EPA/ROD/R04-04/663
2004
EPA Superfund
Record of Decision:
ROBINS AIR FORCE BASE (LANDFILL #4/SLUDGE LAGOON)
EPA ID: GA1570024330
OU 01, 03
HOUSTON COUNTY, GA
09/30/2004
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FINAL
RECORD OF DECISION (ROD)
FOR THE NATIONAL PRIORITIES LIST (NPL) SITE, OPERABLE
UNITS (OUs) 1 AND 3
Environmental Management Directorate
Robins Air Force Base, Georgia
September 2004
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FILE
FINAL
RECORD OF DECISION (ROD) FOR
THE NATIONAL PRIORITIES LIST (NPL) SITE,
OPERABLE UNITS (OUs) 1 AND 3
FOR
WARNER ROBINS AIR LOGISTICS CENTER
ROBINS AFB, GEORGIA
CONTRACT NO. F09650-00-D-0012, DELIVERY ORDER NO. 5055
EARTH TECH PROJECT NO. 75279
Prepared for:
Environmental Management Directorate
Robins Air Force Base, Georgia
Prepared by:
Earth Tech, Inc.
September 2004
^_Eric I/Stern, P.O.
Delivery Order Manager/Technical L6ad
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CERTIFICATION
FINAL
RECORD OF DECISION (ROD) FOR
THE NATIONAL PRIORITIES LIST (NPL) SITE,
OPERABLE UNITS (OUs) 1 AND 3
PREPARED FOR
ENVIRONMENTAL MANAGEMENT DIRECTORATE
WARNER ROBINS AIR LOGISTICS CENTER
ROBINS AIR FORCE BASE, GEORGIA
I certify that I am a qualified groundwater scientist who has received a baccalaureate or post-graduate
degree in natural sciences or engineering, and have sufficient training and experience in groundwater
hydrogeology and related fields, as demonstrated by state registration and completion of accredited
university courses, that enable me to make sound professional judgments regarding groundwater
monitoring and contaminant fate and transport. I further certify that this report was prepared by myself or
by a subordinate working under my direction.
J. Stern,
Sehier Hydrogeologist
Georgia Reg. No. 001518
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
TABLE OF CONTENTS
Section Page No.
1.0 DECLARATION FOR THE RECORD OF DECISION 1
1.1 SITE NAME AND LOCATION 1
1.2 STATEMENT OF BASIS AND PURPOSE 1
1.3 ASSESSMENT OF SITE 1
1.4 DESCRIPTION OF THE SELECTED REMEDY 2
1.4.1 Selected Remedy For Operable Unit 1 2
1.4.2 Selected Remedy for Operable Unit 3 3
1.5 STATUTORY DETERMINATIONS 4
1.6 DATA CERTIFICATION CHECKLIST 4
1.7 AUTHORIZING SIGNATURES AND SUPPORT AGENCY ACCEPTANCE OF
REMEDY 5
2.0 THE DECISION SUMMARY 6
2.1 SITE NAME, LOCATION, AND DESCRIPTION 6
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES 6
2.2.1 Activities That Have Led to Current Problems 6
2.2.2 Federal, State, and Local Site Investigations and Remedial Actions Conducted
to Date Under CERCLA and Under Other Environmental Authorities 7
2.2.3 History of Comprehensive Environmental Response, Compensation, and
Liability Act Enforcement Activities 9
2.3 COMMUNITY PARTICIPATION 9
2.4 SCOPE AND ROLE OF OPERABLE UNIT 10
2.5 SITE CHARACTERISTICS 13
2.5.1 Conceptual Site Model 13
2.5.2 Site Overview 14
2.5.3 Surface and Subsurface Features 14
2.5.4 Sampling Strategy 14
2.5.5 Sources of Contamination 14
2.5.6 Type of Contamination and Affected Media 15
2.5.7 Location of Contamination and Potential Routes of Migration 16
2.5.8 Hydrogeology 17
2.6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USES 18
2.7 SUMMARY OF SITE RISKS 18
2.7.1 Summary of Risk from OU1 19
2.7.2 Summary of Risk from OU3 20
2.7.2.1 Summary of Previous Human Health Risk Assessments for OU3 20
2.7.2.1.1 Identification of Chemicals of Concern 20
2.7.2.1.2 Exposure Assessment 21
2.7.2.1.3 Toxicity Assessment 22
2.7.2.1.4 Risk Characterization 24
2.1.2.2 Summary of Previous Ecological Risk Assessments for OU3 28
2.7.2.3 Summary of Current Risk from OU3 29
2.8 REMEDIAL ACTION OBJECTIVES 30
2.9 DESCRIPTION OF ALTERNATIVES 31
2.9.1 Description of Remedy Components 32
2.9.2 Common Elements and Distinguishing Features of Each Alternative 35
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
TABLE OF CONTENTS (Continued)
Section Page No.
2.10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 39
2.11 PRINCIPAL THREAT WASTES 40
2.12 SELECTED REMEDY 40
2.12.1 Operable Units 1 and 3 Land Use Controls 40
2.12.2 Summary of Rationale for the Selected Remedy 44
2.12.2.1 Operable Unit 1 (LF04 and WP14 Sludge Lagoon) 44
2.12.2.2 Operable Unit 3 (Groundwater) 44
2.12.3 Description of Selected Remedy 45
2.12.3.1 Operable Unit 1 (LF04 and WP 14 Sludge Lagoon) 45
2.12.3.2 Operable Unit 3 (Groundwater) 45
2.12.4 Summary of Estimated Remedy Costs 46
2.12.5 Expected Outcomes of the Selected Remedy 47
2.13 STATUTORY DETERMINATIONS 48
2.13.1 Protection of Human Health and the Environment 48
2.13.2 Compliance with Applicable or Relevant and Appropriate Requirements 49
2.13.3 Cost Effectiveness 49
2.13.4 Use of Permanent Solutions and Alternative Treatment Technologies (or
Resource Recovery Technologies) to the Maximum Extent Practicable 49
2.13.5 Preference for Treatment as a Principal Element 50
2.13.6 FiveYear Review Requirements 50
2.14 DOCUMENTATION OF SIGNIFICANT CHANGES FROM PREFERRED
ALTERNATIVE OF PROPOSED PLAN 51
2.14.1 Operable Unit 1 51
2.14.2 Operable Unit 3 51
3.0 RESPONSIVENESS SUMMARY 52
4.0 REFERENCES 54
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
LIST OF TABLES
Table No.
1 Prevalent Chemicals Found in Source Area OU1 During Remedial Investigation
2 Summary of Chemicals of Concern for OUS Groundwater
3 Current Concentrations for Chemicals of Concern for OUS Groundwater Comparison to
MCLs and Historic Concentrations
4 Summary of Chemicals of Concern and Medium-Specific Exposure Point Concentrations
- Groundwater
5 Cancer Toxicity Data - Oral/Dermal
6a Cancer Toxicity Data - Inhalation (from BRA Reports)
6b Additional Cancer Toxicity Data - Inhalation
7a Non-Cancer Toxicity Data - Oral/Dermal (from BRA Reports)
7b Additional Non-Cancer Toxicity Data - Oral/Dermal
8 Additional Non-Cancer Toxicity Data - Inhalation
9 Risk Characterization Summary - Carcinogens and Non Carcinogens, Future On-Site
Adult Resident - Groundwater
10 Summary of Final Chemicals of Concern in Groundwater
11 Comparative Analysis of Alternatives for OUS
12 Cost Estimate Summary for the OUS Selected Final Remedy (10 year and 30 year
Scenarios)
13 Decision Matrix for Comparison of Alternatives
14 Description of ARARs for Selected Remedy
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
LIST OF FIGURES
Figure No.
1 Site Location Map
2 Landfill No.4 And WP14 Sludge Lagoon (NPL Site) Map
3 Landfill No.4 And WP14 Sludge Lagoon Capping System
4 Groundwater Extraction System
5 Conceptual Site Model
6 Regional Geologic Cross Section
7 1998 TCE Concentrations Surficial Aquifer
8 2003 TCE Concentrations Surficial Aquifer
9 1989 TCE Concentrations Quaternary Alluvial Aquifer
10 1998 TCE Concentrations Quaternary Alluvial Aquifer
11 2003 TCE Concentrations Quaternary Alluvial Aquifer
12 Historical TCE Concentrations Quaternary Alluvial Aquifer
13 1998 TCE Concentrations Upper Providence
14 2003 TCE Concentrations Upper Providence
15 Historical TCE Concentrations Upper Providence
16 1998 TCE Concentrations Lower Providence
17 2003 TCE Concentrations Lower Providence
18 1998 Lead Concentrations Surficial Aquifer
19 2003 Lead Concentrations Surficial Aquifer
20 1989 Lead Concentrations Quaternary Alluvial Aquifer
21 1998 Lead Concentrations Quaternary Alluvial Aquifer
22 2003 Lead Concentrations Quaternary Alluvial Aquifer
23 Land Use Control Area
LIST OF APPENDICES
Appendix
A Review of Inorganic Chemicals of Concern (Nickel and Chromium)
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
AFB
ARAR
BEHP
BRA
GDI
CERCLA
COC
CSM
EHRAV
EPC
FFA
GAEPD
GPM
GWTS
HEAST
HI
HQ
IRIS
IROD
IRP
ISA
IWTP
LF04
LUC
MCL
MNA
NAPL
NCP
NPDES
NPL
O&M
OU
PAH
PP
RAO
RCRA
RFD
RI/FS
ROD
SF
SHRTSC-NCEA
SPHEM
SVE
TCE
USAF
LIST OF ACRONYMS
Air Force Base
Applicable Or Relevant And Appropriate Requirement
Bis (2-Ethylhexyl) Phthalate
Baseline Risk Assessment
Chronic Daily Intake
Comprehensive Environmental Response, Compensation, And Liability Act
Chemicals of Concern
Conceptual Site Model
Electronic Handbook Of Risk Assessment Values
Exposure Point Concentration
Federal Facilities Agreement
Georgia Environmental Protection Division
Gallons Per Minute
Groundwater Treatment System
Health Effects Assessment Summary Tables
Hazard Indices
Hazard Quotient
Integrated Risk Information System
Interim Record of Decision
Installation Restoration Program
Initial Screening of Alternatives
Industrial Waste Treatment Plant
Landfill Number 4
Land Use Control
Maximum Contaminant Level
Monitored Natural Attenuation
Non-Aqueous Phase Liquid
National Oil and Hazardous Substances Pollution Contingency Plan
National Pollution Discharge Elimination System
National Priorities List
Operations and Maintenance
Operable Unit
Polynuclear Aromatic Hydrocarbon
Proposed Plan
Remedial Action Objective
Resource Conservation And Recovery Act
Reference Dose
Remedial Investigation/Feasibility Study
Record of Decision
Slope Factor
Superfund Health Risk Technical Support Center National Center For
Environmental Assessment
Superfund Public Health Evaluation Manual
Soil Vapor Extraction
Trichloroethene
United States Air Force
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
LIST OF ACRONYMS (Continued)
US EPA United States Environmental Protection Agency
VOC Volatile Organic Compound
WQS Water Quality Standard
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
1.0 DECLARATION FOR THE RECORD OF DECISION
1.1 SITE NAME AND LOCATION
National Priorities List Site (NPL Site) (formerly referred to as Zone 1), Robins Air Force Base (AFB)
Operable Unit 1 (OU1) - Landfill No. 4 (LF04) and the WP14 Sludge Lagoon (Sludge Lagoon) Source
Units
Operable Unit 3 (OUS) - Groundwater contaminated by OU1
Warner Robins, Houston County, Georgia
National Superfund Identification Number: GA15 700243 30
Robins AFB is located approximately 18 miles south of Macon, Georgia.
1.2 STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) is being issued by the United States Air Force (USAF), which is the lead
agency for remedial activities at Robins AFB. The remedy was selected by the USAF in conjunction with
the United States Environmental Protection Agency (US EPA) - Region IV with the concurrence of the
Georgia Environmental Protection Division (GA EPD).
