I ^'200s lih · CONTENTS 2.12.2 Descriptiori of Selected Remedy 2-24 2.12.3 Summary of Estimated Remedy Costs 2-26 2.12.4 Expected Outcomes of Selected Remedy 2-26

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SDMS DocID 2109669

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iun I / ^ O G

^'200s l i h

RECORD OF DECISION

SITE 10: FORMER TCE STILL AND PLANT PRODUCTION WELLS "M' AND " C

GROUNDWATER (OPERABLE UNIT 5)

at the

ALLEGANY BALLISTICS LABORATORY ROCKET CENTER, WEST VIRGINIA

August 2005

Contents

Declaration 1-1

1.1 Site Name and Location 1-1 1.2 Statement of Basis and Purpose 1-1 1.3 , Assessment of the Site ..1-1 1.4 Description of Selected Remedy 1-1 1.5 Statutory Determinations 1-2 1.6 ROD Data Certification Checklist! '. 1-2 1.7 Authorizing Signatures 1-4

Decision Summary .' 2-1

2.1 Site Name, Location, and Description 2-1 2.2 Site History and Enforcement Activities 2-1

2.2.1 History of Site Activities 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 2-7 2.5 Site Characteristics ;..... 2-8

2.5.1 Site Overview :..... ;....2-8 2:5.2 Sampling Strategy ;..... 2-9 2.5.3 Source of Containination 2-9 2.5.4 Nature and Extent of Chemicals in Site 10 Groundwater 2-9

2.6 Current and Potential Future Site and Resource Uses ..2-10 2.6.1 Current and Potential Future Site Uses : ...2-10 2.6.2 Current and Potential Future Groundwater and Surface Water Uses ...2-10

2.7 Summary of Site Risks..... ....: 2-11 2.7.1 Summary of Human Health Risk Assessment ..;...2-11 2.7.2 Summary of Ecological Risk Assessment 2-14 2.7.3 Basis for Action ,...2-14

2.8 Remedial Action Objectives (RAOs) :..2-14 2.9 Description of Alternatives .....;.... 2-15

2.9.1 Description of Remedial Alternatives .:. 2-16 2.9.2 Common Elements and Distinguishing Features of Each Alternative...2-19 2.9.3 Expected Outcomes of Each Alternative ....2-20.

2.10 Summary of Comparative Analysis of Alternatives...-. 2-20 2.10.1 Threshold Criteria .........2-21 2.10.2 Primary Balancing Criteria '.... 2-22 2.10.3 Modifying Criteria 2-23 2.10.4 Remedial Alternatives Comparative Analysis Summary 2-24

2.11 Principal Threat Waste 2-24 2.12 Selected Remedy 2-24

2.12.1 Summary of the Rationale for the Selected Remedy , 2-24

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CONTENTS

2.12.2 Descriptiori of Selected Remedy 2-24 2.12.3 Summary of Estimated Remedy Costs 2-26 2.12.4 Expected Outcomes of Selected Remedy 2-26

2.13 Statutory Determination 2-26 2.13.1 Protection of Human Health and the Environment.. 2-27 2.13.2 Compliance with ARARs 2-27 2.13.3 Cost Effectiveness 2-27 2.13.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent Practicable 2-27 2.13.5 Preference for Treatment as a Principal Element 2-28 2.13.6 Five-Year Review Requirements 2-28

2.14 Documentation of Significant Changes 2-28

3 Responsiveness Summary..... 3-1

3.1 Stakeholder Issues and Lead Agency Responses 3-1

Tables (located at the end of Section 2)

2-1 Summary of Chemicals of Potential Concem for Site 10 Groundwater - Future Residential Scenario

2-2 Selection of Exposure Pathways for Site 10 Groundwater 2-3 Exposure Factors for Site 10 Groundwater 2-4 Risk Summary by Receptor for Site 10 Groundwater 2-5 Toxicity Information for Chemicals of Potential Concern 2-6 Comparative Analysis of Alternatives 2-7 Summary of Costs for the Selected Remedy 2-8 Description of ARARs for the Selected Remedy

Figures (located at the end of Section 2)

2-1 Facility Location 2-2 Site 10 Associated Features 2-3 Site 10 Conceptual Site Model for Contaminated Groundwater 2-4 VOCs in Site 10 Alluvial Groundwater 2-5 VOCs in Site 10 Bedrock Groundwater 2-6 Locations of Existing and Proposed Extraction Wells at Site 10

2-7 Area of Restricted Groundwater Use at Site 10

Appendices

Appendix A Public Meeting Transcript

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1 Declaration

1.1 Site Name and Location Site 10: Former TCE StiU and Plant Production Wells A and C

Groundwater (also identified as Operable Unit [OU] 5) Allegany Ballistics Laboratory (ABL), Rocket Center, West Virginia National Superfimd Database Identification Number: WV0170023691

1.2 Statement of Basis and Purpose This decision document presents the final selected ren\edy for Site 10 Groundwater at ABL in Rocket Center, West Virginia (the "site"). The final selected remedy was chosen in accordance with the Comlprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986, and, to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is based oh the Admirustrative Record file for this site.

1.3 Assessment of the Site The response action selected in this Record of Decision (ROD) is necessary to protect public health or welfare or the environment from actual or threatened releases of hazardous substances, pollutants, or contaminants in groundwater at Site 10.

1.4 Description of Selected Remedy The U. S. Navy (the Navy) wUl manage contamination at Site.10 in two separate actions, based on media, or OUs. The remedial action selected in this ROD addresses contamination associated with groundwater and is to be implemented as OU 5. OU 6, defined as contaminated subsurface soil and identified as the contaminant source material at Site 10, will undergo separate remedial alternative evaluation and selection.

Ciirrently, contaminated groundwater at Site 10 (OU 5) is being addressed under an Interim ROD, in which containment of the most highly contaminated portion of the groundwater (referred to as the "hot spot") is the primary objective. Since the interim remedial action was initially implemented in February 1999, additional data have been gathered concerning the performance of the existing remedial action and the alternatives available to address the remaining groundwater contamination at the site. In 2003, the interim remedial action was expanded to accommodate extraction and tieatment of more of the groundwater. The Navy, as lead agency, in conjunction with the U. S. Environmental Protection Agency Region III (EPA), has selected continuation of site-wide groundwater extraction and discharge to the Site. 1 groundwater treatment plant, initiated under the Interim ROD, coupled with a long-

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1-DECLARATION

term groundwater monitoring plan and land use controls as the final remedial action in order to adequately address the potential risks associated with exposure to contaminated groundwater at Site 10.

The major components of the selected remedy are:

• A groundwater use restriction imposed through appropriate physical and administrative mechanisms until the remedial action objectives (RAOs) are achieved. The Navy will be responsible for implementing, maintaining, monitoring, and enforcing this groundwater use restriction to limit access to and use of contaminated groundwater atSitelO.

• Continued groundwater extraction from four alluvial extraction wells and four bedrock extraction weUs, initiated under the authority of the Interim ROD.

• Previously completed modifications of the pipeline installed for the interim remedial action to transport groundwater from Site 10 extraction wells to the Site 1 tieatment plant.

• Continued discharge of the treated groundwater to the North Branch Potomac River or, on an as-needed basis, the facility's steam generation plant, also initiated under the hiterim ROD.

• Groundwater monitoring in accordance with the long-term monitoring plan to evaluate groundwater quality, contaminant migration, and remedial system performance for inclusion in the 5-year reviews. The long-term monitoring plan has been developed by the Navy and awaits review and approval by the E P A and WVDEP, in accordance with this ROD.

The State of West Virginia concurs with the selected remedy.

1.5 Statutory Determinations The Selected Remedy for Site 10 groimdwater is protective of human health and the envirorunent, complies with Federal and State requirements that are legally applicable or relevant and appropriate to the remedial action, is cost effective, and utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable.

This remedy also satisfies the statutory preference for tieatment as a principal element of the remedy.

Because this remedy will result in hazardous substances, pollutants, or contaminants remaining on-site above levels that allow for unlimited use and urirestiicted exposure, a statutory review will be conducted within five years after initiation of this remedial action to ensure that the remedy is, or will be, protective of human health and the environment.

1.6 ROD Data Certification Checklist The following information is included in the Decision Summary section of this ROD. Additional information can be found in the Administrative Record file for ABL Site 10.

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1 - DECLARATION

Chemicals of Potential Concem (COPCs) and their respective concentrations (Section 2.5.4)

Baseline risk represented by the COPCs (Section 2.7)

Cleanup levels established for the COPCs and the basis for these levels (Section 2.8)

An explanation of how source materials constituting principal threats are addressed (Section 2.11)

Current and reasonably anticipated future land use assumptions and current and potential future beneficial uses of groundwater used in the baseline risk assessment and ROD (sections 2.6 and 2.7)

Potential land and groundwater use that wiU be available at Site 10 as a result of the successful execution of the selected remedy (Section 2.12.4)

Estimated capital, aimual operation and maintenance (O&M), and total present worth costs, discount rate, and the number of years over which the remedy cost estimates are projected (Section 2.9)

Key factor(s) that led to selecting the remedy (i.e., description of how the selected remedy provides the best balance of fradeoffs with respect to the balancing and modifying criteria, highlighting criteria key to the decision) (sections 2.10 and 2.12)

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1-DECLARATION

1.7 Authorizing Signatures

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

OS"

Abraham Ferdas, Director Date Hazardous Site Cleanup Division U.S. EPA Region III

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

Ken Ellison, Director Date Division of Land Restoration West Virginia Department of Environmental Protection

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2 Decision Summary

2.1 Site Name, Location, and Description Site 10: Former TCE Still and Plant Production Wells A and C

Groundwater (also identified as OU 5) Allegany Ballistics Laboratory, RocketCenter, West Virginia National Superfund Database Identification Number: WVOl 70023691 Lead Agency: Department of the Navy . Support Agencies: US Environmental Protection Agency Region III (Lead Regulator)

West Virginia Department of Environmental Protection

Source of investigation and removal action funds: Environmental Restoration, Navy (ER,N)

Allegany Ballistics Laboratory (ABL) is a research, development, and production facility located in Rocket Center, West Virginia, in the northern 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 A T K Tactical Systems Company LLC (ATK), occupies approximately 1,577 acres, of which only 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-acfe facility adjacent to Plant 1, is owned and operated by ATK. In May 1994, Plant 1 was listed on the National Priorities List (NPL). Plant 2 is not on the NPL- Figure 2-1 shows the location of ABL (including Plant 1 and Plant 2) and the approximate locations of its CERCLA sites.

As shown in Figure 2-1, Site 10 is located in the south-cential area of the developed portion of Plant 1. The site comprises the area that includes the former tiichloroethene (TCE) still at Building 157, former Production Well A (PWA), and former Production Well C (PWC) (Figure 2-2), where contamination has been found and attributed to the historic activities at Building 157 involving distillation of used degreasing solvents. The site was originally designated Site PWA, but, in order to be consistent with other numbered sites at ABL, it was renamed Site 10 in 1995.

2.2 Site History and Enforcement Activities

2.2.1 History of Site Activities Building 157 was constiucted in the 1950s as a chamber preparation building for the A2 Polaris second stage rocket motor casing. TCE use at the building involved a solvent recovery still just outside the southeast side of the building, where TCE was recovered by distilling. TCE use and storage at Building 157 began about 1960, but ceased in the early 1960s (facility-wide use of TCE at ABL was discontinued in the early 1990s). For purposes of this Record of Decision (ROD), it has been determined that the TCE from the distilling activities is the likely source of the contamination detected in groundwater at Site 10,

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2-DECISION SUMMARY

2.2.2 Previous Investigations Site 10 was the subject of a number of investigations and other activities between 1984 and ' 2001. Below is a brief chronological description of each of these activities. More detailed descriptions can be found in the investigation-specific documents referenced.

Confirmation Study (CS) /Interim Remedial Investigation (Interim RI) Between 1984 and 1987, the Confirmation Study (CS) was conducted under the Navy Assessment and Contiol of Installation Pollutants Program (NACIP) at several Plant 1 sites. It was during this investigation that contamination was first discovered in several of the Plant 1 production wells. PWA, which is located approximately 400 feet south of the former TCE still at Building 157, and PWC, which is located about 600 feet northeast of the former TCE still, were evaluated and found to contain detectable concentiations of several volatile organic compounds (VOCs), including TCE.

As a result of the Superfund Amendments and Reauthorization Act of October 1986, the Navy changed its NACIP terminology and scope under the Installation Restoration Program (IRP) to follow the rules, regulations, guidelines, and criteria established by EPA for the Superfund program. Therefore, the results of the CS are documented in the Interim Remedial Investigation for Allegany Ballistics Laboratory (Roy F. Weston, Inc., October 1989).

Remedial Investigation (RI) A focused facility audit was conducted during the RI to determine the potential source(s) of VOC contamination detected in PWA and PWC during the CS. It was during this audit that the historical TCE distilling operation at Building 157 was identified and its potential connection to the contamination found in PWA and PWC recognized. Therefore, soil sampling was conducted during the RI that focused on the area around the former TCE still. Additional investigation of groundwater in PWA and its associated monitoring wells (bedrock monitoring well PWA-1 and alluvial monitoring well PWA-2) also was conducted.

The results of soU sampling confirmed the presence of TCE in the soil around the former TCE still, and the groundwater data also verified the presence of VOC contamination in both the alluvial and bedrock aquifers around PWA. The results of the RI, documented in the Remedial Investigation ofthe Allegany Ballistics Laboratory Report (CH2M HILL, January 1996), indicated that there was a need for additional investigation to better define the nature and extent of contamination and to evaluate the potential risks posed by the contamination to human health and the environment.

Phase II Remedial Investigation (Phase II RI) Based on tiie recommendations of the RI Report, the Phase II RI at Site 10 (then still referred to as Site PWA) was performed in 1994 to collect the additional information determined in the RI to be necessary. Additional soil samples were collected for a wider range of chemicals than had bfeen evaluated during the RI, and additional groundwater samples were collected to evaluate the extent of groundwater contamination in the vicinity of the former TCE still.

The results of the Phase II RI confirmed that VOCs were the primary chemicals of potential concern (COPCs) at Site 10 and that the former TCE still was the likely source of the contamination detected at the site.

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2-DECISION SUMMARY

The 1994 Phase II RI also included a baseline human health risk assessment (HHRA) and ecological risk assessment (ERA) that evaluated the potential risks to human health and the environment posed by site contaminants, based on the current EPA guidance and current and potential future land uses at the site. The results of the HHRA and ERA, documented in the Phase II Remedial Investigation at Allegany Ballistics Laboratory Report (CH2M HILL, August 1996), indicated that the primary risk at Site 10 was posed by the potential future use of contaminated groundwater by people, due to the levels of VOCs found in the groundwater.

Phase I Aquifer Testing The investigations leading up to and including the Phase II RI determined that groundwater contamination existed at Site 10, identified the probable source of the contamination, and determined that the contaminated groundwater posed a potential risk to future groundwater users. Therefore, it was necessary to evaluate potential remedial alternatives for addressing the contamination in a feasibility study (FS). However, before the alternatives could be evaluated, the full extent of contamination (in both the alluvial and bedrock aquifers) and the aquifer characteristics that would influence the effectiveness of any remedial alternative had to be determined.

To provide the necessary information for evaluating remedial alternatives. Phase I Aquifer Testing was conducted in late 1995 and early 1996. During the study, a number of both alluvial and bedrock wells were installed and tested to determine not only the extent of the groundwater contamination, but also the characteristics that govern groundwater movement in both the alluvial and bedrock aquifers. As part of this effort, a groundwater flow model was developed to simulate how groundwater extraction might be used to capture groundwater contamination at Site 10. The results of these activities are documented in the Phase I Aquifer Testing at Allegany Ballistics Laboratory Superfund Site Report (CH2M HILL, December 1998). ; ,

Phase II Aquifer Testing Phase II Aquifer Testing was performed at Site 10 in late 1996 to evaluate the assumptions used in the groundwater flow model developed during Phase I Aquifer Testing and to gather information for the design of a possible groundwater extraction systeni. Observations made during Phase II Aquifer Testing indicated that the aquifer characteristics were not uniform, but changed in an eastward direction across Site 10. Based on this testing, groundwater exfraction was thought not to be a technically feasible or cost-effective remedial alternative for the eastern part of the site. The results of Phase II Aquifer Testing are documented in the Phase I Aquifer Testing at Allegany Ballistics Laboratory Swper/wnd Site Report (CH2M HILL, September 1999).

Focused Feasibility Study for Groundwater (FFS) Based upon the information gathered during all previous investigations, an FFS was conducted to develop and evaluate remedial alternatives for Site 10 groundwater contamination. Thie following remedial action objectives (RAOs) were used in the development and screening processes:

• Prevent or minimize exposure of potential future residents and constiuction workers at the site to contaminated groundwater

• Restore the contaminated aquifers to beneficial use, where practical

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2 - D E C I S I O N SUMMARY

The various altemative.s developed and screened during the Site 10 FFS are discussed in detail in the Focused Feasibility Study for Site 10 Groundwater at Allegany Ballistics Laboratory Swper/wnd Site Report (CH2M HILL, March 1998).

Site 10 Groundwater Interim Remedial Action An interim remedial action was implemented to prevent continued movement of the most highly contaminated portion of the groundwater at Site 10 (referred to as the "hot spot") while other remedial alternatives were evaluated for the rest of the groundwater contamination at the site. A Public Notice was issued and an interim Proposed Plan was provided for public review and comment in March 1998. A Public Meeting was held on April 8,1998 to discuss the proposed interim remedial action and address any comments or concems from the community members.

In June 1998, the interim remedial action ROD was signed by the Navy, EPA, and WVDEP. In February 1999, three alluvial extiaction wells installed within the groundwater "hot spot" at Site 10 were activated and began pumping contaminated groundwater to the Site 1 groundwater tieatnient plant. It was not possible to propose a final remedy at Site 10 in June 1998 because the extent of groundwater contamination had not been determined.

In February 2003, relying oh the results of the Phase III Aquifer Testing, discussed below, the interim remedial action was expanded to install additional exfraction wells and associated piping from Site 10 to the Site 1 to allow exfraction of alluvial and bedrock groundwater throughout Site 10 with subsequent tieatment at the Site 1 groundwater tieatment plant. Site-wide groundwater extiaction is currentiy being achieved through the use of the tiiree alluvial extiaction wells (i.e., 10EW35,10EW36, and 10EW37), plus tiie addition of another alluvial exfraction well (i.e., 10EW38) and four bedrock extiaction weUs (i.e., 10EW39,10EW40,10EW41, and 10EW42). The four bedrock exfraction wells were created by converting three existing bedrock monitoring wells (i.e., lOGWOl, 10GW03, and 10GW19) and former plant production well PWC into extiaction wells. Figure 2-6 shows the locations of the exfraction wells.

New discharge piping was installed for the newly added exfraction wells and joined with the existing header piping at Site 10 to fransport the exfracted groundwater to the Site 1 freatment plant. Treated groundwater from the Site 1 freatment plant currentiy is being discharged to the Nprth Branch Potomac River or is made available for use by ABL's steam generation facility as boiler make-up water.

