SITE 4B: GROUNDWATER & SOIL FINAL RECORD OF ...SDMS DocID 2107378 % \ FINAL RECORD OF DECISION SITE...

$Page 1: SITE 4B: GROUNDWATER & SOIL FINAL RECORD OF ...SDMS DocID 2107378 % \ FINAL RECORD OF DECISION SITE 4B: GROUNDWATER AND SOIL Operable Unit 14 at the ALLEGANY BALLISTICS LABORATORY$
SDMS DocID 2107378

% \

FINAL RECORD OF DECISION

SITE 4B: GROUNDWATER AND SOIL Operable Unit 14

at the

ALLEGANY BALLISTICS LABORATORY ROCKET CENTER, WEST VIRGINIA

October 2007

Contents

Contents iii

Acronyms v

1 Declaration ; 1-1 1.1 Site Name and Location 1-1 1.2 Statement of Basis and Purpose 1-1 1.3 Description of Selected Remedy ; ; 1-1 1.4 Statutory Determinations 1-1 1.5 Authorizing Signatures 1-2

2 Decision Summary 2-1 2.1 Site Name, Location, and Description 2-1 2.2 Site History and Eriforcement Activities ......2-1

2.2.1 Site History 2-1 2.2.2 Previous Investigations 2-2 2.2.3 CERCLA Enforcement Activities 2-5

2.3 Community Participation 2-5 2.4 Scope and Role of Operable Unit or Response Action '.: 2-6 2.5 Site Characteristics 2-7

2.5.1 Site Overview 2-7 2.5.2 Sampling Strategy 2-7 2.5.3 Source of Contamination 2-7 2.5.4 Nature and Extent of Chemicals in Site 4B Groundwater and Soil 2-8 2.5.5 Surface Soil 2-8 2.5.6 Subsurface Soil 2-8 2.5.7 Groundwater 2-9

2.6 Current and Potential Future Site and Resource Uses 2-10 2.6.1 Current Site Uses 2-10 2.6.2 Potential Future Site Uses 2-10

2.7 Summary of Site Risks 2-10 2.7.1 Summary of Human Health Risk Assessment 2-11 2.7.2 Summary of Ecological Risk Assessment 2-12 2.7.3 Selected Remedy ; 2-13

2.8 Documentation of Significant Changes 2-13

3 Responsiveness Summary 3-1 3.1 Stakeholder Issues and Lead Agency Responses 3-1

4 References 4-1

RECORD OF DECISION, SITE 4B-GR0UNDWATER AND SOIL OPERABLE UNIT 14

Tables (located at the end of Section 2)

2-1 Preliminary Remediation Goals 2-2 Summary of COPCs for the HHRA 2-3 Risk Summary by Media and Receptor - 1996 Phase II RI 2-4 Summary of COPCs - Field Investigation Sampling (May -June 2000) 2-5 Mean Soil Concentrations - Site 4B Pilot Study

Figures (located at the end of Section 2)

2-1 Facility and Site Location Map 2-2 Former Site Layout 2-3 Historical Sampling Locations 2-4 Confirmatory Sample Locations and Areas of Excavation 2-5 Exposure Model for Site 4B

Appendixes

A Public Meeting Notice

B Public Meeting Transcript

Acronyms

ABL Allegany Ballistics Laboratory ATK Alliant Techsystems, Inc.

CERCLA Comprehensive Environmerital Response, Compensation and Liability Act COPC constituent of potential concern CRP Community Relations Plan CS Confirmation Study

ERA Ecological Risk Assessment ERN Environmental Restoration, Navy

FFA Federal Facilities Agreement ft foot/feet

HHRA Human Health Risk Assessment HI Hazard Index HQ Hazard Quotient

IAS Initial Assessment Study

IRP Installation Restoration Program

LTM long-term monitoring

MCL Maximum Contaminant Level mg/kg milligrams per kilogram MNA monitored natural attenuation NACIP Navy Assessment and Control of Installation Pollutants Navy United States Navy NCP National Oil and Hazardous Substances Pollution Contingency Plan NFA no further action NPL National Priorities List

OU operable unit

ppb parts per billion PRAP Proposed Remedial Action Plan PRG preliminary remediation goal

RAB Restoration Advisory Board RBC risk-based concentration RI Remedial Investigation ROD Record of Decision

SARA Superfund Amendments and Reauthorization Act SMP Site Management Plan

RECORD OF DECISION, SITE 4&-GR0UNDWATER AND SOIL OPERABLE UNIT 14

SSL soil screening level SVOC semivolatile organic compound

TAL Total Analyte List TCE trichloroethene TCL Total Compound List TRC Technical Review Committee

U.S. United States

USEPA United States Environmental Protection Agency

VOC volatile organic compound

WVDEP West Virginia Department of Environmental Protection

XRF x-ray fluorescence

SECTION 1

Declaration

1.1 Site Name and Location Site 4B: Groundwater and Soil (Operable Unit 14) Allegany Ballistics Laboratory (ABL), Rocket Center, West Virginia National Superfund Database Identification Number: WV0170023691

1.2 Statement of Basis and Purpose This decision document presents the selected remedy for Site 4B at ABL in Rocket Center, West Virginia (the site, or Site 4B). The final selected remedy was chosen in accordance with the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), and to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is based on the Administrative Record file for this site. The State of West Virginia concurs with the selected remedy.

1.3 Description of Selected Remedy The Urvited States (U.S.) Navy (Navy), as lead agency for CERCLA activities at ABL and the U.S. Environmental Protection Agency (USEPA), with the concurrence of the West Virginia Department of Environmental Protection (WVDEP), have determined that r\o further action (NFA) is necessary for the soil and groundwater at Site 4B. This decision is based on a soil removal conducted as part of a pilot study (CH2M HILL, 2006a) as well as the results of the associated human health and ecological risk assessments. These risk assessments determined that there are no unacceptable current or potential future risks associated with soil and groundwater attributable to Site 4B.

1.4 Statutory Determinations No remedial action is necessary at Site 4B to ensure the protection of human health and the environment. The selected remedy for Site 4B will not result in hazardous substances, pollutants, or contaminants existing at the site above levels that allow for unlimited use and unrestricted exposure; consequently, five-year reviews will not be required for this remedy.


1.5 Authorizing Signatures

Da^fti W. Anderson Date Director Installations and Equipment Office, by direction of Commander Naval Sea Systems Command

Jar/es 1/Burkef Dj/ector Date Hazardous Site Cleanup Division USEPA, Region III

The State of West Virginia has reviewed this Record of Decision (ROD) and the materials on which it is based and concurs with the selected remedy.

