RECORD OF DECISION (ROD) FOR KINGS CREEK CHEMICAL …

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BUSH RIVER STUDY AREA

RECORD OF DECISION Kings Creek Chemical Disposal Site (EABR15-A) & 30th Street Landfill (EABR15-B) Operable Unit 2B

Final, May 2010 U.S. Army Garrison Aberdeen Proving Ground, Maryland

DISTRIBUTION RESTRICTION STATEMENT APPROVED FOR PUBLIC RELEASE: DISTRIBUTION IS UNLIMITED. # 9952-A-l

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BUSH RIVER STUDY AREA

RECORD OF DECISION Kings Creek Chemical Disposal Site (EABR15-A) & 30th Street Landfill (EABR15-B) Operable Unit 2B

Final, May 2010 U.S. Army Garrison Aberdeen Proving Ground, Maryland

DISTRIBUTION RESTRICTION STATEMENT APPROVED FOR PUBLIC RELEASE: DISTRIBUTION IS UNLIMITED. # 9952-A-l

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1. REPORT DATE ^DD/w/w-y/yy';

May 2010 2. REPORT TYPE

Technical 3. DATES COVERED (From - To)

4 . TITLE AND SUBTITLE

Record of Decision Operable Unit 2B Kings Creels Disposal Site (EABR15-A) and

30th Street Landfill (EABR15-B) Bush River Study Area Aberdeen Proving Ground, Maryland

5a. CONTRACT NUMBER

W91ZLK-04-0013

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

General Physics Corporation

5d. PROJECT NUMBER

5e. TASK NUMBER

Delivery Order No. 0018

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

General Physics Corporation 500 Edgewood Road, Suite 110 Edgewood, Maryland 21040

8. PERFORMING ORGANIZATION REPORT NUMBER

GP-R-123E10001

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Directorate of Public Works, Environmental Division IMNE-APG-PWE Aberdeen Proving Ground, Maryland 21010

10. SPONSOR/MONITOR'S ACRONYM(S)

1 1 . SPONSOR/MONITOR'S REPORT NUMBER(S)

12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for Public Release: Distribution is Unlimited. #9952-A-l

13. SUPPLEMENTARY NOTES

14. ABSTRACT

This Record of Decision presents the remedy selected by the U.S. Army and the U.S. Environmental Protection Agency (USEPA) Region III, and agreed to by the Maryland Department of the Environment, to address the Kings Creek Chemical Disposal Site (EABR15-A) and the 30th Street Landfill (EABR15-B) within the Edgewood Area. The Existing Cover with Land-Use Controls, Sjte Maintenance, and Monitoring was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act, as amended by the Superfund Amendments and Reauthorization Act, and the National Oil and Hazardous Substances Pollution Contingency Plan. This decision is based on the Administrative Record for these sites. The Selected Remedy is supported by USEPA Region 111 and the Maryland Department of the Environment, as necessary to adequately and cost-effectively protect human health and the environment.

15. SUBJECT TERMS

Bush River Study Area, Kings Creek Chemical Disposal Site, 30th Street Landfill, Land-Use Control, Maintenance, Monitoring

|I6. SECURITY CLASSIFICATION OF: a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified

17. UMITATIONOF

ABSTRACT

SAR

18. NUMBER

OF PAGES

72

19a. NAME OF RESPONSIBLE PERSON

Mr. Rurik Loder (DPW-ED) 19b. TELEPHONE NUMBER (Include area code)

410-436-7313 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18

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FINAL

RECORD OF DECISION

REMEDIAL ACTION AT THE BUSH RIVER STUDY AREA OPERABLE UNIT 2B

KINGS CREEK CHEMICAL DISPOSAL SITE (EABR15-A) AND

30™ STREET LANDFILL (EABR15-B) ABERDEEN PROVING GROUND, MARYLAND

SUBMITTED BY:

ENVIRONMENTAL DIVISION DIRECTORATE OF PUBLIC WORKS

U.S. ARMY GARRISON ABERDEEN PROVING GROUND EDGEWOOD, MARYLAND 21010

May 2010

DISTRIBUTION RESTRICTION STATEMENT APPROVED FOR PUBLIC RELEASE:

DISTRIBTION IS UNLIMITED: #9952-A-l


Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland Page i

TABLE OF CONTENTS

PARTI: DECLARATION 1

1 SITE NAME AND LOCATION 1

2 STATEMENT OF BASIS AND PURPOSE 1

3 ASSESSMENT OF THE SITES 2

4 DESCRIPTION OF THE SELECTED REMEDY 3

5 STATUTORY DETERMINATIONS 4

6 DATA CERTIFICATION CHECKLIST .̂ 5

7 AUTHORIZING SIGNATURES 5

PART 2: DECISION SUMMARY 7

1 SITE NAME, LOCATION AND DESCRIPTION 7

2 SITE HISTORY AND ENFORCEMENT ACTIVITIES 7

3 PUBLIC/COMMUNITY INVOLVEMENT 17

4 SCOPE AND ROLE OF RESPONSE ACTION 17

5 SITE CHARACTERISTICS 18

6 CURRENT AND POTENTLVL FUTURE LAND AND RESOURCE USES 28

7 SUMMARY OF SITE RISKS 29

7.1 HUMAN HEALTH 29

7.2 ENVIRONMENT 31

7.3 RISK MANAGEMENT CONSIDERATIONS 33

8 REMEDIAL ACTION OBJECTIVES 33

9 DESCRIPTION OF ALTERNATIVES 34

9.1 ALTERNATIVE 1: NO ACTION 35

9.2 ALTERNATIVE 2: MAINTENANCE OF EXISTING COVER WITH LUCs, SITE MAINTENANCE, AND

MONITORING 35

10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 36

10.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 36

10.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS 38

10.3 LONG-TERM EFFECTIVENESS AND PERMANENCE 38

10.4 REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT 38

10.5 SHORT-TERMEFFECTIVENESS 38

10.6 IMPLEMENTABILITY 38

10.7 COST 38

10.8 STATE ACCEPTANCE 38

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland Page ii

10.9 COMMUNITY ACCEPTANCE 38

10.10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 38

11 PRINCIPAL THREAT WASTES 39

12 SELECTED REMEDY 39

12.1 DESCRIPTION OF THE SELECTED REMEDY 39

12.2 LUC REMEDIAL DESIGN 42

12.3 SUMMARY OF THE RATIONALE FOR THE SELECTED REMEDY 43

12.4 SUMMARY OF ESTIMATED REMEDY COSTS 46

12.5 EXPECTED OUTCOMES OF SELECTED REMEDY 46

12.6 PERFORMANCE STANDARDS FOR THE SELECTED REMEDY 46

13 STATUTORY DETERMINATIONS 48

13.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 48

13.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS 48

13.3 COST-EFFECTIVENESS 48

13.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT TECHNOLOGIES TO

THE MAXIMUM EXTENT PRACTICABLE 49

13.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT 49

13.6 CERCLA 121(c) FIVE-YEAR REVIEW REQUIREMENT 49

14 DOCUMENTATION OF SIGNIFICANT CHANGES 49

PART 3: RESPONSIVENESS SUMMARY 51

1 OVERVIEW 51

2 BACKGROUND ON COMMUNITY INVOLVEMENT 51

3 SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC COMMENT PERIOD AND AGENCY RESPONSES 53

PART 4: REFERENCES 55

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland Page iii

L I S T O F F I G U R E S

FIGURE 1. LOCATION OF BUSH RIVER STUDY AREA IN ABERDEEN PROVING GROUND 8

FIGURE 2. LOCATION OF BUSH RIVER STUDY AREA AND OPERABLE UNIT 23 9

FIGURE 3. SITE FEATURES AND TOPOGRAPHY 11

FIGURE 4. OPERABLE UNIT 2 B MEDIA SAMPLING LOCATIONS..... 15

FIGURE 5. CSM FOR THE CHEMICAL DISPOSAL SITE 26

FIGURE 6. CSM FOR THE 30™ STREET LANDFILL 27

FIGURE 7. EXTENT OF RESTRICTED RESIDENTIAL LAND USE IN BUSH RIVER STUDY AREA 40

FIGURE 8. EXTENT OF EXCAVATION RESTRICTION WITHIN OPERABLE UNIT 2 B 41

FIGURE 9. SAMPLE NEWSPAPER ADVERTISEMENT 52

L I S T O F T A B L E S

TABLE 1. DATA SUMMARY (UPLAND SOIL) , , 22

TABLE 2. DATA SUMMARY (HYDRIC SOIL) 24

TABLE 3. SUMMARY OF RISKS ASSOCIATED WITH EXPOSURES TO SURFACE SOIL UNDER CURRENT AND

FUTURE LAND USE CONDITIONS 30

TABLE 4. REMEDIAL ALTERNATIVE EVALUATION CRITERIA ' 37

TABLE 5. APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS 45

TABLE 6. DETAILED COSTS FOR THE SELECTED REMEDY 47

L I S T O F A T T A C H M E N T S

ATTACHMENT A. MDE CONDITIONS OF VARIANCE: C O M A R 26.04.07

Record of Decision Bush River Study Area Operable Unit 2B Aberdeen Proving Ground, Maryland

Final May 2010

Page iv

ACRONYMS AND ABBREVIATIONS

AEDB-R Army Environmental Database - Restoration

AGO Area of Concem

APG Aberdeen Proving Ground

ARAR Applicable or Relevant and Appropriate Requirement

BRSA Bush River Study Area

CERCLA Comprehensive Environmental Response, Compensation and Liability Act

COC Constituent of Concem

COPC Chemical of Potential Concem

CFR Code of Federal Regulations

COMAR Code of Maryland Regulations

CWM Chemical Warfare Materiel

DDD 4,4'-dichlorodiphenyldichloroethane

DDE 4,4'-dichlorodiphenyldichloroethene

DDT 4,4'-dichlorodephenyltrichloroethane

DDTr DDT + DDE + DDD

EEQ Environmental Effects Quotient

EPC Exposure Point Concentration

FFA Federal Facility Agreement

FS Feasibility Study

GIS Geographic Information System

HHRA Human Health Risk Assessment

HI Hazard Index

HQ Hazard Quotient

IRP Installation Restoration Program

LECR Lifetime Excess Cancer Risk

L T M Long-Term Monitoring

LUC Land-Use Control

MDE Maryland Department of the Environment

msl mean sea level

|ig/L micrograms per Liter

mg/kg milligrams per kilogram


Final May 2010

Page V

NCP National Oil and Hazardous Substances Pollution Contingency Plan

NPL National Priorities List

O&M Operation and Maintenance

OSWER Office of Solid Waste and Emergency Response

OU Operable Unit

RAB Restoration Advisory Board

RAO Remedial Action Objective

RCRA Resource Conservation and Recovery Act

RD Remedial Design

RFA RCRA Facility Assessment

RG Remedial Goal

RI Remedial Investigation

ROD Record of Decision

SARA Superfund Amendments and Reauthorization Act

SVOC Semivolatile Organic Compound

SWMU Solid Waste Management Unit

TAL Target Analyte List

TCL Target Compound List

TRV Toxicity Reference Value

USAEC U.S. Army Enviroimiental Command (formerly the U.S. Army Envirormiental Center)

USAEHA U.S. Army Environmental Hygiene Agency (now the U.S. Army Center for Health Promotion and Preventative Medicine [USACHPPM])

USATHAMA U.S. Army Toxic and Hazardous Materials Agency (now the U.S. Army Environmental Command)

USEPA U.S. Envirormiental Protection Agency

UXO Unexploded Ordnance

VOC Volatile Organic Compound

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland Page vi


Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland Page 1

RECORD OF DECISION

REMEDIAL ACTION AT THE BUSH RIVER STUDY AREA OPERABLE UNIT 2B

KINGS CREEK CHEMICAL DISPOSAL SITE (EABR15-A) AND 30^" STREET LANDFILL (EABR15-B)

ABERDEEN PROVING GROUND, MARYLAND

May 2010

PARTI: DECLARATION

1 SITE NAME AND LOCATION

Two sites within the Edgewood Area of Aberdeen Proving Ground (APG), Maryland have been designated for Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) response action to address the impact of historical waste management practices. The sites comprise Operable Unit (OU) 2B within the Bush River Study Area (BRSA)! The BRSA, located in the northeastem portion of the Edgewood Area, occupies the peninsula between Lauderick Creek, the Bush River, and Kings Creek. U.S. Army CERCLA response actions are tracked in the Army Environmental Database-Restoration (AEDB-R). The two sites and corresponding AEDB-R Numbers are:

> Kings Creek Chemical Disposal Site (EABR15-A) and > 30* Street Landfill (EABR15-B).

CERCLA activities at APG are being conducted under a Federal Facility Agreement (FFA) signed on March 27, 1990. The U.S. Environmental Protection Agency (USEPA) Superfund Site Identification Number is MD 2210020036. This Record of Decision (ROD) is listed under OU-36 in USEPA's database.

2 STATEMENT OF BASIS AND PURPOSE

This ROD presents the remedy selected by the U.S. Army and the USEPA Region III and agreed to by the Maryland Department of the Environment (MDE) to address the two waste management sites within the Edgewood Area. The Selected Remedy is maintenance of the existing cover over the 30* Street Landfill, maintenance of shoreline erosion controls for both sites, and long-term monitoring of surface water, sediment, and groundwater. The Selected Remedy was chosen in accordance with CERCLA, as amended by the Superfund Amendments and Reauthorization Act (SARA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is based on the Administrative Record for these sites.

The U.S. Army, as the Federal lead agency, with the USEPA and the MDE, developed remedial altematives to achieve the Remedial Action Objectives (RAOs) for these sites. The Selected Remedy is supported by USEPA and MDE as necessary to adequately and cost-effectively protect human health and the environment.


3 ASSESSMENT OF THE SITES

Potential exists for risk to human health and the environment if no remedial action is undertaken.

At the Kings Creek Chemical Disposal Site, various metals and arsenic are present in soil at concentrations higher than background. While these constituents in soil do not pose unacceptable risk to future military/industrial workers or the ecosystem, the site would not be suitable for unlimited use and unrestricted exposure (e.g., family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use).

Investigation of the 30* Street Landfill revealed only inert materials (e.g., concrete, scrap metal) and chemical analysis of samples did not identify any unacceptable levels of contaminafion in soil. The invesfigation did not identify any risk to human health or the environment, or any site conditions that would make the site unsuitable for unlimited use and unrestricted exposure. However, it is possible that deeper subsurface material that has not been investigated could potentially contain hazardous constituents, including Munitions and Explosives of Concem (MEC), that would pose risk fi-om future excavation and placement of the material at the surface where exposure could occur. Therefore, the 30* Street Landfill would also not be suitable for unlimited use and unrestricted exposure.

The Selected Remedy is maintenance of the existing cover over the 30* Street Landfill, maintenance of shoreline erosion controls for both sites, and long-term monitoring of surface water, sediment, and groundwater. This containment altemative is consistent with the presumptive remedy for landfills. The selected altemative will prevent land use and actions that could result in unacceptable risk, thus attaining RAOs.

