Second_Five-Year_Review.pdf

SECOND FIVE-YEAR REVIEW

Dobbins Air Reserve Base Marietta, Georgia

Revision 1 January 2014

PRIVILEGED AND CONFIDENTIAL

AFCEC Contract No. FA8903-08-D-8771 Task Order No. 0173

Project Number: FGWB20134310

SECOND FIVE-YEAR REVIEW

94th Airlift Wing Dobbins Air Reserve Base

Marietta, Georgia

Prepared for:

Air Force Civil Engineer Center

Contract No. FA8903-08-D-8771 Task Order No. 0173

Prepared by:

HDR

184 Creekside Park, Suite 100 Spring Branch, Texas 78070

This document was prepared for submittal to the U.S. Government only and contains confidential and proprietary information.

Second Five-Year Review January 2014 Dobbins ARB – Marietta, Georgia Revision 1 iii

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY ....................................................................................................................... ix

1.0 INTRODUCTION

2.0 SITE CHRONOLOGY

3.0 BACKGROUND

3.1 PHYSICAL CHARACTERISTICS

3.2 LAND AND RESOURCE USE

3.3 HISTORY OF CONTAMINATION

3.3.1 Past Base Landfill, LF001

3.3.2 Past Fire Pit Training Area, FT002

3.3.3 Present Fire Pit Training Area, FT003

3.3.4 Big Lake, OT004

3.3.5 AVGAS Sludge Burial Site A, DP005

3.3.6 AVGAS Sludge Burial Site B, DP006

3.3.7 Little Lake, OT007

3.3.8 Former Railroad Car Fuel Transfer Lines, ST008

3.3.9 Barrel Disposal Site, DA011

3.3.10 Oil/Water Separator 4A, OW504A

3.4 INITIAL RESPONSE

3.4.1 AVGAS Sludge Burial Site A, DP005

3.4.2 Former Railroad Car Fuel Transfer Lines, ST008

3.5 BASIS FOR TAKING ACTION

3.5.1 Risk Assessment

3.5.2 Decision Documents

4.0 REMEDIAL ACTIONS

4.1 REMEDY SELECTION

4.2 REMEDY IMPLEMENTATION

4.2.1 AVGAS Sludge Burial Site A, DP005

4.3 SYSTEM OPERATION AND MAINTENANCE

5.0 PROGRESS SINCE THE LAST FIVE-YEAR REVIEW

5.1 PREVIOUS FIVE-YEAR REVIEWS

5.1.1 Protectiveness Statements

5.1.2 Issues

5.1.3 Recommendations and Follow-up Actions

5.2 ACTIONS TAKEN

5.2.1 Site-Wide Activities

5.2.2 Site Activities

6.0 FIVE-YEAR REVIEW PROCESS

6.1 REVIEW COMPONENTS

6.2 COMMUNITY INVOLVEMENT

iv

6.3 DOCUMENT REVIEW

6.4 DATA REVIEW

6.5 SITE INSPECTION

6.6 INTERVIEWS

7.0 TECHNICAL ASSESSMENT

7.1 IS THE REMEDY FUNCTIONING AS INTENDED BY THE DECISION

DOCUMENTS?

7.2 ARE THE EXPOSURE ASSUMPTIONS, TOXICITY DATA, CLEANUP LEVELS,

AND REMEDIAL ACTION OBJECTIVES USED AT THE TIME OF THE REMEDY

SELECTION STILL VALID?

7.3 HAS ANY OTHER INFORMATION COME TO LIGHT THAT COULD CALL INTO

QUESTION THE PROTECTIVENESS OF THE REMEDY?

7.4 TECHNICAL ASSESSMENT SUMMARY

8.0 ISSUES

9.0 RECOMMENDATIONS AND FOLLOW-UP ACTIONS

10.0 PROTECTIVENESS STATEMENTS

11.0 NEXT REVIEW

12.0 REFERENCES

v

LIST OF APPENDICES

Appendix

A Community Notification

B Site Inspection Records and Photographs, October 2013

C Interview Records

LIST OF TABLES

Table

1 Summary of Selected Remedies

2 Monitoring Well Summary

3 Administrative Record Documents Since Initial Five-Year Review

LIST OF FIGURES

Figure

1 Base Aerial Photograph

2 Site Locations

3 LF001 Site Map

4 FT002 Site Map

5 FT003 Site Map

6 OT004 Site Map

7 DP005 Site Map

8 DP006 Site Map

9 OT007 Site Map

10 ST008 Site Map

11 DA011 Site Map

12 OW504A Site Map vi

LIST OF ACRONYMS AND ABBREVIATIONS

ACL alternate concentration limit

AFB Air Force Base

AFCEC Air Force Civil Engineer Center

AFFF Aqueous Film-Forming Foam

AFP6 Air Force Plant 6

AFRC Air Force Reserve Center

AR administrative record

ARAR applicable or relevant and appropriate requirements

ARB Air Reserve Base

AST aboveground storage tank

AVGAS Aviation Gasoline bgs below ground surface

BTEX benzene, toluene, ethylbenzene, and xylene

CAP Corrective Action Plan

CAR Comprehensive Analytical Report

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

COPC contaminants of potential concern

COPEC contaminants of potential ecological concern

DDD dichlorodiphenyldichloroethane

DDE dichlorodiphenyldichloroethene

DDT dichlorodiphenyltrichloroethane

DPE dual phase extraction

DVE dual phase vacuum extraction

ERA Ecological Risk Assessment

ESE Environmental Science & Engineering ft msl feet above mean sea level

FFS Focused Feasibility Study

FYR Five-Year Review

GA EPD Georgia Department of Natural Resources Environmental Protection Division vii

(CONTINUED)