Ken Ellison, Director Date Division of Wasly Mdiiageiiitiiil WVDEP / - ^ ^ ^ £xsrf-TCri.-)4Wj

1-2

SECTION 2

Decision Summary

2.1 Site Name, Location, and Description Site 4B: Groundwater and Soil (Operable Unit 14) Allegany Ballistics Laboratory, Rocket Center, West Virginia National Superfund Database Identification Number: WV0170023691 Lead Agency: Department of the Navy Source of investigation funds: Environmental Restoration, Navy (ERN)

ABL is a research, development, and production facility located in Rocket Center, West Virginia, in the northem part of Mineral County. The facility is situated along a reach of the North Branch Potomac River, separating West Virginia and Maryland. The facility consists of two plants. Plant 1, owned by the Navy and operated by Alliant Techsystems, Inc. (ATK), occupies approximately 1,577 acres, of which about 400 acres are within the developed floodplain of the North Branch Potomac River. The remaining acreage is primarily forested and mountainous. Plant 2, a 57-acre facility adjacent to Plant 1, is owned and operated by ATK.

In June 1993, USEPA proposed the Plant 1 portion of the ABL facility for inclusion on the National Priorities List (NPL). The Plant 1 portion of ABL was added to the NPL as ; documented in the Federal Register, Volume 59, Number 27989, on May 31,1994. Figure 2-1 shows the location of ABL (comprising Plant 1 and Plant 2) and the approximate locations of its CERCLA sites. Plant 2 is not listed on the NPL, nor does it contain any CERCLA sites.

Site 4B is situated in the southeastem portion of Plant 1 at ABL, approximately 3,000 feet (ft) from the North Branch Potomac River (Figure 2-1). The groundwater and soil at Site 4B are defined as Operable Unit (OU) 14 and are addressed by this ROD..

2.2 Site History and Enforcement Activities

2.2.1 Site History Site 4B comprises the area adjacent to the southeast corner of Building 181 (Figure 2-2) where spent photographic and X-ray developing solutions (containing silver, cyanide, and phenols) were discharged through a hose, into a concrete drainage channel, and then underground into a pipe constiucted of terra cotta and steel. This pipe extended from the end of the concrete drainage channel to an open stormwater drainage ditch in an adjacent, grassy area (CH2M HILL, 2001). Several small, unvegetated gravel areas were also located within the grassy area. The drain entered a small ditch, approximately 2 ft wide and 1 ft deep, northeast of the building, as shown on Figure 2-2. This ditch collected stormwater runoff and did not typically contain standing water except during and after periods of significant precipitation. The ditch drained stormwater from the area into a larger ditch near

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the eastem perimeter of ABL and ultimately into the North Branch Potomac River (CH2M HILL, 1996b).

2.2.2 Previous Investigations Site 4B was part of a number of environmental investigations conducted at ABL in the mid-1980s and 1990s; Site 4B was also part of a supplemental soil investigation in 2000, as well as pilot study activities between 2002 and 2005. Investigations that included Site 4B are summarized below. Figure 2-3 shows historical sampling locations.

Initial Assessment Study/Confirmation Study (1983 through 1987)

The Initial Assessment Study (IAS), performed at ABL in 1983 under the Navy Assessment and Control of Installation Pollutants (NACIP) program, identified sites that posed a potential threat to human health or the environment as a result of former hazardous materials handling and operations (ES&E, 1983), based on a review of historical records. Site 4B was identified during the IAS, which concluded that this site did not pose an immediate threat; however, a Confirmation Study (CS) was recommended and conducted at the site to assess potential contamination. The CS, initiated in Jime 1984 and completed in August 1987, focused on identifying the existence, concentration, and extent of contamination.

Soil sampling at Site 4B was first performed in the CS, during which two soil samples were collected and analyzed for silver. In October 1984, two soil samples were collected from the drainage ditch northeast of Building 181, and the silver concentrations detected were 8,512 milligrams per kilogram (mg/kg) and 12,800 mg/kg. In March 1986, eight soil samples were collected at depths of 0 to 1 ft and from 1 to 2 ft at four locations near the drainage ditch and analyzed for total silver. Concentiations of silver in these samples ranged from 10.1 mg/kg to 122 mg/kg (Weston, 1989). One alluvial monitoring well (4GW01) was installed in 1985, and one bedrock monitoring well (3GW04) was installed in 1987; both wells were sampled as part of the CS. Volatile organic compounds (VOCs) and chlorinated solvent breakdown products were detected in the alluvial well (4GW01). Silver, however, was not detected in the alluvial groundwater. Low concentiations of tiichloroethene (TCE) and toluene, at 1 part per billion (ppb) each, were detected in the bedrock well.

As a result of SARA, the Navy changed its NACIP terminology and scope under the Installation Restoration Program (IRP) to follow the rules, regulations, guidelines, and criteria established by the USEPA for the Superfund program. Accordingly, the results of the CS are docurnented in an Interim Remedial Investigation (RI) Report, which recommended further remedial investigation for some sites and additional minimal investigation activities for Site 4B (Weston, 1989). This report concluded that the presence of silver in soil was related to disposal of X-ray solutions and that the presence of VOCs was associated with other plant activities.

Remedial Investigation (1992) and NPL Listing

Based on the recommendations of the Interim RI Report (Weston, 1989) and in accordance with the Navy's modified IRP policy, an Rl (CH2M HILL, 1996a) was performed following USEPA RI/FS format under CERCLA (USEPA, 1988). Although no soil samples were collected at Site 4B, groundwater sampling revealed VOCs (methylene chloride and toluene at 1 ppb in 3GW04, and methylene chloride at 1 ppb in 4GW01) at levels below Federal

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SECTION 2-DECISION SUMMARY

maximum contaminant levels (MCLs) and USEPA Region III tap-water risk-based concentiations (RBCs).

In June 1993, USEPA proposed the Plant 1 portion of the ABL facility for inclusion'on the NPL based on the calculated potential risks to human health and the environment. The Plant 1 portion of ABL was added to the NPL on May 31,1994 (see 59 Federal Register 27989).

Phase II Remedial Investigation (1994)

In 1994, a Phase II RI was conducted to further define the nature and extent of contamination at several ABL sites, including Site 4B (CH2M HILL, 1996b). During this investigation, baseline human health and ecological risk assessments were performed to evaluate potential risks posed by each site. Because photographic solutions containing cyanide and phenols were reportedly discharged from the southeast corner of Building 181, surface and subsurface soil samples were collected and analyzed for these compounds, as well as other constituents, during the Phase II RI. One surface and one subsurface soil sample (S4-3S/3) were collected from a location near the discharge pipe adjacent to Building 181 and analyzed for target compound list (TCL) VOCs, semivolatile organic compounds (SVOCs), target analyte list (TAL) inorganics, and cyanide. Two surface soil samples were collected from the drainage ditch: one (S4-1) from where the underground pipe discharged to the drainage ditch, and the other (S4-2) approximately 50 ft downgradient of the sample near the underground pipe. These samples were analyzed for TAL inorganics and' cyanide. Cyanide and phenols were not detected in any soil samples collected. The downgradient bedrock well (3GW04) contained a low concentiation of acetone at 15 ppb, which is two orders of magnitude below the USEPA Region III tap-water RBC, but also contained slightly elevated concentiations of arsenic and silver, above background levels. The down gradient alluvial well (4GW01) was analyzed for cyanide, which was not detected (CH2M HILL, 1996b).