It is assumed that, throughout the BRSA, unlimited land use and unrestricted exposure woiild not be possible because a) constituents remain in surface media at concentrations that would pose unacceptable risk to hypothetical future residents; and/or b) the data, while sufficient to evaluate risk to military/industrial receptors and the environment, are not sufficient to evaluate risk for residential land use. However, the current and planned future use of the BRSA is for military/industrial activities. Therefore, it is anticipated that for all of the BRSA any active remediation of surface media as part of response actions will focus on protecting military/industrial workers and the environment. Therefore, this ROD includes an LUC prohibiting the use of the entire BRSA for family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use.

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


4 DESCRIPTION OF THE SELECTED REMEDY

The Selected Remedy for these sites includes LUCs, Site Monitoring and Maintenance of the Existing Cover, and Five-Year Reviews. The detailed approach and methodology will be specified in the Remedial Design (RD).

> Land-Use Controls: As mentioned previously, the current and planned future use of the BRSA is for military/industrial activities. LUCs will be implemented at BRSA to prevent site activities that would result in unacceptable exposure. A BRSA-wide LUC will prevent future family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use within OU 2B and the remainder of the BRSA. An OU-specific LUC will restrict excavation and other activities within OU 2B that could result in exposure of receptors to subsurface materials that potentially contain hazardous constituents. This LUC will also prevent disturbance of the existing shoreline stabilization stmctures and the existing vegetative cover, thereby maintaining remedy effectiveness into the fiiture. The site maps on Figure 7 and Figure 8 show the boundaries where the LUC objectives will be applied and maintained.

> Site Monitoring and Maintenance: Monitoring of site conditions will verify that the existing cover material at the 30* Street Landfill remains in place and protective of human health and the environment and that the shoreline erosion control measures remain in place, with maintenance being performed as necessary. As part of the shoreline erosion controls, a small arsenic hotspot near the discharge of the stream in the Chemical Disposal Area will be covered with rip-rap. The long-term maintenance together with long-term enforcement of LUCs will protect human health and the environment into the future; with long-term monitoring (LTM) providing verification.

> Five-Year Reviews: LTM and CERCLA 121(c) five-year reviews will be conducted to confirm the long-term effectiveness of the remedial response, including LUCs. Five-year reviews will be conducted in accordance with OSWER Direcrives 9355.7-03B-P and 9234.2-25, or their most current revision or replacement.

The RD will be submitted consistent with the RD schedule provisions of the FFA and will include the Site Maintenance, and Monitoring Plan, the LTM Plan, and the details of LUC implementation and maintenance (including periodic inspections).

The U.S. Army will be responsible for implementing, maintaining and enforcing the LUCs described in this ROD and the subsequent RD. As part of the U.S. Army's inspection and reporting responsibilities, periodic reviews of the restrictions and objectives outlined above will be undertaken and a review report will be submitted to USEPA and MDE. The LUCs will include implementation through the APG Master Planning System with Geographic Information System (GIS) support. As set forth in this ROD, the U.S. Army will not modify or terminate LUCs or implementing actions without prior approval of USEPA, after conferring with MDE. The U.S. Army will seek prior concurrence before taking an action that would dismpt the effectiveness of the LUCs.


Final May 2010

Page 4

If the U.S. Army transfers property in the areas addressed by this ROD, the U.S. Army will place a deed notification in the local property record that describes the restrictions on site activities and states that this notification is filed with the appropriate agencies, so that current and future property owners will be aware of these restrictions. Specific deed notification language and the appropriate agencies will be identified in the approved RD. While the U.S. Army maintains ultimate responsibility for LUC enforcement, the Army may require the transferee or lessee in cooperation with other stakeholders to assume responsibility for LUC implementation actions. Third-party LUC responsibility will be incorporated into pertinent contractual, property and remedial documentation, such as a purchase agreement, deed, lease and RD addendum.

To the extent permitted by law, a transfer deed shall require the LUCs imposed as part of a CERCLA remedy to run with the land and bind all property owners and users. If the U.S. Army intends to transfer ownership of any site, the Army may, if Federal and/or State law allows, upon transfer of fee title, grant the State an environmental covenant or easement that would allow the State to enforce LUC terms and conditions against the transferee(s), as well as subsequent property ovmer(s) or user(s) or their contractors, tenants, lessees or other parties. This covenant will be incorporated by reference in the transfer deed and will mn with the land in accordance with State realty law. This State enforcement right would supplement, not replace, the U.S. Army's right and responsibility to enforce the LUCs.

The selected remedial response is protective of human health and the environment. A cost summary is presented below:

Cost Summary

Capital Cost Operation and Maintenance (O&M) / LTM Costs Total Present Worth Costs O&M Time Frame Time to Achieve RAOs

$86,000 $1,263,000 $1,349,000

30 Years 6 Months

5 STATUTORY DETERMINATIONS

This remedial response meets the requirements of CERCLA Section 121 and, to the extent practicable, the NCP. The Selected Remedy is protective of human health and the environment; provides long- and short-term effectiveness; and complies with all Applicable or Relevant and Appropriate Requirements (ARARs) except the State of Maryland regulation for landfill closure, from which a variance has been granted (Attachment A). The Selected Remedy is at least as effective in protecting human health and the environment as a capping remedy would be, and does not destroy wetlands as would construction of a low permeability cap. A low permeability cap would not be an effective technology for preventing leaching at the 30* Street Landfill, because the waste is below the water table.

The Selected Remedy will result in hazardous substances, pollutants or contaminants remaining on site at levels that do not allow for unlimited use and unrestricted exposure.


Therefore, LUCs will be implemented to prevent site activities that would result in unacceptable exposure. These sites will be included in the consolidated five-year CERCLA remedy reviews of the Edgewood Area's National Priorities List (NPL) sites.

6 DATA CERTIFICATION CHECKLIST

The following information is included in the Decision Summary, Part 2 of this ROD. Additional information can be found in the Administrative Record file.

> Constituents of concem (COCs) and their respective concentrations (Decision Summary, Section 5).

> Baseline risk represented by the COCs (Decision Summary, Section 7).

> Remedial Goals (RGs) established for COCs and the basis for these goals (Decision Summary, Section 8).

> The absence of source materials constituting principal threats (Decision Summary, Section 11).

> Current and reasonably anticipated future land and groundwater use assumptions and potential land and groundwater uses that will be available as a result of the Selected Response Actions (Decision Summary, Section 6).

> Estimated capital, O&M, and total present worth costs, and the number of years over which the response cost estimates are projected (Decision Summary, Section 9).

> Key factor(s) that led to selecting the remedial response (i.e., describes how the Selected Response Actions provide the best balance of tradeoffs with respect to the balancing and modifying criteria, highlighting criteria key to the decision) (Decision Summary, Section 10).

7 AUTHORIZING SIGNATURES

The appropriate approval authority for this action is the APG Garrison Commander.

O J 1 4 - ^ • (QJ^^ - " - [ - ' ^ -Orlando W.Ortiz ^ Date Colonel, MI GarrisoruCommander

Kathryn A. Hodgkiss ' ^ Date Acting Director Hazardous Site Cleanup Division U.S. Environmental Protection Agency, Region III




PART 2: DECISION SUMMARY

1 SITE NAME, LOCATION AND DESCRIPTION

APG is an approximately 72,500-acre Army installation located in southem Harford and southeastem Baltimore counties, on the westem shore of the upper Chesapeake Bay (Figure 1). The installation is bordered to the east and south by the Chesapeake Bay; to the west by Gunpowder Falls State Park, the Crane Power Plant, and residential areas; and to the north by the City of Aberdeen and the towns of Edgewood, Joppatowne, Magnolia, and Ferryman. The Bush River divides APG into two areas: the Edgewood Area to the west and the Aberdeen Area to the east. The BRSA is in the Edgewood Area part of the APG NPL Site, USEPA Superfund Site Identification Number MD 2210020036. The site owner and lead agency is the U.S. Department of the Army, with USEPA as the lead regulatory agency and MDE as the supporting regulatory agency.

Established as the Ordnance Proving Ground in 1917, the Aberdeen Area of the installation became a formal military post, designated as APG, in 1919. Traditionally, APG's primary mission involved the testing and development of weapon systems, munitions, vehicles and a wide variety of military support materiel. The Edgewood Area (formerly Edgewood Arsenal) was appropriated by presidential proclamation in 1917 and has since been a site of laboratory research; field testing of chemical materiel and munitions; pilot-scale manufacturing; production-scale chemical agent manufacturing and related test, storage and disposal operations (U.S. Army Toxic and Hazardous Materials Agency [USATHAMA], 1983).

The Bush River Study Area lies in the northeast portion of APG's Edgewood Area and encompasses approximately 500 acres on a peninsula bounded to the north by Lauderick Creek, to the east and south by Bush River, and to the southwest by Kings Creek (Figure 2). As early as 1918, the Southem Bush River Area was used for training, test activities, waste disposal and chemical storage. The Kings Creek Chemical Disposal Site is an approximately 3.2-acre area adjacent to the north shore of Kings Creek (Figure 3). The 30* Street Landfill is an approximately 2.8-acre area south of 30* Street and adjacent to the northem shoreline of Kings Creek. Historically, the westem boundary of the 30* Street Landfill has been depicted as overlapping the eastem boundary of the Kings Creek Chemical Disposal Site. In reality, however, the area of overlap is occupied by mounds of construction and demolition debris that separate the OU 2B sites (Figure 3).

2 SITE HISTORY AND ENFORCEMENT ACTIVITIES

During 1984 and 1985, APG was evaluated as a potential NPL site. In 1985, the Edgewood Area of APG was proposed for inclusion on the NPL; it was listed in 1990. In 1986, between the time of the proposed listing and the final listing, a Resource Conservation and Recovery Act (RCRA) corrective action permit (MD3-21-002-1355) was issued by the USEPA Region III to address solid waste management units (SWMUs) in the Edgewood and Aberdeen areas of APG. As required by the RCRA permit, the U.S. Army Environmental Hygiene Agency (USAEHA) performed a RCRA Facility Assessment (RFA) for the Edgewood Area. The RFA identified sites in the Edgewood

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ABERDEEN PROVING GROUND CARTOGRAPHER:

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APPROVED BY:

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DATE:

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CARTOGRAPHER:

B. JOYCE

APPROVED BY:

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DATE:

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Area that were either SWMUs or areas of concem (AOCs) for potential contamination (USAEHA, 1989). After the final NPL listing of the Edgewood Area in 1990, fiirther investigations were conducted in accordance with CERCLA under the 1990 FFA with USEPA.

The FFA identified specific Study Areas within the Edgewood Area including Canal Creek, O-Field, J-Field, Carroll Island, Graces Quarters, Westwood, Lauderick Creek, and the BRSA. The Edgewood Area SWMUs and AOCs not specifically listed above were grouped and designated the Other Edgewood Areas.

In 1991, the Generic Work Plan for Remedial Investigation (RI) work at the Edgewood Area was published and divided known potential source areas into "clusters" of sites by geographic area. The BRSA contains seven clusters of sites numbered 3, 7, 11, 15, 18, 35, and 36.' The OU 2B sites are part of Cluster 15, in the Southem Bush River Area.

For purposes of completing Feasibility Studies (FSs) the Southem Bush River Area has been divided into the following OUs:

• OU 1: Surficial Aquifer Groundwater (southem and eastem plumes);

• OU 2A: 26* Street Disposal Site;

• OU 2B: Kings Creek Chemical Disposal Site and 30* Street Landfill; and

• OU 3: Toxic Gas Yard / RAD Yard and 22""̂ Street Landfill (including the Surficial Aquifer northem plume).

The Kings Creek Chemical Disposal Site was originally used as a chemical warfare materiel (CWM) disposal area; however, the date of initial site usage is not known. The earliest available aerial photograph fi-om 1929 indicates waste management activities already occurred at the site. The types of material fovmd at the site suggest activity occurred during the 1920s and 1930s, with first use probably occurring sometime between 1919 and 1922. Open buming and shallow burial were the primary methods of waste management. Interviews with personnel who worked in the BRSA during the World War II period indicate that waste management activities concluded during the late 1930s. Prior to 1990, the U.S. Army recovered a large amount of unexploded ordnance (UXO) disposed of at the site. The majority of the recovered material consisted of Livens projectiles and Stokes mortar rounds (all empty and destroyed), chemical filled munitions, and a large quantity of badly corroded Stokes mortar fiises at one location along the Kings Creek shoreline.

Approximately 2.8-acres in size, the 30* Street Landfill lies south of 30th Street, adjacent to the northem shoreline of Kings Creek, and immediately east of the Chemical Disposal Site. Aerial photography indicates activities within the 30* Street Landfill occurred during the late 1960s and/or 1970. The waste was pushed into the marsh to produce the fill area shown in Figure 3. The volume of waste disposed was small, and the surface

' Former Cluster 55 has been incorporated into Cluster 36.


elevation following the waste disposal activities remained low in the marsh area, not substantially higher than the elevation of surface water in Kings Creek. Following waste disposal activities, the disposal area naturally revegetated with Phragmites. Geophysical data, visual observations, and information fi-om test digs indicate that the bulk of the waste was placed into the center of the marsh, with waste remaining at the eastem edge of the Chemical Disposal Site where waste disposal was initiated consisting only of scattered demolition debris. The majority of the landfill waste lies in saturated, organic marsh sediment covered by dense marsh grass (i.e., phragmites). There is no documentation of the types of wastes placed in the landfill. Visual inspections have revealed building demolition debris, including concrete, steel and terra cotta pipes, and steam radiators, within the marsh area adjacent to the creek.

Several removal actions have been accomplished at the OU 2B sites. In 1992, a removal action of potentially contaminated surface waste occurred at the Kings Creek Chemical Disposal Site. Items removed fi-om the site included scrap metal, gas cylinders and approximately 50 drums (or drum remains). Contents of the drums removed fi-om the site included a tear gas agent, chloroacetophenone, and an unknown, inorganic crystalline solid. Large quantities of buried metallic objects were also identified along the westem edge of the 30* Street Landfill, where agent filled UXO items were recovered. In 1994, the U.S. Navy Explosive Ordnance Disposal Mobile Unit Two conducted near-shore underwater clearance operations within Kings Creek, immediately offshore of the Chemical Disposal Site. Fifty-one ordnance items were recovered, including seven explosive-configured munitions with suspect chemical fill, 33 suspect chemical fill munitions without explosives, and 11 high explosive or white phosphorus munitions. In 1996, the Edgewood Research, Development and Engineering Center Chemical Support Division removed surface debris fi"om the site.

In spring 2003, a time-critical removal action of laboratory glassware and ordnance fi-agments occurred within an eroded undercut bank on the Kings Creek shoreline in the southwestem part of the Chemical Disposal Site. Out of 56 recovered glass bottles/vials containing material, laboratory results identified mustard agent and/or the arsenical agent Lewisite in six of the bottles/vials. A temporary shoreline stabilization stmcture was installed at the southwestem part of the Chemical Disposal Site to reduce shoreline erosion. Excavation of this disposal pit was completed during a December 2003 removal action that recovered the remaining 29 glassware items. In 2006, ordnance items, scrap and debris was removed from within approximately 25 feet of the shoreline and permanent shoreline stabilization stmctures were constmcted.

RI field investigations were conducted from 1994 to 1997 at the two OU 2B sites. Activities included historical document and aerial photograph reviews, geophysical survey, installation of wells to monitor the groundwater, and the sampling of groundwater, surface water, sediment and soil. FS field investigations were completed between 1998 and 2003, and included geophysical surveys, test pit excavations, sampling and analysis of soil and sediment and toxicity testing of sediment. Additional sampling Eind analysis of soil was accomplished in 2007 to fill data gaps (GP, 2002b, 2008, 2009). Media sampling locations are illusfrated on Figure 4.

