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u.s. Army Garrison Aberdeen Proving Ground, Maryland

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Explanation of Significant Differences

Remedial Action

G-Street Salvage Yard

Canal Creek Study Area

Aberdeen Proving Ground, Maryland

Submitted by:

Directorate of Public Works, Environmental Management Division

U.S. Army Garrison, Aberdeen Proving Ground, Maryland

Final, June 2009

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Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page ii

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Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page iii

TABLE OF CONTENTS

Section Page

1. INTRODUCTION TO THE SITE AND STATEMENT OF PURPOSE ................. 1-1 1.1 STATEMENT OF PURPOSE ............................................................................. 1-1

2. SITE HISTORY, CONTAMINATION, AND SELECTED REMEDY ................... 2-1 2.1 SITE HISTORY AND CONTAMINATION ...................................................... 2-1

2.2 SELECTED REMEDY AS ORIGINALLY DESCRIBED IN THE ROD ......... 2-1

3. BASIS FOR DOCUMENT............................................................................................ 3-1 3.1 POST-ROD INVESTIGATIONS........................................................................ 3-1

3.1.1 Geophysical Investigations, December 2007 – February 2008 ............ 3-1 3.1.2 Anomaly Verification, February 2008.................................................. 3-3 3.1.3 Remedial Design Appendix F............................................................... 3-3

3.2 LEVEL A EXCAVATION ACTIVITIES, OCTOBER 2008 ............................. 3-4

3.3 CWM/UXO RISK ASSESSMENT FOR THE G-STREET SALVAGE YARD BURN RESIDUE DISPOSAL AREA .................................................... 3-5

4. DESCRIPTION OF SIGNIFICANT DIFFERENCES .............................................. 4-1 4.1 SCOPE ................................................................................................................. 4-1

4.2 PERFORMANCE................................................................................................ 4-1

4.3 COST ................................................................................................................... 4-2

4.4 EXPECTED OUTCOMES .................................................................................. 4-2

5. SUPPORT AGENCY COMMENTS............................................................................ 5-1 5.1 COMMENTS DURING DEVELOPMENT OF THE MODIFIED

APPROACH ........................................................................................................ 5-1

5.2 COMMENTS ON THE ESD............................................................................... 5-1

6. STATUTORY DETERMINATIONS .......................................................................... 6-1

7. PUBLIC PARTICIPATION COMPLIANCE ............................................................ 7-1

8. REFERENCES............................................................................................................... 8-1

9. AUTHORIZING SIGNATURES ................................................................................. 9-1

Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page iv

LIST OF TABLES

Title Page

Table 1 Direct Side-by-Side Comparison of Selected Remedy and Modifications ................. 4-3

LIST OF FIGURES

Title Page

Figure 1 BRDA in Accordance with the ROD vs. the ESD ................................................... 4-5

Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page v

LIST OF ACRONYMS

APG Aberdeen Proving Ground bgs below ground surface BRDA Burn Residue Disposal Area CAFS chemical agent filtration system CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CERCLIS CERCLA Information System COC chemical of concern CWM chemical warfare materiel DAAMS depot area air monitoring system ECBC Edgewood Chemical Biological Center EOD Explosive Ordnance Disposal EPA United States Environmental Protection Agency ESD Explanation of Significant Differences GPR Ground Penetrating Radar ICF ICF Kaiser IRP Installation Restoration Program LUC Land Use Control MDE Maryland Department of the Environment MEC munitions and explosives of concern NCP National Oil and Hazardous Substances Pollution Contingency Plan NOA notice of availability NPL National Priorities List OSHA Occupational Safety and Health Administration OU Operable Unit PPE personal protective equipment RAB Restoration Advisory Board RG remedial goal ROD Record of Decision SARA Superfund Amendments and Reauthorization Act TE Technical Escort USAGAPG U.S. Army Garrison Aberdeen Proving Ground UXO/CWM unexploded ordnance/chemical warfare material VCS vapor containment structure WWI World War I WWII World War II WESTON Weston Solutions, Inc.®

Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page vi


Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area June 2009 Aberdeen Proving Ground, Maryland Page 1-1

1. INTRODUCTION TO THE SITE AND STATEMENT OF PURPOSE

Aberdeen Proving Ground (APG) is a n,500-acre Army installation located on the western

shore of the upper Chesapeake Bay in southern Harford County and southeastern Baltimore

County, MD. 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 Joppa, Edgewood, and Abingdon. The Bush

River divides APG into two distinct areas: the Edgewood Area to the west, and the Aberdeen

Area to the east.