This ROD presents the selected remedial action for addressing the NPL Site OUs 1 and 3 of the Robins
AFB Site, developed in accordance with the Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) as amended by the Superfund Amendments and Reauthorization Act, and to
the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP)
(US EPA, 1990b). This decision is based on the Administrative Record file for this site.
1.3 ASSESSMENT OF SITE
The response action selected in this ROD is necessary to protect the public health or welfare or the
environment from actual or threatened releases of hazardous substances into the environment. Figure 1
presents a site location map that shows the LF04 and Sludge Lagoon source unit areas at the NPL Site in
relation to Robins AFB.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
1.4 DESCRIPTION OF THE SELECTED REMEDY
The remedial action objectives at this NPL site were to (1) perform Interim Actions at OU1 to mitigate
impact to groundwater; (2) perform an Interim Action for groundwater (OUS) that provided for
containment of contaminated groundwater and prevented further migration, and (3) perform a final action
for OUs landS.
The source material (OU1) has undergone several physical and chemical treatments in order to reduce the
principal threats. The sludge lagoon underwent volatilization and solidification to immobilize the
principal threat wastes. The rest of the landfill waste mass was not treated due to costs and the
uncertainty of contents. Land use controls (LUCs) are necessary for OU1 since containment and not
treatment was selected as the remedy. For OUS groundwater, there are no principal threat wastes.
1.4.1 Selected Remedy For Operable Unit 1
The Selected Remedy for OU1 (LF04 and the Sludge Lagoon) as described in the Interim Record of
Decision (IROD) (Installation Restoration Program (IRP), 1991) and the Feasibility Study (FS)
(Earth Tech/Rust E&I, 1999a) includes the following actions that have already been completed:
Initial clay capping of the Sludge Lagoon with a clayey sand cover;
In situ volatilization of the Sludge Lagoon waste mass;
Excavation of the Sludge Lagoon waste mass and solidification;
LF04 cover renovation using geosynthetic fabric and clay liner;
Installation of gas collection system at LF04;
Construction of a new cover over LF04 and the Sludge Lagoon;
Construction of a run-on diversion structure around LF04;
Installation of a groundwater extraction system at LF04;
Installation of a leachate collection system at LF04; and
Institutional controls for access to site.
Since the exposure pathways to the waste materials in OU1 have been eliminated, and further
groundwater impact to OUS (groundwater) has been mitigated, no additional remedial actions will be
undertaken. This decision has been approved by the agencies in the Initial Screening of Alternatives
(ISA) document, which recommends no further action for OU1 (Robins AFB, 1998). The final remedy
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
for OU1 is containment through maintenance of the cap as well as LUCs limiting site use and activity.
As the lead agency, Robins AFB will be responsible for implementing and enforcing all institutional
controls/LUCs.
1.4.2 Selected Remedy for Operable Unit 3
The Selected Remedy for the OUS (groundwater) includes the following:
Optimization of the current OUS Interim Action groundwater extraction system by evaluating the
efficiency and effectiveness of the OUS groundwater extraction system. When the evaluation of
the data for two groundwater sampling events indicate that the continued operation of the system
is less efficient and effective than monitored natural attenuation (MNA), documentation will be
provided by the Air Force to the US EPA and GA EPD to justify the technical decision for
turning off the groundwater extraction system and transitioning to MNA. The supporting data
may include the analytical results, isoconcentration maps, contaminant trend analyses,
groundwater extraction rate data, contaminant mass removal data, system operating costs, and
revised groundwater and transport modeling, as applicable. The supporting data will sufficiently
document the groundwater treatment system's efficiency and effectiveness. This evaluation,
subject to the US EPA and GA EPD review and approval, will allow for deactivating the OUS
groundwater extraction system and transitioning to MNA when it is determined that MNA is the
most appropriate remedial strategy;
Treatment of the extracted groundwater in the Groundwater Treatment System (GWTS);
Discharge the treated groundwater (effluent) to the Ocmulgee River at a preexisting National
Pollution Discharge Elimination System (NPDES) permitted outfall, in accordance with the
substantive standards under that permit;
Annual monitoring to verify the reduction in contaminant concentrations and to monitor the
effectiveness of natural attenuation mechanisms; and
Limiting the future use of the site (land and groundwater) through institutional controls/LUCs.
As the lead agency, Robins AFB will be responsible for implementing and enforcing all institutional
controls/LUCs.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
1.5 STATUTORY DETERMINATIONS
The remedies for OU1 and OUS are protective of human health and the environment, comply with
Federal and State requirements that are applicable or relevant and appropriate to the remedial action, are
cost-effective, and utilize permanent solutions and alternative treatment technologies to the maximum
extent practicable. Although treatment has occurred in select source areas (Sludge Lagoon) of LF04, the
OU1 remedy does not attain the statutory preference for treatment as a principal element of the remedy
because there is no cost-effective treatment technology for a 45-acre landfill. However, the remedy
selected involves containment of the source area, which is the US EPA presumptive remedy for landfills.
The remedy for OUS satisfies the statutory preference for treatment as a principal element of the remedy
that permanently and significantly reduces the toxicity, mobility, and volume of hazardous substances,
pollutants, or contaminants.
Because the remedies for OU1 and OUS will 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 conducted no less often than every five years after initiation of remedial action under this ROD to
ensure that the remedy continues to be protective of human health and the environment.
1.6 DATA CERTIFICATION CHECKLIST
The following information is included in the Decision Summary section of this ROD. Additional
information can be found in the Administrative Record file at Robins AFB for the NPL Site.
Chemicals of concern (COCs) and their respective concentrations (see starting on page 15
[Section 2.5.6] and Tables 1, 2, and 3).
COCs in the baseline risk assessments (BRAs) (see starting on page 21 [Section 2.7.2.1.2] and
Table 4).
Baseline risk level represented by the COCs (see starting on pages 19 and 20 [Sections 2.7.1 and
2.7.2], starting on page 29 [Section 2.7.2.3], and Table 9).
Cleanup levels established for COCs and the basis for these levels (see starting on page 29
[Section 2.7.2.3] and Table 2).
How source materials constituting principal threats are addressed (see starting on page 40
[Section 2.11]).
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) I and 3
Robins Air Force Base
Warner Robins, Georgia
Current and reasonably anticipated future land use assumptions and current and potential future
beneficial uses of groundwater used in the BRA and ROD (see starting on page 18 [Section 2.6],
starting on page 21 [Section 2.7.2.1.2], and Table 11).
Potential land and groundwater use that will be available at the NPL Site as a result of the
Selected Remedy (see starting on page 47 [Section 2.12.5]).
Estimated capital, annual operations and maintenance (O&M), escalated costs, present worth
costs, and the number of years over which the remedy cost estimates are projected (see starting on
page 46 [Section 2.12.4] and Tables 11 and 12).
Key factor(s) that led to selecting the remedy (see starting on page 4 4 [Section 2.12.2] and Tables
11, 13, and 14).
1.7 AUTHORIZING SIGNATURES AND SUPPORT AGENCY ACCEPTANCE OF
REMEDY
The following signatures below signify that all parties agree to the contents of this ROD and the Selected
Remedy.
. Reyiiglds \^___
Lieutenant General, USAF
Vice Commander, Air Force Materiel Command
Winston A. Smith
Director, Waste Management Division
United States Environmental Protection Agency
Carol A"Couch, Ph.D.
Director
Georgia Environmental Protection Division
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.0 THE DECISION SUMMARY
2.1 SITE NAME, LOCATION, AND DESCRIPTION
Name and Location: NPL Site, Robins AFB
OU1, LF04 and the Sludge Lagoon Source Units
OUS, Groundwater Contaminated by OU1
Warner Robins, Houston County, Georgia
National Superfund Identification Number: GA15 700243 3 0
Lead and Support Agencies: Lead: USAF, Support: US EPA and GA EPD.
Source of Cleanup Monies: The funding for cleanup of the NPL Site is the Air Force
Environmental Restoration Account, which are monies designated by the United States Congress
specifically for the IRP.
Site Type: Landfill
Site Description: The NPL Site at Robins AFB consists of two IRP sites. The two IRP sites are
LF04 and the Sludge Lagoon. The LF04 source unit (OU1) is a 45-acre landfill. The Sludge
Lagoon source unit (OU1) was a 1.5-acre unlined lagoon (Figure 2). The NPL Site was initially
divided into three OUs. OU1 is defined as the LF04 and the Sludge Lagoon source units. OU3 is
defined as the groundwater contaminated by OU1 (the LF04 and the Sludge Lagoon source
units). In 2003, the US EPA, the GA EPD, and Robins AFB agreed that the adjacent wetlands
area, formerly known as OU2, did not contain contamination from the LF04 and the Sludge
Lagoon source units (OU1) and, therefore, would not be addressed under the current Federal
Facilities Agreement (FFA) (US EPA, 2003b). The former OU2 wetlands area is being addressed
under the Resource Conservation and Recovery Act (RCRA) delegated to the State of Georgia.
Therefore, this ROD addresses only OU1 and OU3.
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.2.1 Activities That Have Led to Current Problems
Robins AFB has generated various types of solid wastes over the years of operation, including refuse and
hazardous wastes. The LF04 source unit was operated from 1965 to 1978 for disposal of general refuse
and industrial wastes (Figure 2). The Sludge Lagoon source unit was used from 1962 to 1978 for disposal
of IWTP sludges (Figure 2). Sludge from the IWTPs contained phenols, oils, and other wastes.
Electroplating sludge from IWTP No. 2 contained heavy metals and cyanide. Miscellaneous industrial
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
wastes, such as solvents, cleaners, paint removers, hydraulic fluids, and oils, were also placed in the
lagoon. The Sludge Lagoon was closed in 1978 by capping with a clayey sand cover approximately five
feet thick.
2.2.2 Federal, State, and Local Site Investigations and Remedial Actions Conducted to Date
Under CERCLA and Under Other Environmental Authorities
Following a survey of the Base in 1982, former disposal areas were grouped into eight zones that were
based primarily on location and type of disposal activity. The NPL Site (formerly referred to as Zone 1),
which includes the LF04 and the Sludge Lagoon sources units (OU1), was considered to have the highest
potential for migration of hazardous substances and, as a result, was placed on the CERCLA NPL by the
US EPA in 1987. Soils in LF04 and the Sludge Lagoon were found to contain constituents at
concentrations sufficient to leach to the groundwater at levels higher than the maximum contaminant level
(MCLs). Due to this impact, Interim Actions were conducted for OU1 and OUS.
In August 1996, Robins AFB completed remediation of the Sludge Lagoon as an Interim Action where
the waste mass was first treated by in-situ volatilization then excavated and solidified. In addition, a
geosynthetic fabric and clay liner were installed over the entire surface area of OU1 (LF04 and the Sludge
Lagoon).
In September 1998, a soil cover renovation was completed for LF04. The renovated soil cover installed
over LF04 also extends over the Sludge Lagoon. The design of the landfill cover complied with the cover
requirements of the IROD and consists of the following (Figure 3) (Environmental Chemical Corporation,
1997):
Site grading soil
Gas collection system
Geosynthetic clay liner
Drainage layer system
Topsoil
The remedial action objectives (RAOs) for OUS (groundwater) are containment and remediation of
contaminants to the MCLs as defined in Table 2 of this ROD. As part of the Interim Action at LF04, six
groundwater recovery wells (RW1 through RW6) were installed along the northeastern boundary of LF04
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
and the Sludge Lagoon (Figure 4). The Interim Action also included the construction and operation of a
groundwater treatment plant. The treated groundwater ultimately discharges to the Olcmulgee River
basin under a preexisting NPDES permit. The recovery wells have operated in order to capture elevated
levels of contaminants while allowing residual contaminants, not feasibly captured by the OUS
groundwater extraction system, to be reduced by natural attenuation. Due to lack of detected
contamination in recovery well RW1, the operation of this well was discontinued in February 1999 with
prior regulatory approval (US EPA and GA EPD). The decision to deactivate the recovery well was
approved by the GA EPD in an e-mail forwarded on 10 February 1999 and by the US EPA verbally at the
NPL Site meeting held on 10 February 1999.