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MEDIA SAMPLING LOCATIONS

CARTOGRAPHER:

B. JOYCE DATE:

03-09-10

APPROVED BY;

J.HARRIS FIGURE:

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http://www.gpworldwide.com




3 PUBLIC/COMMUNITY INVOLVEMENT

CERCLA Sections 113 (K) (2) (A) and 117 and Department of Defense and Army policy require the involvement of the local community as early as possible and throughout the Installation Restoration Program (IRP) process. To accomplish this, APG is conducting monthly Restoration Advisory Board (RAB) meetings and periodic public meetings at each decision point in the CERCLA remedial process. The RAB membership is comprised of Army, regulatory agency and local community members. Progress of the OU 2B RI/FS has been discussed annually at RAB meetings since 1998. Remedial altematives for OU 2B were initially briefed during the July 2005 RAB meeting.

The remedial altematives evaluated for this ROD were briefed during July 2005, June 2006, July 2007, May 2008, and June 2009 RAB meetings. The OU 2B FS (GP, 2009) was finalized in May 2009.

The Proposed Plan for OU 2B was made available to the public on November 4, 2009. The Administrative Record, which contains the information used to select the remedial response, may be found at the Aberdeen and Edgewood branches of the Harford County Public Library and at the Miller Library at Washington College. The notice of the availability of these documents was published in The Aegis and The Cecil Whig on November 4, 2009, and Kent County News, The Avenue News, and East County Times on November 5, 2009. A public meeting was held on November 24, 2009. The public comment period was held from November 4 to December 18, 2009. Responses to the public comments received during this period are included in the Responsiveness Summary, Part 3 of this ROD.

4 SCOPE AND ROLE OF RESPONSE ACTION

This ROD addresses the final response actions for surface media (i.e., landfilled waste, surface and subsurface soil, sediment and surface water) within the Kings Creek Chemical Disposal Site and the 30* Sfreet Landfill, which comprise OU 2B within the BRSA. At the location of OU 2B, constituents in groundwater do not pose unacceptable risk and a response action addressing groundwater is not necessary. Monitoring of surface water, sediment, and groundwater at OU 2B will verity that future releases do not impact groundwater.

The Selected Remedy for OU 2B is protective of human health and the environment; provides long- and short-term effectiveness; and complies with all ARARs except the State of Maryland regulation for landfill closure, from which a variance has been granted (Attachment A).

It is assumed that, throughout the BRSA, unlimited land use and unrestricted exposure would not be possible because a) constituents remain in surface media at concentrations that would pose unacceptable risk to hypothetical fiiture residents; and/or b) the data, while sufficient to evaluate risk to military/industrial receptors and the environment, are not sufficient to evaluate risk for residential land use. However, the current and planned fiiture use of the BRSA is for military/industrial activities. Therefore, it is anticipated that for all of the BRSA any active remediation of surface media as part of response actions


will focus on protecting military/industrial workers and the environment. Therefore, this ROD includes an LUC prohibiting the use of the entire BRSA for family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use.

In the northwest portion of the BRSA the Old Bush River Road Dump, Lead Contaminated Soil Area, and Transformer Storage Area comprise Cluster 3. The Old Bush River Road Dump ROD, signed in 1999, selected a soil cover as the remedy. This remedy was designed to reduce the migration of contaminants by reducing infiltration, stabilizing the soil to prevent erosion, and containing the explosion of 4.2-inch chemical mortar shells that could be buried in the dump. The second Cluster 3 ROD, signed in 2005, selected excavation and on-site reuse, with ex-situ treatment as necessary, for the Lead Contaminated Soil Area and accepted the removal action as the final action for the Transformer Storage Area.

Groundwater in the surficial aquifer in the Southem Bush River Area of the BRSA is impacted with chlorinated volatile organic compounds (VOCs). The eastem and southem plumes of that impacted aquifer are being managed as OU 1. The northem plume is included in OU 3. Approximately 1,200 feet to the northeast of OU 2B is a former disposal area referred to as the 26* Street Disposal Site. Gas mask canisters were disposed by buming in a french along the west side of 26* Street, while wastes including dmms and radioactive wastes were dumped in a drainage swale on the east side of 26 Street. A removal action during the 1990s removed waste from the east side of 26* Street. The 26* Street Disposal site is being managed as OU 2A. The former Toxic Gas Yard / Rad Yard, the 22"'' Street Landfill and the former Ton-Container Steamout Site are located approximately 2,500 feet northeast of OU 2B. These surface units and the underlying surficial aquifer are managed as OU 3. Remedial responses for OU 1, OU 2A and OU 3 are being evaluated, proposed and implemented under separate FS, Proposed Plan and ROD documents.

5 SITE CHARACTERISTICS

The Kings Creek Chemical Disposal Site currently includes areas of dense, secondary growth forest, open areas devoid of vegetation where buming occurred, two open areas where dmms containing CWM had been stacked and bumed, and pieces of corroded scrap metal from the waste management operations. Ground surface elevation ranges between four and eight-feet above mean sea level (msl) and gently slopes toward Kings Creek (Figure 3). An 8-to-10-foot-wide drainage ditch lies within the cenfral portion of the site carrying surface mnoff from the inland areas and the site into Kings Creek.

The 30* Street Landfill primarily lies adjacent to and within the tidal, brackish (estuarine) wetlands of Kings Creek. Visual inspection of the landfill, including test digs, suggests the cover thickness (consisting of Phragmites root mat and soil) is approximately one to two feet. Ground surface elevation ranges between two and six feet above msl and gently slopes toward Kings Creek (Figure 3). Four drainage swales carry surface mnoff from the inland areas into the marsh area along the eastem portion of the landfill.


As a tidal creek, Kings Creek flows southeast and converges with the Bush River, an estuary of the Chesapeake Bay. Isolated areas of non-tidal, freshwater (palustrine) forested wetlands are upland of both sites. Tidal, brackish (estuarine) wetlands occupy the mouths of the drainage ditches and swales, within the 30* Street Landfill, and along the Kings Creek shoreline. Both sites experienced severe flooding with some shoreline erosion into Kings Creek from the effects of Tropical Storm Isabel from September 19 to 26, 2003. A temporary sand and gravel shoreline stabilization structure installed from April 30 to May 01, 2003 reduced the effects of shoreline erosion at the Kings Creek Chemical Disposal Site. Permanent shoreline stabilization stmctures were constmcted along the Kings Creek shoreline adjacent to the Chemical Disposal Site and 30* Street Landfill during 2006, eliminating the potential for COC release to Kings Creek via shoreline erosion.

The OU 2B sites lie within Harford County, Maryland. Harford County spans two physiographic provinces, the Piedmont and Atlantic Coastal Plain. The Piedmont contains crystalline basement rocks of Precambrian (more than 570 million years ago) and early Paleozoic age. In the Coastal Plain, unconsolidated sedimentary strata consisting of clay, silt, sand and gravel of Cretaceous, Tertiary and Quaternary age (144 million years ago to recent) unconformably overlie the crystalline rocks. The division between these provinces is known as the Fall Line. APG lies southeast of the Fall Line in the Coastal Plain. Coastal Plain sedimentary strata were deposited by sfreams, rivers and seas, forming a wedge-shaped body that slopes southeastward. These sedimentary sfrata comprise three stratigraphic units in the Bush River Study Area. From oldest to youngest, the units are the Potomac Group of Early Cretaceous age (97.5 to 144 million years ago), the Talbot Formation of Pleistocene age (1.6 million years ago), and recent alluvium. The Potomac Group is undifferentiated, consisting of sand and gravel interbedded with multicolored clay. The Talbot Formation is extremely variable because of the changing thickness of clay and sand facies and the presence of clay interbeds in gravelly sand facies. Alluvial deposits occur adjacent to and within drainage ways and topographic lows (GP, 2002b).

The surficial (water table) aquifer underlying the Southem Bush River Area qualifies as a potential source of drinking water, based on hydraulic parameters under both Federal and State aquifer classifications. The surficial aquifer is currently not used as a water supply. Groundwater for this area is not addressed in this ROD, because it will be addressed in the Southem Bush River Ground Water OUl ROD.

The vadose (unsaturated) zone at the Kings Creek Chemical Disposal Site contains dense clay, which results in mostly confined conditions for the surficial aquifer. The average depth to groundwater is 14 feet below grade, and the average thickness of the surficial aquifer is 10 feet thick. The bottom of the aquifer varies from 20 to 40 feet below grade. The surficial aquifer sediment consists of silty-sand to fine to medium grained, well sorted to poorly sorted sand, which is often interfingered with laterally discontinuous silt and clay layers in this heterogeneous aquifer. The surficial aquifer grades into offshore water-bearing units under Kings Creek, which consist of sand layers ranging from two-to-eight-feet-thick that are overlain by fine-grained, organic silt and clay. A dense, clay


confining unit over 40-feet-thick defines the base of the surficial aquifer and separates it from the deeper, confined Canal Creek aquifer.

Offshore and onshore geophysical surveys defined channel-fill sequences underlying the marsh area of the 30th Street Landfill. Up gradient of the landfill, the base of the surficial aquifer is approximately 40 feet below grade (33 feet below mean sea level). The main channel-fill sequence follows a northeast-to-southwest trend toward the creek, allowing the base of the aquifer to extend to an estimated 40 feet below grade (40 feet below mean sea level) under the landfill. Recharge areas for the surficial aquifer are within the center of the Southem Bush River peninsula. A broad main groundwater divide is located north of the OU 2B sites, resulting in groundwater flow from the north to the south through the sites and toward Kings Creek. Tidally influenced groundwater flow occurs toward the creek. Downward vertical hydraulic gradients occur within the upland areas, whereas upward vertical hydraulic gradients occur adjacent to the creek (GP, 2002a and 2002b).

The Southem Bush River Area contains forest, fields and wetiand habitats that support varieties of wildlife species and vegetation. Currently, there are no known occurrences of endangered plant or wildlife species in the Southem Bush River Area. Bald eagles, previously listed under Federal protection status as threatened, are known to forage in and around the Bush River Study Area. The closest known active nesting area is on the north shoreline of Lauderick Creek, approximately 3,000 feet north of the Southem Bush River Area.

Tulip, oak, maple, sweet gum and pine frees dominate secondary growth forest vegetation at the Southem Bush River peninsula. Typical forest species of the area include red fox, gray squirrel, white-tailed deer, woodpecker, crows and a variety of songbirds. Shrubs and native grasses are found in the open fields. Field species include field mice, voles, cottontail rabbits, bobwhites, mouming doves, killdeer, hawks and songbirds.

The wetland ecology in the Southem Bush River Area includes pockets of palustrine (freshwater) forested and emergent marsh environments. The majority of the wetlands in the area are estuarine (brackish water) emergent marsh environments. Wetland plants common to the palustrine emergent areas include phragmites, cattails and mshes. Palustrine forested areas contain red maple and sweet gum trees; while estuarine emergent species include phragmites, cordgrass, three squares, and mshes.

Wetland species include muskrats, turtles, snakes, great blue herons, puddle and diving ducks, and a variety of shorebirds, including spotted sandpiper, and rails. Estuarine fish that are expected to live in Kings Creek and the Bush River include largemouth and striped bass, carp, white and yellow perch, bluefish, catfish, sunfish, Atlantic silverside, and eels (ICF, 1997).

The former bum area occupied the southwestem portion of the Chemical Disposal Site, and was approximately two thirds of an acre in size. Historical aerial photography shows that the buming area was largely barren of vegetation when actively used prior to World War II. The historical photography also shows that the area barren of vegetation has shmnk in size since then, and now impact on vegetation is visible for only a very small


area (approximately 30 feet by 50 feet in size). The ground surface of approximately one fourth of the bum area was a mixture of ash, metal flake/fragments and soil during the 1980s. During the 20 years since then, there has been mixing of the soil, ash and organic matter from the ground surface, making the bum area less distinctive, with nearly all of the area that was barren of vegetation during the 1980s now vegetated. Soil samples were collected at 14 locations within the former buming area, with samples at three depths at 2 of the sampling locations, with the same depth intervals as for the drainage ditch samples. RI samples collected in 1993 were analyzed for Target Analyte List (TAL) inorganics and Target Compound List (TCL) volatiles, semivolatiles and pesticides/PCBs. Samples collected in 1998 and 2000 were analyzed for TAL metals, and 2003 samples were analyzed for all TAL and TCL compounds except semivolatile organic compounds (SVOCs).

The area of the debris mounds, approximately three quarters of an acre in size, is located along the eastem edge of the Chemical Disposal Site. This area is the location from which waste was pushed into the 30* Sfreet Landfill. Seven soil samples were collected within the debris mounds area. Arsenic was detected at concentrations ranging from 1.9 mg/kg (SS-113) to 12.7 mg/kg (SS-07) in these samples.

A drainage ditch through the Chemical Disposal Site originates north of the site and carries precipitation runoff in a south-southwesterly direction to Kings Creek (Figure 3). The ditch passes through the westem portion of the former bum area. Soil samples were collected from seven locations within or adjacent to the drainage. These soil samples were collected from either the top surface to 0.5-foot depth or surface to 1 foot depth, with the exception of location SS-90, where samples representative of the 0 to 1, 1 to 2 and 2 to 3-foot depth intervals were collected. Samples were analyzed for TAL metals. Detected concentrations of arsenic ranged from 2.51 mg/kg (SS-90-03) to 271 mg/kg (SS-92) in these samples.

Table 1 presents a statistical summary of the chemical analysis data for the bum area and upland surface soil samples. The concentrations of some metals, arsenic, and selenium are higher than background levels in a portion of the samples. Except for arsenic, the concentiations are only nominally higher than background.