The G-Street Salvage Yard is located in the north-central portion of the Canal Creek Study Area,

approximately 2,000 feet from the installation boundary and adjacent to the Route 24 main gate

to the Edgewood Area of APG. The Salvage Yard is a triangle-shaped area of about 15 acres,

with approximate maximum dimensions of 1,200 feet nOlth to south by 1,000 feet east to west.

The Burn Residue Disposal Area (BRDA) is located in the southern portion of the G-Street

Salvage Yard site.

The United States Environmental Protection Agency (EPA) Superfund Site Identification

Number for APG-EA is MD 2210020036. The G-Street Salvage Yard will be listed in the

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)

Information System (CERCLIS) database under Operable Unit (OU) 14. The site owner and lead

agency is the Army, with EPA as the support agency and the Maryland Depattment of the

Environment (MOE) as the state regulatory agency.

A Record of Decision (ROD) for the Remedial Action at the G-Street Salvage Yard, Canal Creek

Study Area was signed by the Army and EPA in September 2007 (U.S. Army Garrison,

Aberdeen Proving Ground (USAGAPG), 2007).

1.1 STATEMENT OF PURPOSE

Post-ROD investigations conducted at the site (including geophysical investigations, anomaly

investigations, and two-foot surface clearance for munitions and explosives of concern (MEC»,

along with results of remedial actions conducted to date at the BRDA (Level A excavation

Explanation of Significant Differences Final G-Street Salvage Yard, Canal Creek Study Area March 2009 Aberdeen Proving Ground, Maryland Page 1-2

activities), have verified the location of the portion of the BRDA warranting use of Level A

personal protective equipment (PPE) and the need for a vapor containment structure (VCS). The

area requiring a VCS is much smaller than expected at the time of the ROD and has been fully

excavated. No chemical warfare items were found and no chemical warfare materiel (CWM)

was detected on any monitors during the excavation. As a result, continued use of Level A and a

VCS are not warranted for the remainder of the BRDA excavation. The ROD specifically states

that “all excavation work will be conducted by Explosive Ordnance Disposal (EOD) technicians

inside the VCS in Level A PPE.” This Explanation of Significant Differences (ESD) is

necessary in order to resolve this inconsistency.

In order to meet the full requirements of the National Oil and Hazardous Substances Pollution

Contingency Plan (NCP) §300.415(c)(2)(i) and CERCLA §117(c), a notice of availability

(NOA) will be published in a local newspaper (The Aegis) and will provide a brief description of

this ESD. In accordance with the EPA document, A Guide to Preparing Superfund Proposed

Plans, Records of Decision, and Other Remedy Selection Decision Documents (EPA, 1999), a

formal public comment period is not required when issuing an ESD; therefore, written public

comments will not be requested. The final ESD will be placed in the Administrative Record for

the site, located at the Edgewood and Aberdeen branches of the Harford County Library and the

Miller Library at Washington College in Chestertown, Kent County, MD.


2. SITE HISTORY, CONTAMINATION, AND SELECTED REMEDY

2.1 SITE HISTORY AND CONTAMINATION

Since 1917, the Edgewood Area of APG has been a center for research, development, testing,

and manufacture of military-related chemicals and chemical agents. The G-Street Salvage Yard

is located in the Edgewood Area of APG, which is listed on the National Priorities List (NPL).

The NPL is the EPA list of hazardous waste sites that have been identified as priorities for

remedial evaluation and response.

The G-Street Salvage Yard site was originally used as the World War I (WWI) Railroad Yard

until the World War II (WWII) Railroad Yard was constructed nearby. Salvage yard operations

at the site were conducted from the 1940s until the late 1960s, and operations were primarily

scrap wood and metal recycling, including a smelting operation for lead reclamation.

The BRDA received residue from burn pit disposal operations reportedly conducted in the APG

downrange areas of New O-Field and J-Field. The ash and metal residue were transported to the

Salvage Yard for scrap metal recovery and sale. Unexploded ordnance/chemical warfare material

(UXO/CWM) may have been transported and deposited at the BRDA along with the residual

burn material from the downrange areas.

2.2 SELECTED REMEDY AS ORIGINALLY DESCRIBED IN THE ROD

The Selected Remedy for the BRDA is Excavation with Off-Site Disposal and Land Use

Controls (LUCs). This remedy includes the following elements.

� Due to the potential presence of UXO/CWM in the BRDA, excavation and removal of materials will be conducted under the strict Army safety requirements of a UXO/CWM removal action. All intrusive operations into the BRDA burn residue material will be performed in a vapor containment structure (VCS) to contain a potential CWM release from a chemical agent bomblet.

� Removal of the existing safety cover using low ground pressure earthmoving equipment. This safety cover consists of clean sand and other materials, and will be handled on-site as clean material unless otherwise indicated by visual observations, sampling, or as indicated in the Remedial Design.


