epa superfund record of decisionsep 30, 2002 · the duracell facility currently consists of three...

EPA/ROD/R04-02/5882002

EPA Superfund

Record of Decision:

BATTERY TECH (DURACELL-LEXINGTON)EPA ID: NCD000648402OU 02LEXINGTON, NC09/30/2002

BATTERY TECH DURACELL SITE

RECORD OF DECISIONOPERABLE UNIT TWO

U.S. ENVIRONMENTAL PROTECTION AGENCYREGION IV

ATLANTA, GEORGIA

SEPTEMBER 2002

TABLE OF CONTENTS Description Page

DECLARATION FOR THE RECORD OF DECISION Site Name and Location Statement of Basis and Purpose Assessment of the Site Description of the Selected Remedy Statutory Determination Data Certification Checklist

DECISION SUMMARY 1

1.0 SITE NAME AND LOCATION 1

2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 1

3.0 COMMUNITY PARTICIPATION 3

4.0 SCOPE AND ROLE OF OPERABLE UNIT TWO 5

5.0 SUMMARY OF SITE CHARACTERISTICS 55.1 Surface Features 55.2 Meteorology 65.3 Surface Water Hydrology 65.4 Geology 85.5 Hydrogeology 8

6.0 SITE CHARACTERISTICS 86.1 Summary of Shallow Ground Water Contamination 10

6.1.1 Inorganic Constituents in Shallow Ground Water 106.1.2 Organic Compounds in Shallow Ground Water 13

6.2 Summary of Bedrock Ground Water Contamination 176.2.1 Inorganic Constituents in Bedrock Ground Water 18 6.2.2 Organic Compounds in Bedrock Ground Water 19

6.3 Summary of Private Well Water Contamination 22

7.0 CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES 24

8.0 SUMMARY OF SITE RISKS 258.1 Identification of Chemicals of Concern 258.2 Summary of Exposure Assessment 268.3 Summary of Toxicity Assessment 268.4 Risk Characterization 31

8.4.1 Summary of Carcinogenic Risk 328.4.1.1 Exposure to Shallow Ground Water 328.4.1.2 Exposure to Bedrock Ground Water 33


8.4.2 Summary of Non-Carcinogenic Risk 338.4.1.1 Exposure to Shallow Ground Water 348.4.2.2 Exposure to Bedrock Ground Water 35

8.5 Uncertainties Associated With Risk Characterization 36

9.0 REMEDIATION OBJECTIVES 37

10.0 SUMMARY OF REMEDIAL ALTERNATIVES 3810.1 Description of Each Alternative 38

10.1.1 Alternative 1 3810.1.2 Alternative 2 3810.1.3 Alternative 3 38 10.1.4 Alternative 4 39 10.1.5 Alternative 5 39 10.1.6 Alternative 6 40

10.2 Criteria for Evaluating Remedial Alternatives 4010.3 Detailed Analysis of Each Alternative 45

10.3.1 Alternative 1 4510.3.2 Alternative 2 4610.3.3 Alternative 3 4810.3.4 Alternative 4 5210.3.5 Alternative 5 5710.3.6 Alternative 6 61

10.4 Comparative Analysis of Remedial Alternatives 6510.4.1 Short-Term Effectiveness 6510.4.2 Long-Term Effectiveness and Permanence 6510.4.3 Reduction of Contaminant Toxicity, Mobility, and Volume 65 10.4.4 Implementability 66 10.4.5 Compliance with Applicable or Relevant and Appropriate Requirements

(ARARs) 6610.4.6 Overall Protection of Human Health and the Environment 66 10.4.7 Cost 67 10.4.8 State Acceptance 6710.4.9 Community Acceptance 67

11.0 THE SELECTED REMEDY 6711.1 Description of the Alternative 3 6711.2 Summary of Estimated Costs for Alternative 3 6811.3 Expected Outcome of Alternative 3 68

12.0 STATUTORY DETERMINATIONS 73

APPENDIX A - RESPONSIVENESS SUMMARY


LIST OF FIGURES

FIGURE DESCRIPTION 1 Site Location Map 22 Duracell Facility Diagram 43 Site Conceptual Model 74 Location of Mercury Plume in Shallow Ground Water 135 Location of Trichloroethene Plume in Shallow Ground Water 17

LIST OF TABLES

TABLE DESCRIPTION

1 Summary of Inorganic Constituents in Shallow On-Site Ground Water 112 Summary of Inorganic Constituents in Shallow Off-Site Ground Water 123 Summary of Volatile Organic Compounds in Shallow On-Site Ground Water 144 Summary of Volatile Organic Compounds in Shallow Off-Site Ground Water 165 Summary of Inorganic Constituents in On-Site Bedrock Ground Water 186 Summary of Inorganic Constituents in Off-Site Bedrock Ground Water 197 Summary of Volatile Organic Compounds in On-Site Bedrock Ground Water 208 Summary of Volatile Organic Compounds in Off-Site Bedrock Ground Water 219 Summary of Inorganic Constituents in Off-Site Private Wells 2310 Summary of Volatile Organic Compounds in Off-Site Private Wells 2411 Summary of Site-Specific Chemicals of Concern 2712 Summary of Site-Specific Exposure Point Concentrations 2813 Summary of Site-Specific Exposure Pathways 29,3014 Risk Characterization Summary - Carcinogens in On-Site Ground Water 3415 Risk Characterization Summary - Carcinogens in Off-Site Ground Water 3416 Risk Characterization Summary - Non-Carcinogens in On-Site Ground Water 3617 Risk Characterization Summary - Non-Carcinogens in Off-Site Ground Water 3618 Summary of Site-Specific Applicable or Relevant and Appropriate Requirements 43,4419 Estimated Total Present Worth Cost for Alternative 3 7020 Cleanup Levels for Chemicals of Concern 71,72

DECLARATION FOR THE RECORD OF DECISION

Site Name and Location Battery Tech Duracell Site Operable Unit Two (OU2) EPA ID# - NCD 000 648 402 To Address Ground Water Contamination Lexington, Davidson County, North Carolina

Statement of Basis and Purpose This decision document presents the selected remedy for Operable Unit Two (OU2) to address contaminatedground water at the Duracell Battery Tech Site (the Site) in Lexington, Davidson County, North Carolina. Thisremedy was chosen in accordance with the Comprehensive Environmental Response, Compensation, andLiability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of1986 (SARA), and to the extent practicable, the National Oil and Hazardous Substances PollutionContingency Plan (NCP). Selection of the remedy in this decision document is supported by the informationcontained in the Administrative Record for OU2.

The State of North Carolina concurs with the selected remedy.

Assessment of the Site The response action selected in this Record of Decision (ROD) is necessary to protect the public health orwelfare or the environment from actual or threatened releases of hazardous substances into the environment.

Description of the Selected Remedy

The selected final remedy implements a pump-and-treat system for containment and restoration ofcontaminated shallow and bedrock ground water with the option to enhance the final remedy with innovativetechnologies evaluated during remedial design.

The major components of the selected remedy are:

i Institutional Controls will be used to prohibit future residential use of the Duracell facility, property, andto ensure that Site-related contaminated ground water, both on the facility property and off the facilityproperty, is not used for any household purposes in the future;

i Ground Water extraction and treatment will be used to contain the plume and prevent additional off-sitemigration of Site-related contaminants. The pump and treat system will consist of about 17 newextraction wells and treatment via clarification/solids removal, metals precipitation/filtration, and airstripping. Treated ground water will be discharged to the City of Lexington's wastewater treatmentsystem;

i Estimated capital, operation and maintenance (O&M), and total present worth costs; and the number ofyears over which the remedy cost estimates are projected; and

i Decisive factors that led to selecting the remedy (i.e., describe how the Selected Remedy provides thebest balance of tradeoffs with respect to the balancing and modifying criteria).

i Innovative technology evaluations (such as in-situ bioremediation, in-situ chemical oxidation,electrochemical techniques, and monitored natural attenuation) will be evaluated during the OU2Remedial Design. The objective of conducting these technology evaluations is to determine if one ormore of these technologies, used in conjunction with the selected remedy, could result in shortening theoverall remediation timeframe and/or provide a more cost-effective remediation.

Statutory Determinations

The selected remedy is protective of human health and the environment, complies with Federal and Staterequirements that are applicable or relevant and appropriate to this remedial action, is cost-effective, and utilizespermanent solutions and alternative treatment (or source recovery) technologies to the maximum extentpracticable. This remedy also satisfies, to the extent practicable, the statutory preference for treatment as aprincipal element of the remedy (i.e., reduce the toxicity, mobility, or volume of materials comprising principalthreats through treatment). Because this remedy will result in hazardous substances remaining on-site above health-based levels for an indefinite period of time, a review will be conducted within five years after initiation ofthe OU1 Remedial Action at the Site, and every five years thereafter, until the remediation goals are achieved,or it is determined by all parties that no further action is needed in order to provide adequate protection tohuman health and the environment.

Data Certification Checklist

The information listed below is included in the Decision Summary section of this ROD. Additional informationcan be found in the Administrative Record for this Site, including:

i Chemicals of Concern (COCs) and their respective ranges of concentrations; i Baseline risks represented by the COCs; i Cleanup levels established for COCs and the basis for the levels; i Current and future land use and ground water use assumptions used in the baseline risk assessment and

ROD; i Land and ground water use that will be available at the site as a result of the Selected Remedy;

ROD Battery Tech Duracell OU2

Page 1

DECISION SUMMARY

The Duracell Battery Tech facility encompasses approximately 27.5 acres in a light industrial/commercial areaof Lexington. The subject of this Record of Decision (ROD) is Operable Unit Two (OU2); which is EPA'sdesignation to address contaminated ground water associated with past operations at the Site.