Three of the 36 upland soil samples have arsenic concenfrations substantially higher than the background range for the eastem United States. As shown on Table 1, the median concenfration of arsenic in soil at this site is 6.7 milligrams per kilogram (mg/kg), only slightly higher than the median concentration (5 mg/kg) in soil of the eastern United States. RI/FS soil sampling initially identified two areas of elevated arsenic in soil; one in the drainage swale north of the Chemical Disposal Site and the second in the lower end of the drainage swale adjacent to Kings Creek. At the southem hot spot, supplemental sampling confirmed elevated arsenic concentrations within the lower 40 to 60 linear feet of the drainage swale, with a maximum detected concenfration of 268 mg/kg. This hotspot substantially skews the exposure point concentration (EPC), with a calculated value of 116 mg/kg which is above a safe risk level for arsenic. The Army plans to cover

Ail Upland Surface Soil Data

Table 1. Data Summary (Upland Soil)

Burn Area Surf SoH

Metals Aluminum Antimony Areenic Barium Beryllium Cadmium Calcium Chromium (total) Colialt Copper lion Lead Magnesium Manganese Mercury Nickel Potassium Selenium Silver Sodium Tlialiium Vanadium Zinc Explosive Related Compounds 2,4-DinitrotDluene Pestiddes 4,fH3DD l.l'-DDE 1,4'-DDT Aldrin alplia-BHC beta.BHC delta-BHC gamma^BHC (Undane) alpna<hlordane gamma^hlordane Dieldrin EndosulTan I Heptachlor Heptachlor Epoxide Mcthoxychlor Ph thab tesapAHs Bis(2<thylliexyi) PllUialate Diethyl Plittialate di-nOctyl Phthalate Anthracene Benzo(aJanttiracene Benza<a)pyrene Benzo(b)nuoranaiene Benzo(l()fluoranthene Chrysene Fiuoranthene Indeno(l,2,3.c,dJpyrene Phenanthrene Pyrene

Chlorororm Methylene Chloride Tetrachloroethene

Styrene Toluene 2-Butanone 2-Hexanone Cartion DisulTide

mg/i(g mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg nng/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

mg/kg

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg rr^/kg

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Freqof Detaction

36/36 9/36

36/36 36/36 32/36 24/36 36/36 36/36 32/36 36/36 36/36 36/36 35/36 36/36 37/41 35/36 35/36 17/36 9/36

32/36 0/36

35/36 36/36

1/6

9/16 13/16 14/16 1/16 1/16 1/16 1/16 1/16 1/16 1/16 6/16 2/16 1/16 1/16 1/16

6/6 1/6 1/6 1/6 1/6 1/6 1/6 1/6 2/6 1/6 1/6 1/6 2/6

2/16 1/16 4/16 1/16 1/16 4/16 5/16 2/16 1/16

Minimum Datsctsd

Value

345 0.61 1.90 10.8 0.05 0.06 31.4 4.5

0,56 3.2

. 4,890 7.6 16

14.1 0.024

1.64 135

0.541 0.19 39.7

7.21 4.5

0.1345

0.00085 0.00024 0.0O17

0.00078 0.00058 0.00025 0.00046 0.00072

0.019 0.021

0.00019 0.00033

0.0011 0.0024 0.0022

0.059 0.205 0.053 0.042

0.27 0.27 0.3

0.32 0.056 0.58 0.19 0.17

0.054

0.0015 0.0O435 0.0017 0.0017 0.053

0.0029 0.W16 0.0015 0.0091

Median Cone

7,025

6.70 40.0 0.25 0.13 190

14.4 2.6

14.95 13,450

27.0 793 61

0.080 6.1 366

0.31 0.09 92.0

22.3 23.7

0.00087 0.0032 0.012

0.24

Maximum Detected

Value

15,700 28.7 271

1,220 1.1 1.2

7,760 39.2 11.5 129

249,000 602

1,570 486

2.300 22.8 798

6.27 2.7 614

41.3 474

0.1345

0.26 0.096

0.19 0.00078 0.00058 0.00025 0.00046 0.00072

0.019 0.021

0.0027 0.0013 0.0011 0.0024 0.0022

1.9 0.205 0.053 0.042

0.27 0.27 0.3

0.32 0.29 0.58 0.19 0.17 0.37

0.02 0.00435

0.052 0.0017 0.053 0.055 0.046

0.0024 0.0091

FrBq> Bckgrnd

1/36 6/36 1/36

6/36 3/36 3/36

9/41

1/36 3/36

,2/36

Maximum Detected Freq >

Value Bckgrnd

10,400 0.99 158 4/15

99.7 0.47

1.2 1,770 31.6

5.9 89.7 2/15

249,000 2/15 47.7

1,200 486

0.17 22.8 798

6.27 1/15 0.19 370

38 104

0.02 0.029 0.19

0.0014 0.0013

1.4

0.02

0.0025 0.0017 0.053

0.0053 0.0025 0.0015 0.0091

HHInd Eco Soil Worker Soil

RBC COPC? ScrLev

1,022,000 409

NSSSL 0.27 SSL

1.91 c Yes 18 SSL 204,400

2,044 1,022

1,533,000 20,440 40,880

330 SSL 21 SSL

0.36 SSL

26 SSL 13 SSL 28 SSL

715,400 Yes NS SSL 1,000

20,440 102

20,440

5,110 5,110

71.5 1,022

306,600

2044

11.9 c 8.42 c 8.42 c

0.168 c 0.454 c

1.59 c

2.20 8.176 8.18

0.179 c

0.636 c 0.315 c 5110

204 c 817600

306600 3.92 c

0.392 c 3.92 c 39.2 c 392 c

40880 3.92 c

30660

10220 c 381.5 c

5.30 c 46.15 c

204400 81760

613200

102200

11 SSL

330 0.058

38 SSL

1.8 4.2 SSL

0.001 7.8 SSL 10

0.1 0.1 0.1 0.1 100 100

0.1 0.1 0.1 0.1

0.1 0.1 0.1

100 DOE

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.3 0.3 0.3

0,1 0,1

E COP

Yes Yes Yes

Yes

Yes

Yes

Yes

Yes Yes

Yes

Yes Yes

Yes

Yes

Yes Yes Yes Yes Yes Yes Yes Yes Yes

9SS UCL Eco of the

Mean Probability Distribution Function & Test

10.2 Non-parametric / 99% Chebyshev (Mean, Sd) UCL 116 Non.paramebic / 99% Chebyshev (Mean, Sd) UCL 216 Non.parametric / 95% Chebyshev (Mean, Sd) UCL

0.43 Lognormai / 95% H-UCL

17,4 Gamma / Approximate Gamma UCL

35,6 Lognormai / 95% H-UCL 53,411 Noniiararrebic / 95% Chebyshev (Mean, Sd) UCL

133 Nonîaramebic / 95% Chebyshev (Mean, Sd) UCL

160 Lognormai / 95% H-UCL 1,21 Non-parametnc / 99% Chebyshev (Mean, Sd) UCL

1,51 Non-parametric / 95% Chebyshev (Mean, Sd) UCL

25.9 Normal / Studenfs-t UCL 104 Lijgnormal / 95% H-UCL

0.23 Non-parametric / 99% Chebyshev (Mean, Sd) UCL

0.10 Gamma / Approximate Gamnu UCL

0.24 Nonnal / Studenfs-t UCL 0,24 Nonnal / Students-t u a 0,26 Gamma / Approximate Gamma UCL 0,27 Non-parametric / ModH X L (Adjusted fOr skewness) 0.26 Nonral / StudenCs-t UCL 0.41 Non-parameb-ic / Mod-t UCL (Adjusted for skewness) 0.22 Normal / Studenrs-t UCL 0.22 Normal / Studenf s-t UCL 0.29 Normal / Studenfs-t UCL

10.2 1161"

216

0.43

35.6 53,411

133

160 1.21

25.9 104

0.23

0.10

0,24 0,24 0.26 0.27 0.26 0.41 0.22 0,22 0,29

Notes: 1. A median concenb^bon is not shown for those constituents where the frequency of detection was low and detected concentraUons are estimated values below detection limits. 2. Sources of ecotogtal soil saeening levels are, in onjer of preference, USEPA Ecological Soil Saeening Levels (SSL), Benchmaric levels devekiped by the Deparbnent of Energy Oak Ridge (DOE) and USEPA Biological Technical Assistance Group, 3. Human carcinogens are identified by a "c" in the column adjacent to the soil RBC. 4. The concentrations of all metals except calcium, magnesium, potassium and sodium were compared to background and for Uiose metals with at least one detection higher than background, a frequency of occurance higher tiian background is shown. No entry in this column for a metal indicates that all detections were within background levels. 5. The EPC for arsenic is b^sed high by the kiwer drainage swale. Addressing this area under Alternative 2 would reduce the site EPC to 16.


this hotspot with rip-rap as an erosion contiol measure, thereby eliminating exposure and reducing the EPC to 16 mg/kg. Supplemental sampling at the northem arsenic hot spot did not detect elevated arsenic in soil, indicating that, if present, elevated arsenic is very limited in extent.

The median concentrations of antimony, barium, copper, iron, silver and zinc in soil at the OU 2B sites are lower than the median concentrations of these metals in soil of the eastem US, while the median levels of lead, mercury and selenium are only slightly higher than regional medians. The frequency of samples having concenfrations higher than the background range for the eastem United States is low for all metals except mercury, for which the frequency is relatively greater, but less than 30%.

Various pesticide, phthalate, polycyclic aromatic hydrocarbon and VOCs have also been detected at low concentrations in the OU 2B soil samples. Except for the pesticides DDD, DDE and DDT (collectively referred to as DDTr) that were detected in most samples, the frequency of detection was low. These organic constituents are not related to historical waste management activities.

Five samples of hydric soil were collected from beneath the Phragmites root mat in the 30* Sfreet Landfill where geophysics indicated the bulk of waste was disposed. Table 2 presents a statistical summary of the chemical analysis results for the hydric soil samples. Metals concentrations are typical of background concentrations. Trace concenfrations of DDTr and bis(2-ethylhexyl)phthalate were detected in the hydric soil samples, also typical of anthropogenic background levels and not indicative of disposal activities.

A total of 22 sediment samples and 14 surface water samples have been collected from Kings Creek adjacent to OU 2B to evaluate the potential for historical waste management activities to impact aquatic media (Figure 4). Detected constituents in sediment included metals, pesticides and several semivolatile organic compounds. The principal pesticides detected in sediment were DDT, DDD and DDE, present because of historical release into the headwaters of Kings Creek, with OU 2B not the source area. Scattered detections of several other pesticides at low microgram per kilogram (|ig/kg) concentrations were reported. Metals and selenium in sediment are within background ranges. Arsenic is only slightly above background, with a maximum detected concentration of 36 mg/kg. In surface water, metal/metalloid concenfrations are within reference background levels for regional waters. Trace concentrations of benzene in several samples are not OU 2B related, and may be due to motorboat activities.

During the RI/FS, groundwater samples were obtained from seven monitoring wells and one DPT point in the OU 2B vicinity. Four of the wells were sampled three times. These data indicated OU 2B is located on the fiinge of a VOC plume in the surficial aquifer originated well to the north of OU 2B. This plume will be addressed in the OU 1 ROD.

During 2007, an additional monitoring well was installed adjacent to the 30* Street Landfill. Previously existing wells were located east and south of the landfill area, and WBR-158 was installed at the north edge of the fill area where data was not previously available. USEPA requested WBR-158 to determine if contaminants exist in shallow

Table 2. Data Summary (30tt i Street Landfill Hydric Soil)

Metals Aluminum Antimony Arsenic Barium Beryllium Cadmium Calcium Chromium (total) rnhalt Copper Iron \K\(\ Magnesium Manga rtese Mercury Nickel Potassium Selenium Silver Sodium Thallium Vanadium Zinc

4,4'-DDD 4,4'-DDE • 4,4'-DDT Dieldrin Heptachlor Epoxide Phthalatesl tPAHs Bis(2-ethylhexyl) Phthalate

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

mg/kg mg/kg mg/kg mg/kg mg/kg

mg/kg

Freq of Detection

5/5 0/5 5/5 5/5 5/5 0/0 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 3/5 0/0 5/5 0/0 5/5 5/5

4/5 5/5 5/5 1/5 1/5

4/5

Minimum Detected

Value

2,900

2.00 35.3 0.34

311 10.9 2.7

15.1 13,200

9.7 521 52

0.026 6.3 362

0.37

272

18.1 21.9

0.00166 0.00084 0.0016

0.00054 0.00052

0.043

Median Cone

7,790

3.30 37.4 0.58

674 21.1

7.6 26.6

20,900 11.5

1,050 231

0.037 14.0 439

0.37

543

26.2 25.7

0.0042 0.00535

0.003

0.D45

Maximum HHInd Eco Detected Freq> Soil Worker Soil

Value Bckgrnd RBC COPC? ScrLev

9,630

4.85 48.1 1.95

2,530 32.4 31.4 42.7

27,600 30.2

1,210 989

0.280 24.8 845

0.76

706

33.6 66.35

0.02 0.041

0.22 0.00054 0.00052

0.061

1,022,000 409

NSSSL 0.27 SSL

1.91 c Yes 18 SSL 4,088 2,044 1,022

1,533,000 20,440 40,880

715,400 1,000

20,440 1/5 102

20,440

5,110 5,110

71.5 1,022

306,600

11.92 c 8.416 c 8.416 c

0.1789 c 0.3145 c

204.4 c

330 SSL 21 SSL

0.36 SSL

26 SSL 13 SSL 28 SSL NSSSL 11 SSL

0.058 38 SSL

1.8 4.2 SSL

0.001 7.8 SSL 10

0.1 0.1 0.1 0.1 0.1

100 DOE

E COP

Yes Yes Yes

Yes

Yes

Yes Yes

Yes

95% UCL Eco of the

Mean Probability Distribution Function & Test

4.26 Normal / Studenfs-t UCL

28.9 Normal / Student's-t UCL 24.4 Normal / Student's-t UCL 36.6 Normal / Student's-t UCL

26.0 Normal / Studenfs-t UCL

0.331 Gamma / Approximate Gamma UCL

30.9 Normal / Studenfs-t UCL 60.4 Normal / Studenfs-t UCL

0.48 Non-parametric / 99% Chebyshev (Mean, Sd) UCL

EPC

4.26

28.9 24.4 36.6

26.0

0.28

30.9 60.4

0.22

Notes: - A median concentration is not shown for those constituents where the frequency of detection was low and detected concentrations are estimated values below detection limits.

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland ^ Page 25

groundwater 8-10 feet below grade immediately adjacent to the fill area. Potential contaminants discharging from the fill to the upper aquifer section would be detected because of the proximity of the well to the fill area and the influence of daily tidal fluctuations from the creek on the aquifer. In addition, WBR-llOA/B and WBR-105 also provide for monitoring of potential contaminants within the aquifer. USEPA and MDE have concurred that the groundwater sampling and analysis results, together with the surface water data, indicate that the Chemical Disposal Site and the 30* Street Landfill are not releasing constituents to groundwater or surface water; however, the potential still exists for buried waste present in the 30* Street Landfill to release contaminants to groundwater or surface water in the fiiture.

Prior to the CERCLA removal actions, the possible mechanisms for contaminant transport at the OU 2B sites were: (a) shoreline erosion exposing waste with potential for release of constituents to Kings Creek sediment and surface water, and (b) erosion and sediment transport during precipitation events. Constituent tiansport via leaching and groundwater tiansport should not be significant because of the low permeability clay overlying the surficial aquifer.

The shoreline erosion was the principal mechanism for exposing and transporting subsurface waste, creating potential for exposure of human and ecological receptors to hazardous materials. This mechanism for exposure and transport of waste and constituents has been eliminated by the shoreline stabilization accomplished under removal actions. Removal actions have also eliminated surface wastes from the site, thereby removing the potential for erosion and sediment transport to create risk to human and ecological receptors. Constituents remaining in soil from historical waste management activities are limited to metals that are nominally higher than background in small localized areas.

A Conceptual Site Model (CSM) is an integrated representation of the physical and environmental characteristics of a site, as well as the complete, potentially complete, and incomplete exposure pathways between sources of contaminants at a site and potential human and environmental receptors. For a potential risk to be associated with a contaminant release, a complete pathway from the source to a receptor must exist, and the receptor must be present when the contamination arrives or still exists. In addition, the CSM documents when an uncertainty is or is not significant, i.e., illusfrates why data collection activities are or are not needed to support the decision-making process. Figures 5 and 6 are graphical depictions of the CSMs for the Chemical Disposal Site and the 30* Street Landfill.

Human exposure to surface water or sediment is.possible but precluded by site security and natural site conditions such that if it were to occur, frequency and duration would be too low to be of concem given that most analytes are at or near typical background levels. Sediment bioassay tests did not identify any toxicity associated with chemical constituents in sediment.