� Excavation of approximately 533 yd3 of contaminated surface soils (0 to 2 feet below ground surface (bgs)) using low ground pressure earthmoving equipment and excavation of an estimated 2,800 yd3 of BRDA burn residue material. All excavation activities will be conducted by qualified EOD technicians due to the potential for encountering UXO/CWM. Soil will be both hand and mechanically excavated, cleared of potential UXO/CWM, and containerized. The VCS will be outfitted with an air filtration system to maintain a negative air pressure and remove an agent vapor release if one were to occur. An extensive air monitoring program will be established to ensure worker and public safety. Real-time monitoring of meteorological conditions and audio/video monitoring of the excavation team activities will be performed. Excavation workers inside the VCS will wear Level A personal protective equipment to protect against potential exposure to CWM.

� Sloping or benching will be required for excavation depths below 4 feet in accordance with Occupational Safety and Health Administration (OSHA) requirements. All contaminated soil/material removed from the BRDA and certified free of UXO/CWM will be turned over to the on-post hazardous waste contractor for transport to a treatment facility for disposal. Any UXO/CWM materials encountered will be turned over to the U.S. Army 22nd Chemical Battalion Technical Escort (TE) for disposal.

� On-site management of potentially contaminated and contaminated soil. All potentially contaminated soil will be handled on-site as hazardous waste until sampling indicates otherwise. Potentially contaminated soils will be stored in bermed areas on an impermeable membrane (e.g., polyethylene sheeting) to prevent run-on and subsurface contamination, or will be stored in roll-off containers. Soil piles and roll-off containers will be covered with impermeable covers, inspected, and maintained until final disposition.

� Management of contaminated soil and materials. Soil will be disposed at an appropriate disposal facility in compliance with applicable environmental laws and as determined based upon the results of the soil sample analyses.

� Sampling to determine the extent of surface soil excavation in the BRDA surface soils area. This area will be excavated to 2 feet bgs.

� Confirmation sampling in the BRDA burial area to ensure that contaminated soil has been removed to below applicable remedial goals (RGs).

� Site restoration/revegetation. Activities will include backfill of the excavation to original grade with clean soil, topsoil, and seed and mulch. The sample results from proposed backfill material will be provided to EPA and MDE for acceptance.

� Implementation of LUCs prohibiting residential land use and soil disturbance at a depth greater than the excavation depth if contamination is present at levels exceeding the RGs.


� CERCLA 121(c) Five-Year Reviews will be conducted to assess the long-term effectiveness of the remedy (including the LUCs) until chemicals of concern (COCs) in the soil are detected at levels that allow for unlimited use and unrestricted exposure.

The Selected Remedy for the BRDA is Excavation and Off-Site Disposal. This Selected Remedy

includes LUCs. By removing contaminated soil and implementing LUCs, the Selected Remedy

for the BRDA meets the requirements of CERCLA and the NCP and will:

� Prevent ecological exposure to soil containing mean concentrations of COCs in excess of RGs.

� Prevent residential exposure to hazardous substances in soil that may pose unacceptable risk.

� Prevent transport and migration of site COCs to nearby marshes and/or creeks.


3. BASIS FOR DOCUMENT

This decision document presents the ESD for the Selected Remedy for one of the two areas

within the G-Street Salvage Yard in the Canal Creek Study Area, Edgewood, Maryland, which

was chosen in accordance with CERCLA, as amended by the Superfund Amendments and

Reauthorization Act (SARA), and, to the extent practicable, the NCP. This decision is based on

the Administrative Record file for this site.

The State of Maryland concurs with the ESD for the Selected Remedy.

The results of additional investigations conducted at the BRDA as part of the Remedial Design

and Remedial phases of the project indicate that the portion of the BRDA requiring Level A

excavation under a VCS is smaller than indicated in the ROD. The total surface area to be

excavated in Level A under the VCS as presented in the ROD was 15,246 square feet. The total

surface area to be excavated in Level A under the VCS as presented in this ESD is 2,500 square

feet. The following subsections provide the information supporting this ESD.

3.1 POST-ROD INVESTIGATIONS

Additional investigations were conducted at the BRDA after the ROD was signed in September

2007 that have resulted in information supporting the modification outlined in this ESD.