1.0 SITE NAME AND LOCATION

Duracell Battery Tech Site EPA ID Number - NCD 000 648 402 Operable Unit Two (OU2) Lexington, Davidson County, North Carolina

2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

The Duracell site is located at 305 New Highway 64 East in Lexington, Davidson County, North Carolina.Figure 1 shows the general location of the Site. The 27.5-acre facility began operating in the 1950's. Previousowners/operators of the Site, including P.R. Mallory and Duracell, manufactured mercuric oxide batteries, aswell as dry cells for commercial and industrial use. Over the years, several plant operations have been added tothe Site to expand production. Over the years various types of batteries have been produced at the Site; thefollowing substances were used in the battery production:

i mercuric oxide powder i cadmium oxide powder i silver oxide powder i manganese dioxide oxide powder i manganese dioxide i graphite i zinc i elemental mercury i potassium hydroxide i lithium metal i ethylene glycol dimethylether

The Duracell facility currently consists of three main buildings; Plant #1, Plant #3, and Building #4. Plant #1 isthe battery cell assembly operation where chemicals are mixed and placed into containers to make batteries.

Plant #2 was the former building where mercuric oxide was formulated from 1977 to 1986; mercuryreclamation operations also took place on the east side of Plant #2 from 1977 to 1986. A small wastewatertreatment system consisting of two concrete-lined sumps was also in operation at Plant#2 prior to installation ofthe Memtek treatment system at Building #4. Plant #2 was demolished and removed from the Site in 1995.Plant #3 was purchased in 1976 and is utilized for testing, packaging, and shipping and receiving. Building #4was built in 1981 to house the mercury reclamation furnace; this building is now used to store hazardous wasteand house the wastewater treatment system. Figure 2 provides a detailed diagram of the Site.


Page 2

FIGURE 1 - SITE LOCATION MAP (Shows portion of site where OU2 Remediation Action will take place)


Page 3

Site Operations over the years resulted in extensive mercury contamination in the soil and groundwater at theSite. The main source of mercury contamination in the soil involved the past operations in the area of Plant#2.The mercury contamination in soil is being addressed as part of the Operable Unit One Remedial Action.Leaching of the mercury from the soil to the groundwater resulted in groundwater contamination. Mercury ispresent in the on-site groundwater at levels significantly higher than both State and Federal drinking waterstandards.

Runoff from the Site over the years has also resulted in elevated levels of mercury in the sediment of the surfacewater pathways draining the Site, including the unnamed tributary of Fritz Branch, Leonards Creek, andAbbotts Creek southward to High Rock Lake. A 1981 fish tissue study conducted in Abbotts Creek and HighRock Lake revealed levels of mercury in excess of one part-per-million. Since these levels of mercury in fishare considered unsafe for human consumption, a fish advisory was placed on portions of Abbotts Creek andHigh Rock lake in June 1981. In 1992, the measured levels of mercury in the fish decreased below theone-per-million level, and the fish advisory was lifted. Since that time, mercury concentrations in fish havecontinued to decline and NCDENR has determined that Abbotts Creek is now fully supporting its designateduses. The mercury contamination in sediment in the upper 2,000 feet of the unnamed tributary located north ofthe operating facility is being addressed as part of the Operable Unit One Remedial Action.

Volatile organic compounds such as acetone, methylene chloride, trichloroethene, tetrachloroethene,1,1,1-trichloroethane, and 1,1,2-trichloroethane were used in the past at the Site as cleaning solvents to cleantools, dyes, presses, watch battery cells, etc. The solvents were disposed of in an unlined pit located betweenBuilding #4 and Plant #1 from the early 1960s until the early 1970s. As a result, the soil in the area of theformer disposal pit contains volatile organic compounds. On-site groundwater became contaminated as thevolatile organic compounds migrated from the soil in the disposal pit downward into groundwater. Elevatedlevels of VOCs have also been identified in soil and ground water in the Plant #1 area. Volatile organiccompound contamination exists in the on-site groundwater at levels in excess of State and Federal drinkingwater standards.

The Site is not currently on the National Priorities List (NPL). However, an Administrative Order of Consentwas signed between EPA and Duracell in 1995 to perform the RI/FS. Duracell agreed to conduct the RI/FS,and will incur all appropriate costs associated with the RI/FS as outlined in the Administrative Order. Althoughthe Duracell Battery Tech Site is currently not on the NPL, EPA has prepared the listing package and plans topropose the Site for inclusion on the NPL in the future.

3.0 COMMUNITY PARTICIPATION

Pursuant to CERCLA § 113(k)(2)(B)(i-v) and § 117, the RI/FS Report and the Proposed Plan for OU2 weremade available to the public in July 2002. These documents can be found in the Administrative Record file andthe information repository maintained at the EPA Docket Room in Region 4 and at the Davidson County PublicLibrary, 602 South Main Street, Lexington, North Carolina. In addition, the OU2 Proposed Plan fact sheetwas mailed to individuals on the Site's mailing list on July 5, 2002.


Page 4

FIGURE 2 - DURACELL FACILITY DIAGRAM (Plant #2 no longer exists, but former location is shown)


Page 5

The notice of the availability of these documents and notification of the Proposed Plan Public Meeting wasannounced in The Dispatch in July 2002. A 30-day public comment period was held from July 11, 2002through August 10,2002. In addition, a public meeting was held on July 11, 2002, at the Agricultural Center inLexington. At this meeting, representatives from EPA made a presentation about the Site and the remedialalternatives under consideration for the OU2 Remedial Action. EPA's responses to comments received duringthe 30-day comment period, including those raised during the public meeting, are included in theResponsiveness Summary, which is part of this ROD. The Responsiveness Summary also incorporates atranscript of the Proposed Plan public meeting.

4.0 SCOPE AND ROLE OF OPERABLE UNIT TWO

Due to its complexity, the Site has been organized into two Operable Units. The objective of Operable UnitOne is to address Site-related soil and sediment contamination, and to implement a monitoring program forecological receptors. The OU1 Remedial Design will be completed in September 2002, and the OU1 RemedialAction will be initiated at that time. Operable Unit Two will address Site-related groundwater contamination. Aseparate Operable Unit Two RI Report, Baseline Risk Assessment, and Feasibility Study have been developedto characterize the ground water contamination, evaluate the risk associated with the contamination, andevaluate alternatives for addressing the groundwater contamination. After consideration was given to eachcomment received during the 30-day comment period, the Operable Unit Two Remedy was selected inSeptember 2002 to address the site-related ground water contamination.

5.0 SITE CHARACTERISTICS

This section presents a brief overview of the Site, including regional and site-specific surface features,meteorology, surface water hydrology, geology, soils, hydrogeology, climate, land use, and ecology. Thisinformation was drawn from observations and data collected during the Phase I, Phase II, and Phase III fieldinvestigations of the OU2 RI, as well as from previous studies, State and Federal databases, and publishedsources. Figure 3 shows the Site conceptual model developed during the RI/FS. The model provides agraphical depiction of the overall Site conditions, and illustrates the potential sources of contamination at theSite, primary release mechanisms, primary migration pathways, primary exposure pathways, as well as thepotential human and ecological receptors. The model shows how ground water was evaluated during the OU2Risk Assessment for the different exposure pathways and potential human receptors.

5.1 SURFACE FEATURES

The Site is located in central Davidson County, North Carolina. Davidson County is situated in the west-centralpart of North Carolina. Lexington is the Davidson County seat. The county is bounded on the north by ForsythCounty, on the east by Guilford and Randolph Counties, on the south by Montgomery County, and on the westby Rowan and Davie Counties, being separated from the last-named two counties by the Yadkin River. Thecounty encompasses an approximate 567-square mile area,

Davidson County is a plateau, dissected by numerous streams, which have cut deep, narrow valleys. Thesurface of the county is rolling to steeply rolling, and the lowlands along the streams constitute the only levelareas. Some of the interstream areas are gently rolling or undulating. In the southern half of the county, the


Page 6

topography becomes semi-mountainous in the vicinity of Cid, Denton, Jackson Hill, Bain, Newsom, and HighRock. Among the more prominent of the semi-mountainous areas are Flat Swamp, Three Hat, Rich, Wild Cat,Grist, and Bald Mountains. The higher elevations occur in the northern end of the county and the lowerelevations in the southwestern part, along the Yadkin River below High Rock Lake.

Site topography is rolling in the eastern portion, and the northern portion exhibits a slope towards the north toFritz Branch. The southern portion of the Site has a general southerly slope. The elevations vary from 760 ftmean sea level (MSL) at the Site to 640 ft MSL at Fritz Branch.

5.2 METEOROLOGY

Davidson County is generally hot and humid in the summer and moderately cold in the winter. The averagetemperature in the winter is 42/F (Fahrenheit) with the average daily minimum temperature 32/F. In thesummer, the average temperature is 78/F and the daily maximum temperature is 89 F. The total average annualprecipitation is approximately 45 inches. Usually 50 percent of the precipitation (23 inches) falls from Aprilthrough September. Thunderstorms occur on about 46 days each year. Every few years in late summer orautumn, a tropical storm moving inland from the Atlantic Ocean causes extremely heavy rain for one to threedays.

Average seasonal snowfall is eight inches. The average relative humidity in mid-afternoon is about 55 percent.Humidity is higher at night and the average at dawn is about 85 percent. The sun shines 65 percent of the timein summer and 55 percent in winter. The prevailing wind is from the southwest with the average wind speedbeing highest (nine miles per hour) in the spring.

5.3 SURFACE WATER HYDROLOGY

Davidson County falls within the Yadkin-Pee Dee River Basin. Numerous small tributaries drain central NorthCarolina and discharge to the Yadkin River. The Abbotts Creek watershed encompasses approximatelyone-third of Davidson County and empties into the Yadkin River at High Rock Lake. The Yadkin River at HighRock Lake, under the North Carolina Administrative Code (NCAC) Section 15A. 2B. 0309, is classified asClass WS-IV waters. Class WS-IV waters are protected as water supplies, which are generally in moderatelyto highly, developed watersheds. In addition, these waters must be suitable for all Class C uses. Class Cfreshwaters are protected for secondary recreation, fishing and aquatic life propagation and survival.