Kings Creek

Figure 5. Kings Creek Chemical Disposal Site Conceptual Site Model

Kings Creek

Figure 6. 30^^ Street Landfill Conceptual Site Model


The pathways of potential concem are those related to surface soil. However, surface soil analytes are at or near background levels with copper, lead, mercury, selenium, and zinc nominally above background. Arsenic is also nominally above background except in one localized area along the drainage ditch through the site. Elevated iron occurs only in the former bum area associated with metal flake in the soil.

6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USES

The U.S. Army currently uses the Edgewood Area for military/industrial land use activities. According to the APG Real Property Master Plan, current and planned fiiture use of BRSA is for supply and storage areas.

APG lies adjacent to the Chesapeake Bay, approximately 20 miles northeast of Baltimore, Maryland, with most of the installation lying within Harford County. Major rail and road corridors run through southem Harford County. Major road corridors include U.S. Interstate 95, U.S. Route 40, Maryland Route 7, and Maryland Route 24. Extensive passenger and cargo rail tiaffic travels on the Amtiak and Conrail lines that run northeast to southwest along the APG installation boundary.

Land use surrounding APG is a mix of commercial and residential use, but also includes some agricultural use. Industry is most concentrated along Route 40. Primary population centers within eight miles of the Edgewood Area include the communities of Joppatowne/Magnolia (population 11,391); Edgewood (population 23,378); and Bel Air (population 75,523). Smaller communities surrounding the Edgewood Area include Abingdon, Belcamp, Chase, and Van Bibber. The 2005 population of Harford County was 234,715 (www.census.gov).

APG has substantial workforce and military-residential populations. The APG workforce numbers approximately 18,000 people and is projected to reach approximately 22,000 by 2012. Approximately 2,000 military dependents reside at APG. In the Edgewood Area, the workforce and residential areas are concenfrated in the northem portion of the facility. As part of the "APG 2012 Transformation" Program, improvements will be made to infrastmcture, facilities, and services at APG over the next few years. Several facilities, including the new U.S. Army Medical Research Institute of Chemical Defense (MRJCD) Campus, are being constmcted within the Edgewood Area as part of this program and in response to Base Realignment and Closure (BRAC) activities. Enhanced use leasing options are also being considered for parcels adjacent to the northem boundary of the Edgewood Area, by the Maryland Department of Transportation and Northeast Maryland Waste Disposal Authority. Currently, there are no plans for BRAC development within the BRSA.

By 1918, the BRSA was being used for tiaining and test activities as well as for CWM storage and waste disposal. During World War I and World War II, the area served as a storage and tiansshipment depot for chemical-filled munitions and included a large dock for off- and on-loading of CWM.

http://www.census.gov

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland ^̂ Page 29

Historically, the southem portion of the peninsula, designated as A-Field, was the location of activities such as artillery firing, training, and testing. It also housed smoke and incendiary munitions testing facilities.

The lower two-thirds of the peninsula have been used in the past for the storage of chemical agents and materials needed for various operations in Edgewood Area. It is currently used to store hazardous wastes and materials in preparation for off-site disposal. Mustard agent was stored in bulk and later demilitarized at the former secured area. The OU 2B sites are currently not in use.

Recreational activities on the Edgewood Area include hunting, trapping, shoreline fishing and crabbing, boating, sports and picnicing. Recreational sites are used by active and retired military personnel and families, as well as civilians. The water areas of the Gunpowder and Bush Rivers adjacent to the Gunpowder Neck are used extensively by recreational boaters. Numerous boat ramps and marinas provide access to the Gunpowder and Bush Rivers. The waters of APG support both commercial and recreational fishing. Boat tiaffic within the installation boundaries is restricted by range control during firing exercises and enforced by APG patrol boats. There are no designated recreational areas within the BRSA. The Army has posted no trespassing signs on shorelines informing potential tiespassers of UXO dangers. Access to the area is limited to properly cleared personnel or individuals in an escorted capacity. A wide variety of physical security countermeasures, including barrier systems, sensors and random patrols by law enforcement personnel, are in place to prevent unauthorized access.

7 SUMMARY OF SITE RISKS

7.1 Human Health

The purpose of the Human Health Risk Assessment (HHRA) is to determine whether exposure to site-related contaminants could adversely affect human health. The HHRA estimates risks the site poses under current or potential fiiture use conditions if no remedial action were taken. The risk is expressed as the lifetime excess cancer risk (LECR) for carcinogens, and Hazard Index (HI) for non-cancer adverse health effects.

Using receptor exposure routes, exposure point concenfrations, and chemical toxicity data, LECRs for carcinogenic chemicals and HI values for chemicals having noncarcinogenic effects were estimated. The acceptable range for the LECR is from 1E-66 to 1E-04. An LECR of 1E-06 represents the probability that one person will confract cancer as a result of exposure to site related contaminants in a population of one million people exposed. An LECR of 1 E-04 represents the probability that one person in ten thousand exposed individuals will confract cancer as a result of exposure to site-related contaminants.

A Hazard Quotient (HQ) is derived for each contaminant by comparing the anticipated level of exposure or dose to a receptor to the reference dose for that exposure scenario at which no adverse health effects occur. The HQs for all contaminants affecting a given exposure route or organ are summed to give the HI. The estimated non-cancer HI values


Final May 2010

Page 30

are then compared to a value of 1.0 to determine whether any non-cancer effects are anticipated from exposure to site contaminants. An HI value above 1.0 indicates a potential for adverse health effects.

Conclusions from the original Baseline Risk Assessment for Southern Bush River Area (ICF, 1997) for exposure to site-wide surface soil under current and future land use conditions are provided in Table 3.

Table 3. Summary of Risks Associated with Exposures to Surface Soil Under Current and Future Land Use Conditions

Cancer Receptor/ Risk Pathway (LECR)

Predominant Chemicals*

Non-Cancer (HI)

pft'i^'^-f->î^K5g-^MKM¥^&^ Site Worker:

Incidental Ingestion 2E-06 Dermal Contact 5E-06

Arsenic Arsenic

f:'f% ^-l' 'i': • Viij^:i|{v%î?S''^>'FuturerEa Site Worker:

Incidental Ingestion 2E-06 Dermal Contact 5 E-06

Trespasser: Incidental Ingestion 5E-07 Dermal Contact 5E-07

Hypothetical Resident Child: Incidental Ingestion 1E-05 Dermal Contact 4E-06

Hypothetical Resident Adult: Incidental Ingestion 7E-06 Dermal Contact 4E-05

Arsenic Arsenic

NA NA

Arsenic Arsenic

Arsenic Arsenic

<1 (lE-02) <1 (3E-02)

f:-\ V-:---,l-.'i'";̂ ^

<1 (lE-02) <1 (3E-02)

<1 (7E-03) <1(8E-03)

<1 (3E-01) <1(1E-01)

<1 (4E-02) <1 (2E-01)

Predominant Chemicals*

'mmminm^m NA NA

'PAmg:W:^m:

NA NA

NA NA

Arsenic Arsenic

Arsenic Arsenic

NA Not applicable * Predominant chemicals were associated with a cancer risk greater than 1 E-06 or HI greater than

Under current land-use conditions, the cumulative LECR for workers based on exposures to surface soil was 7E-06. The cumulative non-cancer HI was less than 1.0 (4E-02). Under fiiture land-use conditions, the cumulative LECR for site workers was assumed to be the same as current land-use for exposure to soil. The cumulative LECR and HI for trespassers under future land-use conditions were lE-06 and 0.02, respectively. The cumulative LECRs for hypothetical fiiture child and adult residents were 1 E-05 and 4E-05, respectively (primarily due to exposure to arsenic). The cumulative non-cancer His for hypothetical fiiture child and adult residents were both less than 1.0 (0.4 and 0.2, respectively).

Several years after completion of the HHRA, a site-specific evaluation of the OU 2B upland soil data was conducted in support of the FS. The results from this evaluation indicated that only arsenic and iron are constituents of potential concem for industrial workers. The highest concentrations of arsenic in soil at the Chemical Disposal Site were confirmed in the southem portion of the drainage swale adjacent to Kings Creek (268


mg/kg). The maximum detected concenfration of iron (249,000 mg/kg) was observed in soil from the former bum area (Table 1). Risk assessment calculations indicate that HQs for both iron and arsenic are less than 1.0 for industrial workers, and carcinogenic risk associated with arsenic is within the lE-06 to lE-04 acceptable risk range for workers. Arsenic and other constituents including iron and lead are present in soil in small areas at concentiations that may pose unacceptable risk to hypothetical fiiture residents^. Therefore, the Kings Creek Chemical Disposal Site would not be suitable for unlimited use and unrestricted exposure.

For the hydric soil samples collected at the 30* Street Landfill, the only constituent with a detected concentration exceeding a soil Risk-Based Concentration for either industrial or residential land use is arsenic, for which concentrations ranged from 2.0 to 4.85 mg/kg (Table 2). The arsenic concentiations are within background levels, and associated risk is within the 1 E-06 to 1 E-04 acceptable risk range for both land uses.

Investigation of the 30* Sfreet Landfill revealed only inert materials (e.g., concrete, scrap metal) and analysis of samples did not identify any contamination of soil. The investigation did not identify any risk to human health or the environment, or any site conditions that would make the site unsuitable for unlimited use and unrestricted exposure. However, it is possible that deeper subsurface material that has not been investigated could potentially contain hazardous constituents, including MEC, which would pose risk if there were fiiture excavation and placement of the material where exposure could occur. Therefore, the 30* Sfreet Landfill would also not be suitable for unlimited use and unrestricted exposure.

7.2 Environment

The Baseline Risk Assessment for Southern Bush River Area (ICF, 1997), evaluated all soil samples in the Southem Bush River Area as one data grouping in the ecological risk assessment. Chemicals of potential concem (COPCs) were selected based on a screening comparison of on-site concenfrations to Region III Screening Levels and reference background concentrations. Exposure concentrations for the COPCs were then compared to Toxicity Reference Values (TRVs).

The COPCs identified during the ERA for site-wide soil included several VOCs, PAHs, phthalates and phenols, and inorganics^. Of these, DDTr and a few metals (aluminum, cadmium, chromium, copper, mercury, vanadium, and zinc) were identified as having the potential to adversely affect ecological receptors within the Southem Bush River Area. With the exception of mercury and DDD, mean site concentiations of these COPCs were

The data quality objectives for OU 2B were developed based on future military/industrial land use. The number, depth, and spatial distribution of samples, while appropriate for that land use, are not sufficient to fully assess risk to hypothetical future residents.

Arsenic was not selected as a surface soil COPC, because it was detected below the Region III Screening Level of 328 mg/kg


within the range of reference background. Maximum concentrations of mercury were detected outside of OU 2B, at the Chemical Munitions Burial Site 3 (Cluster IS)'^.

As part of the OU 2B FS, site-specific soils data were screened against ecological benchmarks to identify constituents that would be evaluated as COPCs in an ecological risk assessment. The benchmarks that were used, in order of preference, are USEPA Ecological Soil Screening Levels (Eco-SSLs), USEPA Region III Biological Technical Assistance Screening Levels, and for constituents where these screening levels are not available, benchmarks developed by the US Department of Energy Oak Ridge Laboratory. The results of this screening are presented in Table 1.

While the maximum detected concentrations of a number of organics exceed ecological screening levels, these detections are in only a few samples, and there is no substantial potential for these constituents to impact the area ecosystem.

In the upland soils, the maximum detected concentrations of many metals exceed ecological screening levels. For all of these metals except mercury, the frequency of occurrence higher than background is low (Table 1). Of these metals, only for arsenic are detections substantially higher than background, and these high arsenic concentrations are limited to two small areas along the drainage ditch through the site. For the other metals, with a small frequency of occurrence higher than background, and those concentrations only nominally higher than background, there is no substantial potential for these constituents to impact the area ecosystem.

Mercury is present in approximately 30% of the soil samples at concentrations higher than background. The highest detected mercury concentration was 2.3 mg/kg in sample SS-119. Four additional soil samples were taken around and at a distance of 20 feet from the SS-119 location, with analysis for only mercury. Mercury was also found to be higher than background in these samples, but at lower concentrations between 1 and 2 mg/kg. At OU 2B, the upland soils have a median concentration of 0.08 mg/kg, a mean of 0.32 mg/kg, and a maximum detected level of 2.3 mg/kg. While higher than background, mercury in soil is not so high as to require fiirther evaluation.

The highest concentrations of metals in soil are potentially phytotoxic. However, the fraction of samples and fraction of area with elevated concentrations are small. The only visible impact on vegetation is a small area barren of vegetation in the former bum area where the top 6 inches is a mixture of soil, ash and small metal fragments/flakes. The impact on vegetation may be due as much to the nature of the soil/ash/metal flake mixture as to the concentrations of metals. Pesticides in soil are present only at low concenfrations in scattered locations, and are not associated with historical military activities.

The hydric soil within the marsh is uncontaminated, with only tiace levels of pesticides and phthalate typical of anthropogenic background. Metals concentrations are typical of

In 1999, a removal action was conducted to remove mercury-contaminated soil and waste fi-om Chemical Munitions Burial Site 3. This action eliminated potential wildlife exposure to contaminated soil at the site and reduced additional shoreline erosion into Kings Creek.


background for the eastem United States. The results of the screening for the hydric soils are presented in Table 2. No constituents in hydric soil pose unacceptable risk to human health or the environment.

7.3 Risk Management Considerations

Most of the initially existing risk to human health and the environment from waste at the Kings Creek Chemical Disposal Site and the 30* Street Landfill has been mitigated through conduct of CERCLA removal actions. Surface waste that was potentially hazardous has been removed. Chemical ordnance has been removed from the ground surface and from shallow water along the shoreline. Laboratory waste in a shallow burial trench along the shoreline has been removed. The shoreline stabilization along the shoreline of both the Kings Creek Chemical Disposal Site and the 30* Sfreet Landfill prevents the exposure of any remaining subsurface waste that is potentially hazardous in nature via shoreline erosion, the mechanism that was most likely to create risk.

While arsenic, lead, and iron concentrations in soil in hot spots may pose unacceptable risk for fiiture residential land use, there are no constituents in environmental media that pose unacceptable risk to military/industrial workers or the environment. Test digs at the 30* Stieet Landfill have not identified buried waste that could release toxic constituents to media (only debris and inert materials found). However, it is expected that subsurface UXO remains at the Chemical Disposal Site. This potential hazard is mitigated by APG standard operating procedures and may be addressed by the Military Munitions Response Program. While the waste recovered during test digs and sampling and analysis has consisted of only debris and inert materials at the 30th Street Landfill, there is a regulatory concem that buried waste or containers that may be present in the fill could release constituents in the future and pose an unacceptable risk that is not apparent now.

8 REMEDIAL ACTION OBJECTIVES

RAOs are goals developed for the protection of human health and the environment. These objectives can be achieved by reducing exposure (e.g., capping an area or limiting access) as well as by reducing the concentiation level of COCs.

The RAOs for OU 2B are:

> Prevent land use that would result in unacceptable risk to residential receptors (family housing, elementary and secondary schools, child care facilities, playgrounds and other residential land usage) through exposure to site-related contaminants; and

> Prevent direct exposure to subsurface materials that potentially contain hazardous constituents.