GUST Georgia Underground Storage Tank

GWQS Georgia groundwater quality standards

HHRA Human Health Risk Assessment

HI Hazard Index

IRP Installation Restoration Program

ISWQS In-Stream Water Quality Standard

LTM Long-term Monitoring

LUC Land Use Control mg/kg milligrams per kilogram

MNA monitored natural attenuation

MTBE methyl tert-butyl ether

NAS Naval Air Station

NCP National Contingency Plan

NFA No Further Action

NFRAP No Further Response Action Planned

NOAA National Oceanic and Atmospheric Administration

OWS Oil/Water Separator

PAH polynuclear aromatic hydrocarbon

PBC performance-based cleanup

PBR performance based remediation

PCB polychlorinated biphenyls

PMP Project Management Plan

POL petroleum, oil, and lubricants

POP period of performance ppb parts per billion

RAB Restoration Advisory Board

RAO Remedial Action Objective

RC Response Complete

RI Remedial Investigation

RRS3 Georgia Type 3 Risk Reduction Standard

SC Site Closeout viii

(CONTINUED)

SCJV Sullivan Charter JV

SCS Site Characterization Summary

SRI Supplemental Remedial Investigation

SVE soil vapor extraction

SVOC semi-volatile organic compound

TCE trichloroethene

TO Task Order

TOC total organic carbon

TPH total petroleum hydrocarbon

USEPA United States Environmental Protection Agency

UST underground storage tank

USTMP Underground Storage Tank Management Program

UTL upper tolerance limit

UU/UE unlimited use and unrestricted exposure

VOC volatile organic compound

WP Work Plan µg/L micrograms per liter ix

EXECUTIVE SUMMARY

The purpose of this Five-Year Review (FYR) is to determine whether the remedy at Dobbins Air Reserve

Base (ARB) is, or upon completion will be, protective of human health and the environment. The lead agency for environmental restoration at Dobbins ARB is the 94th Airlift Wing of the 22nd Air Force. The regulatory oversight agency is the Georgia Department of Natural Resources Environmental Protection

Division (GA EPD). This is the second FYR for Dobbins ARB.

Dobbins ARB is located in eastern Cobb County on GA Highway 280 and is presently composed of approximately 1,666 acres with the primary mission to support elements of the military in training, supply, and equipment support. Dobbins ARB was established in 1943 and began operations in support of military aircraft production at Air Force Plant 6 (AFP6). The base was separated from AFP6 in 1947 when aircraft production was shut down after World War II and was established as the operator of the airfield. Air Force Reserve training became the dominant mission and has continued to the present.

Environmental restoration activities began with the Installation Restoration Program (IRP) in the 1980s.

An IRP Records Search for Dobbins ARB (CH2M HILL, 1982, AR0136) identified ten potential sites based on past waste management practices and potential for contamination migration. Six of the ten sites were recommended for further study and a seventh site was added:

Past Base Landfill, LF001

Past Fire Pit Training Area, FT002

Present Fire Pit Training Area, FT003

Big Lake, OT004

AVGAS Sludge Burial Site A, DP005

AVGAS Sludge Burial Site B, DP006

Little Lake, OT007

The Remedial Investigation (RI) Report (Parsons, 1995, AR0102) incorporated previous studies and included baseline risk assessments for each site assuming commercial/light industrial uses and recreational uses at Big Lake and Little Lake. The Comprehensive Analytical Report (CAR)

(Montgomery Watson, 1996, AR0132) summarized all analytical data collected to date. The results were used to assess the migration of contaminants within the environment, trends in data over time and the x level of risk posed by site contaminants to humans and the environment. The conclusions in the report were used to prepare decision documents for the sites.

Decision Documents for LF001, FT002, FT003, OT004, DP006 and OT007 were submitted to GA EPD in 1997; all recommended No Further Remedial Action Planned (NFRAP). The documents were re-submitted with supplemental information in 2000. A Decision Document for DP005 was not prepared at that time because of ongoing remediation of fuel contaminants using dual phase vapor extraction (DPE).

GA EPD concurred with the Decision Documents for FT002, FT003, DP006 and OT007 from June 2004 to February 2005. GA EPD responded in December 2005 that they did not concur with NFRAP recommendations for Big Lake (OT004) and Past Base Landfill (LF001) due to continued contamination at each site and lack of existing and future receptor risk models; additional RI was required by GA EPD at both sites.

The initial FYR for the seven sites (Shaw, 2009, AR0187) was completed in June 2009. The FYR found that the remedies were protective due to an absence of complete exposure pathways based on current land use. Some additional actions were recommended to insure long-term protection at LF001, OT004 and

OT007. The initial FYR did not identify major issues affecting current remedies or their effectiveness, but four issues were identified for further action: additional institutional controls and groundwater monitoring including replacement of two wells at LF001; evaluation of FT002 for monitored natural attenuation; and additional studies of possible offsite sources of contamination to OT004 and OT007.

The current FYR included review of the seven sites in the initial FYR and the following three sites:

Former Railroad Car Fuel Transfer Lines, ST008

Barrel Disposal Site, DA011

Oil/Water Separator 4A, OW504A

These sites were not included in the initial FYR because ST008 had been approved for No Further Action

(NFA) by GA EPD following remediation activities in 1998, and DA011 and OW504A had not been identified or fully investigated at that time.

The following activities were completed since the initial FYR in 2009:

A site-wide background study (CH2M HILL, 2011, AR0191), including samples collected from

Dobbins ARB, was conducted to establish background values to be used in future site management decisions at AFP6.

xi

Air Force guidance issued in 2011 refocused site activities toward achieving unrestricted use and unlimited exposure (UU/UE) where cost effective. A performance-based contract (PBC) was awarded for additional investigation and remediation at AFP6 and Dobbins ARB, with the goal of achieving UU/UE though remediation to residential standards.

The PBC includes eight of the ten sites at Dobbins ARB: LF001, FT002, FT003, OT004, DP006, OT007, DA011 and OW504A.

The two sites not included in the PBC agreement, DP005 and ST008, were approved for NFA by GA

EPD and are in active refueling areas.