Storm water runoff from the northern portion of the Site drains generally to the north/northeast into threeunnamed tributaries. One tributary drains northeasterly into Fritz Branch, a small perennial flow stream whichflows from west to east and terminates in Leonards Creek, approximately 2,000 ft upstream of Abbotts Creek.

The second tributary also drains easterly to Leonards Creek about 500 ft upstream of Abbotts Creek, and is anintermittent stream which can go dry during extended periods of low rainfall. The third northern tributary drainseastward from Plant #3 to Leonards Creek near the confluence with Abbotts Creek. Runoff from the southernportion of the Site drains to the south/southeast to an unnamed tributary of Abbotts Creek. Abbotts Creekdrains into High Rock Lake approximately 8.5 miles downstream from the Site. Both Leonards Creek andAbbotts Creek are classified as Class C waters.


Page 7

FIGURE 3 - SITE CONCEPTUAL MODEL


Page 8

5.4 GEOLOGY

Davidson County is located in the center of the Piedmont physiographic province. Davidson County is on theboundary between two major geologic belts, the Charlotte Belt to the north and the Carolina Slate Belt to thesouth (Carpenter, 1982). The Charlotte belt is characterized by both felsic and mafic igneous rocks. The felsicrocks are primarily granite, gneiss, and schist, while the mafic rocks are primarily gabbro. The Carolina SlateBelt includes various types of volcanic and sedimentary rocks, such as mudstones, and mixtures of volcanicdebris. Soils that are formed in material weathered from this type of rock are acidic. Soils that formed inmaterial weathered from this type of rock are slightly acidic to mildly alkaline. Large areas of the county areunderlain by intermediate rocks, such as diorite, or have a mixture of felsic and mafic rocks. The fine-grained metamorphic rocks are slate-like rocks that are dominantly argillite. Soils formed in material weathered fromthese rocks are acidic. Soil textures vary depending on the mineralogy or the parent material (e.g. the schistsproduce micaceous silts while gneiss or intrusives produce silty or sandy clays). The soil beneath the Sitegenerally consists of varying thicknesses of weathered bedrock or saprolite, which is composed ofpredominantly silty clays to clayey silts. Fractured bedrock is located beneath the soil. The fractured bedrockconsists primarily of white to gray, fine to coarse-grained, massive to foliated, granites, grano-diorites, quartzdiorites, and quartz monzonites on the west side of the facility. The intermediate intrusive rocks on the east sideof the facility consist of dark, greenish-gray to black, medium-to-coarse grained, massive, well-jointedmetamorphosed bodies, probably dioritic in composition.

5.5 HYDROGEOLOGY

Ground water in the general vicinity of the Site exists within two zones. The first or uppermost, water-bearingzone is within the silty clay residual saprolite soils overlying the bedrock. The second, or lower, water-bearingzone is within the underlying igneous bedrock where the occurrence and movement of ground water iscontrolled by secondary openings such as fractures, joints, and foliations. The majority of ground water in theuppermost water-bearing zone exists along relic structures such as fractures. Ground water in the saprolite isusually found under unconfined or semi-confined conditions with ground water flow generally conforming tosurface topography. Due to the low permeability of the fine-grained materials comprising the uppermostwater-bearing zone, ground water yields to wells tapping this zone are very small and typically not sufficient forwater supply purposes.

Ground water in the lower water-bearing zone in bedrock is typically under semi-confined or confinedconditions with flow direction being controlled by the presence and orientation of secondary openings. Groundwater movement generally occurs from areas of higher hydraulic head (higher elevations) toward areas of lowerhydraulic head (lower elevations or stream valleys). Ground water yields from the bedrock are typically higherthan the upper zone above bedrock with yields high enough to sustain private water supplies. Private waterwells tapping the bedrock aquifer and the shallower saprolite zone are present in the general vicinity of the Site.

6.0 SITE CHARACTERISTICS

This section provides a brief summary of major investigative activities conducted as part of the OU2 RI. In thefollowing discussion of the ground water investigation activities for the saprolite and bedrock zones, referencehas been made to on-site and off-site monitoring wells. The Battery Tech Duracell Site consists of


Page 9

approximately 145 acres that includes a 27.5-acre battery manufacturing facility. An additional 17.5undeveloped acres were acquired by Duracell in 1992, and approximately 100 undeveloped acres wereacquired by Duracell in 1999. By definition, the "Site" includes all areas where site-related contamination isknown to have spread. In an attempt to distinguish between the site-related contamination located within thefacility fence line from the contamination outside the facility fence line, the term "on-site" refers to the 27.5-acrearea within the facility fence line, while the term "off-site" refers to the areas outside the facility fence line.

A total of 57 shallow (saprolite) monitoring wells, one shallow (saprolite) recovery well, 36 deep (bedrock)monitoring wells, and four deep (bedrock) recovery wells have been installed to characterize both on- andoff-site ground water quality and flow in the shallow, uppermost water bearing zone and the deeper, bedrockwater bearing zone on and around the Site. Each of these wells was sampled on at least two separate occasionsduring the OU2 RI, and analyzed for a wide range of analytical parameters, including:

i the six site-specific inorganic compounds cadmium, chromium, manganese, mercury, silver, and zinc;

i Target Analyte List (TAL) inorganic compounds plus lithium; and

i Target Compound List (TCL) organic compounds, which included volatile organic compounds(VOCs), semi-volatile organic compounds (SVOCs), and pesticides/PCBs.

A total of 16 temporary wells were installed in two off-site areas with four of these temporary wells beingdrilled off-site to the north and 12 of the temporary wells being drilled off-site to the south. These temporarywells were installed to collect shallow ground water samples for preliminary definition of the horizontal extent ofthe VOC plume, and as a screening tool to finalize the locations of permanent shallow ground water monitoringwells. Ground water was not encountered in many of the temporary wells and, therefore, only six temporarywells ultimately were sampled. Ground water samples that were collected from the six temporary wells were analyzed for VOCs.

Short term slug tests and longer term pumping tests were performed at certain shallow saprolite well locationsand deep bedrock well locations on the Site to evaluate the hydraulic conductivity and other hydraulicparameters of the aquifer, as well as to determine the hydraulic interconnection between nearby monitoringwells. The results of the slug tests conducted for wells in the shallow saprolite water-bearing zone indicatedhydraulic conductivity values ranging from 0.37 ft/day to 4.6 ft/day. The hydraulic conductivities calculated fromthe pump tests ranged from 0.008 to 0.37 ft/day. These values were within the range listed in Freeze andCherry (1979) for fractured igneous and metamorphic rock of 0.003 to 30 ft/day.

Hydraulic modeling of the ground water system beneath the Duracell-Lexington Site was conducted with theTWODAN model. The model-derived transmissivity for the northern portion of the Duracell-Lexington Sitewas 25 to 100 ft2/day, while the transmissivity calculated from pump test data for DR-1 was 60 ft2/day. In thesouthern Site area, the transmissivity values derived from the model ranged from 10 to 40 ft2/day.

A conceptual ground water flow model was developed as a 2-dimensional flow system with uniform regionalinfiltration and uniform and anisotropic regional aquifer transmissivity. The aquifer water levels are controlledand constrained by surrounding surface water bodies, such as rivers and streams. Hydraulic modeling of the


Page 10

ground water system beneath the Site was also conducted using the TWODAN model. The aquifertransmissivity varies with various orientations; the model-derived transmissivity for the northern portion of theSite was 25 to 100 ft2/day, and 10 to 40 ft2/day in the southern portion of the Site.

In order to establish site-specific background concentrations of various inorganic and organic constituents,ground water samples from shallow monitoring wells installed in the saprolite waterbearing zone and deepmonitoring wells installed in the bedrock water-bearing zone were collected at locations hydraulicallyup-gradient from the Site so as to not be impacted by potential releases from the facility, yet near enough to theSite to be more representative of local conditions.

The following subsections provide a summary of the analytical results for the shallow and deep (bedrock)ground water samples collected as part of this RI.

6.1 Summary of Shallow Ground Water Contamination

Extensive sampling was conducted of 30 on-site shallow monitoring wells, one shallow recovery well, and 9temporary monitoring wells (Geoprobe borings) completed in the unconsolidated saprolite zone abovebedrock. This sampling was conducted in order to determine the presence and extent of site-specific inorganicand organic constituents of concern in the shallow ground water beneath the Site. Ground water samples alsowere collected from 21 off-site saprolite monitoring wells to determine the presence and extent of site-specificinorganic and organic constituents of concern that might have migrated from the Site to off-site areas.

All of the shallow monitoring wells were sampled on at least two separate occasions with analyses of cadmium,chromium, manganese, mercury, silver, zinc, and TCL VOCs being conducted on all samples. In addition,supplemental analyses of other compounds, including TAL inorganics, TCL SVOCs, and TCLpesticides/PCBs, were performed to assess the potential that other constituents might be present atconcentrations of concern. Conductivity, pH, temperature, and turbidity were analyzed in all shallow monitoringwells as field parameters during each ground water sampling survey to establish water quality and to verify thatthe ground water had reached steady-state conditions prior to sampling.

6.1.1 Inorganic Constituents in Shallow Ground Water

A total of 113 shallow on-site ground water samples, including background samples, were analyzed for one ormore of the six site-specific inorganics (i.e., cadmium, chromium, manganese, mercury, silver, and zinc). The sixinorganic constituents were identified early in the RI process as potential constituents of concern based on thehistory of operations at the Site and existing data. Of these 113 samples, 23 shallow on-site ground watersamples were analyzed for mercury and manganese only. The frequencies of detection, concentration ranges,and locations of the maximum detected concentrations for the six site-specific inorganics in the shallow on-siteground water are presented below in Table 1. Wide ranges of concentrations were detected for four of the sixsite-specific inorganics (i.e., chromium, manganese, mercury, and zinc). Cadmium and silver were consistentlynot detected or detected at very low concentrations.