The human health risk assessment (HHRA) indicated a potentially unacceptable hazard to a hypothetical future child resident from exposure to silver in soil, and potentially unacceptable hazards to hypothetical future adult and child residents from ingestion of manganese in groundwater. The ecological risk assessment (ERA) indicated there were potentially unacceptable risks to ecological receptors associated with contamination in soil, primarily associated with silver (CH2M HILL, 1996b).

Additional Characterization

Subsequent to the Phase II Rl, it was determined that additional soil sampling was required at Site 4B to further evaluate the potential impacts to soil from the discharge of spent photographic solutions and to provide sufficient additional data to aid in the development , of preliminary remediation goals (PRGs). Consequently, in June 2000,14 soil samples (AS04B-SB01 through AS04B-SB14) were collected along the drainage ditch on the southeastem side of Building 181 where the spent solutions were discharged from the building (Figure 2-3).

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XRF Pilot Study

The purpose of the X-ray fluorescence (XRF) pilot study was to evaluate the ability of the XRF technology to improve the efficiency of soil removal actions by providing rapid onsite analysis of the soil concentiations of the constituents of potential concern (COPCs). The ultimate goal was to determine if XRF could be used as an onsite guide for the soil removal, thereby focusing the removal on those areas where the COPCs levels exceeded PRGs, which ultimately would speed the removal and minimize costs. The pilot study determined that the XRF technology was only partially successful for providing rapid and accurate onsite analysis.

Before initiating the pilot study, PRGs were calculated for both human health and ecological exposure scenarios (Table 2-1) by evaluating the historical soil data to determine which constituents posed a potential risk to human health and the environment. The PRGs represent soil COPC concentiations that allow for unrestiicted land use and below which no potentially unacceptable risks to human health or the environment are anticipated over that of background. Human health risk PRGs were calculated for each constituent detected in Site 4B soil during the previous field investigations. Silver was the primary ecological COPC at Site 4B and, consequently, the onlyCOPC for which an ecological risk PRG was calculated. A comparison of the human health and ecological PRG for silver was conducted, and the lowest concentiation was selected. Additionally, background concentiations were also considered in the determination of PRGs for the site. Based on this process, iron, manganese, silver, and thallium were the constituents identified with concentiations above the PRGs (CH2M HILL, 2002).

The pilot study was conducted in several phases over approximately 2 years. A preliminary investigation was conducted in July 2002 to calibrate the XRF instiument and further delineate the extent of silver concentiations above the PRG in the westem drainage area.

The general approach of the pilot study, which began in November 2003, involved excavating horizontally and vertically until real-time XRF analysis of residual soil concentrations indicated that soil concentiations for each COPC were less than its respective PRG. A subset of additional soil samples were collected adjacent to XRF samples for offsite laboratory analysis to confirm the results of the XRF analyses. The extent of soil removal was deemed complete when the mean concentiation of each COPC was less than its . respective PRG, as determined by offsite analysis. Additional phases of fieldwork were conducted between February 2004 and May 2005 that consisted of further soil removal and confirmatory sampling. Figure 2-4 shows the extent of the excavation and soil removal and the location of confirmatory sampling. Final backfilling and site restoration activities were completed in September 2005, which concluded the field activities at the site.

Soil removal activities associated with the Site 4B pilot study reduced mean concentrations of manganese, silver and thallium across the site to levels below PRGs. Although concentrations of iron remained above PRGs, site-specific background samples were collected and analyzed for iron and found to be higher than facility-wide background concentrations. Consequently, the Navy, USEPA, and WVDEP concurred that the residual iron concentrations in soil at Site 4B are related to localized background conditions and not due to site releases. The agencies further concurred that no further soil removal for iron was necessary (CH2M HILL, 2006a).

2^


2.2.3 CERCLA Enforcement Activities No CERCLA enforcement actions have been taken at Site 4B.

2.3 Community Participation The Navy, as lead agency for CERCLA activities at ABL, has met the public participation requirements of CERCLA Section 117(a) and the NCP at 40 CFR Section 300.430(f)(3) as follows:

• The notice of availability of the Proposed Remedial Action Plan (PRAP) for Site 4B was published in the Cumberland Times-News and the Mineral Daily News Tribune on Tuesday, March 27, 2007. The public meeting notice is included in this ROD as Appendix A.

• A public comment period was held from April 2, 2007 through May 4, 2007.

• The Site 4B Administiative Record (i.e., the PRAP and supporting documents related to Site 4B) was made available to the public at the following information repositories:

La Vale Public Library 815 National Highway LaVale, MD 21502

Fort Ashby Public Library Lincoln Stieet, IGA Plaza P.O. Box 74 Fort Ashby, WV 26719

• The Navy held a Public Meeting on April 10, 2007 to explain the PRAP and to address public comments. The meeting proceedings were tianscribed by Word for Word Reporting of Swanton, Maryland. The meeting transcript is included as Appendix B to this ROD.

• Written questions and comments were received and answered prior to the Public Meeting. No verbal or written comments were received during the public meeting, and no additional written comments were received during the public comment period. Based upon the comn\ents received, the public did not object to proceeding with the proposed remedy.

In addition to the NCP public participation requirements, the Navy and ABL have had a comprehensive public involvement program for over 10 years. From 1993 to 1996, a Technical Review Committee (TRC) met on average twice a year to discuss topics related to investigative activities at ABL. The TRC was comprised of mostly governmental personnel; however, the meetings were open to the public, and a few private citizens have attended the meetings.

In early 1996, the Navy converted the TRC into a Restoration Advisory Board (RAB), and community representatives joined. The RAB is co-chaired by a comrnunity member and has held meetings, which are open to the public, approximately every 6 months since 1996.

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RECORD OF DECISION, SITE 4B—GROUNDWATER AND SOIL OPERABLE UNIT 14

To assist the Navy in meeting the needs of the local community for information about, and participation in, the ongoing investigation and remedial processes at ABL, the Navy developed a Community Relations Plan (CRP) in 1994 and updated the plan in 2001. The CRP identifies community opinions about the investigation and restoration of potentially contaminated sites at ABL and outlines community relations activities to be conducted during the ongoing and anticipated future restoration activities. Recommendations for future community relations activities are based on information about community opinions and the effectiveness of public participation activities to date, which were obtained during interviews with members of the local community.