The DPE system at DP005 was shutdown in 2008 and semiannual monitoring was performed through 2010. GA EPD approved the recommendation for NFA in March 2011.

Additional investigations were performed at OT004 and OT007 in accordance with the recommendations in the FYR.

Maintenance activities were performed at monitoring wells at several sites in 2011 and 2012.

Supplemental Remedial Investigation Work Plans (SRI WPs) are being prepared for the eight sites included in the PBC.

This second FYR has included public notification; review of site documents; interviews with project personnel at Dobbins ARB, GA EPD, and contractors; and site inspections.

Technical assessment and development of protectiveness statements were developed for the eight sites with selected remedies documented in decision documents: LF001, FT002, FT003, OT004, DP005, DP006, OT007 and ST008.

Four issues have been identified:

Additional remedial investigations at LF001 and OT004 required in the GA EPD response to the initial decision documents were not completed and groundwater monitoring at LF001 and FT002 recommended in the initial FYR was not performed.

Land use controls (LUCs) were a remedy component in the Decision Documents submitted in 2000, but documentation was not available for review. The LUCs should be developed and documented in accordance with applicable guidance for all sites where contaminants do not allow UU/UE.

Assumptions for future land use and exposure to contaminants in the risk assessments may no longer be appropriate based on 2011 Air Force guidance for achieving UU/UE where cost-effective. In xii addition, the potential for continuing contribution of contaminants at OT004 and OT007 may result in exposure to higher levels of contaminants than incorporated in the risk assessments.

The status of monitoring wells at Dobbins ARB should be confirmed and steps taken to maintain their security.

The issues do not affect current protectiveness because of incomplete exposure pathways or insignificant risks based on current land use and site restrictions, but they may affect future protectiveness. The protectiveness statements are summarized below:

The remedies at LF001, FT002, FT003, OT004, DP006 and OT007 are considered protective in the short-term, because there is no evidence that there is current exposure, but additional investigation, groundwater monitoring and/or updated risk assessments are required for the remedies to be protective in the long term.

The remedies at DP005 and ST008 are considered protective of human health and the environment, and exposure pathways that could result in unacceptable risks are being controlled.

The applicable LUCs should be documented at all sites where contaminants do not allow UU/UE.

1.0 INTRODUCTION

The lead agency for the environmental restoration activities at Dobbins Air Reserve Base (ARB) is the

94th Airlift Wing of the 22nd Air Force. The regulatory oversight agency is the Georgia Department of

Natural Resources Environmental Protection Division (GA EPD).

The purpose of this Five-Year Review (FYR) is to determine whether the remedy at Dobbins ARB is, or upon completion will be, protective of human health and the environment. The methods, findings, and conclusions of the review are documented in this report, and recommendations are provided to address issues identified during the review.

This FYR report is prepared pursuant to Comprehensive Environmental Response, Compensation, and

Liability Act (CERCLA) §121 and the National Contingency Plan (NCP). CERCLA §121 states: If the

President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review such remedial action no less often than each five years after the initiation of such remedial action to assure that human health and the environment are being protected by the remedial action being implemented. In addition, if upon such review it is the judgment of the President that action is appropriate at such site in accordance with section [104] or [106], the

President shall take or require such action. The President shall report to the Congress a list of facilities for which such review is required, the results of all such reviews, and any actions taken as a result of such reviews.

United States Environmental Protection Agency (USEPA) interpreted this requirement further in the

NCP; 40 Code of Federal Regulations (CFR) §300.430(f)(4)(ii) states: If a remedial action is selected that results in hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure, the lead agency shall review such action no less often than every five years after the initiation of the selected remedial action.

HDR performed the FYR and prepared this report under Contract No. FA8903-08-D-8771, Task Order

(TO) No. 0173 with the Air Force Civil Engineer Center (AFCEC). This review was performed in accordance with Comprehensive Five-Year Review Guidance (USEPA, 2001); the land use controls

(LUCs) were reviewed in accordance with Recommended Evaluation of Institutional Controls:

Supplement to the Comprehensive Five-Year Review Guidance (USEPA, 2011). The guidance states

“Unlimited use and unrestricted exposure” (UU/UE) means that the selected remedy will place no restrictions on the potential use of land or other natural resources.

The review included ten environmental restoration sites on Dobbins ARB:

1. Past Base Landfill, LF001

2. Past Fire Pit Training Area, FT002

3. Present Fire Pit Training Area, FT003

4. Big Lake, OT004

5. AVGAS Sludge Burial Site A, DP005

6. AVGAS Sludge Burial Site B, DP006

7. Little Lake, OT007

8. Former Railroad Car Fuel Transfer Lines, ST008

9. Barrel Disposal Site, DA011

10. Oil/Water Separator 4A, OW504A

This is the second FYR for Dobbins ARB. The initial review was completed in June 2009.

2.0 SITE CHRONOLOGY

Date Activity

1907 Big Lake, OT004 was constructed as backup water source for City of Marietta

1910 Little Lake, OT007 was constructed with an earthen dike

1943 Dobbins ARB established, initially named Rickenbacker Field.

1940s-1973 AVGAS Sludge Burial Site A, DP005 storage and handling facility for aviation fuels and waste disposal of sludge residues from cleaning tanks

1941-1974 Past Base Landfill, LF001 operating and used for waste disposal from base tenants

1950s-1970s Former Railroad Car Fuel Transfer Lines, ST008 used to fill the six 25,000 gallon underground storage tanks (USTs) at the Fuel Farm.

