021297

1

14.21.67

11

78.66.39

1

0.88

2802

0.250.758

52

116.8274

79.11

21.78.8

11

15.4639277

4.181

8.482.9


13,0001.3

0.110.25

14.34160

61.2461

1

27.461.1

13.7199.7391

2.413029.60.920.521,021297

1

14.21.67

11

78.66.39

I

0.88

280

2

0.250.7

58

521

16.8274

79.11

21.78.8

11

15.4639

277

4.180.278.482.9


Station

MW-8S

MW-9S

WPH01

WPH08

WPH10

Analyte

Methyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideMethyl tert-Butyl EtherTetrachloroetheneTrichloroetheneVinyl chlorideTetrachloroetheneTrichloroetheneVinyl ChlorideTetrachloroetheneTrichloroetheneVinyl ChlorideTetrachloroetheneTrichloroetheneVinyl Chloride

DetectionFrequency

0/43/43/40/40/44/44/43/40/11/11/10/10/10/11/11/1I / I


Minimum

11

0.650.5

11.48

' 2.040.490.513.35.40.50.50.51.1

62.7224.1

Maximum

12.19' 1

11

3.785.31.110.513.35.40.50.50.51.1

62.7224.1


111

0.881

3.785.3

10.513.35.40.50.50.51.1

62.7224.1

Table 9. Exposure Parameters Used in the Risk Assessments for OU1

Scenario

Digestion ofGroundwater

In halation ofIndoor Air

Variable

Ingestion rate - child

Ingestion rate - adult

Body weight -child

Body weight - adult

Exposure frequency

Exposure duration - child

Exposure duration - adult

Averaging Time (noncancer)

Averaging Time (cancer)

HIF(noneaneer)

HIF(cancer)

Inhalation rate (indoors) • adult

Inhalation rate (indoors) - child

Body weight - child

Body weight - adult

Exposure frequency

Exposure duration - child

Exposure duration - adult

Averaging Time (noncancer)

Averaging Time (cancer)

HIF(noncancer)

HIF(cancer)

Units

UdL/d

kgkg

days/yryrsyrsyr»yrs

L/kg-dlAg*m'/day

mVday

kg

kgdays/yr

yrsyrsyrsyrs

m3/kg-d

m3/kg-d

Current/Future On-Site Worker

SRC 2004

CTE

-

0.7

70

219-

5-

-

6.00E-03

4.29E-04

10

--

70

219-

5570

8.57E-02

6.I2E-03

Source

-

PI-

tui[2)-

[2]-

-

MlMl[81--

[1.2][2]-

[21[2]

[2]

WMl

RME

-

1.0-

70

250-

25-

-9.78E-03

3.49E-03

20-

•-

70

250-

25

25

70I.96E-OI

6.99E-02

Source-

[1]-

[1,2]

[1,2)-

[2]

-

[4]

Ml[I.2J--

[1.2]

[1,2]-

[2][2]

[2)|4||4|

HDR2003

CTE----------_

8--

70

219-

5

5

70

6.S6E-02

4.90E-03

Source

-

--

-

--

--

---

[9]--

[1.2]

[2]-

[2]

[2|

[2]

MlHI

RME

-

--

-

--

--

---

10.4

--

70

250-

25

25

701.02E-01

3.63 E-02

Source

-

--

-

--

--

--_

[']--

[1.2]

[1.2]-

[2]

[2][2]

[41

Ml

Curreal/Fulure ResidentSRC 2004

CTE

07

1.4

IS

70

234

2

7

9

70

1.66E-02

2.I4E-03

13

7.7

15

70

234

2

7

9

701.66E-OI

2.13E-02

Source[6]

[2][1,2][1.2]

[2]

[2][2]

[21

[21

MlMl

[5]

[5]

[1,21[1,21

121[2]

[21

[2]

[21MlMl

RME1

2

15

70

3506

24

30

70

3.47E-02

1.49E-0220

15.415

70

3506

24

30

70

4.I6E-OI

1.78E-01

Source

[61

[2][1,2]

[1.2]

[1.2]

[2]

[2]

[2]

[21

Ml

Ml[1.2][5.7]

[1,2][1,2]

[1.2]

[2]

[2]

[2][2]

Ml

Ml

HDR 2003

CTE-

--

-

• --

--

--_

13--

70

350-

9

9

70I.78E-01

2.29E-02

Source-

--

-

--

--

--_

[5]--

[1,2]

[1.2]-

[2]

[2]

MlMl

RME.-

--

-

--

--

--_

20--

70

350-

3030

702.74E-01

I.17E-01

Source

-

--

-

--

--

--

• _

[1,21--

[1,2]

.[1,2]-

[21

[2]

MlMl

In accordance with USEPA guidelines, averaging time for cancer ** 25,550 days (365 days * 70 yrs). For noncanccr, averaging time = exposure duration (yrs) * 365 days.HDR 2003. Remedial Investigation for W.S. Hatdi Co. (Section 8.0 - Baseline Risk Assessment)SRC 2004. Baseline Risk Assessment for the Bountiful/Woods Crass OU2 SiteCTE = Centra] Tendency ExposureRME D Reasonable Maximum ExposureHIF = Human Intake Factor- Not evaluated

[I] U.S. Environmental Protection Agency. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. OSWER Directive 9285.6-03. March.

[2) U.S. Environmental Protection Agency. 1993. Supcrfund's Standard Default Exposure Factors for the Central Tendency and Reasonable Maximum Exposure. [DRAFT). November 4. 1993

(3) Professional judgment; Intake by worker assumed to be 1/2 that of resident.

|4| Calculated value.[5] U.S. Environmental Protection Agency 1997. Exposure Factors Handbook. Breathing rates for residents are based on the means for long-term exposure (EFH Table 5-23, USEPA 1997). The value for adults is the average of themeans for males and for females; the value for children is the avenge of the means for children ages 1-2 and 3-5.[6\ Professional judgment; Child resident intake assumed to be 1/2 that of aduh resident[7] Professional judgment; RME inhalation assumed to be 2 times the CTE value

[8] Professional judgement; CTE inhalation assumed to be 1/2 of the RME value

19) U.S. Environmental Protection Agency. 1997. Exposures Factors Handbook Average inhalation rate for tight (1.0 mVhr) and moderate (1.6 mMir) activity levels during short-term exposure periods (8 hr/day).

Note: differences in exposure parameters used by SRC 2005 and HDR 2003 are primarily due to differences in the receptors evaluated by each assessment. For example. SRC 2005 evaluated inhalation exposures to a lifetime resident (exposure as both a child and adult), whereas HDR 2003evaluated inhalation exposure to an adult resident. Differences in worker inhalation rates are due to the different EPA sources used to obtain values for this parameter.

Table 10. Cancer Toxicity Data

CHEMICAL

Methyl (en-Butyl EcherTetrachloroetheneTrichloroethene (old)Trichloroethene (provisional)Trichloroethene (provisional)Vinyl Chloride residentVinyl Chloride worker

CAS

16340441271847901679016790167501475014

INGESTIONSRC 2004

Oral SF(mg/kg-day)-l

4.0E-035.4E-011.1E-024.0E-014.0E-011.4E+007.2E-01

Source

0(2]0[2]1[W]E[4]E[4]

II

Dale

June 2004June 2004June 2004June 2004June 2004June 2004June 2004

HDR 2003

Oral SF(mg/kg-day)-l

NA5.4E-021.1E-02

NA4.0E-01

NA7.2E-01

Source

NA0[3]1[W]NA

E[3]NA

1

Date

NAOctober 2003October 2003

NAOctober 2003

NAOctober 2003

INHALATIONSRC 2004

Inhalation SF(mg/kg-day)-l

-2.0E-026.0E-032.8E-034.0E-013.0E-02I.5E-02

Source

-0[2]I[W]

E 14, 1]E[4,5]

I1

Dale

June 2004June 2004June 2004June 2004June 2004June 2004June 2004

HDR 2003

Inhalation SF(mg/kg-day)-l

NA2.0E-026.0E-03

NA4.0E-01

NA1.5E-02

Source

NA0[3]

Date

NAOctober 2003

I [W] October 2003NA

E[3]NA

I

NAOctober 2003

NAOctober 2003

SF = Slope FactorI = IRISE = EPA Provisional ValueW = Withdrawn from IRIS or HEASTO = OtherNA = evaluated by risk assessment— Toxicity value not available or chemicalHDR 2003. Remedial Investigation for W.S. Hatch Co. (Section 8.0 - Baseline Risk Assessment)SRC 2004. Baseline Risk Assessment for the Bountiful/Woods Cross OU2 Site

[I] Based on the maximum value from the range of unit risks[2] as cited in USEPA Region III Tables (4/14/04 update)[3] as cited in USEPA Region III Tables (10/9/02 update)[4] Based on EPA's TCE report (2001)[5] Oral SF used as inhalation SF

Note: differences in chemical toxicity values between SRC 2005 and HDR 2003 are due to updates in toxicity values that occurred after the completion of the HDR 2003 report.

Table 11. Summary of Total Cancer Risks to Current/FutureResidents and Workers

from Ingestion of Groundwater

STATION

DP26DP27DP28DP29DP32DP33DP34DP35DP36DP37DP38DP39DP40DP41DP42

MW03UMW2SWPH01WPH10

DPG-064DPG-082DPG-104DPG-140DPG-207MW-10SMW-11SMW-12SMW-13SMW-14SMW-1SMW-2SMW-3SMW2D

AQUIFERZONE

UuUuuuuuuuuuuuuuuuuuuuuuuuuu .uuuu

NA

CANCER RISK RANGEFOR RESIDENTS

CTEmin | - max

9E-057E-055E-056E-057E-051E-04

2E-043E-043E-052E-055E-059E-059E-051E-04

8E-051E-04

2E-042E-057E-04(£-033E-052E-056E-063E-042E-042E-041E-049E-OS9E-04

9E-053E-049£-04

2E-05

---------

1E-047E-OS7E-058E-051E-042E-042E-044E-042E-04

- | 4E-05- j 6E-05--------------

4E-041E-04

2E-048E-051E-04

2E-043E-057E-042E-032E-043E-054E-05

1E-033E-04

-! 2E-04- 2E-04

2E-04- 2E-03- 1E-04- 5E-04- 1E-03

- 3E-04

RMEmin | - max

6E-045E-044E-044E-045E-048E-041E-032E-032E-042E-043E-047E-046E-048E-045E-048E-041E-031E-045E-03IE-022E-041E-04

4E-052E-031E-031E-039E-047E-046E-037E-042E-036E-032E-04

-----------------------.----------

7E-04SE-04SE-046E-048E-041E-031E-033E-031E-033E-044E-043E-039E-041E-036E-048E-041E-032E-04SE-032E-021E-032E-043E-04IE-022E-031E-031E-OJ1E-03IE-027E-043E-03IE-022E-03

CANCER RISK RANGEFOR WORKERS

CTEmm

9E-067E-065E-066E-068E-06IE-OS2E-053E-05

4E-063E-065E-06IE-OSIE-OSIE-OS8E-062E-052E-052E-067E-052E-044E-062E-069E-07

4E-052E-052E-05IE-OSIE-OSIE-042E-053E-059E-05

4E-06

----------------------------------

maxIE-OS8E-06IE-OSIE-OS2E-053E-052E-056E-053E-05

|_ 5E-067E-068E-052E-053E-058E-062E-053E-054E-068E-053E-043E-054E-067E-063E-045E-052E-053E-053E-053E-042E-058E-OS2E-045E-05

RMEmin - 1 max

7E-OS6E-054E-055E-056E-05IE-04IE-04

2E-043E-052E-054E-059E-058E-05IE-047E-05215-04IE-042E-OS6E-041E-033E-OSIE-OS7E-063E-042E-042E-04IE-048E-058E-042E-042E-048E-043E-05

-----------------------------.---

IE-04

6E-058E-058E-05IE-042E-04IE-04

5E-042E-044E-056E-056E-04IE-042E-047E-052E-042E-043E-057E-043E-032E-043E-056E-052E-034E-042E-042E-043E-042E-032E-04SE-042E-034E-04

Aquifer Zone: "U" = Upper, "M" = Middle, "L" = Lower, "NA" = information not available on aquiferzone/sample depth

CTE = Central Tendency ExposureRME = Reasonable Maximum ExposureShading/boldface denotes cancer risk exceeding IE-04 (upper end of USEPA's target cancer risk range).


from Inhalation of VOCs Released to Indoor Airfrom Groundwater by Vapor Intrusion

STATION

DP39

DPG-064

DPG-207

MW-14S

MW-3S

MW-3D

AQUIFER

ZONE

UuUuu

NA

CANCER RISK RANGE

FOR RESIDENTS

CTEmm

5E-07

5E-06

1E-06

4E-06

3E-06

3E-06

- 1 max

------

2E-05

6E-05

7E-05

6E-05

4E-05

3E-05

RMEmm

4E-06

4E-05

IE-OS

3E-05

3E-05

3E-05

- j max

------

2E-Q4

5E-04

6E-04

5E-04

3E-04

3E-04

CANCER RISK RANGE

FOR WORKERS

CTEmm

7E-09

6E-08

2E-08

5E-08

4E-08

4E-08

-------

maxSE-07

1E-06

1E-06

1E-06

8E-07

7E-07

RMEmm

8E-08

7E-07

2E-07

5E-07

4E-07

4E-07

-I max

-----

-

6E-06

IE-OS

2E-05

IE-OS

9E-06

9E-06


CTE = Central Tendency ExposureRME = Reasonable Maximum ExposureShading/boldface denotes cancer risk exceeding 1E-04 (upper end of USEPA's target cancer risk range).


from Inhalation of VOCs Released to Indoor Airduring Indoor use of Groundwater

STATION

DP25DP26DP28DP29DP31DP32DP33DP34DP35DP36DP37DP38DP39DP40DP41

MW2SUTC02WPHOIWPH10

DPG-064DPG-082DPG-104DPG-140DPG-207MW-10SMW-HSMW-12SMW-13SMW-14SMW-1SMW-2SMW-3SMW-4SMW-9SMW2DMW-3DMW01M

AQUIFERZONE

UuUuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

NANAM


CTEmin

8E-07IE-OS

7E-068E-062E-06IE-OS2E-052E-053E-058E-064E-066E-062E-05IE-OS2E-05

2E-05

2E-05

3E-06

7E-052E-049E-064E-063E-067E-053E-052E-052E-05

2E-05

1E-042E-05

4E-05

1E-043E-06

3E-06IE-OS7E-06

-------------------------

max2E-051E-04

1E-041E-04

3E-052E-044E-044E-OS

8E-04fiE-048E-05

7E-05

2E-032E-044E-043E-042E-05

6E-053E-045E-036E-045E-052E-046E-03

- 7E-04-| 1E-04

4E-04

- 6E-04

- 4E-03

-----

5E-05

1E-033E-034E-05

3E-05- 1E-03- 4E-05

IE-OS | - 2E-05

RMEmin

7E-069E-056E-056E-OS2E-058E-051E-042E-043E-047E-05

3E-055E-052E-041E-04

1E-04

2E-041E-04

3E-056E-042E-038E-053E-053E-056E-042E-042E-042E-04

1E-04

max-I 2E-04---------------------

SE-04

9E-04

9E-04

2E-042E-033£-033E-047&03SE-036E-04SE-041E-022E-033E-032E-032E-045E-043E-034E-02SE-034E-04

-I 1E-03-! 5E-02---

6E-031E-034E-03

- 5E-03

IE-03 - 4E-022E-04

3E-041E-033E-053E-059E-056E-059E-05

-; 4E-04

- 1E-02

- j 2E-023E-04

- 2E-04

- 1E-02

- 4E-04

- 2E-04


CTEmm - max

2E-072E-061E-061E-064E-072E-063E-063E-066ET062E-068E-071E-065E-062E-063E-063E-065E-067E-07

IE-OS3E-052E-06

9E-07

9E-07

2E-05

5E-064E-063E-06

3E-06

2E-055E-06

8E-062E-057E-07

9E-073E-062E-06

------------------------

7E-063E-053E-053E-057E-067E-051E-048E-062E-042E-042E-052E-055E-045E-05

1E-04

7E-05

5E-06

2E-05

9E-05IE-032E-04IE-OS5E-052E-03

-( 2E-04-----------

3E-06 -

4E-OS1E-04

2E-041E-03IE-OS

3E-048E-04IE-OS

7E-063E-04IE-OS

6E-06

RMEmin

2E-062E-05

IE-OSIE-OS4E-062E-05

3E-053E-057E-052E-OS9E-06IE-OS6E-052E-053E-054E-055E-058E-061E-044E-04

3E-05

IE-OS

IE-OS

2E-046E-054E-OS4E-05

4E-05

3E-046E-05

9E-052E-048E-06

IE-OS

4E-05

2E-05

4E-05

.------------------------------------

-

max8E-05

3E-044E-043E-Q48E-058E-04IE-039E-053E-032E-032E-042E-04 .6E-036E-04IE-038E-046E-052E-04IE-031E-022E-032E-046E-042E-022E-034E-04IE-03