Phase III Aquifer Testing Since the Site 10 groundwater extiaction system became operational in February 1999, ai number of activities have been conducted at the site to evaluate not only the performance of the remediation system, but also how contaminated groundwater outside of the "hot spot" might best be addressed: Long-term groundwater monitoring, consisting of water-level measurements collected monthly in all Site 10 wells and groundwater samples collected every nine months in a select number of Site 10 wells, has provided an ongoing means of system evaluation since 1999. All other evaluation activities that have taken place at the site since February 1999 have been grouped together in a collective effort referred to as Phase III Aquifer Testing.

Monthly water-level measurements, collected as part of the long-term monitoring program, showed that the three existing alluvial extiaction wells were capturing the "hot spot" contamination and the majority of the remaining groundwater contamination in the alluvial

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2 - DECISION SUMMARY

aquifer. Therefore, as part of Phase III Aquifer Testing, the optimal location for a fourth alluvial exfraction well to maximize groundwater capture was determined, and the well was installed. This fourth exfraction well, working in conjunction with the existing three exfraction wells and made operational as an expansion of the interim remedy, is anticipated to capture all of the alluvial-aquifer groimdwater contamination above the EPA maximum contaminant levels (MCLs).

When the alluvial extiaction system at Site 10 was activated in February 1999, it was believed that any bedrock groundwater contamination at Site 10 would be pulled up into the alluvial aquifer and captured by the alluvial exfraction wells; therefore, no bedrock extiaction wells were installed at that time. The assumption that the alluvial extiaction wells would capture the bedrock contamination was based on historical water-level measurements that showed an upward hydraulic gradient between the bedrock and alluvium at Site 10. However, long-term monitoring and Phase III Aquifer Testing activities conducted since then have shown that bedrock groundwater extiaction at Site 1 is affecting the ability of the existing Site 10 groundwater extiaction system to capture the bedrock contamination there. The long-term monitoring data collected after the Site 1 groundwater extiaction wells were put into operation in September 1998 have shown there to be a hydraulic gradient reversal (i.e., from upward to downward) between the alluvial and bedrock aquifers at Site 10. In addition, a large-scale aquifer test conducted in 2001 showed that pumping the bedrock wells at Site 1 resulted in a water-level decline in bedrock wells at Site 10. Thus, it has been concluded that the Site 1 groundwater extiaction has drawn groundwater from the Site 10 bedrock away from the Site 10 alluvial wells and toward the Site 1 wells.

Based on the results of the large-scale test conducted in 2001, a groundwater computer model was developed to simulate the hydraulic relationship between Site 1 and Site 10 and to determine the most effective way of overcoming the influence of groundwater pumping at Site 1 on the water levels at Site 10.

The results of the large-scale test and the groundwater computer model development and simulations are documented in the Phase III Aquifer Testing at Site 1 and Site 10 of Allegany Ballistics Laboratory.Superfimd Site Report (CH2M HILL, March 2002). The results of the Phase III Aquifer Testing, especially the groundwater computer modeling results, form the basis for the expansion of the interim remedy as well as the selected remedy.

2.2.3 CERCLA Enforcement Activities No CERCLA enforcement activities have occurred at Site 10.

2.3 Community Participation The Navy, as lead agency for Site 10, has m^t the public participation requfrements established in Section 300.430(f)(3) of the NCP as follows:

• The notice of availability of the Proposed Remedial Action Plan (PRAP) for Site 10 Groundwater was published in the Mineral Daily News Tribune on January 16, 2002 and in the Cumberland Times-New? on January 17, 2002The Navy held the public comment period on tiie Site 10 Groundwater PRAP from January 30, 2002 to March 16, 2002.

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2-DECISION SUMMARY

• The Site 10 Administiative Record file (i.e., the PRAP and supporting documents related to Site 10) was made available to the public at the following information repositories:

La Vale Public Library ' La Vale, Maryland

Fort Ashby Public Library Fort Ashby, West Virginia

• The Navy held a Public Meeting on February 13, 2002 to explain the PRAP and to address public conunents. A franscript of the meeting was prepared by Court Reporters, ETCetera, Inc. and has been added to the Site 10 Administiative Record in the public information repositories and is included as Appendix A to this ROD.

• Verbal questions and comments were received during the Public Meeting and written comments were received during the public comment period. Substantive questions and comments were reviewed, and the Navy's responses are presented in the Responsiveness Summary (Section 3 of this ROD).

The PRAP indicated that the Navy had selected extiaction of alluvial and bedrock groundwater, tieatment at the Site 1 tieatment plant, long-term groundwater monitoring, and land use restiictions was the selected remedy regarding which public opinion was being sought. Although many questions and comments were received, the public did not object to proceeding with the selected remedy. In February 2003, part of the remedy outiined in the PRAP was undertaken as an expansion of the 1998 Interim ROD.

In addition to the NCP public participation requirements, the Navy and ABL have implemented a comprehensive public involvement program for several years. Starting in 1993, a Technical Review Committee (TRC) would meet on average twice a year to discuss issues related to investigative activities at ABL. Government personnel primarily comprised the TRC; however, the meetings were open to the public and a few private citizens attended the meetings.

In early 1996, the Navy converted the TRC into a Restoration Advisory Board (RAB) and 8 to 10 community representatives joined. The RAB is co-chaired by a community member and holds nrieetings, which are open to. the public, approximately every three months.

To help meet the needs of the local community for information about, and participation in, the ongoing investigative and remedial processes at ABL, the Navy developed a Community Relations Plan (CRP) in 1994 and updated it in 2001. The CRP identifies community concems about the investigation and restoration of potentially contaminated sites at ABL and outiines conununity 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 concems and the effectiveness of public participation activities to date, which were obtained during interviews with members of the local community.

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2.4 Scope and Role of Operable Unit or Response Action Site 10 is one of several sites identified in the Federal Facility Agreement (FFA) for ABL. A list of all sites can be found in the Site Management Plan (SMP) for ABL (Cli2M HILL, April 2004). Over the last seven years, RODs have been signed for four sites at ABL in accordance with the priorities established in the SMP.

Remedies have been implemented at 4 of the 12 top priority sites at ABL. The designation, media, and remedial action for each site are listed below:

• Site 1 Groundwater, Surface Water, and Sediinent (OU 3): site-wide groundwater extiaction and tieatment (ROD May 1997)

• Site 5 Landfill Contents and Surface Soil (OU 1): capping (ROD January 1997)

• Site 7 Former Beryllium Landfill (OU 7): landfill contents removal in 1997 (No Further Action ROD September 2001)

• Site 10 Groundwater (OU 5): focused groundwater extiaction and freatment (Interim ROD June 1998)

Similar to Site 1, the nature and extent of contamination in media at Site 10 are complex. As. a result, the Navy has organized the work into two OUs:

• OU 5: contaminated groundwater at Site 10

• OU 6: contaminated soil at Site 10

Contamination associated with Site 10 groundwater (OU 5), the subject of this ROD, currentiy is under an interim remedial action where "hot spot" containment was the irdtial primary objective. This objective is being met through focused groundwater extiaction from the most contaminated portion of the alluvial aquifer and freatment at the Site 1 groundvyater freatment plant. However, based on the existing COPC levels, future use of groundwater at Site 10 still poses a potential risk to human health because EPA's acceptable risk values are exceeded and concentiations of contaminants are greater than MCLs (as specified in the Safe Drinking Water Act). Therefore, the interim remedial action was expanded to allow for greater groundwater exfraction and tieatment. This ROD adopts the expansion of the interim remedial action and otherwise presents the final response action for OU 5 to adequately address this risk.

This respor\se action considers contaminated soil in the vicinity of the former TCE still to be the source material and wiU be consistent with any final action proposed for Site 10 soil (OU 6). Contamination associated with Site 10 soil is still under investigation and will be addressed in a future PRAP and ROD.

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2-DECISION SUMMARY

2.5 Site Characteristics

2.5.1 Site Overview Site 10 is located in the south-cenfral area of the developed portion of Plant 1, approximately 2,000 feet from North Branch Potomac River (Figure 2-1). The site is relatively flat, with land elevations between about 665 feet above mean sea level (amsl) and 671 feet amsl. Land use immediately around Site 10 is industiial, with undeveloped mountainous woodland to the south and east and several residences and farmland across the river to the north and west. The majority of the site is grass-covered, but a significant portion is covered by facility buildings and roads. There are no areas of archeological or historical importance at Site 10. Defining the site by the region of groundwater contamination attributed to the former TCE still, its area is approximately 20 to 25 acres.

Site 10 is underlain by two distinct geologic units: (1) unconsolidated alluvial deposits of clay, silt, sand, and gravel and (2) predominantiy shale bedrock. The unconsolidated alluviail deposits overlying bedrock generally 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. The alluvium has an average thickness of approximately 14.5 feet at Site 10.

The average depth to bedrock at Site 10 is approximately 23 feet and samples of the bedrock collected there indicate it consists mainly of calcareous shale but with some limestone. Site 10 is believed to be in a zone where the bedrock was highly folded and faulted when the moimtains were being formed.

The lower portion of the unconsolidated material is saturated and represents the unconfined alluyial aquifer at the site. Immediately below and directiy connected with the alluvial aquifer is the bedrock aquifer. The results of aquifer testing conducted at Site 10 suggest the bedrock aquifer exhibits leaky (i.e., serni-confined) characteristics. Although small-scale variations in groundwater flow exist at Site 10, the predominant flow direction in both the alluvial and bedrock aquifers is northeast toward the North Branch Potomac River, which is the predominant hydrologic feature in the vicinity of the site.

Historical water-level data suggest that both the alluvial and bedrock groundwater at Site 10 preferentially flow through a relatively narrow zone in the northeastern portion of the site. It is believed that this zone represents ah area where the bedrock is more highly fractured than its surroundings and, therefore, channels groundwater toward the northeast. Information gathered since the groundwater extiaction system at Site 1 has been operational suggests that much of the groundwater migrating toward the northeast downgradient of Site 10 is intercepted by the Site 1 exfraction system before it can reach the river.

The Conceptual Site Model (CSM) for contaminated groundwater at Site 10 is shown in Figure 2-3. The CSM Ulusfrates that the suspected source of groundwater contamination was the former TCE still and that contamination resulting from spills percolated through the soil and contaminated the underlying groundwater. The CSM also shows the potential receptors for the contaminated groundwater. The potential risks posed by the contaminated groundwater to these receptors are discussed in Section 2.7.

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2 —DECISION SUMMARY

2.5.2 Sampling Strategy Information about Site 10 media has been gathered from the numerous soil and groundwater samples that have been collected at the site since the Interim RI (see chronology of investigations in Section 2.2.2). The majority of groundwater samples have been collected from three alluvial exfraction wells and over thirty monitoring wells in and around the site. Screening-level groundwater sampling has also been conducted at the site using direct-push technology for plume delineation purposes. See Section 2.5.4 for a discussion of the sample results.

2.5.3 Source of Contamination \ The suspected source of contamination in groundwater at Site 10 was spills and leaks from the former TCE still located outside of Building 157. Degreasing and distilling activities involving TCE Were conducted at the building for only a few years begirming about 1960.

2.5.4 Nature and Extent of Ctiemicals in Site 10 Groundwater Data collected during the various investigations conducted (see Section 2.2.2) have well-defined the area of groundwater contamination in the alluvial and bedrock aquifers at Site 10. VOCs detected in Site 10 groundwater have been attributed to the former TCE stiU activities and are the primary COPCs identified for groundwater at the site. Based on VOC concentiations. detected to date in alluvial and bedrock groundwater, dense non-aqueous phase liquids are not expected to be present at Site 10. Inorganic constituents have also been detected at Site 10, but inorganics are ubiquitous to groundwater and the concentiations detected at Site 10 are similar to those found elsewhere at the facility. Although arsenic and manganese were identified in the Phase II RI HHRA as COPCs, arsenic has not been detected during the more recent long-term monitoring program and the Concentiations of manganese detected during long-term monitoring generally have been below the maximum value used in the risk assessment and similar to those found elsewhere at ABL.

Of the VOCs detected in Site 10 groundwater during the long-term monitoring program, TCE; tetiachIoroeti\ene (PCE); 1,1-dichIoroetiiene (1,1-DCE); 1,2-dichloroetiiene (total) (1,2-DCE); and 1,1,1-frichloroethane (1,1,1-TCA) are the most prevalent. The concenfrations of these five VOCs measured during the May 2001 long-term monitoring event are graphically depicted for the Site 10 alluvial and bedrock aquifers in Figures 2-4 and 2-5, respectively. During that event, TCE and PCE were the only VOCs detected above their respective MCLs. The approximate areas of TCE in groundwater above its MCL of 5 ^ig/l are depicted in Figures 2-4 and 2-5.

Figures 2-4 and 2-5 provide an approximation of the lateral and vertical extent of VOC contamination in groundwater at Site 10. Both figures show that the area of contaminated groundwater is elongated in a northeast direction from the former TCE still at Building 157, which is coincident with the direction of natural groundwater flow. Figure 2-5 shows that the area of contaminated groundwater in the bedrock also is elongated toward the south, which is attributed to historical pumping of bedrock PWA.

Of the VOCs listed above, TCE; PCE; 1,1-DCE; and 1,2-DCE (total) were selected as COPCs for the HHRA conducted during the Phase 11 RI. Methylene chloride was also selected, but this constituent was not detected in any of the Site 10 monitoring wells during the May 2001

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2-DECISION SUMMARY

long-term monitoring event. Of the VOCs detected in Site 10 groundwater, TCE is most predominant in terms of distribution and concentiations. In fact, TCE accounts for the majority of the calculated human exposure risk; its calculated hazard quotient generally was an order of magnitude higher than those of the other VOCs.

Based on the results of the large-scale test conducted in 2001 (Phase III Aquifer Testing), a groundwater computer model, using MODFLOW®, was developed to simulate groundwater flow at and away from Site 10, including between the alluvial and bedrock aquifers. This model was used to help determine the optimal location of additional extiaction wells to contain and remove groundwater contamination at Site 10.

2.6 Current and Potential Future Site and Resource Uses

2.6.1 Current and Potential Future Site Uses As noted in Section 2.1, Site 10 is located in the south-cential area of the developed portion of Plant 1. As such, the current land use at the site and adjacent areas is industrial. The Navy anticipates that this area will remain under its ownership and continue in the same capacity for the foreseeable future. Therefore, access to the site will continue to be restiicted by fencing and security personnel.

Although the current site use is expected to continue into the foreseeable future, its conversion to residential use was considered feasible for the purpose of evaluating potential futurie human health risks.

In accordance with Section 22-18-21 of the West Virginia Code, a notation will be filed as a separate notice v^th the ABL Plant 1 property deed that indicates Site 10 historically managed hazardous waste. This notation does not dispose, alienate, or encumber any real property interests held by the United States and creates no independent enforcement authority in the State of West Virginia or any third parties.

2.6.2 Current and Potential Future Groundwater and Surface Water Uses As noted in Section 2.5, there are no perennial surface water bodies at Site 10; the closest perennial surface water body is the North Branch Potomac River, which is approximately 2,000 feet north of the site.

The closest potable groundwater production wells to Site 10 are more than a mile to the southwest. Currentiy, the only groundwater extiacted at Site 10 is for the interim remedial action. All exfracted groundwater is tieated at the Site 1 groundwater freatment plant. A portion of the tieated water is used by the facility's steam generation plant as boiler makeup water. The remainder of the tieated water is discharged to the North Branch Potomac River.

If the facility is converted to residential use in the future, it is possible that bedrock groundwater at Site 10 could be used as a potable water source. This assumption was used to estimate potential human health risks from exposure to Site 10 groundwater in the Phase II RI. In addition, as presented in Section 2.8, one of the RAOs for Site 10 groundwater is to restore the contaminated aquifers to beneficial use, where practical. For cost estimating

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2-DECISION SUMMARY

purposes, it was assumed that 30 years would be.required to attain the acceptable groundwater levels for use as a potable source.

2.7 Summary of Site Risks A baseline HHRA and ERA were conducted for Site 10 during the Phase II RI. A baseline risk assessment estimates what potential risks contamination at a site poses if no remedial action is taken. It provides a basis for taking action and identifies the contaminants and exposure pathways that need to be addressed by the remedial action. This section of the ROD summarizes the results of these baseline risk assessments as they pertain to Site 10 groundwater. A more detailed discussion of the baseline HHRA and ERA can be found in sections 8 and 9, respectively, of the Phase II Remedial Investigation at Allegany Ballistics Laboratory, Rocket Center, West Virginia Report (CH2M-HILL, August 1996).

2.7.1 Summary of Human Health RisIt Assessment Overall risks to human health are evaluated based on a conservative estimate of the potential cancer-causing (carcinogenic) risks and other potential health effects not related to cancer. These risk evaluations are made using EPA guidance to ensure that conservative estimates are obtained, using known current land use and the possible future land use scenarios. A brief description of how human health risk is evaluated is summarized below. The outcome of the HHRA conducted for Site 10 groundwater is then provided in the

-subsequent subsections.

Cancer risks are expressed as numbers reflecting the increased chance that a person will develop cancer if he/she is directiy exposed (for example, through working, playing, or living at the site) to contamination over a period of time. EPA's acceptable cancer risk range is 1x10-* to 1x10-6, or a one additional chance in ten thousand (1x10^) to a one additional chance in one million (1x10-*) that a person will develop cancer over a lifetime of exposure to the contamination. Non-cancer risks are expressed as a hazard index (HI), which is the ratio of the existing (or possible) level of exposure to contamination to an acceptable level of exposure. Adverse health effects to exposure are not expected if the calculated HI is equal to or less thanl . \

The baseline HHRA for Site 10 evaluatied potential risks to people from coming in contact with contaminated groundwater for a future residential scenario, which is the most conservative of the future use scenarios. Groundwater at Site 10 currentiy is not used as a potable source; therefore, there are no current exposure scenarios.

2.7.1.1 Identification of Chemicals of Potential Concem (COPCs)

The COPCs and the exposure point concentiations and frequency of detection for each of the COPCs are sunimarized in Table 2-1. Seven COPCs were identified for Site 10 groundwater. Because of the limited amount of sample data available at the time the HHRA was conducted, the maximum concenfration was used as the default exposure point concenfration for each of the COPCs.

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2.7.1.2 Exposure Assessment

Exposure assessment is the determination or estimation (qualitative or quantitative) of the ' magnitude, frequency, duration, and route of exposure of potential receptors to contaminated media: Human exposure to chemicals in groundwater can occur through ingestion of groundwater by drinking or eating, dermal contact during bathing, or inhalation of VOCs volatilized from groundwater during showering. The site conceptual model is shown in Figure 2-3 and the exposure pathways for Site 10 groundwater evaluated in the HHRA are summarized in Table 2-2.

Currentiy, ABL obtains potable water from supply wells that are located more than a mile from Site 10. The only groundwater withdrawal from Site 10 is by exfraction weUs that are part of the interim remedial action. Because no current groundwater exposure pathway exists, a current groundwater exposure scenario for onsite workers and construction workers was not evaluated quantitatively.