3.1.1 Geophysical Investigations, December 2007 – February 2008

In 1998, a geophysical investigation was conducted in order to document the location and extent

of the BRDA burial area that had been partially excavated during the Removal Action in 1990

((ICF Kaiser (ICF), 1998). The 1998 investigation concluded that a large portion of the G-Street

Salvage Yard (approximately 60 feet by 200 feet) contained metallic anomalies and one portion

of this area appeared to have ground disturbance to a total depth of approximately 9 feet. This

large area was erroneously identified as the “BRDA” in the 1998 report, and the location of this

area was unclearly defined. The location and total area of the BRDA specified in the ROD was

based upon this 1998 report.


As part of an effort to further define the extent of the BRDA burial area during the Remedial

Design phase, a geophysical investigation of the BRDA was completed in December 2007

(WESTON, 2007). The purpose of this investigation was to identify the exact location of the

BRDA in order to verify the size, location, and site preparation requirements for the VCS.

Results of the December 2007 geophysical investigation confirmed that the location of the

BRDA, as defined in the 1998 report and subsequently the ROD, was incorrectly mapped. In

addition, this geophysical investigation indicated that the area defined as the “BRDA” consisted

of numerous small metallic anomalies (not a single large anomaly as indicated in the 1998

report), the majority of which were confirmed through Ground Penetrating Radar (GPR) to be

shallow surface debris (1 to 2 feet bgs) present just below the sand cover installed after the 1990

removal action. This December 2007 geophysical investigation indicated that the BRDA burial

area partially excavated during the 1990 removal action was much smaller than indicated in the

1998 report and the ROD.

Because of the inaccuracies and inconsistencies in the 1998 geophysical report, which were

discovered as a result of the December 2007 geophysical investigation, further geophysical

investigations were conducted using more detailed and more accurate techniques in January and

February 2008 to identify the true location and extent of the BRDA burial area (WESTON,

2008b). Based upon the January and February 2008 geophysical investigation, as well as

interviews with personnel familiar with the 1990 removal action at the BRDA, the suspected

BRDA burial area was tentatively identified as “anomaly C” in a February 25, 2008 letter report

summarizing those activities (WESTON, 2008a). That report indicated that other

electromagnetic anomalies within the erroneously enlarged “BRDA” identified in the 1998

geophysical report were not consistent with a burial area, but were more consistent with a

pushout area or surface debris similar to that which had been encountered over the entire Salvage

Yard Soil Area portion of the site, which had been cleared for MEC to 2 feet bgs from December

2007 to February 2008.


3.1.2 Anomaly Verification, February 2008

Utilizing Army-approved procedures and safety precautions, anomaly verification activities were

completed in February 2008 consisting of test digs at the various BRDA geophysical anomalies

identified in the December 2007 to February 2008 geophysical investigations. These

investigations were conducted as part of the 2-foot MEC clearance activities that were on-going

at the site at that time, and were executed under an Army-approved safety plan. A report

documenting the results of this investigation of the BRDA was submitted to the Army on

February 25, 2008 (WESTON, 2008a).

The results of this intensive investigation of the BRDA verified that “anomaly C” was the most

likely candidate for the true location of the BRDA burial area originally partially excavated as

part of the removal action in 1990. This was evidenced primarily by the electromagnetic

signature (consistent with buried metallic debris), the conductive signature (consistent with

buried mixed debris), GPR profiles (consistent with a disturbed area containing debris to a total

depth of approximately 7 feet bgs), and the verification of a decomposing layer of woodchips

encountered at approximately 2 feet bgs (consistent with personnel interviews of individuals

intimately familiar with the 1990 removal action). With the exception of anomaly “C,” all of the

other significant and suspect anomalies were investigated to approximately 12 feet bgs and

native soils. Test excavations at anomaly “C” were halted at the decomposing woodchip layer.

Additional test digs were conducted in areas both outside of and within the erroneously large

“BRDA” as defined in the ROD to verify positive and negative geophysical investigation results.

No other test digs encountered buried materials consistent with the suspect burial area.

3.1.3 Remedial Design Appendix F

Based upon the results of the additional investigations conducted between December 2007 and

February 2008, a revised excavation approach for the BRDA was outlined in Appendix F of the

Remedial Design for the G-Street Salvage Yard, which is available in the Administrative Record

for the site (USAGAPG, 2008). This revised excavation approach included Level A excavation

of anomaly “C” within a 40-foot-diameter round VCS, followed by an assessment of findings

from that excavation to determine the subsequent need for the VCS at other BRDA locations.


The revised approach included a risk assessment and approval process involving the Army, EPA,

and MDE.

3.2 LEVEL A EXCAVATION ACTIVITIES, OCTOBER 2008

A 40-foot-round VCS was procured for the Level A excavation activities at and adjacent to

anomaly “C” within the BRDA. Level A excavation activities were conducted in October 2008.