2E-031E-022E-04

4E-039E-031E-04

8E-054E-031E-04

6E-05


CTE = Central Tendency ExposureRME = Reasonable Maximum ExposureShading/boldface denotes cancer risk exceeding 1E-04 (upper end of USEPA's target cancer risk range).


from All Exposure Pathways

STATION

DP25DP26DP27DP28DP29DP30DP31DP32DP33DP34DP35DP36DP37DP38DP39DP40DP41DP42

MW03UMW05UMW2SWPH01WPH10

DPG-064DPG-082DPG-104DPG-140DPG-207MW-10SMW-11SMW-12SMW-13SMW-14SMW-1SMW-2SMW-3SMW-4SMW-9SMW2DMW-1DMW-3DMW-12SMW-13SMW-14SMW-1SMW-2SMW-3SMW-4SMW-9SMW2DMW-3D

AQUIFERZONE

UuUuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

NANANAUUUUuuuu

NANA


CTEmin

2E-061E-048E-056E-057E-052E-06IE-OS9E-051E-04ZE-043E-045E-053E-056E-051E-041E-041E-049E-051E-048E-052E-042E-058E-042E-034E-OS2E-05IE-OS4E-04ZE-042E-04

-------------------------------

1E-04 -1E-04 -1E-031E-043E-04 -1E-031 E-05IE-OS -

4E-05 -3 E-054E-OS -2E-052E-051E-042E-054E-051E-043E-063E-06IE-OS7E-06

max3E-052E-049E-OS2E-042E-043E-064E-054E-046E-042E-041E-038E-041E-041E-042E-033E-046E-041E-041E-048E-055E-049E-OS1E-037E-038E-048E-052E-047E-031E-034E-047E-048E-046E-031E-042E-034E-036E-054E-05

1E-033E-051E-04

4E-04- 6E-04- ! 4E-03- 5E-05- ! 1E-03- i 3E-03--

4E-05

3E-05

- 1E-03- 4E-05

RMEmm

2E-OS7E-046E-044E-045E-042E-051E-046E-041E-031E-032E-034E-042E-044E-041E-038E-04IE-036E-048E-045R=041E-032E-04SE-031E-023E-041E-049E-053E-032E-032E-031E-038E-048E-038E-042E-037E-031E-048E-OS

3E-042E-04

- 1 max---------------------------

2E-042E-036E-041E-03IE-032E-053E-043E-03SE-03tE-031E-02«E-039E-04IE-032E-022E-035E-037E-048E-046E-044E-037E-04SE-03SE-027E-036E-042E-03

- 6E-02- 8E-03- 3E-03- 5E-03--

6E-«3SE-02

- 1E-03- 1E-02

3E-024E-04

- 3E-04- 1E-02

3E-043E-04 - 9E-042E-04 - 4E-031E-041E-032E-043E-04

- SE-03

- 4E-02

- 4E-04

1E-021E-03 - : 2E-023E-OS3E-059E-OS6E-05

-! 3E-04

- 2E-04IE-02

- 4E-04


CTEmin - max

5E-07IE-OS9E-067E-068E-064E-072E-06IE-OS2E-052E-053 E-058E-064E-066E-062E-OSIE-OS2E-05IE-OS2E-052E-052E-053E-068E-05

- 2E-047E-063E-062E-067E-053E-052E-052E-OSIE-OS1E-042E-054E-051E-042E-062E-06IE-OS5E-068E-063E-063E-062E-055E-068E-062E-057E-079E-073E-062E-06

-----------------------------

^

8E-064E-05IE-OS4E-OS4E-056E-07IE-OS9E-051E-043E-053E-042E-043E-053E-056E-047E-051E-04IE-OS2E-OS2E-051E-04 .2E-052E-042E-032E-042E-056E-052E-032E-046E-05

- 2E-04- 2E-04- 2E-03--

3E-054E-04

- LE-03-1 IE-OS- 1 9E-06-

-

-

-

--

-

4E-047E-06

2E-05

1E-04

2E-04

IE-03IE-OS

- 3E-04- 8E-04-| IE-OS---

7E-063E-04IE-OS

RMEmin 1 -

5E-061E-047E-056E-OS7E-054E-062E-059E-052E-042E-043E-047E-053E-056E-OS2E-041E-041E-048E-052E-04IE-042E-042E-057E-042E-037E-OS3E-052E-057E-042E-042E-042E-04IE-04IE-032E-044E-04IE-032E-052E-05IE-045E-057E-054E-054E-053E-046E-OS9E-052E-048E-06IE-OS4E-052E-05

-----------------------

----

max9E-054E-04IE-044E-04 .4E-046E-06IE-049E-042E-032E-4J43E-032E-033E-043E-046E-037E-04IE-03IE-042E-04IE-04IE-032E-042E-032E-022E-032E-046E-042E-02

-1 3E-03------------

6E-042E-032E-032E-023E-044E-03JE-02IE-04IE-044E-037E-OS2E-04

-! IE-03-------

2E-03IE-022E-044E-039E-03IE-048E-05

-1 4E-03-j IE-04


CTE = Central Tendency ExposureRME = Reasonable Maximum ExposureShading/boldface denotes cancer risk exceeding IE-04 (upper end of USEPA's target cancer risk range).

Table 15. Summary of Uncertainties

Source ofUncertainty

Analytical data

Exposure pointconcentrations for

groundwater

Exposure pointconcentrations forVOCs in indoor air

Toxicity values (RfD,RfC, SF)

Chemicals notevaluated

Exposure pathwaysnot evaluated

Effect of chemicalinteractions

Comment

Relative errors may be largenear, detection limit

Highest detected value used asconservative estimate of long-

term mean

Values are calculated using amathematical models rather

than being measured

Some are interim; all haveuncertainty, especially

trichloroethylene

Probable Directionof Error

Either high or low

Probably high

Uncertain; morelikely high than low

Usually tend tooverestimate risk

Underestimate risks

Underestimate risks

Unknown

Probable Magnitudeof Error

Usually small

Uncertain; might belarge

Possibly large

Unknown; possiblylarge

Unknown; probablysmall compared tochemicals that were

evaluated

Unknown; probablysmall

Unknown; probablysmall

TABLE 16Comparative Analysis Using JMCF Criteria

f£?, ivi «' ,' '•?&i£-'f-^'£ ^r~-*c£'£?~^ 'ifyîf'^--'^'1' VJjS%Âlternative z — Momtoreav•Natural Attenuation (>m A) Extraction w/Insdtutional

-"•S'i'li"'" - ~**:-^j-'" ^'^^^•w^^t^-^-'^^y-^f''"'^^£ AtMaPlWQy^ O .— fcnnflnCCO JlBr^/

^Remâhoh-w/lMtifetibriiBi^

Jîât^^£Weaflneill|f

fipw/iaWtMtional»3

EffectivenessOverall Protection ofluman Health andinvironment

Compliance withRemedial ActionObjectives andARARs

ông-Tenniffectiveness

Reduction of Toxicity,Mobility and Volume

mprovements ingroundwater and vadosezone soil conditions achievedthrough natural attenuation.lowever, lack of 1C may

result in health risk above aevel of concern. Permanent

compliance with MCLs inoff-Site areas is predicted tooccur between 2022 and2057.

Achieves RAO's andcomplies with chemical-specific ARARs throughnatural attenuatioa Noocation-specific ARARs.

Permanence is achievedthrough natural attenuatioaSome risks associated withgroundwater use beforeHAO's are met.

Reduction in mobility,toxicity and volume throughnatural attenuatioa

Achieves improvements inrroundwater and vadose zonesoil conditions in the same timerame as Alternative 1 .rnplementation of 1C willminimize potential for humanlealth risk above a level ofconcern. Permanent compliancewith MCLs in off-Site areas is>redicted to occur between2022 and 2057.

Achieves RAO's in the sametime frame as Alternative 1 .Complies with chemical- andaction-specific ARARs. Nolocation-specific ARARs.

Protection achieved at the timeof 1C implementation.Reliability of 1C depends oneffectiveness of enforcementagency. Permanence achievedthrough natural attenuatioa

Reduction in mobility, toxicityand volume is the same as forAlternative 1.

Achieves improvements injroundwater conditions morequickly than under Alternatives 1and 2 by limiting migration ofCOCs to groundwater. Vadose zonesoils will reach RAO's in similar oronger time frame than under

Alternatives 1 and 2 due to reducedinfiltration and associated leachingof contaminants. Implementation ofC will minimize potential forluman health risk above a level ofconcern. Some reduction in theamount of time needed to achievejermanent compliance with MCLsas compared with Alternatives 1and 2 in off-Site areas may beac eve .

Achieves RAO's in a shorter timerame than under Alternatives 1 and2. Complies with chemical- andaction-specific ARARs. No.ocation-specific ARARs.

Protection achieved at the time of[C implementation. Reliability of1C depends on effectiveness ofenforcement agency. Permanenceachieved through naturalattenuation. Degree of effectivenessin accelerating achievement ofgroundwater RAO's is unknown.

Reduction in toxicity and volume isthe same as for Alternative 1 .Contaminant mobility is loweredthrough reduction in infiltratingwater.

Achieves improvements inproundwater and vadose zone soilconditions more quickly thanunder Alternatives 1-3 byremoving COCs from the inferredsource area. Implementation ofC will minimize potential forluman health risk above a level

of concern. Some reduction in theamount of time needed to achieve>ermanent compliance withVICLs as compared withAlternatives 1 and 2 in off-Siteareas may be achieved.

Achieves RAO's in a shorter timerame than under Alternatives 1 -3. Complies with chemical- andaction^specific ARARs. Noocation-specific ARARs.

Protection achieved at the time ofC implementation. Reliability ofC depends on effectiveness ofenforcement agency. Permanenceachieved through naturalattenuation. Operation ofremediation system will berequired for at least several years.Effectiveness (contaminant massrecovery) may be limited by Sitecharacteristics.

Contaminant mobility increasedthrough the discharge ofextracted soil vapor. Potentiallyhigher mobility than all otherAlternatives. Reduction incontaminant toxicity and volumeroughly similar to alternatives 1 -3.

Achieves improvements ingroundwater more quickly thanunder Alternatives 1 4 throughenhanced in-situ destruction ofCOC's. Implementation of 1C willminimize potential for humanlealth risk above a level ofconcern. Some reduction in theamount of time needed to achievesermanent compliance withvICLs as compared withAlternatives 1 and 2 in off-Siteareas may be achieved.

Achieves RAO's in a shorter timeframe than under Alternatives 1 -4. Complies with chemical- andaction-specific ARARs. No[ocation-specific ARARs.

Protection achieved at the time of[C implementation. Reliability of1C depends on effectiveness ofenforcement agency. Permanenceachieved through enhancednatural attenuatioa Multipleapplication of chemical additivewould be required. Effectiveness(degree of enhancement of COGbiodegradation) may be limitedby Site characteristics.

Reduction in mobility, toxicityand volume greater than underAlternatives 1-4 through COCdestruction.

Achieves improvements in off-Sitejroundwater more quickly thanunder Alternatives 1-4 (aidpossibly 6) through extraction ofcontaminated groundwater.Improvements in vadose zone soilswould occur at the same rate asunder Alternatives 1-3. •implementation of 1C willminimize potential for humanlealth risk above a level ofconcern. Compliance with' MCLs inoff-Site areas is predicted!to occurin 2017. However, perm'anentreduction in COCs in off-Siteareas may require continuedoperation of this alternativebeyond 2017 to prevent off-Sitemigration of COCs retrainingon-Site above MCLs.Achieves RAO's in a shorter timeframe than under Alternatives 1 -4.Complies with chemical- andaction-specific ARARs. No.ocation-specific ARARs

Protection achieved at the time of[C implementation. Reliability of[C depends on effectiveness ofenforcement agency. Permanenceachieved through extraction ofcontaminated groundwater andnatural attenuation of COCs invadose zone soils.

Contaminant mobility incthrough air stripper dischiReduction in contaminanand volume roughly simialternatives 1-4.

reasedirge.toxicityarto

See Alternative 7a.

See Alternative 7a.

See Alternative 7a.

Reduction inmobility, toxicityand volumepotentially greaterthan underAlternatives l-7athrough destructionof COCs by UVOxidation. •

See Alternative 7a.

See Alternative 7a.

See Alternative 7a.

See Alternative 7b.

TABLE 16Comparative Analysis Using NCP Criteria

.

ra^.^TITnKan'X^I Tnl*

AirStrippiflgw/Institutionali^*^a@esS^?x-5?-'.v_-: .';•

hort Termiffectiveness

Involves no further remedialaction.

No short-term risks asassociated with this alternative.

Short term risks are similar to thoseunder Alternatives 1 and 2.

Short term risks are similar tothose under Alternatives 1 and 2.Risks associated with vaportintrusion into future on-Sitestructures may be reductedthrough operation of a SVEsystem. Risks associated withdischarge of soil vapor expectedto be negligible.

Short term risks are similar tothose under Alternatives 1 and 2.

Short term risks are simila • to thoseunder Alternatives 1 and 2 Risksassociated with discharge i >f soilvapor expected to be negligible.

See Alternative 7a. See Alternative 7a.

!mplementability

Technical Feasibility No Action Required. Sto technical issues areassociated with this alternative.

All required technologies arereadily available.



Groundwater modeling indibates itmay not be possible to establishlydraulic capture of entire plumealong western Site boundary w/outadversely affecting overlappingpetroleum plume to the north.

See Alternative 7a. See Alternative 7a.

AdministrativeFeasibility

tfo Action Required. The willingness of themunicipality to administer the[C has not been evaluated. Anagreement would have to bereached with the City of WoodsCross to enforce a groundwateruse restrictions.