2.4 Scope and Role of Operable Unit or Response Action Site 4B is one of the sites identified in the Federal Facilities Agreement (FFA) between the Navy and USEPA for ABL. A list of all ABL sites can be found in the Site Management Plan (SMP) for ABL (CH2M HILL, 2006b). Over the last 9 years, eight RODs (including one interim ROD) have been signed for five sites at ABL in accordance with the priorities established in the SMP.

As of the date of this ROD, remedy decisions and associated remedies have been implemented at five of the 12 top priority sites at ABL. The designation, media, and remedial action identified in the ROD for each of the five sites are listed below:

• Site 1 — Groundwater, Surface Water, and Sediment (OU 03): Site-wide groundwater extiaction and tieatment (ROD May 1997)

• Site 3 - Groundwater and Soil (OU 13): NFA (ROD March 2007)

• Site 5 - Landfill Contents and Surface Soil (OU 01): Capping (ROD January 1997)

• Site 5 — Groundwater, Surface Water, and Sediment (OU 02): Installation of permeable reactive barrier, monitored natural attenuation (MNA), and long-term monitoring (LTM) (ROD February 2006)

• Site 7-Former Beryllium LandfiU (OU 07): Landfill contents removal in 1997 (NFA ROD September 2001)

• Site 10 — Groundwater (OU 05): Groundwater extiaction and tieatment (Interim ROD June 1998; Final ROD August 2005)

• Site 10-Soi l (OU 06): NFA (ROD March 2007)

This ROD addresses Site 4B soil and groundwater. Based on the results of the Site 4B investigations, including the pilot study as well as the associated soil excavation and removal, the Navy, USEPA, and WVDEP have determined that the site does not pose an unacceptable risk to human health or the environment under current and potential future land use and exposure scenarios. Therefore, NFA is required for Site 4B to allow unrestiicted land use.

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SECTION 2-DECISION SUMMARY.

2.5 Site Characteristics

2.5.1 Site Overview Site 4B is situated in the southeastern portion of Plant 1 at ABL, approximately 3,000 ft from the North Branch Potomac River. The most significant physiographic feature in the vicinity of ABL is Knobly Mountain, located to the southeast of Site 4B (Figure i2-l). Detailed descriptions of the ABL geology and hydrogeology (including that for Site 4B) are presented in the RI and Phase II RI (CH2M HILL, 1996a, 1996b). A brief description of the subsurface conditions at Site 4B is presented below.

Two predominant geologic units exist in the subsurface at ABL: shallow, unconsolidated alluvial deposits, and an underlying bedrock unit. The unconsolidated alluvial deposits overlying bedrock consist of two distinct layers of material: an upper, or surficial, silty clay that is likely floodplain deposits, and a deeper sand and gravel layer (alluvium), with variable but typically significant amounts of clay and silt and an average thickness of 14.5 ft. It is this lower portion of the unconsolidated material that is saturated and represents the unconfined alluvial aquifer at the site. Groundwater in the alluvium at Site 4B flows generally north-northeast toward the North Branch Potomac River and has been calculated to flow at a rate of approximately 5 ft per year (CH2M HILL, 1996b).

Shale bedrock, with some interbedded limestone, underlies most of Plant 1. Groundwater flow in the bedrock aquifer is confined to the bedding planes, fractures, and solution channels at Plant 1. The Wills Mountain anticlinorium axis bisects Plant 1 in a north-northeasterly direction. Site 4B probably lies on the southeast limb of the anticline, where bedding planes dip gently to the southeast at approximately 30 degrees. Therefore, the southeastward trending dips of the bedrock bedding planes beneath Site 4B likely channel bedrock groundwater flow in a northeastward direction, as indicated by measured groundwater levels in the vicinity of the site.

2.5.2 Sampling Strategy Information about Site 4B media has been gathered from the soil and groundwater samples that have been collected at the site since the IAS/ CS. (See the chronology of the investigations in Section 2.2.2.). Soil and groundwater samples were collected as part of the CS. Additional groundwater samples were collected as part of the Rl (CH2M HILL, 1996a), and both soil and groundwater samples were collected as part of the Phase II RI (CH2M HILL, 1996b). These samples were collected to determine the nature and extent of contamination and to evaluate the associated risks to human health and the environment. Subsequent to the Phase II RI, additional soil samples were collected at Site 4B to further evaluate the potential impact to soil from the discharge of spent photographic solutions and to provide sufficient additional data to aid in the development of PRGs for the pilot study. Post-excavation confirmatory soil samples were also collected to verify achievement of PRGs. Section 2.5.4 provides a discussion of the sample results.

2.5.3 Source of Contamination The site was identified for investigation due to the potential for discharged spent photographic developing solutions to have released contaminants into the environment.

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2.5.4 Nature and Extent of Chemicals in Site 4B Groundwater and Soil Data collected during various investigations at the site (Section 2.2.2) identified constituent concentiations in groundwater and soil such that the nature and extent of contamination and potential risks could be adequately determined. The nature and extent of constituents in Site 4B groundwater and soil are discussed below by media. The discussion below focuses on the concentiations of COPCs identified during the HHRA and by the additional soU sampling conducted in 2000, as well as the constituents of concem (COCs) identified during the ERA. The concentiations of COPCs and COCs in soil reported here were determined prior to the soil excavation and removal completed as part of the XRF pilot study, and these values were used to calculate the PRGs for the pilot study (CH2M HILL, 2002, 2003).

2.5.5 Surface Soil Surface soil samples collected during the Phase II RI (CH2M HILL, 1996b) and during the additional soil sampling performed in June 2000 (CH2M HILL, 2000) are shown in Figure 2-3. Surface soil in several areas at Site 4B was found to have COPCs exceeding the calculated PRG values.

• Iron was found to exceed the PRG of 27,600 mg/kg for surface soil in two locations (S4-2 and S4-3S/3). One of these samples was collected along the stormwater drainage ditch north of the site, and one was collected at the end of the concrete drainage culvert where it intersects the underground terra cotta-and-steel pipe.

• Two surface soil samples (AS04B-SB03 and AS04B-SB08) contained manganese above the PRG of 680 mg/kg. Sample AS04B-SB03 was collected adjacent to the concrete drainage culvert just outside Building 181, and AS04B-SB08 was collected along the stormwater drainage ditch to the north of the site'.

• Silver was detected in seven surface soil samples above its PRG of 107 mg/kg. These soil samples were collected adjacent to the concrete drainage culvert just outside Building 108 and along the stormwater drainage ditch north of the site.

• Thallium was detected in one surface soil sample (AS04B-SB02 and in its duplicate AS04B-SB14) above the PRG of 2.7 mg/kg. This sample was collected directly adjacent to the southeast corner of Building 181, where spent photographic solutions were discharged from the building.