Remedial Goals and Performance Standards

Because there is no unacceptable risk to either industrial workers or ecological communities, there are no COCs, and no media of concem. Therefore, no RGs have been developed for protection of workers or the environment. The disposed waste within the 30* Street Landfill has not been fiilly characterized. There is no need to develop RGs for


constituents that possibly exist in waste, because the presumptive containment remedy will prevent exposure to constituents in waste.

Maintenance of the existing shoreline stabilization stmcture includes erosion control measures in areas adjacent to the stmcture. The two areas most subject to erosion are a small barren area in the southeast comer of the Chemical Disposal Area and the drainage swale through the Chemical Disposal Site, through which a large volume of water flows when floodwaters recede after a hurricane storm surge. Preventive maintenance will involve placement of stone in the lower portion of the drainage swale, and stabilization of the barren area by either placement of stone or by placement of topsoil with subsequent seeding to establish vegetation. These same two areas have been of regulatory concem because of the barren nature of the one site and because there is an arseriic hot spot in the lower portion of the drainage swale. While the risk associated with these two sites is not sufficient to trigger remedial action under CERCLA, the preventive maintenance to control erosion will also reduce exposure and address regulatory concem. The stabilized drainage swale will be maintained as part of the shoreline stabilization stmcture, and will also be protected by the LUC that prohibits disturbance of that stmcture.

9 DESCRIPTION OF ALTERNATIVES

A summary description of remedial altematives evaluated in detail during the FS is presented below. For purposes of cost comparison, project duration of 30 years is assumed for all altematives.

Three remedial altematives were developed for OU 2B. These preliminary altematives were screened for effectiveness, implementability, and cost. Two were retained for detailed evaluation: Altemative 1 (No Action) and Altemative 2 (Maintenance of Existing Cover with LUCs, Site Maintenance, and Monitoring).

Altemative 3 (Low Permeability Cap with LUCs, Site Maintenance and Monitoring) was eliminated during the initial screening in the FS, for several reasons. From a constmction and long-term maintenance standpoint, a low permeability cap would be more problematic at the 30* Stieet Landfill than at a typical upland sanitary landfill. The landfilling was into a marsh, with a limited amount of compaction, and the cover contains a substantial amount of organic matter. It is possible that there would be substantial settling following constmction, which could damage/compromise the low permeability layers of the cap. Constmction of the low permeability cap would also result in the destmction of more than an acre of wetland, requiring wetlands permitting and mitigation. This type of action cannot be justified for this site when hazardous constituent releases have not been observed from the landfill to groundwater, surface water, sediment, or surface soil. Further, the primary advantage to a low permeability cap is the prevention of leaching. Most of the waste at this site is present beneath the water table; therefore, the low permeability cap cannot prevent water from infiltrating the subsurface materials. Because the low permeability cap is no more effective than the existing cover material in protecting human health and the environment, at a substantially higher cost, Altemative 3 has not been retained for detailed altemative development.


9.1 Altemative 1: No Action

The NCP requires consideration of "No Action", as a baseline with which to compare other altematives (40 CFR 300.430(e)(6)). Under this altemative, LUCs would not be implemented and existing institutional controls, such as APG standard operating procedures, may not continue.

Estimated Capital Cost: $0 Estimated O&M /LTM Cost: $0 Estimated Total Present Worth Cost: $0 Estimated O&M Timeframe: None Estimated Time to Achieve RAOs: Will not achieve

9.2 Alternative 2: Maintenance of Existing Cover with LUCs, Site Maintenance, and Monitoring

This altemative involves containment of the landfilled waste, which is a presumptive remedy for landfills. The existing landfill cover would be maintained, preventing direct exposure to underlying waste, with natural vegetation and the shoreline stabilization stmcture preventing soil erosion. A BRSA-wide LUC would prevent family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use within OU 2B and the remainder of the BRSA. An OU-specific LUC would restrict excavation and other activities within OU 2B that could result in exposure of receptors to subsurface materials that potentially contain hazardous constituents or munitions. The LUC would include signs to wam that excavation without prior approval is not permitted. This LUC would also prevent disturbance of the existing shoreline stabilization stmctures, thereby maintaining their effectiveness into the future. Monitoring of site conditions would verify that the shoreline erosion contiol measures remain effective and that the existing soil and natural vegetation cover at the 30* Street Landfill remains in place and protective of human health and the environment. Long-term monitoring of surface water, sediment, and groundwater would be conducted to verify that there are no future releases to the environment.

The 30th Sfreet Landfill was created by landfilling into a tidal marsh. The landfilled waste lies beneath the water table. The existing cover consists of dense phragmites that discourages access in addition to providing cover. The existing cover soil is uncontaminated and does not contain constituents at concentrations that pose risk to either human health or the environment. Because of these factors, a low-permeability cap or additional cover soil would not protect human health or the environment to a greater extent than the existing cover, provided that the existing cover is maintained.

The existing soil and natural vegetation cover does not meet the State of Maryland regulation for landfill closure. The U.S. Army submitted an application for a variance to the requirements of COMAR 26.04.07.21 which relate to closure of sanitary, mbble and industrial waste landfills, including specifications for low permeability closure caps. The variance was granted by the MDE (Attachment A) in accordance with COMAR 26.04.07.26, because the existing cover for the 30* Stieet Landfill conserves and protects


public health and environment to at least the same extent as would be obtained by a low permeability cap at this site. The conditions for acceptance of the variance (detailed in Attachment A) include: i) LUCs preventing residential land use and disturbance of the subsurface materials; ii) long-term monitoring of the existing cover material and shoreline erosion control measures; and, iii) long-term monitoring of groundwater, surface water, and sediment.

The two areas most subject to erosion are a small barren area in the southeast comer of the Chemical Disposal Area and the drainage swale through the Chemical Disposal Site. Preventive maintenance will involve placement of stone in the lower portion of the drainage swale, and stabilization of the barren area by placement of topsoil with subsequent seeding to establish vegetation. The stabilized drainage swale will be maintained as part of the shoreline stabilization stmcture, and will also be protected by the LUC that prohibits disturbance of that stmcture.

Estimated Capital Cost: $86,000 Estimated O&M/LTM Cost: $1,263,000 Estimated Total Present Worth Cost: $1,349,000 Estimated O&M/LTM Timeframe: 30 Years Estimated Time to Achieve RAOs: 6 Months

10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

The following is a comparative analysis of the remedial altematives considered for OU 2B. The potential performance of each altemative was evaluated in terms of the evaluation criteria required by the NCP. The nine criteria are categorized into one of three groups: threshold criteria, primary balancing criteria, and modifying criteria (Table 4). The altemative selected for each site must satisfy the threshold criteria, which are of primary importance. The primary balancing criteria were used to weigh the major tradeoffs among the altematives, and the modifying criteria were considered in light of the public comments on the Proposed Plan.

10.1 OveraU Protection of Human Health and the Environment

The "Maintenance of Existing Cover with LUCs, Site Maintenance, and Monitoring" action (Altemative 2) does, and "No Action" (Altemative 1) does not, prevent future residential land usage and mitigate the potential for exposure to subsurface materials that potentially contain hazardous constituents. With the exception of a small arsenic hotspot, the ecological risk assessment identified no unacceptable current or fiiture ecological risks. Altemative 2 would include long-term monitoring of groundwater, surface water and sediment to verify that constituents posing unacceptable risk have not been released to the environment. Altemative 1 would provide no such monitoring.

Since Altemative 1 does not meet this threshold criterion it is not evaluated below.


Table 4. Remedial Alternative Evaluation Criteria

Threshold Criteria:

•

•

Overall Protection of Human Health and the Environment refers to whether a remedy provides adequate protection against harmful effects. It calls for consideration of how human health or environmental risks are eliminated, reduced, or controlled through treatment, engineering controls, or institutional controls.

Compliance with Applicable or Relevant and Appropriate Requirements addresses whether a remedy meets all the applicable or relevant and appropriate requirements of federal and state environmental statutes.

Primary Balancing Criteria:

• Long-Term Effectiveness and Permanence refers to the magnitude of residual risk and the ability of a remedy to maintain reliable protection of human health and the environment after cleanup goals have been met.

• Reduction of Toxicity, Mobility, or Volume through Treatment refers to the effectiveness of the treatment technologies in reducing the toxicity, mobility, or volume of contaminants.

• Short-Term Effectiveness refers to the speed with which the remedy achieves protection and to the remedy's potential during constmction and implementation to have adverse effects on human health and the environment.

• Implementability refers to the technical and administrative feasibility of a remedy, including the availability of required materials and services.

• Cost includes capital expenditures and operation and maintenance costs.

Modifying Criteria:

• State Acceptance indicates whether the state concurs with, opposes, or has no comment on the preferred altemative based on its review of the RI/FS Reports, Proposed Plan, and public comments.

• Community Acceptance is documented in the ROD following consideration of public comments on the Proposed Plan.


10.2 Compliance with Applicable or Relevant and Appropriate Requirements

No chemical-specific ARARs are associated with Altemative 2. Altemative 2 would comply with all location-specific and action-specific ARARs. The State of Maryland has granted a variance to the landfill closure requirements of COMAR 26.04.07.21, as provided for by COMAR 26.04.07.26 (Attachment A).

10.3 Long-Term Effectiveness and Permanence

Altemative 2 would provide long-term effectiveness in protecting human health. LUCs require ongoing enforcement to remain effective.

10.4 Reduction of Toxicity, Mobility, or Volume through Treatment

Altemative 2 does not provide for reduction of toxicity mobility or volume through treatment because no wastes or contaminated media were identified that required treatment.

10.5 Short-Term Effectiveness

Altemative 2 does not involve constmction activities that endanger public communities or remedial workers, or adversely impact the environment. The RAOs would be achieved quickly upon implementation of LUCs.

10.6 Implementability

Altemative 2 does not depend on difficult to obtain equipment, services or technical specialists; therefore it is technically and administratively feasible.

10.7 Cost

The estimated cost for Altemative 2 is $1,349,000.

10.8 State Acceptance

State representatives have reviewed the altematives in the Proposed Plan for remedial action at 0U2B. Based on a thorough review of the remedial response altematives and public comments, MDE concurs with Altemative 2.

10.9 Community Acceptance

A summary transcript of the Public Meeting held on November 24, 2009, is available in the Administrative Record. Responses to written comments received from the community are presented in Part 3 of this document.

10.10 Summary of Comparative Analysis of Altematives

Altemative 2 will effectively control potential risk of exposure as a stand-alone response.


11 PRINCIPAL THREAT WASTES

Principal threat wastes are those source materials considered to be highly toxic or highly mobile that generally cannot be reliably contained, or would present a significant risk to human health or the environment should exposure occur. Materials remaining at OU 2B would not constitute a principal threat waste.

12 SELECTED REMEDY

12.1 Description of the Selected Remedy

The Selected Remedy is Altemative 2: Maintenance of Existing Cover with LUCs, Site Maintenance, and Monitoring. The Selected Remedy also includes Five-Year Reviews. The detailed approach and methodology will be specified in the RD.

> Land-Use Controls: LUCs will be implemented at the Bush River Study Area to prevent site activities that would result in unacceptable exposure. This area-wide LUC will prevent family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use within OU 2B and the remainder of the BRSA. An LUC for the Chemical Disposal Area and 30* Stieet Landfill will restrict excavation and other activities within OU 2B that could result in exposure of receptors to subsurface materials that potentially contain hazardous constituents. The LUC would include signs to wam that excavation without prior approval is not permitted. This LUC will also prevent disturbance of the existing shoreline stabilization stmctures, thereby ensuring effectiveness into the future. The extent of the BRSA within which residential land use will be restricted is identified in Figure 7. The OU 2B area within which excavation will be restricted is shown in Figure 8.

> Site Monitoring and Maintenance: Monitoring of site conditions will verify that the existing cover material at the 30* Street Landfill remains in place and protective of human health and the environment and that the shoreline erosion control measures remain in place, with maintenance being performed as necessary. The long-term maintenance together with long-term enforcement of LUCs will protect human health and the environment into the future; with LTM of groundwater, surface water and sediment providing verification that constituents posing unacceptable risk have not been released to the environment.

> Five-Year Reviews: LTM and CERCLA 121(c) five-year reviews will be conducted to ensure the long-term effectiveness of the remedial response, including LUCs. Five-year reviews will be conducted in accordance with OSWER Directives 9355.7-03B-P and 9234.2-25, or their most current revision or replacement.

Maintenance of the existing shoreline stabilization stmcture will include erosion control measures in areas adjacent to the stmcture. The two areas most subject to erosion are a small barren area in the southeast comer of the Chemical Disposal Site and the drainage swale through the Chemical Disposal Site. Preventive maintenance will involve

UntwrsalTrafisverse Morcator Proiecflon - Zone 18. Geodeflc Datum: Momi Aineflcan 1993 WGSa4 e m s o M . Measured m Suvay Feel

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1200 900 600 300 0 600 1200 2400

GRAPHICAL SCALE IN FEET (r-1200T

TITLE: 1:14400

L E G E N D

Water

Road

Tidal Wetland

Non-tidal Wetland

Restricted Residential Land Use

Leading Ihe world to better performance 500 Edgewood Rd, Suite 110 (410) 676-8835 Edgewood. MD 21040 www.gpworidwide.com

EXTENT OF RESTRICTED RESIDENTIAL LAND USE

IN BUSH RIVER STUDY AREA CARTOGRAPHER:

B. XIYCE

APPROVED BY:

J.HARRIS

DATE:

02-18-10

FIGURE:

l:\Edgewood Graphics\aEOCRAPHICS\Bush R i v e r \ K i a g s Creek \PPD\Land Use Rest r ic t ions .dgn

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I I

UnlveredTransverse Mercator Prolacnon - Zone IB. Qeodeflc Datutn; Nortti Amwlcar 1963 WQSa4 E l p s o M . Measrjred Ir Survey Feet

ISI

150 100

GRAPHICAL SCALE IN FEET ( I ' - I S O

300

1:1800

L E G E N D Paved Road i - ^ i WeMand

Water Stream

Proposed

Excavation Restriction

Leading the w o r l d to b e t t e r pe r fo rmance

500 Edgewood Road. Suite 110 (410) 676-8835 Edgewood. MD 21040 www.gpwor1dwide.com

TITLE:

EXTENT OF EXCAVATION RESTRICTION WITHIN OPERABLE UNIT 2B

CARTOGRAPHER:

B. JOYCE

APPROVED BY:

J.HARRIS

DATE:

02-18-10

FIGURE:

8

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placement of stone in the lower portion of the drainage swale, and stabilization of the barren area by placement of topsoil with subsequent seeding to establish vegetation. The stabilized drainage swale will be maintained as part of the shoreline stabilization stmcture and will also be protected by the LUC that prohibits disturbance of that structure.

The RD will be submitted consistent with the RD schedule provisions of the FFA and will include the Site Maintenance and Monitoring Plan, the LTM Plan, and the details of LUC implementation and maintenance (including periodic inspections).

12.2 LUC Remedial Design

The RD will include an LUC component describing the details of LUC implementation and maintenance, including periodic inspections. The LUCs will include implementation through the APG Master Planning system with GIS support.