See Alternative 2. See Alternative 2. See Alternative 2. See Alternative 2. See Alternative 2. The POTW will not acceptuntreated discharge. Notimplementable.

Availability ofServices and Materials

No Action Required. Services and materials arereadily available.

See Alternative 2. See Alternative 2. See Alternative 2. See Alternative 2. See Alternative 2. See Alternative 2.

Anticipated StateAcceptance

Assessed during FFScomment period.

Assessed during FFS commentperiod.




Assessed during FFS commentperiod. j

Assessed duringFFS commentperiod.


Anticipatedommunity

Acceptance

Assessed during FFScomment period.





Assessed during FFS commentperiod. i

Assessed duringFFS commentperiod.


Cost

Capital Costs $0 $9,531 $89,040 $53,945 $149,848 $70,687 $224,197 $49,109Present Value O&M

Costs $0 $58,167 $58,167 $92,942 $42,694 5260,261 $397,052 $152,986

Periodic Costs $0 $0 $11,435 $136,258 $4,461 $4,460 $4,461

Present Value $0 $67,698 $147,207 $158,322 $328,800 6335,409 $625,709 $206,556

W.S. Hatcch Co.Focused Feasibility Study Final ReportTsble9-l

TABLE 17Chemical-Specific ARARs

Standard, Requirement or Criteria. Description PotentiallyApplicable

PotentiallyRelevant andAppropriate

: Comment'?•;

FEDERALClean Water Act (33 USC Sect. 1351-1376)Ambient Water Quality Criteria (40 CFR Part131; Quality Criteria for Water, 1976, 1980,1986, 1987; Ambient Water Quality Criteriafor Selenium, 1987)

Requires EPA and states toestablish ambient water qualitycontrol criteria (AWQC) andstandards, respectively, for surfacewater based on use classificationsand the criteria stated underSections 304(a) and 303 of theClean Water Act.

No No

Federal (or State) freshwater AWQCs are notconsidered to be ARAR as no surface waterimpacts have been identified or are anticipated.Standards would be applicable to any surfacedischarges of contaminated water tojurisdictional waters, but not discharges toPOTWs.

lean Air Act (42 USC Sect. 7401-7642)National Ambient Air Quality Standards (40:FR Part 50)

Establishes ambient air qualitystandards for certain "criteriapollutants" to protect public healthand welfare.

No No No impact on NAAQS are anticipated by currentsite conditions or the remedial action.

National Emissions Standards for HazardousAir Pollutants (40 CFR Part 61)

Establishes emission standards forcertain industrial pollutants andsources.

No No

NESHAP's are not considered to be ARARsbecause estimated air emissions from Site wastesare anticipated to be well below levels ofconcern, as described in the baseline riskassessment included in the remedialInvestigation Report (Hatchco, 2003).

National Primary Drinking Water Standards0 CFR Part 141•R 8750 (1990)

Establishes maximum contaminantlevels (MCLs) for specificcontaminants which are health-?ased standards for public drinkingwater systems.

Yes

Although there are no current or anticipatedimpacts on public drinking water systems, MCLsmay be applicable under UAC R311-211-5,unless a less stringent action level is establishedunder the rule, an alternate corrective actionconcentration limit (ACACL) is adopted, or anACL is established under CERCLA.


Standard, Requirement or Criteria Description PotentiallyApplicable

Potentially:Relevant andAppropriate

Comment'

National Secondary Drinking Water Standards40 CFR Part 143

Establishes secondary maximumcontaminant levels (SMCLs) whichare non-enforceable guidelines forpublic drinking water systems toprotect the aesthetic quality of thewater.

Yes

Although there are no current or anticipatedimpacts on public drinking water systems, MCLsmay be applicable under UAC R311 -211 -5,unless a less stringent action level is establishedunder the rule, an alternate corrective actionconcentration limit (ACACL) is adopted, or anACL is established under CERCLA.

Maximum Contaminant Level Goals(MCLGs) PL No. 99-339, 100 Star. 642(1986), FR 8750 (1990)

Establishes drinking water qualityjoals set at a level at which noadverse health effects may arisewith an adequate margin of safety.

There are no current or anticipated impacts onpublic drinking water systems.

No No

STATEDefinitions and General Requirements of UtahWater Quality Act UAC R317-1

Provides definitions and generalrequirements for waste dischargesto waters of the State of UtahEstablishes use designationsStatewide Water QualityStandards.

Yes

Would be applicable to any discharge of treatedor untreated groundwater to surface water, butnot discharges to a POTW.

Utah Primary Drinking Water Standards UACR309-200-5

Establishes state primary drinkingwater standards and/or actionlevels.

Yes

Although there are no current or anticipatedimpacts on public drinking water systems, MCLsmay be applicable under UAC R311-211-5,unless a less stringent action level is establishedunder the rule, an alternate corrective actionconcentration limit (ACACL) is adopted, or anACL is established under CERCLA.


Standard, Requirement or Criteria DescriptionPotentiallyApplicable:


Comment

Groundwater Quality Standards UAC R317-6-2

Establishes state groundwaterquality standards.

Yes

Considered applicable for protection ofuncontaminated groundwater and relevant andappropriate for corrective action unless analternate corrective action concentration limit(ACACL) is adopted, or an ACL is establishedunder CERCLA.

Alternate Corrective Action Concentrationimits UAC R317-6-6.15G

Allows for the proposal of alternatecorrection action concentrationimits (ACACLs) that are higher

than those specified in UAC R317-6-2.

ACACLs may apply.

Yes

Corrective Action Clean-up Standards at USTand CERCLA sites UAC R311 -211 -5

Provides minimum standards andalternatives for cleanup ofregulated substances, hazardousmaterials, and hazardoussubstances at CERCLA sites inUtah.

Applicable.

Yes

TABLE 18Action-Specific ARARs

Standard, Requirement or Criteria DescriptionPotentiallyApplicable

PotentiallyRelevant andAppropriate:

Comment

FEDERALClean Water Act (33 USC Sect. 1351-1376) Ambient Water Quality Criteria(40 CFR Part 131; Quality Criteria forWater, 1976, 1980, 1986, 1987; AmbientWater Quality Criteria for Selenium,1987)

Requires EPA and states toestablish ambient water qualitycontrol criteria (AWQC) andstandards, respectively, forsurface water based on useclassifications and the criteriastated under Sections 304(a) and303 of the Clean Water Act.

Yes

Standards may be applicable to alternatives thatprovide for surface water discharges ofcontaminated water to jurisdictional waters (notincluding discharges to POTWs).

llean Air Act (42 USC Sect. 7401-7642)^Jew Source Performance Standards (40FR 60)

Establishes emission standards forcertain categories of industrialstationary sources. No No

No impact on NAAQS are anticipated by currentsite conditions or the remedial action.

;olid Waste Disposal Act (SWDA) asamended by the Resource Conservationand Recovery Act of 1976 (RCRA) (42USC Sect. 6901-6987) Criteria forClassification of Solid Waste Disposal'acilities and Practices (Subtitle D) (40TR Part 257)

Establishes criteria for use indetermining which solid wastedisposal facilities and practices3ose a reasonable probability ofadverse effects on health.

None of the remedial alternatives include theconstruction of a non-hazardous solid wastelandfill.

No No

Solid Waste Closure (40 CFR 259.60 b, Placement of Cap over solid wasteandfill. No No

None of the remedial alternatives include theconstruction of a non-hazardous solid wastelandfill.

dentification and Listing of HazardousPastes (Subtitle C) 40 CFR part 261

Defines those solid wastes whichare subject to regulation ashazardous wastes under 40 CFR

arts 262-265 and Parts 124, 270,and 271. No No

Although some remedial alternatives may involvethe treatment or disposal of TCE and PCEcontaminated groundwater, these extractedgroundwaters are not expected to exhibit hazardouscharacteristics and are thus expected to fall underthe 40 CFR 261.3(a)(2)(iv) exemption. Thus,RCRA Subtitle C is neither applicable or relevantand appropriate.


Standard, Requirement or Criteria Description PotentiallyApplicable


Comment;

Standards Applicable to Generators ofHazardous Waste (Subtitle C) 40 CFRPart 262

Establishes standards forgenerators of hazardous waste. No No

None of the remedial alternatives involve thegeneration of hazardous waste, as above.

Standards Applicable to Transporters ofHazardous Waste (Subtitle C)40 CFR Part 263

Establishes standards which applyto persons transporting hazardouswaste within the US if thetransportation requires a manifestunder 40 CFR Part 262.

None of the remedial alternatives involve thetransportation of hazardous waste off-site.

No No

Standards for Owners and Operators ofhazardous Waste Treatment, Storage,and Disposal Facilities (Subtitle C)40 CFR Part 264

Establishes minimum nationalstandards which define theacceptable management oflazardous waste for owners andoperators of facilities which treat,store, or dispose hazardous waste.

No No

None of the remedial alternatives involve thetreatment. Storage, or Disposal of hazardouswastes, as above.

interim Standards for Owners andOperators of Hazardous WasteTreatment, Storage, and DisposalFacilities (Subtitle C)|40 CFR Part 265

Establishes minimum nationalstandards which define theacceptable management ofhazardous waste during the periodof interim status and untilcertification of final closure or ifthe facility is subject to post-closure requirements, until post-closure requirements, until post-closure responsibilities arefulfilled.


No No

iazardous Materials Transportation Act49 USC Sect. 1801-1813; 49 CFR Parts07,171-177)

Regulates transportation oflazardous materials. No No



Standard, Requirement or Criteria

Land Disposal40 CFR Part 268

Underground Injection ControlRegulations 40 CFR 1 44- 1 47

National Pollutant Discharge EliminationSystem 40 CFR parts 122, 125

Guidelines establishing Test Proceduresbr the Analysis of Pollutants40 CFR 136

Description -

Establishes a timetable forrestriction of burial of wastes andother hazardous materials.

Provides for protection ofunderground sources of drinkingwater.

Requires permits for the dischargeof pollutants from any pointsource into waters of the UnitedStates.

Specific analytical procedures forNPDES applicants and reports.

Potentially;Applicable

No

No

Yes

Yes


No

Yes

": , - '•'• -• • .'.•:,r:'J:;i;;Corriment, . ; . _ ;.; ' . ' • • ;'A"~"" ;'-'':'^.

LDRs are inapplicable because any placement ofhazardous waste (if any) is anticipated to occurwithin a Area of Contamination (Site boundaries).

Potentially relevant and appropriate to injection ofchemical additives. However, in no event would apermit be required for alternatives involvinginjection of chemical additives, as provided underCERCLA Section 12 l(c).Potentially applicable only to alternatives whereremedial action involves discharge to surfacewaters. Discharge options include discharge tostorm sewer. Would not apply to discharges toPOTW.Potentially applicable to alternatives wherecontaminated waters would be discharged tosurface waters. Would not apply to discharges toPOTW.

STATE

Fugitive Dust Control UAC R307-101

Small Source Exemption de-minimisemissions UAC R307-413-2

Well Drilling and Completion StandardsUACR655-4

General requirements forcompliance with NationalAmbient Air Quality Standards.

Establishes requirements forexemption of a new source of airpollution from the notice of intentand approval order requirements.

Establishes standards for drillingand abandonment of wells.

Yes

Yes

Yes

Earthwork would be required under the alternativeinvolving capping

New sources of air pollution may result fromtreatment of contaminated soil by vapor extractionor by treatment of groundwater by air stripping.Emissions will not exceed the 5 ton/yr limit underthis regulation.Requirements are applicable for installing orabandoning wells.


Standard, Requirement or Criteria Description•',.. PotentiallyApplicable

PotentiallyRelevant and

/AppropriateComment

Hazardous Waste GeneratorRequirements UAC R315-5

Establishes standards forhazardous waste generators.

No No

Although some remedial alternatives may involvethe treatment or disposal of TCE and PCEcontaminated groundwater, these extractedgroundwaters are not expected to exhibit hazardouscharacteristics and are thus expected to fall underthe 40 CFR 261.3(a)(2)(iv) exemption. Thus,RCRA Subtitle C is neither applicable or relevantand appropriate.

Jnderground Injection Control Program,UAC R317-7

Prohibits underground injectionexcept as authorized by permit.

No Yes

Potentially relevant and appropriate to the injectionof additives. However, in no event would a permitbe required for alternatives involving injection ofchemical additives, as provided under CERCLASection 121(c).

Discharges to Surface Water UAC 317-8, UAC R317-2-3

Protection of surface watersagainst degradation resulting frompoint source discharges.Maintains and protects existing instream water uses includingjrotecting streams with higherwater quality than the establishedstandards.

Yes

Potentially applicable to alternatives wherecontaminated waters would be discharged tosurface waters. Would not apply to discharges toPOTW.

Definitions and General Requirements of|ProvidesUtah Water Quality Act UAC R317-1

definitions and generalrequirements for waste dischargeso waters of the State of Utah

Establishes use designationsStatewide Water QualityStandards.

Yes

Would be applicable to any discharge of treated oruntreated groundwater to surface water, but notdischarges to a POTW.

Table 19 - Estimated Costs for the Selected Remedy

' '. ' ' '•-'••. . •;.:•"•:• ' •'• '' •••• - • • Capital-Cost-' '••• •" ' ' •;•-": • > ^ •1^^^^.^

Remedial Design

Drilling

injection (source and one Barrier)

Baseline Monitoring

Bioaugmentation

Capital Total

0 & M

Monitoring (Years 1-15)

injections (Years 2,4,6)

5-Year Review

o & M Total

Sub-Total (Capital and O&M)

$75,000

$147,871

$236,224

$21,350

$12,422

$492,867

..•COSt< ' ;,•;••; v-v: •••>"•• <:'-v,:;-;.,.v <•. v -f^:;

$233,122

$337,635

$66,000

$636,757

• ••''-• ; ' . $1,129, 624X:"? ; : ?;v-J^ \'^

Oversi ght/Management Cost £Construction Management/Tech Support(15%)

Administration (10%)

Contingency (25%)

Total

Present worth Cost Total

$169,450

$112,966

$282,416

$564,832

r-^v\';;"^iv694>-456;-^''Y;';v;:""';- .." • -"'

This cost estimate table is a preliminary full-scale cost estimate, based on a Technical Memorandum CostEstimate for a Full-scale Remediation for OU1 (September 18, 2006), and the best available informationregarding the anticipated scope of the Selected Remedy. Changes in the cost elements are likely to occur asa result of new information and data collected during the engineering design. Major changes may bedocumented in the form of a memorandum in the Administrative Record file, an Explanation of SignificantDifference, or a ROD amendment. This is an order-of-magnitude engineering cost estimate that is expectedto be within -30 to +50 percent of the actual project cost.

APPENDIX A

I11""

11111111I1Iiiiii

'^^fer"•/ ooscH < ™/ . i J t i - ' i fMi ' J l NATIVE

RECORD PUBLICDOCUMENT

ENVIRONMENTAL PROTECTION AGENCY

PROPOSED CLEANUP PLAN^ £- /</**>"

ORIGINALBOUNTIFUL /WOODS CROSS/ 5TH SOUTH

PCE PLUME SUPERFUND SITEOPERABLE UNIT 1

PUBLIC COMMENT MEETING

August 24, 2004

Bountiful City Hall790 S. 100 E.

Bountiful, Utah

.