Page 11

TABLE 1 - SUMMARY OF INORGANICS IN SHALLOW ON-SITE GROUND WATER

Inorganic Compounds

Frequency of Detection

Concentration Range (ug/L)

Average Concentration

(ug/L) 1Location of Max. Conc.

Cadmium 8 of 87 BDL to3.5 2.04 MW-8

Chromium 74 of 90 BDL to 256 22.4 MW-2

Manganese 111 of 113 BDL to 28,900 107 PLT-GW-4

Mercury 54 of 113 BDL to 2,030 89.8 MW-8

Silver 1 of 87 BDL to 2.7 0.18 MW-8

Zinc 33 of 88 BDL to 350 119 MW-2 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

Filtered/unfiltered samples collected from the shallow ground water and evaluated during the RI/FS indicate apositive correlation between the concentrations of several Site-related inorganic constituents in shallow groundwater, and the quantity of suspended solid and colloidal material present in the samples (i.e., turbidity).

Figure 4 shows the mercury plume in the shallow ground water on the Site localized to an area immediatelynorth of Plant #1. The primary source areas of the mercury in the shallow on-site ground water include theformer Plant #2 area, the Building #4 area, and the former solvent disposal area. The highest concentration ofmercury (2,030 ug/1) was detected in the shallow ground water in MW-8 downgradient of the former Plant #2area. Based on the sampling data collected as part of this RI, mercury has migrated in the shallow saproliteground water approximately 600 feet to the north of the known source areas.

Manganese was generally found at higher concentrations in the areas west and north of Plant #1. The highestmanganese concentration (28,900 ug/L) was measured beneath Plant #1 in PLT1-GW-4. The distributionpatterns for the remainder of the TAL inorganic constituents in shallow ground water across the Site, and inoff-site areas, were generally low and did not indicate a discernible correlation to the Site operations. Based onthe history of operations at the Site, the remainder of the inorganic constituents have not been documented asconstituents of concern in shallow ground water at the Site.

In addition, a total of 56 off-site shallow ground water samples, including background samples, were collectedand analyzed for one or more of the six site-specific inorganics. The concentration ranges and locations of themaximum detected concentrations for the six site-specific inorganics in the off-site shallow ground water arepresented below in Table 2.


Page 12

TABLE 2 - SUMMARY OF INORGANICS IN OFF-SITE SHALLOW GROUND WATER

Inorganic Constituents


Concentration Range

Average 1

Concentration (ug/L)

Location of Maximum

Concentration

Cadmium 4 of 49 BDL to 4.1 0.25 MW-36

Chromium 47 of 52 BDL to 21,800 481 MW-49

Manganese 56 of 56 6.6 to14,100 980 MW-35

Mercury 15 of 56 BDL to l3.1 0.55 MW-27

Silver 2 of 49 BDL to 1.7 0.16 MW-44

Zinc 18 of 49 BDL to 606 51.8 MW-53 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

A total of 110 shallow on-site saprolite ground water samples, including background samples, and nine samplesfrom temporary monitoring wells, were analyzed for TCL VOCs. The frequencies of detection, concentrationranges, and the locations of the maximum concentrations of the dominant VOCs detected in the shallow on-siteground water are presented in Table 3.


Page 13

FIGURE 4 - LOCATION OF MERCURY PLUME

6.1.2 Organic Compounds in Shallow Ground Water

A total of 110 shallow on-site saprolite ground water samples, including background samples, and nine samplesfrom temporary monitoring wells, were analyzed for TCL VOCs. The frequencies of detection, concentrationranges, and the locations of the maximum concentrations of the dominant VOCs detected in the shallow on-siteground water are presented in Table 3.


Page 14

TABLE 3 - SUMMARY OF VOCs IN SHALLOW ON-SITE GROUND WATER VOC

VOCFrequency of

Detection Concentration

Range

Average 1

Concentration (ug/L)

Location of Maximum

Concentration

Tetrachloroethene 24 of 110 BDL to 62 2.47 SR-6

Trichloroethene 60 of 110 BDL to 170,000 593 PLT1-GW5

1,1,1-Trichloroethane 56 of 110 BDL to 1,700 81.7 MW-15

1,1,2-Trichloroethane 1 of 110 BDL to 1(J) 0.57 PLT1-GW4

1,2-Dichloroethene (total)

38 of 110 BDL to 6,100 186 PLT1-GW4

1,1-Dichloroethene 63 of 110 BDL to 2,100 112 PLT1-GW4

1,2-Dichloroethane 2 of 110 BDL to2 (J) 0.54 MW-11

1,1-Dichloroethane 34 of 110 BDL to 320 11.5 MW-15

Methylene Chloride 18 of 110 BDL to 3,400(J) 32.5 MW-24

Acetone 16 of 110 BDL to 280 8.63 MW-24

Toluene 3 of 110 BDL to 38(J) 0.79 MW-24 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

In addition, a total of 70 off-site shallow ground water samples, including background samples and sevensamples from temporary wells, were analyzed for TCL VOCs. The frequencies of detection, concentrationranges, and the locations of the maximum concentrations of the dominant VOCs detected in the shallow off-siteground water are presented in Table 4.

Analytical data collected during the RI indicates several likely source areas for the TCE. One likely source areais the former solvent disposal area. The former solvent disposal area was used for the disposal of spent solventsprior to 1980; data from this area historically has shown elevated levels of VOCs including TCE. Elevatedlevels of TCE were also detected beneath Plant #1 at concentrations up to 170,000 ug/L. This data suggeststhat an additional source of VOCs could be present beneath or immediately adjacent to Plant #1.


Page 15

TABLE 4 - SUMMARY OF VOCs IN SHALLOW OFF-SITE GROUND WATER VOC

VOCFrequency of


Range Average 1

(ug/L)

Location of Maximum

Concentration

Tetrachloroethene 2 of 70 BDL to 4 (J) 0.44 MW-28

Trichloroethene 30 of 70 BDL to 18,000 134 MW-45

1,1,1-Trichloroethane 22 of 70 BDL to 260 13.4 MW-37

1,1,2-Trichloroethane 1 of 70 BDL to 1(J) 0.57 MW-47

1,2-Dichloroethene 26 of 70 BDL to 920 63.0 MW-45

1,1-Dichloroethene 24 of 70 BDL to 300 19.8 MW-28

1,2-Dichloroethane 0 of 70 BDL 0.52 Not Applicable

1,1-Dichloroethane 13 of 70 BDL to 48 (J) 2.35 MW-28

Methylene Chloride 4 of 70 BDL to 7 (J) 0.85 MW-37

Acetone 9 of 70 BDL to 6,200 92.5 MW-29

Toluene 0 of 70 BDL 0.40 Not Applicable 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

The dominant VOC in the shallow ground water, based on frequencies of detection and concentrations, istrichloroethene (TCE). Figure 5 shows the north- and south ward-trending TCE plume in shallow groundwater. The TCE plume extends to the north approximately 1,100 feet from the former solvent pit area, andapproximately 2,500 feet to the south from the former solvent pit area. The bi-directional TCE plume (and theplumes for other VOCs) in the shallow ground water is believed to be associated with the location of one ormore sources of TCE (and other VOCs) being located on or close to an east-west tracking ground waterdivide.

The distribution of 1,1,1-TCA and 1, 2-DCE in on-site shallow ground water is similar to that of TCE;however, the concentrations are lower and the extent of the plume is much more localized. The higherconcentrations of 1,1,1-TCA are associated with the northern component of the plume with the highestconcentration (1,700 ug/L) measured in MW-15. The two highest recent concentrations of 1,2-DCE weremeasured in PLT1-GW4 (6,100 ug/L) and MW-15 (1,500 ug/L). The presence of 1,2-DCE indicates thatTCE is undergoing reductive dechlorination. The presence of 1,1-DCA and 1,1-DCE indicates that 1,1,1-TCAis undergoing reductive dechlorination. Vinyl chloride was identified in 1996 in two on-site shallow monitoringwells at very low concentrations. There are no indications that there is an appreciable presence of vinyl chloridethat is associated with the distribution of other chlorinated VOCs, or the reductive dechlorination of theseVOCs. Chloroethane was identified in 1996 in one shallow ground water monitoring well at a concentration of


Page 16

2 ug/L. Neither vinyl chloride nor Chloroethane were detected in any of the shallow off-site ground watersamples.

The chlorinated ethanes (1,1,2,2-tetrachloroethane; 1,1,2-trichloroethane; and 1,2-dichloroethane) weredetected in two or less samples each, and were not detected above 5 ug/L in any shallow ground watermonitoring well. Tetrachloroethene was detected several times in the shallow ground water system in monitoringwells near the former solvent disposal area. This may indicate that low quantities of tetrachloroethene have beenreleased from this source. Tetrachloroethene was detected twice in the shallow off-site ground water system at4 ug/L or less.

Methylene chloride has been detected in several shallow ground water monitoring wells at concentrationsgenerally below 31 ug/L. Methylene chloride concentrations have not exceeded 7 ug/L in any shallow groundwater monitoring well since July 1996. Chloroform also was detected in several shallow ground watermonitoring wells at relatively low concentrations.

Non-halogenated VOCs, including ketones such as acetone and methyl ethyl ketone, and aromatic compoundssuch as toluene and xylenes, were also detected in the shallow ground water. The concentrations of theseVOCs were substantially lower than the concentrations of the previously discussed halogenated VOCs. Therewas no identifiable plume associated with any ketone or aromatic VOC.

Thirty-five (35) ground water samples, including background samples collected from the on-site shallowmonitoring wells, were analyzed for TCL SVOCs. In addition, 31 ground water samples, including backgroundsamples, collected from the off-site shallow monitoring wells, were analyzed for TCL SVOCs.