The results of the Level A excavation activities at and around anomaly “C” within the BRDA in

October 2008 are consistent with the conclusions presented in Appendix F of the Remedial

Design for the G-Street Salvage Yard (i.e., that additional excavations within other portions of

the erroneously large “BRDA” as defined in the ROD can proceed in accordance with surface

soil excavation procedures outlined in the ROD). These conclusions were verified through the

following observations:

� Anomaly “C” was a well-defined burial area within the BRDA, and was entirely consistent with the size, depth, and materials predicted by the geophysical investigations conducted from December 2007 to February 2008.

� Materials excavated from anomaly “C” were entirely consistent with those reported during the 1990 removal action. These materials included E54-series and E118-series chemical bomblets, glassware, and other materials.

� Other excavated anomalies around anomaly “C” were entirely consistent with the size, depth, and materials predicted by the geophysical investigations conducted from December 2007 to February 2008.

� Materials excavated from the other anomalies around anomaly “C” were entirely consistent with materials excavated from the Salvage Yard Soil Area of the G-Street Salvage Yard site. These materials included metallic scrap debris, construction debris, and non-hazardous MEC scrap.

The potential for encountering CWM in the remaining portions of the BRDA was evaluated in a

November 2008 Risk Assessment and was downgraded from “medium” to “low” risk

(WESTON, 2008c). This assessment of “low” risk was warranted because there have been no

confirmed detections of chemical warfare agent during any of the Level A excavation activities

under the VCS, and there have been no confirmed chemical agent detections in any of the MEC

items removed from the site and investigated by the 22nd Chemical Battalion or Edgewood

Chemical Biological Center (ECBC). This assessment is supported by the following


observations made during the October 2008 Level A excavation activities conducted under the

VCS at and around anomaly “C”:

� There have been no confirmed chemical warfare agent detections on the MiniCAMS air monitors (near-real time air monitoring conducted at the chemical agent filtration system (CAFS) at the pre-, mid-, and post-filter locations).

� There have been no chemical warfare agent detections in the low-level confirmation depot area air monitoring system (DAAMS) tubes collected from the MiniCAMS CAFS monitoring locations.

� There have been no chemical warfare agent detections in any of the excavated debris or soil low-level DAAMS tubes vapor screening samples.

� There have been no chemical warfare agent or chemical warfare agent degradation product detections in any of the waste soil or post-excavation verification soil samples.

� There have been no chemical warfare agent detections in any of the liquids present in the chemical bomblets or glassware evaluated by the 22nd Chemical Battalion or ECBC.

Based upon this information, the following modifications will be made to the excavation

approach for the remaining portions of the BRDA:

� All remaining areas of the BRDA will be excavated in accordance with the procedures outlined in Section 12.2.2, titled “Excavation and Off-site Disposal Remedy for the BRDA”, of the ROD.

3.3 CWM/UXO RISK ASSESSMENT FOR THE G-STREET SALVAGE YARD BURN RESIDUE DISPOSAL AREA

A risk assessment was prepared in November 2008 incorporating the results of the post-ROD

investigation activities and the results of the Level A excavation activities conducted in October

2008. This risk assessment determined that the risk for encountering CWM in the remainder of

the BRDA was low. As a result, this risk assessment determined that standard Army safety

protocol for intrusive activities at APG was protective of site personnel and the public, and that

Level A PPE and a VCS were no longer warranted.


4. DESCRIPTION OF SIGNIFICANT DIFFERENCES

4.1 SCOPE

There is no change in scope. The entire BRDA will be addressed as indicated in the ROD and

the completed remedial action at the BRDA will meet the Remedial Action Objectives.

4.2 PERFORMANCE

The significant difference between the remedy as described in the ROD and as described in this

document relates directly to the use of the VCS and Level A PPE within the footprint of the area

identified as the “BRDA” in the ROD. The area of concern within the BRDA that warranted the

use of the VCS and Level A PPE was known to be a relatively small burial location partially

excavated during the 1990 removal action. At the time the ROD was signed, the exact location

of this burial location was unknown; therefore, the use of the VCS and Level A PPE was selected

for the entire area identified as the BRDA in the ROD.