1950s-1974 Past Fire Training Area, FT002 stored and consumed petroleum, oil, and lubricant (POL) wastes during fire training exercises

1962 Little Lake, OT007 site of fish kill caused by application of pesticides

1974-Present Present Fire Training Area, FT003 for fire training exercises

1974- 1980 Past Base Landfill, LF001. Unauthorized dumping of yard wastes/construction demolition debris

AVGAS Sludge Burial Site B, DP006. An interviewee reported that 15 gallons of AVGAS may have been buried at the site

April 1982 Installation Restoration Program (IRP) Records search for Dobbins ARB

August 1986 IRP Phase II Stage 1 Confirmation/Quantification

1988-1989 Investigation for lateral and vertical limits of contamination at IRP sites

August 1991 Six USTs removed from AVGAS Sludge Burial Site A, DP005

1992 Remedial Investigation (RI) at IRP sites

September 1996 Comprehensive Analytical Report – LF001, FT002, FT003, OT004, DP005, DP006 and

OT007

June-July 1997 Preliminary Assessment/Site Investigation at ST008

September 1998 Fuel transfer lines removed and soil excavated at ST008. 310 gallons of petroleum in fuel lines removed for recycling. Clean soil used for backfill and contaminated soil stockpiled.

April 1999 Petroleum-contaminated soil (71 tons) and asphalt (20 tons) from ST008 transported for off-site disposal.

Date Activity

May 2000 Decision Documents with Supplemental Information submitted for LF001, FT002, FT003, OT004, DP006 and OT007 to GA EPD

February 2001 Corrective Action Plan (CAP) Part B for DP-05 approved by GA EPD

November 2001 GA EPD concurs with CAP Part A, No Further Remedial Action Planned (NFRAP) for

ST008

April 2004 Dual phase extraction (DPE) (vacuum-enhanced pump and treat) system with five remediation wells began operation at DP005. Quarterly monitoring 2004-2006 and semiannual monitoring 2006-2008.

May 2004 GA EPD concurs with NFRAP for DP006 per Decision Document

July 2004 GA EPD concurs with NFRAP for FT002 per Decision Document

January 2005 GA EPD concurs with NFRAP for FT003 per Decision Document

February 2005 GA EPD concurs with NFRAP for OT007 per Decision Document

December 2005 GA EPD does not concur with NFRAPs for LF001 and OT004 per Decision Documents

March 2009 GA EPD approved deactivation of the DPE system at DP005; system was shutdown following monitoring in December 2008. Post-shutdown semiannual monitoring to December 2010.

June 2009 First FYR Report

October 2009 DPE system at DP005 decontaminated and mothballed; equipment left in place.

August 2010 Final Evaluation Report for DA011

September 2010 Source Investigation and Long-term Management Plan for OT004 and OT007

March 2011 GA EPD approves No Further Action (NFA) at DP005

November 2011 Air Force Plant 6 (AFP6) Base-wide Background Study

February 2012 Additional Source Investigation at OT004 and OT007

August 2012

Technical Evaluation of OW504A

Inspection and Maintenance of DPE system at DP005

Long-term Management (Inspections and Maintenance) at LF001, FT002, FT003, OT004, RP005, DP006 and OT007

3.0 BACKGROUND

3.1 PHYSICAL CHARACTERISTICS

Dobbins ARB is located in eastern Cobb County on GA Highway 280 approximately 1 mile west from

Exit 261 on Interstate-75. The base is presently composed of approximately 1,666 acres with the primary mission to support elements of the military in training, supply, and equipment support.

Dobbins ARB and the surrounding area occupy a gently rolling plateau that slopes gradually downward to the southeast. Elevations range from about 1,100 feet above mean sea level (ft msl) at the northwestern corner of the base to approximately 950 ft msl at the southwestern corner. The plateau is dissected by several small streams within the Chattahoochee River watershed. Rottenwood Creek flows through the northeast part of the base; a tributary, which joins Rottenwood Creek where it leaves the base property, was dammed to form Big Lake. Poorhouse Creek drains the southern portion of the base and flows into

Rottenwood Creek east of Dobbins ARB. Rottenwood Creek enters the Chattahoochee River, approximately 5 miles southeast of Dobbins ARB. Groundwater flow generally mimics the surface topography with groundwater discharge into the creeks documented at some locations.

Dobbins ARB is in the Central Uplands district of the Piedmont physiographic province, which is characterized by a series of low, linear ridges separated by broad, open valleys. Streams flowing through this area are generally transverse to the underlying geologic structure and occupy valleys 150 to 200 feet below the ridge crests. Bedrock strata in the area are termed the Sandy Springs Group, consisting of the

Powers Ferry Formation (interbedded gneisses, schists and amphibolites), the Chattahoochee Palisades

Quartzite (quartzite, locally feldspethic or micaceous), and the Factory Shoals Formation (interbedded metagraywacke and schists). Naturally occurring soils are saprolitic, consisting primarily of micaceous clayey silts and micaceous sandy silts that retain the structural features of the parent bedrock. The weathered erosional surface of the rock is irregular, so depth to competent bedrock is variable across the base.

Dobbins ARB receives potable water from the Cobb-Marietta Water Authority through AFP6. No public groundwater supply wells exist within 3 miles of Dobbins ARB. Sixteen water supply wells were installed on Dobbins ARB or AFP6, but have been inactive since the early 1950s. The initial FYR (Shaw, 2009, AR0187) stated 15 wells were filled and covered during the early 1980s and are no longer accessible; the closure status of the remaining inactive well was reported to not be known. The IRP RI

(Parsons, 1995, AR0102) stated the remaining well was used for sampling at AFP6. The 16 water supply wells were noted on a site map in the IRP Phase II Confirmation/Quantification Final Report

(Environmental Science & Engineering [ESE], 1986, AR0113) and samples were collected from seven of the wells. The wells were reported to be less than 300 feet deep and to have a combined yield of approximately 0.5 million gallons per day. The wells were installed to provide a backup if an adequate water supply was not available from the water authority. A report describing abandonment of the water supply wells was not found in the Administrative Record (AR).