Of the potential future land use scenarios, future resident, the most conservative of the various future scenarios, was selected for the HHRA. For the future resident, bedrock groundwater use is the most likely groundwater exposure scenario. Although the alluvial aquifer at Site 10 likely carmot sustain a sufficient yield for use as a potable water sotirce, contact with the alluvial aquifer was evaluated as a conservative reasonable maximum exposure scenario because higher levels of contamination have been found in the alluvial aquifer than the bedrock aquifer at Site 10. For both of these hypothetical future groundwater supply scenarios, the exposures that were quantified were ingestion of chemicals in groundwater (children and adults), dermal contact with groundwater during bathing (children only), and inhalation of VOCs during showering (adults only). The . approach used to estimate the inhalation exposure to VOCs in groundwater was based on the model by Foster and Chrostowski (1987). The exposure factors for child and adult residents that were used in the baseline HHRA are summarized in Table 2-3.

2.7.1.3 Toxicity Assessment

The purpose of a toxicity assessment is to examine the available evidence regarding the potential for particular contaminants to cause adverse effects in exposed individuals and to provide/where possible, an estimate of the relationship between the extent of exposure to a contaminant and the increased likelihood or severity of adverse effects. When assessing human health risks, health effects are divided into two broad groups (i.e., non-cancer and cancer) that are evaluated independentiy. However, some constituents have both non-cancer and cancer effects and are therefore considered in both groups (e.g., arsenic).

For carcinogens, risk is evaluated as the incremental probability of an individual developing cancer over a lifetime as a result of exposures to the carcinogen. Excess lifetime cancer risk is calculated from the following equation:

Risk = CDIxSF

where: Risk = the probability (e.g., 2 x 10- ) of an individual developing cancer CDI = chronic daily intake averaged over 70 years (mg/kg*day) SF = slope factor (mg/kg*day)-i

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2 -DECIS ION SUMMARY

These risks are probabilities that usually are expressed in scientific notation (e.g., 1 x 10-*). An excess lifetime cancer risk of 1 x 10-* indicates that an individual experiencing the reasonable maximum exposure estimate has a 1 in 1,000,000 chance of developing cancer as a result 6f site-related exposure. This risk estimate is referred to as an "excess lifetime cancer risk" because the cancer risk is in addition to all the other cancer risks (e.g., smoking, etc.). EPA's acceptable risk range for site-related exposures is 10^ to 10-*.

The potential for non-carcinogenic effects is evaluated by comparing an exposure level over a specified period of time with a reference dose (RfD) derived for a similar exposure period (i.e., chronic, sub-chronic, or short term). An RfD represents a level that an individual may be exposed to that is not expected to cause any deleterious effects. The ratio of the exposure (actual or potential) to the RfD is the hazard quotient (HQ), which is how non-cancer risk posed by an individual chemical is expressed. An HQ less than 1 indicates that noncarcinogenic effects from exposure to the chemical are unlikely. Non-carcinogenic effects are likely if the HQ is greater than 1. The HQ is calculated as follows:'

HQ = CDI/RfD

where: CDI = chronic daily intake RfD = reference dose

The HI is the cumulative non-cancer effect and is generated by adding the HQs for all COPCs that affect the same target organ (e.g., liver) or act through the same mechanism in a given medium. Similar to the HQ, an HI less than 1 indicates that a cumulative noncarcinogenic effect from all the chemicals is unlikely. Conversely, an Hi greater than 1 represents a potential non-carcinogenic effect from exposure to the chemicals. HI is calculated as follows:

HI = HQi-H HQ2-t-... + HQn

where: n = tiie n* COPC

The toxicity information (i.e., RfDs, SFs, etc.) that was used to calculate cancer and non-cancer risks for the seven COPCs for Site 10 groundwater (Table 2-1) is summarized in Table 2-4. These toxicity values were used to estimate the likelihood of adverse effects occurring in humans at different exposure levels. The toxicity information used in the baseline human health risk assessment was mairUy derived from the Integrated Risk . Information System (IRIS) and Health Effects Assessment Summary Tables (HEAST) databases (IRIS 1995, USEPA 1994). If toxicity values were not available through IRIS or HEAST, the EPA's Environmental Criteria and Assessment Office (ECAO) values were used, where available.

2.7.1.4 Human Health Risk Characterization

The H H R A summary by receptor for Site 10 groundwater is provided in Table 2-5. The results of the baseline HHRA for potential future groundwater users at Site 10 indicate that an unacceptable risk exists for the most likely water supply (in other words, exposure to contaminated bedrock groundwater as the water supply). For this scenario, the cancer-risk (8 X 10-5) is within the EPA acceptable risk range, but the HI for the child resident (1.1) exceeds 1. Furthermore, unacceptable cancer (1.4 x 10:*) and non-cancer (4 for child and 3 for

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adult) risk values were calculated for exposure to contaminated alluvial groundwater as the water supply.

Several sources of tmcertainty are inherent to estimates of excess lifetime cancer risk and non-cancer hazard. These sources are generally associated with:

• Potential sampling and analysis variability and error. Rigorous quality assurance and quality contiol procedures are carried out to reduce this source of uncertainty.

• Potential alternative source(s) of contamination. Evaluation of historical information and assurance of adequate spatial disfribution of sample locations and associated analytical parameters are two methods used to minimize this source of uncertainty.

• Exposure assumptions. Conservative exposure scenarios and exposure-point concentiations are utilized in order to minimize the possibility of underestimating potential risk.

• Toxicity of COPCs. Uncertainty in toxicity derives from a number of sources, including exfrapolation from animals to humans and variability in humans (e.g., gender, age, diet, hereditary factors, etc.). Additionally, some chen\icals have no published toxicity information.

• Methods for calculating cancer and non-cancer risks. Assumptions used in the risk calculations have uncertainty associated with them (e.g., RfDs, summation of individual HQs, etc.)

2.7.2 Summary of Ecological Risk Assessment For there to be an ecological risk at a site, there must be a source of contamination and a pathway for exposure to the contaminants. Based upon the baseline ERA, although there is a potential source of contamination (contaminated soil), there is no complete exposure pathways for plants and animals to come in contact with contaminated groundwater at the site. Therefore, the potential ecological risk from Site 10 groundwater contamination is considered to be within acceptable limits.

2.7.3 Basis for Action Based on the HHRA and ERA, the reisponse action selected in this ROD is necessary to protect the public health or welfare or the envfronment from actual or threatened releases of hazardous substances, pollutants, or contaminants in groundwater at Site 10.

2.8 Remedial Action Objectives (RAOs) The NCP requires that a selected remedy at any site meet certain objectives. These objectives are summarized below:

• Be protective of human health and the environment

• Attain applicable or relevant and appropriate requirements (ARARs) identified in the ROD

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• Be cost-effective

• Use permanent solutions and alternative freatment technologies or resource-recovery technologies to the maximum extent practicable

The statutory scope of CERCLA was amended by Superfund Amendments and Authorization Act to include the following general objectives for remiedial action at all CERCLA sites:

• "[AJttain a degree of cleanup of hazardous substances, pollutants, and contaminants released into the environment and of contiol of further release at a minimum which assures protection of human health and the environment." (Section 121(d)(1))

• Utilize "freatment which permanentiy and significantiy reduces the volume, toxicity or mobility'of the hazardous substances, pollutants, and contaminants [as] a principal element" (Section 121(b)(1))

• Discourage "offsite tiansport and disposal of hazardous substances or contaminated materials without freatment... where practicable tieatment technologies are available." (Section 121(b)(1))

• Comply with or attain the level of any "standard, requirement, criteria, or limitation under any Federal environmental law . . . or . . . any promulgated standard, requirement, criteria, or limitation under a State environmental or facility siting law that is more stringent than any Federal standard, requirement, criteria, or limitation . . . . " (Section 121(d)(2)(A))

During the FFS, a detailed analysis of possible remedial alternatives was conducted for Site 10 groundwater. Each remedial alternative was developed to meet the RAOs listed above, as well as specific objectives defined for Site 10 groundwater. The site-specific RAOs developed for Site 10 groimdwater, as modified from the FFS, are:

• Prevent or minimize exposure of potential future onsite residents and constiuction workers to contaminated groundwater originating from Site 10

• Achieve the chemical-specific MCLs, where practicable

In achieving the aforementioned RAOs, the remedial action selected for Site 10 groundwater will adequately address the potential risks, identified in the baseline HHRA.

2.9 Description of Alternatives " . .

The following ten groundwater remedial alternatives were developed in the Site 10 FFS (CH2M HILL, March 1998):

• Alternative 1: No action

• Alternative 2: Institutional contiols and natural attenuation

• Alternative 3: Site-wide groundwater exfraction and discharge to the Site 1 freatment plant

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2-DECISION SUMMARY

Alternative 4: Site-wide groundwater exfraction, air stiipping, and discharge to the storm sewer

Alternative 5: Site-wide groundwater extiaction, carbon adsorption, and discharge to the storm sewer •

Alternative 6: Site-wide groundwater exfraction, ulfraviolet/hydrogen peroxide oxidation, and discharge to the storm sewer

Alternative 7: Site-wide groundwater extiaction, air stiipping, and reinjection

Alternative 8: Focused groundwater exfraction, air stiipping, and discharge to the storm sewer

Alternative 9: Focused groundwater extiaction and discharge to the Site 1. freatment plant

Alternative 10: Focused groundwater extiaction, air stiipping, and reinjection

Of these ten remedial alternatives, alternatives 2,5, 6, 7, and 10 were eliminated in the initial screening step because they could not achieve the RAOs or were not cost effective relative to the other alternatives.

Alternatives 1,3,4,8, and 9 were carried through the detailed screening process. This section of the ROD summarizes these five groundwater remedial alternatives, modified as appropriate with the information gathered since the Site 10 FFS was produced. The modifications comprise adjustments made to the operation and maintenance (O&M) and long-term monitoring costs based on actual costs incurred during the interim remedial action period and adjustments made to capital costs based on the revised number of extiaction wells determined to be necessary. These cost modifications are presented in detail in Appendbc E of tiie Phase III Aquifer Testing Report (CH2M HILL, January 2002).

2.9.1 Description of Remedial Alternatives Major components of each remedial alternative are provided in the following subsections.

2.9.1.1 Altemativel: No Action

The no-action alternative is required to be evaluated by the NCP and serves as the baseline alternative agauist which all other remedial action alternatives are judged. Under this alternative, no additional actions would be implemented to reduce the potential risks associated with Site 10 groundwater contamination and the RAOs would not be met. No monitoring of groundwater contamination would be performed to verify if the concentiations have reached acceptable concentiations and to determine whether additional remedial action is needed in the future. With the exception of the 5-year review, required by Section 121(c) of CERCLA if a remedial action allows contamination to remain onsite, there are no capital or O&M costs associated with this alternative.

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2.9.1.2 Alternative 3: Site-wide Groundwater Extraction and Discharge to the Site 1 Treatment Plant

Under this alternative, site-wide alluvial and bedrock groundwater exfraction will occur with subsequent freatment at the Site 1 groundwater freatment plant. The major components of this alternative are:

• Groundwater use restiictions imposed through appropriate administiative mechanisms until the RAOs for OU 5 are achieved

• Groundwater exfraction from four alluvial extiaction wells and four bedrock extiaction wells

• Modification of the pipeline installed for the interim remedial action to fransport groundwater froiri Site 10 to the Site 1 freatment plant

• Discharge of the freated groundwater to the North Branch Potomac River or ABL's steam generation plant

• Groundwater monitoring in accordance with the long-term monitoring plan to evaluate groundwater quality, contaminant migration, and remedial system performance for inclusion in 5-year reviews. The long-term monitoring plan is developed by the Navy and approved by the EPA and W V D E P .

This is the existing interim remedial aiction at Site 10 and would not require any additional capital cost. Therefore, the estimated costs to continue this alternative are:

Capital O&M Long-term monitoring

$0 $1,580,000 $950,000

Net present worth (30-year) $2,530,000

2.9.1.3 Alternative 4: Site-wide Groundwater Extraction, Air Stripping, and Discharge to the Storm Sewer

Under this alternative, site-wide alluvial and bedrock groundwater exfraction will occur with subsequent tieatment at a groimdwater tieatment plant constructed at Site 10. The major components of this alternative are:

• Groundwater use restiictions imposed through appropriate administiative mechanisms until the RAOs are achieved

• Groundwater extiaction from four alluvial exfraction wells and four bedrock extiaction wells

• Constiuction of a tieatment system at Site 10 and tieatment of the groundwater by metals sequesfration and afr stiipping

• Discharge of the tieated groundwater to an existing storm sewer that runs adjacent to Site 10 and discharges to the North Branch Potomac River

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2-DECISION SUMMARY

• Groundwater monitoring in accordance with the long-term monitoring plan to evaluate groundwater quality, contaminant migration, and remedial system performance for inclusion in 5-year reviews. The long-term monitoring plan is developed by the Navy and aipproved by the EPA and WVDEP.

The estimated costs to implement Alternative 4, as modified from the Site 10 FFS, are:


$470,000 $3,510,000 $950,000

Net present worth (30-year) $4,930,000

The estimated implementation time for Alternative 4 is 4 to 5 months.

2.9.1.4 Alternative 8: Focused Groundwater Extraction, Air Stripping, and Discharge to the Storm Sewer

Under this alternative, focused alluvial groimdwater extiaction wiU occur with subsequent freatment at a groundwater freatment plant constiucted at Site 10. The major components of this alternative are:

• Groundwater use restiictions imposed through appropriate administiative mechanisms until the RAOs are achieved

• Extiaction from three existing alluvial wells to capture the "hot spot" of the VOC , contaminant plume with the remainder of the alluvial plume and all of the bedrock

plume being remediated by natural attenuation

• Constiuction of a freatment system at Site 10 and freatment of the groundwater by metals sequesfration and air stiipping

• Discharge of the tieated groundwater to an existing storm sewer that runs adjacent to Site 10 and discharges to the North Branch Potomac River

• Groundwater monitoring in accordance with the long-term monitoring plan to evaluate groundwater quality, contaminant migration and degradation, and remedial system performance for inclusion in 5-year reviews. The long-term monitoring plan is developed by the Navy and approved by the EPA and WVDEP.

The estimated costs to implement Alternative 8, as modified by the Site 10 FFS, are:


$340;000 , $1,310,000

$950,000

Net present wortii (30-year) $2,600,000

The estimated implementation time for Alternative 8 is 4 to 5 months.

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2.9.1.5 Alternative 9: Focused Groundwater Extraction and Discharge to the Site 1 Treatment Plant

Under this alternative, focused alluvial groundwater extiaction will occur with subsequent groundwater tieatment at the Site 1 tieatinent plant. The major components of this alternative are:

• Groundwater use restiictions imposed through appropriate adminisfrative mechanisms until the RAOs are achieved

• Extiaction from three existing alluvial wells to capture the "hot spot" of the VOC contaminant plume with the remainder of the plume and all of the bedrock plume being remediated by natural attenuation

• Installation of a pipeline to tiansport groundwater from Site 10 to the Site 1 tieatment plant

• Discharge of the tieated groundwater to the North Branch Potomac River or ABL's steam generation plant

• Groundwater monitoring in accordance with the long-term monitoring plan to evaluate groundwater quality, contaminant migration and degradation, and remedial system performance for inclusion in 5-year reviews. The long-term monitoring plan is developed by the Navy and approved by the EPA and WVDEP.

This alternative is the initial interim remedial action at Site 10 and would not have required any additional capital costs. Therefore, the estimated costs at the time of the FFS to continue this alternative were:


$0 $1,350,000 $950,000

Net present wortii (30-year) $2,300,000

2.9.2 Common Elements and Distinguisliing Features of Each Alternative With the exception of the "no action" alternative (Alternative 1), all of the remedial alternatives described above have in common groundwater extiaction and tieatment, compliance with the ARARs, long-term reliability; and estimated time to reach cleanup levels. Other common elements and distinguishing features are summarized below:

• Alternatives 3 and 4 provide for site-wide groundwater extiaction from the alluvial and bedrock aquifers

• Alternatives 8 and 9 provide for focused alluvial groundwater extiaction for the plume "hot spot" and rely on natural attenuation for the rernainder of the plume

• Alternatives 3 and 9 utilize the existing freatment plant at Site 1

• Alternatives 4 and 8 require constiuction of a new tieatment facility at Site 10

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The distinguishing feature for Alternative 3 is that it is a combination of the most advantageous elements—site-wide groundwater extiaction rather than reliance on natural attenuation for a portion of the plume, and use of the existing groundwater tieatment plant rather than constiuction of a new one.

2.9.3 Expected Outcomes of Each Alternative Under all alternatives, except the "no action" alternative, it is anticipated that groundwater will be remediated to a level that achieves unrestricted residential use. The time required for this cleanup is assumed to be 30 years. However, because of the uncertainties of the duration of natural attenuation. Alternatives 8 and 9 may require additional time to achieve levels for unrestricted groundwater use.

2.10 Summary of Comparative Analysis of Alternatives The NCP outiines the approach for comparing remedial alternatives. Evaluation of the alternatives uses nine evaluation criteria that are grouped into three broad criteria categories: "threshold," "primary balancing," and "modifying" criteria. All alternatives are first evaluated against the threshold and primary balancing criteria, which are technical criteria based on environmental protection, cost, and engineering feasibility.

To be considered for remedy selection, an alternative must meet the two following threshold criteria:

1. Overall protection of human health and the environment

2. Compliance with ARARs and to-be-considered (TBC) criteria

The primary balancing criteria are then considered to determine which alternative provides the best combination of attiibutes. The primary balancing criteria are:

3. Long-term effectiveness and permanence

4. Reduction in toxicity, mobility, or volume through tieatment

5. Short-term effectiveness

6. Implementability

7. Cost

The alternatives are evaluated further against the two modifying criteria:

8. Acceptance by the State

9. Acceptance by the community •

The comparison of each of the five remedial alternatives is summarized by criteria below.

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2.10.1 Threshold Criteria

2.10.1.1 Overall Protection of Human Health and the Environment

Overall protection of human health and the environment addresses whether each alternative provides adequate protection of human health and the environment and describes how risks posed through each exposure pathway are eliminated, reduced, or contiolled, through freatment, engineering controls, and/or institutional contiols.

All of the alternatives, except the "no action" alternative, are protective of human health and the envfronment from groundwater contamination at Site 10. Alternatives 3 and 4 are most protective because they provide for site-wide groundwater extiaction from both the alluvial and bedrock aquifers and do not rely upon natural attenuation for contaminant reduction as do Alternatives 8 and 9. However, all four of these alternatives include the same groundwater use restiictions to minimize potential human exposure to the groundwater until the RAOs are achieved.

2.10.1.2 Compliance with Applicable or Relevant and Appropriate Requirements

Section 121(d) of CERCLA and N C P 300.430(f)(l)(ii)(B) requfre tiiat remedial actions at CERCLA sites at least attain legally applicable or relevant and appropriate Federal and State requirements, standards, criteria, and limitations, which are collectively referred to as "ARARs," unless such ARARs are waived under CERCLA section 121(d)(4). The ARARs identified for the remedial actions at Site 10 are listed in Table 2-8.