2.5.6 Subsurface Soil Subsurface soil samples collected during the Phase II RI (CH2M HILL, 1996b) are shown in Figure 2-3. Iron and manganese were the only two inorganics that exceeded the calculated PRGs in the subsurface soil:

• Iron was found to exceed the PRG of 30,600 mg/kg for subsurface soil in two locations (26-2 and S4-3S/3). One of these samples was collected just to the east of the stormwater drainage ditch north of the site; the other sample was collected at the end of the concrete drainage culvert where it intersects the underground terra cotta-and-steel pipe.

• One subsurface soil sample (26-1) contained manganese above the PRG of 680 mg/kg. Sample 26-1 was collected along the stormwater drainage ditch to the north of the site.

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• Silver was not detected in any of the three subsurface soil samples above its PRG of 107 mg/kg.

• Thallium was not detected in any of the three subsurface soil samples above the PRG of 2.7 mg/kg.

During the XRF pilot study conducted between November 2003 and May 2005, the.areas with surface and subsurface concentiations of soil COPCs above the PRGs were excavated and removed (Figure 2-4). Confirmatory soil samples (analyzed via both XRF and offsite laboratory) verified that the soil removal was successful in reducing the mean concentiations of manganese, silver, and thallium below the corresponding PRGs. Residual iron concentrations were determined by site-specific background sampling and found by the Navy, USEPA, and WVDEP to be attiibutable to local background conditions, rather than to historical releases of spent photographic solutions. Consequently, no unacceptable human health or ecological risks remain for exposure to soils at Site 4B over that of background. A detailed discussion of the results of the XRF pilot study and soil removal are presented in the Pilot Study Report (CH2M HILL, 2006a).

2.5.7 Groundwater Groundwater data from monitoring wells 4GW01 (alluvial) and 3GW04 (bedrock) and one alluvial direct-push groundwater sample (S4-GW1) located at the site (Figure 2-3) were used to evaluate the nature and extent of groundwater contamination. The alluvial groundwater data were used for the HHRA because it was determined by USEPA Region 111 that alluvial groundwater represented the reasonable worst-case groundwater supply scenario and the most likely groundwater supply scenario at the site (CH2M HILL, 1996b).

Alluvial well 4GW01 was sampled periodically between 1985 and 1992, and bedrock well 3GW04 was sampled periodically between 1987 and 1994. The alluvial direct-push groundwater sample (S4-GW1) was collected at Site 4B during the Phase II RI in 1994.

The samples collected from the down gradient alluvial well (4GW01) were analyzed for VOCs, SVOCs, metals, and explosives during the Rl and for total cyanide during the Phase II Rl. VOCs (1,1,1-tiichloroethene, carbon disulfide, methylene chloride, toluene and TCE) were sporadically detected throughout the sampling events. TCE was. detected in excess of the federal MCL, at a maximum concentiation of 37 ppb in 1986; however, it was not detected in the most recent sampling event (1992). Further, no SVOCs, explosives, or total cyanide were detected in 4GW01 during the RI sampling events. A number of total metals were detected in the most recent sampling event. With the exception of lead, which was detected at a concentiation of 27 ppb (exceeding the Federal Action Level of 15 ppb), all detected constituents were below federal MCLs. However, based on historical disposal practices at the site, lead is not likely to be site-related. The concentiations of lead in soil at Site 4B were within the range of facility background concentrations. Further, the lead concentiation may have been the result of suspended solids often associated with turbidity caused by pumping the well during sampling.

The bedrock well (3GW04) at Site 4B was analyzed for VOCs during the RI, and subsequently sampled and analyzed for VOCs, dissolved inorganics, and total cyanide in 1994 during the Phase II RI. Although concentiations of toluene (ranging from 1 ppb to 4 ppb) and TCE (1 ppb) had historically been detected, 3GW04 contained only acetone at a

2-9


concentiation of 15 ppb (two orders of magnitude below the USEPA Region III tap-water RBC) during the most recent sampling event (1994). This sample also contained concentiations of dissolved arsenic (36 ppb) in excess of the federal MCL and silver at 4.4 ppb (two orders of magnitude below the USEPA Region 111 tap-water RBC). However, based on historical disposal practices at the site, arsenic is not likely to be site-related. This conclusion is further supported by the average concentiation of arsenic in soil at Site 4B, which is below the average facility background concentiation. Total cyanide was not detected.

The direct-push groundwater sample (S4-GW1) collected in the vicinity of the underground pipe at Building 181 was analyzed for VOCs, SVOCs, total inorganics, and total cyanide during the Phase II RI. Results of the analysis showed concentrations of carbon disulfide and acetone at estimated concentiations of 4 ppb for each. Elevated concentiations of a number of metals (i.e., arsenic, barium, beryllium, cadmium, chromium, iron, lead, manganese, and silver) were also detected. However, groundwater samples collected via direct push often contain additional suspended materials attiibutable to sampling techniques, and therefore, the total metals concentiations in this groundwater sample were most likely elevated with respect to actual groundwater conditions. For this reason, direct-push groundwater samples are normally used for screening purposes for non-naturally occurring constituents. No SVOCs or total cyanide were detected.

2.6 Current and Potential Future Site and Resource Uses

2.6.1 Current Site Uses As noted in Section 2.1, Site 4B is located in the southeast developed portion of Plant 1. As such, the current use of the site and adjacent areas is industiial. The Navy anticipates that this area will remain under Navy ownership and will continue in the same capacity for the foreseeable future.

2.6.2 Potential Future Site Uses Site 4B is anticipated to remain an industiial area in the future; therefore, the currently exposed populations (industiial/facility workers) are also applicable for potential future site uses. However, as a result of the actions documented in this ROD future land use will be unrestiicted.

2.7 Summary of Site Risks This section summarizes the results of the baseline HHRA and ERA for Site 4B. A baseline risk assessment evaluates site data to determine potential risks to human health and/or the environment. The potential risks were evaluated for constituents in soil and groundwater for each potential route of exposure.

No unacceptable risks to human health or to the environment over background were identified during the risk assessments prepared for Site 4B, as described below.

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2.7.1 Summary of Human Health Risk Assessment An HHRA was conducted as part of the Phase II RI (CH2M HILL, 1996b) to assess potential human health risks from exposure to the COPCs detected in soil and groundwater at Site 4B. The Phase II RI Report, of which the HHRA is a part, is available at the information repositories listed in Section 2.3. Site 4B soil and groundwater were evaluated using current and future land use scenarios and conservative estimates of current and future human exposure to site contaminants.

As part of the HHRA, a list of COPCs that may have posed risks to potential human receptors was developed and is presented in Table 2-2. The COPC identification process included screening soil and groundwater data against constituent concentrations that could pose a risk to human health.