Groundwater modeling was performed to determine the optimum flow rate and location of the extraction
wells as described in the Feasibility Study (Earth Tech/Rust Environment & Infrastructure, 1999a).
During the NPL Site Team Meeting held on 10 January 2002, the US EPA and the GA EPD confirmed
that Robins AFB could proceed with implementation of the Draft ROD (Earth Tech, 2000a). Operation
of recovery wells RW2, RW3, and RW6 was discontinued on 14 May 2002 in accordance with the OU1
and OUS Draft ROD. As part of the agreement, larger pumps were placed in both recovery wells RW4
and RW5 to increase the rate of withdrawal from approximately 30 gallons per minute (gpm) to 50 gpm.
These recovery wells are currently rehabilitated periodically to ensure optimum performance of the
system.
Robins AFB has initiated a number of corrective measures at the NPL Site to limit or mitigate the impacts
to OUS (groundwater) including the construction of a run-on diversion structure around LF04 and the
installation of a leachate collection system around the northern periphery of LF04, which began operation
in October 1997. The leachate collection system is referred to as the "LF04 toe drain." There are four
leachate pump stations within the LF04 toe drain. One of the pump stations, LF4PS3, was shut down as
approved by the US EPA and the GA EPD at the monthly NPL Site meeting held on 17 March 1999. The
three remaining pump stations (LF4PS1, LF4PS2, and LF4PS4) operated until 14 May 2002 and were
subsequently shut down, thereby decommissioning the LF04 toe drain, in accordance with the OU1 and
OUS Draft ROD (Earth Tech, 2000a).
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.2.3 History of Comprehensive Environmental Response, Compensation, and Liability Act
Enforcement Activities
The US EPA placed the site on the CERCLA NPL in 1987 (National Superfund Identification Number:
GA1570024330). In June 1989, Robins AFB entered into a FFA with the US EPA and the GA EPD to
establish a procedural framework and a schedule for developing, implementing, and monitoring
appropriate response actions at the NPL Site in accordance with CERCLA, the NCP, Superfund guidance
and policy, and the Georgia Hazardous Waste Management Act.
From 1991 to 1994, there were several disputes concerning the applicable or relevant and appropriate
requirements (ARARs) for OUS (groundwater) at the NPL Site. These disputes eventually led to the
February 28, 1994, Dispute Resolution of ISA for OUS. The ISA dispute resolution resulted in defining
the groundwater point of compliance as Hannah Road (Figure 1), and the interim remedial goals as
US EPA MCLs and nonzero maximum contaminant level goals for the Blufftown and Providence
aquifers and as Georgia Ambient Water Quality Criteria for the Quaternary alluvial aquifer.
In 2003, the US EPA, the GA EPD, and Robins AFB agreed that the adjacent wetlands area, formerly
known as OU2, did not contain contamination from the LF04 and the Sludge Lagoon source units (OU1)
and, therefore, would not be addressed under the current FFA (US EPA, 2003b). The former OU2
wetlands area is now being addressed under the RCRA regulations delegated to the State of Georgia.
2.3 COMMUNITY PARTICIPATION
The Remedial Investigation/Feasibility Study (RI/FS) Report and Proposed Plan (PP) for OU1 and OUS,
Robins AFB, Georgia, were made available to the public in January 2000 (Earth Tech/Rust E&I, 1999a
and Earth Tech/Rust E&I, 1999b, respectively). These unabridged documents are part of the FFA
Administrative Record File, which is available for review by the public at the following location:
Warner Robins Air Logistics Center Environmental Management Directorate (WR-ALC/EM)
455 Byron Street, Suite 465
Robins AFB, Georgia 31098-1646
(478)926-1197
Selected "final" documents including the RI/FS and PP are available through the repository listed below:
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Nola Brantley Memorial Library
721 Watson Boulevard
Warner Robins, Georgia
(478) 923-0128
A public comment period was held from January 23 to March 24, 2000, following the issuance of the PP
on January 23, 2000. The public was notified of the PP and the 45-day public comment period through
mailing of the Robins AFB newsletter (The Rev Up) and through the Warner Robins Sun and Macon
Telegraph newspapers. A public meeting was held on February 10, 2000, to present the PP to a broader
community audience than those that had already been involved at the NPL Site. At this meeting,
representatives from the US EPA and the GA EPD answered questions concerning the remedial
alternatives. This meeting was also used to solicit a wider cross-section of community input on any
issues associated with the NPL Site. Response to the comments received during this period is included in
the Responsiveness Summary (Section 3.0), which is part of this ROD. There have been no significant
changes to the recommended remedy; therefore, no additional public comment period is necessary.
2.4 SCOPE AND ROLE OF OPERABLE UNIT
As with many Superfund sites, the problems at the NPL Site are complex. As a result, work was initially
organized into three OUs:
OU1: The LF04 and the Sludge Lagoon source units;
OU2: The wetlands being addressed under the RCRA regulations delegated to the State of
Georgia (GA EPD); and
OU3: The groundwater contaminated by the LF04 and the Sludge Lagoon source units.
The subjects of this ROD are OU1 and OU3. The overall site cleanup plan is provided below. Please
note that many components of the cleanup plan have already been completed in conformance with the
OU1 and OU3 IRODS (IRP, 1991 and 1995b, respectively).
Operable Unit 1 Past Response:
As specified in the OU1 IROD (IRP, 1991), the past Interim Action remedial responses have been
performed in the presented sequence:
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
In situ volatilization of the Sludge Lagoon waste mass;
Excavation of the Sludge Lagoon waste mass and solidification;
Renovation of the initial LF04 clayey sand cover using geosynthetic fabric and a clay liner (See
Figure 3);
Installation of gas collection system at LF04;
Construction of a new cover over LF04 and the Sludge Lagoon (See Figure 3);
Construction of a run-on diversion structure around LF04;
Installation of a groundwater extraction system at the Sludge Lagoon concurrent with the
groundwater extraction system installed at LF04 (See Figure 4); and
Installation of a leachate collection system at LF04 (See Figure 4).
Operable Unit 1 Activities Proposed in This ROD:
Institutional controls/LUCs for access to the NPL Site and future land use;
Statutory reviews no less often than every five years after the initiation of the remedial action
presented under this ROD; and
No further action regarding the OU1 Interim Actions as described in the IROD.
Operable Unit 3 Past Response:
As described in the OU3 IROD (IRP, 1995b), the past Interim Action remedial responses have been
performed in the presented sequence
Installation of a the OU3 Interim Action groundwater extraction system at LF04 (See Figure 4);
Installation of a GWTS for treatment of the extracted groundwater from LF04 (See Figure 4);
Discharge of the treated groundwater (effluent) to the Ocmulgee River to a preexisting NPDES
permitted outfall; and
Perform annual groundwater monitoring to verify the reduction in contaminant concentrations.
Operable Unit 3 Activities Proposed in This ROD:
Optimization of the current OU3 Interim Action groundwater extraction system by evaluating the
efficiency and effectiveness of the OU3 groundwater extraction system. When the evaluation of
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
the data for two groundwater sampling events indicate that the continued operation of the system
is less efficient and effective than MNA, documentation will be provided by the Air Force to the
US EPA and GA EPD to justify the technical decision for turning off the groundwater extraction
system and transitioning to MNA. The supporting data may include the analytical results,
isoconcentration maps, contaminant trend analyses, groundwater extraction rate data, contaminant
mass removal data, system operating costs, and revised groundwater and transport modeling, as
applicable. The supporting data will sufficiently document the groundwater treatment system's
efficiency and effectiveness. This evaluation, subject to the US EPA and GA EPD review and
approval, will allow for deactivating the OUS groundwater extraction system and transitioning to
MNA when it is determined that MNA is the most appropriate remedial strategy;
Perform annual monitoring to verify the reduction in contaminant concentrations and to assess the
effectiveness of natural attenuation;
Implementation of institutional controls/LUCs for access to the site (land and groundwater) and
future land use; and
Statutory reviews no less often than every five years after the initiation of the remedial action
presented under this ROD.
The overall cleanup strategy is containment of OU1 and remediation of OUS to MCLs. The strategy for
OUS was to remediate the groundwater through a network of extraction wells and treat the contaminated
groundwater prior to discharging in accordance with a preexisting NPDES permit. Ingestion of
groundwater extracted from OUS may pose a risk to human health because the US EPA's acceptable risk
range of 10~4 to 10~6 is exceeded and concentrations of the COCs were greater than the MCLs for drinking
water (as specified in the Safe Drinking Water Act) (See Tables 1 and 2). Current available data supplied
from the Spring 2003 basewide sampling event (Table 3) indicate that the maximum concentrations of
several of the COCs are now below MCLs (Earth Tech, 2003). To address the remaining contamination
in OU3, optimization of the groundwater extraction system will be performed by increasing or decreasing
the number of wells and flow rate of the groundwater extraction network based upon the evaluation of the
efficiency and effectiveness of the OU3 groundwater extraction system. This evaluation, subject to US
EPA and GA EPD review and approval, will allow for deactivating the OU3 groundwater extraction
system and transitioning to MNA when it is determined that MNA is the most appropriate remedial
strategy.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.5 SITE CHARACTERISTICS
The following subsections present a brief but comprehensive overview of the NPL Site.
2.5.1 Conceptual Site Model
As part of the RI/FS, a site-specific conceptual site model (CSM) was developed to support the BRA as
well as the response action for this NPL Site. The CSM was based on the waste sources, pathways, and
receptors potentially present prior to interim remedial actions that have been implemented at the site. The
CSM is presented graphically in Figure 5. It depicts known and suspected historical sources of
contamination (LF04 and the Sludge Lagoon), the source medium (soil) initially contaminated by the
wastes at LF04 and the Sludge Lagoon, release mechanisms by which contaminants migrated from the
source medium to groundwater, exposure media, exposure routes, and human and ecological receptors
that potentially could have been exposed to contaminants at the NPL Site under baseline conditions (i.e.,
in the absence of any remedial actions). The diagram shows that the source medium (OU1) impacted
groundwater (OUS) via infiltration/leaching.
In the CSM diagram (Figure 5), the potentially complete pathways are indicated by an "x" in the
corresponding box representing an exposed receptor. Either an empty box or a box with an "x3" and an
explanatory footnote associated with it indicates incomplete pathways for each receptor. Under the
current land use scenario evaluated at the time the BRA was performed (i.e. industrial landfill near a
residential area and accessible to trespassers and recreators), it was assumed that human receptors
potentially exposed to contaminants in site media included both on-site and off-site trespassers/recreators
and off-site residents. Under the future land use scenario evaluated at the time the BRA was performed, it
was also assumed that if site-related contaminants were transported off-site, both human receptors (e.g.,
hypothetical residents) and ecological receptors (e.g., wetland biota) might be exposed in the
downgradient wetlands. Potentially complete exposure routes identified included ingestion, dermal
contact, and inhalation (dust and vapors) of soil contaminants (OU1); ingestion, dermal contact, and
inhalation (water vapors) of groundwater contaminants (OUS), assuming potential use of
on-site groundwater as potable water supply; ingestion and dermal contact with surface water and
sediment contaminants; and ingestion of wetland contaminants via the aquatic food chain. These
potentially complete pathways were addressed in more detail in the RI and BRA reports for this site
(CH2M Hill, 1990; CH2M Hill, 1993; COM, 1992; COM, 1995; and COM, 1996), and are summarized
in Section 2.7 of this report.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.5.2 Site Overview
The NPL Site is located adjacent to a bluff that forms the western boundary of the Ocmulgee River flood
plain. The Ocmulgee River flood plain extends about one to two miles eastward to the Ocmulgee River.
The NPL Site consists of two past source area OUs: LF04 and the Sludge Lagoon (OU1) and the
groundwater (OUS) contaminated from OU1. LF04 is a 45-acre landfill operated from 1965 to 1978 for
disposal of general refuse and industrial wastes, and the Sludge Lagoon was a 1.5-acre unlined lagoon
used from 1962 to 1978 for disposal of IWTP sludges. The source of groundwater (OUS) contamination
has been through exposure and leaching of contamination from the LF04 source unit.
2.5.3 Surface and Subsurface Features
The NPL Site consists of LF04 and the Sludge Lagoon. There are no other surface or subsurface features.