The U.S. Army will be responsible for implementation, maintenance, periodic inspection, reporting on and enforcement of LUCs in accordance with the RD and this ROD. Although the U.S. Army may transfer these responsibilities to another party by contract, property transfer agreement, or through other means, the Army will remain responsible for: ^

> conducting CERCLA Section 121 (c) five year reviews;

> notifying USEPA and MDE and/or local government representatives of any known LUC deficiencies or violations;

> obtaining access to the property to conduct periodic inspections and any necessary response; and

> ensuring that the LUC objectives are met to protect the integrity of the selected remedy.

As set forth in the RD, the U.S. Army will not modify or terminate LUCs or implementing actions without prior approval of USEPA, after conferring with MDE. The U.S. Army will seek prior concurrence before taking an action that would dismpt the effectiveness of the LUCs.

If the U.S. Army tiansfers property in the areas addressed by this ROD, the U.S. Army will ensure that the restrictions on site activities are included in the deed to the property recorded in the local property records and that notification of the restrictions in the deed is filed with the appropriate agencies, so that current and future property owners will be aware of these restrictions. Specific deed restriction language and the appropriate agencies will be identified in the approved RD. While the U.S. Army maintains ultimate responsibility for LUC enforcement, the Army may require the transferee or lessee in cooperation with other stakeholders to assume responsibility for LUC implementation actions. Third-party LUC responsibility will be incorporated into pertinent contractual, property and remedial documentation, such as a purchase agreement, deed, lease and RD addendum.


To the extent permitted by law, a transfer deed shall require the LUCs imposed as part of a CERCLA remedy to mn with the land and bind all property owners and users. If the U.S. Army intends to transfer ownership of any site, the Army may, if federal and/or state law allows, upon transfer of fee title grant the state an environmental covenant or easement that would allow the state to enforce LUC terms and conditions against the transferee(s), as well as subsequent property owner(s) or user(s) or their contractors, tenants, lessees or other parties. This covenant will be incorporated by reference in the transfer deed and will mn with the land in accordance with state realty law. This state enforcement right would supplement, not replace, the U.S. Army's right and responsibility to enforce the LUCs.

12.3 Summary of the Rationale for the Selected Remedy

The Selected Remedy meets the threshold criteria, provides the best balance of tradeoffs with regard to the primary balancing criteria as compared to the other altematives and satisfies the modifying criteria. It was selected to satisfy the following statutory requirements of CERCLA Section 121(b) to:

> beprotectiveof human health and the environment;

> comply with ARARs, unless waived;

> be cost-effective;

> utilize permanent solutions and altemative treatment technologies or resource recovery technologies to the maximum extent practicable; and

> satisfy the preference for treatment as a principle element when justified.

Except for the arsenic hotspot, the risk assessment identified no unacceptable risk to industrial workers or ecological communities. There are no COCs and no media of concem. Therefore, no RGs have been developed for protection of workers or the environment. The disposed waste within the 30* Street Landfill has not been fully characterized. There is no need to develop RGs for constituents that possibly exist in waste, because the presumptive containment remedy will prevent exposure to constituents in waste.

Since there are no RGs or chemical-specific ARARs at OU 2B, the Selected Remedy does not employ tieatment to reduce toxicity, mobility or volume of hazardous substances, pollutants, or contaminants and, therefore, does not satisfy the statutory preference for remedies that employ treatment as a principal element. The only potential risk is posed by inadvertent excavation/exposure of subsurface waste and, therefore, LUCs to prevent site activities that would result in unacceptable exposure will effectively protect human health and the environment.

The 30'*' Stieet Landfill was created by landfilling into a tidal marsh. The landfilled waste lies beneath the water table. The existing cover soil is uncontaminated and does not contain constituents at concentiations that pose risk to either human health or the environment. Because of these factors, a low-permeability cap or additional cover soil

Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Grotmd, Maryland Page 44

would not protect human health or the environment to a greater extent than the existing cover, provided that the existing cover is maintained.

Table 5 lists the ARARs for the Selected Remedy. The existing soil and natural vegetation cover does not meet the State of Maryland regulation for landfill closure. The U.S. Army submitted an application for a variance to the requirements of COMAR 26.04.07.21 which relate to closure of sanitary, mbble and industrial waste landfills, including specifications for low permeability closure caps. The variance was granted by the MDE (Attachment A) in accordance with COMAR 26.04.07.26 because the existing cover for the 30* Street Landfill conserves and protects public health and environment to at least the same extent as would be obtained by a low permeability cap at this site.

Maintenance of the existing shoreline stabilization stmcture includes erosion control measures in areas adjacent to the stmcture. The two areas most subject to erosion are a small barren area in the southeast comer of the Chemical Disposal Area and the drainage swale through the Chemical Disposal Site, through which a large volume of water flows when floodwaters recede after a hurricane storm surge. Preventive maintenance will involve placement of stone in the lower portion of the drainage swale, and stabilization of the barren area by either placement of stone or by placement of topsoil with subsequent seeding to establish vegetation. These same two areas have been of regulatory concem because of the barren nature of the one site and because there is an arsenic hot spot in the lower portion of the drainage swale. While the risk associated with these two small areas may not be sufficient to trigger remedial action under CERCLA, the preventive maintenance to control erosion will also reduce exposure and address regulatory concem. The stabilized drainage swale will be maintained as part of the shoreline stabilization stmcture, and will also be protected by the LUC that prohibits disturbance of that stmcture.

The Selected Remedy and associated remedial activities do not pose a risk to remedial workers. Trained personnel following proper health and safety procedures will conduct all intmsive activities (such as well installation, if needed). All RAOs will be achieved upon implementation.

The Selected Remedy will result in hazardous substances, pollutants or contaminants remaining on site at levels that do not allow for unlimited use and unrestricted exposure. Therefore, LUCs will be implemented to prevent site activities that would result in unacceptable exposure. These sites will be included in the periodic CERCLA Section 121 (c) remedy reviews of the Edgewood Area's NPL sites.

Re^Wd of Decision Bush River Study Area Operable Unit 2B Aberdeen Proving Ground, Maryland

May 2010 Page 45

Table 5. Applicable or Relevant and Appropriate Requirements

CODE REQUIREME^T

SUBSTANTIVE REQUIREMENTS

.ARAR TYPE CONSIDERED

CODE OF MARYLAND REGULATIONS (COMAR) IITLE 26. DEPARIMEN I OF IHE ENVIRONMEN I

Subtitle 4 - Regulation of Water Supply, Sewage Disposal and Solid Waste

Chapter 04 - Well Construction

26.04.04.07 Construction Standards Establishes requirements for sanitary protection during well construction, water used for drilling, well design, construction materials and construction procedures.

26.04.04.10 Well Owners' Responsibilities Requires well owners to maintain wells so that groundwater is protected and wells can be identified.

26.04.04.11 Abandonment Standards

Chapter 07 - Solid Waste Management

26.04.07.21 Sanitary Landfill - Closure

26.04.07.22 Sanitary Landfills - Post-Closure Monitoring and Maintenance

26.04.07.26 Variances

Establishes standards for abandonment of wells.

Establishes requirements for closure of sanitary, rubble and industrial waste landfills, including specifications for the closure cap.

Establishes requirements for post-closure inspections and maintenance for landfills.

Establishes the framework for obtaining variances to the Requirements of the solid waste management regulations, including closure cap requirements.

Action-Specific

Action-Specific

Action-Specific

Action-Specific

Action-Specific

Action-Specific

Applicable for any new or replacement monitoring wells constructed in the future.

Applicable for existing monitoring wells and any new or replacement wells constructed in the future.

Applicable for existing monitoring wells and any new or replacement wells constructed in the future.

Relevant & Appropriate

Relevant & Appropriate for future O&M activities.

Relevant & Appropriate Variance has been granted for SO'̂ Street Landfill.

CODE OF MARYLAND REG ULATIONS (COMAR)

TITLE 27. CRITICAL AREA COMMISSION FOR THE CHESAPEAKE AND ATLANTIC COASTAL BAYS

Chesapeake Bay Critical Area Protection Program

Defines critical areas and critical area buffer zones. Establishes the "critical area" as all lands within 1,000 feet of Tidal waters or tidal wetlands. Defines the "critical area buffer" as that land within 100 ft of tidal waters or tidal wetlands. Requires that tree and natural vegetation clearing be minimized within "critical areas", and that when clearing is necessary, mitigation by planting trees in a Chesapeake Bay Critical Area be accomplished at ratios ranging from 1;1 to 3:1.

Establishes Critical Area Buffers 100 ft in width along tidal shorelines in which construction is not permitted without a variance.

Clearing of Natural Vegetation, Trees and Forest

Habitat Protection Areas

Location-Specific Relevant & Appropriate for O&M activities.

Location-Specific Relevant & Appropriate for O&M activities.


Final May 2010

Page 46

12.4 Summary of Estimated Remedy Costs

The information in the cost estimate summary is based on the best available information regarding the anticipated scope of the remedial response. Changes in the cost elements are likely to occur as a result of new information and data collected during RD and post-remediation verification. This is an engineering cost estimate that is expected to be within -30 to +50 percent of the actiial project cost (USEPA, 1999; USEPA, 2000). The estimated cost for each site includes total capital cost, annual O&M costs and present worth over a 30-year period. The detailed costs are provided in Table 6, and summarized below:

Cost Summarv

Capital Cost O&M / LTM Costs Total Present Worth Costs O&M Time Frame Time to Achieve RAOs

$86,000 $1,263,000 $1,349,000

30 Years 6 Months

12.5 Expected Outcomes of Selected Remedy

Maintenance of the Existing Cover with LUCs, Site Maintenance, and Monitoring remedy will effectively control potential risk of exposure upon implementation.

12.6 Performance Standards for the Selected Remedy

The remedial performance standards are:

^ Restrictions will be placed in the APG GIS and Real Property Master Plan to prevent family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use within OU 2B and the remainder of the BRSA (See Figure 7).

^ Restrictions will be placed in the APG GIS and Real Property Master Plan to restrict excavation and other activities within OU 2B that could result in exposure of receptors to subsurface materials that potentially contain hazardous constituents and to prevent disturbance of the existing shoreline stabilization stmctures (See Figure 8).

> Maintain the existing cover material and vegetation at the 30th Stieet Landfill and the BRSA shoreline erosion control measures in order to be protective of human health and the environment.

Item

Studv/Desiqn/Capital Costs

LUC Implementation Remedial Design LUC Implementation Waming Signs

Hot Spot Remediation

Table 6 Detailed Costs for the Selected Remedy

Events/ Quantity Years Starting per Year

Cost

Units Unit Cost Event/Year Cost

1 1 1 1

2009 2009 2009 2009

1 1 1 1

ea ea ea ea

Total Capital Costs (Rounded)

O & M Costs Remedy Reviews & Site Closeout

Five Year Reviews Site Closeout Land Use Control Enforcement Site Inspections (annual) Long-Term Monitoring

Total O&M and Monitoring Costs (Rounded)

Events/ Years Starting

6 2009 1 2009

30 2009 30 2009 30 2009

Base Year 2009

1 years ea

1 years 1 years 1 years

s o per Discounted •g

TOTAL

Discount Rate for Present Value Calculations [Appendix C of OMB Circular No. A-94] (30-Year)

$26,455 $39,890 $10,000 $10,000

$26,455 $39,890 $10,000 $10,000

Cost per

Event/Year

$21,316 $27,344 $12,676

$8,500 $34,053

[

$26,455 $39,890 $10,000 $10,000

$86,000

Discounted Cost

$93,100 $27,344

$262,143 $175,783 $704,226

$1,263,000

$1,349,0001

2.8%

2.0%

3.0%

0.7%

0.7%

6.9% 2.0%

19.4%

13.0%

52.2%


13 STATUTORY DETERMINATIONS

13.1 Protection of Human Health and the Environment

Potential exists for risk to human health and the envirormient if no remedial action is undertaken. This remedial response meets the requirements of CERCLA Section 121 and, to the extent practicable, the NCP. The Selected Remedy is protective of human health and the environment.

The Selected Remedy and associated remedial activities do not pose a risk to remedial workers. Trained persormel following proper health and safety procedures will conduct all intmsive activities (such as well installation, if needed).

All RAOs will be achieved upon implementation of the Selected Remedy.

13.2 Compliance with Applicable or Relevant and Appropriate Requirements

The following are ARARs to the selected Response Action for OU 2B (Table 5):

• Code of Maryland Regulations (COMAR): Title 26;

> Subtitle 4 - Regulation of Water Supply, Sewage Disposal and Solid Waste

• Chapter 04 - Well Consti-uction

• 26.04.04.07 Constmction Standards

• 26.04.04.10 Well Owners' Responsibilities

• 26.04.04.11 Abandonment Standards

• Chapter 07 - Solid Waste Management

• 26.04.07.21 Sanitary Landfill-Closure

• 26.04.07.22 Sanitary Landfill - Post-Closure Monitoring and Maintenance

• 26.04.07.26 Variances

• Code of Maryland Regulations (COMAR): Title 27;

> Chesapeake Bay Critical Area Protection Program

• Clearing of Natural Vegetation, Trees and Forest

• Habitat Protection Areas

There are no ARARs associated with LUCs. Site maintenance and monitoring activities will be accomplished in a manner that complies with CFR and COMAR requirements for environmental protection, solid waste management and well constmction as appropriate. A variance to the requirements of COMAR 26.04.07.21 which relate to closure of sanitary, mbble and industrial waste landfills, including specifications for low permeability closure caps has been obtained in accordance with COMAR 26.04.07.26.

13.3 Cost-Effectiveness

A containment altemative for the 30"" Street Landfill is consistent with the presumptive


remedy for landfills. The Selected Remedy is at least as effective in protecting human health and the environment as a capping remedy would be, and does not destroy wetlands as would constmction of a more costly, engineered cap.

A risk management decision was made to tailor CERCLA response to the most reasonably anticipated land use - military/industrial - and proceed with LUCs to prevent unlimited land use and unrestricted exposure rather than delay protection of human health in order to conduct additional and costly investigations that would not likely alter the response outcome.

13.4 Utilization of Permanent Solutions and Altemative Treatment Technologies to the Maximum Extent Practicable

The Selected Remedy is a permanent solution, albeit requiring ongoing O&M and LTM. There is insufficient data on the subsurface material having the potential to pose risk to assess the efficacy of treatment technologies. A risk management decision was made to proceed with LUCs, site maintenance and monitoring rather than delay protection of human health in order to conduct additional and costly investigations that would not likely alter the response outcome.

13.5 Preference for Treatment as a Principal Element

Since no RGs or chemical-specific ARARs apply to OU 2B, the Selected Remedy does not employ treatment to reduce toxicity, mobility or volume of hazardous substances, pollutants or contaminants and, therefore, does not satisly the statutory preference for remedies that employ treatment as a principal element. The only potential risk is posed by inadvertent excavation/exposure of subsurface waste and, therefore, LUCs to prevent site activities that would result in unacceptable exposure, site maintenance and monitoring will effectively protect human health and the environment.

13.6 CERCLA 121(c) Five-Year Review Requirement

Hazardous substances, pollutants, or contaminants will remain on site at levels that do not allow for unlimited use and unrestricted exposure. Therefore, five-year reviews will be performed as required by CERCLA and the NCP. Five-year reviews will be conducted in accordance with OSWER Directives 9355.7-03B-P and 9234.2-25, or their most current revision or replacement.