3.2 LAND AND RESOURCE USE

Dobbins ARB was established in 1943 when the federal government acquired 2,843 acres of land to be used as an assembly site for B-29 aircraft by the Bell Aircraft Corporation. The Army Air Force maintained the resultant airfield, known as Rickenbacker Field, after the Bell operations ceased in 1947.

In 1948, the base was renamed Marietta Air Force Base (AFB). The Air Force Reserve Center (AFRC)

94th Bomb Wing was activated in 1949 and reserve training became the dominant mission. Marietta AFB was renamed Dobbins AFB in 1950. The name changed again in 1993 to Dobbins ARB. The 94th Airlift

Wing of the 22nd Air Force is currently the host unit at Dobbins ARB.

The Dobbins ARB facility began operations in support of military aircraft production at AFP6. The base was separated from AFP6 in 1947 when aircraft production was shut down after World War II and was established as the operator of the airfield and supporting land covering approximately 2800 acres. AFP6 retained approximately 709 acres. Subsequently, Dobbins ARB transferred approximately 1,100 acres to local municipalities (Cobb County, Marietta and Smyrna) and to the Department of the Navy, which developed Naval Air Station Atlanta (NAS Atlanta). The State of Georgia announced the acquisition of

NAS Atlanta in 2007 after it was recommended for closure in the 2005 Defense Base Closure and

Realignment Commission report; formal transfer occurred in September 2009. The facility, renamed the

General Lucius Clay National Guard Center, will serve as the new headquarters of the Georgia Army

National Guard.

Dobbins ARB is adjacent to the cities of Marietta to the north and Smyrna to the south. The base is roughly bounded by South Cobb Drive on the north, Cobb Parkway on the east, Windy Hill Road on the south and Atlanta Road on the west. The past and existing land use was described in the Community

Relations Plan (Dobbins, 1999, AR0165). The Dobbins ARB property was originally rural farmland on gently rolling hills approximately 2 miles southeast of Marietta and 2 miles northeast of Smyrna. The original Cobb County Airport, built in 1939 and on which AFP6 and the Airfield were built, was expanded with the addition of three 1-mile-long runways. The adjacent area was composed primarily of farms and individual lot houses with a very low population density. The creation of AFP6 created a housing boom in the Marietta/Smyrna area. During the late 1950's and 60's, Interstate-75 was constructed approximately one mile to the east of the Base. Light industry developed in pockets primarily along the major roads and railways running through the County.

The surrounding area began to grow again after AFP6 was re-opened in 1952; Cobb County was identified as the fastest growing county in the country during the late 1960's and 1970's. The area to the east of the base is highly developed for light industrial, commercial, retail and multi-family residential;

the area immediately to the north includes two colleges (Life University and Southern Polytechnic State

University), wooded areas, and office/commercial developments; the area immediately west of the base is composed of commercial development along Atlanta Road with residential use further west; and the area south of the base has a golf course and park adjacent to the base with residential development further south. The Chattahoochee National River Recreation Area is located approximately 5 miles downstream

(southeast) of Dobbins and Kennesaw National Battlefield is located 6 miles north of Dobbins. An aerial photograph of Dobbins ARB and the surrounding area is shown on Figure 1.

3.3 HISTORY OF CONTAMINATION

An IRP Records Search for Dobbins ARB (CH2M HILL, 1982, AR0136) was conducted to identify the potential for environmental contamination from past waste management practices and to assess the probability for contamination migration. Ten sites were initially identified as having potential contamination. Six of the ten sites listed above were determined to have significant potential for contaminant migration and recommended for further study.

The IRP Phase II Confirmation/Quantification Final Report (ESE, 1986, AR0113) was conducted to confirm the presence and/or migration of contaminants at the six sites recommended for study in the IRP

Records Search, as well as Little Lake. Investigations consisted of geophysical surveys, soil gas surveys, the installation groundwater monitoring wells, and sampling and analysis of groundwater, soils, surface water, and sediments.

The IRP Final Site Characterization Summary (SCS) (ESE, 1991, AR0118) presented the findings of additional field investigation conducted in two phases to quantify the extent and nature of contamination at each of the seven sites. The first phase was conducted at all seven sites from October 1988 through

February 1989. Based on those result, additional investigations were conducted at FT003, DP005, DP006, and OT007 from June through September 1990. The investigation consisted of soil borings, soil gas surveys, monitor well installation and groundwater sampling, and surface water and sediment sampling.

Additional investigation was conducted in 1995 and the RI report was completed (Parsons, 1995, AR0102). Analytical data collected during the IRP Phase II Study and the SCS were supplemented with additional data from the chemical analysis of surface and subsurface soil, surface water, sediment and groundwater samples. Quantitative baseline risk assessments were conducted for each site assuming exposures to current base workers and to hypothetical future site workers under a commercial/light industrial scenario. The future use scenario assumed that Big Lake and Little Lake would be developed for recreational uses.

An environmental monitoring program was conducted by Montgomery Watson in 1995 and 1996 and the

Final Comprehensive Analytical Report (CAR) (Montgomery Watson, 1996, AR0132) was prepared to summarize the analytical data collected to date. The results of all sampling and environmental investigations were included for all media investigated to date at the seven sites. The results were used to assess the migration of contaminants within the environment, trends in data over time and the level of risk posed by site contaminants to humans and the environment. The conclusions in the report were used to prepare decision documents for seven sites.

Locations of the ten sites included in this FYR are shown on Figure 2. Site descriptions and results of previous investigations are summarized below.

3.3.1 Past Base Landfill, LF001

The Past Base Landfill (LF001) is located on a southeastward dipping slope near the southeastern comer of Dobbins ARB. The site area is shown on Figure 3. Domestic type refuse and some industrial wastes including waste oil and solvents, AVGAS sludge, paints and thinners, and asbestos-lined brake pads were reportedly disposed at this location from the 1940s until it was officially closed in 1974. An abandoned, open borrow pit excavation is also located at the site. Unauthorized dumping of yard waste, construction and building demolition debris, concrete chunks, and asphalt paving reportedly occurred at the site between 1974 and 1980.