Post-ROD information has been collected at the site, along with results of the Level A

excavation activities conducted in October 2008, which has verified that the burial location of

concern was anomaly “C” within the BRDA, and that the remainder of the area identified as the

BRDA in the ROD is more consistent with surface debris similar to that encountered throughout

the entire G-Street Salvage Yard Site. Therefore, while strict Army safety protocol and

procedures are necessary and will continue to be utilized at the BRDA, use of a VCS and Level

A PPE are not warranted. The following modified excavation approach will be utilized at the

remainder of the BRDA:

� Excavation of contaminated surface soils (0 to 2 feet bgs) using low ground pressure earthmoving equipment and excavation of remaining BRDA burn residue material. All excavation activities will be conducted by qualified EOD technicians due to the potential for encountering UXO. This work will be performed by EOD technicians in Level D protection. Soil will be both hand and mechanically excavated, cleared of potential UXO/CWM, and containerized. All potentially contaminated soil will be handled on-site as hazardous waste until sampling indicates otherwise. Potentially contaminated soils will be stored in bermed areas on an impermeable membrane (e.g., polyethylene sheeting) to prevent run-on and subsurface contamination, or will be


stored in roll-off containers. Soil piles and roll-off containers will be covered with impermeable covers, inspected, and maintained until final disposition.

All other components of the modified approach are entirely consistent with the Selected Remedy

as presented in the ROD, and no other modifications are proposed in this decision document. A

direct side-by-side comparison of the Selected Remedy for the BRDA as presented in the ROD

and the modifications outlined in this ESD is provided in Table 1. A graphical depiction of the

specific portion of the BRDA to which the ESD modifications apply is presented in Figure 1.

4.3 COST

The entire BRDA will be addressed under the existing fixed price performance based contract

and will meet the Remedial Action Objectives. Since this is a fixed price performance based

contract, there is no change in cost.

4.4 EXPECTED OUTCOMES

The approach outlined in this document is consistent with the Selected Remedy presented in the

ROD. All Remedial Action Objectives will be met. It is expected that the time to complete the

remedial action at the BRDA will be reduced by approximately 4 weeks.


Table 1 Direct Side-by-Side Comparison of Selected Remedy and Modifications

Description of the Selected Remedy as Presented in the ROD

Description of the Selected Remedy as Modified in this ESD

� Due to the potential presence of UXO/CWM in the BRDA, excavation and removal of materials will be conducted under the strict Army safety requirements of a UXO/CWM removal action. All intrusive operations into the BRDA burn residue material will be performed in a vapor containment structure (VCS) to contain a potential CWM release from a chemical agent bomblet.

� Due to the potential presence of UXO in the remaining portions of the BRDA, excavation and removal of materials will be conducted under the strict Army safety requirements of a UXO/CWM removal action.

� Removal of the existing safety cover using low ground pressure earthmoving equipment. This safety cover consists of clean sand and other materials, and will be handled on-site as clean material unless otherwise indicated by visual observations, sampling, or as indicated in the Remedial Design.

No change.

� Excavation of approximately 533 yd3 of contaminated � Excavation of contaminated surface soils (0 to 2 surface soils (0 to 2 feet bgs) using low ground pressure feet bgs) using low ground pressure earthmoving earthmoving equipment and excavation of an estimated equipment and excavation of remaining BRDA 2,800 yd3 of BRDA burn residue material. All burn residue material. All excavation activities excavation activities will be conducted by qualified will be conducted by qualified EOD technicians EOD technicians due to the potential for encountering due to the potential for encountering UXO. This UXO/CWM. Soil will be both hand and mechanically work will be performed by EOD technicians in excavated, cleared of potential UXO/CWM, and Level D protection. Soil will be both hand and containerized. The VCS will be outfitted with an air mechanically excavated, cleared of potential filtration system to maintain a negative air pressure and UXO/CWM, and containerized. All potentially remove an agent vapor release if one were to occur. An contaminated soil will be handled on-site as extensive air monitoring program will be established to hazardous waste until sampling indicates ensure worker and public safety. Real-time monitoring otherwise. Potentially contaminated soils will be of meteorological conditions and audio/video monitoring stored in bermed areas on an impermeable of the excavation team activities will be performed. membrane (e.g., polyethylene sheeting) to Excavation workers inside the VCS will wear Level A prevent run-on and subsurface contamination, or personal protective equipment to protect against will be stored in roll-off containers. Soil piles potential exposure to CWM. and roll-off containers will be covered with

impermeable covers, inspected, and maintained until final disposition.

� Sloping or benching will be required for excavation depths below 4 feet in accordance with Occupational Safety and Health Administration (OSHA) requirements. All contaminated soil/material removed from the BRDA and certified free of UXO/CWM will be turned over to the on-post hazardous waste contractor for transport to a treatment facility for disposal. Any UXO/CWM materials encountered will be turned over to the U.S. Army 22nd Chemical Battalion Technical Escort (TE) for disposal.

No change.