Seven SVOCs were detected in one or more on-site shallow ground water monitoring wells. Of these, bis(2-ethyl hexyl) phthalate (DEHP) was detected in six on-site shallow ground water samples at a maximumconcentration of 11 ug/L (MW-7). DEHP also was detected in four off-site shallow ground water samples,with a maximum concentration of 3 ug/L (MW-44). Six different PAHs were detected in one or more shallowground water monitoring wells at relatively low concentrations. Nineteen ground water samples from the on-siteshallow monitoring wells were analyzed for TCL pesticides and PCBs. Five different chlorinated pesticideswere detected in the shallow ground water at relatively low concentrations. No PCBs were detected in any ofthe shallow ground water samples.

Three ground water samples from a single off-site shallow monitoring well (MW-27) were analyzed for TCLpesticides and PCBs. Two different chlorinated pesticides were detected in the shallow off-site ground water atvery low concentrations. No PCBs were detected in any off-site shallow ground water samples.


Page 17

FIGURE 5 - LOCATION OF TRICHLOROETHENE PLUME

6.2 Summary of Bedrock Ground Water Contamination

Extensive sampling was conducted of on-site and off-site deep monitoring wells completed in the underlyingbedrock to determine the presence and extent of site-specific inorganic and organic constituents of concern inthe deep, bedrock ground water beneath and in the immediate vicinity of the Site. All of the deep monitoringwells were sampled on at least two separate occasions and analyzed for cadmium, chromium, manganese,mercury, silver, zinc, and TCL VOCs. In addition, supplemental analyses of other compounds, including theremainder of the TAL inorganics, TCL SVOCs, and TCL pesticides/PCBs, were performed.


Page 18

A total of 63 on-site bedrock ground water samples were sampled and analyzed. The frequencies of detection,concentration ranges, and locations of the maximum detected concentrations for the six site-specific inorganicsin the on-site bedrock ground water are presented in Table 5.

6.2.1 Inorganic Constituents in Bedrock Ground Water

Chromium was detected sporadically at typically low concentrations (less than 3 ug/L) in the bedrock groundwater at the Site. The highest chromium concentration reported for the most recent sampling event was 158ug/L.

Mercury has been detected in on-site bedrock ground water monitoring wells at concentrations up to 6.9 ug/L,and in bedrock ground water recovery wells at slightly higher concentrations. This indicates that under existingconditions at the Site, mercury is being released at a low rate to deeper ground water; the presence of mercuryin the deep ground water may be attributable to the influence of pumping conditions associated with therecovery wells. There is no evidence of a mercury plume in the off-site bedrock ground water. Mercury,cadmium, and silver were either detected at low frequencies and/or detected at low concentrations in theon-site bedrock ground water.

Zinc was detected in several of the on-site bedrock monitoring wells at concentrations up to 29,500 ug/L(DW-12), which is immediately downgradient of the former solvent disposal area. DW-12, along with DR-1,had the highest manganese concentration (10,600 ug/L) of the bedrock ground water monitoring wells.Increased solubility of metals such as zinc and manganese may be occurring in the former solvent disposal areawhere reductions in redox potential and pH is occurring.

A total of 52 off-site bedrock ground water samples, including background samples, were analyzed for the sixsite-specific inorganics. The frequencies of detection, concentration ranges, and locations of the maximumdetected concentrations for the six site-specific inorganics in the off site bedrock ground water are presented inTable 6.

TABLE 5 - SUMMARY OF INORGANICS IN ON-SITE BEDROCK GROUND WATER

Inorganic Compounds



Average 1

(ug/L) Location of Maximum

Concentration

Cadmium 6 of 60 BDL to 1.1 0.178 DW-12

Chromium 33 of 61 BDL to 158 6.64 DW-21

Manganese 61 of 63 BDL to 10,600 1,080 DR-1

Mercury 9 of 63 BDL to 6.9 0.23 DR-3

Silver 1 of 60 BDL to 0.6 0.13 DW-4

Zinc 44 of 61 BDL to 29,500 696 DW-12 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.


Page 19

TABLE 6 - SUMMARY OF INORGANICS IN OFF-SITE BEDROCK GROUND WATER

Inorganic Compounds



Average 1


Concentration

Cadmium 7 of 52 BDL to 0.77 0.16 DW-27

Chromium 24 of 52 BDL to 16.2 1.18 DW-6

Manganese 50 of 52 BDL to 702 204 DW-15

Mercury 4 of 52 BDL to 0.22 0.55 DW-3

Silver 2 of 52 BDL to 1.0 0.14 SW-3

Zinc 23 of 52 BDL to 10,400 (J) 413 DW-25 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

Zinc was detected in several of the off-site bedrock monitoring wells with the maximum concentration of10,400 ug/L. Manganese detected in the on-site bedrock ground water showed a much wider distribution thanthe other site-specific inorganic constituents. The manganese distribution does not correlate well with othersite-specific inorganic constituents or VOCs that are considered to be associated with historical operations atthe facility.

The only manganese concentrations that exceeded 600 ug/L in the off-site bedrock ground water were insamples collected from DW-15, located north of the facility. The only other off-site bedrock ground watermonitoring wells in which the manganese concentrations exceeded 350 ug/L were DW-32, DW-28, DW-26,and DW-16. Two of these wells are located north of the facility, and two are located south of the facility.Based on evaluations of filtered and unfiltered samples, there does not appear to be a significant correlationbetween the concentration of manganese and level of turbidity in bedrock ground water.

Nine on-site and four off-site bedrock ground water samples from four on-site and one off-site bedrockmonitoring wells were analyzed for the remaining TAL inorganic constituents. Arsenic and cobalt were detectedin deep recovery well DR-1 located near the former solvent disposal area at concentrations up to 4.1 and 10.4ug/L, respectively.

6.2.2 Organic Compounds in Bedrock Ground Water

A total of 60 bedrock ground water samples, including background samples, collected from the onsite bedrockmonitoring wells were analyzed for TCL VOCs. The frequencies of detection, concentration ranges, and thelocations of the maximum concentrations of the dominant VOCs detected in the on-site bedrock ground waterare presented below in Table 7.


Page 20

TABLE 7 - SUMMARY OF VOCs IN ON-SITE BEDROCK GROUND WATER VOC

VOCFrequency of


Range Average 1

(ug/L)

Location of Maximum

Concentration

Tetrachloroethene 16 of 60 BDL to 870 35.5 DR-1

Trichloroethene 39 of 60 BDL to 30,000 3,520 DW-1

1,1,1-Trichloroethane 31 of 60 BDL to 28,000 1,430 DR-1

1,1,2-Trichloroethane 6 of 60 BDL to 25 1.10 DW-20

1,2-Dichloroethene 30 of 60 BDL to 19,000 988 DR-1

1,1-Dichloroethene 35 of 60 BDL to 7,200 460 DR-1

1,2-Dichloroethane 7 of 60 BDL to 11 0.88 DW-20


Methylene Chloride 113 of 60 BDL to 1000 44.9 DR-1

Acetone 4 of 60 BDL to 510 11.65 DR-1

Toluene 8 of 60 BDL to 2,800 130 DR-11 Average concentration calculations used one-half the detection limit for all values reported as BDL.

In addition, a total of 60 bedrock ground water samples, including background samples, were collected fromthe off-site bedrock monitoring wells and analyzed for TCL VOCs. The frequencies of detection, concentrationranges, and the locations of the maximum concentrations of the dominant VOCs detected in the off-sitebedrock ground water are presented below in Table 8.

A wide range of concentrations was detected for several VOCs in the bedrock ground water at the Site. TheVOC plume in the bedrock ground water closely mirrors the shape and concentrations of the VOC plume inthe shallow ground water. The RI data indicates the source of the shallow and bedrock ground water plumes,as well as the general ground water flow directions on the Site, are the same.

The dominant VOC in the bedrock ground water at the Site, based on frequencies of detection andconcentrations, was trichloroethene (TCE). The TCE plume in the bedrock ground water extends in a generalnorth/south direction at the Site. One of the source areas for the TCE plume, and the other VOCs at the Site, isthe former solvent disposal area located just south of Building #4. This area was used for the disposal of spentsolvents prior to 1980. The TCE plume extends approximately 1,100 feet to the north, and approximately2,200 feet to the south, from the former solvent disposal area.


Page 21

TABLE 8 - SUMMARY OF VOCs IN OFF-SITE BEDROCK GROUND WATER VOC

VOCFrequency of


Range Average 1

(ug/L)

Location of Maximum

Concentration

Tetrachloroethene 13 of 60 BDL to 33 2.88 DW-3

Trichloroethene 41 of 60 BDL to 1,800 149 DW-3

1,1,1-Trichloroethane 18 of 60 BDL to 940 (J) 71.5 DW-3

1,1,2-Trichloroethane 9 of 60 BDL to 25 1.03 DW-3

1,2-Dichloroethene 25 of 60 BDL to 8 14.8 DW-29

1,1-Dichloroethene 24 of 60 BDL to 190 34.3 DW-3


1,1-Dichloroethane 15 of 60 BDL to 2 (J) 3.72 DW-14

Methylene Chloride 9 of 60 BDL to 32 1.30 DW-15 & 17

Acetone 11 of 60 BDL to 10 8.12 DW-6

Toluene 2 3 of 60 BDL to 2 (J) 0.46 DW-16 & 36 1 Average concentration calculations used one-half the detection limit for all values reported as BDL. 2 Exclusive of packer test results

Higher TCE concentrations were detected in on-site monitoring wells DW-1 (16,000 ug/L) and DW-22(16,000 ug/L) located south of the former solvent disposal area. The higher TCE concentrations in the off-sitebedrock ground water were detected in the wells located immediately north of the facility (i.e., DW-2, DW-3,and DW-14). TCE concentrations in these wells ranged from 130 ug/L to 1,800 ug/L.