2.5.4 Sampling Strategy
The sampling strategy conducted and completed during the RI in 1989 was to collect samples from all
media (soils, groundwater, surface water, and sediments) in the vicinity of the NPL Site. Because this
ROD is focused only on OU1 (LF04 and the Sludge Lagoon) and OUS (groundwater), the sediment and
surface water sampling and results are not presented in this ROD. The sample results from the RI phase
dictated many of the interim actions that were completed such as the solidification of the Sludge Lagoon.
Most of the sampling completed since 1989 for OU1 and OUS has focused on groundwater quality. The
Robins AFB basewide sampling program was conducted semiannually in 1991 and 1993 through 1995
and annually from 1996 through 2003. The most recent basewide sampling program report and annual
operational progress report for LF04 provide current data and both historical and concentration trend data
for OUS (Earth Tech, 2003, 2004a, 2004b, 2004c, and 2004d, respectively). In addition, the annual
progress report (Earth Tech, 2004d) provides an evaluation of the effectiveness of the OUS groundwater
extraction system.
2.5.5 Sources of Contamination
The two IRP sites are LF04 and the Sludge Lagoon. LF04 is a 45-acre landfill operated from 1965 to
1978 for disposal of general refuse and industrial wastes. The Sludge lagoon was a 1.5-acre unlined
lagoon used from 1962 to 1978 for disposal of IWTP sludges (Figure 2).
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.5.6 Type of Contamination and Affected Media
The media of concern at the NPL Site include soils/waste materials of LF04 and the Sludge Lagoon
(OU1) and groundwater (OUS) that has been impacted by OU1. This subsection describes the nature and
extent of contamination present in the OU1 waste mass and OUS groundwater. The RI and FS for the
NPL Site provide greater detail identifying environmental samples of all media collected at the NPL Site
(CH2M Hill, 1990; COM, 1992; CH2M Hill, 1993; Earth Tech/Rust E&I, 1999a). The Semi-Annual and
Annual Progress Reports for the years 1998 through 2003 provide details of the environmental sampling
and performance of the remedial system since operation of the groundwater extraction system was
installed in 1998 (Rust E&I, 1998b; Rust E&I, 1998c; Rust E&I, 1999, Earth Tech/Rust E&I, 1999c;
Earth Tech/Rust E&I, 1999d; Earth Tech/Rust E&I, 2000a; Earth Tech, 2000b; Earth Tech, 2001a; Earth
Tech, 200 Ib; Earth Tech, 2004a; Earth Tech, 2004b; and Earth Tech, 2004c;). The basewide
groundwater sampling reports for Robins AFB provide current data and both historical and concentration
trend data for OU3 (Earth Tech, 2003).
Table 1 includes a listing of the most prevalent chemicals that were detected in the source area (OU1)
during the RI performed in 1991. The most prevalent metals contamination observed included lead,
chromium, cadmium, mercury, and arsenic. Organic contaminants found most often in the landfill
leachate included: benzene, toluene, and chlorinated compounds, methylene chloride, trichloroethene
(TCE), and 1,2-dichloroethene. The contaminants most often found in the leachate were also found in the
Sludge Lagoon leachate. However, for most contaminants, concentrations were higher in samples
collected and analyzed from the Sludge Lagoon area.
Table 2 presents the COCs for OU3 (groundwater) as generally reported in the 1999 FS (Earth Tech/Rust
E&I, 1999a). It should be noted that the FS completed in 1999 was based on a list of COCs derived from
data collected and analyzed during the 1998 basewide sampling event, while the BRA completed in 1993
was based on data collected in 1989. In addition, a recent analysis of data collected during the annual
basewide groundwater sampling programs from the period of 1999 through 2003 has indicated that two
inorganic contaminants (nickel in the surficial aquifer and chromium in the Quaternary alluvial aquifer)
should no longer be considered as COCs (Appendix A). The list of COCs developed in the 1999 FS
differs from those developed in the 1989 BRA. Section 2.7 of this ROD includes analytical data from
both 1989 and 1999. A CSM on which the risk assessment and response action are based is presented as
Figure 5.
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Robins Air Force Base
Warner Robins, Georgia
The quantity and volume of waste has not been calculated in previous reports but has been estimated for
this ROD. The volume of waste mass identified as OU1 is approximately 900,000 tons of soils and
saturated soils, while the volume of contaminated groundwater associated with OUS is approximately 76
million gallons.
Figure 6 provides a generalized depiction of the hydrogeologic conditions at the NPL Site. Historical
plume maps for TCE and lead from 1989 and other annual sampling events are presented in Figures 7
through 22. Based upon the results of the COC identification for the 1999 FS report, no remedial
alternatives will be developed for both the lower Providence unit within the Providence aquifer and the
Blufftown aquifer since they do not contain COCs. The lower Providence unit within the Providence
aquifer and the Blufftown aquifer are, however, addressed in relation to potential future impacts by the
COCs. Since 1998, when the OUS groundwater extraction system was installed and operated, the COCs
have been steadily declining (Figures 7 through 17). The 2003 data from recovery wells RW4 and RW5
groundwater samples indicate that TCE concentrations are rapidly approaching cleanup levels. In
addition, it appears that the concentrations of lead are also exhibiting decreasing trends (Figures 18
through 22), likely attributable to natural attenuation mechanisms (i.e. dispersion, dilution, and
adsorption).
2.5.7 Location of Contamination and Potential Routes of Migration
Contaminants associated with groundwater in the surficial aquifer, the Quaternary alluvial aquifer, and
the upper Providence unit may migrate and discharge to the wetlands neighboring LF04. However,
migration of any of the contaminants through Layer 1 (surficial aquifer and peat/clay unit) will be at a
very slow rate due to natural attenuation mechanisms (Figure 6). Theoretically, velocities of
contaminants may increase in the Quaternary alluvial aquifer and upper Providence unit.
The conditions at the NPL Site, particularly in portions of Layer 1, appear to be favorable for the natural
breakdown of the organic contaminants by the action of the in situ bacterial population in the subsurface
(Earth Tech, 2003). Evidence of the degradation of contaminants (natural attenuation) in both the soil and
groundwater includes:
Depressed dissolved oxygen levels,
Elevated chloride and sulfate levels downgradient,
Increased methane production, and
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Presence of breakdown products.
The pathways by which human and ecological populations potentially could be exposed to site-related
contamination are illustrated in the CSM (Figure 5). As a result of the actions that have been completed
as part of the OU1 IROD (i.e., capping of the landfill), exposure pathways for human and ecological
receptors are incomplete for OU1. Human populations could be exposed to OUS groundwater through
contact with groundwater under a future residential use scenario; however, since there are no potable
water wells within or downgradient of the NPL Site, there are no complete exposure pathways to human
receptors under current conditions. Previous evaluation of the downgradient wetlands (Earth Tech/Rust
E&I, 2000) found that human and ecological receptors were not at risk from potential discharge of
contaminants inOUS groundwater.
2.5.8 Hydrogeology
The groundwater formations underlying the NPL Site are complex. Figure 6 depicts the four aquifers
beneath the NPL Site. These four aquifers consist of (from top to bottom) the surficial aquifer, the
Quaternary alluvial aquifer, the Providence aquifer (divided into the upper Providence and the lower
Providence units), and the Blufftown aquifer. The general groundwater flow direction within the geologic
formations beneath the NPL Site is from west to east, generally towards the Ocmulgee River. The entire
flood plain of the Ocmulgee River is a discharge area for groundwater. Where the Ocmulgee River has
eroded part of the geologic sediments, there is a significant upward gradient from the deeper units toward
the shallow Quaternary units and surface waters. Flow in the near-surface Quaternary units is generally
toward the river or to smaller streams in the flood plain. The drainage ditch that forms the northern
boundary of the NPL Site also acts to control local groundwater flow because shallow groundwater in the
area discharges upward into the ditch from both the north and south.
Due to the complexity of the site hydrology, five "layers" that represent the aquifers or combinations of
aquifers and site conditions were defined. The layers were utilized for groundwater and contaminant
computer modeling purposes and to illustrate contaminant plumes. These layers are identified in Figure 6
and described below:
Layer 1 consists of the surficial aquifer and the peat/clay unit;
Layer 2 consists of the Quaternary alluvial aquifer and part of the Providence aquifer (upper
Providence unit);
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Layer 3 consists of the Providence aquifer (upper Providence unit);
Layer 4 consists of the Providence aquifer (lower Providence unit); and
Layer 5 consists of the Blufftown aquifer.
2.6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USES
This section describes the current and reasonably anticipated future land uses and current and potential
beneficial groundwater uses at the NPL Site. Currently, land use at the NPL Site is non-residential.
Future land use is to remain non-residential. For purposes of this ROD, non-residential use excludes uses
typically associated with permanent, human habitation, and working environments but may include uses
related to intermittent human contact that pose no threat to human health or the environment. Land use in
the vicinity of the NPL Site varies from wetlands downgradient to the south and east; industrial uses
upgradient to the west and north; and residential (Base housing) upgradient to the southwest. Future land
use for this area of the Base is not expected to vary from the current land use. Documentation of both
current and future land uses for the Base, including the NPL Site, is presented in the Base Comprehensive
Plan. In addition, information regarding LUCs is also included in the Feasibility Study (Earth Tech/Rust
E&I, 1999a) and the PP (Earth Tech/Rust E&I, 1999b) as a part of the Administrative Record.
Groundwater beneath the NPL Site is not currently used for drinking water or irrigation wells. However,
the GA EPD considers all groundwater within the State of Georgia to be a potential source of drinking
water. This policy would be equivalent to categorizing groundwater within the State of Georgia as Class I
or II utilizing the Federal groundwater classification guidelines. This classification is made since the
groundwater aquifers are either potential drinking water or may discharge to an ecologically important
resource. It is not anticipated that groundwater will be utilized as a drinking water resource from the
upper Providence unit, the Quaternary alluvial aquifer, or the surficial aquifer. The lower Providence
unit, which provides non-potable water at other Base locations hydraulically removed and/or upgradient
from the NPL Site, is not currently used as a drinking water resource on the Base. It is not anticipated
that the future needs of the Base will require the use of this groundwater from the lower Providence unit
for drinking water even though it is currently considered of quality to be used as a drinking water source.
2.7 SUMMARY OF SITE RISKS
As part of the RI process, BRAs were previously prepared for OU1 and OUS in order to evaluate the
potential risks to human health and the environment from chemicals identified during investigations at the
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Robins Air Force Base
Warner Robins, Georgia
NPL Site. The purpose of the BRAs was to estimate baseline risk, that is, the risk the site might pose if
no remedial action were taken. These assessments were used to identify the COCs and potentially
complete exposure pathways, and to develop remedial goal options for COCs identified in site media.
The BRAs provided the basis for determining whether or not remedial action was necessary and the
justification for performing remedial action at the NPL Site. The risk assessments were presented in the
RI and BRA reports (CH2M Hill, 1990; CH2M Hill, 1993; COM, 1992; COM, 1995; and COM, 1996).
A summary of the site-related risks identified in those earlier BRAs is provided in this section of the
ROD. Chemical specific toxicological data used in the BRAs are presented in Tables 5 through 8; and the
exposure assumptions used for human receptors in groundwater are presented in the footnotes of Table 9.
Based on the RI findings, contaminants from LF04 and the Sludge Lagoon historically impacted site soils
and were released to the groundwater (OUS). Potential risks from site-related contaminants in these
media were evaluated in the BRAs based on then current and assumed future conditions. Upon
completion of the BRAs, an FS was conducted for OU1 and OUS (Earth Tech/Rust E&I, 1999a). The
following subsections provide summaries of: (1) risks from OU1, (2) risks from OUS based on previous
human health and ecological risk assessments, and (3) current risks from OUS.
2.7.1 Summary of Risk from OU1
In the 1990 BRA (CH2MHill, 1990), four human health COCs (arsenic, cadmium, chromium and
chloroform) were identified in site surface soil (OU1) as posing unacceptable risks to on-site child
trespassers and off-site residents under the current land use scenarios evaluated at that time. Subsequently
at OU1, interim remedial actions were performed at the LF04 and the Sludge Lagoon source units. As
described in Sections 1.4.1 and 2.4, interim remedial actions involving the contaminated soils and waste
materials associated with LF04 and the Sludge Lagoon have included treatment, removal, and capping.