^HfjjimlUlReporters, Inc. 10 West 100 South, Suite 250 • Salt Lake City, Utah 84101 l^flA'Tt^tQ(801 ) 746-5080 phone • (801 ) 746-5083 fax • 1 -866-31 0-OEPO • www.reportersinc net P4:

fflC

IIIIiiiiiiiiiiiiiii

1 August 24, 2004 6:05 p .m.

2 __oOo--

3 P R O C E E D I N G S

4 __00o--

5 MS. LINN: We will be talking about the

6 Bountiful/Woods Cross/Fifth South PCE Plume Superfund

7 site. And we will be going over the proposed plan at

8 least in general and talking about our preferred

9 alternative. We will be hopefully giving you information

10 and explaining things to you. You'll have an opportunity

11 to ask questions, make comments. You know, it's your

12 meeting, and we want to hear what you think about what's .

13 going on. So that's what we're here to hear. We have, it

14 looks like, more of us than the public here. But there

15 are several players involved in this site, starting with

16 the Environmental Protection Agency.

17 I'm the Peggy Linn, the community involvement

18 coordinator, so if you have questions, I'm probably the

19 easiest one to get ahold of, and my information is in the

20 proposed plan. The project manager is Mario Robles with

21 EPA; with the Utah Department of Environmental Quality,

• 22 our project manager is Michael Stork; and then with the

23 Water Quality Division of Utah state is Ed Hickey -- this

24 is a test -- and Scott Everett, and I didn't get your

25 position, but he's also with the Utah Department of

HEIDI HUNTER * CCR, RPR 2

1 Environmental Quality, toxicologist. And then we have

2 Wendy O'Brien with EPA who is our toxicologist. And I

3 think that's all the agency people except for one more

4 who's coming in,.and this is Dave Allison with the State

5 of Utah. He's a community involvement specialist or

6 coordinator or whatever they call them in Utah. And so

7 he's probably the easiest one to get ahold of for the

8 State if you have any questions, and then we can direct

9 you where you need to talk to others.

10 I don't see a representative, or maybe I do and

11 I haven't met him yet, but with HatchCo that's our

12 potential responsible party in this, and so he -- so

13 HatchCo is another one of the team members of this whole

14 group. I don't want to skip anything here on my little

15 reminders.

16 We also have a court reporter tonight who is

17 taking down everything I say, every little mistake I make,

18 and this is Heidi Hunter, our court reporter. And we will

19 have a transcript available after she's had time to put it

20 together and get it to us. And if anybody did not receive

21 a copy of the proposed plan or would like an extra copy,

22 we will have some extra copies back there. We have some .

23 handouts. We have a handout of the presentation and then

24 some handouts about some of the different -- like the TCE

25 and PCE if you want to learn more about those, and some


11II1fIIIiIIIIIIIIi

1 fact sheets on some of the things that will be discussed

2 later in the program.

3 And if anyone did not sign in, would you please.

4 It helps us update our mailing list and helps us keep

5 track of who -- how many we actually had in attendance.

6 Mario is going to give a short presentation

7 about the proposed plan and the preferred alternative.

8 And after his presentation, then we will turn it over to

9 questions and a comment period. And if you get up to make

10 a comment, ask a question, I ask that you be sure and

11 speak loudly. First of all, state your name, first and

12 last name, and then spell your last name and whoever

13 you're affiliated with, if it's a company, an agency, or

14 if you're a citizen, we, of course, would love to hear we

15 have actual citizens here because that's who we really

16 want to get to.

17 So we will give you time then to comment and ask

18 questions. And we ask that you try to focus your comments

19 and questions on the proposed plan. That's what we're

20 here to discuss tonight is this proposed plan for this

21 operable unit. And so if we can focus on that, that will

22 make the evening go a lot better.

23 And again, let me just say that you need to

24 speak loudly because I'm a stickler about that, and I'll

25 be bugging you if you don't speak loud enough for me to

HEIDI HUNTER * CCR, RPR . 4

I

1 hear from the back of the room;

2 So with that, I will turn it over to Mario, and

3 once again, thank you for coming. A couple of other

4 people snuck in. Are they people I should introduce?

5 MR. ROBLES: I know Ken Napp. He's from the

6 HatchCo Company.

7 MR. RANDALL: I'm Brett Randall also

8 representing HatchCo Company.

9 MR. ROBLES: Thank you very much for coming.

10 For the members of the community, I put up my

11 first slide. I apologize, but I think it will give you a

12 better idea of the plumes that we have at this operable

13 unit. Then I'm going to take you to the plume in HatchCo

14 and that's hopefully the only issue we are going to be

15 discussing because we are going to be here in the future

16 discussing the other plumes.

17 At the Bountiful/Woods Cross Superfund Site, NPL

18 site, we have several plumes. I think that you should be

19 aware that there are severe sources of contamination,

20 there is just not one. The source that we are going to be

21 focusing our discussion is the HatchCo, and that is this

22 little plume over here. These other plumes belong to

23 another remedial investigation that we are doing right

24 now, that remedial investigation should be completed at

25 the beginning of next year, and then we are going to have


I1I11•1.

I1m1I1111I1i1

* .

i

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

•

another public meeting so we can discuss that remedial

investigation.

But for now, this is the area that EPA has

investigated and all of these plumes essentially are

flowing together. So they are merging, as you can see, on

this little area.

We have two plumes. The TCE, which is comingr^ ft

from an up gradient source, and then we have the -£€£-7 ^fe-fLy

known as Trichloroethylene, which is essentially

originating at the HatchCo property. You can see the red

lines, they stop right here, and there is a reason for

that, the plume really continues, and it's a little bit

larger than it shows in that figure.

See this red box over here, next one, that's

what it used to be inside that red box. W.S. HatchCo

Company, the HatchCo Service Company, and Jack Kelley, at

different times they operated a trucking facility at this

site. At the time -- at the peak of the operations, they

had about 75 trucks and about 125 employees. They had

several potential sources of contamination. They had an

underground storage tank, they had oil-water separator,

and they also had a wash rack with a French drain that was

sort of in between the site.

The whole site at the time they were using it

included about 13 acres of property. Now the site was


1 divided and essentially is about 3 acres. Through the

2 operations, they transported petroleum products, petroleum

3 solvents, asphalt, oil petroleum. On the records they

4 also transported some fruits and perhaps some food

5 products.

6 They had -- through the years, they had several

7 spills, leaks from those trucks', potentially they had also

8 some discharges to the surface that went into the soils

9 and eventually migrated into the ground water.

10 Essentially this.is the entrance to 1-15. This

11 is 500 South. This is street over here, which you cannot

12 see, is 700 South, and this one is 800 West.

13 So we completed our remedial investigation. Ken

14 Napp, over here, he collected many, many samples. They

15 installed many monitoring wells to monitor the ground

16 water. The result of the remedial investigation is that

17 we really are not concerned with the soils, with the

18 surface soils, but the central portion of the site is

19 contaminated with solvents, like TCE, vinyl chloride, and

20 other petroleum products. There is Naphthalene, there is

21 diesel fuel, and others, contamination.

22 Out at this facility, we did our risk

23 assessment, actually we did two risk assessments. HatchCo

24 did a risk assessment. EPA did another risk assessment

25 for Operable Unit 2 that we are going to discuss at a


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1 later time. The interesting thing is that pretty much

2 both risk assessments came to the same conclusion, that

3 the water should not be used for drinking because it's

4 contaminated, and that the water should not be used for

5 indoor use within the boundaries of the plume.

6 What I mean by "indoor use," I mean if you take

7 a shower, you know, the vapors coming from that, that

8 water may not be good for you. And essentially the area

9 that concerns me would be the area within this boundary

10 where the contamination is the highest, and also the

11 contamination that is coming from the other plume, so it's

12 not just this plume.

13 Ecological concerns, we really don't have any

14 ecological concerns. There is no nice natural habitat.

15 We are not concerned about plants, wildlife, or animals.

16 The site is industrial, tanks and heavy traffic, and it's

17 not conducive to wildlife. And we really did not look

18 into endangered species, whatever my toxicologists are

19 concerned about the endangered species in the area.

20 So out of all of the investigations that we did

21 and the risk assessments we did, we had cleanup"

22 objectives. The first objective is to protect human

23 beings from exposure to contaminated ground water, and the

24 other one is to restore ground water to a beneficial use

25 in the future, I mean, long-term beneficial use.


1 So with those clean-up objectives, the team, the

2 EPA, the state, and HatchCo essentially came with these

3 clean-up alternatives.

4 I'm missing Number 5 over here, but there is a

5 reason for, during screening process, that alternative was

6 eliminated really early, didn't make it to the final

7 alternative.

8 We have the no action. The no-action

9 alternative, we have to include it, as a reference point

10 so we can compare it to the other alternatives.

11 All of the other alternatives are described in

12 the proposed plan. And I believe that you have a copy of

13 the proposed plan. You can read about it. Or if you have

14 any specific questions about the other alternatives, I

15 would like to discuss them with you, otherwise we would

16 like to move forward.

17 One important point over here is institutional

18 controls. Normally these alternatives would be

19 protective. We have controls to keep people from drinking

20 this water. So the State and EPA, we are going to start

21 discussing on ways that we can prevent or prohibit the

22 installation of wells in this area. So this is in

23 progress. And by the time we have the decision, we should

24 be able to come into the agreement what institutional

25 controls we should have for this site.


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So out of all these alternatives, there are two

alternatives that we choose, the first one: Monitor-

natural attenuation; and the second one, enhanced in-situ

biological/chemical bioremediation. Those are the ones

that EPA and the State feel that are appropriate for this

site.

This meeting is for you to ask any questions

about these alternatives as related to HatchCo to provide

comments so that we can incorporate those comments and

provide response to those comments when we issue the

decision. So if you have any questions, this is the time.

MS. LINN: Any comments, any concerns, anything

you would like explained a little bit more?

MR. FRANK: On the whole presentation or just on

that section?

MS. LINN: This is the whole presentation.

MR. FRANK: On 14S -- well, plume, are there any

indications where that's coining from?

MR. ROBLES: There is.

MS. LINN: Just a minute, can you state your

name for us, please, and tell us your affiliation, citizen

or whatever.

MR. FRANK: My name is George Frank, and I work

for Holly Refinery, the Woods Cross Refinery across" the

street, city corner and whatever.


1 MR. ROBLES: As stated in the proposed plan, and

2 I believe you have a copy of it, the concentrations pretty

3 much start right here at HatchCo. This is where the

4 source of this contamination is, then the concentrations

5 decrease and the --

6 THE REPORTER: I'm sorry, I can't hear you.

7 MR. ROBLES: On HatchCo on the property, where

8 the plume starts, the concentrations are significantly

9 high,- the background, the concentrations go down. At the

10 location where AW 14S is, they go up again. So one of the

11 conclusions of the remediation investigation, our study,

12 is there is potentially another source there, and I think

13 that -- yes, there is a potential, but we cannot tell for

14 certain if that's the case.N

15 And the reason that that's the case is because

16 EPA, through the other operable unit, collected some

17 ground water and some soil samples from a zone on top- of

18 the ground water that is no saturated, and out all of

19 those samples, we really didn't get any significant

20 detects.

21 MR. STORCK: There's probably 25, 30 samples

22 that's taken a direct push and there was one hit and at .9

23 micrograms per liter. So it was nothing to show any

24 significant source, at least from what we saw from those

25 samples.


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1 MR. ROBLES: So it is possible, you know, but I

2 have to make the decision whether or not I'm going to

3 spend a lot of money trying to figure that source or I'm

4 going to spend money fixing the-problem, okay. That's

5 another issue that we need to resolve within the near

6 future.

7 MR. FRANK: That is not to further investigate

8 that at this time?

9 MR. ROBLES: Yes. That is the reason that I

10 recommend a pilot for this. We are going into that.

11 That's one of the reasons. Any other questions?

12 MS. PASCOE: I'm Carma Pascoe and we have

13 property at 1500 West and Fifth South. I guess I really

14 don't understand any of this, but my question concerns

15 this plume we're talking about, you showed up there went-

16 as far west as 8th West?

17 MR. ROBLES: Can we go back to -- I guess.

18 CITIZEN: I guess I couldn't -- I want to know

19 how far back that plume is.

20 MR. ROBLES: Let's go back almost to the

21 beginning. That's good. This over here, this is 1100

22 West. This is 1100 West. This one I believe is — no,

23 this one is 500 South. The plume is largely made of

24 HatchCo. According to the reports, it is possible that we

25 have another source. it continues over here. It goes


1 around this way. We have detected -- on some of these

2 domestic wells, some of these dots, we have detected

3 concentrations of PCE, and we have detected concentrations

4 of TCE.

5 I think that the argument could be made where is

6 that coming from? At this point, essentially we don't

7 care. We care that we have the detected some •

8 concentrations of PCE and TCE. I don't know if they are

9 related to this plume or they are related to this plume.

10 MS. PASCOE: Or whether they're getting

11 together?

12 MR. ROBLES: Excuse me?

13 MS. PASCOE: Or whether they're getting together

14 and they're all going together at a certain point.

15 MR. ROBLES: Yes. Eventually they are going to

16 merge, but we don't know where that point would be down

17 this area, because they are just detects.

18 MS. PASCOE: But that plume is still moving west

19 and north and south, correct?

20 MR. ROBLES: If the plume is still moving --

21 MS. PASCOE: Or is it just going to be

22 stationary from now on if nothing is done?

23 MR. ROBLES: The modeling that came up

24 essentially is saying that the plume, the maximal spread

25 it could reach. He has some predictions that he's


III1IIiiiiiiiiiiii

1 modeling and that's the case.

2 In my opinion, the modeling studies that we did,

3 we worked with Ken, with HatchCo with some of their

4 modeling, but it's just modeling. What you put in is what

5 you put out. For certain I cannot tell you, but the

6 numbers show that -- according to this report', that is

7 pretty much stable.

8 MS. PASCOE: Thank you.

9 MR. ROBLES: Any other questions?

10 MS. PASCOE: I have another one.

11 MR. ROBLES: Go ahead.

12 MS. PASCOE: Because I'm here to learn. You're

13 talking about two propositions, one you're talking about

14 the natural -- the natural thing, and then we're talking

15 about adding something to the soil.

16 MR. ROBLES: To the ground water.

17 MS. PASCOE: To the ground water. And where do

18 you start treating the ground water? Do you start it at

19 HatchCo? Could you -- where do you start?

20 MR. ROBLES: Well, the plan is to start at

21 HatchCo, Ma'am. The plan is to start at HatchCo. And

22 what we are going to be doing -- depending on the public

23 comment period -- essentially, is injecting food-grade

24 products into the aquifer and this will accelerate the

25 biodegradation, and essentially would turn that into


1 eventually harmless compounds.

2 MS. PASCOE: How long does it take for the

3 additive that you put in to start the cleanup versus the

4 natural cleanup that's now in the process?

5 MR. ROBLES: If we allow the natural cleanups,

6 some of the estimates that we have it's going -- it could

7 be I believe 2027, from 2027 to 2057. I think that's the

8 numbers that we have on the model.

9 MR. NAPP: The modeling shows that natural --

10 essentially, if you don't do anything is allow this to run

11 its course, as Mario said, modeling is modeling, so you

12 have to sort of speculate. And what you do is you input a

13 range of numbers so that you try to capture the most

14 conservative against liberal points, and that range

15 produced the predicted cleanup time between 2020 and 2057

16 is the year, so 18 years to 53 years, something like. My

17 name is Ken Napp, and I work for HDR Engineering. I was

18 retained by HatchCo. And at that po.int the ground water

19 outside of the HatchCo property is predicted to reach the

20 drinking water standard.