The concentration distributions of the other chlorinated ethanes and ethenes were very limited and somewhatdiscontinuous in extent. The 1,2-DCE distribution is similar to that of TCE; however, the concentrations arelower. Vinyl chloride was reported in bedrock ground water monitoring well DW-17(B) at 6 ug/L, and inDW-7 at 3 ug/L. Chloroethane was detected in three bedrock ground water monitoring well at a maximumconcentration of 3 ug/L.

Methylene chloride was detected on two occasions in bedrock ground water recovery well DR-1 at elevatedconcentrations (1,000 ug/L in April 1996 and 710 ug/L in July 1996). Chloroform was detected in on-sitebedrock ground water monitoring wells at concentrations up to 14 ug/L. Chloroform was detected in off-sitebedrock ground water monitoring wells in 11 samples at concentrations up to 15 ug/L.


Page 22

Three chlorinated ethanes (1,1,2,2-tetrachloroethane; 1,1,2-trichloroethane; and 1,2-dichloroethane) weredetected in several samples, typically at cumulative concentrations of less than 10 ug/L. However,1,1,2-trichloroethane and 1,2-dichloroethane were detected at 25 and 11 ug/L, respectively in DW-20 inNovember 1998.

Tetrachloroethene (PCE) and 1,1-dichloroethene (1,1-DCE) were observed to have similar distributions in thebedrock ground water. These compounds are present in most of the samples in which TCE, 1,1,1-TCA, and1,2-DCE are present. The higher concentrations of 1,1-DCE were reported in wells located in the vicinity ofthe former solvent disposal area. The higher concentrations of PCE also were reported in this same area, aswell as in DW-20. The distribution of 1,1-DCE approximates the distribution of TCE, although at lowerconcentrations. This distribution indicates that the source of these chlorinated VOCs is the same and thetransport mechanisms are similar.

Non-halogenated VOCs including ketones, such as acetone and methyl ethyl ketone, were detectedsporadically in the bedrock ground water. With the exception of a single detection of 2-butanone (MEK),acetone was the only ketone detected in the bedrock ground water. Aromatic VOCs, including toluene,xylenes, benzene, ethyl benzene, and styrene, were reported in the on-site bedrock ground water. Amongthese, toluene has consistently been detected in deep recovery well DR-1, most recently at 1,700 ug/L.

Six different TCL SVOCs (two phthalate esters, three PAHs, and phenol) were detected in one or moreon-site bedrock ground water samples. DEHP was detected in four on-site bedrock ground water samples at amaximum concentration of 17 ug/L. No pesticides or PCBs were detected in any of the bedrock ground watersamples.

6.3 Summary of Private Well Ground Water Contamination

A private well survey was conducted during the OU2 RI within a 1/2-mile radius of the facility. A total of 14private wells were sampled as part of the RI. All of the off-site private wells were sampled on at least twoseparate occasions with analyses of cadmium, chromium, manganese, mercury, silver, zinc, and TCL VOCsbeing conducted on all samples. The frequencies of detection, concentration ranges, and locations of the maximum detected concentrations for the six site-specific inorganics in the off-site private wells are presentedbelow in Table 9.


Page 23

TABLE 9 - SUMMARY OF INORGANIC CONSTITUENTS IN OFF-SITE PRIVATE WELLS

Inorganic Compounds



Average 1


Concentration

Cadmium 14 of 68 BDL to 18.9 0.46 PW-20

Chromium 40 of 68 BDL to 68.1 3.90 PW-2

Manganese 54 of 68 BDL to 18,900 1,230 PW-5

Mercury 1 of 68 BDL to 0.58 0.071 PW-20

Silver 4 of 68 BDL to 6.4 0.24 PW-20

Zinc 60 of 68 BDL to 5,360 303 PW-20 1 Average concentration calculations used one-half the detection limit for all values reported as BDL.

Cadmium, chromium, mercury and silver detected at very low concentrations in the off-site private wellsamples. Manganese concentrations in the off-site private wells showed a much wider distribution than the othersite-specific inorganic constituents. The highest manganese concentration (18,900 ug/L) was detected in PW-5in the former REA Construction well; this sample concentration was an order of magnitude higher thanmanganese concentrations detected in any of the other private wells. Zinc was detected in several of the off-sitedeep private wells with the higher concentrations being detected in PW-20 and PW-6, both of which arelocated south of the facility. The cause for these anomalously high concentrations is not known.

A total of 117 ground water samples collected from the off-site private wells were analyzed for TCL VOCs.The frequencies of detection, concentration ranges, and the locations of the maximum concentrations of thedominant VOCs detected in the off-site private wells are presented in Table 10.


Page 24

TABLE 10 - SUMMARY OF VOCs IN OFF-SITE PRIVATE WELLS VOC

VOCFrequency of


Range Average 1

(ug/L)

Location of Maximum

Concentration

Tetrachloroethene 2 of 117 BDL to 0.1 0.022 PW-17

Trichloroethene 5 of 117 BDL to 0.9 0.34 PW-1

1,1,1-Trichloroethane 3 of 117 BDL to 7.6) 0.54 PW-5

1,2-Dichloroethene 5 of 117 BDL to 36.6 1.50 PW-5

1,1-Dichloroethene 4 of 117 BDL to 5.7 0.49 PW-5

1,2-Dichloroethane 1 of 117 BDL to 0.2 0.022 PW-3

1,1-Dichloroethane 3 of 117 BDL to 11 0.77 PW-5

Methylene Chloride 5 of 117 BDL to 17.3 0.94 PW-5

Acetone 18 of 117 BDL to 19 3.26 PW-18

Toluene 4 of 117 BDL to 14 0.57 PW-5

Vinyl Chloride 3 of 117 BDL to 18 1.38 PW-5

Benzene 10 of 117 BDL to 1790 76.6 PW-51 Average concentration calculations used one-half the detection limit for all values reported as BDL.

Low concentrations of certain VOCs were detected in the off-site private wells, including benzene in wellPW-5 (former REA Construction). SVOCs detected in wells prior to the OU2 RI/FS in the REA Constructionwell are most likely be associated with the asphalt operations at the facility. The REA site also was previouslyused as a coal gasification plant that typically used chlorinated VOCs and PAHs associated with its operation.Halogenated methane compounds, especially chloroform, were detected at low levels in the off-site privatewells.

7.0 CURRENT AND POTENTIAL FUTURE SITE AND RESOURCES USES

The current and reasonably anticipated future land uses for the facility and the land around the facility issummarized as follows;

i The facility is presently operating as a battery manufacturing plant;

i The land surrounding the facility is presently used for a variety of purposes, including commercial, lightindustrial, and residential;


Page 25

i The facility will continue to be a battery manufacturing plant into the foreseeable future. To ensureprotection of human health and the environment into the future, institutional controls such as deedrestrictions and/or restrictive covenants will be placed on the facility property, and potentially any otherproperty around the facility affected by the Site-related ground water contamination, to prohibit thefuture use of site-related ground water contamination;

i The reasonably anticipated future land use for the land around the facility will continue to becommercial, light industrial, and residential purposes. The potential beneficial ground water and surfacewater uses for future use assumptions (e.g., potential drinking water, recreational) are based onknowledge of current uses. Evaluating the current and future ground water use assumptions is a keyfactor in determining the importance of addressing Site-specific soil and sediment contamination withthe OU1 Remedial Action, and Site-specific ground water contamination with the OU2 RemedialAction.

8.0 SUMMARY OF SITE RISKS

A baseline risk assessment (BRA) was conducted as part of the Operable Unit Two RI/FS to determine thepotential current and future effects of contaminants on human health and the environment if no action were takento address the contaminated ground water at the Site. The BRA focused on potential health effects for both children and adults that could result from current or future exposure to the chemicals of concern in groundwater. The chemicals of concern (COCs) for an exposure scenario are the chemicals of potential concern(COPCs) that significantly contribute to an exposure pathway for an identified receptor. The Risk Assessment adds the risk from all COCs in order to assess the cumulative risk for each exposure scenario. A COC musthave an individual cumulative carcinogenic risk which exceeds 1 X 10-4 (i.e., one in ten thousand people woulddevelop cancer from long-term exposure), or a hazard index (HI) for noncarcinogenic risk (e.g., nervousdisorders) exceeding a value of 1.0. A cumulative carcinogenic risk level exceeding 1 X 10-4, or a HI valueexceeding 1.0 for noncarcinogenic risk, are typically used as "remediation triggers".

Exposure scenarios for both current and future land use were evaluated based on an estimate of ReasonableMaximum Exposure. Under the current land use scenario, unacceptable risks were identified for hypotheticalhuman receptors, including a child or adult resident living near the Site, who could ingest or come into contactwith Site-related contaminated ground water.

Under the future land use scenario, unacceptable risks were identified for hypothetical human receptors livingon or around the Site, including a child or adult resident, who could ingest or come into contact withSite-related ground water contamination.

8.1 IDENTIFICATION OF CHEMICALS OF CONCERN

The Site-related Chemicals of Concern (COCs) which contributed to unacceptable noncarcinogenic risk fromthe ingestion or dermal exposure of shallow on-site ground water include 1,1,1-trichloroethane,1,1,2-trichloroethane, 1,1-dichloroethane, 1,1-dichloroethene, 1,2-dichloroethane, 1,2-dichloroethene (total),1,3-dichloropropene, 1,2-dichloropropane, bromomethane, bromodichloromethane, chloroform,dichlorobromomethane, tetrachloroethene, trichloroethene, benzene, methylene chloride,


Page 26

1,1,2,2-tetrachloroethane, toluene, vinyl chloride, naphthalene, beta-BHC, dieldrin, aluminum, antimony,arsenic, barium, cadmium, chromium, copper, cyanide, iron, manganese, mercury, nickel, thallium, vanadium,and zinc. Table 11 shows the range of concentrations for each COC, the frequency of detection for each, andwhether the maximum concentration for each COC was identified in shallow or bedrock ground water.