A review of historical analytical results revealed the presence of metals (antimony, chromium, copper, and thallium) in both surface and subsurface soil samples at concentrations that exceeded Georgia Type 3

Risk Reduction Standards (RRS3). Antimony, arsenic, beryllium, lead, thallium, and cadmium have been detected in groundwater samples above RRS3. Furthermore, volatile organic compounds (VOC)

(including trichloroethene [TCE], 1,2-dichloropropane, 1,1,2,2-tetrachloroethene, 1,2-ethylene dibromide, and vinyl chloride) as well as pesticides (including 4,4-dichlorodiphenyldichloroethane [DDD] and dieldrin) have previously been detected at concentrations that exceeded RRS3. (Shaw, 2009, AR0163)

3.3.2 Past Fire Pit Training Area, FT002

The Past Fire Pit Training Area (FT002) is located south of the main Dobbins ARB runway and just east of the northern boundary of AFP6. The site area is shown on Figure 4. FT002 was used for fire training activities performed by base personnel on surplus and/or waste POL products. FT002 consisted of an unlined earthen pit measuring approximately 100 square feet by 4 feet deep. Waste POLs and some mixed solvents were dumped into the pit and ignited during training exercises. Prior to 1969, protein foam was used to extinguish fires. Between 1969 and 1974, Aqueous Film-Forming Foam (AFFF) was used. AFFF contains non-corrosive, biodegradable fluorocarbon surfactants with foam stabilizers. In addition, water was used to extinguish the fire. Water was obtained from a 10 to 12 foot deep holding pond located next to the training area. Excess water from the fire training area flowed into an unnamed creek located west of the site. After fire training activities ceased at the site, it was re-graded and paved. The site is presently used as an equipment storage area and engine power test pad.

Historical analytical results reveal that only metals (antimony, arsenic, beryllium, cobalt, thallium, and vanadium) have been detected in soil samples at concentrations exceeding RRS3. Additionally, a single

VOC (TCE) and one metal (cadmium) were previously detected above RRS3 in groundwater. (Shaw, 2009, AR0163)

3.3.3 Present Fire Pit Training Area, FT003

The Present Fire Pit Training Area (FT003) is located north of the runway adjacent to Big Lake. The site area is shown on Figure 5. FT003 was built in 1974 after FT002 was no longer in use. Fuels with less than

10 percent contamination were used, with approximately 400-500 gallons of fuel consumed during each exercise. The facility consists of a concrete-lined burn pit with a 2,500 gallon tank for fuel storage.

During both its period of operation and since, runoff from the burn pit has been collected in a sump and conveyed to an oil/water separator (OWS) before being treated at the Industrial Waste Treatment Plant at

AFP6. During fire training activities, fuel was delivered to the site by truck and pumped directly into the pit or stored in aboveground storage tanks (ASTs), which have since been removed. No hazardous wastes were known or suspected of having been buried or disposed here.

Historical analytical results reveal that semi-volatile organic compounds (SVOC), primarily polynuclear aromatic hydrocarbons (PAHs) and four metals (beryllium, selenium, thallium, and zinc) were detected in soil at concentrations that exceeded RRS3. Groundwater analytical results reveal that VOCs (including benzene, toluene, and ethylbenzene), SVOCs (naphthalene), and one metal (cadmium) have exceeded

RRS3 for groundwater, but decreased over time during sampling at the site. (Shaw, 2009, AR0163)

3.3.4 Big Lake, OT004

The Big Lake (OT004) site is located north of the Dobbins ARB runway. The site area is shown on

Figure 6. The lake is approximately 7 acres in size and was constructed in 1907 as a backup water source for the city of Marietta. The lake is approximately 15 feet in depth at its deepest point adjacent to the rock and concrete dam at its southeastern end. Surface water from the central part of Dobbins ARB flows into the lake, including three streams draining portions of AFP6. One stream drains a portion of AFP6 and flows east past two IRP sites (DP005 and DP006) before emptying into Big Lake. A subsurface drain system intercepting a groundwater contaminant plume at AFP6 is reported to discharge to one of Big

Lake’s tributaries. Outfall from the lake discharges to a tributary of Rottenwood Creek, which flows to the Chattahoochee River.

Two metals (lead and thallium) and the pesticide dieldrin, have been detected in groundwater samples at concentrations that exceeded RRS3; VOCs and SVOCs were not detected in groundwater samples.

Several VOCs were detected in surface water samples collected in 1989 but not in samples collected in

1995 and 1996. The only pesticide detected in surface water was dieldrin. Several total metals (including arsenic, chromium, lead, mercury and zinc) exceeded the USEPA Water Quality Criteria for human health, and freshwater aquatic life at the site. Sediment samples collected in 1996 contained several

PAHs, pesticides and polychlorinated biphenyls (PCBs), and metals above National Oceanic and

Atmospheric Administration (NOAA) screening levels. Fish tissue samples were collected from Big Lake in May 1996 and were analyzed for PAHs, pesticides, PCBs and metals; three inorganic metals analytes

(mercury, selenium and zinc) and several pesticides (alpha- and gamma-chlordane; 4,4’-dichlorodiphenyldichloroethene (DDE), 4,4’-DDD, and 4,4’-dichlorodiphenyltrichloroethane (DDT);

dieldrin; and heptachlor epoxide) were detected in the tissue samples. The potential human health risks and ecological impacts of analytes detected in sediment and fish tissue were quantified in a Human Health

Risk Assessment (HHRA) and an Ecological Risk Assessment (ERA) for the site. (Shaw, 2009, AR0163)

3.3.5 AVGAS Sludge Burial Site A, DP005

AVGAS Sludge Burial Site A (DP005) is a former storage and handling facility for aviation fuels located northwest of the POL bulk fuel tank farm; the POL area within DP005 has been in use since the 1940s.