21 MS. PASCOE: 2020 versus 2058?

22 MR. NAPP: Somewhere in that time frame. 'The

23 most optimistic would be 2020; most pessimistic would be

24 2057.

25 MR. ROBLES: The good thing is my grandson is


IIiiiiiiiiiiitititi

1 going to be working then on this project because I will be

2 gone.

3 MR. BANGERTER: My name is a Larry Bangerter.

4 I'm from here in Bountiful.

5 I just have a question. I'm curious if the

6 drought is leaching some of the chemicals into other

7 chemicals causing it to draw itself to each other, mix.

8 Sometimes you get a leaching effect on chemicals where

9 they join, and they'll produce toxins that won't quit and

10 that drought situation could be driving this thing.

11 MR. ROBLES: You know, it is possible, and the

12 reason I don't want to go there is because that is part of

13 the operable units from Number 2, Operable Unit Number 2.

14 What we found on the study is the ground water is going

15 down significantly. That reverses sometimes, especially

16 over there where MW14 is. The latest data that we got is

17 essentially the gradient reverses slightly to the east,

18 but essentially -- we can discuss that later if you want

19 to talk about that specific point.

20 Any other questions?

21 MR. ROBLES: Thank you very much. Ma'am,

22 another question from you?

23 MS. PASCOE: No.

24 MR. ROBLES: Your house is 1500. You're way

25 over there.

HEIDI HUNTER * OCR, RPR 16

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MS. PASCOE: Just want to know about the plume.

I was interested and I came because I wanted to learn a

couple of things. You've helped me somewhat, now maybe I

can better understand the report that I'm reading.

MR. ROBLES: If nobody has any questions, we

would like to open up for public comments and that will be

my last slide all the way to the last one.

MS. LINN: The public comment period is opened

on August 7th and will be open until the close of business

on September 7, and you can mail in your comments, you can

e-mail your comments. If you would like to make your

comments tonight and just speak them and be done with it,

that's the purpose of the court reporter.

And we have Mario's address up there and his

e-mail address, and that information is also on the back

of the proposed plan.

MR. ROBLES: Any questions or comments from

anyone? Okay, if there are no comments, I guess we close

the meeting.

MS. LINN: I appreciate the comments and

questions that we've had thank you very much for coming

out.

(The proceedings concluded at 6:34 p.m.)


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C E R T I F I C A T E

State of Utah )) ss.

County of Salt Lake )

This is to certify that the proceedings wastaken before me, Heidi Hunter, a Registered ProfessionalReporter and Notary Public in and for the State of Utah,residing in Salt Lake City;

That the proceedings was by me reported instenotype, and thereafter caused to be transcribed intotypewriting, and that a full, true, and correcttranscription of said testimony so taken and transcribedis set forth in the foregoing pages, numbered16, inclusive.

from 2 to

I further certify that I am not of kin. orotherwise associated with any of the parties to said causeof action, and that I am not interested in thethereof;

WITNESS MY HAND and official seal atCity, Utah, this 13th day of September, 2004.

My Commission Expires:

November 5, 2006

. s

Ll^dl 'WJJJ&H«/idi Hunter, RPR

/gH&v HE80S HUNTER/ffffiara JflSJcSTSii a'UBS iSsSSSB"^3S& CTATEOFUTAH

event

Salt Lake


APPENDIX B

EPA Responses to Hatchco CommentsOn the Proposed Plan

For Bountiful Woods/Cross PCE NPL SiteOU1 (Hatchco)

The Environmental Protection Agency (EPA) provides the following responses to W.S.Hatch Company (Hatchco) comments dated October 8, 2004. Please note EPA'sresponses are provided in Italic font.

Introduction to Comments

In order to put its comments in context, Hatchco provides this short introduction,summarizing several key facts that must be considered in the selection of any remedy forOU1.

• The discovery of contamination at the Hatchco property (the Site) in themid-1990's prompted Hatchco to take multiple remedial actions, including thevoluntary removal, treatment and disposal of contaminated soils. Because theexcavated soils were associated with contaminant release points such as a formerfrench drain, the soils removed by Hatchco contained relatively high contaminantconcentrations as compared with contaminated soils remaining at the Site. Inaddition to source remediation, Hatchco voluntarily initiated active treatment ofgroundwater in 1998.

Response - EPA acknowledges and has taken into consideration the cleanupactions Hatchco applied to its property. However, consistent with the NCPSection 300.435, ". . .RD/RA activities shall be in conformance with the remedyselected and set forth in the ROD or other decision document for the site. TheProposed Plan presents the first remedial action that will be undertaken at theBountiful/Woods Cross/5th South PCE Plume Site (OU1) under a ROD.

• A Remedial Investigation (RI) of OU1 completed in 2003 identified agroundwater contaminant plume consisting of dissolved phase chlorinatedhydrocarbons extending from the Hatchco property to the west-northwest.Importantly, this plume commingles with two other groundwater contaminantplumes (petroleum fuel and chlorinated hydrocarbon) originating from as yetunidentified sources remote from the Hatchco property.

Response - EPA agrees that the Hatchco groundwater plume commingles with agroundwater contaminant plume to the northwest (mainly MTBE); however, EPAhas not identified a secondary source west-northwest of the Hatchco property.Results of the remedial investigation for OU2 are inconclusive. The location ofsuspected secondary source, if exists, remains uncertain.

In addition to the source soils previously excavated by Hatchco at the Site, it ispossible that some source material for the Hatchco plume remains, limited to aninterval between one and three-feet thick occurring at a depth of approximately20-feet over a 0.5-acre area located on the central portion of the Hatchco property.This inferred source area is characterized by contaminant concentrations wellbelow the soil saturation limit (maximum TCE concentration of 91 milligrams perkilogram (mg/kg)) and the lack of observed dense non-aqueous phase liquid(DNAPL).

Response - It is not only possible that some source remains at the site, it isevident. Soil contamination is supported not only by the analytical data but alsoby the boring logs showing petroleum odor throughout the borings from 11 feet .down and by the free product observed at 20' bgs. As stated above, the maximumTCE concentration of 91 mg/kg is below the soil saturation limit, but theconcentrations are high when compared to the Dilution Attenuation Factor(DAF)of0.06mg/L (US EPA, Soil Screening Guidance, 1996; DAF value for a 0.5-acresite.). EPA believes the contaminated site may continue to present acontamination source to groundwater.

A Focused Feasibility Study (FFS) completed in July 2004 screened applicableremedial technologies and developed and evaluated remedial alternatives toaddress contaminated source soils and groundwater. Remedial alternatives to treatcontaminated soils were assembled from technologies retained after thetechnology screening step and included excavation, capping and soil vaporextraction, all of which were retained for the detailed analysis stage of the FFSexcept for excavation. Groundwater alternatives in the FFS included monitorednatural attenuation (MNA), enhanced in-situ biological treatment andgroundwater extraction with various above-ground treatment schemes, all ofwhich were retained for the detailed analysis stage of the FFS.

Response - The statement is consistent with the Final FFS report.

The Proposed Plan presents a summary of the RI and FFS and proposed apreferred alternative consisting of MNA (Alternative 2) coupled with enhancedin-situ biological remediation (Alternative 6). The Proposed Plan is unclear as towhat environmental media (soil, groundwater or both) would be treated under theenhanced in-situ biological remediation portion of the preferred remedy.

Response - The environmental media targeted for the selected alternative(Alternative 2 & 6) is the aquifer located under the Hatchco property. Thepreferred alternative will be effective in addressing the contaminants of concernin the saturated subsoil and in groundwater. The pilot study will be conducted toassess the best design to mitigate for groundwater contamination of the entireplume.

Hatchco is not willing to support any remedy that does not have a strong chance of beingtechnically effective. More specifically, while Hatchco continues to support Alternative 2(MNA) for the site, Hatchco has serious technical reservations and objections regardingthe additional remedy adopted in the Proposed Plan, Alternative 6 (enhanced in-situbioremediation). Hatchco's concerns regarding Alternative 6, as discussed more fully inthe general and specific comments, focus on three specific areas:

Response - EPA supports Alternative 2 (MNA) for the .ground-water downgradientof the Site and Alternative 6 (enhanced in-situ bioremediation) for source control.EPA has serious concerns with MNA as a stand-alone remedy. Hatchco has notadequately shown that MNA is an acceptable alternative for OU1. For EPA toconsider MNA as a stand-alone remedy, Hatchco must demonstrate that MNA willmeet the RAO's within a reasonable timeframe. Hatchco must demonstrate thisusing site-specific data or MNA cannot be selected as a remedy. Hatchcoprovides a minimal data set that does not meet the rigorous requirement todemonstrate that MNA will be an effective remedy for the OU1.

Hatchco performed the investigations for natural attenuation during the 2002investigations (RI, 2003). MNA was correctly described as the mitigating effect ofdispersion, dispersion, volatilization, sorption, abiotic degradation and biologicaldegradation. Hatchco indicated they had followed the EPA Technical Protocol far-Evaluating the Natural Attenuation of Chlorinated Solvents in Groundwater, September1998, (EPA 1998) to determine the applicabilitij of MNA to the site conditions.Hoioever, the field data presented in support of MNA by Hatchco are quite limited, andonly address EPA's "screening criteria" to determine if a full evaluation of MNA shouldbe implemented (EPA 1998). Hatchco places significant weight on biodegradation of thecontaminants for the remedy selection, but does tittle to support the biologicalmechanisms as directed in the EPA protocol (1998).

The full biogeochemical data set in support of MNA is summarized in Table 7-5 of the RIreport (2003). This table also shows the "points system" developed for EPA's screeningprocess in 1998. (Note that the National Research Council, shortly after the EPAprotocol publication, suggested this numeric ranking not be used to evaluate complexsites with intricate biological and hydrological circumstances. Rather, the proponent ofMNA should use the best available biochemical and geochemical understanding tosupport their case.) Hatchco evaluated the field screening data from three wells using the"points" evaluation system. The groundwaterfield data indicated "inadequate" to"limited evidence for anaerobic biodegradation of chlorinated solvents". Using the EPAscoring system this site has "limited evidence" for success of MNA to contain tltegroundwater contaminant plume. Therefore, a full-scale natural attenuation evaluationis likely not cost effective and this technology should not be considered further. However,if the proponent of MNA still wants to propose MNA, then a full natural attenuationevaluation should be completed to support the proposed MNA decision for the site. Whileconsiderable modeling was done to support MNA, no biogeochemical support for thisdecision was undertaken by Hatchco. In addition, only limited quarterly monitoring ofVOCs was performed during subsequent investigations to support this decision.

Therefore, only limited field evidence of reductive dechlorination, the primary attenuationmechanism, or contaminant mitigation exists far the site groundwater plume aspresented in the FFS (2004).

The Hatchco site-specific data do not support MNAfor containment of the groundwatercontaminant plume. Besides the minimal data set, a number of critical parameters werenever evaluated. For example, the site has never been sampled for methane, ethene, andethane. Methane is produced under highly anaerobic conditions, the same as thoserequired for reductive dechlorination. Ethene and ethane are end products of completedechlorination of the contaminants. Although Hatchco refers to non-toxic end productsresulting from the biological degradation of the contaminants, they offer no evidence thatthese compounds are produced at the site. The field data (Table 7-5) indicate aerobicconditions with elevated nitrate and.sulfate concentrations. The redox conditions arehigh and not conducive to reductive dechlorination. The TOC is very low and does notsupport reductive dechlorination. The only evidence of reductive dechlorination is thepresence ofds-DCE and VC. The biogeochemical evidence presented (Table 7-5) byHatchco in support of this remedy indicates an aerobic to nitrate reducing environmentNOT conducive to reductive dechlorination.

Groundwater analysis over the past four quarters was conducted to support the selectionof the MNA remedy. However, Hatchco focused only on VOC concentrations and did notinclude biogeochemical data to support the assumption ofbiodegradation. The data fromfour quarters (Figures 6-14 - 6-19) of groundwater sampling do not support a decreasingconcentration of total contaminants or even a decreasing trend in the more chlorinatedcompounds, indicating partial dechlorination. The plotted ratios of product/parentconcentrations likeivise do not support partial biodegradation but rather a stableconcentration or an increasing parent compound concentration.

Based on the Hatchco presentation of evidence to support MNA as the selected remedyfor groundwater treatment, there is inadequate support for biological degradation as amechanism for the biological reduction of contaminant concentrations in thegroundwater plume. In addition, there is no evidence (i.e., sufficient TOC), ifbiodegradation were occurring, that the rate could be maintained throughout thepredicted timeframe indicated by modeling.

EPA believes the preferred alternative (Alternative 2 & Alternative 6) providesthe best probability of success from the alternatives presented in the FFS. Thepreferred alternative is the most cost-effective and it will meet the site cleanupobjectives on a reasonable time. EPA's concerns regarding the implementationof MNA alone is presented in the responses to the general and specific comments.

1. The description of Alternative 6 in the Proposed Plan is internally inconsistentand includes enhanced in-situ bioremediation of the vadose zone, an alternativethat was specifically considered and properly eliminated as ineffective during thetechnology screening step of the FFS.

Response - Alternative 6 is consistent as presented in the FFS. The application ofAlternative 6 is not intended to treat the vadose zone contamination. Alternative6 is designed to treat VOCs in the contaminated aquifer (both, in the saturatedsubsoil and groundwater). Alternative 6 will enhance and accelerate thedegradation rate of VOCs emanating from the source, the Hatchco property.

2. Alternative 6 is not justified without first collecting the data necessary to evaluatethe effectiveness of MNA.

During the remedial investigation, Hatchco collected data to evaluate whetherMNA was taking place at OUl according to the EPA's Technical Protocol forEvaluating Natural Attenuation of Chlorinated Solvents in Groundwater. Theresults were scored and compared according to a point system to determine ifconditions exist to support MNA (via biodegradation) by a reductivedechlorination process. The score then was compared to an interpretationcriterion that ranges from inadequate - limited - adequate, to strong evidence ofanaerobic biodegradation. The OUl specific data results indicated MNA viaanaerobic biodegratation is inadequate to limited.

EPA is concerned that the groundwater plume emanating from the Hatchcoproperty, whether commingled or not, extends approximately 2500 feet westnorthwest of the Hatchco property boundary line and that contaminatedgroundwater plume is within 500 feet of several domestic wells. Furthermore,OU2 data show a potential increase ofTCE contamination at a domestic welllocated within 500 feet of the western edge of the plume boundary line. It will notbe prudent for EPA to wait and collect data for years to evaluate theeffectiveness of MNA.

3. The potential exists for Alternative 6 to result in short-term risks that are greaterthan any current risk associated with the Site. Such short-term risks coupled withthe potential need for repeated treatments under Alternative 6 will hinderredevelopment of the Hatchco property.

Response — This statement is inconsistent with the information presented to EPA.According to the Final Focused Feasibility Study Report, the Short-TermEffectiveness evaluation states, "No Short-term risks to workers, the community,or the environment are posed under this alternative. Protection will be achievedupon implementation of the 1C restricting groundwater use. " The short-termrisks as presented in the final FS report posed no concern at the time riskassessment and the final FFS were released.

EPA believes site redevelopment will improve the implementation of the preferredalternative, paving the site will reduce infiltration; therefore, reducing thecontaminant loading to be mitigated by MNA once the active remediation iscompleted. EPA will work with Hatchco to plan and minimize interfering with thedevelopment of the area.