Table 12 summarizes the exposure point concentration for each COC as well as the type of statistical measureit represents (note that 1E-2 equals 1 X 10-2). The statistical measure (the 95 percent confidence limit (UCL) ofthe arithmetic mean concentration for a chemical) is used as the exposure point concentration. However, forsites with limited amount of data or extreme variability in the data, the highest concentration (i.e., the maximumvalue) is used commonly as a default exposure point concentration.

8.2 SUMMARY OF EXPOSURE ASSESSMENT

The exposure assessment evaluates and identifies complete pathways of exposure to human populationspotentially living on or near the Site. Table 13 summarizes the exposure pathways evaluated during the OU2RI/FS (note that "QUAN" means quantitation limit). Current exposure scenarios evaluated for the site includethe ingestion, dermal contact, and inhalation of on- and off-site ground water. Potential receptors evaluated forthe current exposure scenarios include on-site construction workers and visitors to the facility. Potentialreceptors evaluated for the future exposure scenarios include both on-site and off-site child and adult residents.Future exposure scenarios consider the potential for construction of water supply wells within the ground watercontamination plume, as well as exposure to the site-related COCs resulting from the ingestion of, and dermalcontact with ground water, or inhalation of vapor from ground water.

8.3 SUMMARY OF TOXICITY ASSESSMENT

The purpose of the toxicity assessment is to assign dose-response toxicity values to each chemical evaluated inthe risk assessment. The toxicity values are used in combination with estimated doses to which a specific humanreceptor could be exposed to evaluate the potential human health risks associated with each chemical ofpotential concern (COPC).

Human health criteria developed by the EPA [cancer slope factors (CSF) and reference doses (RfD)] wereprimarily obtained from the Integrated Risk Information System (IRIS) web page (USEPA, 200la), or the 1997Health Effects Assessment Summary Tables (HEAST) (USEPA, 1997b). In some cases, documents fromEPA's National Center for Environmental Assessment (NCEA) were used to obtain criteria for chemicals thatwere not listed in IRIS or HEAST. When a chemical has no chronic toxicity values, the value of a chemical thatis related both chemically and lexicologically, is used. For example, the RfD for naphthalene is used for2-methylnaphthalene. When this occurs, it is indicated in the appropriate toxicity summary table.

In evaluating potential health risks, both carcinogenic and non-carcinogenic health effects must be considered.The potential for producing carcinogenic effects is limited to substances that have been shown to be actual orprobable carcinogenic in animals and/or humans. Excessive exposure to all substances, carcinogens andnon-carcinogens, can produce adverse non-carcinogenic effects. Therefore, it is necessary to identifynon-carcinogenic toxicity criteria, which establish non-carcinogenic dose-responses, for every chemicalselected as a COPC, regardless of its cancer classification, and to identify carcinogenic toxicity criteria, whichestablish carcinogenic dose-responses, for chemicals that are classified as carcinogens.


Page 27

TABLE 11 - SUMMARY OF SITE-SPECIFIC CHEMICALS OF CONCERN


Page 28

TABLE 12 - SUMMARY OF SITE-SPECIFIC EXPOSURE POINT CONCENTRATIONS


Page 29

TABLE 13 - SUMMARY OF SITE-SPECIFIC EXPOSURE PATHWAYS


Page 30

TABLE 13 (con’t) - SUMMARY OF SITE-SPECIFIC EXPOSURE PATHWAYS


Page 31

Toxicity criteria used to evaluate potential non-carcinogenic health effects are termed reference doses (RfDs). Itis assumed in developing RfDs that a threshold dose exists below which there is no potential for human toxicity.The term RfD was developed by the EPA to refer to the daily intake of a chemical to which an individual canbe exposed without any expectation of non-carcinogenic effects (i.e., organ damage, biochemical alterations,birth defects) occurring during a given exposure period. Reference doses (RfDs) are typically expressed asmass of chemical (mg) per mass of the receptor (kg) per unit of time (day), with the resulting units ofmg/kg/day.

8.4 RISK CHARACTERIZATION

A risk characterization is an evaluation of the nature and degree of potential carcinogenic and non-carcinogenic health risks posed to current and hypothetical future receptors at a location, in this case ground water at theSite. The objective of the risk characterization is to integrate the exposure and toxicity assessments intoquantitative and qualitative expressions of risk. Human health risks for carcinogenic and non-carcinogeniceffects are discussed independently because of the different toxicological endpoints, relevant exposuredurations, and methods employed in characterizing risk. The potential for carcinogenic effects is limited to onlythose chemicals classified as carcinogens, whereas both carcinogenic and non-carcinogenic chemicals areevaluated for potential non-carcinogenic effects.

Non-carcinogenic and carcinogenic risks were evaluated for each exposure pathway and scenario byintegrating the exposure doses with the toxicity criteria for the chemicals of potential concern. Exposure pointconcentrations were calculated for the reasonable maximum exposure scenarios in shallow and bedrock groundwater.

For carcinogens, risks are generally expressed as the incremental probability of an individual's developingcancer over a lifetime of exposure to the carcinogen.

The incremental risk of developing cancer from exposure to a chemical at the Site is defined as the additionalprobability that an exposed individual (i.e., receptor) will develop cancer during his or her lifetime (assumed tobe 70 years). This value is calculated from the average daily intake over a lifetime (GDI) expressed as mg ofCOPC/kg body weight/day and the cancer slope factor (CSF) for the chemical of potential concern as follows(USEPA, 1989a):

Risk = GDI x CSF

When the product of GDI x CSF is greater than 0.1, this expression may be estimated as:

Risk = 1 - exp(-CDI x CSF)

where:

Risk = Additional Cancer Risk (unitless) GDI = Daily Intake (mg/kg-day) CSF = Cancer Slope Factor (mg/kg-day)-1


Page 32

These risks are probabilities that usually are expressed in scientific notation (e.g., 1 X 10-6). An excess lifetimecancer risk of 1X 10-6 indicates that an individual experiencing the reasonable maximum exposure estimate hasa 1 in 1,000,000 chance of developing cancer as a result of site-related exposure. This is referred to an "excesslifetime cancer risk" because it would be in addition to the risks of cancer individuals face from other causessuch as smoking or exposure to too sun. The chance of an individual's developing cancer from all other causeshas been estimated to be as high as one in three. EPA's generally acceptable risk range for site-relatedexposures is 10-4 to 10-6.

8.4.1 SUMMARY OF CARCINOGENIC RISK

Unacceptable carcinogenic risk exceeding 1 X 10-4 was identified during the BRA from hypothetical exposureto site-related COCs in ground water. The total carcinogenic risk to the hypothetical future child and adultresidents living on-site from exposure to COCs in shallow ground water is

8.1 X 10-2, mainly due to the potential ingestion of 1,1-dichloroethene, trichloroethene, and 1,1,2,2- tetrachloroethane. The total carcinogenic risk for hypothetical future child and adult residents living on-site frompotential exposure to COCs in bedrock ground water is 8.4 X 10-2.

8.4.1.1 Exposure to Shallow Ground Water

For reasonable maximum intake factors and exposure point concentrations the total increased cancer riskacross all exposure routes for hypothetical future on-site adult residents who are exposed to shallow groundwater is 5.1 X 10-2. The total increased cancer risk due to the ingestion route is calculated as 4.2 X 10-2. Thetotal increased cancer risk due to combined inhalation exposure routes is calculated as 1.7 X 10-3. The totalincreased cancer risk due to combined dermal exposure routes is calculated as 7.1 X 10-3.

The total increased cancer risk across all exposure routes for hypothetical future on-site child residents who areexposed to shallow ground water is 3.1 X 10-2. The total increased cancer risk due to combined inhalationexposure routes is calculated as 1.7 X 10-3. The total increased cancer risk due to combined dermal exposureroutes is calculated as 4.5 X 10-3, and the total cancer risk due to the ingestion route if 2.4 X 10-2.

The total increased cancer risk across all exposure routes for current or future off-site adult residents who areexposed to shallow ground water is 1.1 X 10-3. The increased cancer risk due to ingestion of drinking water iscalculated as 8.8 X 10-4 while the total increased cancer risk due to combined inhalation exposure routes iscalculated as 3.8 X 10-5. The total increased cancer risk due to combined dermal exposure routes is calculatedas 1.4 X 10-4.

The total increased cancer risk across all exposure routes for current or future off-site child residents who areexposed to shallow ground water is 6.4 X 10-4. The increased cancer risk due to ingestion of drinking water iscalculated as 5.1 X 10-4. The total increased cancer risk due to combined inhalation exposure route is 3.7 X10-5, while the total cancer risk due to combined dermal exposure is 9.4 X 10-5.


Page 33

8.4.1.2 Exposure to Bedrock Ground Water

The total increased cancer risk across all exposure routes for hypothetical future on-site adult residents who areexposed to bedrock ground water is 5.3 X 10-2. The increased cancer risk due to ingestion of drinking water iscalculated as 4.4 X 10-2, primarily due to ingestion of 1,1-dichloroethene and trichloroethene. The totalincreased cancer risk due to combined inhalation exposure routes is calculated as 1.1 X 10-3, and the totalincreased cancer risk due to combined dermal exposure routes is calculated as 8.1 X 10-3.

For reasonable maximum intake factors and exposure point concentrations the total increased cancer riskacross all exposure routes for hypothetical future on-site child residents who are exposed to bedrock groundwater is 3.2 X 10-2. The increased cancer risk due to ingestion of drinking water is calculated as 2.6 X 10-2,primarily due to ingestion of 1,1-dichloroethene and trichloroethene.

The total increased cancer risk due to combined inhalation exposure routes is calculated as 1.2 X 10-3, and thetotal increased cancer risk due to combined dermal exposure routes is calculated as5.2 X 10-3.