Six COPCs (benzo[a]pyrene, aluminum, antimony, arsenic, manganese, and silver) were identified for surface soil in the HHRA and one COPC (arsenic) was also identified for the subsurface soil. Six COPCs (aluminum, chromium, lead, manganese, nickel, and vanadium) were identified for the groundwater.

A conceptual exposure model showing exposure routes and potential receptors evaluated in the HHRA is presented in Figure 2-5. An exposure pathway is complete (i.e., there is potential exposure) if there is the potential for the chemical to be ingested, inhaled or absorbed through the skin. Exposure cannot occur unless the exposure pathway is complete. If there is no exposure, there is no risk.

The human health risk calculations performed using the above COPCs identified silver as the primary risk driver through ingestion of surface soil by a potential future child resident. The cumulative hazard index (HI) for ingestion of surface soil by a child was 3 (Table 2-3), which is above the USEPA threshold value of 1. The main constituent that contributed to this hazard was silver (HI = 1.1). A target organ evaluation was conducted for the child ingestion exposure scenario, which demonstrated that a potential hazard to skin above the USEPA threshold level existed.

As discussed in Section 2.5.2, additional soil sampling was performed after the Phase II RI. Although an HHRA was not performed using these data, the data were compared to adjusted USEPA Region III industrial and residential soil RBCs and used to select the COPCs for development of risk-based human health PRGs. RBCs are chemical concentiations that correspond to a threshold risk level such as a hazard quotient (HQ) equal to 0.1 for noncarcinogenic risk or lifetime cancer risk of 10- . Although 17 constituents were detected in soil, as shown on Table 2-4, only six metals (aluminum, arsenic, iron, manganese, silver, and thallium) were detected in the surface soil samples above the adjusted residential soil RBC and were, thus, designated as COPCs. Only arsenic was detected at concentrations above the adjusted industrial soil RBC. Human health risk-based PRGs were calculated for these six COPCs. Comparison of the June 2000 surface soil data to the PRGs (including human health risk-based PRGs) and background concentiations identified four constituents (iron, manganese, silver, and thallium) with concentrations above the PRGs. (CH2M HILL, 2002)

Currently, ABL obtains potable water from supply wells that are located over 1 mile upgradient from Site 4B. As such, groundwater is not used at Site 4B and is not expected to be used as a future potable supply. Therefore, the pathways associated with current and

2-11


future groundwater use at the facility are incomplete. However, potable use of the groundwater was evaluated as a conservative scenario iri the Phase 11 RI, which analyzed exposure to the alluvial groundwater by hypothetical futture adult and child residents (CH2M HILL, 1996b). The HHRA calculated a noncarcinogenic HI of 2.0 for a hypothetical future adult resident and a noncarcinogenic HI of 5.0 for a hypothetical future child resident (Table 2-3). These potential hazards are associated with the ingestion of manganese in groundwater; manganese is the only COPC with a hazard index above 1.0.

Although potential risk above the EPA threshold value was identified for potable groundwater use due to manganese concentiations, manganese is an essential human nutiient and is generally a natural component of groundwater. Further, the intake rates associated with the detected concentiations of manganese in groundwater fall within the tolerable Upper Intake Levels published by the Food and Nutiition Board, Institute of Medicine (Food and Nutiition Board, 2000). In addition, historical concentiations of inorganic chemicals in groundwater at Site 4B were compared to those detected in facility wells not affected by historic releases (i.e., GGW07 and GGW08). Comparisons of corresponding manganese data indicate that the manganese concentiations in Site 4B groundwater are comparable to naturally occurring manganese concentiations elsewhere at ABL and are not attiibutable to releases at the site.

Human Health Risk Assessment Conclusions

Following the soil removal as part of the XRF Pilot Study (CH2M HILL, 2006a), the mean concentiations pf manganese, silver, and thallium in soil remaining at the site are below their respective PRGs (Table 2-5). In addition, the post-removal iron concentiations are not attiibutable to historical releases associated with the spent photographic solutions and are likely representative of localized background concentiations. This conclusion was confirmed by analysis of site-specific background soil samples for iron. Therefore, potential risks to human health from exposure to Site 4B soil are within acceptable levels for purposes of CERCLA.

Although potential risks were identified for a hypothetical potable groundwater use, these risks were associated with concentrations of naturally occurring manganese in groundwater, which is not attiibutable to a release at Site 4B. Additionally, the residual (i.e., post-excavation) concentiations of manganese (ranging between 319 mg/kg and 1,160 mg/kg, with a mean concentiation of 619 mg/kg) in Site 4B soil are below the USEPA Region III soil screening level (SSL) of 6,700 mg/kg which indicates that the residual manganese concentiations in soil are below the level expected to pose a risk to groundwater from leaching. . ,

Based on the results of the HHRA, and the subsequent excavation and removal of soil as part of the XRF Pilot Study (CH2M HILL, 2006a), NFA is needed for Site 4B for soil and groundwater to be protective of human health under industiial or residential use scenarios.

2.7.2 Summary of Ecological Risk Assessment An ERA was conducted during the Phase II RI to assess the potential ecological risks from exposure to ecological COPCs detected at Site 4B (CH2M HILL, 1996b). The ERA evaluated potential ecological risks for both upper trophic-level receptors (via food web exposure) and lower tiophic-level receptors (via direct exposure to surface soil). Surface soil is the only site

2-12


medium available for ecological exposure. Groundwater is not used by ecological receptors at the site, and the subsurface soil (i.e., below about 2 ft) is not a biologically active zone, other than for plants with deep roots, which are not present at Site 4B.

The ERA concluded that silver concentiations in the surface soil posed a potential risk to plants and animals. However, the ERA also found that Site 4B and the adjacent drainage ditch contained limited habitat for ecological receptors (both in terms of size and quality), thereby reducing the potential for exposure. Site 4B and surrounding land uses are industiial. Because the ditch does not contain standing water perennially, it is unlikely to support higher order aquatic receptors. Further, the nature of the ditch (only approximately 2 ft wide) limits site-related silver exposure to within a small area. Plant communities present in the ditch, consisting of dense monotypic stands of cattail, may have been exposed to silver in soil but showed no signs of chemically induced stiess. Further, the saturated nature of the soil in the ditch limits its use by many soil invertebrates (such as earthworms).

Contaminated soil tiom Site 4B and the associated drainage ditch were excavated and removed as part of the XRF Pilot Study (CH2M HILL, 2006a), thereby reducing the mean residual silver concentiation. After excavation, the area was backfilled with 2 ft of clean topsoil.

The primary ecological COPC and risk-driver was silver. The post-excavation mean concentiation of silver in the residual soil is below the PRG; therefore, potential ecological risks from exposure to Site 4B soil are acceptable. Based on the results of the ERA and the subsequent excavation and removal of soil as part of the XRF Pilot Study (CH2M HILL, 2006a), NFA is required for Site 4B to be protective of ecological health.