Table 1 Direct Side-by-Side Comparison of Selected Remedy and Modifications (Continued)

Description of the Selected Remedy as Presented in the ROD

Description of the Selected Remedy as Modified in this ESD

� On-site management of potentially contaminated and contaminated soil. All potentially contaminated soil will be handled on-site as hazardous waste until sampling indicates otherwise. Potentially contaminated soils will be stored in bermed areas on an impermeable membrane (e.g., polyethylene sheeting) to prevent run-on and subsurface contamination, or will be stored in roll-off containers. Soil piles and roll-off containers will be covered with impermeable covers, inspected, and maintained until final disposition.

No change.

� Management of contaminated soil and materials. Soil will be disposed at an appropriate disposal facility in compliance with applicable environmental laws and as determined based upon the results of the soil sample analyses.

No change.

� Sampling to determine the extent of surface soil excavation in the BRDA surface soils area. This area will be excavated to 2 feet bgs.

No change.

� Confirmation sampling in the BRDA burial area to ensure that contaminated soil has been removed to below applicable RGs.

No change.

� Site restoration/revegetation. Activities will include backfill of the excavation to original grade with clean soil, topsoil, and seed and mulch. The sample results from proposed backfill material will be provided to EPA and MDE for acceptance.

No change.

� Implementation of LUCs prohibiting residential land use and soil disturbance at a depth greater than the excavation depth if contamination is present at levels exceeding the RGs. The approximate extent of LUCs is shown in Figure 3, p. 13 of the ROD.

No change.

� CERCLA 121(c) Five-Year Reviews will be conducted to assess the long-term effectiveness of the remedy (including the LUCs) until chemicals of concern (COCs) in the soil are detected at levels that allow for unlimited use and unrestricted exposure.

No change.

Location Map

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Portion of BRDA to be Excavatedin Accordance with the ROD

Portion of BRDA to be Excavatedin Accordance with the ESD

'""Feet

Figure 1BRDA in Accordance with

the ROD vs. the ESD


Figure 1 BRDA in Accordance with the ROD vs. the ESD


5. SUPPORT AGENCY COMMENTS

EPA and MDE comments were solicited throughout the development of the modified approach

to the excavation of the BRDA in the form of daily activity reports, monthly project status

meetings, monthly RAB meetings, presentation of findings from the Level A BRDA excavation

activities, and review of this ESD document.

5.1 COMMENTS DURING DEVELOPMENT OF THE MODIFIED APPROACH

Based upon the information collected after the signing of the ROD in September 2007, the EPA

and MDE concurred with the basis for the modified approach to the excavation of the BRDA.

This modified approach was discussed with EPA and MDE at monthly project status meetings

from April 2008 through October 2008, and the detailed discussion of the approach was

reviewed by EPA and MDE as Appendix F to the Remedial Design. While this type of change

(e.g., tactical approach for executing the remedy) typically would be considered a minor change

and would not require an ESD, EPA and MDE determined that this particular change affects

engineering controls established for public protection, and therefore requires an ESD. Because

public outreach efforts at the site have included both on-post and off-post communities, and

because the Restoration Advisory Board (RAB) has been frequently updated on the progress and

approach for the BRDA at the G-Street Salvage Yard site, EPA and MDE concurred that a ROD

amendment was not warranted.

In accordance with the EPA document, A Guide to Preparing Superfund Proposed Plans,

Records of Decision, and Other Remedy Selection Decision Documents (EPA, 1999), and since

on-going public involvement at the site (in the form of two on-site public open houses and

periodic briefings to the RAB) has included the modified approach to the excavation of the

BRDA, EPA and MDE concurred that excavation activities at the BRDA could proceed as

modified while the ESD was being prepared and made available to the public.

5.2 COMMENTS ON THE ESD

A Draft ESD was submitted to EPA and MDE for review and comment on 17 November 2009.


6. STATUTORY DETERMINATIONS

The Army has determined that the completed BRDA remedial action, as modified, will meet the

Remedial Action Objectives specified in the ROD.

The Selected Remedy, as modified, for the G-Street Salvage Yard BRDA is protective of human

health and the environment, complies with Federal and State requirements that are applicable or

relevant and appropriate to the remedial action, is cost-effective, and utilizes permanent solutions

and alternative treatment technologies to the maximum extent practicable. The Selected

Remedy, as modified, meets the requirements of CERCLA §121, except as already noted in the

ROD, which is summarized below:

� The Selected Remedy for the G-Street Salvage Yard BRDA does not satisfy the statutory preference for treatment as a principal element of the remedy, but relies on removal and off-site disposal of contaminated soil and materials.