The site area is shown on Figure 7. Tank sludge generated when cleaning the fuel tanks was reported to have been buried in shallow pits adjacent to the tanks through 1973. Soil and groundwater samples were collected in 1988. Metals and aromatic hydrocarbons were detected in soil indicating a release to the environment, and groundwater sampling indicated contaminant migration to the northeast and east. The groundwater gradient at the site is in the direction of a small stream that borders the site to the northeast.

Six 25,000-gallon USTs were removed in 1991. The tanks had been anchored to a concrete slab about 14 feet below ground surface (bgs) that was left in place. No free petroleum product was observed during the

UST removal. The stockpiled soil was determined to be nonhazardous, returned to the tank excavation and covered with clean backfill. The site contains two JP-8 ASTs located in a concrete secondary containment basin, one 84,000 gallon and the other 210,000 gallons and is actively used for fueling.

Historical analytical results indicated VOCs and metals were detected above regulatory standards in soil and groundwater. Two VOCs (benzene and total xylenes) and several metals (arsenic, beryllium, cobalt, mercury, selenium, thallium, vanadium and zinc) were detected above RRS3 standards in soil. In groundwater samples, benzene exceeded RRS3 in five of nine wells sampled between 1989 and 1996;

ethyl benzene and toluene only exceeded RRS3 at well D5-W47, located adjacent and downgradient of the UST excavation. Free-phase petroleum was also observed at D5-W47. Surface water and sediment samples collected from the small stream bordering the site contained chlorinated VOCs, primarily TCE, considered to originate at AFP6 rather than DP005. (Shaw, 2009, AR0163)

3.3.6 AVGAS Sludge Burial Site B, DP006

The AVGAS Sludge Burial Site B (DP006) is located in the area of the present Georgia Army National

Guard, Buildings 554 and 555, south of Atlantic Avenue and across from DP005. The site area is shown on Figure 8. Diesel and gasoline USTs, as well as a single dispenser island, were previously located near where the southern side of Building 554 currently stands. A small quantity of fuel tank sludge was reportedly buried at the site; however, no evidence of buried sludge was identified during investigation of the site. Only bottles and debris were uncovered during construction activities.

Several metals (antimony, arsenic, beryllium, chromium, cobalt, nickel, thallium, vanadium, and zinc) were detected above RRS3 for soil; however, these concentrations may be naturally occurring based on other soil sample results at Dobbins ARB.

Groundwater samples were re-collected in 1995 and 1996 after samples collected in 1989 and 1990 exceeded RRS3 criteria for several analytes. The 1995 and 1996 samples did not contain VOCs at concentrations above RRS3 levels, naphthalene was the only SVOC above RRS3, and cadmium and lead were the only metals to exceed RRS3. (Shaw, 2009, AR0163)

3.3.7 Little Lake, OT007

Little Lake (OT007) is a small man-made lake located north of the intersection of Atlantic Avenue and

Andrews Drive. The lake was constructed in 1910 and is fed by intermittent discharge from springs on the slopes to the northwest and some surface drainage that originates on AFP6 property. The site area is shown on Figure 9.

Groundwater samples were not collected based on absence of contaminants in previous investigations.

Surface water and sediment samples were collected in several sample events from 1985 to 1996. Metals, pesticides, PCBs and SVOCs (primarily PAHs) detected in early sample events were either not present or at lower concentrations in later events. Fish tissue samples collected in 1996 detected metals (mercury and zinc) and pesticides (4,4-DDE and dieldrin) in the tissues. The potential human health risks and ecological impacts of all constituents detected in fish tissues were quantified in a HHRA and ERA for the site. (Shaw, 2009, AR0163)

3.3.8 Former Railroad Car Fuel Transfer Lines, ST008

The Former Railroad Tanker Car Transfer Lines (ST008) consisted of a system of 4-inch and 6-inch diameter gravity flow pipelines used to transport fuel to six 25,000-gallon USTs located at the POL bulk fuel tank farm (DP005). The 4-inch fuel lines had threaded joints and were most likely components of the former off-loading headers. The 6-inch lines contained no threaded joints and had welded pipe joints.

These fuel lines were in use from the early 1950's to the early 1970's. In 1990, during the installation of a backup surface fuel system, a portion of these lines was uncovered and a fuel odor detected. Dobbins

ARB personnel reported that portions of transfer lines may have been previously removed. The site area is shown on Figure 10.

A preliminary assessment and site investigation were conducted in June-July 1997. Aromatic VOCs such as benzene, toluene, isopropylbenzene, and m, p, o-xylenes, slightly exceeded applicable criteria in soil.

Chlorinated VOCs, such as 1,1,2,2-tetrachloroethane and 1,2-dibromo-3-chloropropane were reported at concentrations exceeding applicable or relevant and appropriate requirements (ARARs) in one soil sample, but the results were considered to be associated with the adjacent AFP6 facility and not the former fuel transfer lines at ST008. JP-4 fuel constituents were observed at the groundwater table in the southwestern portion of the site in the vicinity of the former fuel transfer lines (Montgomery Watson, 1997, AR0110).

3.3.9 Barrel Disposal Site, DA011

Approximately 25 barrels were discovered partially buried in soil, asphalt, and concrete rubble near the former Dobbins ARB Landfill (LF001) but outside the official landfill area. The site appears to be independent of the landfill. Barrels at the site are in poor condition (rusted and with multiple cracks and holes) and the initial contents are not known. Trees growing on the site appear to be approximately 35 to

45 years old indicating the barrels were deposited on the site prior to 1984. The site area is shown on

Figure 11.

Soil samples were collected at 10 locations in May 2010. Sampling results indicate a release of benzene, toulene, xylene, butyl-benzyl phthalate, dieldrin, and other pollutants to the soil. Further investigation was recommended for site validation (URS, 2010, AR0112).