In light of Hatchco's limited resources, it makes no sense to spend additional moneybased on an extremely low probability of success. Hatchco proposes that Alternative 6not be pursued at this time. Instead, Hatchco believes that current information supportsselection of Alternative 2. Alternative 2 will allow the effectiveness of MNA to beassessed through scheduled groundwater monitoring. EPA will have an opportunity toconsider, as part of the statutory five-year review process, whether natural attenuation isor is not occurring and, if not, whether other alternatives should be considered. Existingdata suggests that natural attenuation is in fact occurring and the existing data areconsistent with the conditions predicted by groundwater modeling.

EPA is aware of Hatchco's limited resources and has considered and securedfunding for taking the lead for the RD/RAfor OU1. EPA will evaluate the remedyannually and at the end of the statutory five-year review will make adetermination on the effectiveness of the Preferred Alternative.

Hatchco has not adequately shown MNA as an acceptable alternative nor havethey developed a meaningful mass term for contamination entering thegroundwater from residual soil sources. Until this is done, the soil source mustbe considered to continually contribute to the groundwater plume. In the finalanalysis, Hatchco will need to demonstrate that MNA will meet the RAO'sfor theentire TCEplume within a reasonable timeframe. Hatchco will need todemonstrate MNA using site-specific field data or MNA cannot be selected as astand-alone remedy.

EPA believes the Preferred Alternative has a high probability of success for thefollowing reasons:

The use of enhanced in-situ bioremediation of chlorinated solvent is a very wellknown and field proven technology. The field data from the Hatchco site,although minimal, indicate that conditions at Hatchco can be enhanced to rapidlyremove contaminant mass from the groundwater plume. Elevated concentrationsof VC are indicative of reductive dechlorination processes occurring in the sub-surface. Although, the biogeochemical data do not support the assumption ofconditions conducive to active reductive dechlorination, the conditions can bemodified by addition of an electron donor to cause the rapid and completeremoval of contaminant mass. The success of this technology depends upon thepresence of a biological community that can reductively dechlorinate thecontaminants to non-toxic compounds, i.e. - ethene and ethane, and an adequatesupply of organic materials that can serve as the electron donor. The presence ofthe microbial community can be confirmed both by groundwater chemistry and byDNA analysis. The presence of adequate electron donor (organic compound) isassured by adding the required amount to stimulate the biological reactions.Proof of process is determined by monitoring the biogeochemistry and the mass ofcontaminant to show mass is removed and optimal conditions are maintained.

EPA proposed combining Alternative 6, enhanced in-situ bioremediation forsource control with MNAfor the downgradient plume. Hatchco has notconducted an adequate groundwater investigation to determine the conditionsdowngradient relative to reductive dechlorination. However, if sourceconcentrations are reduced to low levels, then the dispersion and dilution thatoccur naturally will mitigate the concentration of the contaminants in thedowngradient plume. If biological degradation is active, the plume will berapidly reduced and MNA becomes a very effective tool for remediation of thegroundwater plume. EPA has proposed a pilot study and field investigation toconfirm the conditions under which the MNA scenario will be obtained.

EPA has also considered the potential application of enhanced in-situbioremediation at the suspected secondary source. Enhance anaerobicbiodegradation (EAB) combined with MNA can be an effective tool for largeplumes by installing treatment cells at "hot spots " throughout the plume,especially where another source may enter the initial plume. This approachincorporates MNA to a significant, yet appropriate extent, and we believe theapproach has a high probability of success and the active remediation will likelybe complete within a reasonable time.

EPA accepts the determination that the degradation TCE in the aquifer suggestssome evidence that MNA is occurring at OU1, although the elevated vinylchloride concentrations suggest the degradation is or was incomplete. EPA alsorecognizes the plume may be commingled with an alleged, suspected secondarysource in the vicinity of Jensen Automobile Shop. However, the fact that EPA didnot detect high concentrations of VOC in soils at the suspected secondary sourcemakes the Hatchco modeling inconclusive. EPA collected 25 vadose zone soilsamples around the perimeter of the suspected secondary source (CDM RI, 2004).The sample results detected TCE in only one soil sample, at a concentration ofonly 0.9 ug/kg (CDM-RI, Figure 4-10). When comparing this single detection tothe higher TCE concentration in the Hatchco vadose zone soil sample result of90,000 ug/L, it seems unlikely that a substantial secondary source of TCE existsdowngradient from the Hatchco property.

Hatchco's modeling did not include this suspected source in the evaluation of theentire TCE plume. Uncertainties with the groundwater fate and transportmodeling still exist. Hatchco's modeling did not include an evaluation of apotential release during and after the air sparging pilot test. Since a work planand the pilot test results report was not submitted for EPA 's review, EPA did notevaluate the effectiveness of the pilot test.

Since EPA did not detect high concentrations of TCE in the vadose zone soil inthe vicinity of the suspected secondary source, it plausible that the lowgroundwater concentrations immediately upgradient of the postulated secondarysource are due to mass removal during the air sparge pilot test. Alternately,

intermittent early spills from Hatchco may explain the elevated TCEconcentrations in groundwater in the vicinity of the Jensen Automobile shop.

EPA is concerned that the conclusions of the Hatchco model may not reflect thetrue nature and extend of the TCE groundwater plume. Due to this concern andthe fact the contaminated groundwater plume originating from Hatchco is within500 feet of a municipal well, several domestic wells, and coupled with thepotential expansion of the plume, EPA sees a need to take an active responseaction rather than to wait and see whether or not MNA alone is an appropriateremedy for OU1.

General Comments on Proposed Plan

1. The Proposed Plan is Internally Inconsistent and Inconsistent with the FFS

In different parts of the Proposed Plan, Alternative 6 is described as treatment ofvadose zone soils only, treatment of groundwater only and treatment of bothvadose zone soils and groundwater. The Proposed Plan is therefore internallyinconsistent; it is entirely unclear whether the Proposed Plan is attempting toadopt the Alternative 6 as presented in the FFS or whether EPA is intending tomodify the alternative described in the FFS. This is a critical distinction becausetreatment of vadose zone soils by enhanced in-situ bioremediation was eliminatedat the remedial technology screening stage of the FFS. Specific examples ofconfusing inconsistencies between the FFS and the Proposed Plan include thefollowing:

Response — Alternative 6 is intended for the portion of the shallow aquifer locatedunder and donwgradient of the Hatchco property. It is anticipated thatAlternative 6 will be effective degrading TCE in saturated subsoils andgroundwater. Pending on the pilot study and the technology application resultsat Hatchco, EPA is considering implementing the preferred alternative at thesuspected secondary source located downgradient of the Hatchco property.

The description of the Preferred Alternative is inconsistent with the CleanupObjectives discussed on Pg. 4 that include the following statement:

"EPA believes that treating subsurface soils at the source to remove highlevels of VOCs, coupled with monitored natural attenuation willpermanently reduce the toxicity, mobility, and volume of thosecontaminants that constitute a threat at the Site. Once contaminants aretreated from the subsurface soil, EPA believes that over time naturalprocesses will cleanse groundwater. "

Response — The Proposed Plan is not a technical document. The Proposed Plan isintended for the public use. Within the definition of sub-soils is included soilunder the surface, soil in the vadose zone, soil in the saturated zone, or soil in the

aquifer formation. The Proposed Plan is not inconsistent with the FFS. EPAacknowledges that as written, the interpretation of the proposed plan may appearinconsistent with the FFS; however, via the responses to these comments EPA willattempt to clarify the intent of the Preferred Alternative as described in theProposed Plan.

From this discussion, it appears that EPA proposes to treat vadose zone soils onlyand permit contaminants in the saturated zone to attenuate naturally. However,Alternative 6 is described on Pg. 5 as:

"the injection of a substance into the aquifer to speed up the breakdown ofthe plume downgradient of the source. "

Response — The statement is valid as written.

From this statement, it appears that EPA has selected direct treatment of theaquifer without treatment of the vadose zone. This is how Alternative 6 isdescribed in the FFS. However, in the Summary of the Preferred Alternative EPAstates:

"This combination of alternatives [2 and 6] would achieve cleanupobjectives by increasing the breakdown rate ofVOCs in sub-soils andgroundwater trough treatment."

Response/clarification - "This combination of alternatives [2 and 6] wouldachieve cleanup objectives by increasing the breakdown rate ofVOCs in theaquifer (saturated sub-soils and groundwater) through treatment (In-SituBiological/Chemical Remediation)."

Here EPA seems to be describing treatment of both the vadose zone and theaquifer. These inconsistencies were perpetuated at the public meeting where EPAstated that Alternative 6 consisted of aquifer treatment alone (August 24, 2004Public Meeting Minutes, Pg. 14, lines 21 through 24).

Response — The statement is valid as written in the Public Meeting Minutes andclarified the intent of Alternative 6 at the public meeting. Alternative 6 consists ofaquifer treatment alone. "

Hatchco notes EPA's apparent confusion regarding distinct differences ineffectiveness and implementability of in-situ biological treatment between thevadose and saturated zones. In fact, the option to treat the vadose zone using anin-situ biological method was eliminated early in the FFS process (Table 6-1,FFS, 2004).

Response - As stated in the Public Meeting Minutes, the intent of Alternative 6 isto treat the contaminated aquifer.

Elimination of in-situ biological/chemical remediation of the vadose zone resultedfrom low implementability and a limited record of successful applications of thetechnology at full-scale. The Denver representative for Regenesis (the HRC®vendor) reviewed the Site data and concluded that the Site is not a strongcandidate for vadose zone treatment with HRC®. Correspondence from Mr.Herrington on this subject is provided as Exhibit A.

Response - Alternative 6 is not intended for the vadose zone.

More specifically, Hatchco notes the following factors limiting the effectivenessof an in-situ bioremediation of the vadose zone:

1. Limited free water in the vadose zone. Biological reactions occurwhere contaminants may freely dissolve into solution;

2. Difficulty in maintaining anaerobic conditions in the vadose zone;3. Heterogeneity, stratification and high clay content of vadose zone soils

limiting the ability to deliver HRC to target horizons; and4. Association of TCE with free-phase petroleum hydrocarbon

exacerbating the adverse effects of limited free water and geologicheterogeneity (the highest concentration of TCE in the vadose zonewas found hi association with free-phase petroleum hydrocarbons). Inorder to degrade the target contaminant, the free-phase hydrocarbonsmust dissolve into limited soil moisture. This is unlikely to occur inthe time frame associated with a single or even multiple applicationsof HRC®

Response - Alternative 6 is not intended for the vadose zone..

hi addition to these general and site-specific technical practicability issues,consideration should also be given to the low potency of the inferred source area.The source area described in the RI and FFS Reports is characterized by a layer ofimpacted soils between one and three-feet thick spread over a 0.5-acre area withan average TCE concentration of 29.78 mg/kg (direct push sample stations 64,207, 82 and 41). This concentration represents less than 14% of the calculatedsoil saturation limit for TCE (RI Report, pg 6-25). Even the maximum TCEconcentration measured anywhere on the site (91 mg/Kg) is well below thecalculated soil saturation limit.

Response - Application of alternative 6 is not intended for the vadose zone. ThePreferred Alternative has considered the low potency of the contaminated vadosezone area. This is one of the factors that favor the application of Alternative 6 tothe aquifer in the source area.

Soil contamination is elevated within the "hot spots" indicated above. The concentration(91 mg/kg) is well below the "saturation" concentration as shown by Hatchco but is well

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above the DAF of 0.06 mg/kg set by EPA. It is not dear how Hatchco determines theinfiltration rate of contamination into the groundwater to indicate that these soilconcentrations are not a problem resulting in continued groundwater contamination.

However, groundwater contamination below the apparent soil source area is relativelyloiv, given the soil contamination. In addition, contaminant distribution within thegroundwater indicates at least historical biological degradation. The rate of thisbiodegradation has not been clearly defined and therefore cannot be used to support thatintrinsic biodegradation of the contaminants will contain the groundwater plume in thefuture. It is clear tiwt a faster remediation rate in the groundwater, as proposed by EPA,would decrease the concentration entering the plume outside the source area andtherefore be more amendable to MNA. Thus, the most cost effective approach to meetingremediation objectives is believed to be Alternative 6, as described in EPA's ProposedPlan, utilizing enhanced anaerobic bioremediation for high concentration source areas,and MNA for the remainder oftlie plume.

Active in-situ biological treatment of the vadose zone does not make sense inlight of the low-level and diffuse nature of the inferred source area coupled withthe general and site-specific implementability issues described above.

Response - Application of alternative 6 is not intended for the vadose zone.

Although direct aquifer treatment was retained in the FFS as Alternative 6, itrequired multiple treatments of the aquifer in order to degrade dissolvedcontaminants as they are introduced to the aquifer from the inferred low-gradesource in the vadose zone. Direct treatment of the vadose zone was determined tohave a low probability of success and was eliminated as an'option as discussedabove. The number of treatments necessary to treat the aquifer under Alternative6 can be estimated by consideration of the following:

Response - Application of Alternative 6 is not intended for the vadose zone.Alternative 6 was evaluated by the FFS report.

• The HRC® product has an effective residence time of 18-months(according to Regenesis promotional literature). A relatively newproduct, HRC-X*^, reportedly has an expected effective residence timeof3-years.

• The duration of the source term in contaminant transport modeling inthe remedial investigation ranged from 10 to 40 years.

Assuming HRC-X® is used, between 3 and 13 treatments would be necessary tocontinuously degrade contaminants in the aquifer as they were introduced fromthe overlying vadose zone. The FFS assumed five treatments when developingthe $328,800 present value for Alternative 6. The actual cost may be many timeshigher. Given the technical impracticability of in-situ biological treatment of

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vadose zone and the complexity and cost of between 3. and 13 aquifer treatmentevents, Alternative 6 is not likely to be effective.

Response - This information is not consistent with the final FFS report. Theinformation on the number of treatments necessary to treat the aquifer waspresented to EPA in the final FFS report. The FFS report states, "Based onmanufacture recommendations (HRC^1), an initial treatment would be followed byadditional treatments every two years using no more than 50% of the previouschemical dose. Based on this rule of thumb, a total of four treatments over acourse of 10 years is assumed. . . The actual frequency and magnitude oftreatment would depend on the groundwater quality monitoring data. " (FFS July2004, Alternative 6, Page 8-12)

Please note that the Proposed Plan did not endorse a vendor product, but it describes apropose technology "In-situ Biological/Chemical Remediation with InstitutionalControls." The Proposed Plan describes a reduction of contaminant concentrations inthe source area (not the vadose zone) with potential implementation ofMNAdowngradient from the source. EPA does not specify the mechanism(s) of naturalattenuation in the downgradient plume but emphasizes reduction of the source areaconcentration is necessary to allow MNA processes to mitigate contaminantconcentrations in the downgradient plume.

2. Inadequate Justification for Active Treatment

EPA's selection of Alternative 6 is premature for the following reasons:

• Insufficient groundwater monitoring data has been collected tosubstantiate EPA's primary justification for active remediation (the lack ofdeclining contaminant concentration trends).

• Observed concentration trends over the monitoring period (4 quarters) areconsistent with contaminant fate and transport modeling. Modelingpredicts declining tends over a longer monitoring period.

Response - These two bullets contradict each other. The first bullet makesthe point that four quarters of data are insufficient to justify activeremediation. The second bullet suggests that four quarters of data aresufficient to validate a fate and transport model that predicts trends over alonger monitoring period.