14 DOCUMENTATION OF SIGNIFICANT CHANGES

No significant changes were made to the Proposed Remedial Action Plan since it was noticed to the public.



Record of Decision Final Bush River Study Area Operable Unit 2B May 2010 Aberdeen Proving Ground, Maryland , Page 51

PART 3: RESPONSIVENESS SUMMARY

The purpose of the Responsiveness Summary is to provide a summary of the public's comments, concems and questions about the Edgewood Area Proposed Plan for Remedial Action at BRSA OU 2B, and the Army's responses to these concems.

APG held a public meeting on November 24, 2009 to formally present the Proposed Plan and response actions and to answer questions and receive comments. The summary tianscript of this meeting is part of the Administiative Record for the Edgewood Area. During the public comment period, APG also received written comments. All comments and concems summarized below have been considered by the Army and USEPA in selecting the response actions for BRSA OU 2B.

1 OVERVIEW

At the time of the public comment period, the U.S. Army and USEPA had endorsed the Existing Cover with LUCs, Site Maintenance and Monitoring to protect human health and the environment.

Based on a thorough review of the remedial response altematives and public comments, MDE concurs with the Selected Remedy.

2 BACKGROUND ON COMMUNITY INVOLVEMENT

APG has maintained an active public involvement and information program for the IRP since the early 1990s. APG's specific community relations activities for BRSA OU 2B were as follow:

• APG began discussing altematives for OU 2B with the RAB in July 2005. Other RAB meetings where APG presented information on altematives for BRSA and OU 2B included June 2006, July 2007, May 2008, and June 2009.

" APG released the OU 2B Proposed Plan for public comment on November 4, 2009. Copies were available to the public through APG's administiative record locations at the Edgewood and Aberdeen branches of Harford County Library and Miller Library at Washington College in Kent County.

• A 45-day public comment period on the Proposed Plan ran fi"om November 4 to December 18,2009.

• APG prepared a release announcing the availability of the Proposed Plan, the dates of the public comment period, and the date and time of the public meeting. APG placed newspaper advertisements announcing the public comment period and meeting in The Aegis, The Avenue News, The Cecil Whig, East County Times and Kent County News. A sample newspaper advertisement announcing the public comment period and the public meeting is provided on Figure 9.

U.S. ARMY INVITES PUBLIC COMMENT ON PROPOSED PLAN FOR THE

KINGS CREEK CHEMICAL DISPOSAL SITE AND 30^" STREET LANDFILL

The U.S. Army at Aberdeen Proving Ground (APG) invites the public to comment on its Proposed Plan for the Kings Creeic Chemical Disposal Site and 30''' Street Landfill in the Bush River Study Area.

FACT SHEET APG has prepared a fact sheet on the

proposed plan which includes a comment form that can be retumed to APG.

If you are not on APG's mailing list, you can request a copy of the fact sheet by calling APG's 24-hour Environmental Information Line at (410) 272-8842 or (800) APG-9998.

PUBLIC MEETING APG invites the public to attend a meeting on:

DATE: Tuesday, November 24, 2009

TIME: 6:30 p.m. - informal poster/ information session

7:15 p.m. - presentation

PLACE: Vitali's Restaurant and Banquets 1709 Edgewood Road Edgewood, MD 21040

The meeting location is wheelchair accessible, and an interpreter for the hearing impaired is available with 72-hours advance notice (call 800-APG-9998).

WRITTEN COMMENTS The 45-day public comment period on

the proposed action extends from November 4 to December 18, 2009. Written comments, postmarked by December 18, 2009, should be sent to: Mr. Ken Stachiw Directorate of Public Works ATTN: IMNE-APG-PWE Bldg. E57717 Magnolia Road Aberdeen Proving Ground, MD 21010; or

Mr. Frank Vavra U.S. Environmental Protection Agency,

Region III, 1650 Arch Street (3HS13) Philadelphia, PA 19103-2029; or Dr. Elisabeth Green Maryland Department of the Environment Federal Facilities Division Haz2irdous Waste Program 1800 Washington Boulevard, Suite 645 Baltimore, MD 21230-1719

PROPOSED ACTION APG has prepared a Proposal Plan to address surface media (i.e., soil, sediment and surface

water) within the Bush River Study Area Operable Unit (OU) 2B - Kings Creek Chemical Disposal Site and 30''' Street Landfill. At the location of the sites, constituents in groundwater do not pose unacceptable risk, and a response action addressing groundwater is not necessary. Monitoring of the sites will verify that future releases do not impact groundwater.

ALTERNATIVES EVALUATED Alternative A: No Action. The National Oil and Hazardous Substances Pollution Contingency Plan (NCP) requires consideration of no action as a baseline with which to compare other altematives. Under this altematives, land use controls (LUCs) would not be implemented and existing institutional controls, such as APG standard operating procedures, may not continue. Cost: $0 Alternative B: Existing Cover With LUCs, Site Maintenance and Monitoring. This altemative involves containment of the landfilled waste, which is a presumptive remedy for landfills. The existing landfill cover would be maintained, preventing direct exposure to underlying waste, with natural vegetation and the shoreline stabilization structure preventing soil erosion. A LUC would prevent unplanned future family housing, elementary and secondary schools, child care facilities, playgrounds, and other residential land use within 0U2B and the remainder of the Bush River Study Area. A LUC would also restrict excavation and other activities within 0U2B that could result in exposure of receptors to subsurface materials that potentially contain hazardous constituents. The LUC would include signs to wam that excavation without prior approval is not permitted. This LUC would also prevent disturbance of the existing shoreline stabilization structures, thereby ensuring their effectiveness into the future. Monitoring of site conditions would verify that the shoreline erosion control measures remain effective and that the existing soil and natural vegetation cover at the 30"" Street Landfill remains in place and protective pf human health and the environment. Monitoring of groundwater, surface water, and sediment would also be conducted to detect releases to Kings Creek. Cost: $1,349,000

Based on analysis of the alternatives, APG prefers Alternative B, Existing Cover with LUCs, Site Maintenance and Monitoring.

The preferred altemative may be modified or new alternatives may be developed based on public input. The final altematives selected will be documented in a Record of Decision that summarizes the decision-making process. APG will summarize and respond to comments received during the comment period as part of the Record of Decision. Copies of the Feasibility Study and the Proposed Plan are available for review at the APG information repositories. The repositories are located at the Edgewood (410-612-1600) and Aberdeen (410-273-5608) branches of the Harford County Library and Miller Library at Washington College in Kent County (410-778-7292).


• APG prepared and published a fact sheet on the Proposed Plan including information on the public meeting. APG mailed copies of this fact sheet to more than 2,600 citizens and elected officials on its IRP mailing list. The fact sheet included a form, for citizens to use to send APG their comments.

• On November 24, 2009, APG held a public meeting at the Vitali's Restaurant and Banquets in Edgewood, Maryland. Representatives of the Army, USEPA, and MDE were present at the meeting. APG representatives presented information on the sites and on the proposed response actions.

3 SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC COMMENT PERIOD AND AGENCY RESPONSES

Comments raised during the public comment period are summarized below. The comments are categorized by source.

COMMENTS FROM OUESTIONNAIRE FNCLUDED WITH FACT SHEET

As part of its fact sheet on the Proposed Plan, APG included a questiormaire that residents could return with their comments. APG received two forms; only one form had a comment. The altematives preferred by individuals returning comment forms were:

1 Altemative A (1) - No Action 1 Altemative B (2) - Existing Cover with LUCs, Site Maintenance, and Monitoring

Written comments included on the forms are summarized below.

Comment No. 1: Why isn't there an Altemative C that would take more aggressive action? B is plainly safer but hardly justifies the exorbitant cost! Why should maintenance and monitoring cost over a million dollars? B seems little more than A? Please provide rationale why you are charging the taxpayers these immense costs to simply impose rules and monitoring.

Response No. 1:

A third altemative (Low Permeability Cap with Land Use Controls, Site Maintenance, and Monitoring) was considered during the initial screening phase of the Feasibility Study. This option was eliminated prior to the development of detailed altematives for several reasons. From a construction and long-term maintenance standpoint, a low permeability cap would be more problematic at the 30"* Street Landfill than at a typical upland sanitary landfill. The landfilling was into a marsh, with a limited amount of compaction, and the cover contains a substantial amount of organic matter. It is possible that there would be substantial settiing following construction, which could damage/compromise the low permeability layers of the cap. Construction of the low permeability cap would also result in the destmction of more than an acre of wetland, requiring wetlands permitting and mitigation. This type of action cannot be justified for this site when hazardous constituent releases have not been observed fiôm the landfill to groundwater, surface water, sediment, or surface soil. Further, the primary advantage to a


low permeability cap is the prevention of leaching. Most of the waste at this site is present beneath the water table; therefore, a low permeability cap cannot prevent water fi-om infiltrating the subsurface materials. Because the low permeability cap was no more effective than the existing cover material in protecting human health and the environment, at a substantially higher cost, Altemative 3 was not carried through to the Proposed Plan. '

The cost associated with the preferred altemative (Maintenance of Existing Cover with Land Use Controls, Site Maintenance, and Monitoring) is estimated for a 30-year period. The majority of the cost (85%) is associated with maintenance of the existing shoreline stabilization stmcture and the monitoring of groundwater, surface water, and sediment necessary to verify the protectiveness of the remedy.

COMMENTS FROM PUBLIC MEETING

No written comments were submitted at the public meeting and no oral comments were made.


PART 4: REFERENCES

General Physics Corporation (GP). 2002a. Focused Feasibility Study Data Report,

Operable Unit 2 - Source Area Sites, Southern Bush River, Bush River Study

Area. Prepared by General Physics Corporation for Directorate of Safety, Health

and Environment, Aberdeen Proving Ground, Maryland.

. 2002b. Southern Bush River Remedial Investigation Report, Bush River Study

Area, Aberdeen Proving Ground, Maryland. Prepared by General Physics

Corporation for Directorate of Safety, Health and Environment, Aberdeen

Proving Ground, Maryland.

. 2003. Northern Bush River Remedial Investigation Report, Bush River Study

Area, Aberdeen Proving Ground, Maryland. Prepared by General Physics

Corporation for Directorate of Safety, Health and Environment, Aberdeen

Proving Ground, Maryland.

. 2008. Supplemental Remedial Investigation Report, OU2B - Kings Creek

Chemical Disposal Site and 3(f Street Landfill, Bush River Study Area, Aberdeen

Proving Ground, Maryland. Prepared by General Physics Corporation for

Directorate of Safety, Health and Environment, Aberdeen Proving Ground,

Maryland.

. 2009. Feasibility Study, Kings Creek Chemical Disposal Site and 3(f Street

Landfdl (Operable Unit 2B), Bush River Study Area, Aberdeen Proving Ground,

Maryland. Prepared by General Physics Corporation for Directorate of Public

Works, Aberdeen Proving Ground, Maryland.

ICF Kaiser Engineers (ICF). 1997. Baseline Risk Assessment for Southern Bush River

Area, Aberdeen Proving Ground, Maryland. Abingdon, MD. Prepared for the

Directorate of Safety, Health and Environment, Aberdeen Proving Ground,

Maryland.

U.S. Army Environmental Center (USAEC). 1998. U.S. Army Restoration Advisory

Board and Technical Assistance for Public Participation Guidance. April 1998.

U.S. Army Environmental Hygiene Agency (USAEHA). 1989. Resource Conservation

and Recovery Act Facility Assessment for the Edgewood Area of Aberdeen


Proving Ground, Maryland. Report No. 39-26-0490-90. Aberdeen Proving

Ground, MD: U.S. Department of the Army.

U.S. Army Toxic and Hazardous Materials Agency (USATHAMA). 1983.

Environmental Survey of the Edgewood Area of Aberdeen Proving Ground. U.S.

Army Toxic and Hazardous Materials Agency. Aberdeen Proving Ground, MD.

U.S. Environmental Protection Agency (USEPA). 1999. A Guide to Preparing Superfund

Proposed Plans, Records of Decision, and Other Remedy Selection Decision

Documents. EPA 540-R-98-031.

. 2000. A Guide to Developing and Documenting Cost Estimates During the

Feasibility Study. EPA 540-R-00-002.

USEPA Region III, APG, and U.S. Department of the Army. 1990. Federal Facility

Agreement under CERCLA Section 120, Aberdeen Proving Ground, Maryland.

Administrative Docket Number III-FCA-CERC-004. USEPA Region III and U.S.

Department of the Army.

. 2099 Record of Decision, Cluster 3, Site 3, Old Bush River Road Dump,

Aberdeen Proving Ground, Maryland. USEPA Region III and U.S. Department of

the Army.

. 2005 Record of Decision, Remedial Action at the Cluster 3 Lead-Contaminated

Soil Area, Aberdeen Proving Ground, Maryland. USEPA Region III and U.S.

Department of the Army.


Attachment A

MDE Conditions of Variance: COMAR 26.04.07

0AD E MARYLAND DEPARTMENT OF THE ENVIRONMENT 1800 Washington Boulevard • Baltimore MD 21230 410-537-3000 • 1-800-633-6101

Martin O'Malley Shari T.Wilson Governor Secretary

Anthony G. Brown Robert M. Summers, Ph.D. Lieutenant Governor Deputy Secretary

May 22, 2009

Mr. Rurik Loder Directorate of Safety, Health and Environment Building E5771 Aberdeen Proving Ground, MD 21010

RE: Final Remedy for 30"̂ Street Landfill, Bush River Study Area, Request for Variance, letter datedFebruary 12, 2009 .

Dear Mr. Loder:

m The Federal Facilities Division (FFD) of the Maryland Department of the Environment's (MDE)

azardous Waste Program has completed its review of the referenced communication. This letter describes e Army's proposed final remedy for the 30"̂ Stieet Landfill in the Bush River Study Area, which is a

former disposal area. The proposed final remedy includes land use controls, site maintenance, and monitoring. The Army is conducting this action in compliance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

The proposed remedy requires a variance to the State's landfill closure regulations for landfills, which are Applicable or Relevant and Appropriate Requirements under CERCLA. The FFD in consultation with MDE's Solid Waste Program has reviewed the proposed action and the requested variance. If maintained and monitored adequately, the proposed remedy should be as protective as the State's landfill closure regulations, which are stated in Code of Maryland Regulations (COMAR) 26.04.07.21. Consequently, in accordance with the variance provision contained in COMAR 26.04.07.26, the Army's request for a variance will be considered favorably if the following conditions are adequately addressed in the Record of Decision for this site:

i. Land use controls ensure that future land use doiss not include residential use and that excavation and other activities that may result in contact with subsurface materials are restricted.

ii. Long-term maintenance activities protect the integrity of existing cover material and shoreline erosion control measures with monitoring adequate to comply with Solid Waste regulations.

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Page Two Mr. Rurik Loder

iii. Long-term monitoring of ground water, surface water, and sediment will be conducted to • detect releases to Kings Creek. This monitoring program will be used to evaluate the

" adequacy of the remedy and the continued use of the variance provision contained in COMAR.

If you have ajny questions, please contact me at (410) 537-3346. ^

Sincerely,

Jf-*' Elisabeth Green, Ph.D. Remedial Project Manager Federal Facilities Division

EG:eg

cc: Mr. Frank Vavra Mr. Horacio Tablada Mr. Harold L. Dye, Jr.

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