"Applicable requirements" are those cleanup standards, standards of contiol, and other, substantive requirements, criteria, or limitations promulgated under Federal envfrorunental or State enviroiunental or facility-siting laws that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance found at a CERCLA site. Only those State standards that are identified by a state in a timely manner and tha;t are more stringent than Federal requirements may be applicable. "Relevant and appropriate requirements" are those cleanup standards, standards of contiol, and other substantive requirements, criteria, or limitations promulgated under Federal envfrorunental or State environmental or facility-siting laws that, while not "applicable" to a hazardous substance, pollutarit, contaminant, remedial action, location, or other circumstances at a CERCLA site, address problems or situations sufficientiy similar to those encountered at the CERCLA site that their use is well-suited to the particular site. Only those State standards that are identified in a tifriely manner and are more stringent than Federal requfrements may be relevant and appropriate.

In addition, the NCP, at 40 CFR § 300.400(g)(3), invites the lead agency to identify criteria or guidance to be considered (TBC) in deciding upon implementation of a remedial action. TBCs are guidance, advisories, or criteria developed by EPA, other federal agencies or states that may be useful in developing a CERCLA remedy; however, TBCs are not promulgated rules or laws.

Compliance with ARARs addresses whether a remedy will meet all of the applicable or relevant and appropriate requfrements of other Federal and State environmental statutes or provides a basis for invoking a waiver.

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All of the alternatives, except the "no action" alternative, are anticipated to meet the ARARs established for Site 10 groundwater. In general. Alternatives 3 and 4 have a higher level of certainty in meeting the ARARs than Alternatives 8 and 9. For example. Alternatives 3 and 4 will meet the chemical-specific ARARs through groundwater extiaction. On the other hand. Alternatives 8 and 9 rely upon natural attenuation to meet these ARARs for a portion of the contaminant plume.

2.10.2 Primary Balancing Criteria

2.10.2.1 Long-Term Effectiveness and Permanence

Long-term effectiveness and permanence refers to expected residual risk and the ability of a remedy to maintain reliable protection of human health and the envfronment over time, once clean-up levels have been met. This criterion includes the consideration of residual risk that will remain onsite following remediation and the adequacy and reliability of contiols.

All of the alternatives, except the "no action" alternative, are anticipated to achieve long-term effectiveness and permanence. Similar to the ARAR criteria. Alternatives 3 and 4 have a higher level of certainty than Alternatives 8 and 9 because the existence and success of natural attenuation will have to be demonstiated for the latter alternatives.

Review at least every 5 years, as required, would be necessary to evaluate the effectiveness of any of these alternatives until the RAOs are achieved.

2.10.2.2 Reduction of Toxicity, Mobility, or Volume through Treatment

Reduction of toxicity, mobility, or volume through tieatment refers to the anticipated performance of the freatment technologies that may be included as part of a remedy.

All of the alternatives, except the "no action" alternative, utilize tieatment as a component of the remedy. Therefore, all of the alternatives wiU reduce the toxicity and volume of the groundwater contamination. Additionally, Alternatives 3 and 4 will reduce the mobility of the groundwater plume through site-wide groundwater extiaction. Alternatives 8 and 9 will reduce the mobility of the plume "hot spot" through groundwater extiaction, but rely on natural attenuation to reduce the mobility of the remainder of the plurhe.

2.10.2.3 Short-Term Effectiveness

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

Alternatives 1 and 9 can be implemented inpst quickly; however. Alternative 1, the "no action" alternative, does not meet the RAOs. Alternative 9, the existing interim remedial action, has akeady been implemented, but is dependent on natural attenuation for a portion of the contaminant plume. The remaining alternatives can be implemented within 4 to 5 months.

Impact to facility operations will be minimal during implementation of any of the active remedial alternatives. It is possible that installation of the discharge pipeline at Site 10 will cross facility roads. In addition, existing groundwater extiaction at Site 10 will be temporarily interrupted to modify the discharge pipeline.

WDC0209300(M.ZIP 2-22

2-DECISION SUMMARY

With groundwater use restiictions in place until the RAOs are achieved and use of safe work practices, there will be minimal exposure risk to workers or the community during implementation of any of the active remedial actions.

2.10.2.4 Implementability

ImplementabUity addresses the technical and administiative feasibility of a remedy from design through constiuction and operation. Factors such as availability of services and materials, administiative feasibility, and coordination with other governmental entities are also considered. ,

There are no significant technical difficulties associated with implementing any of the alternatives. Alternative 9 is the existing interim remedial action and, therefore, is most easily implemented. Implementing Alternatives 4 and 8 would require design and construction of a new tieatment facility at Site 10. Implementing Alternative 3 would require only a modification to existing wells at Site 10 and discharge piping to the Site 1 freatment plant and is, therefore, more easily implemented than Alternatives 4 and 8.

2.10.2.5 Cost

The estimated present worth costs for the alternatives are listed below:

• Altemative 1: $0 • Altemative 3: $2,500,000 • Altemative 4: $4,900,000 • Altemative 8: $2,600,000 • Altemative 9: $2,300,000

2.10.3 Modifying Criteria

2.10.3.1 state of West Virginia Acceptance

The West Virginia Department of Envfrorunental Protection, on behalf of the State of West Vfrginia, has reviewed the information available for Site 10 groundwater (OU 5) and has concurred with the selected remedy.

2.10.3.1 Community Acceptance

To gauge community acceptance, the public's general response to the alternatives described in the Proposed Plan and the FFS was considered. Several questions and comments were posed at the Public Meeting held on February 13, 2002. A copy of the Public Meeting franscript is provided in Appendix A of this ROD. Substantive questions and comments raised by members of the community during this meeting and by written correspondence are summarized and addressed in the Responisiveness Suinmary presented in Section 3.0.

During the public comment period from Janiiary 30 through March 16, 2002, no comments were received that indicate the public would not accept the selected remedy. Since the public participation phase, a portion of the selected remedy was undertaken as an expansion of the interim remedial action and the completion of the selected remedy will be undertaken pursuant to this ROD. Although the selected remedy in this ROD (continuatiori of site-wide groundwater extiaction and tieatment, land use contiols and long-term

WDC020930004.ZIP ' • 2-23

2-DECISION SUMMARY

monitoring) differs from the selected remedy presented to the public in 2002 (expansion of hot-spot extiaction to site-wide groundwater extiaction, land use contiols and long-term monitoring), the difference is not fundamental and is foreseeable by the public.

2.10.4 Remedial Alternatives Comparative Analysis Summary Table 2-6 summarizes the relative ranking for the alternatives discussed in Section 2.10.

2.11 Principal Threat Waste The NCP (Section 300'.430(a)(l)(iii)(A)) establishes an expectation that EPA will use tieatment to address the principal threats posed by a site wherever practicable. The "principal threat" concept is applied to the characterization of source materials at a Superfund site. A source material is material that includes or contains hazardous substances, pollutants, or contaminants that act as a reservofr for movement of contamination to groundwater, surface water, or air, or acts as a source for dfrect exposure. Contaminated is generally not considered to be a source material, although non-aqueous-phase liquids (NAPL), which can be found in contaminated groundwater, may be a source material. The data collected to date suggest groundwater at Site 10 does not contain NAPLs; therefore, there are no principal threat wastes in Site 10 groundwater. The potential presence of a principal threat waste in Site 10 subsurface soil (OU 6) will be addressed in the final action proposed for OU 6. ,

2.12 Selected Remedy It is important to note that Altemative 9 of the Site 10 FFS was selected as the initial interim remedial action in the interim action ROD signed in June 1998 and that in February 2003, the interim remedial action was expanded to initiate site-wide groundwater extiaction. Based on the continuing evaluation of the interim remedy performance and other related activities, Altemative 3 is selected as the final remedial action.

2.12.1 Summary of the Rationale for the Selected Remedy Alternative 3, site-wide groundwater exfraction and discharge to the Site 1 tieatment plant, is the selected remedy for contaminated groundwater at Site 10. Altemative 3 provides the best balance of the nine NCP evaluation criteria described in Section 2.10. Alternative 3 is the most protective of human health and the environment because it utilizes site-wide groundwater exfraction and tieats the extiacted groundwater so it can be reused as uncontaminated water. Compared to the remaining alternatives. Alternative 3 will achieve ARARs, short- and long-term effectiveness, achievement of contaminant reduction, and implementability. In addition, the cost for Altemative 3 is comparable to the other active remedial alternatives but is more cost effective than some alternatives because it makes use of the Site 1 water tieatment plant.

2.12.2 Description of Selected Remedy The portion of Alternative 3 regarding installation of wells and piping was undertaken under the authority of the 1998 Interim ROD. Thus, the selected remedy in this ROD is

WDC020930004.ZIP . ' • ' ' 2-24

2-DECISION SUMMARY

continuation of the site-wide groundwater extiaction and freatment, the long-term groundwater monitoring program, and the land use confrols.

The effectiveness of the remedial action will be evaluated in accordance with a long-term groundwater monitoring program. This groundwater monitoring program has been developed by the Navy and awaits review and approval by EPA and WVDEP in accordance with this ROD. The plan shall include periodic groundwater quality and water-level monitoring to assess the degree of contaminant containment and reduction. A review of the remedial action will be conducted every 5 years to evaluate whether the RAOs are being met.

Land Use Control (LUC) Implementation

Institutional contiols will be implemented for Site 10 groundwater to meet the following LUC Objectives:

• Ensure no extiaction of groundwater from Site 10 except for purposes of tiansport to Site 1 for tieatinent (including no exfraction of groundwater for use as drinking water) in the resfricted area shown on Figure 2-7 until the RAOs for OU5 are met and risks from groundwater use are shown to be reduced to acceptable levels.

• Ensure adequate protection to minimize potentially adverse health and environmental effects of work or development in the resfricted area.

• Ensure adequate protection to maintain the integrity of any current or future remedial equipment or remedial monitoring operation in the restiicted area.

The Navy is responsible for implementing, inspecting, reporting, and enforcing the LUC Objectives in accordance with a LUC Remedial Design. The LUC Remedial Design will be developed during the design phase, submitted to EPA and WVDEP within 180 days of signature of this ROD, and will be subject to review and approval by the EPA and WVDEP.

In the event that any LUC Remedial Design implementing action fails or any LUC objective is not met, the Navy will ensure that appropriate actions are taken to reestablish the action and ensure compliance with the LUC Objectives. The Navy may initiate legal action against a third party to compel action and/or to recover the costs for remedying any LUC violation.

Institutional contiols wiU be maintained until the RAOs for OU 5 are met and the concentiation of hazardous substances in the groundwater are at such levels to allow for unrestiicted use and exposure.

2.12.3 Summary of Estimated Remedy Costs The detailed breakdown of costs associated with this remedy is presented in Table 2-7. The information provided in the cost estimate is based on the best available information regarding the anticipated scope of the remedial alternative. Changes in the cost elements are likely to occur as a result of new information and data collected during the engineering design of the remedial altemative. Changes may be documented in the form of a memorandum in the Adminisfrative Record file, an Explanation of Significant Differences (ESD), or a ROD amendment, depending upon the significance of tiie change. The cost

WDC020930004.ZIP 2-25

2-DECISION SUMMARY

estimate provided in Table 2-7 is an order-of-magnitude engineering cost estimate that is expected to be within +50 to -30 percent of the actual project cost.

Expenditures that occur over a time period are analyzed using present worth, which discounts all future costs to a common base year. Present-worth analysis allows the cost of remedial action alternatives to be compared on the basis of a single figure representing the amount of money that, if invested in the base year and disbursed as needed, would be sufficient to cover all costs throughout the life of the remedial project. Assumptions associated with the present-worth calculations include a discount rate of 4.2 percent (OMB Circular No. A-94, Appendix C, Revised January 2000), cost estimates in the plarming years in constant dollars, and a period of performance of 30 years.

2.12.4 Expected Outcomes of Selected Remedy The purpose of the response action is to contiol risks posed by direct contact with contaminated groundwater, minimize the migration of contaminated groundwater, and document the change in the contamination level of the groundwater at Site 10 over time. The results of the baseline HHRA for potential future groundwater users at Site 10 indicate tiiat, at the existing contamination levels, an unacceptable risk exists for the most likely water supply (in other words, exposure to contaminated bedrock groundwater as the water supply). For this scenario, the cancer-risk is within the acceptable EPA risk range, but the HI for the child resident exceeds 1. Furthermore, unacceptable cancer and non-cancer risk values were calculated for both the adult and child resident under the reasonable maximum exposure scenario (in otiier words, exposure to contaminated alluvial groundwater as the water supply). This risk is due primarily to TCE, but other VOCs contribute to the unacceptable risk values.

Groundwater VOC COPC concentiations above their respective MCLs are expected to be addressed as a result of this final remedy. Upon completion of the remedy, projected to be 30 years in duration, it is anticipated that the aquifers at Site 10 will be restored to beneficial use as a potable residential water supply and that restiicted access will no longer be necessary.

2.13 Statutory Determination Remedial actions must meet the following statutory requfrements of CERCLA Section 121:

1. Protection of human health and the environment •

2. Compliance with ARARs (or justification of a waiver)

3. Cost effectiveness

4. Utilization of permanent solutions and altemative tieatnjent or resource recovery technologies to the maximum extent practicable

5. Preference for tieatment that reduces the toxicity, mobility, or volume as a principal element, or explanation as to why this preference is not satisfied

A discussion of how Altemative 3 satisfies each of these statutory requirements is provided in the following subsections.

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2-DECISION SUMMARY

2.13.1 Protection of Human Health and the Environment The selected remedy for Site 10 groundwater is protective of human health and the environment through tieatment of contaminated groundwater and implementation of groundwater use restiictions through appropriate administiative mechanisms until the RAOs are achieved. These components of the selected remedy will eliminate the pathways of potential exposure to contaminated groundwater and ensure that COPC contaminant levels are reduced below the MCLs prior to unrestricted use of the groundwater. In addition, short-term risks associated with exposure to contaminated groundwater during groundwater monitoring and analysis wiU be minimized through safe work practices and the use of personal protective equipment.

2.13.2 Compliance y/ith ARARs The selected remedy will be implemented in compliance with Federal and State requirements that are legally applicable or relevant and appropriate to the remedial action whether chemical, action, or location specific, where possible. The ARARs identified for Site 10 groundwater are summarized in Table 2-8, which includes ARARs for this final remedy as weU as the interim remedy expansion undertaken in 2003.

2.13.3 Cost Effectiveness The selected remedy is the most cost effective altemative because it provides the greatest level of remediation for the lowest constiuction costs, primarily because it takes advantage of using the Site 1 freatment plant. Although Altemative 4 has the same level of protectiveness as Altemative 3, the costs for implementation are much higher because Altemative 4 requires the constiuction, operation, and maintenance of a new tieatment facility at Site 10.

Altemative 3 provides the highest combined level of long-term effectiveness and permanence; reduction in toxicity, mobility, and volume of contaminants through tieatment; and short-term effectiveness.

2.13.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent Practicable The selected remedy represents the maximum to which permanent solutions and altemative freatment technologies can be utilized in a practicable manner for groundwater at Site 10. Of the alternatives that are protective of human health and the environment and comply with ARARs, Altemative 3 provides the best balance of tiade-offs in terms of the balancing criteria established in the NCP, while also considering the statutory preference for tieatment as a principal element and bias against off-site freatment and disposal, and considering State and community acceptance.

The selected remedy also satisfies the criteria for long-term effectiveness by preventing further migration of contaminated groundwater and by reducing VOC contaminant levels.

2.13.5 Preference for Treatment as a Principal Element By utilizing groundwater tieatment as a significant component of the selected remedy, the statutory preference for remedies that employ tieatment as a principal element is satisfied.

WDC0209300W.ZIP 2-27


2.13.6 Five-Year Review Requirements In accordance with Section 121(c) of CERCLA and tiie NCP at 40 CFR § 300.430(f)(5)(iii)(C), because the selected remedy will result in hazardous substances, pollutants, or contaminants remaining on-site above levels that allow for unlimited use and unrestiicted access, a statutory review will be conducted within 5 years after initiation of the remedial action to ensure that the remedy is, or will be, protective of human health and the environment.

2.14 Documentation of Significant Changes The Proposed Plan for ABL Site 10 groundwater was presented for public comment on January 30, 2002. The Proposed Plan recommended Altemative 3, site-wide groundwater exfraction and discharge to the Site 1 tieatment plant, as the Preferred Altemative for Site 10 groundwater. Written comments were received during the public comment period; verbal comments were submitted and addressed during the Public Meeting on February 13, 2002. The Navy, EPA, and WVDEP reviewed aU comments and determined that no significant • changes to the proposed altemative, as originally identified in the Proposed Plan, were necessary or appropriate, except for undertaking the constiuction necessary and initiation of site-wide groundwater extiaction and tieatment under the authority of the Interim ROD.

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2-DECISION SUMMARY

TABLE 2-1 Summary of Chemicals of Potential Concem for Site 10 Groundwater: Future Residential Scenario Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Exposure Point Chemical of

Potential Concern

Groundwater - Alluvial 1,2-Dichloroethene (total)

Methylene Chloride

Tetrachloroethene

Trichloroethene

Arsenic

Manganese

Groundwater - Bedrock 1,1-Dichloroethene

1,2-Dichloroethene (total)

Methylene Chloride.

Tetrachloroethene

• Trichloroethene

Arsenic

Manganese-

WDC020930004.ZIP 2-29

TABLE 2-2 Selection of Exposure Pathways for Site 10 Groundwater Site 10 Groundwater Record of Decision Allegany.Ballistics Laboratory

Scenario Exposure Exposure Receptor Timeframe Medium Medium Point Population

Receptor Exposure On-Site/ Types of Age Route Off-Site Analysis

Rationale for Selecting or Exclusion of Exposure Pathway

Current Groundwater Groundwater Tap Water Industrial Worker

Adult Dermal On-Site Qualitative Absorption

Ingestion On-Site Qualitative

Inhalation On-Site Qualitative

Pathway incomplete - groundwater not currently used on site as a water supply and alternative water supply is available.



Future Groundwater Groundwater Alluvial Aquifer -Tap Water

Resident* Adult Ingestion On-Site Quantitative

Child Dermal On-Site Absorption

Quantitative

Ingestion On-Site Quantitative

Although unlikely, alluvial groundwater could be used as a potable water. supply in the future; therefore, it was evaluated as a reasonable maximum exposure scenario.

Although unlikely, alluvial groundwater could be used as a potable water supply in the future; therefore, it was-evaluated as a reasonable maximum exposure scenario.

Although unlikely, alluvial groundwater could be used as a potable water supply in the future; therefore, it was evaluated as a reasonable maximum exposure scenario.

WDC020930004.ZIP

TABLE 2-2 Selection of Exposure Pathways for Site 10 Groundwater Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Scenario Timeframe Medium

Exposure Exposure Receptor . Receptor Exposure On-Site/ Types of Medium Point' Population Age Route Off-Site Analysis


Future (cont.)

Adult/Child

Bedrock Resident* Adult Aquifer -Tap Water

Child

Dermal On-Site Quantitative Absorption



Dermal On-Site Quantitative Absorption


Adult/Child Dermal On-Site Quantitative Absorption


Although unlikely, alluvial groundwater could be used as a potable water supply in the future; therefore, it was evaluated as a reasonable maximum exposure scenario.