The interim remedial actions that were performed at OU1 subsequent to the BRAs eliminated the
previously complete exposure pathways at OU1 that were evaluated in the BRAs and through which the
soil COCs potentially posed risk. The human exposure pathways associated with the downgradient
wetlands were evaluated in a BRA for the OU2 wetlands (Earth Tech/Rust E&I, 2000). That BRA did
not find that OU1 posed current or future risks to human receptors in the wetlands. Consequently, the
wetland exposure pathways, based on storm water runoff from OU1, were shown to be insignificant.
The BRAs for OU1 determined that there were no significant pathways for exposure of ecological
receptors to contaminants in site soils under the current and future conditions evaluated. Therefore,
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on-site exposure pathways associated with ecological risks were considered to be incomplete, and no
ecological COCs were identified for OU1. The ecological risk assessments for OU1 were documented in
Section 5.0, Environmental Risk Characterization, in Appendix M of the RI/BRA Report (CH2M Hill,
1990) and Section 6.3, Ecological Risk Assessment, in Volume I of VI in the RI/BRA Report (CH2M
Hill, 1993). In addition, the ecological exposure pathways for the downgradient wetlands were evaluated
in the BRA for the OU2 wetlands (Earth Tech/Rust E&I, 2000), which found that OU1 did not pose
current or future risks to ecological receptors in the wetlands. Consequently, wetland exposure pathways
for human receptors based on stormwater runoff from OU1 were shown to be insignificant, and no
ecological COCs associated with OU1 were identified.
All potential exposure pathways previously identified for OU1 are presently considered incomplete and/or
insignificant due to the completion of the Interim Actions. Exposure routes for the exposure media (i.e.,
air, the food chain, and surface water and sediment via stormwater runoff) have been eliminated by the
capping of LF04 and the Sludge Lagoon, as well as other remedial actions. Thus, the remedial objectives
for protection of human health and the environment have now been met for OU1. Accordingly, the
Interim Actions conducted at OU1 are the final actions and no further remedial actions, except for LUCs,
are necessary for this unit.
2.7.2 Summary of Risk from OU3
Because concentrations of some human health COCs in OU3 groundwater still exceed MCLs, additional
remediation activities are required for OU3 to meet RAOs. Accordingly, this section provides a more
detailed summary of the BRAs that provided the basis of the ongoing remedial actions for OU3. The
following subsections provide summaries of the previous human health risk assessments for OU3, the
previous ecological risk assessments for OU3, and current risks from OU3.
2.7.2.1 Summary of Previous Human Health Risk Assessments for OU3
The methods and results of the BRAs previously performed to evaluate risk from OU3 are described
below based on four main components of a BRA:
2.7.2.1.1 Identification of Chemicals of Concern
The ultimate result of the exposure assessment, effects assessment, and risk characterization
described below was the identification of COCs in OU3 groundwater based on cancer risk and/or
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noncancer hazard. The human health COCs identified in the previous BRAs for OUS indicated
the need for remedial action regarding OUS. These COCs, which were identified in groundwater
based on potential exposures of hypothetical future on-site residents, are listed in Table 4 and are
summarized below by aquifer:
Quaternary alluvial aquifer: thirteen volatile organic compounds (VOCs), ten metals, three
polynuclear aromatic hydrocarbons (PAHs), and dieldrin;
Upper Providence unit: nine VOCs, five metals (arsenic, beryllium, cadmium, vanadium, and
zinc), 2,4-dinitrophenol, and dieldrin;
Lower Providence unit: three VOCs (bromomethane, trans-1,3-dichloropropene, and TCE),
four metals (arsenic, beryllium, cadmium, and zinc), 2,4-dinitrophenol, and dieldrin;
Blufftown and Cusseta aquifer: four metals (arsenic, beryllium, cadmium, and zinc).
In BRAs, the exposure point concentration (EPC) for a chemical typically is based on the 95 percent
upper confidence limit of the arithmetic mean concentration (US EPA, 2000a). However, for sites with
limited amounts of data or extreme variability in the data, the maximum detected concentration is
commonly used as a default EPC. For each COC in groundwater (OUS), the EPC and the basis for
deriving this value are also presented in Table 4. As indicated on the table, the maximum detected
concentration was conservatively used as the "upper bound" EPC in the risk assessments for the site
(i.e., the concentration that was used to estimate the highest exposure and associated risk from each
COC). It should also be noted that the BRAs also calculated exposures based on mean concentrations in
order to provide a plausible range of risks in support of risk management decisions for the NPL Site.
2.7.2.1.2 Exposure Assessment
The exposure assessment components of the BRAs for OUS were documented in Section 4.2, Exposure
Pathway Assessment, in Appendix M of the RI/BRA Report (CH2M Hill, 1990) and Section 6.2.3,
Exposure Assessment, in Volume 1 of 6 in the RI/BRA Report (CH2M Hill, 1993). In the BRAs,
potential human exposure pathways were identified based on consideration of current and potential future
land uses of the site and surrounding areas. A complete pathway includes a chemical source and release
mechanism, a transport or retention medium, an exposure point where human contact with the
contaminated medium occurs, and a route of intake for the contaminant into the body at the exposure
point. If any one of these elements is missing, the pathway is incomplete and is not considered further in
the risk assessments.
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As presented in the site-specific CSM diagram (Figure 5), potentially complete exposure pathways were
evaluated in the BRAs based on current land use scenarios at the time the BRAs were performed. When
the BRAs were performed there were no on-site water supply wells, which continues to be in agreement
with the current conditions; consequently, potential human exposure pathways to groundwater were
considered to be incomplete. Hypothetical future land use scenarios were evaluated based on the
assumption of potential future use of on-site groundwater as a potable water supply for on-site residents,
in accordance with US EPA Region IV guidance (US EPA, 1989a). Future residents were assumed to be
exposed to COCs in groundwater via ingestion of tap water and inhalation of water vapors. Groundwater
exposures were conservatively evaluated, given that there are presently no potable groundwater wells at
the site, and on-site groundwater is not likely to be used as a water supply source in the future.
Receptors and pathways evaluated in the BRAs also included off-site child trespassers/recreators exposed
to surface water, sediment, and fish from the downgradient wetlands. However, the US EPA, the
GA EPD, and Robins AFB agreed in 2003 that the contamination found in the adjacent wetlands did not
originate from OU1 (US EPA, 2003b). Accordingly, these surface water, sediment, and fish pathways are
not included herein.
Chemical-specific intakes (estimated doses) were calculated for the potential receptors and their exposure
pathways as part of the quantitative evaluation in the BRAs. These estimates were based on the chemical -
and medium-specific EPCs for the COCs and default and/or site-specific exposure assumptions. These
exposure assumptions were developed using US EPA risk assessment guidance such as the Risk
Assessment Guidance for Superfund (US EPA, 1989a) and the Exposure Factors Handbook (US EPA,
1989b and 1990a). The exposure factors used to estimate intake and dose (including exposure frequency,
exposure duration, exposure time, body weight, and intake rates) for the future residential scenarios in the
BRAs are presented within the footnotes of the risk calculation summary table (Table 9).
2.7.2.1.3 Toxicity Assessment
The toxicity assessment components of the BRAs for OUS were documented in Section 3.0, Toxicity
Assessment, in Appendix M of the RI/BRA Report (CH2M Hill, 1990) and Section 6.2.2, Toxicity
Assessment, in Volume 1 of the RI/BRA Report (CH2M Hill, 1993). The toxicity assessments used data
available at the time the BRAs were performed regarding the potential of each COC to cause adverse
health effects in exposed individuals. Two categories of toxicity were evaluated: cancer risk from
carcinogens and noncancer hazard from noncarcinogens. The chemical-specific toxicological data used
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in the BRAs are presented in Tables 5 through 8. The cancer toxicity data available for the COCs is
presented in Table 5 (for oral/dermal exposures) and Tables 6a and 6b (for inhalation exposures). The
noncancer toxicity data available for the COCs is presented in Tables 7a and 7b (for oral/dermal
exposures) and Table 8 (for inhalation exposures).
In evaluating carcinogenic effects, the slope factor (SF) was used in the BRAs to estimate an upper-bound
lifetime probability of an individual developing cancer as a result of exposure to a particular level of a
potential carcinogen. The chemical-specific SFs used for carcinogenic COCs in the BRAs, and their
weight-of-evidence classification based on the strength of the evidence that the chemical is a human
carcinogen, are presented in Tables 5, 6a, and 6b based on the oral, dermal, and inhalation routes of
exposure, respectively. It should be noted that inhalation SFs for the eight volatile COCs were not
documented in the 1993 BRA, as shown in Table 6a. However, in order to provide thorough
documentation of currently available toxicological information for the COCs, supplemental inhalation
SFs have been provided in this ROD for those COCs that lacked such data in the 1993 BRA (Table 6b).
Evaluation of noncarcinogenic effects in the BRAs was based on the reference dose (RfD), defined as an
estimate of a daily exposure level to a specific chemical that is not expected to cause any deleterious
noncancer effect. The chemical-specific RfDs based on the oral and dermal routes of exposure are
presented in Tables 7a and 7b. Dermal RfDs are not presented since there were no noncarcinogenic
COCs identified for the dermal exposure pathway. Information regarding the type of effect (e.g. chronic
or subchronic), target organ, and factors used in deriving the oral RfDs were not presented in the BRAs,
and inhalation RfDs were not presented in the 1993 BRA. However, in order to provide thorough
documentation of currently available toxicological information for the COCs, available noncancer toxicity
data were added as supplemental information in this ROD in Tables 7b and 8.
The sources of toxicity data in the previous BRAs are shown in Tables 5, 6a, 7a, and 8. For the COCs in
soil (CH2M Hill, 1990), the toxicity values used were primarily obtained from the US EPA Integrated
Risk Information System (IRIS) (US EPA, 1988). If values were not available from IRIS, the Health
Effects Assessment Summary Tables (HEAST) (US EPA, 1989c) or the Superfund Public Health
Evaluation Manual (SPHEM) (US EPA, 1986) were consulted in this assessment. For the COCs in
groundwater identified in the BRA (CH2M Hill, 1993), the toxicity values used in the assessment were
also primarily obtained from IRIS (US EPA, 1992a). If values were not available from IRIS, HEAST
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(US EPA, 1992b) or the Environmental Criteria and Assessment Office (no reference provided in report)
were consulted.
In the supplemental tables of toxicity values provided in this ROD (Tables 6b, 7b, and 8), values were
also obtained primarily from IRIS. If toxicity values were not available from IRIS, HEAST, or the
Superfund Health Risk Technical Support Center-National Center for Environmental Assessment
(SHRTSC-NCEA) of the US EPA were consulted. IRIS and HEAST toxicity values were obtained from
the Electronic Handbook of Risk Assessment Values (EHRAV, 2000). The SHRTSC-NCEA values were
obtained from the US EPA Risk-Based Concentration Table (US EPA, 2000b).
2.7.2.1.4 Risk Characterization
The risk characterization components of the BRAs for OUS were documented in Section 4.3, Public
Health Risk Characterization, in Appendix M of the RI/BRA Report (CH2M Hill, 1990), and Section
6.2.4, Risk Characterization, in Volume 1 of 6 in the RI/BRA Report (CH2M Hill, 1993). This section
summarizes the BRA results, uncertainties and assumptions associated with the BRAs, and conclusions of
the BRAs with regard to OU3.
Summary of BRA Results
For carcinogens, risks are expressed as the incremental probability of an individual developing cancer
over a lifetime (e.g. 70 years) as a result of exposure to the carcinogen. The cancer risk estimate
(expressed as a unitless probability) is the lifetime average daily dose [chronic daily intake (CDI)J
multiplied by the SF. Risks are standardly expressed in scientific notation (e.g., 1E-06 or 1 x 10"6). An
excess lifetime cancer risk of 1 x 10"6 indicates that an individual experiencing the reasonable maximum
exposure estimate has a 1 in 1,000,000 chance of developing cancer as a result of site-related exposure.