� Because the Selected Remedy may result in hazardous substances, pollutants, or contaminants remaining on-site above levels that allow for unlimited use and unrestricted exposure, a statutory review will be required. Generally, this review is conducted within 5 years after initiation of remedial action to ensure that the remedy is, or will be, protective of human health and the environment. At APG, EPA Region III and EPA Headquarters have determined that basewide Five-Year Reviews are appropriate rather than OU-based Five-Year Reviews. Therefore, the review of the BRDA at the G-Street Salvage Yard site will be conducted as part of the APG basewide Five-Year Reviews. The next APG basewide Five-Year Review will be conducted in October 2013. Additionally, LUCs will be implemented to prevent future military family housing, elementary and secondary schools, child care facilities, playgrounds, and non-military residential land use from being constructed at the site.


7. PUBLIC PARTICIPATION COMPLIANCE

The following summarizes the public participation for the Proposed Plan:

� The public comment period on the Proposed Plan ran from 25 June 2007 to 8 August 2007. Copies of the Proposed Plan were made available to the public through the APG Administrative Record locations at the Edgewood and Aberdeen branches of the Harford County Library and the Miller Library at Washington College in Chestertown, Kent County, MD.

� 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, The Cecil Whig, The East County Times, and The Kent County News.

� 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 Installation Restoration Program (IRP) mailing list. The fact sheet included a form which citizens could use to send APG their comments.

� On 25 June 2007, APG held a public meeting at the Edgewood Senior Center in Edgewood, Maryland. Representatives of the Army, EPA, and MDE were present at the meeting. APG representatives presented information on the Salvage Yard Soil Area and BRDA, and on the proposed remedial actions. A full transcript of the meeting is available in the Administrative Record

The following summarizes the public participation associated with the modification to the BRDA

excavation approach presented in this ESD:

� An APG-Community Open House was held at the G-Street Salvage Yard Site on 10 September 2008 to answer APG-community questions and to receive comments. This open house was advertised in the on-post newspaper, APG News, was advertised on flyers posted in common areas at APG, and was open to all post personnel. At that time, all site equipment was present for public review, including the reduced-size (40foot-round) VCS.

� A Community Open House was held at the G-Street Salvage Yard Site on 13 September 2008 to answer community questions and to receive comments. This open house was advertised in The Aegis (a local newspaper), and invitations were extended to elected officials and other members of the local community. This event was open to the general public. At that time, all site equipment was present for public review, including the reduced-size (40-foot-round) VCS.


� The results of the post-ROD investigations, and the Army’s intent to utilize a 40-footround VCS at the BRDA have been discussed at APG RAB meetings between March and October 2008.

In order to meet the full requirements of the NCP §300.415(c)(2)(i), an NOA will be published in

a local newspaper (The Aegis) and will provide a brief description of this ESD. In accordance

with the EPA document, A Guide to Preparing Superfund Proposed Plans, Records of Decision,

and Other Remedy Selection Decision Documents (EPA, 1999), a formal public comment period

is not required when issuing an ESD; therefore, written public comments will not be requested.

The final ESD will be placed in the Administrative Record for the site, located at the Edgewood

and Aberdeen branches of the Harford County Library and the Miller Library at Washington

College in Chestertown, Kent County, MD.


8. REFERENCES

EPA. (U.S. Environmental Protection Agency). 1999. A Guide to Preparing Superfund Proposed Plans, Records of Decision, and Other Remedy Selection Decision Documents. OSWER 9200.1-23-P, EPA 540-R-98-031, PB98-963241. 30 July 1999.

ICF (ICF Kaiser). 1998. Geophysical Survey at the G-Street Salvage Yard. 10 October 1998.

USAGAPG (U.S. Army Garrison Aberdeen Proving Ground). 2007. Canal Creek Study Area Record of Decision for Remedial Action - G-Street Salvage Yard Final. September 2007. Prepared by Weston Solutions, Inc. for USAGAPG Environmental Conservation and Restoration Division.

USAGAPG. 2008. Canal Creek Study Area Remedial Design for Remedial Actions at the G-Street Salvage Yard, Aberdeen Proving Ground, MD – Final. April 2008.

WESTON (Weston Solutions, Inc.). 2007. Geophysical Survey of the BRDA.

WESTON. 2008a. G-Street BRDA Subsurface Investigation Results. 25 February 2008.

WESTON. 2008b. BRDA Site Overview.

WESTON. 2008c. Final UXO/CWM Risk Assessment for Remedial Action at the G-Street Salvage Yard Burn Residue Disposal Area, Canal Creek Study Area, Aberdeen Proving Ground, Maryland. 10 November 2008.

______________________________________________________________________________

______________________________________________________________________________


9. AUTHORIZING SIGNATURES

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

Maria R. Gervais Date Colonel, U.S. Army Commanding, U.S. Army Environmental Command

James J. Burke Date Director Hazardous Site Cleanup Division U.S. Environmental Protection Agency, Region III