Although unlikely, alluvial groundwater could be used as a potable water supply in the future; therefore, it was • evaluated as a reasonable maximum exposure scenario.

Although unlikely, bedrock groundwater was evaluated as the most likely exposure scenario.

Although unlikely,- bedrock groundwater was evaluated as the most likely exposure scenario.


Although unlikely, bedrock groundv/ater was evaluated as the most likely exposure scenario.


WDC020930004.ZIP

TABLE 2-2 .Selection of Exposure Pathways for Site 10 Groundwater Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Scenario Timeframe Medium

Exposure Exposure Receptor Receptor Exposure On-Site/ Types of Medium Point Population Age Route Off-Site Analysis


Future (cont)

Air Alluvial Aquifer -Water Vapors at Showerhead

Resident Adult Inhalation On-Site Quantitative

Child Inhalation On-Site None

Bedrock Resident Adult Inhalation On-Site Quantitative Aquifer-Water Vapors at Shower- Child Inhalation On-Site None head

Although unlikely, alluvial groundwater could be used as a potable water

• supply in the future; therefore, it was evaluated as a reasonable maximum exposure scenario.

Pathway incomplete - children are assumed to bath, not to shower.


Pathway incomplete - children are assumed to bath, not to shower

Note: 'Noncarcinogenic hazard was evaluated separately for adult and child receptors, combined lifetime carcinogenic risk was evaluated on an age-adjusted basis for the residential scenario.

WDC0209300O4.ZIP

TABLE 2-3 Exposure Factors for Site 10 Groundwater Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Future Child Resident Future Adult Resident

General Receptor Factors

Body weight (kg) 15 70

Inhalation rate (m^/hr) 0.8 0.83

Inhalation rate (m^/day) 15 20 .

Groundwater Exposure Factors

Ingestion Rate (liters/day) 1 . 2

Skin surface in contact while 7,000 20,000 bathing/showering (cm^)

Time bathing or showering (hrs) 0.33 0.2

Exposure frequency (days/year) 350 350

Exposure Duration (years) 6 .30

Inhalation rate (m^/hr) NA 0.83

NA = Not Applicable based upon the assumption that children bathe and do not shower.

WDC020930004.ZIP

TABLE 2-4 Toxicity Information for Chemicals of Potential Concem Site 10 Groundwater Record of Decision All6gany Ballistics Laboratory

Methylene Chemical Name 1,1-DCE 1,2-DCE (total) Chloride PCE

Manganese Manganese TCE Arsenic (food) (water)

Subchronic Oral RfD (mg/kg-day)

Subchronic Oral RfD Source

Chronic Oral RfD (mg/kg-day)

Chronic Oral RfD Source

Subchronic Inhalation RfD (mg/kg-day)

Subchronic Inhalation RfD Source

Chronic Inhalation RfD (mg/kg-day)

Chronic Inhalation RfD Source

Weight-of-Evidence Class

Weight-of-Evidence Source

Oral SF (kg-day/mg)

Oral SF Source

9.00E-03

H

9.00E-03

1

N/A

N/A

C

.1

6.00E-01

1

9.00E-03

H

9.00E-03

H .

N/A

N/A

D

DW

N/A

6.00E-02

H

6.00E-02

1

8.57E-01

H,C1

.8.57E-01.

H,C2

B2

1

7.50E-03

1

1.00E-01

H

1.00E-02

1

N/A

N/A

C-B2

W

5.20E-02

ECAO

N/A

6.00E-03

P3

N/A

N/A

B2

• W

1.10E-02

W

3.00E-04

H

3.00E-04

1 .

N/A

N/A

A

1

1.50E-t-00

1

1.40E-01

1.40E-01

1.14E-04

H,C1

1.43E-05

,C1

5.00E-03

2.40E-02

RI

1.14E-04

H,C1

1.43E-05

l,C1

N/A N/A

WDC020930004.ZIP

TABLE 2-4 Toxicity Information for Chemicals of Potential Concem Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Chemical Name Methylene

1,1-DCE 1,2-DCE (total) Chloride PCE Manganese Manganese

TCE Arsenic (food) (water)

Inhalation SF 1.75E-01 (kg-day/mg)

Inhalation SF Source l,C3 N/A •

1.65E-03

l,C3

2.00E-03

NCEA

6.00E-03 1.51E+01

NCEA l,C3 N/A N/A

Sources: A = Special Report on Ingested Inorganic Arsenic, July 1988, EPA/625/3-87/013.

DW = Drinking Water Regulations and Health Advisories, February 1996.

I CEA = NCEA Regional Support provisional value, USEPA.

H = Health Effects Assessment Summary Tables (HEAST), USEPA, March 31, 1994.

I = Integrated Risk Information System (IRIS), accessed online from the National Library of Medicine, August 1994.

W = Withdrawn from IRIS. Value listed jn HEAST 1991 used.

ECAO = EPA Environmental Criteria and Assessment Office

Rl = Region III Guidance frorii Dawn loven, EPA Toxicologist

P3 = Provisional RfD: Memo from Joan Dollarhide, ECAO, April 1992.

Cl = Calculated from the subchronic inhalation reference concentration.

C3 = Calculated from the unit risk.

Notes:

Cancer Classifications:

A = Known human carcinogenic

B1 or B2 = Probable human carcinogen

C = Possible human carcinogen ,

D = Not know to be a human carcinogen

RfD = Noncancer reference dose -

SF = Cancer slope factor

WDC020930004.ZIP

TABLE 2-5 HHRA Summary by Receptor for Site 10 Groundwater Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Child and Adult

Cancer

Future Resident

Child

Non-cancer

Adult

Non-cancer

Reasonable Maximum Scenario - Alluvial Aquifer

Inhalation

Ingestion

Dermal

Total

Inhalation

Ingestion

Demnal

Total

2.7E-05

9.6E-05

1.2E-05

1.4E-04

Most Likely Scenario

1.3E-05

6.6E-05

4.1 E-06

8E-05

N/A

3.0E+00

1.2E-K00

4

- Bedrock Aquifer

N/A

8.3E-01

2.3E-01

1.1

1.9E-H00

1.3E+00

N/A

3

3.3E-01

3.6E-01

N/A

7E-01

Notes:

The groundwater cancer risk for inhalation is calculated for an adult, for ingestion it is calculated for combined child and adult (age-adjusted), and for demnal is calculated for a child.

WDC020930004.ZIP

TABLE 2-6 (Comparative Analysis of Alternatives Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Criteria

Alternative 1

No Action

Alternative 3 Sitewidie Groundwater

Extraction and Discharge to the Site 1

Treatment Plant

Alternative 4 Sitewide Groundwater

Extraction, Air Stripping, and

Discharge to the Storm Sewer

Alternative 8 Focused Groundwater


Discharge to the Stonm Sewer



Treatment Plant

Overall Protectiveness

Human Health Protection

Groundwater Ingestion for Potential Current Users

Groundwater Ingestion for Potential Future Users

Environmental Protection

Alternate water supply provides protection against potential risk from groundwater ingestion.

No reduction in risk. Increases risk to new users as plume moves to uncontaminated areas.

No reduction in risk. Increases potential risk as plume moves to uncontaminated areas.


Plume migration controlled by pumping. Groundwater use restriction provides protection against risk from groundwater ingestion.until RAOs are met

Contaminant concentrations reduced by extraction and treatment. Migration of contaminated groundwater is controlled by pumping.


Plume migration controlled by pumping. Groundwater use restriction provides protection against risk from groundwater ingestion until RAOs are met.

Contaminant concentrations reduced by extraction and treatment. Migration of contaminated groundwater is controlled by pumping.


Only plume "hot spot" controlled by pumping. Groundwater use restriction provides protection against risk from groundwater ingestion until RAOs are met, but portion of plume continues to move into areas that are not contaminated.

Highest contaminant concentrations reduced by extraction and treatment, but portion of plume continues to move into areas that are not contaminated.


Only plume "hot spot" controlled by pumping. Groundwater use restriction provides protection against risk from groundwater ingestion until RAOs are met, but portion of plume continues to move into areas that are not contaminated.

Highest contaminant concentrations reduced by extraction and treatment, but portion of plume continues to move into areas that are not contaminated.

WDC020930004.ZIP

TABLE 2-6 Comparative Analysis of Alternatives Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Criteria

Alternative 1

No Action



Treatment Plant









Treatment Plant

Compliance with ARARs

Chemical Specific ARARs

Location Specific ARARs

Action-Specific ARARs

Other Criteria and Guidance

Contaminant concentrations will likely exceed MCLs for much longer than 30 years.

No location-specific ARARs.

No action-specific ARARs.

Does not meet the requirehientsof the . State of WV Groundwater Protection Act

Groundwater concentrations will likely meet MCLs within 30 years.

Location-specific ARARs for Site 1 treatment plant addressed in Site 1 groundwater ROD.

Will meet State of WV Groundwater Protection Act requirements and discharge requirements for Site 1 Treatment Plant.

Alternate water supply and groundwater use restriction protect against groundwater

• ingestion.

Groundwater concentrations will likely meet MCLs within 30 years.


Will meet State of WV Groundwater Protection Act requirements and discharge requirements for Site 1 Treatment Plant.

Alternate water supply and groundwater use restriction protect against groundwater . ingestion.

Groundwater concentrations will likely meet MCLs within 30 years, but will require monitored natural attenuation for potion of plume outside "hot spot."


Will meet StatejofWV Groundwater Protection Act requirements and . discharge.requirements for Site 1 Treatment Plant

Alternate water supply and groundwater use restriction protect against groundwater ingestion.

Groundwater concentrations will likely meet MCLs within 30 years, but will require monitored natural attenuation for potion of plume outside "hot spot"

Location-specific ARARs for Site 1 treatment plant addressed in Site 1 groundwater ROD.

Will meet State of WV Groundwater Protection Act requirements and discharge requirements for Site 1 Treatment Plant

Altemate water supply and groundwater use restriction protect against groundwater ingestion.

WDC020930004.ZIP


Criteria

Alternative 1

No Action



Treatment Plant

Alternative 4 Sitewide Groundwater.








Treatment Plant

Long-term Effectiveness and Permanence

Magnitude of Residual Risk

Groundwater Ingestion for Potential Current Users

Groundwater Ingestion for Potential Future Users

Adequacy and Reliability of Controls

Alternate water supply and groundwater use restriction provides protection against potential risk from groundwater ingestion.

No reduction in risk. Increases potential risk to new users as plume moves to. uncontaminated areas.

No controls over contamination; therefore, no reliability.

Alternate water supply and groundwater use restriction provides protection against potential risk from groundwater ingestion;

Remedy will meet RAOs, so residual risk acceptable for future use. Remedy is effective and permanent.

Site-wide groundwater extraction provides the most adequate and reliable control.


Remedy will meet RAOs, so residual risk acceptable for future use. Remedy is effective and permanent.

Site-wide groundwater extraction provides the most adequate and reliable control.

Altemate water supply and groundwater use restriction provides protection against potential risk from groundwater ingestion.

Remedy will meet RAOs, so residual risk acceptable for future use. Remedy is effective and permanent, but . possibly requires a longer time period.

Focused grou ndwater extraction is reliable and adequate for the most contaminated portion of the aquifer. Natural attenuation may eventually reduce contaminant concentrations in the remainder of the plume, but would have to be demonstrated.


Remedy will meet RAOs, so residual risk acceptable for future use. Remedy is effective and permanent, but possibly requires a longer time period.

Focused groundwater extraction is reliable and adequate for the most contaminated portion of the aquifer. Natural attenuation may eventually reduce contaminant concentrations in the remainder ofthe plume, but would tiave to be demonstrated.

WDC020930004.ZIP


Criteria

Alternative 1

No Action



Treatment Plant









Treatment Plant

Reduction of Toxicity, Mobility, or Volume Through Treatment

Treatment Process, None Used

Amount Destroyed or None Treated

Reduction of Toxicity, None Mobility or Volume

Irreversible Treatment None

Type and Quantity of Residues Remaining after Treatment

Contaminated groundwater remains indefinitely.

Treatment at the Site 1 treatment plant using air stripping.

Greater than 95% of VOCs by air stripping.

Highest level in reduction of toxicity, mobility, and volume of contamination by containing and removing largest area of plume.

Groundwater extraction and treatment via air stripping are irreversible.

Treated groundwater. meets discharge limits. Contaminated sludge from filter press requires disposal as hazardous waste.

Treatment at a newly constructed Site 10 treatment plant using air stripping.


Highest level in reduction of toxicity, mobility, and volume of contamination by containing and removing largest area of plume.


Treated groundwater meets discharge limits.

Treatment at a newly constructed Site 10 treatment plant using air stripping. .


Toxicity, mobility, and volume of "hot spot-portion of plume reduced through extraction and treatment, but a portion ofthe plume remains mobile and relies on natural attenuation for reduction in contaminant toxicity and volume.


Treated groundwater meets discharge limits.

Treatment at the Site 1 treatment plant using air stripping.


Toxicity, mobility, and volume of "hot spot" portion of plume reduced through extraction and treatment, but a portion of the plume remains mobile and relies on natural attenuation for reduction in contaminant toxicity and volume.


Treated groundwater meets discharge limits. Contaminated sludge from filter press requires disposal as hazardous waste.

WDC020930004.ZIP


Criteria

Alternative 1

No Action



Treatment Plant









Treatment Plant

Short-Term Effectiveness

Community Protection

Worker Protection

Environmental Impacts

No action results in a continued potential risk to users of contaminated groundwater.

No short-term risk to workers has been identified.

Cohtarhinated groundwater continues to move into areas that are not contaminated.


Protection required against contaminated groundwater during discharge pipe installation.

Contaminant plume reduction over time, air stripping may impact air quality and produce odors.



Contaminant plume reduction over time, air stripping may impact air quality and produce odors.

Only plume "hot spot" controlled by pumping. Groundwater use restriction provides protection against risk from groundwater ingestion until RAOs are met, but portion of plume continues to move into areas that are not contaminated,


"Hot spot" portion of plume reduced over time, air stripping may impact air quality and produce odors; portion of plume continues to move into areas that are not contaminated.

Only plume "hot spot" controlled by pumping. Groundwater use restriction provides protection against risk ifrom groundwater ingestion until RAOs are met, but portion of plume continues to move into areas that are not contaminated.


"Hot spot" portion of plume reduced over time, air stripping may impact air quality and produce odors; portion of plume continues to move into areas that are not contaminated.

WDC020930004.ZIP


Alternative 1 -





Discharge to the



Discharge to the



Criteria

Time Until Action is Complete

No Action

Not applicable

Treatment Plant

Groundwater remedial action complete in 30 years.

Storm Sewer


Storm Sewer


Treatment Plant


Implementability

Ability to Construct and Operate

Not applicable

Ease of Doing More Action if Needed

Would require ROD amendment in future.

Ability to Monitor Effectiveness

Ability to Obtain Approvals and Coordinate with Other Agencies

. No monitoring. Failure to detect contamination means potential impacts from contaminated groundwater over time.

No approval necessary

Existence of interim system makes modification to add additional wells straightforward.

Additional extraction wells could be added easily if necessary; however, increased flow may require treatment system upgrades.

Extraction and treatment system easily monitored to determine effectiveness.

Demonstrate compliance with air emissions standards and effluent discharge requirements.

More extensive than Alternative 3, modification would require construction of new treatment facility.



Demonstrate compliance with air emissions, standards and effluent discharge requirements.

More extensive than Alternative 3, modification would require construction of new treatment facility, but would use existing extraction wells.




This is the interim remedial action; therefore, no modification would be required.

Additional extraction wells could be added easily if necessary; however, increased flow may require treatment system.upgrades.



WDC020930004.ZIP


Criteria

Availability of Equipment, Specialists, and Materials

Availability of Technologies

Alternative 1 -

No Action

Not applicable

Not applicable .



Treatment Plant

No unique equipment or materials required;

.: personnel to operate treatment plant readily

. available.

Utilizes existing Site 1 treatment plant.

Alternative 4 ^ Sitewide Groundwater



No unique equipment or materials required; personnel to operate treatment plant readily available.

Air stripper systems are well developed and commercially available.

Alternative 8 Focused Groundwater'




Air stripper systems are well developed and commercially available.



Treatment Plant


Utilizes existing Site 1 treatment plant.

Cosf

Capital Cost

Annual O&M Cost

Long-term Monitoring Cost

Present Worth Cost

State Acceptance

Community Acceptance

$0

$0

$0

$0

Not Acceptable. Not protective of human

health or the environment. .

Not acceptable.

$ 0 •

$1,580,000

$950,000

$2,530,000

Acceptable

Acceptable

$470,000

$3,510,000

$950,000

$4,900,000

Acceptable

Acceptable

$340,000

$'1,310,000

$950,000

$2,600,000

Acceptable

Acceptable

$0

$1,350,000

$950,000

$2,300,000

Acceptable

Acceptable

WDC020930004.ZIP

TABLE 2-7 Summary of Costs for the Selected Remedy Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Annual Operation and Maintenance Costs for Alternative 3

Description

1. Long-term Monitoring

2. Treatment Plant Operation and Maintenance

Total Annual O&M Costs

Quantity

30

30

Unit

Year

Year

Unit Cost

$54,000

$90,000

$144,000

WDC020930004.ZIP

TABLE 2-7 (CONTINUED) Summary of Costs for the Selected Remedy Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Year Capital Annual O&M

Cost Cost

Summary o f Present Worth Analysis

0

1

4

3

4

5

6

7

8

9

10

11

12

13

14

15

. 16

17

18

19

20

21

22

23

24

25

26

27

$0 $144,000

$144,000

• $144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

• $144,000

$144,000

$144,000

$144,000

$144,iD00

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

Total Cost

$144,000

$144,000

,$144,000

$144,000

$144,000

$144,000

$144,000

. $144,000

$144,000

$,144,000

$144,000

$144,000

$144,000

. $144,000

$144,000

$144,000

$144,000

$144,000 •

. $144,000

$144,000

$144,000

. $144,000

$144,000

$144,000

$144,000

$144,000

$144,000

$144,000

Discount Factor (4.2%)

1.000

0.960

0.921

0.884

0.848

0.814

0.781

0.750

0.720

0.691

0.663

0.636

. 0.610

0.586

0.562

0.539

•0.518

0.497 .

0.477

0.458

0.439

0.421

0.404

0:388

0.373

0.358

0.343

0.329

Present Worth

$144,000

$138,196

$132,626

$127,280

$122,149

$117,226

$112,501

$107,966

$103,615

$99,438

$95,430

$91,584

$87,892

. $84,349

$80,950

•. $77;687

$74,555

$71,550

$68,666

$65,899

$63,242

$60,693

$58,247

$55,899

$53,646

$51,484

$49,409

$47,417

WDC02093O0O4.ZIP

TABLE 2-7 (CONTINUED) Summary of Costs for the Selected Remedy Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Year

28

29

Totals

Capital Cost

$370,000

Annual O&M Cost

$144,000

$144,000

$4,320,000

Total Cost

$144,000

$144,000

$4,690,000

Discount Factor (4.2%)

0.316

0.303

Total Present Worth Cost

Present Worth

$45,506

$43,672

$2,532,774

$2,532,774

Notes:

*Unit costs are for illustration only and should not be used for cost estimating purposes.