2.7.3 Selected Remedy NFA is required for soil or groundwater for unlimited land use and unrestricted exposure at Site 4B. This decision is based on the results of the human health and ecological risk assessments, conducted after the XRF Pilot Study and the associated excavation and removal of contaminated soil. The assessments concluded that there are no unacceptable current or future risks associated with soil and groundwater at Site 4B.

2.8 Documentation of Significant Changes The PRAP for ABL Site 4B Soil and Groundwater was released for public conrmient on March 27, 2007. The PRAP recommended no further action as the Preferred Alternative for the site. Written comments were received during the public comment period and were addressed by the Navy. No verbal comments were received during the public meeting on April 10, 2007, or otherwise during the public comment period. The Navy, USEPA, and WVDEP reviewed all written comments and determined that no significant changes to the proposed alternative, as originally identified in the PRAP, were necessary or appropriate.

2-13

Table 2-1 Preliminary Remediation Goals (PRGs)

Site 4B ROD Allegany Ballistics Laboratory Rocket Center, West Virginia

Parameter

Iron (surface)

Iron (subsurface)

Manganese (surface and subsurface)

Silver (surface and subsurface)

Thallium (surface and subsurface)

PRGs (mg/kg)

27,900*

30,900*

680

107

2.7

* PRG is equal to the background soil concentration (CI-I2M HILL, 2003)

Page 1 of 1

Table 2-2 Summary of COPCs for the HHRA


Surface Soil

Ingestion, Dermal, and Inhalation of Airborne Particulates Benzo(a)pyrene Aluminum Antimony Arsenic Manganese Silver

Subsurface Soil

Ingestion, Dermal, and Inhalation of Airborne Particulates Arsenic

Groundwater

Alluvial Aquifer - Tap Water Aluminum Chromium Lead Manganese Nickel Vanadium

Table 2-3 Risk Summary By Media and Receptor -1996 Phase II Remedial Investigation

Site 4B ROD Allegany Ballistics Laboratory, Rocket Center, West Virginia

Current

Worker Adult Cancer Noncancer

Future | Resident

Child and

Adult ' • ' Cancer

Child Noncancer

Adult Noncancer

Construction Worker Cancer Noncancer|

Surface Soil | Inhalation Ingestion Deirmal Total

2.3E-06 4.7E-06 7E-06

1.4E-02 2.9E-02 4E-02

2.2E-05 2.5E-05 5E-05

2.2E+00 6.9E-01 3E+00

2.4E-01 1.7E-01 4E-01

1.8E-08 8.8E-07 1.9E-07 1E-06

1.4E-03 6.6E-01 6.4E-02 7E-01

Subsurface Soil Inhalation Ingestion Dermal Total

1.6E-08 7.7E-07

. 1.7E-07 1E-06

2.5E-04 1.2E-01 2.6E-02 1E-01

Groundwater^ Inhalation Ingestion Dermal Total

5.4E-05 4.6E-08 5E-05

4.5E+00 1.OE-02 5E+00

1.9E+00

2E+00

All total numbers are rounded to the nearest whole number. ^ The soil cancer risk for a combined child and adult (age-adjusted). ' The groundwater cancer risk for inhalation is for an adult, the ingestion is a combined child and adult (age-adjusted), and the

dermal is for the child. ' Reasonable maximum exposure scenario. Most likely exposure scenario was not evaluated because there are currently no Site 4B bedrock wells.

Table 2-4 Summary of COPCs - Field Investigation Sampling (May - June 2000)


Soil Aluminum

Arsenic Iron

Manganese Silver

Thallium

Table 2-5 Mean Soil Concentrations - Site 4B Pilot Study


Chemical Name Mean PRG

Total Metals (MG/KG)

Iron (Surface Soil)

Iron (Subsurface Soil)

Manganese

Silver

Thallium

34,089

37,285

613

50.7

0.93

27,600

30,600

680

107 2.7

Note: For results that were not detected, one half of the detection limit was used when calculating the mean value for that compound. This is consistent with human health risk assessment guidelines (EPA 2002).

RIe Path: V:V18gls^bl\figures\site2prap.apr

Source: USGS 7.5 minute Cresaptown, WV-MD digital quadrangle map

Hh One Inch Equals Two Thousand Feet

Figure 2-1 Facility and Site Location Map Site 4B ROD Allegany Ballistics Laboratory Rocket Center, West Virginia

CH2IVIHILL

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Former Underground Pipe

Former Concrete Drainage Culvert

Former Discliarge Pipe

LEGEND I—I Building ^ / Drainage Ditch Exi Electrical Boxes . ' v ' Underground Pipe O Fonner Transfonners A ^ Discharge Pipe A / Edge of Pavement A ^ Fence

/ v * Bunkers

A 25 25 50 Feet

Figure 2-2 Former Site Layout


CH2MHILL

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LEGEND A / Edge of Pavement # Direct Push Dirt Road 0 Multi-Media /...• Bunkers (H Aluvial Monitoring Well / s / Drainage Ditch

A Surface Soil Sample Locations / y pence Building Q Transformers

Bedrock Monitoring Well

A 35 70 Feet

Figure 2-3 Historical Sampling Locations


CH2MHILL

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• • .

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345

LEGEND ® Soil Sample Locations

I ! Building I I Electrical Boxes ^ H Transformers

A ( J ^ Discharge Pipe A / Fence

A / Edge of Pavement •• •,' Bunkers Dirt Road r ^ Area of Excavation

30 60 Feet

Figure 2-4 Confirmatory Sample Locations and Areas of Excavation


CH2MHILL

Medium Release Mechanism/Pathway

ES052007010WDC 3

Exposure Routes & Potential Receptors

Current Scenario Future Scenario

Soils

Surface y Volatiles or airborne particulates —»-

Direct contact »•

Racreational Rocraational Child Adutt Construction Worker Mjuth Adult Residsnt Resident Worker

Inhalation

tngsstion

Demiai

• •

• •

• •

• • •

Subsurface Inhalation

Ingestbn

Dermal

• • •

Groundwater -

Alluvial

Bedrock

Inhalation

Ingestion

Dennal

X

X

X

• •

* •

• Denotes exposure pathways and routes selected for quantitative risk assessment.

X Denotes exposure pathways selected for qualitative risk assessnrwnt.

Figure 2-5 Exposure Model

Site 4B ROD Allegany Ballistics Laboratory Superfund Site

Rocket Center, West Virginia

CH2MHILL

SECTION 3

Responsiveness Summary

The selected alternative for Site 4B is NFA. Written comments, received and addressed by the Navy during the public comment period, are documented below. No verbal comments, concems, or questions were received by the Navy, USEPA, or the WVDEP during the public comment period, which was held from April 2, 2007 through May 4, 2007.