3.3.10 Oil/Water Separator 4A, OW504A

Oil/Water Separator 4A (OW504A) was an OWS installed in 1972 on the west side of Building 947, Fuel

Lab, which received waste from the sink in the fuels laboratory. The OWS was constructed of steel with a

3-gallon capacity and a 50-gallon holding tank; it discharged to the sanitary sewer. During removal of the

OWS in September 1998, surface contamination was observed from an OWS overflow; an estimated 10 cubic yards of soil was impacted. The site area is shown on Figure 12.

A soil sample was collected in December 2011 contained hydrocarbon contaminants in diesel and gasoline ranges and various VOCs. OW504A was recommended for validation (AECOM, 2012a, AR0184).

3.4 INITIAL RESPONSE

Response actions were performed at two sites prior to preparation of decision documents.

3.4.1 AVGAS Sludge Burial Site A, DP005

In August 1991, six 25,000-gallon USTs were removed from the area west of the ASTs in the current

POL yard and about 100 feet southwest of the presumed sludge burial pit. The tanks had been anchored to a concrete slab that was left in place about 14 feet bgs. Contaminated soil was identified during removal of the six USTs and associated piping. Twenty-two soil samples were collected in accordance with GA

EPD UST guidelines and analyzed for total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Ten of the samples exceeded the Georgia Underground Storage Tank

(GUST) TPH action level of 500 milligrams per kilogram (mg/kg), and six of the samples exceeded the total BTEX action level of 100 mg/kg. No free petroleum product was observed beneath the tanks or the piping during the UST removal.

Samples of the stockpiled soil were tested using the toxicity characteristic leaching procedure and were found to be nonhazardous. The stockpiled soil was returned to the tank excavation and covered with clean soil. The backfill was mounded to promote surface water runoff and reduce infiltration (Parsons 1995, AR0102). The GUST Management Program was notified that contamination had been discovered at the site and designated the site GA EPD Facility ID No. 9033018.

3.4.2 Former Railroad Car Fuel Transfer Lines, ST008

The transfer lines were excavated and removed in September 1998 (Montgomery Watson, 1999, AR0135). A perpendicular trench in the western portion of the site exposed two 6-inch transfer pipelines located parallel to each other and approximately 1 foot apart. The excavation was extended to the east exposing the 6-inch pipelines; the lines had been previously cut and ended west of the taxiway. Headers from the former tanker car offloading system and three 4-inch transfer pipelines were uncovered during the excavation. The 4- and 6-inch pipeline ran parallel to each other. One of the 6-inch pipelines ran beneath an asphalt road west of the excavation; the section under the road was left in-place, filled with non-shrinking grout, and mechanically capped. The 4-inch pipelines were then uncovered up to the taxiway where the lines were cut, filled with non-shrinking grout, and capped.

Prior to removal, all five pipelines were found to contain residual fuel. The pipelines were inerted with nitrogen gas and elevated/lifted from the excavation and the residual fuel was captured with a vacuum hose. Approximately 310 gallons of fuel was recovered and transported off-site for recycling. The lines were cut, removed from the trench, and placed next to the excavation. The piping was cut into 25-foot sections, cleaned, and transported to a recycling facility. Liquids from the pipeline cleaning were collected, sampled, and transported to a disposal facility.

Post excavation soil samples were collected from the floor of the excavation/trench per GUST guidelines.

Eight samples were initially collected; additional excavation and confirmation sampling was required at two locations. The final analytical results were below the applicable GUST Soil Threshold Levels.

Soil removed from the excavation/trench was field screened using a photoionization detector and segregated for possible use as backfill or for disposal characterization. Composite samples collected from the soil piles adjacent to the excavation only contained low TPH concentrations and the soil was placed back into the excavation. Site restoration activities included refilling, re-grading the excavated area and placement of crushed stone within the fenced parking area; the area outside the fence was re-vegetated with grass seed.

The soil stockpiled for disposal characterization was sampled and classified as nonhazardous petroleum-contaminated soil. Contaminated soil (71 tons) and asphalt (20 tons) were transported off-site for disposal in April 1999 (Montgomery Watson, 1999, AR0135).

In June and July 2000, three direct-push groundwater samples were collected and four monitoring wells were installed and sampled during an investigation designed to fully delineate both free-phase and dissolved-phase petroleum hydrocarbons. Free product was not found at any of these locations

(Montgomery Watson, 2001a, AR0158).

Additional field sampling was performed in October 2001 to vertically delineate BTEX contamination at one location in accordance with the GA EPD's request. Samples did not exceed applicable limits.

(Montgomery Watson, 2001b, AR0160). Correspondence from GA EPD UST Management Program dated 7 November 2001 stated NFA was required for the release at ST008. Dobbins ARB was requested to submit documentation that the associated monitoring wells were destroyed. The wells were properly abandoned and documented in a report submitted to GA EPD on 29 January 2002 (Montgomery Watson, 2002, AR0161).

3.5 BASIS FOR TAKING ACTION

3.5.1 Risk Assessment

The quantitative baseline risk assessment presented in the RI Report (Parsons, 1995, AR0102) characterized the potential risks to human health (HHRA) posed by constituents detected at each of the

IRP sites. The additional, qualitative HHRA presented in the CAR (Montgomery Watson, 1996, AR0132), included comparison of data reported in the RI Report and additional sampling results from 1995 and

1996, to establish whether additional contaminants of potential concern (COPCs) or higher concentrations of COPCs were present that would impact the results of the quantitative HHRA. The results indicated that additional data were not likely to change the HHRA findings in the RI Report.

The HHRA evaluated the contaminants detected, potential exposure pathways between constituents, and human receptors and the potential human health risks posed by these exposures. All constituents detected in the various environmental media during multiple sampling investigations (Parsons, 1995 and

Montgomery Watson, 1996) were evaluated to determine COPCs for analysis in the risk assessment.

Selection of COPCs was based on frequency of detection, comparison with laboratory and field blanks, and comparison with background concentrations.