Capital cost estimates are not discounted because the system modification work will be performed in the first year. O&M costs are reported as present worth estimates given a 4.2% discount rate for a 30 year duration. Cpst estimates are within - 50 to -30% accuracy expectation.

WDC020930004.ZIP

TABLE 2-8 Description of ARARs for the Selected Remedy Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory

Authority Requirement Regulation Status. Requirement Synopsis

Chemical Specific

Federal Regulatory Requirement

State Regulatory Requirement

Clean Water Act

Groundwater Protection A c t : •

40 CFR 121

40 CFR 403

46 CSR 12.3.1 thru 12.3.3

Relevant and Appropriate

Applicable

Applicable

Contaminated groundwater will be cleaned up to Federal Safe Drinking Water Maximum Contaminant Levels (MCLs).

Pretreatment standards to control the introduction of pollutants.

Standards for purity and quality for groundwater in the state.

Location Specific ARARS


Endangered Species Act of 1978

Executive Order .11988, Protection of Floodplalns

Executive Order 11990, Protection of Wetlands

Criteria for Classification of Solid Waste Disposal Facilities and Practices

50 CFR part 402; - 16 use 1531

40 CFR 6, Appendix A; excluding Secfions 6(a)(2), 6(a)(4), 6(a)(6); 40 CFR 6.302

40 CFR 6, Appendix A

49 CFR 257.3-' 3(c)

Applicable

Potentially Applicable


Requires federal agencies to ensure that any action authorized by an agency is not likely to jeopardize the continued existence of any endangered or threatened species or adversely affect its critical habitat.

Facilities or activities located within the fioodplain must comply with this order. Action taken should avoid effects, minimize potential harm, restore and preserve natural and beneficial values.

These requirements regulate actions that occur in wetlands to minimize the destruction, loss, or degradation of wetlands.

A facility or practice shall not cause nonpoint source pollution of the waters of the U.S. that violates applicable legal substantive requirements implemenfing an areawide or statewide water quality management plan approved by the Administrator under CWA Section 208, as amended.

WDC020930004.ZIP


Authority Requirement Regulation Status Requirement Synopsis

49 CFR 257.3-4 Potentially A facility or practice shall not contaminate an underground and Appendix I . Applicable drinking water source beyond the solid waste boundary or a court-

or state- established alternative.


The Archaeological and 16 USC 469 Historical Preservation Act of 1974.

Rivers and Harbors Act 33 USC 403 of-1890 •


Applicable

Migratory Bird Area 16 USC Section Applicable 703

Requires actions to avoid potential loss or destruction of significant scientific, historical, or archaeological data. Construction on previously undisturbed land would require an archaeological survey of the area.

The North Branch Potomac River is classified as a navigable river. Permits are required for structures or work in oraffecting navigable waters.

Protects almost all species of native birds in the US from unregulated "take" which can include poisoning at hazardous waste sites.

Action Specific ARARs


Clean Air Act

Resource Conservation and Recovery Act

40 CFR 60, Subpart WWW and CC

40 CFR 61

40 CFR 63

Potentially New Source Performance Standard (NSPS): deals with non-Applicable methane organic compounds.

Relevant and Verify that emissions of mercury, vinyl chloride, and benzene do Appropriate not exceed levels expected from sources in compliance with

hazardous air pollution regulation.

Relevant and Emission Standards for new stationary sources. Appropriate

CAA Section 118 Applicable . Control of pollution from Federal Facilities.

40 CFR 262.10(a), Applicable 262.11

Waste generators shall determine if that waste is hazardous waste.

WDC020930004.ZIP

TABLE 2-8 "Description of ARARs for the Selected Remedy Site 10 Groundwater Record of Decision Allegany Ballistics Laboratory


40 CFR 262.34 Potentially Generator may accumulate hazardous waste onsite for 90 days or Applicable less or must comply with requirements for operating a storage

facility. Accumulation of hazardous waste onsite for longer than . 9 0 days would subject to the substantive requirements for storage

facilities.

Federal Regulatory Requirement (cont.)

40 CFR 262.171 Potentially thru 173 Applicable

40 CFR 254.111 Potentially Applicable

U.S. Department of Transportation

40 CFR 264.251 (except 251(j), 251(e)(11))

40 CFR 262.34 (a)(1)(i)&(ii)and 40 CFR 260.11

49 CFR 171.2(f)




49 CFR 171.2(g) Potentially Applicable

49 CFR 172.300 Potentially Applicable

Containers of RCRA hazardous waste must be maintained in good condition, compatible with hazardous waste to be stored, and closed during storage except to add or remove waste.

General performance standard requires elimination of need for further maintenance and control; elimination of postclosure escape of hazardous waste, hazardous constituents, leachate, contaminated njn-off, or hazardous waste decomposition products.

Waste put into waste pile subject to land ban regulations.

Hazardous Waste accumulation and handling regulations and applicable references.

No person shall represent that a container or package is safe unless it meets the requirements of 49 USC 1802, et seq. Or represent that a hazardous material is present in a package or motor vehicle if it is not.

No person shall unlawfully alter or deface labels, placards, or descriptions, packages, containers, or motor vehicles use for transportation of hazardous materials.

Each person who offers hazardous material for transportation or each carrier that transports it shall mark each package, container, and vehicle in a manner required.

WDC020930004.ZIP



49 CFR 172.301

49 CFR 172.302

Potentially Each person offering non-bulk hazardous materials for Applicable transportation shall mark the shipping name and identification

numtier and consignee's name and address.

Potentially Hazardous materials for transportation in bulk packages must be Applicable labeled with proper idenfification number, specified in 49 CFR

172:101 table, with required size of print. Packages must also remain marked until cleaned or refilled with material requiring other marking.

State Regulatory Requirements

Groundwater Protection 47 CSR 58-4.3.2 Act

47 CSR 58-4.4.1

47 CSR 58-4.5.2

47 CSR 58-4.7.1 to 4.7.4

47 CSR 58-4.8.1 and 4.8.4

47 CSR 60-5 to 18 and 47 CSR 60-20 to 22

Relevant and . New areas used for storage shall be designed, constructed and Appropriate operated to prevent release of contaminants.

Relevant and Loading and unloading stations including but not limited to drums. Appropriate trucks and railcars shall have spill prevent and control facilities

and procedures as well as secondary containment.

Relevant and New impoundment shall be designated and operated to prevent -Appropriate contamination of groundwater.

Relevant and Pipelines conveying contaminants shall preferentially be installed Appropriate above ground. Ditches conveying contaminants must have

appropriate liners. Pump and related equipment must be installed to prevent or contain any leaks or spills. Drums and containers shall be stored to prevent spills and leaks.

Relevant and Requirements for secondary containment for sumps above ground Appropriate tanks.

Applicable Requirements and procedures governing the installation and development and/or redevelopment and reconditioning of temporary or permanent monitoring wells(s), piezometers(s), recovery well(s), well(s), and boreholes.

WDC020930004.ZIP



Erosion and Sediment Control; Stormwater Management

Water Pollution Control Act

47 CSR 60-19

Code of Maryland Regulations 26.17.01

46 CSR 1-1 thru 1-9

Relevant and Abandonment requirements and procedures for temporary or Appropriate permanent monitoring well(s), piezometers(s), recovery well(s),

well(s), and boreholes.

Relevant and Appropriate

Any land clearing, grading, other earth disturbances require an erosion and sediment control plan.

Relevant and Rules establishing the requirements governing the discharge or Appropriate deposit of sewage, industrial waste and other wastes into the

waters of the state and establishing water quality standards for the water of the state standing or flowing over the surface of the state.

State Regulatory Requirements (cont)

47 CSR 10

Air Pollution Control Act 45 CSR 7-4.2

45 CSR 25-3.2

45 CSR 25-4.3

Applicable Requirements for NPDES

Applicable Allowable mineral acids stack concentration.

. Relevant and Rules governing the prevention and control of air pollution from Appropriate hazardous waste treatment, storage, or disposal facilities.

Relevant and Facility design, construction, maintain, and operate in a manner to Appropriate minimize hazardous waste constituents to the air.

WDC020930004.ZIP

File Path: v:\18ol8\abl\f1gures\slte10_well8.apr

LEGEND • CERCLA Sites

/ V Roads / V Railroads A ^ Water Bodies

Figure 2-1 Facility Location

Allegany Ballistics Laboratory

4000 Feet

CH2MHILL

File Path: v:\18g)s\ab(Uisure8\sits10_u«ns.apr

9 Hybrid Monitoring Wells LEGEND • Abandoned Wells ~ ••' = A / Roads 8 Alluvial Extraction Wells ^ Fomner Production Wells ^ ^^^^^ ^^^.^^ 9 Bedrock Extraction Wells ^ 3 P'^"* ^ - Developed Area 8 Alluvial Monitoring Wells Q piant 1 - Undeveloped Area 9 Bedrock Monitoring Wells ^ j Buildings

N

300 600 Feet i

Figure 2-2 Site 10 and Associated Features

Allegany Ballistics Laboratory

CH2MHILL

Primary -Source(s) of

Contamination

Primary Release

Mechanism Secondary Source(s)

Secondary Release

Mechanism Pathway

TCE still Spills Soil Infiltration/ Percolation

Groundwater

Exposure Route

Receptor Child

Resident'

Adult

Resident'

Ten-estrial

Biota'

Aquatic

Biota'

Ingestion Inhalation Dermal Contact

•

•

• •

' Future scenario; current scenario is not applicable ' Cun-ent and future scenario

Figure 2-3 Site 10 Conceptual Site Model for Contaminated Groundwater Allegany Ballistics Laboratory

FHe Path: v:MBgIs\abl\flgurBs\slte10_weIIs.apr

CH2MHILL

FHe Path: v:\18oIs\abl\figuTBs\sKe10__wBns.apr

CH2MHILL

File Path: v:\1&gts\abl\fIgiires\sFte10_wen8.

LEGEND S Abandoned Wells 9 Hybrid Monitoring Wells

® Alluvial Extraction Wells E l Fonner Production Wells A / \ A ; ° ^ ^ D H-9 Bedrock Extraction Wells Q Plant 1 - Developed Area ' ^ ^^*®'' ^°°'®^ 8 AJluvial Monitoring Wells g g | piant 1 - Undeveloped Area S Bedrock Monitoring Wells [ g ^ Buildings

A N

300 600 Feet

Figure 2-6 Locations of Existing and Proposed

Extraction Wells at Site 10 Allegany Ballistics Laboratory

CH2MHILL

LEGEND

Area of Restricted Groundwater use at Site 10 A Figure 2-7

Area of Restricted Groundwater use at Site 10

Allegany Ballistics Latwratory

CH2MHILL

3 Responsiveness Summary

The selected altemative for Site 10 groundwater is site-wide groundwater extraction and discharge to the Site 1 groundwater treatment plant. Written comments were received during the public comment period, which was held from January 30, 2002 through March 16,2002. A Public Meeting was held on February 13, 2002 to present the Proposed Plan for Site 10 groundwater and address any questions or comments on the Proposed Plan and on the documents in the information repositories. Seventeen people attended the Public Meeting. Several questions were asked and responded to during the meeting. Based on a review of the comments received, the public appears to generally support 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 A summary of the questions addressed during the public meeting is presented below. Paraphrasing or clarifying annotations to the questions and responses are shown in brackets.

1. My general question is if the natural flow of the contaminated water is towards the Potomac River, what would [the contaminated groundwater] do if you didn't do " an)rthing? How long would it take to clear itself up? And would the contamination that goes into Potomac River be significant enough that it would make any difference with the volume of flow that you have in the Potomac?

Navy Response: If contaminated groimdwater is not contained and extracted at Site 10, but instead is allowed to continue to migrate toward the North Branch Potomac River (approximately 2,000 feet from Site 10), at a minimum groundwater contamination would spread into areas that currently are not contaminated, creating a much larger contaminant plumie. While it is not possible to determine how long it would take for the contamination to decline to acceptable levels if no remedial action is taken, the time would be significantly longer than it would take if an active remedial action is undertaken (such as the estimated 30-year duration assumed for pump and treat).

Nor is it possible to determine that if the contaminant plume is allowed to migrate to and enter the North Branch Potomac River, whether the resulting contaminant levels in the river would be detectable and/or pose a potential risk to human health or the environment. However, before the groundwater pump and treat system at Site 1 was . activated in September 1998, contaminated groundwater from the site discharged to the North Branch Potomac River, and contamination attributed to this groundwater was detected in the surface water and sediment of the river. Since the Site 1 pump and treat system has been in operation, contaminated groundwater has been prevented from discharging to the river and contamination in the river attributed to Site 1 groundwater has declined to nearly undetectable levels.

WDC020930004.ZIP 3-1

RESPONSIVENESS SUMMARY

2. At what rate [will the groundwater be extracted]?

Navy Response: Currently, Site 10 groundwater is under an interim remedial action whereby the groundwater "hot spot" at the site was being extracted at an average rate of approximately 30 gallons per minute (gpm). The groundwater computer modeling performed during Phase III Aquifer Testing simulated the five new extraction wells added to the three existing extraction wells. The computer simulations indicated that about another 46 gpm of groundwater would be extracted by the five new wells, for a total of approximately 76 gpm of Site 10 groundwater extracted and treated under the final remedial action. •

The actual rate that groundwater has been extracted using all the wells at Site 10 is approximately 60 gpm. This flow rate will fluctuate based on several factors, including the individual wells' performance, the area of groundwater capture created with all eight wells pumping, treatment plant capacity, and treatment costs.

3. What is the capacity of the treatment plant?

Navy Response: The existing Site 1 groundwater treatment plant has a design capacity of 300 gpm. Currently, the plant is treating an average of 180 to 190 gpm of groundwater combined from Site 1 and Site 10. i

4. If I were living in Bel Air, I would wonder if the Potomac River was capturing all of the contaminated water or if it might be coming slowly over into Bel Air and Pinto.

Navy Response: Since September 1998, the Site 1 groundwater pump and treat system has been capturing contaminated groundwater and preventing its discharge to the North Branch Potomac River. . ;

Before the pump and treat system was activated, the potential for groundwater to migrate under the North Branch Potomac River into Maryland was evaluated. This was done by assessing the groundwater quality across the river from ABL Plant 1 and by comparing water levels in wells across the river with water levels at ABL and in the river itself. What was found was that no volatile organic cornpounds (VOCs), which were the primary chemicals of potential concem (COPCs) at Plant 1, were detected in the wells across the river from Plant' 1. In addition, the water levels measured in the river were lower than those measured in wells on both the Maryland and ABL sides of the river. This indicates that groundwater on both sides of the river moves toward and discharges into the river and that ground-water at ABL does not move underneath the river into Maryland.

5. Your computer simulation showed various colors, like streams of water, or was it contamination or contaminated water?

I Navy Response: The lines shown in the computer simulation represent the tracks of different particles (for example, COPCs) as they move with the groundwater flow. The different colors of these lines represent different depths in the aquifers where these particles are moving. During the coinputer simulations of groundwater extraction, it was important to verify that contamination in both the alluvial and bedrock aquifers would be captured by the eight proposed extraction wells. Therefore, particles were placed at the top of the alluvial aquifer, bottom of the alluvial aquifer, and in the

WDC020930004.ZIP • • • . 3 - 2


bedrock aquifer at various locations throughout Site 10. The computer then simulated pumping from the three existing alluvial wells, the additional alluyial well, and the four bedrock wells in order to ensure that the combined pumping from these eight weUs would capture contamination throughout the alluvial and bedrock aquifers. , .

A summary of questions and comments received via written corresppndence during the public comment period is presented below.

6. [Under normal circumstances, humans are not exposed to the contaminant levels that are used to develop the extremely conservative risk-based criteria.]

Navy Response: The risk-based criteria that are used to establish acceptable constituent levels in environmental media, for both human and ecological exposure, are by design conservative. It is necessary for the risk-based criteria to be conservative because of the uncertainty inherent in the processes by which the criteria are developed. These criteria are developed through laboratory-scale experimentation that can orily approximate on a very small scale how humans, plants, and animals might be exposed to the various chemicals and what kind of affects the exposure may have. These experiments carmot accurately account for every possible exposure scenario or physiological difference from one person, plant, or animal to another that exist in nature. Therefore, in order to mirumize the uncertainty and to maximize the likelihood that the levels are protective of the health of people, plants, and animals, conservative assumptions are used in the risk-based criteria development process.

7. The most cost effective remedial alternative that would provide adequate human protection is Alternative 1, No Action modified to (1) impose restrictions on the use of groundwater through administrative mechanisms and (2) biannual monitoring and testing for TCE contamination levels. [This is because] (1) there is no immediate or long-term danger to human health, with restricted use of the contaminated groundwater, (2) the natural flow or migration of groundwater to the north east and Potomac River with the TCE contamination being naturally and continuously leached from the soil will eventually bring the contamination to acceptable levels; and (3) the volume of water flow in the Potomac is adequate to dilute any TCE contamination to levels acceptable to human and aquaticlife.

Navy Response: It is true that there is no immediate danger to human health because no groundwater at the site is being used as a potable source. However, while it is likely that ABL will remain as an industrial facility for many years, it is not possible to know whether at some time in the future the facility will be closed and the land redeveloped for residential use. If the groundwater contamination is not remediated before then, either there would be a potential danger to a future resident at the site that used groundwater as a potable source or groundwater use restrictions would have to remain in place even after the facility was closed. Neither one of these is an acceptable altemative.

It is possible that, if no action was taken, as the TCE migrated toward the North Branch Potomac River, the concentrations would decline to an acceptable level. However, it is also possible that the concentrations would not decline to an acceptable level. There are numerous factors that determiiie how the TCE concentrations would decline over time (e.g., dilution, dispersion, biological activity, etc.), and there is also an unacceptable level

WDC020930004.ZIP . ' , • . 3 - 3


of uncertainty in quantifying these factors. If the concentrations did riot decline to an acceptable level and no action was taken to prevent the migration of TCE away from Site 10, then an unacceptable level of contamination would be spread over a much larger area than it currentiy is and will be if groundwater extraction is conducted.

It is also possible that the volume of water flow in the North Branch Potomac River is sufficient to dilute TCE contamination originating from Site 10 to acceptable levels for human and aquatic health. However, before groundwater extiaction began at Site 1, groundwater contaminated with VOCs was discharging to the North Branch Potomac River and producing levels in the river that posed potential risks. Because it is not known whether contamination originating at Site 10 would be diluted to acceptable levels in the North Branch Potomac River, it is more protective of human and aquatic health to capture the contamination at the site and prevent its future discharge to the river.

If groundwater extraction is conducted, the treated groundwater should be recirculated through Site 10 [(i.e., re-injected or broadcast applied)].

Navy Response: Recirculation of tieated groundwater is generally a good idea. However, if the tieated groundwater was to be recirculated through Site 10, it would require that a second tieatment facility be installed at Site 10 or that the water, treated at the Site 1 tieatment plant, be piped back to Site 10, which would require installation of several thousand feet of additional piping. Neither approach is cost-effective. In addition, the objective of groundwater extiaction is to lower the water table in order to capture the contaminated groundwater. U the tieated water was recirculated at Site 10, it would likely raise the water table and hinder the ability of the extiaction wells to maintain capture.