This is referred to as "an excess lifetime cancer risk" for the individual because this risk would be in
addition to the cancer risks that may result from other causes that are not site-related. US EPA's
generally acceptable cancer risk range for site-related exposures is 10"4 to 10"6. Risks greater than one
excess cancer in one million people (10~6) are considered potentially significant by the GA EPD. The GA
EPD benchmark was used for determining COCs. Therefore, those chemicals identified during the risk
characterization as contributing significantly (chemical-specific risk that equals or exceeds 1E-06) to a
medium with a total cancer risk of 1E-06 or greater were classified as human health COCs.
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For noncarcinogens, effects were evaluated by dividing an estimated exposure level (GDI or dose) by the
RfD to calculate a hazard quotient (HQ) for the chemical in that medium. The GDI and the RfD are
expressed in the same units and represent the same exposure period (i.e., chronic, sub-chronic, or short-
term). An HQ less than 1.0 generally indicates that toxic noncarcinogenic effects from that chemical are
unlikely because the receptor's dose of the chemical is less than the RfD. A hazard indices (HI) is
calculated by adding the individual HQs for all chemicals that affect the same target organ (e.g., liver) or
that act through the same mechanism of action within a medium or across all media to which a given
individual may be reasonably exposed. An HI greater than 1.0 indicates that site-related exposures to
contaminants may present a hazard to human health [i.e., a chemical may be identified as a COC if it
contributes significantly (HQ of 0.1 or greater) to a critical effect HI of 1.0 or greater for a particular
pathway].
Risks from carcinogenic COCs and hazards from noncarcinogenic COCs from potential exposures of
future on-site residents to groundwater are presented in Table 9. The risk and hazard estimates presented
in these tables are consistent with the information presented in the BRAs. As documented in the 1993
BRA, specific risk and hazard estimates are presented for each groundwater monitoring well within each
aquifer under the future residential scenario and include total risks and hazards associated with each well
based on all chemicals of potential concern (i.e., not limited to COCs only). Cumulative total risks and
hazards for all wells are not presented in these tables, as this information was not documented in the BRA
(only well-specific risks were presented in the BRA to provide a spatial representation of area risks). It
should also be noted that since the primary target organs for associated noncarcinogenic COCs were not
presented in the BRAs, such information is not included in the hazard calculations in Table 9. (However,
as previously discussed, target organs for the COCs are presented on Tables 7b and 8.)
For carcinogens, as noted above, total cumulative risks were not calculated for groundwater exposures.
For the future residential scenario, the maximum total cancer risks from on-site wells from each aquifer
were calculated in the 1993 BRA to be 3.0E-01 (at LF4-4) in the Quaternary alluvial aquifer, 5.0E-05
(at LF4-38) in the upper Providence unit, 4.0E-05 (at LF4-43) in the lower Providence unit, and 3.0E-04
(at LF4-BL1) in the Blufftown and Cusseta aquifer (Table 9). With the exception of groundwater from
the Quaternary alluvial aquifer and Blufftown and Cusseta aquifer, all of these total cancer risks exceeded
the GA EPD benchmark of 1E-06 but were within the US EPA target risk range of 1E-06 to 1E-04. Total
cancer risks from groundwater in the Quaternary alluvial aquifer and the Blufftown and Cusseta aquifer
exceeded the US EPA target risk range as well as the GA EPD benchmark.
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For noncarcinogens, as noted above, total cumulative His were not calculated for groundwater exposures.
For the future residential scenario, the maximum His from on-site wells from each aquifer were 429.3
(at LF4-6) in the Quaternary alluvial aquifer, 1.4 (at LF4-42) in the upper Providence unit, 2.5
(at LF4-PR1) in the lower Providence unit, and 11.8 (at LF4-BL3) in the Blufftown and Cusseta aquifer
(Table 9). All of these His exceed the US EPA and the GA EPD benchmark of 1.0, with the majority of
these exceedances based on COCs in groundwater from the Quaternary alluvial aquifer and the Blufftown
and Cusseta aquifer.
Overall, the results of the quantitative risk characterization in the BRAs indicated that there were
unacceptable cancer risks and noncancer hazards to potential human receptors associated with site-related
COCs (i.e., VOCs and metals) in OUS groundwater under a hypothetical future residential land use
scenario. A total of 28 human health COCs (including 13 volatile organic compounds (VOCs), three
PAHs, 11 metals, and dieldrin) were identified by the BRAs in groundwater from the Quaternary alluvial
aquifer, the upper and lower Providence units, and the Blufftown and Cusseta aquifer.
All total cancer risks, except for groundwater from the Quaternary alluvial aquifer, exceeded the GA EPD
benchmark but were within the US EPA acceptable risk range. Total cancer risks also significantly
exceeded the US EPA target risk range for COCs in groundwater from the Quaternary alluvial aquifer.
Total noncarcinogenic hazard assessed using His exceeded the US EPA and the GA EPD benchmark of
1.0, with significant contributions from COCs in both the Quaternary alluvial aquifer and Blufftown and
Cusseta aquifer. Consequently, based upon these BRA findings, remedial actions were recommended for
OUS to address potential human health risks from the groundwater COCs.
BRA Uncertainties and Assumptions
Uncertainties and assumptions are inherent in the process of risk assessment. This section provides a
discussion of the uncertainties associated with key site-related variables and major assumptions used in
the BRAs in order to address their potential effect on the risk and hazard estimates.
Sampling and Analysis: The RI sampling data collected at any on-site location were inevitably a limited
subset of the nearly unlimited quantity of data that potentially could have been collected, and as such,
may not have been completely representative of site contaminant levels. Overall, the quality
assurance/quality control program implemented in the RI served to reduce sources of variability, although
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some degree of variability or standard error in the analyses, representativeness of samples, sampling
variability, and heterogeneity of the sample matrix was inevitable.
Environmental Fate and Transport: The quantitative assessment in the BRAs assumed that no
contaminant loss or transformation of site contaminants had occurred. Concentrations of COCs used in
the BRAs were based on chemical concentrations from the RI sampling that were not reduced to account
for degradation, dilution, or dispersion. This assumption was very conservative and likely resulted in
overestimation of risks and hazards associated with the site, especially for VOCs.
Exposure Estimation: The evaluations of potential exposure pathways and receptors were based on
potential current and hypothetical future land uses identified at the time the BRAs were performed.
Site-specific receptors were identified to the extent possible and exposure parameters were tailored to
these receptors to minimize uncertainty in the postulated exposure scenarios and the exposure assessment.
Although an unlikely scenario, given that the reasonably anticipated future land use at the units will
remain industrial, the hypothetical future residential scenario was evaluated in the BRAs in accordance
with US EPA Region IV guidance (US EPA, 1989a). Potential use of on-site groundwater from each of
the four aquifers was also quantitatively assessed in the BRAs, although there are no existing on-site
water supply wells and site groundwater is not expected to be used as a potable water supply source under
future conditions.
Values assumed for exposure parameters (e.g., exposure frequency, exposure duration, exposure time,
body weight, and intake rates) used in calculations of receptor intakes were based primarily on
recommended default values from US EPA risk assessment guidance. These assumptions may have
resulted in either the underestimation or overestimation of intakes, depending on the accuracy of the
assumptions relative to actual site conditions and land uses. Dermal exposures were not quantified, which
may have contributed to uncertainty regarding total risk estimates. Maximum detected concentrations of
chemicals were used to represent highest potential exposures (e.g., upper bound), which is likely to have
overestimated risks and hazards.
Toxicological Data: Uncertainties associated with toxicological data included extrapolation from high to
low doses and from animals to humans; species differences in uptake, metabolism, and organ distribution;
species differences in target site susceptibility; and human population variability with respect to diet,
environment, activity patterns, and cultural factors. The assumption that all of the chemical effects were
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additive may have resulted in either the underestimation or overestimation of risks because concurrent
exposure to several contaminants may either have synergistic or antagonistic effects. In the BRAs, the
absence of toxicity values for some of the COCs may have contributed to the underestimation of risks and
hazards.
BRA Conclusions for OU3
In the 1993 BRA, human health COCs identified in OUS groundwater included several VOCs, PAHs,
metals, and dieldrin in the Quaternary alluvial aquifer and the upper Providence and lower Providence
units and metals in the Blufftown and Cusseta aquifer under a future residential land use scenario
(i.e., assuming potential future use of on-site groundwater as a potable water supply). The GA EPD
requires all groundwater to be considered a potential drinking water source regardless of the reasonably
anticipated future land use. Accordingly, it was concluded based on the BRA results, that the OUS
groundwater required remediation to protect public health or welfare or the environment from actual or
threatened releases of hazardous substances from this site. Interim remedial actions were subsequently
performed to address the risks and COCs identified in the BRA based on future use of groundwater.
Under current land use scenarios, there were no potentially complete pathways to site groundwater.
2.7.2.2 Summary of Previous Ecological Risk Assessments for OU3
In the BRAs for OUS, it was determined that there is no exposure of ecological receptors to site
groundwater under current and reasonably anticipated future conditions. Therefore, on-site exposure
pathways associated with ecological risks were considered to be incomplete and no ecological COCs were
identified. The ecological risk assessments for OUS were documented in Section 5.0, Environmental
Risk Characterization, in Appendix M of the RI/BRA Report (CH2M Hill, 1990) and Section 6.3,
Ecological Risk Assessment, in Volume 1 of 6 in the RI/BRA Report (CH2M Hill, 1993). As discussed
above for OU1, the ecological exposure pathways based on groundwater discharge to the downgradient
wetlands were evaluated in the OU2 Wetlands BRA (Earth Tech/Rust E&I, 2000), which found that OUS
did not pose current or future risks to ecological receptors in the wetlands. Consequently, wetland
exposure pathways for ecological receptors based on discharge of OUS groundwater were shown to be
insignificant, and no ecological COCs were identified for OUS. Overall, based on the findings of the
BRAs, no ecological COCs were identified for OUS (groundwater) under either the then current or
potential future ecological exposure scenarios.
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2.7.2.3 Summary of Current Risk from OU3
Interim remedial activities were conducted at the NPL Site following the completion of the 1993 BRA
and prior to the development of the FS for OUS and OU1 (Earth Tech/Rust E&I, 1999a). In order to
consider the effects of these interim actions, additional groundwater screening was performed during the
FS to identify the final COCs in groundwater that needed to be addressed under the remedial action for
OUS. The FS also developed remedial goals to address the potential risks associated with the COCs in
OUS groundwater.
The final COCs identified by the FS were those constituents with maximum detected concentrations in
OUS groundwater that exceeded their respective MCLs. The concentrations used in the screening were
based on laboratory analytical data from the Spring 1998 basewide groundwater sampling event, which
were the most recent analytical data available for use in the reevaluation of COCs in the 1999 FS
(Rust E&I, 1998a). The MCLs used in the evaluation were risk-based values protective of human health
and the environment, as defined in the Federal Drinking Water Regulations and Health Advisories
(US EPA, 1996). Chemicals with maximum detected concentrations in groundwater that were less than
their respective MCLs were not identified as final COCs in groundwater and were eliminated from further
evaluation in the FS. Each chemical that exceeded its respective MCL was further evaluated in the FS
based on additional considerations, including its frequency of detection, detected concentration relative to
its MCL (i.e., statistical difference), and frequency of detection above its MCL. Based on this evaluation,
the constituents identified as COCs in groundwater included several VOCs and metals in the surficial and
Quaternary alluvial aquifers and the upper Providence unit (Table 2).
A more recent analysis of data collected by the annual basewide groundwater sampling program during
the period 1999 through 2003 indicated that two of the inorganics previously identified as COCs (nickel
in the surficial aquifer and chromium in the Quaternary alluvial aquifer) should no longer be considered
COCs (Appendix A). Therefore, the "final" COCs identified for the OUS groundwater were those shown
in Table 10, which provides detected concentrations (e.g., minimum, maximum, and mean), frequencies
of detection, and exposure point concentrations for the COCs from the Spring 1998 basewide sampling.