EPA believes the groundwater monitoring data is insufficient to supportHatchco 's modeling and MNA alone. See the discussion of inadequateevidence to support Alternative 2 in the following comments:

• Alternative 2 is protective of human health and the environment byminimizing the likelihood of human exposure to contaminatedgroundwater through the use of ICs.

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Response - EPA is concerned that contaminated groundwater emanatingfrom Hatchco and the suspected secondary source may continue todegrade groundwater resources. EPA and UDEQ have not made adetermination that a secondary source exists downgradient from theHatchco property. EPA is concerned that the secondary source has notbeen defined and the possibility still exists that the high levels ofTCEcontamination are due to earlier releases at the Hatchco property. EPAis concerned that a MNA remedy alone will allow groundwater tocontaminate several domestic wells. ICs will not protect these wells frompotential groundwater contamination.

• Monitored natural attenuation without active remediation has beenimplemented at other sites in Region 8 and is appropriate under applicableguidance.

The implementation of MNA at another site has little to do with theacceptance of the remedy at this site

Hatchco believes that the remedial method proposed in Alternative 6 is ofquestionable efficacy, will interfere with site redevelopment and will not increasethe protectiveness of the remedy (See below and General Comment No. 3).Accordingly, Hatchco believes that Alternative 2 should be allowed todemonstrate its effectiveness before EPA determines that other alternatives shouldbe considered.

EPA has repeatedly expressed concern over the lack of decreasing contaminantconcentration trends in groundwater quality. This is discussed on Pg. 7 of theProposed Plan where EPA states that:

"Source remediation is needed at this Site because the evidence of naturalattenuation in the groundwater at the Site is limited. No significant decrease ingroundwater concentrations over time is evident in any well...."

Response - There is inadequate evidence to justify selection of Alternative 2,Monitored Natural Attenuation (MNA), as a stand-alone remedy at the Hatchcosite for the following reasons:

• There is insufficient groundwater monitoring data to support thecontention MNA is active and currently mitigating the contaminantgroundwater plume.

• The observed concentration trends over the monitoring period (4 quartersdo not show a decreasing trend and therefore do not support MNA.Additionally, Hatchco has not included any effort using historic data tosupport the MNA remedy. EPA cannot accept the modeling predictionsbased on the available data to support a MNA remedy.

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• Alternative 2, MNA, has not been proven and Hatchco has not attemptedto support MNA as a stand-alone remedy with field data. Table 7.5 in theRI does not support MNA and does not support intrinsic biodegradation ofthe chlorinated solvents at.the site. Therefore, EPA cannot accept MNAas a remedy that is protective of human health and the environment evenwith ICs.

• The implementation of MNA at another site has little to do with theacceptance of the remedy at this site.

• EPA has addressed the question of the efficacy of the proposed plan. Thetechnology has been proven and site data justify the use of this technologyat Hatchco. Site data show that reductive dechlorination at least to VChas previously occurred at the site, which is sufficient to determine thatthe process can be stimulated. These data are not sufficient, however, todetermine that the process is presently occurring, nor that it will continueoccur until the cleanup objectives are met, which would be required toselect MNA.

• Source remediation is part of the selection of MNA as a remedy (OSWERDirective 9200.4-1 IP). Therefore, Hatchco must address this aspect ofthe remedy. Hatchco has not demonstrated MNA processes can effectivelymitigate the ground-water plume with or without source input. Hatchcohas not adequately demonstrated the efficacy of MNA at the site.

It is clear from this summary that EPA would consider source remediationunnecessary if there was stronger evidence for natural attenuation at the Siteand/or if their was evidence for significant deceases in contaminantconcentrations. Hatchco believes that there is more than sufficient evidence tosupport the selection of Alternative 2 as a stand-alone remedy at the Site,including the following:

Evidence of Natural Attenuation

Hatchco believes that EPA has overlooked the following compelling evidence ofnatural attenuation:

• Decay products have consistently been observed in groundwater.

Sorption, diffusion, dispersion and volatilization (partitioning fromgroundwater to soil gas) are also attenuation mechanisms (Pg. 15,OSWER Directive 9200.4-17P) that are occurring at the Site.The calibrated model incorporates contaminant degradation ratesreflecting in-situ biological transformation of Site contaminants. The

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observed groundwater quality trends during the four quarters ofmonitoring are predicted by the model.

Response - EPA considered this evidence for the selection of the PreferredAlternative.

Declining Contaminant Concentration Trends

EPA bases its conclusion regarding concentration trends on only four, quarters ofgroundwater quality data. The lack of obvious declining contaminantconcentration trends over the monitoring period is predicted by the contaminanttransport model developed during the RI. Model output illustrating the predictedcontaminant concentration trends at various monitoring wells across a single yearis provided as Exhibit B. A review of the plots shows them to be similar to timevs. concentration plots based on groundwater quality monitoring data presented asFigures 6-14 through 6-19 of the RI Report.

Response — EPA based its conclusion on the nature and extent of the TCEgroundwater plume emanating from the Hatchco property and extending west andwithin 500 feet of several domestic wells.

Although not included in the RI Report or the plots in Exhibit B, considerablegroundwater monitoring data was collected by EPA in 2000 that indicatesdeclining concentration trends over time. Hatchco objects to EPA's proposal toinitiate active remediation prior to collecting sufficient data to evaluate time vs.concentration trends. A groundwater monitoring plan implemented as part ofAlternative 2 would ensure the collection of such data. Should the data show thatconditions at the Site are worsening or deviating from model predicted trends,other alternatives could be considered during the statutory five-year remedyreview process.

Response — The data presented in the RI/FS is insufficient to support MNA as astand-alone remedy. Hatchco has not presented adequate evidence in support ofMNA for the following reasons:

• There is little to no evidence to support declining concentrations based onthe data submitted by Hatchco. The rate of biodegradation is mostimportant in demonstrating MNA will meet RAOs in a reasonabletimeframe.

• There is no supporting evidence for the primary mechanism forcontaminant degradation (biodegradation). Evidence presented byHatchco is preliminary, contradictory, and inadequate to supportselection of MNA as the groundwater remedy.

• Intermediate decay products are present, but Hatchco has notdemonstrated detoxification has occurred.

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Aattenuation mechanisms are always included in all MNA evaluations. IfHatchco contends one of the non-destructive mechanisms is moreimportant than biodegradation in mitigating concentrations then theassumption should be supported with field data.The use of a model as the primary support for selection of MNA is not inkeeping with OSWER Directive 9200.4-1 IP. EPA has previously notedthe inadequacy of the input to this model for predictive purposes,especially the representation of site hydrogeology, the basis forbiodegradation rates, the source term, and the calibration approach. Inparticular, the modeling is inadequate for the following reasons:Conceptual Model and Hydrogeologic System Assumptions - The conceptualmodel used at Hatclico uses a single homogeneous aquifer system with tiuodimensions having isotropic properties across a 60-ft thick vertical interval. Thesystem used in the model does not resemble the complex hydrogeological systemat the site which is comprised of multiple layers of different types of soil typesincluding sand, silt, clay, and gravel. Based on the cross-section, it would beexpected that most oftliefloiv is occurring in the sand zone which is 10- to 15-ftthick and starts at about 20ft below ground surface. Slug testing showedvariability of hydraulic conductivity of at least 1.5 orders of magnitude,reflecting to some extent (probably significantly underestimating) theheterogeneity of the different soil types. In the numerical model, a singlehydraulic conductivity value based on the geometric mean of the three slug testvalues was applied to tlie entire 60-ft thickness across the whole domain,furthermore, porosity and specific yield were never measured at the site, butwere input in the model as single numbers based on the geometric means ofliterature values for three of the soil types - sand, silt, and clay. Groundwaterflow and contaminant transport do not occur uniformly in different.hydrostratigraphic units based on some average of the properties in those units.They occur based on the unique, site-specific properties of the units. While arepresentation such as this might suffice for a high-level screening of what flowand transport might be like at the site, it is wholly inadequate for use inpredictive modeling upon which remedy selection can be based.

Biodegradation Rates Assumptions - The degradation rate is a critical parameterfor natural attenuation modeling because of the high degree of sensitivity of themodel output to the parameter. Initial estimates of degradation rate forchlorinated ethene constituents were obtained both from literature values andfrom the Buscheck and Alcantar (1995) method built into the Biochlor model.The initial rates were tiien used for model calibration and were changed in orderto provide the best fit betiueen the model and the field data.

In general, the approaches used to estimate degradation rate are appropriate forhigh-level screening, but are inappropriate for predictive modeling and remedyselection due to several shortcomings. Literature values, by definition, are notsite-specific. Wliile it is useful to understand the range of degradation rates atother sites for screening, they could be under entirely different conditions than a

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site of interest. For example, several aerobic sites exist where little or no evidenceof reductive dechlorination exists; it would be completely inappropriate to useliterature values for predictive modeling at such a site.

The Busclteck and Alcantar method for estimating degradation rates hassignificant problems for use in long-term prediction of natural attenuation rates.These issues are discussed in detail in Sorenson et al. (2000), where it is pointedout that the relationship ofdispersivity and the biological degradation rate iscounterintuitive because of the use of the one-dimensional advection dispersionequation. As dispersivity is increased, the biological degradation rate estimateactually increases for a given data set. In fact, in cases where the effect ofsorption is not large, tlie Buscheck and Alcantar method will actually yield abiological degradation rate that is greater than the gross degradation rate whichincludes dilution, dispersion, sorption,.and degradation obtained directlythrough graphical extraction (Sorenson et al., 2000). In other words it gives abiological degradation rate that is greater than the actual degradation rate due toall natural attenuation processes combined. Even if the method were appropriate,it relies on the assumption that all wells are on the samefloiv path, which is adifficult assumption to support for MW-2S-at least, because it appears to becompleted in a completely different hydrostratigraphic unit than thedoiungradient wells.

While this is problematic enough, a further problem exists when using ratescalculated in this way for predictive modeling. Because the calculated rateactually (inadvertently) includes dispersion effects, it is a poor predictor of futureconcentration trends. As shown in Sorenson (2000), the rate at which dispersioncontributes to decreasing concentrations over time is a function of concentrationgradients. Concentration gradients in a plume ivhose source is removed decreaseover time, thereby causing t/ie rate of contaminant decrease over time to decreaseas well. Therefore, degradation rates which include dispersion can overestimatelong-term contaminant degradation rates by as much as a factor of 7. Clearly,rates calculated using literature values or the Buscheck and Alcantar method areinappropriate for predictive modeling and remedy selection.

As stated in these responses there are many uncertainties associated with the informationpresented the RI/FS. EPA cannot accept MNA as a stand-alone remedy for the site.During the remedial design, EPA will conduct additional groundwater analysis tosupport efficient stimulation of biodegradation at the site and to determine the location ofthe treatment system. In addition, EPA will collect data to understand the naturalattenuation factors that effect the contaminant concentrations in the plume.

No Net Benefit

Given the availability of municipal drinking water and the implementation ofinstitutional controls on groundwater use at the Site, no reduction in the level ofprotection of human health and the environment would occur if Alternative 2 is

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adopted as a stand-alone remedy, particularly in light of EPA's ability to considerother options during the five-year review process. It is also important to note thatthe acceleration of the natural contaminant degradation process under Alternative6 is expected to accelerate the production of vinyl chloride, potentially increasingshort-term risks. This is discussed further in General Comment No 3.

Response - EPA understands the biodegradation mechanisms associated withenhanced in-situ bioremediation. EPA will assure that no VC accumulates duringthe implementation of this technology. There are a number of means to mitigatesuch occurrence. Primary is the understanding that VC is an intermediate andethenet'ethane presence must be demonstrated as part of either an MNA remedy oran EAB remedy. No additional short-term risk will result from EABimplementation.

Not only will adopting Alternative 2 as a stand-alone remedy maintainprotectiveness and provide consistency with EPA's policy of collecting adequatedata to support remedy decisions, it also is consistent with recent remedydecisions for NPL Sites in the Salt Lake Valley. There are other nearby siteswhere source removal/treatment was not required, but an MNA remedy wasinstead selected in spite of the fact that the contaminants are inorganic (arsenic,cadmium, etc.) and do not degrade over any time frame..

Response - MNA as a remedy must be supported by site-specific data, not the factit was accepted at other locations. Undoubtedly more expensive remediationstrategies such as long-term pump-and-treat, have been implemented at othernearby sites, but that does not make them more appropriate for this site either.

3. Alternative 6 will Discourage Productive Re-Use of the Site and May IncreaseShort-Term Risks

Productive re-use of the Site should be an important consideration. From aredevelopment standpoint, Alternative 2 as a stand-alone remedy is superior to theProposed Plan. Alternative 2 does not require extensive remedial constructionwhile future Site redevelopment would likely be hampered under Alternative 6.At a minimum, several years would be required to design, implement, and analyzedata from the pilot study considered in the Proposed Plan. For similar reasons,other alternatives, such as Alternative 4 (Soil Vapor Extraction), would have anegative impact on future reuse of the Site.

EPA should be aware that future Site use remains uncertain due to the fact that theUtah Transit Authority (UTA) has identified the Site as the preferred location ofone of eight new stops (which would also include parking) for its SaltLake/Weber County Commuter Rail project, a high-profile regional transportationinfrastructure project. While UTA has not yet attempted to purchase or condemnthe Site, construction of the commuter rail project is currently scheduled to beginin 2005, with the commuter rail segment opening in late 2007. In any event,

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Alternative 2, as a stand-alone remedy, will not only be adequately protective ofhuman health and the environment but would be the remedial alternative mostconsistent with Site redevelopment.

In addition, a potential increase in short-term risks under Alternative 6 may alsoadversely impact the ability to put the Site into productive reuse. Production ofvinyl chloride is accelerated under Alternative 6 as compared with productionrates under Alternative 2 alone. This effect has been documented by the HRC®vendor, Regenesis, at many sites (case studies are available on their websitewww.Regenesis.com). Vinyl chloride is more mobile in soil vapor and has ahigher Henry's Law constant than either of the parent compounds (TCE and cis-1,2 DCE). It is also more than twice as carcinogenic as TCE via the inhalationpathway (inhalation SFTCE = 0.006 (mg/kg-day) "'; SFvc = 0.015 (mg/kg-day) "').These two effects may combine to create short-term risks exceeding current risks.In addition to being one of the nine NCP criteria, this potential short-term riskwould further discourage development and productive reuse of the Site.

In sum, adopting Alternative 2 as a stand-alone remedy at this juncture wouldfacilitate Site redevelopment while avoiding potentially significant short-termrisks.

Response - As noted in our detailed review and recommendations, we believe siteredevelopment might actually improve the implementation of the preferredalternative, because paving over much of the site will reduce infiltration, therebyreducing the contaminant loading to be mitigated by MNA once activeremediation is complete.

Response - No additional risk is anticipated with the application of preferredalternative. The Final Focused Feasibility Study Report states, "No Short-termrisks to workers, the community, or the environment are posed under thisalternative (Alternative 6). Protection will be achieved upon implementation ofthe 1C restricting groundwater use. " The short-term risks as presented in thefinal FFS report posed no concern at the time risk assessment and the final FFSwere released.