In addition, tieated groundwater from Site 10 will be put to beneficial use. Currentiy, treated groundwater is used by the boiler plant, which generates steam for various uses at the facility, including heat for the various buildings. This use reduces the plant's need to extiact uncontaminated groundwater elsewhere at ABL for this purpose.

Why, during the period of time that TCE was used and TCE contaminated water was a Source of drinking water, [weren't] the personnel tha,t worked at Plant 1 [interviewed] or tested for the incidence of cancer or other harmful effects? They [likely] had far greater exposure to TCE than any current or future humans.

Navy Response: Any human health effects associated with prior use of TCE by workers and previous TCE levels in drinking water are not addressed in this ROD. Installations such as ABL are placed on the National Priorities List, and subsequent to this listing, any potential adverse health affects related to the historic activities at ABL are addressed by the Agency for Toxic Substances and Disease Registry (ATSDR) Health ConsultT

WDC020930(X)4.ZIP I . . 3-4

APPENDIX A

Public Meeting Transcript

WDC02093O0O4.ZIP . . ' A-1

1 MEETING

2 * * * * *

3

4 PROPOSED REMEDIAL ACTION PLAN

5 SITE 10

6 GROUNDWATER PRAP

7 * * * * *

8 ' WEDNESDAY, FEBRUARY 13, 2002

9 •5:40p.m. to-6:05p.m.

10

11 Held at:

12 Allegany Ballistics Laboratory

13 • Building 300 Conference Room

14 210 State Route. 956

15 • Rocket Center, West Virginia

16 . * ' * ; * * *

17 • , I '

18

19

.20

21

1 IN ATTENDANCE:

2 Bruce Beach, USEPA

3 Tom Bass, WVDEP

4 Dominic O'Connor, LANTDIV

5 Lou Williams, LANTDIV

6 John Peters, LANTDIV

7 Dave McBride, LANTDIV

8 John Aubert, NAVSEA

9 John Wau'gaman, ATK

10 Steve Hawk,.ATK

11 Brett Doerr,CH2M HILL

12 • Steve Glennie, CH2M HILL ^

13 Hugh J. Felton, Community Member

14 James Habersack, Community Member.

15 Ken Schulze, Community Member

16 Louis Berstien, Community Member

17 Ron Hawk, Community Member

18 Elayne Warren, Community Member

1 9 ' • • .

20 .

21

1 P-R-0-C-E-E-D-I-N-G-S

2 (5:40 p.m.)

3 MR. WILLIAMS: As most of you know,

4 I'm Lou Williams. I'm the Navy Co-Chairman of

5 the Restoration Advisory Board. Tonight we have

6 the public meeting discussing two -- well, one

7 proposed action here on site, and review of the

8 five-year review of "implementation act-ion we put

9 in place. Mr. Brett Dderr of CH2M Hill here will

10 go over those two issues. After that, we will

11 have our standard Restoration Adviso2ryBoard talk

12 about a few options we are'considering doing

13 here. We' have a sign-in sheet. If you are not

14 on our mailing list, please.put down a mailing

15 address where we' can send you correspondence. If

16 you have an e-mail, put that down also, and it

17 will make.it convenient for me to keep you

JS updated.on what's going on.

19 Dr. Betsy Kagey, as you know, is the

20 Community co-chairperson. She couldn't make

I

21 today.'s meeting, but she was here yesterday. She

http://make.it

1 said to proceed on without her. Without further

2 ado, I think Mr. Brett Doerr will kick off the

3 first presentation.

4 MR. DOERR: (Referring to the

5 PowerPoint(tm) presentation): I think most

6 everyone here is -- I've seen you all over the

7 years, and you are familiar with Site 10, which

8 is the former TCE Still down at Building 157, and

9 production wells -- former production wells are

10 down there, PWA and PWC. That site is currently

11 under an interim remedial action where we are

12 doing hot spot, groundwater .extraction and

13 treatment at the treatment plant we have down at

14 Site 1. That has been ongoing since 1999. •

15 Since that time, we have gathered a

16 lot of information about what are we going to do •

17 with the rest of the plume -- the groundwater

.18 contaminant plume that is down there. We are

19 just focusing on the highest areas of

20 contamination of how we are going to address the

21 rest of the plume. We gathered a lot of

1 information over the last several- years and have

2 come up with what we think is the best way to

3 capture all of the groundwater contamination at

4 Site .10 (referring, to Slide 1) .

5. Today's presentation is what the Navy

6 is proposing to do in the final remedial action

7 for all the groundwater contamination at Site 10.

8 Let me start off with saying what the Navy's

9 preferred alternative is (referring to Slide 2).

10 That is sitewide groundwater extraction and

11 sending that water to the Site 1 groundwater

12 treatment plant for treatment. .

13 That differs .from what we are

14 currently doing. As I.said,- currently we are

15 doing hot spot contamination extraction, focusing

16 on just the highest concentration areas of the 1

17- plume. What we propose to do is expand that

18 groundwater extraction to capture the-entire

19 plume.

20 These are the topics I will cover

21 during the course of this presentation (referring

1 to Slide 3): Talk a little about the facility

2 and the background of Site 10, the nature and

3 , extent of contamination that is down there,,

4 previous investigations and activities that have

5 been conducted at Site 10, what the different

6 remedial alternatives that were evaluated were.

7 Again, we state what the preferred alternative

S i s .

9 Then there's some other information

10 about where you can go to find more information

11 and how you can contact the Navy or EPA or West

12 - Virginia if you have any comments or questions.

13 The facility, ABL, is located in the

14 northern part of Mineral County separated from

15 Allegany County', Maryland by the North Branch

16 Potomac River (referring to Slide 4). It's been

17 here since 1943, used primarily for development,

18 production and testing of solid propellants and

19 motors for ammunition, rockets and armaments.

20. . There are two plants.. The big plant,

21 Plant 1, is 1,577 acres and is owned by the Navy'

1 and operated by ATK Tactical Systems. Plant 2 is

2 a 57-acre facility immediately adjacent to Plant

3 1 that's owned and operated exclusively by -ATK. -

4 This just shows -- just kind of gives

5 you a layout of where everything is (referring to

6 Slide 5) . The entire', facility -- Plant 1 and

7 Plant 2 -- and the location of Site 10 is here.

8 The south central portion of the developed •

-9 portion of site --of Plant 1.

10 This site includes the former TCE

11 recovery still which is located at Building 157

12 (referring to Slide 6). They used that to

13 recover the degreasing solvents that they used on

14 the machines and part's., It also -includes former

15 production wells PWA arid PWC. I will show you

16 the relative locations .in a minute.

17 The TCE use arid storage at that

18 building began in about 1960. It didn't last

19 very long. It stopped by the early 1960s. This

20 shows you -- this is an aerial photograph from

21 ' 1962,' I believe (referring to Slide 7). It shows

1 you the relative locations of various features of

2 Site 10. Here is PWC, Former Production Well C,

3 Former Production Well A. There is Building 157

4 and the TCE still was immediately adjacent to

5 that building. The outside of the building,

6 about right there.

7 As we have across most of ABL, at Site

8 10 we have two aquifers (referring to Slide 8):

9 The alluvium, which is primarily silt, clay,

10 sand, unconsolidated material, some gravel; and

11 we have bedrock below the alluvium, which is

12 predominantly shale and bedrock, that is

13 encountered at about 23 feet below the ground

14 surface.

15 . The natural flow -- when I say

16 "natural," I mean in the absence of pumping. If

17 we weren't out there pump ing and we were just

18 letting the groundwater flow on its own, the

19 natural flow in both the bedrock and alluvial

20 aquifers is north/northeast toward the North

21 Branch Potomac River, which is believed to be the

1 ultimate discharge point of the groundwater.

2 In addition to the pumping we are

3 doing out there right now with the groundwater

4 extraction, historical pumping of Wells A and C

5 . is also believed to have altered the groundwater

6 flow direction during the time they were pumping.

7 Over the years, we have done a number

8 of studies, out at Site 10 and found that volatile

9 organic carbons, often referred to as VOCs, are

10 the primary contaminants that we find in the

11 groundwater, both in the bedrock and the alluvium

12 (referring to Slide 9) .' Of the VOCs that we

13 find, TCE, or trichloroethene, is the most common

14 VOC: We find' that in most locations and also at

15 the highest concentrations.

16 We also found, through putting in a

.17 • number of wells, that' the area of contaminated

18 groundwater in both bedrock and the.alluvial

19 aquifers is extended toward the northeast'

2.0 direction, which isn't I too surprising, because

21 that was the direction of natural groundwater

10

1 flow, anyhow.

2 We also found that in the bedrock

3 aquifer, the plume is elongated somewhat toward

4 the south. The reason, we feel, is because

5 historical pumping of Well PWA pulled

'6 contamination toward it. PWA is a bedrock well.

7 In fact, both PWA and PWC are bedrock wells. We

8 feel that in addition to the natural flow

9 carrying contamination off toward the northeast,

10 pumping of PWC and PWA pulled contamination -- in

11 -this case, PWA pulled contamination toward the

12 south. This is a figure showing the approximate

13 area of bur TCE. flow (referring to Slide 10).

14 This boundary corresponds generally with'the

15 Maximum Contaminant Level which is a federal '

16 regulatory level -- MCL is what they call it --

17 . of five ppb, parts per billion, which is the MCL

18 for TCE. This is approximately what our TCE

19 plume looked like before we started pumping out

20 there back-in 1999..

21 Just to orient you, and I have to .

11

1 orient myself first. Building 157 is here

2 (referring to Slide 10). As you can see, the

3 plume is sort of elongated in that northeast -

4 direction.

5 AUDIENCE PARTICIPANT: What scale is

6 that?

7 MR. DOERR: Good question. The le'gend

8 seems to be cut off. This is about.-- this is

9 probably close to 700 or 800 feet (referring to

10 Slide 10). . This is the same kind of figure,

11 except for the 'bedrock aquifer (referring to

12 Slide 11). !

13 As I said-before, here is our. source .

14 area here, what we think is our source area, the

15 former TCE still. The:groundwater natural flow

16 is toward the northeast carrying the plume in

17 this direction, but historical pumping down here

18 at PWA also pulled some of that plume toward PWA.

19 A number of, studies' have been

20. conducted at Site 10 starting in 1987 (referring

21 to Slide 12). In fact, that was the first time.

12

1 in 1987, they were doing an evaluation of all' the

2 plant production well's. -They first encountered

3 contamination in both PWA and PWC.

4 Several years later, that was followed

5 up with the Remedial Investigation, often

6 referred to as the RI. During that RI, Building

7 157 and the former TCE still at that building was

8 identified as the probable source of the TCE

9 found in those two wells. They put some more

10 monitoring .wells in both the alluvial and bedrock

11 aquifers at that time, and they confirmed the

12 presence of TCE in the vicinity of PWA.

13 Based on the findings and

14 recommendations of the Remedial Investigation,

15 Phase II Remedial Investigation was conducted in

16 1994 to gather additional information, the extent

17 of the plume in both the bedrock and the alluvial

18 ^ aquifers, as-well as to determine what the

19 potential risks were to human health, plants, and

20 . animals from potential exposure to the

21 contamination in trie groundwater.

13

1 This is what the risk assessments

2 found (referring to Slide 13). In terms of human

3 healtri risk, there was really no risk to

4 potential on-site workeirs because once the

5 contamination was found in those two wells, they

6 were taken out of service in terms of production

7 wells. There was no water used for riuman

8 consumption on the plant from those two wells any

9 longer.

10 However, if some time in the future,

11 ABL were to become a residential area and

12 somebody were to put a well in and drink water,

13 there would be a risk for those future residents.

14 It is a very conservative risk evaluation fo

15 make, but you riave to be protective of what' may

16 happen to ABL in.the future.

17 . In terms of .potential risk to plants

,18 and animals, there really was not a risk riere

19 because trie groundwater is not utilized by plants

20 and animals.. Certainly not in trie viqinity of

21 our plume'. You know, we don't riave trees where

14

1 their roots extend down into the groundwater. We

2 don't have animals living down in the

3 groundwater, so there really didn't seem to be an

4 ecological risk or a risk to plants and animals

5 . from the groundwater contamination.. The risk was

6 really to potential future residents that could

.7 possibly live there if ABL was converted into a

8 residential area.

9 Following trie Priase II Remedial

10 Investigation in late 1995 and,early 1996, an

11 aquifer test activity was undertaken to determine

12 if groundwater extraction could be. used t.o pull

13 trie groundwater contamination out of Site 10

14 (referring to Slide 14)..

15 At triat time, we de-veloped our first

16 groundwater flow model for Site 10 where we

17 simulate groundwater flow. We go out and measure

18 actual field data, and we take triat information

19 and generated a computer model to simulate

20 groundwater flow and also to-simulate where, if

21 we put extraction wells, in,' might we best pull

15

1 this contamination back out.

2 Based on some of our initial findings

3 with that first model during the Phase I .^quifer

4 Testing, we went back out in late 1996 and .

5 conducted Phase II Aquifer Testing to verify some

6 •of trie assumptions we used in that groundwater

7 model. We also found during this aquifer testing

8 that it seemed like the groundwater extraction

9 ' was going to work well'for our hot spot --we

10 called it the riot spot. It's trie areas of the

11 higriest TCE contamination in the groundwater --

12 but it was not clear whether groundwater

13 extraction would work -well for trie entire plume.

14 Based .on all triat information triat we

15 gatriered from all those studies, a feasibility

16 study was done in 1998; (referring to Slide 15).

17 The purpose of the feasibility study is to

18 determine the feasibility of using -- and

19 evaluate the number'of alternatives - to determine

20 their feasibility in treating the contaminated j. . . . •

21 groundwater we have at Site 10.

16

1 As part of trie development of trie

2 feasibility study, you develop your Remedial

3 , Action-Objectives. In other words, what are you

4 trying to accomplish with your remedy.- Two

5 Remedial Action. Objectives, or RAOs as they are

6 sometimes called, were developed for Site 1.0.

7 That is, prevent or minimize the exposure of

8 potential future residents to the contaminated

9 -groundwater and restore as much of trie aijuifers

10 to beneficial use as is tecrinically and

11 economically feasible.

12 , So based on those findings, based on

13 the evaluation of triose remedies, an interim

14 PRAP, which is the Proposed Remedial Action Plan,

15 and ROD, whicri is Record of Decision, for Site 10

16 groundwater were put in place in 1998 (referring

17 to Slide 16). Triis kind of public meeting was

18 done back, in 1998 to present to trie public trie

19 proposed interim remedy.

20 . . On an interim basis, the preferred

21 alternative was to.go in there, start pumping the

17

1 hot spot to prevent its further migration, and

2 treat it down at the Site 1 groundwater treatment

3, plant while we evaluate other options for _trie

4 remainder of the contaminant plume.

5 The,riot spot was defined as an area of

6 about 100 to 500 parts per billion of TCE..

7 Anything less than that was part of the broader

8 plume whicri was going to be evaluated over time.

9 The interim remedy was to go in there arid pump

10 the area of higrily-concentrated plume and try to

11 reduce trie concentration and prevent its furtrier

12 migration. •

13 Triis talks about the Public Comment

14 Period -- when trie Public Comment Period was

15 rield -- trie public meeting -- and trien when the

16 Record of Decision -was signed June 1998

17 (referring to Slide 1 6 ) . Between June of 1998

18 and February of 1999, - three alluvial extraction

19 wells were installed in trie riot spot of trie

2 0 groundwater plume.

21 Now, the only reason.alluvial

18

1 extraction wells were installed is because, at

2 triat time, there was a belief that if we.pumped

3 the alluvial aquifer, wriicri is wriere most of trie

4 groundwater contamination was found to be, that

5 any contamination in trie bedrock aquifer would be-

6 pulled up into the alluvium.'

7 That assumption was based on the fact

8 that when we.had wells sitting right next to one

9 another wriere one is an alluvial well and one is

10 a bedrock well "-- wrien we measured water levels.

11 in triose wells, we found that water in the deep

12 bedrock wants to come up into the alluvium. So

13 we felt by pumping the alluvial aquifer, that

14 would just- enhance that natural feature arid we'

15 would be able to capture any bedrock groundwater

16 also.

17 ' So in February 1999, triose triree wells

18 were turned ori and began pumping the hot spot

19 contamination to the Site 1 treatment plant- for

20 treatment.

21 Since that time, we have been

19

1 evaluating a lot of data that we riave been

2 collecting to try to determine what is trie best

3 way to capture the rest' of trie -- or to treat trie

4 rest of trie plume that we have out there. We

5 have done that by evaluating monthly water

6 levels. Ever since February pf 1999, we have

7 been collecting water levels on a monthly basis

8 at Site 10-to help us determine riow mucri of trie

9 plume are we actually capturing witri triose triree

10 wells we- riave currently pumping (referring to

11 Slide 17). We have made a guess, based on

12 computer modeling, how much we were going to

13 capture, but the actual- monthly water level

14 measurements allow us to see how much we actually

I

15 are capturing. We -coupled triat witri periodic .' I

16 groundwater sampling to let us know are we

17 ' sririnking that plume down, or is more of it

18 escaping. . . i

19 Evaluation of all that information

2.0 .over trie last few years rias given us two

21 . important findings:' One, we found that triose

20

1 three wells we put in just to do hot. spot

2 remediation were actually capturing a lot more of

3 trie plume than we had originally planned. They -

4 were capturing almost the entire part of the

5 alluvial groundwater plume. This was trie good

'6 news.

.7 We found a little piece of bad news,

8 too, in triat we found triat the water levels that

9 we used to -measure in our well pair --we had an

10 alluvial and a bedrock pair --we used to measure

11 -water levels that indicated the water wanted to

12 come up from the bedrock into trie alluvium. It

13 didn't want to do that anymore. It wanted to. go

14 down into the bedrock, which we didn't want to

15 happen because we didn't riave extraction wells in

16 trie bedrock-. We were planning on our alluvial

17 wells pulling any bedrock contamination up. We

18 were finding triat the water wanted to go down

19 into trie bedrock instead.

2 0 The hypothesis for why that was

21 happening is triat right around trie same time trie

21

1 Site 10 wells were put 'online. Site 1 wells were

2 put online. Remember Site 1 rias 34 extraction

3 wells; it rias 27 alluvial extraction wells and 7

4 bedrock extraction wells. So trie triought was

5 that maybe the pumping that we are doing down at

'6 Site 1 is affecting the water levels at Site 10

7 and causing the water to want to flow down into

8 trie bedrock and trien work'its way toward Site 1.

9 In order to,test triat riypotriesis, we

10 conducted wriat we call Priase III Aquifer Testing.

11 We had two objectives (referring to Slide 18).

12 Remember I said that from all trie data we

13 gatriered, it. looked like triose triree alluvial

14 riot-spot wells were actually capturing most of

15 trie alluvial contamination,' but'we wanted to

16 figure out if we put in one more alluvial

17 extraction well, could, we capture trie rest of the

18 alluvial aquifer plume'.