Based on the 1993 BRA and the results of the final COC identification in the FS, it was concluded that
the lower Providence unit and Blufftown aquifer either did not contain site-related constituents or the
constituents present were eliminated as a concern based on other lines of evidence. As discussed in the
FS, chemicals detected in these groundwater layers included bis(2-ethylhexyl)phthalate (BEHP) in
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groundwater from the lower Providence unit and Blufftown aquifer, and nickel and chromium in
groundwater from the lower Providence unit. The estimated detected concentrations of BEHP in
groundwater samples were concluded to be laboratory artifacts (i.e., the blank was contaminated);
therefore, BEHP was not considered to be site-related. Detected concentrations of chromium and nickel
(as well as BEHP in groundwater from the upper Providence unit) only exceeded their respective MCLs
in one sample and were eliminated based on the infrequency of their MCL exceedances. As a result, no
final COCs were identified in the lower Providence unit or Blufftown aquifer.
More recent data for the OUS groundwater COCs are shown in Table 3. This table provides the
maximum detected concentration of each COC in each aquifer/unit, the well at which that concentration
was detected, and the current MCL for each COC (US EPA, 2003a). It also shows for comparison the
maximum detected concentrations from the Spring 1998 basewide sampling data that were previously
evaluated in the FS. Comparison of the 2003 data to the 1998 data indicates that the maximum detected
concentrations of many COCs have decreased, particularly in the surficial aquifer.
2.8 REMEDIAL ACTION OBJECTIVES
The RAOs address unit-specific contaminants (e.g. final COCs), media of concern, potential exposure
pathways, and remediation goals. The RAOs are based on the nature and extent of contamination,
threatened resources, and the potential for human and environmental exposure. Initially, preliminary
remediation goals are developed based upon ARARs or other information from the RIs and BRAs. The
RAOs for OU1 (containment) will be met through the implementation of the Interim Action remedies and
institutional controls/LUCs. All potential exposure pathways for OU1 are presently considered
incomplete and/or insignificant due to the completion of the Interim Actions.
The RAOs will be met for OU3 by implementing the remedy described in this ROD. Based on the
evaluation of the BRA, chemical-specific ARARs (i.e., MCLs), and the potential exposure route and
receptors, the RAOs for OU3 groundwater in the surficial aquifer, the Quaternary alluvial aquifer, and the
upper Providence unit are to:
Prevent the use of groundwater having potential carcinogens and noncarcinogens in excess of
established Federal and State ARARs (MCLs) through containment and institutional
controls/LUCs,
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Restore the surficial aquifer, Quaternary alluvial aquifer, and the upper Providence unit to
established MCLs (Table 2), if technically feasible, and
Prevent potential impact to the neighboring wetlands.
The risks associated with containment for OU1 are greater than those associated with complete removal
actions; therefore, institutional controls/LUCs are necessary for protection of human and ecological
receptors. Containment for OU1 and OUS includes institutional controls/LUCs as outlined under Section
2.12 (Selected Remedy) of this ROD. Because the anticipated future land use for this site is non-
residential, containment for both OU1 and OUS was selected as a RAO. Because all groundwater is
classified as potential drinking water, RAOs for OUS include treatment of groundwater to drinking water
standards.
2.9 DESCRIPTION OF ALTERNATIVES
As part of the investigation/assessment process for the NPL Site, OUs 1 and 3, a FS was performed using
groundwater data from the 1998 basewide sampling event (Rust E&I, 1998a). Detailed information
regarding the development and evaluation of remedial alternatives can be found in the FS report
(Earth Tech/Rust E&I, 1999a). Through issuance and acceptance of the ISA, the remedy for OU1
(containment through capping in place) and institutional controls/LUCs has already been chosen as the
final remedy; therefore, no alternatives for OU1 are presented.
The NCP directs that a range of alternatives, including treatment and containment combinations, be
evaluated. Consideration of a "no action" alternative is required by the NCP. However, it should be
noted that in the FS and per the agency-approved ISA (Robins AFB, 1998), the "no action" alternative
included certain aspects of the Interim Action presently being conducted at OUS. In order to provide
alternatives that provide no engineered remedies, a "baseline conditions" alternative and a MNA remedy
were developed.
Remedial alternatives were derived from technologies retained following a screening evaluation presented
in the FS report (Earth Tech/Rust E&I, 1999a). Based on computer modeling presented in the FS, the
estimated time to reach remediation goals for all alternatives was greater than 30 years. For preparing
cost estimates for each alternative, the NCP limits the time period to 30 years. Therefore, each of the cost
estimates presented in the FS were compiled for a time period also equal to 30 years. However, it should
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be noted that based on data from 1999 to present (2003), remediation time is likely to be much shorter
than 30 years, as indicated in Figures 8, 11, 12, 14, 15, 17, 19, and 22.
Remediation goals are based on ARARs. ARARs are cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under Federal, State, or local environmental
law that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or
other circumstance at a CERCLA site. For OU3 (groundwater), only MCLs have been identified as
chemical-specific ARARs. Although the groundwater is not a current source of drinking water, all
groundwater in Georgia is classified as a potential source of drinking water. As such, MCLs are the
current RAOs for groundwater contaminants. The chemical-specific MCLs for the final COCs (Table 10)
in groundwater are presented in Table 2.
2.9.1 Description of Remedy Components
For OU3 (groundwater), eight alternatives were evaluated as part of the FS performed in 1998 and 1999.
Consideration of a "no action" alternative is required by the National Oil and Hazardous Substances
Contingency Plan. However, in the Feasibility Study (Earth Tech/Rust E&I, 1999a), the PP (Earth
Tech/Rust E&I, 1999b), and per the US EPA approved ISA (Robins AFB, 1998), the "no action"
alternative included certain aspects of the Interim Action previously conducted for OU3. In order to
provide an alternative that provides no engineered remedies, a "Baseline Conditions Alternative"
(Alternative 1) was developed as the scenario where "no action" is taken. A summary of the following
alternatives can be found in Table 11. The major components of each alternative are presented below:
Alternative 1: Baseline Conditions Alternative
Institutional controls/LUCs would no longer be maintained.
The OU3 Interim Action groundwater extraction system would be shut down.
Alternative 2: Monitored Natural Attenuation
Institutional controls/LUCs would be maintained to control exposure.
The OU3 Interim Action groundwater extraction system would be shut down.
Natural attenuation mechanisms would reduce COC concentrations to below MCLs.
Natural attenuation parameters and chemical contaminants would be routinely monitored to
determine if natural attenuation was effective.
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Alternative 3a: No Action - Continued Operation of the Existing OU3 Interim Action
The OUS Interim Action groundwater extraction system and treatment system would continue to
operate under current operating conditions.
Groundwater would be periodically monitored to ensure contaminant reductions.
Robins AFB would maintain institutional controls/LUCs to control incidental exposure.
Alternative 3b: Optimized Operation of the Existing OUS Interim Action
The OUS Interim Action groundwater extraction system would be optimized by evaluating the
efficiency and effectiveness of the system. When the evaluation of the data for two groundwater
sampling events indicate that the continued operation of the system is less efficient and effective
than MNA, documentation will be provided by the Air Force to the US EPA and GA EPD to
justify the technical decision for turning off the groundwater extraction system and transitioning
to MNA. The supporting data may include the analytical results, isoconcentration maps,
contaminant trend analyses, groundwater extraction rate data, contaminant mass removal data,
system operating costs, and revised groundwater and transport modeling, as applicable. The
supporting data will sufficiently document the groundwater treatment system's efficiency and
effectiveness. This evaluation, subject to the US EPA and GA EPD review and approval, will
allow for deactivating the OUS groundwater extraction system and transitioning to MNA when it
is determined that MNA is the most appropriate remedial strategy.
Residual contaminants not captured by the system would be reduced by natural attenuation
mechanisms.
Groundwater would be periodically monitored to ensure contaminant reductions.
Robins AFB would maintain institutional controls/LUCs to control incidental exposure.
Alternative 4: Hot Spot Remediation with Monitored Natural Attenuation
The OUS Interim Action groundwater extraction system would be shut down.
Air sparging wells would be installed in the surficial aquifer and Quaternary alluvial aquifer
where elevated concentrations of organics exist (hot spots).
Air sparging system would volatilize the elevated concentrations of organics.
Volatilized organics would migrate with air within the LF04 waste debris/soils and be captured at
soil vapor extraction (SVE) well points.
If necessary, volatile organics would be treated in the air stream via thermal oxidation or other
appropriate means.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
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In addition to the air sparging system, extraction wells would be installed within the surficial
aquifer and Quaternary alluvial aquifer where elevated levels of metals exist.
Extracted groundwater would be treated by an ex-situ, presumed remedy for metals, if necessary.
Residual contaminants in the groundwater not captured by the system would be reduced by
natural attenuation.
Groundwater would be periodically monitored to ensure contaminant reductions.
Robins AFB would maintain institutional controls/LUCs to control incidental exposure.
Alternative 5a: Hot Spot Remediation With Continued Operation Of The Existing OUS Interim Action
Same as Alternative 4 with the exception of continuing to operate the OUS Interim Action
groundwater extraction system.
The OUS Interim Action groundwater extraction system would remain active and operate as
described in the IROD.
All other aspects of hot spot remediation discussed under Alternative 4 would be the same for
Alternative 5a.
Groundwater would be periodically monitored to ensure contaminant reductions.
Robins AFB would maintain institutional controls/LUCs to control incidental exposure.
Alternative 5b: Hot Spot Remediation with Operation of an Optimized OUS Interim Action System
Hot spot removal as indicated in Alternative 4 except that the OUS Interim Action groundwater
extraction system would be optimized to maximize the removal of contaminants.
All other aspects of hot spot remediation discussed under Alternative 4 would be the same for
Alternative 5b.
Groundwater would be periodically monitored to ensure contaminant reductions.
Robins AFB would maintain institutional controls/LUCs to control incidental exposure.
The number of extraction wells would be operated to capture elevated levels of contaminants
while allowing residual contaminants not captured by the system to be reduced by natural
attenuation.
Alternative 6: Extraction of Impacted Groundwater
Alternative 6 would be an attempt to restore aquifers to natural conditions utilizing a completely
engineered extraction system.
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Robins Air Force Base
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Installation of the metals hot spot extraction wells discussed under Alternative 4 would be
included.
Installation of seven new extraction wells near the perimeter of LF04 would be included.
The OUS treatment system discussed in Alternative 3 would be utilized for the treatment of
extracted groundwater under Alternative 6.
Alternative 6 includes a continued monitoring program to verify the reduction in contaminant
concentrations, monitor migration pathways, and evaluate the effectiveness of the extraction
system.
2.9.2 Common Elements and Distinguishing Features of Each Alternative
Common elements distinguishing each alternative are listed below. The evaluation of these elements is
crucial in verifying that the chosen remedy is the best suited for the NPL Site.
KevARARs
For all alternatives evaluated, the chemical- and location-specific ARARs are the same. The chemical-
specific ARAR is remediation of groundwater to drinking water standards (MCLs). The location-specific
ARAR is meeting Georgia water quality standards (WQS) for the natural discharge of OUS groundwater
to the wetlands surface water. An additional location-specific ARAR is the protection of floodplains and
the protection of threatened and/or endangered species. Action-specific ARARs, which differ for each
alternative, are listed below:
Alternative 1: (Baseline Conditions): None
Alternative 2: (Monitored Natural Attenuation): None
Alternative 3a: (No Action - Continued Operation of the Existing OUS Interim Action
Groundwater Extraction System and Treatment System): None ~ The action-specific ARARs
associated with Alternative 3a were managed as part of the OUS Interim Action.
Alternative 3b: (Optimized Operation of the Existing OUS Interim Action Groundwater
Extraction System): Same as alternative 3a.
Alternative 4: (Hot Spot Remediation with Monitored Natural Attenuation): The action-specific
ARARs associated with this alternative include control of air emissions from groundwater
treatment units.
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Alternative 5a: (Hot Spot Remediation with Continued Operation of the Existing OUS Interim
Action Groundwater Extraction System): Same as alternative 4.