A public meeting was held on April 10, 2007 to present the PRAP for Site 4B and address any questions or comments on the PRAP and on the supporting documents in the information repositories. No written or verbal comments, concerns or questions were received during the public meeting.

The limited number of comments and the content of those comments suggest that the public does not disapprove of the selected altemative. The transcript of the public meeting is part of the Administrative Record for this site and a copy is included as Appendix A of this ROD.

3.1 Stakeholder Issues and Lead Agency Responses Written comments and responses received during the public comment period are presented below.

1. What is the proposed plan for Site 4B soil and groundwater?

Navy Response: The proposed plan or PRAP for Site 4B soil and groundwater at ABL is the document used to facilitate public involvement in the remedy selection process. The PRAP summarizes key information, identifies and explains the reasons behind the Navy's preferred altemative, and solicits public comment on the preferred alternative.

The Navy in conjunction with USEPA, and in consultation with WVDEP, is required to issue the PRAP pursuant to the public participation requirements established under Section 117(a) of CERCLA, as amended, and Sections 300.430(f)(2) and (3) of the NCP.

2. You said something about... it was a chemical left from X-ray, what chemical?

Navy Response: Site 4B is referred to as the Spent Photographic Developing Solution Site. During the 1950s and early 1960s, spent photographic and X-ray developing solutions (containing silver, cyanide, and phenols) were discharged through a hose, into a concrete drainage channel, and then underground into a pipeline constructed of terra cotta and steel.

Environmental sampling conducted in the mid-1980s and 1990s revealed the presence of silver in the soil as the primary contaminant at the site and, to a lesser extent, manganese and thallium. Subsequent investigations were conducted to define the extent of the contamination, which ultimately culminated in the removal of contaminated soil.

3-1


3. How much ground is involved?

Navy Response: The removal of soil at Site 4B was conducted in four phases and resulted in the excavation and offsite disposal of over 220 cubic yards (yd^) of contaminated soil. The initial phase conducted in November 2003 removed approximately 200 yd^ of contaminated soil from the site. The second phase conducted in February 2004 removed approximately 20 y(P of contaminated soil. Additional minor amounts of contaminated soil were removed in March 2004 and July 2004, as part of the third and fourth phases.

4. Will it affect, or has it affected, the groundwater?

Navy Response: Prior to the removal of contaminated soil, the Navy conducted an investigation of groundwater at Site 4B to determine if the concentrations of contaminants within the soil may have adversely impacted groundwater. Groundwater samples were collected and analyzed, and a HHRA was performed to determine if there were potential risks from exposure to the groundwater.

Although groundwater at Site 4B is not used as a potable water supply, the Navy evaluated the future potable use of groundwater by adult and child residents as a conservative or worst-case scenario. Under the most conservative criteria, a potential risk was identified for a potable use scenario, due to concentrations of naturally occurring manganese, that were determined to be unrelated to the site.

Furthermore, following the completion of the XRF Pilot Study and soil removal activities, additional confirmatory soil sampling was performed. The results of this indicated that residual mean concentrations of manganese in soil are below the USEPA Region 111 soil screening levels, and therefore are not expected to pose a risk to groundwater from leaching.

5. You said it was an on-going job. How long has it been going on and when will it be finalized?

Navy Response: The Navy has several sites at ABL where investigations of potentially contaminated soil and groundwater are currently being conducted, or have been conducted. Site 4B was originally identified during the IAS in 1983 and has been part of a number of investigations conducted from the mid-1980s through to the present. Following the removal of contaminated soil, field activities were concluded with the final backfilling and site restoration, completed in September 2005. Subsequent reporting and documentation has continued through to the present, which culminates with the signature of this Record of Decision as the final action for Site 4B.

6. WTiat is the preferred remedy?

Navy Response: The preferred alternative is that no further action is necessary for soil or groundwater for unrestricted land use at Site 4B. The reason NFA is necessary is based upon the results of the human health and ecological risk assessments, and because the removal of contaminated soil, associated with the XRF pilot study, reduced concentrations of contaminants in soil to levels protective of human health and the environment.

7. Could you tell me briefly what the Final Pilot Study Report 2006 concluded?

Navy Response: One of the primary objectives of the XRF Pilot Study (CH2M HILL, 2006a) was to evaluate the ability of a field portable X-Ray Fluorescence Analyzer to provide real-

3-2

SECTION 3-RESPONSIVENESS SUMMARY

time concentrations of iron, manganese, silver and thallium in soil so that the amount and cost of soil removal could be minimized.

Based upon confirmatory analytical results, the technology was not useful in guiding soil removal based on real-time analytical results for manganese, silver and thallium, particularly in the presence of high iron concentrations. The technology performed adequately for detecting iron at concentrations that correlated with offsite laboratory values, and was able to identify the presence or absence of silver, but not at an accurate concentration.

Although the pilot study produced mixed results in regard to its primary objective, the associated soil removal was successful in reducing the mean concentrations of iron, manganese, silver, and thallium to acceptable levels with respect to human health and ecological risks and background.

3-3

SECTION 4

References

CH2M HILL. 1996a. Remedial Investigation of the Allegany Ballistics Laboratory. January.

CH2M HILL. 1996b. Phase II Remedial Investigation at Allegany Ballistics Laboratory Superfund Site, Mineral County, West Virginia. August.

i

CH2M HILL. 2000. Draft Technical Memorandum, Soil and Groundwater Sampling and Well Installation Activities at Site 4B and Site 10 at Allegany Ballistics Laboratory. January.

CH2M HILL. 2001. Preliminary Remediation Goals for Site 4B at Allegany Ballistics Laboratory Technical Memorandum. June.

CH2M HILL. 2002. Preliminary Remediation Goals for Site 4B at Allegany Ballistics Laboratory Technical Memorandum. September.

CH2M HILL. 2003. Addendum to Final Technical Memorandum - Preliminary Remediation Goals for Site 4B Soil ai Allegany Ballistics Laboratory. October..

CH2M HILL. 2006a. Final Site 4B Pilot Study Report. March.

CH2M HILL. 2006b. 2006 Site Management Plan, Allegany Ballistics Laboratory, Rocket Center, West Virginia. August.

Environmental Science and Engineering(ES&E). 1983. Initial Assessment Study of Allegany Ballistics Laboratory. January.

Food and Nutrition Board, Institute of Medicine. 2000. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, D.C. National Academy Press,

Roy F. Weston, Inc. (Weston). 1989. Interim Remedial Investigation for Allegany Ballistics Laboratory. October.

United States Environmental Protection Agency (USEPA). 1988. Guidance for Conducting Remedial Investigation and Feasibility Studies under CERCLA. OSWER Directive 9355.3-01. EPA/540/9-89/004. October.

4-1

Appendix A Public Meeting Notice

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Appendix B Public Meeting Transcript

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