The total increased cancer risk across all exposure routes for current or future off-site adult residents who areexposed to bedrock ground water is 2.2 X 10-4. The increased cancer risk due to ingestion of drinking water iscalculated as 1.8 X 10-4. The total increased cancer risk across all exposure routes for current or future off-sitechild residents who are exposed to bedrock ground water is 1.3 X 10-4. The increased cancer risk due toingestion of drinking water is calculated as 1.1 X 10-4.

Table 14 summarizes the carcinogenic risks associated with child and adult residents resulting from exposure toon-site shallow and bedrock ground water. Table 15 summarizes the carcinogenic risks associated with childand adult residents resulting from exposure to off-site shallow and bedrock ground water.

8.4.2 SUMMARY OF NON-CARCINOGENIC RISK

The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a specified timeperiod (e.g., life-time) with a reference dose (RfD) derived for a similar exposure period. An RfD represents alevel that an individual may be exposed to that is not expected to cause any deleterious effect. The ratio ofexposure to toxicity is called a hazard quotient (HQ). An HQ 1 indicates that site-related exposures maypresent a risk to human health. The following sections summarize the unacceptable non-carcinogenic riskresulting from hypothetical exposure to Site-related COCs in ground water.


Page 34

TABLE 14 - RISK CHARACTERIZATION SUMMARY - CARCINOGENS IN ON-SITEGROUND WATER

Carcinogenic Risk

ExposureMedium

ExposureScenario

Ingestion DermalContact

Inhalation ExposureRoute Total

ShallowGround Water

On-Site ChildResident

2.4 X 10-2 4.5 X 10-3 1.7 X 10-3 3.1 X 10-2

On-Site AdultResident

4.2 X 10-2 7.1 X 10-3 1.7 X 10-3 5.1 X 10-2

BedrockGround Water


2.6 X 10-2 5.2 X 10-3 1.2 X 10-3 3.2 X 10-2


4.4 X 10-2 8.1 X 10-3 1.1 X 10-3 5.3 X 10-2

TABLE 15 - RISK CHARACTERIZATION SUMMARY - CARCINOGENS IN OFF-SITEGROUND WATER

Carcinogenic Risk

ExposureMedium

ExposureScenario



ShallowGround Water


5.1 X 10-4 9.4 X 10-5 3.7 X 10-5 6.4 X 10-4


8.8 X 10-4 1.4 X 10-4 3.8 X 10-5 1.1 X 10-3

BedrockGround Water


1.1 X 10-4 1.9 X 10-5 5.8 X 10-6 1.3 X 10-4


8.8 X 10-4 3.0 X 10-5 5.7 X 10-6 2.2 X 10-4

8.4.2.1 Exposure to Shallow Ground Water

The total HI across all exposure routes for hypothetical future on-site child residents who are exposed toshallow ground water is 2,700. The HI due to ingestion of drinking water is calculated as 2,300, and the HI dueto all inhalation exposure routes is calculated as 130, The combined dermal exposure risk from swimming andbathing is calculated as 370.


Page 35

The total HI across all exposure routes for hypothetical future on-site adult residents who are exposed toshallow ground water is 1,100. The HI due to ingestion of drinking water is calculated as 980, primarily due toingestion of trichloroethene (HQ = 780) and chromium (HQ = 120). The HI due to all inhalation exposureroutes is calculated as 33, while the combined dermal exposure risk is calculated as 140.

The total HI across all exposure routes for current or future off-site adult residents who are exposed to shallowground water is 13. The HI due to ingestion of drinking water is calculated as 11, and the combined dermalexposure risk is calculated as 1.3.

The total HI across all exposure routes for current or future off-site child residents is 30. The HI due toingestion of drinking water is calculated as 26, primarily due to ingestion of trichloroethene (HQ= 17). Thecombined dermal exposure risk is calculated as 3.4.

8.4.2.2 Exposure to Bedrock Ground Water

The total HI across all exposure routes for hypothetical future on-site adult residents who are exposed tobedrock ground water is 300. The HI due to ingestion of drinking water is calculated as 270, primarily due toingestion of trichloroethene with an HQ = 140. The combined dermal exposure risk is calculated as 39.

The total HI across all exposure routes for hypothetical future on-site child residents who are exposed tobedrock ground water is 730. The HI due to ingestion of drinking water is calculated as 630, primarily due toingestion of 1,1,1-trichloroethane (HQ= 90), 1,1-dichloroethene (HQ= 51), 1,2-dichloroethene (total) (HQ=140), and trichloroethene (HQ= 320). The HI due to all inhalation exposure routes is calculated as 1.6, whilethe combined dermal exposure risk is calculated as 100.

Table 16 summarizes the non-carcinogenic risks associated with child and adult residents resulting fromexposure to on-site shallow and bedrock ground water. Table 17 summarizes the non-carcinogenic risksassociated with child and adult residents resulting from exposure to off-site shallow and bedrock ground water.

The total HI across all exposure routes for current and future off-site adult residents who are exposed tobedrock ground water is 2.8, mainly due to the ingestion of drinking water (HQ = 2.21). The total HI across allexposure routes for current and future off-site child residents who are exposed to bedrock ground water is 7.4.The HI due to ingestion of drinking water is calculated as 5.1. The HI due to all inhalation exposure routes iscalculated as 1.0.


Page 36

TABLE 16 - RISK CHARACTERIZATION SUMMARY - NON-CARCINOGENS IN ON-SITEGROUND WATER

Non-Carcinogenic Risk - HI Values

ExposureMedium

ExposureScenario



ShallowGround Water


2,300 370 130 2,700


980 140 33 1,100

BedrockGround Water


630 100 1.6 730


270 39 0.40 300

TABLE 17 - RISK CHARACTERIZATION SUMMARY - NON-CARCINOGENS IN OFF-SITEGROUND WATER

Non-Carcinogenic Risk - HI Values

ExposureMedium

ExposureScenario



ShallowGround Water


26 3.4 0.84 30


11 1.3 0.21 13

BedrockGround Water


5.1 0.35 1.0 7.4


2.21 0.14 0.26 2.8

8.5 UNCERTAINTIES ASSOCIATED WITH RISK CHARACTERIZATION Each complete exposure pathway involves more than one chemical. For purposes of a human health riskassessment, cancer risks or hazard quotients are considered additive (i.e., summed) for multiple chemicalsconsidered in a single exposure pathway. Uncertainties associated with summing risks or hazard quotients formultiple substances are of concern in the risk characterization component of the Baseline Human Health RiskAssessment. The assumption ignores the possibility of synergistic or antagonistic activities in the metabolism ofthe various chemicals. This could result in over- or under-estimation of risk.


Page 37

9.0 REMEDIATION OBJECTIVES

This section contains the site-specific Remedial Goals (RGs) for the COCs and media of concern (i.e., shallowand bedrock ground water) at the Site. Based on the unacceptable levels of risk summarized in the RiskCharacterization section of this ROD, specific RGs are required to specify the clean-up levels for Site-relatedground water contaminants. These levels are based on Federal and/or State drinking water standards.

RGs were developed for all of the exposure scenarios that have a total cancer risk exceeding 1.0 X 10-4.Individual COCs contributing cancer risks to these scenarios had RGs if their individual cancer risk was greaterthan 1 X 10-6. The objective of the selected remedy is to reduce the Site-related COCs to meet MCLs orapplicable State ground water standards, and reduce total carcinogenic risks to the risk-based level of 1 X 10-4

for future residential ground water use.

RGs based on non-carcinogenic risk were developed for all site-related exposure scenarios that have a totalHazard Index exceeding 1.0. Individual COCs contributing hazards to these scenarios had RGs if their hazardquotient was greater than or equal to 0.1. The selected remedy will restore the site-related ground water fordrinking water and other beneficial purposes by reducing all Site-related COCs to below MCLs or applicableState ground water standards, and reduce total non-carcinogenic risks to a Hazard Index less than 1.0.

RGs will be met through the implementation of the selected remedy that consists of both containment (groundwater pump-and-treat) and institutional controls. In addition, technology evaluations will be conducted todetermine the feasibility of enhancing this final remedy, both in the source area on the facility property, and inthe areas off the facility property where site-related ground water contamination is known to exist. The RGs arerequired to ensure the remedy is protective of human health and the environment

The specific Remedial Action Objectives (RAOs) to meet these RGs are summarized as follows:

Restore aquifer ground water by reducing all COCs to below MCLs and/or State ground water standards, a 1X 10-4 total carcinogenic risk for future residential ground water use, and an HI less than 1.0 for totalnon-carcinogenic risk.

Contain Site-related ground water contamination such that COC migration off the facility property does notresult in total carcinogenic risk greater than 1 X 10-4, and/or a total non-carcinogenic risk with HI greater than1.0.

Contain Site-related ground water contamination on the facility property such that ground water discharge tosurface waters on and off the facility property does not exceed a 1 X 10-4 total carcinogenic risk, and a total HIless than 1.0.

Conduct innovative technology evaluations (such as in-situ bioremediation, in-situ chemical oxidation,electrochemical techniques, and monitored natural attenuation) during the OU2 Remedial Design to determine ifthese technologies, singly, or in combination with the selected remedy, can enhance remediation and possiblyreduce the overall remediation timeframe and cost.


Page 38

Maintain institutional controls to ensure future access to and use of the areas with Site-related ground watercontamination prevents exposure to carcinogenic COCs at levels greater than 1X 10-4, and to non-carcinogenicCOCs at levels with HI values greater than 1.0.

10.0 DESCRIPTION OF REMEDIAL ALTERNATIVES

The most appropriate technologies were combined in various ways to present a range of potential remedialapproaches that address the RAOs for OU2. To the extent appropriate, these remedial technologies includeinstitutional controls, containment, ground water extraction and treatment, in-situ ground water treatment of thesource areas, and monitored natural attenuation to mitigate conditions of potential concern. The general range ofremedial alternatives considered is based on USEPA guidance for Feasibilit

epa superfund record of decisionsep 30, 2002 · the duracell facility currently consists of three...

Documents