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Specific Comments:

1. Pg. 3, right column, 2nd para. - EPA describes subsurface soil contaminationlevels as high. The maximum TCE concentration measured in any soil samplewas 91 mg/kg or roughly one-half the soil saturation limit. This does notconstitute "high levels of VOC's." As discussed in the Final RI Report, theresidual contamination in the vadose zone is not concentrated. The inferred sourcearea consists of a layer of impacted soils between one- and three-feet thick spreadover a 0.5 acre area with a low average TCE concentration of 29.78 mg/kg .

Response - EPA's description of the soil contamination as high is supported notonly by the analytical data but also by the boring logs showing petroleum odorthroughout the boring from 11 feet down and by the visible free product oozingfrom the sand/silt layer at 20' bgs. However, it is not clear whether the soilcontamination will provide enough contaminant flux to groundwater once thehigh concentration in the aquifer areas are remediated. It is thought that oncehigh groundwater concentrations are cleaned up, MNA will be sufficient tocontrol any residual flux from the unsaturated zone soils. However, a realisticand rational approach to estimating the input to the groundwater can bedeveloped. Hatchco has not done this estimation to determine whether MNAbiodegradation processes (if occurring) can remove the estimated amountentering the groundwater with time.

2. Pg. 4, left column, 1st para. - The text states that the proposed action will be thefirst remedial action taken at the Site. Since 1995 Hatchco has taken manyremedial actions including source removal and active groundwater treatment,including:

• Removal of an oil/water separator.• Excavation and on-site treatment of contaminated gravel and native soils

from a french drain.• Removal of waste oil UST and remediation of contaminated soils

surrounding the UST.• Installation (in 1998) and operation of a five-well, low-volume air

sparging system to treat contaminated groundwater.

Hatchco has expended approximately $600,000.00 to date on investigative andremedial measures.

Response - EPA acknowledges and has taken into consideration that Hatchco hastaken several actions to cleanup contaminants at the Site. However, consistentwith the NCP Section 300.435, ". . .RD/RA activities shall be in conformance withthe remedy selected and set for in the ROD or other decision document for thesite. This is the first ROD and therefore the first remedial action taken at theBountiful Woods/Cross 5th South PCE Plume NPL Site.

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3. Pg. 4, left column, 2nd para., 1st sent. - Subsurface soil concentrations are nothigh (See Specific Comment No. 1).

Response - See response to Comment 1

4. Pg. 4, left column, 2nd para., last sent. - Treatment of subsurface soils by in-situbiological methods was eliminated during the technology screening step of theFFS (See General Comment No. 1).

Response - The comment is consistent with the FFS report.

Also, EPA explains that once contaminants are treated from the subsurface soil,natural processes will cleanse groundwater over time. It is also true that thenatural processes will cleanse the groundwater to MCLs even if contaminants insubsurface soils are not actively remediated.

Response - Alternative 6 will be applied to the aquifer zone area only.It is not clear whether the soil contamination will provide enough contaminantflux to groundwater once the high concentration in the aquifer areas are .remediated. It is thought that once high groundwater concentrations are cleanedup, MNA will be sufficient to control any residual flux from the unsaturated zonesoils.

5. Pg. 5, left column, 1st para. - The text describes.injecting a substance into theaquifer to speed up breakdown of VOC's. It is not clear whether EPA isproposing vadose or saturated zone treatment or both (See General Comment No.1 and Specific Comment No. 4).

Response - The paragraph states, ". . a substance will be injected into theaquifer to stimulate bacteria activity.. .The overall purpose of this alternativewould be to stimulate the breakdown of VOCs at the source, to speed up thebreakdown of the plume downgradient from the source, ..." The reference to thesource, is the contaminated source area in the aquifer located directly under theHatchco property. Alternative 6 does not include treatment of the vadose zone.

6. Pg. 5, right column, last para. - The text states that with the exception ofAlternatives 2, 3 and 7c, all groundwater alternatives would eliminate humanexposure risks from direct contact with contaminated groundwater throughtreatment. However, Alternative 7c also involves groundwater treatment at thePOTW as stated under the description of Alternative 7c.

Response — EPA recognizes this difference between the alternatives.

7. Pg. 6, left column, 1st para. - EPA describes the potential effects of a fluctuatingwater table on groundwater quality only in the discussion of Alternative 3.Because this effect may occur under all alternatives, the justification for

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elimination of the capping remedy is premature. Capping, including barriers thatmay be installed in connection with Site redevelopment, may prove to be aneffective remedy if coupled with Alternative 2.

The FFS identified several benefits associated with capping. These includeacceleration of groundwater restoration by reducing the amount of infiltratingprecipitation and associated leaching of contaminants from the vadose zone to thewater table (Pg 8-7, FFS, 2004). Contaminant mass retained in the vadose zonewould degrade naturally.

Response - EPA supports this action. IfHatchco wishes, EPA would not opposea cap to redevelop the Site.

8. Pg. 6, left column, 4th para. - Maintenance problems are identified as a reasonwhy pump and treat technologies may be unreliable. Although pump and treatsystems are maintenance intensive, they are effective if hydraulic capture isestablished. The FFS identified the difficulty in establishing hydraulic capturewhile not adversely impacting third party contaminant plumes as the primaryissue related to effectiveness and implementability.

The text goes on to state that Alternatives 7a and 7b would have low, long-termrisks, but the remedy would take longer to achieve cleanup objectives. TheProposed Plan does not compare remediation times for Alternatives 7a and 7b toother alternatives. Therefore, the phrase "would take longer" is meaningless. TheFFS explains that with hydraulic capture established, the portion of thecontaminant plume downgradient of the hydraulic barrier is expected to attenuateto MCLs by the year 2017. However, continued operation of the remedy beyond2017 would be required until on-Site groundwater quality reached MCLs.

Response - Alternatives 7a and 7b are also viable. However, EPA believesAlternative 6 coupled with MNA lias a higher probability of success of meetingthe site's cleanup objectives and is cost effective when compared to thealternatives presented in the FFS.

9. Pg. 6, left column, last para. - Alternative 6 is described as accelerating thenatural destruction of VOCs at the source area and in the shallow aquifer. Directtreatment of the vadose zone was. eliminated during the technology screening stepof the FFS (See General Comment No. 1 and Specific Comment Nos. 4 and 5).

Response - Source area refers to the contaminated aquifer under the Hatchcoproperty. As stated in previous responses and the PP Public Meeting, the intentof Alternative 6 is to treat the aquifer. EPA's expectation is to decreasecontaminant concentrations in the saturated soils and the groundwater plume.

The text goes on to state that Alternative 6 would decrease the time needed toachieve cleanup objectives onsite and offsite. The Proposed Plan does not

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compare remediation times for Alternatives 6 to other alternatives. Therefore, thephrase "would decrease the time needed" is meaningless. A remedy consisting ofa failed attempt to treat the vadose zone coupled with up to 13 biannual treatmentsof the aquifer will not significantly decrease the time needed to achieve cleanupobjectives when compared with any of the other alternatives.

Response - The third paragraph of the introduction of the Proposed Planencourages the public to review other documents included in the AdministrativeRecord. Remediation times are described in the FFS report. The information onthe number of treatments EPA considered for treating the aquifer is presented inthe Final FFS report. The statement that it will take up to 13 biannual treatmentsto treat the aquifer is inconsistent with the information presented in the Final FFSreport.

10. Pg. 6, right column, 2nd para. - Alternative 6 is described as enhancing the naturaldestruction of VOCs at the source area and in the shallow aquifer. See SpecificComment No. 9.

Response — Source, as presented in the referenced paragraph, is the portion of theaquifer located under the Hatchco property. Shallow aquifer is the entire TCEgroundwater plume. See response to Specific Comment No. 9.

11. Pg. 6, right column, 6th para. - EPA states that Alternative 6 would take the leasttime to achieve final cleanup levels on and offsite (less than 13 years).Alternative 6 would take the least time to achieve final clean-up levels only if theresidual contaminant mass in the vadose zone was destroyed through in-situtreatment. The likelihood of this is considered very low as discussed in the FFSand General Comment No. 1.

The 13-year remediation time frame predicted by EPA under Alternative 6 isunsubstantiated. Through modeling, the FFS concluded that with completehydraulic containment established at the property boundary, the down-gradientportion of the plume would attenuate to MCLs within 13 years. This scenariomay not be applicable to Alternative 6 for the following reasons:

> Complete destruction of residual contaminant mass in the vadose zone viain-situ treatment is a very low probability scenario.

> Complete destruction of the on-Site dissolved phase plume would have tooccur in the same time frame as the establishment of hydraulic capture.Hydraulic capture would most likely require a much shorter time frame.

Response - As noted above, the impact of residual mass in the vadose zone ongroundwater concentrations is unknown, but site redevelopment is likely todecrease that impact. If Hatchco would like to consider the use of soil vaporextraction to reduce the soil concentrations below the site, EPA would accept thatapproach. Significant shortcomings exist in the modeling for anything but

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screening purposes, so the 13 years is simply a relative number. If thebioremediation approach incorporates recirculation for hydraulic control, then itwould be equivalent to hydraulic containment, while also destroying thecontaminants in the source area.

12. Pg. 7, Table 2 - The present value of Alternative 6 assumes five, biannualtreatment events where only the saturated zone is treated. The cost of vadose zonetreatment and additional treatment of the saturated zone beyond the five, biannualevents is not included. Therefore, the actual cost of the preferred remedydescribed by EPA will be significantly higher (See General Comment No. 1)

Response - Alternative 6 is not for vadose zone soils

Treatment of the secondary source is not the responsibility of Hatchco as thesecondary source is located 1200 feet from the Site.

Hatchco has not fully demonstrated to EPA that it is not responsible for thecontamination at the alleged secondary source. Results for the remedialinvestigation for OU2 do not provide any evidence that a secondary source existsin the vicinity of the Jensen Automobile shop. Even if Hatchco can demonstrateto EPA that, indeed, there is a secondary source, we know the contaminationemanating from the Hatchco property may be commingled with a potentialsecondary source. This fact alone makes Hatchco join and several liable for thecontamination at the alleged secondary source.

13. Pg. 7, right column, 1st para. - EPA describes the Preferred Alternative asincreasing the breakdown rate of VOCs in sub-soils and in groundwater throughtreatment. See Specific Comment No 9.

Response - See response to Specific Comment No 9.

14. Pg. 7, right column, 2nd para. - EPA states that source remediation is needed atthis Site because the evidence of natural attenuation in the groundwater at the Siteis limited. See General Comment No. 2.

Response/Clarification - Source area (aquifer under the Hatchco property) at theSite. See response to General Comment No 2.

15. Pg. 7, right column, 3rd para. - EPA states that Alternative 6 will achievesubstantial risk reduction through treatment/destruction of contaminants in thesub-soil and in groundwater both on and offsite. The accelerated breakdown ofVOCs is expected to result in an increase in the production of vinyl chloridewhich is more mobile in soil vapor and more toxic than the parent chemicals. SeeGeneral Comment No. 3.

Response - See response to General Comment No 2 and No 3.

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16. Pg. 7, right column, 5th para. - EPA explains that it will conduct five-year reviewsuntil contaminant levels in soil and groundwater do not pose an unacceptable riskto human health and the environment. However, on Pg. 3 EPA states that currentsoil conditions are protective of human health.

Response - See response to General Comment No 2 & 3

17. Pg. 7, right column, 7th para. - EPA explains that the Preferred Alternative usesalternative treatment technologies to the maximum extent practicable. WhileHatchco recognizes EPAs preference for innovative technologies, Hatchco objectsto the advancement of a technology that is expected to fail. See Specific CommentNo. 9.

Response - It is difficult to ascertain Hatchco's position on use of an innovativetechnology when they have used the same technology without enhancement tosupport the remedy ofMNA. Hatchco has offered no evidence or support for itsassertions that EPA's alternative will fail. EPA maintains that appropriateapplication of the preferred alternative has a high probability of success, andmight even enjoy synergy with the redevelopment strategy for the site.

Hatchco has expended approximately $600,000.00 to date on independent remedialactions and in meeting the requirements of the Administrative Order on Consent (AOC).Thus, Hatchco is disinclined to enter into an AOC for remedial design and remedialaction under the preferred remedy described in the Proposed Plan for the followingreasons detailed in our general and specific comments:

• Available data do not support EPAs conclusion that it is necessary to treat vadosezone soils to restore the aquifer in a reasonable tune frame.

Response - Hatchco states vadose zone soils do not require treatment, andtherefore MNA alone could be used. Hatchco has not supported this assertion,and furthermore has stated Alternative 6 will fail because it does not treat vadosezone soils. Such a contradiction cannot be supported.

• The treatment method proposed by EPA for vadose zone soils is likely to fail asdetermined during the FFS and more recently through an independent analyses byRegenesis.

Response - Alternative 6 does not apply to vadose zone soils. Regenesis productshave no relevancy to the technology proposed by EPA.

• The treatment method proposed by EPA for groundwater is impracticable and willinterfere with future land use.

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Response - As noted above, future land use is not only compatible with thepreferred alternative, it may offer synergy.

• Implementation of institutional controls renders active remediation unnecessaryfor the short- and long-term protection of human health and the environment.

Response - Institutional controls will not protect the domestic wells from beingcontaminated.

Conclusion on the Applicability ofMNA at the Hatchco Site.

While the field data indicate reductive dechlonnation has occurred in the past or may beoccurring now, as evidenced by tlie metabolic products (cis-DCE and VC), the evidence that itwill continue to occur is completely lacking in the RI and the FFS. The biogeocliemical datapresented are not adequately explained or presented in a manner to support the selection ofMNAor intrinsic biodegradation oftlie contaminants as tlie prejerred alternative for this site. Theexplanation presented by Hatchco oftlie biological mechanisms occurring in tlte groundiuater areintended to support natural attenuation are inaccurate, misapplied or misunderstood and do notsupport the conclusion of intrinsic biodegradation of the contaminants leading to a selection ofMNA. The four quarters of groundwater monitoring did not show a decrease in concentrationsof contaminants nor were any data collected to support biological degradation oftiiecontaminants within the system. Tterefore, Hatchco relied solely on the modeling to determineMNA was an appropriate and effective remedial technology for this site. Hatchco claims to havefollowed, the. EPA protocol for evaluating natural attenuation in groundwater. Hoivever, theEPA protocol directs the proponent ofMNA to conduct a full characterization in support of thisremedial option if the screening data appear to support any or all of the attenuation mechanismsas a significant factor in contaminant removal. TJiis characterization was not conducted. In factthe preliminary screening data support tlie conclusion that MNA is not occurring to anysignificant degree. Hatchco has attempted to accept the negative site screening data as indirectsupport of reductive dechlonnation and move immediately to the use of fate and transportmodeling to support an MNA alternative with no basis or an unknown basis for contaminantconcentration reduction.

EPA has reviewed the site groundwater data and tlie data suggest the biological communityrequired for complete dechlonnation is likely present or has been present in the past to producethe metabolic products. However, tlie groundwater system appears to be limited in availableelectron donor (TOC) to drive the reductive dechlonnation processes required to achieve completereductive dechlonnation, i.e., production ofetliene. This is supported by the field data presentedin the FFS 2004 (low TOC). Tlierefore, a logical interpretation of the data is that availableelectron donor is lacking and in-situ biodegmdation could be enhanced by adding an organicelectron donor into the aquifer near tlie source zone. MNA is likely an appropriate technology forthe downgradient plume if tlie source area is reduced by an alternative technology.

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bountiful/woods cross/5th south pce plume npl site · 2.3 scope and role of operable unit or...

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