19 The second thing we wanted to find out

20 was is Site 1 pumping really affecting Site 10

21 and our ability to capture the bedrock ^

22

1 contamination at Site 10.

2 We did this by going out and -- we

3 satisfied triis first objective by going out and

4 defining the portion of the plume that we thought

5 we weren't capturing; the small tip, the

6 northeast tip of trie alluvial plume that we

7 thought we weren't capturing. We went out there

8 and did some testirig to find out exactly how far

9 out that plume went. Trien we did some computer

10 simulations of putting a fourtri alluvial well in

11 until we captured, at least wriat trie computer

12 model sriowed, captured thfe rest of that plume.

13 Trie second triing we did is we did a

14 large scale pumping test where we shut down all

15 of the wells at both Site 10 and Site 1 and let

16 all trie water levels recover over trie course of

17 about five days. Once all of trie water levels

18 riad recovered, we turned on only the bedrock

19 wells at Site 1 and we started measuring water

2 0 - levels at Site 10. So we are pumping, down at

21 Site 1 and we are measuring water levels at Site

23

1 10 to see if there is any response.

2 We took all that information back and

3 we developed a more sophisticated groundwater

4 model triat combined Sites 1 and Site 10. You

5 know, for several years we've riad a groundwater

6 model for Site 1 and we've riad a groundwater

7 model for Site 10. Now that we think there is a

8 hydraulic connectioti between the two,.we wanted

9 to develop a model that could simulate that

10 hydraulic connection, so we developed a unified

11 model that could explore botri Site 1 and Site 10.

12 Triis is riow we sa.tisfled triat first

13 objective I was telling you about about

14 evaluating riow far out, triis nortrieast tip of the

15 plume goes (referring-to Slide 19). We did that

16 by -- we poked all triese little rioles in the

17 ground and took groundwater samples to see wriat

,18 the TCE concentration was. By doing that, we

19 were able to determine that this is -- it's very

20 hard to see, but there' is a line riere.triat goes

i-21 around. Triat r ep resen t s , r e a l l y , trie nortrieast

24

1 extent of this plume.

2 By doing triat, we were able to figure

3 we could put anotrier well in rigrit riere and we

4 should be able to capture the rest of triat plume

5 - in.trie alluvium (referring to Slide 19).

6 Trie data we collected from triat

. 7 long-term -- that big pumping test we did where

8 we pumped' the wells down here at Site 1 and we•

9 read trie water levels riere --we took all that

10 information- and put it back into trie computer

11 model (referring to Slide 20). Then we ran some

12 simulations with a computer model where each one

13 of these lines represents -- you can think of it

14 as if you put a drop of contamination in trie

15 groundwater at any one of triese points, where

16 would it go?

17 We simulated trie triree wells that we

18 currently are pumping. Triese are trie three

19 hot-spot wells triat we are currently pumping

20 (referring to Slide 20). So- we let triem, in the

21 computer model,.we let them keep pumping, but we

25

1 also had our wells down in Site 1 -simulated

2 pumping as they are currently pumping; all the

3 bedrock wells pumping and all 27 alluvial, wells

4 pumping.

5 When you do that, what the computer

6 simulates is that some of the contamination

. 7 escapes. It doesn't make it to the riyer. It's

8 cut off by Site l. While it may seem like there

9 is no problem witri triat, the problem is triat what

10 you have then done is you riave allowed

11 contamination to spread over a large area, ratrier

12 trian being caught all here at Site.10. So the

13 data really did sriow triat Site 1 was affecting

14 our ability to capture'all trie groundwater

15 contamination at Site 10.

16 Now triat he had this unified computer

17 - model' that we had developed, we were then able to

18 start pretending we were pumping from trie

19 bedrock; simulating pumping from trie bedrock at

20 Site 1.0 to see --we tried ail kinds of different

21 scenarios; we tried more alluvial wells, we tried

26

1 more bedrock wells. Wriat we were able to do is

2 actually simulate.

3 Triis a picture of the same computer

4 simulation as the last picture that showed all

5 that escape (referring to Slide 21). Trie

6 difference is we have'now simulated pumping from

7 four bedrock wells at Site 10. So, you see, none

8 of those lines are escaping anymore to get down

9 to Site 1. They are all being caught right here

10 at Site 10. -

11 Again, we went back to the feasibility

12 study triat was done a long time ago. The

13 feasibility study that was used to propose and

14 implement the Interim Remedial Action, whicri is

15 trie hot spot gro-undwater remediation. We went-

16 back to those' alternatives and we reevaluated

17 triem witri trie new information that we riad witri

18 the ultimate objective of reaching a final

19 remedial action for Site 10 groundwater.

20 Here are the different alternatives

21 triat we evaluated (referring to Slide 22). Now,

27

1 you see the numbers don't go 1 through 5. The

2 reason is this is what is called a detailed

3 analysis. There was really a number of - •

4 alternatives that were initially triougrit of, but

5 you eliminate some right off the bat because they

6 are not technically or economically feasible.

7 Trie ones triat are, you trien send triem

8 trirough a detailed analysis where you spend a

9 little more time going througri a more detailed

10 and rigorous evaluation of each one of triose-

11 different alternatives..

12 The first alternative is the No Action

13 Alternative, whicri means we do notriing else. You

14 evaluate triat alternative really as a baseline.

15 You compare everything else to doing nothing. -

16 The other four alternatives are really -- triere-

17 are really two alternatives witri slightly

18 different treatment alternatives. Two of them

19 are sitewide ground water extraction at Site 10.

20 - Trien for eacri one of trie -- for

21 sitewide ground water extraction, we eitrier send

28

1 the water to the Site 1 Treatment Plant, or we

2 will treat it there at Site 10. To do that, we

3 would have to build anotrier groundwater treatment

4 plant there at Site 10.

5 The other two alternatives are

6 sticking with the focused extraction that we are

7 doing right now with just those three wells --

8 not putting anymore in -- and, again, doing the

9 same thing; either treating trie water down at

10 Site 1, or building a new treatment plant at Site

11 10. Then in terms of the rest of the groundwater

12 contamination which is not being captured,

13 monitoring it to see riow far it does spread and

14 riope that it doesn't. Hope that it declines in

15 concentration on its own over time and that

16 nothing is necessary to capiture. Those are the

17 ' alternatives that were evaluated.

18 For demonstration purposes, we made

19 triis table (referring to Slide 23). Triese are

20 eacri of those five alternatives that we just

21 listed. Trien we put a ranking to eacri one of

29

1 them. Here are the objectives of the groundwater

2 treatment and the different alternatives that we

3 had on triat last slide. Here is how they are

4 ranked in terms of satisfying these objectives.

5 Of course, what you fi'nd out is the No Action one

6 doesn't satisfy anything. The only great thing

7 about the No Action was it doesn't cost anytriing,

8 but it doesn'.t meet any of trie otrier clean-up

9 objectives.

10 Trie problem witri trie focused

11 extraction, whicri is wriat is going on right now;

12 the three wells. The problem witri triat is it

13 doesn'.t capture all of trie plume. You- are going

14 to spend a -lot of effort and money tracking triis

15 plume to make sure -it doesn't cause a problem in

16 trie future.

17 Where you have your highest -- where

18 triese objecti-ves are satisfied trie best was

19 Altemative 3, whicri was sitewide groundwater

20 extraction, which is trie figure I sriowed you

21' where we captured all the contamination right at

30

1 Site 10 by doing sitewide groundwater extraction

2 and sending triat water down to Site 1 Treatment

3 Plant to be treated, ratrier trian building a .new

4 treatment plant at Site 10. There is really no.

5 reason to do that. We already have a treatment

6 plant down at Site 1 that can handle some

7 additional groundwater flow. We'll just pipe it

8 down triere and let the Site 1 Treatment Plant

9 treat it'.

10 Triat's trie Navy's preferred

11 altemative (referring to Slide 24). We riave'

12 that foiirtri alluvial extraction well to get the

13. very northeast tip of- the alluvial plume that is

14 not currently being captured. We.convert three

15 of our existing monitoring wells -- our bedrock

16 monitoring wells we have out there. Here are the

17 well numbers (referring to Slide 24). We convert

18 three of triem into extraction wells. We also

19 employed PWC, trie Former Production Well C. We

20 . will make it an extraction well now.

21 • So with those four bedrock extraction

31

1 wells and that fourth alluvial extraction well

2 pumping, we are hoping to get complete capture of

3 that groundwater plume.. We will install a couple

4 of additional bedrock monitoring wells to monitor

5 whether we are meeting our objectives and we'll-

6 make groundwater use restrictions. They are

7 implemented now. We will retain and implement

8 groundwater use restrictions, so groundwater

9 can't be used at Site 10. Triis will prevent

10 further migration of the VOC contamination,

11 treatment at the groundwater treatment plant, and

12 we will do long-term monitoring. That includes

13 montrily water level measurements and periodic

14 groundwater sampling to ensure we are meeting

15 those objectives.

•16 Triis just sriows you wriere triose wells

17 are that we are talking about (referring to Slide

18 25) . Here is- the source area. This is Building

19 157 where the former TCE still was located. Here

20 , is one of the wells we .are going to convert to an

21 extraction well. Here is the second one, trie

32

1 third one, and here is PWC.

2 As you can see, they are oriented in

3 triat natural flow direction triat. the groundwater

- 4 wants to move anyhow, which helps capture the

5 groundwater. I showed you triat fourtri alluvial

6 extraction well that I've got here. The alluvial

7 plume is bigger than the bedrock plume.

8 What this shows -- this is kind of a

9 difficult one to look at, but what triis shows is

10 that computer model simulation again (referring

11 to Slide 26). We are just showing some different

12 features. Here are triose same lines all getting

13 caught by the wells here at Site 10 showing you

14 the capture. What triese lines are, if you can

15 imagine trie water surface riere. If you were to

16 cut trirougri trie aquifer and look at the water

17 surface, triis represents trie sloping water

18 surface.

19 -What you are seeing here, triis feature

20 here, is exactly what you would see if.you look

21 through the side as trie water comes in like this.

33

1 This shows triat you can.capture trie water. The

2 groundwater would move perpendicular to triese

3 lines. You can see it. It would come in and you

4 would capture it here. '

5 Trie' way we would make sure that we

6 were getting that capture is that we put in two

7 crucial monitoring wells in this area so triat if

8. we were getting escape,! triese wells would pick .

9 that up (referring to Slide 26).

10 Again, I just want to go back and sriow

11 you everytriing I've just been talking about in

12 terms of wriere the wells aire. and how triey

13 capture -- again, triis is one triat I sriowed you

14 earlier (referring to Slide 27). Triis is our

15 computer simulation. It's trie three existirig

16 wells triat are currently Out triere pumping. It's

17 the one more -- adding that fourth alluvial

;18 extraction well right triere, and trien our four

19 bedrock extraction wells. Triat simulation-shows

20 that we can keep all the contamination at Site

21 10. None of it escapes to Site 1.

34

1: That's it. That's the preferred

2 alternative. All the information triat I

3 , presented riere in terms of the previous stjidies

4 that were done back starting in 1987 trirougri the

5 most recent Phase'III Aquifer Testing, all that

6 information can be found in the Administrative

7 Record for Allegany Ballistics Laboratory. Triat

8 Administrative Record is kept in two places; one

9 is in .the LaVale Public Library and the other one

10 is in the Fort Ashby Public Library' (referring to

11 Slide 28).

12 This just summarizes the public

13 comment period for this preferred alternative

14 (referring to Slide-29). It started on January

15 30th, and it goes through March 16th. During

16 this period, you can submit questions, comments

17 to trie Na-vy, EPA and West Virginia. Here are the

18 contact names (referring to Slide 29). The

19 addresses, phone numbers and e-mails are on the

20 PRAP documents. In fact, if anybody wants a copy

21 of the PRAP before.you leave, I've got it here.-

35

1 It's a document that basically summarizes

2 everything triat we just talked about. I riave it

3 , riere for anybody who wants to take a copy pf that

4 with them.

5 Please postmark your comments or

6 questions by March 16tri, wriicri is trie last .day of

7 the public comment period. Any comment we

8 receive or any question we receive will be

9 -evaluated, answered, and they actually will go as

10 an attachment to trie Record of Decision. All

11 comments and questions will be considered in

12 making any crianges to what the preferred

13 altemative is.

14 I'd be happy to entertain any

15 questions. If you do have any questions, please,

16 if you could state your name for trie record.

17 MR. FELTON:, My name is Hugh Felton.

18 I'm on trie (Inaudible)-, Public Service District

19 board witri (Inaudible)-water and takes care of

20 sewage at Wiley Ford and (Inaudible.) My general

21 question is.if trie.natural flow of the

I •

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36

1 contaminated water is towards the Potomac River,

2 wriat would it do if you didn't do anything? How

3 long would it take it to clear itself up? And

4 would the contamination.that goes into Potomac

5 River be significant enough that it would make

6 any difference with the volume of flow that you

7 have in trie Potomac?

8 MR. DOERR: That's.a good question.

9 In fact, before trie,Site 1 groundwater wells were

10 put into operation -- Site 1 is right on the-

11 river. Site 10 is 1,000 or so feet, or a couple

12 triousand feet back from trie river.

13 Before the Site 1 groundwater

14 extraction wells were turned on, we found TCE and

15 other volatiles in the river sediment every, time

16 we monitored it. Every time we took samples, we

17 found it in the river! Site 1 has been

18 operational since 1998, and we don't find VOCs in

19 the river anymore. It rias been declining ever

20 since we started pumping triose wells.-

21 At Site 10, you are right.

37

1 Contamination that is triere would spread out over

2 time and may reacri the river. You don't know if

3 it's going to adversely impact the river once it-

4 finally reaches triere or not. However, if you

5 let it go, that means from where it began, which

6 is at Building 157, to the river, now all that

7 area is contaminated. Is it contaminated above a

8 risk level? Possibly.; It's possibly i

-9 contaminated above a level triat would allow it to

10 be used by humans for consumption, or for bathing

11 or for any potable use.

12 MR. FELTON:\ For how long? I

13 MR. DOERR: There is no way to know.

14 Trie life expectancy of I trie Site 1- groundwater

15 extraction wells, the estimated -- it was I

16 estimated in trie feasibility study triat was done

17 for Site 1 -- I triink'a 30-year cleanup period.

18 Triat's actively pulling trie water out of trie

19 ground and trying to get trie contamination out of

20 there. The estimate is that it would-be, at

21 least, 30 years to gett it out of there." So if

38

1 you are not pulling it out at all, you can kind

2 of get an idea of how long it's going to last

3 there.' • . . ' .

4 MR. FELTON: . What rate do you pull it.

5 out?

6 MR DOERR: It varies, i You pick a rate-

7 where you are not -- you want to'balance trie cost

8 of trea!tment versus satisfying your objective.

9 In triis case, trie objective is to capture at Site

10 10 and not let it get anywhere else. So what we

11 do is we only pump as high as we need to in order

12 to get that capture. Triere is no reason to pump

13 at a much'higher rate, because trien your

14 treatment costs go up. The treatment plant is

15 only designed to handle a certain capacity, so'

16 you can't juSt keep turning trie rates up.

17 ' Trie otrier triing about turning the

18 rates up is the aquifer can only take so much.

19 .You can only pull so mucri out of it before it

,2 0 can't give it up as.fast as you are trying to

21 pull it out. There is a balance and a number of

39

1 factors in terms of what you select .as your

2 pumping rates.

3 MR. FELTON: What is the capacity of

4 the treatment plant?

5 MR. DOERR: The treatment plant

'6 capacity is 300 gallons*, a minute. We are

7 currently running at about 100 to 110 gallons a

8 minute. The addition of triese four wells --

9 actually, trie four bedrock wells plus trie new

10 alluvial extraction well,, so triat' s five wells.

11 Triat's going to add about anotrier 45 to 50

12 gallons a minute, wriicri trie plant can riandle.

13 MR. .FELTON: ' If I were living in Bel

14 Air, I would wonder if trie Potomac River'was

15 capturing all of trie contaminated water or if it

16 migrit be cdming slowly lover into Bel Air and

17 Pinto..

18 MR. DOERR: We looked into triat. Triat

19 was a question a long time ago wrien we started

20 finding trie contamination at Sitel where we now

-21 have the groundwater extraction wells. We did

40

1 know that trie river was intercepting contaminated

2 groundwater, because trie same contamination we

3 were finding at Site 1, those same contaminants

4 were showing up in the river.

5 We were also concerned whether there

6 was a possibility that the contamination is going

7 under the river, and possibly contaminating

8 residential areas across the river. So we'did an

9 evaluation of the water on the other side of the

10 river. Not. just wriat the water cfuality was to

11 make sure we didn't have any of those same

12 contaminants, but we also measured the water

13 levels with respect to the water levels at our

14 facility and with respect to the water levels at

15 the river.

16 What we found is-trie water on trie

17, other side of the river is moving toward trie

18 river. Water on our side of the river is moving

19 toward' the river. So trie river,is cutting off

20 the water coming in both directions. In addition

21 to that, now we. have the extraction system down

41

1 at Site 1 which is capturing all of trie alluvial

2 and bedrock groundwater that used to discharge to

3 . that river. We are capturing it now. We are not

4 letting it discharge to the river anymore.

5 Any more questions or comments?

6 MR. HABERSACK: In your computer

7 simulation there it showed, like, various colors

8 of, like, streams of, I guess, water or was it

9 contamination or contaminated water?

10 MR. DOERR: Did you want to see this

11 one? The capture one (referring to Slide 27)?'

12 MR. HABERSACK: Yeah. Triat one triere.

13 Are they streams of underground water that I see

14 triere, or is that -- trie various colors there?

15 MR. DOERR: 'Imagine triat if you

16 took -- let's say you took a grain of salt and

17 you put in trie water and you watcried where it

18 went. Say you stuck it in right triere (referring

19 to Slide 27). Triis is sriowing where it would

20 flow before it got captured by the well.

21 The different colors -- what we wanted

I

42

1 to do is we want to make sure that- no matter

2 wriere the contamination was we captured it,

3 because we are talking about a thickness pf

4 contamination here. A thickness -- you have

5 . contamination in the alluvial aquifer -- at the

6 surface of the alluvial aquifer -- you have

. 7 contamination at 23 feet down at the bottom of

8 the aquifer right before you get into the bedrock

9 aquifer, and you have contamination down into the

10 bedrock aquifer. Triere was quite a vertical

11 distance of contamination.

12 We wanted to make sure that no. matter

13 where the contamination migrit be, our wells would

14 capture-it. So what these lines represent is a

15 different place along that vertical column where

16 we stuck that contaminant in to see where it

17 would'flow. Top of trie alluvial aquifer, bottom

18 of the alluvial aquifer, doWn in the bedrock.

19 That's wriat trie different lines represent.

20 . . Anytriing else? Thank you.

21 (Meeting concluded at 6:05-p.m.)

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on the cover sheet hereof and thereafter

transcribed by me to the best of my ability

Monicme Christiansen

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Documents

I ^'200s lih · CONTENTS 2.12.2 Descriptiori of Selected Remedy 2-24 2.12.3 Summary of Estimated Remedy Costs 2-26 2.12.4 Expected Outcomes of Selected Remedy 2-26