Alternative 5b: (Hot Spot Remediation with Operation of an Optimized OUS Interim Action
Groundwater Extraction System): Same as alternative 4.
Alternative 6: (Extraction of Impacted Groundwater): Same as alternative 4.
Long-Term Reliability
The alternatives were also evaluated on long-term reliability or the potential for remedy
failure/replacement costs. If a remediation system is installed, it is expected that it will perform as it has
historically for other sites. Some of the alternatives evaluated included a remediation system
(air sparging) that had a high level for failure based on previous attempts to use this technology at the
NPL Site. Reliability of the alternatives are provided below:
Alternative 1: No Reliability
Alternative 2: Very Low Reliability (MNA only not likely to achieve RAOs)
Alternative 3a: High Reliability (system and performance already proven)
Alternative 3b: High Reliability (system and performance already proven)
Alternative 4: Very Low Reliability (air sparging/SVE previously tried unsuccessfully)
Alternative 5a: Very Low Reliability (air sparging/SVE previously tried unsuccessfully)
Alternative 5b: High Reliability (scaled-up version of proven technology)
Alternative 6: High Reliability
Quantity of Untreated Waste/Degree of Hazards Remaining Due to Containment
The hazards (concentrations) remaining due to containment of OUS (groundwater) is dependent upon the
length of time for cleanup to occur. It should be noted that groundwater modeling performed in the 1999
FS shows that a portion of the metals in the surficial aquifer are not remediated through extraction with
any scenario nor do they migrate off-site since they are bound to the soils in the waste mass through
natural attenuation mechanisms. The longer the estimated cleanup, the higher the concentrations
remaining in the groundwater (OUS) and the greater the risks. The relative risks associated with
contaminants left in OUS are shown below:
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
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Alternative 1: High Risk
Alternative 2: High Risk
Alternative 3a: Medium Risk
Alternative 3b: Medium Risk
Alternative 4: Medium Risk
Alternative 5a: Medium Risk
Alternative 5b: Medium Risk
Alternative 6: Low to Medium Risk
Estimated Time For Design and Construction
Alternative 1: Immediate implementation
Alternative 2: Immediate implementation
Alternative 3a: Immediate implementation
Alternative 3b: Immediate implementation
Alternative 4: 18 Months
Alternative 5 a: 18 Months
Alternative 5b: 18 Months
Alternative 6: 30 Months
Estimated Time To Reach Remediation Goals
Based on modeling performed during the 1999 FS, variations in estimated timeframes to achieve
remediation goals were determined. These comparative timeframes are indicated below:
Alternative 1: Greater than 70 years
Alternative 2: Greater than 50 years
Alternative 3a: Less than 30 years
Alternative 3b: Less than 30 years
Alternative 4: Greater than 40 years
Alternative 5a: Less than 30 years
Alternative 5b: Less than 30 years
Alternative 6: Less than 30 years
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Estimated Capital, Annual O&M, and Present Worth Costs
Alternative 1:
Alternative 2:
Alternative 3 a:
Alternative 3b:
Alternative 4:
Alternative 5 a:
Alternative 5b:
Alternative 6:
Capital: $0
Annual O&M: $0
Present Worth Cost: $76,000
Capital: $0
Annual O&M: $65,000
Present Worth Cost: $882,000
Capital: $1,000,000
Annual O&M: $1,000,000
Present Worth Cost: $11,587,000
Capital: $500,000
Annual O&M: $932,000
Present Worth Cost: $7,042,000 (10 year scenario)
Present Worth Cost: $12,059,000 (30 year scenario)
Capital: $1,800,000
Annual O&M: $124,000
Present Worth Cost: $3,562,000
Capital: $2,800,000
Annual O&M: $1,200,000
Present Worth Cost: $17,914,000
Capital: $2,800,000
Annual O&M: $1,200,000
Present Worth Cost: $17,914,000
Capital: $10,000,000
Annual O&M: $3,000,000
Present Worth Cost: $47,450,000
Use of Presumptive Remedies and/or Innovative Technologies
A presumptive remedy was used for OU1 (LF04 and Sludge Lagoon cap). There were no innovative
technologies (as defined by the US EPA) included in any of the alternatives considered for OU3
(groundwater).
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Robins Air Force Base
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Expected Outcomes Of Each Alternative
Due to the institutional controls/LUCs that will be in place at the NPL Site, it is anticipated that upon
cleanup, the land will continue to be used for non-residential purposes. For purposes of this ROD,
non-residential use excludes uses typically associated with permanent, human habitation, and working
environments but may include uses related to intermittent human contact that pose no threat to human
health or the environment. Because containment with institutional controls/LUCs is the chosen remedy
for OU1, none of the OUS alternatives would remediate the NPL Site to warrant residential land use. A
comparison of the alternatives with respect to groundwater use is shown below:
Alternative 1: Cleanup goals are not likely to be achieved and therefore groundwater would not
be available for future use.
Alternative 2: Cleanup goals are not likely to be achieved and therefore groundwater would not
be available for future use.
Alternative 3a: Cleanup goals are estimated to be achieved in less than 30 years.
Alternative 3b: Cleanup goals are estimated to be achieved in less than 30 years.
Alternative 4: Cleanup of groundwater is not likely due to high risk of failure of remedial method.
Alternative 5a: Cleanup goals are estimated to be achieved in less than 30 years.
Alternative 5b: Cleanup goals are estimated to be achieved in less than 30 years.
Alternative 6: Cleanup goals are estimated to be achieved in less than 30 years.
2.10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Each of the remedial alternatives was evaluated using the nine criteria established by the NCP. The
criteria were derived from the statutory requirements of CERCLA Section 121. The NCP [40 CFR §
300.430 (e) (9)] sets forth nine evaluation criteria that provide the basis for evaluating alternatives and
selecting a remedy.
Table 11 presents a comparative analysis of alternatives. In selecting the preferred alternative, the criteria
referenced in Table 11 were used to evaluate all of the alternatives developed in the FS report (Earth
Tech/Rust E&I, 1999a). Seven of the criteria are used to evaluate all the alternatives based on human
health and environmental protection, cost, and feasibility issues. The alternatives are further evaluated
based on the final two criteria: State acceptance and community acceptance.
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2.11 PRINCIPAL THREAT WASTES
The NCP establishes an expectation that treatment will be used to address the principal threats posed by a
site whenever practicable (NCP § 300.430(a)(l)(iii)(A)). Identifying principal threat wastes that are
source materials considered to be highly toxic or highly mobile which generally cannot be contained in a
reliable manner or would present a significant risk to human health or the environment if exposure occurs.
Conversely, non-principal threat wastes are source materials that generally can be reliably contained and
that would present only a low risk in the event of exposure.
As discussed in previous sections, the OU1 source units have undergone several physical and chemical
treatments in order to reduce the principal threats. The Sludge Lagoon underwent solidification to
immobilize the principal threat wastes. The rest of the LF04 waste mass was not treated due to costs and
the uncertainty of contents. Institutional controls/LUCs were necessary for OU1 since containment and
not treatment was selected as the remedy.
It should be noted that contaminated groundwater is generally not considered to be a source material
unless NAPLs are present. For OUS (groundwater), there are no principal threat wastes as NAPLs have
not been detected at the NPL Site.
2.12 SELECTED REMEDY
The Selected Remedy for OU1 is containment based on presumptive remedies for landfills. Stabilization
was completed for the most contaminated part of OU1 (Sludge Lagoon). For containment, a cap was
installed over OU1 (LF04 and the Sludge Lagoon) in order to reduce infiltration into the waste mass area.
The Selected Remedy for OU1 is no further action with institutional controls/LUCs. At the NPL Site, the
preferred alternative for OUS (groundwater) is "Optimized Operation of the Existing OUS Interim Action
groundwater extraction system with institutional controls/LUCs and a pending transition to MNA, when
appropriate" (Alternative 3b). The subsections below discuss in more detail the Selected Remedy.
2.12.1 Operable Units 1 and 3 Land Use Controls
As used herein, the term "land use control" or "LUC" means "any restriction or control arising from the
need to protect human health and the environment that limits the use of and/or exposure to
environmentally contaminated media (e.g. soils, surface water, ground water) at any site on Robins AFB."
The term includes controls on access (e.g., engineered and non-engineered mechanisms such as fences,
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Robins Air Force Base
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caps, and security guards). Additionally, the term may encompass both affirmative measures to achieve
the desired control (e.g., night lighting of an area) as well as prohibitive directives (e.g., site specific
limitations on digging). Finally, the term could also include "institutional controls" that are non-
engineered mechanisms for ensuring compliance with necessary land use limitations.
The LUC Objective for OU1 is to protect human health and the environment by preventing direct contact
with contaminated soil and solidified sludge under the engineered landfill cover. The LUC Objective for
OUS is to protect human health and the environment by preventing direct contact with, or consumption
of, contaminated groundwater (OUS) by maintaining the integrity of the engineered landfill cover and
restricting access to the groundwater. Access to the groundwater may be permitted for purposes of
further optimizing the groundwater extraction system. Maintenance of the engineered landfill cover
includes preventing excavation activities associated with development and any incompatible land uses.
For both OU1 and OUS, the LUC objectives prohibit the development and use of property for residential
housing, elementary and secondary schools, child care facilities, and playgrounds. The Air Force shall be
responsible for implementing, inspecting, reporting on, and enforcing the LUCs described in this ROD.
The LUCs will be maintained until the concentration of hazardous substances in the soil (OU1) and the
groundwater (OUS) beneath have been reduced to levels that allow for unlimited exposure and
unrestricted use.
Figure 23 indicates where the LUCs are located within the OU1 and OUS areas. Institutional controls
being implemented include the following:
a. Conduct quarterly visual inspections of OU1 where LUCs are implemented for the purpose of
verifying that all necessary LUCs have been implemented and are being properly maintained;
b. Notify the US EPA and the GA EPD as soon as practicable, but no later than 10 days after
discovery of any activity that is inconsistent with the LUC objectives, or use restrictions, or any
action that may interfere with the effectiveness of the LUCs. Any activity that is inconsistent
with the LUC objectives, or use restrictions, or any action that may interfere with the
effectiveness of the LUCs will be addressed by Robins AFB as soon as practicable, but in no case
will the notification process be initiated later than 10 days after Robins AFB becomes aware of
the activity. Robins AFB will notify the US EPA and the GA EPD regarding how Robins AFB
has, or will, address the inconsistent activity within 10 days of sending the US EPA and the GA
EPD notification of the activity;
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c. Prepare and forward an annual report to the US EPA and the GA EPD by June 1 of each year, on
the status of the LUCs, including the operation and maintenance, and monitoring thereof, and
how any LUC deficiencies or inconsistent uses have been addressed. Although the report would
not be subject to approval and/or revision by the US EPA and the GA EPD, the Air Force agrees
to consider and discuss any comments submitted by the US EPA and the GA EPD;
d. Notify the US EPA and the GA EPD at least 60 days in advance of any Base proposals for a
major land use change at a site inconsistent with the use restrictions and assumptions described
herein, any anticipated action that may disrupt the effectiveness of the LUCs, or any action that
might alter or negate the need for LUCs or associated actions. Such changes cannot be
implemented without the US EPA and the GA EPD concurrence;
e. Notify the US EPA and the GA EPD, consistent with CERCLA 120(h), at least six (6) months
prior to any transfer or sale of OU1, including transfers to private, State or local entities, so that
the US EPA and the GA EPD can be involved in discussions to ensure that appropriate provisions
are included in the transfer terms or conveyance documents to maintain effective institutional
controls. If it is not possible for the installation to notify the US EPA and the GA EPD at least
six months prior to any transfer or sale, then Robins AFB will notify the US EPA and the GA
EPD as soon as possible but no later than 60 days prior to the transfer or sale of any property
subject to institutional controls. Robins AFB shall provide the US EPA and the GA EPD a copy
of the executed deed upon request. In addition to the land transfer notice and discussion
provisions above, Robins AFB further agrees to provide the US EPA and the GA EPD with
similar notice, within the same time frames, as to Federal-to-Federal transfer of property
accountability and administrative control of OU1;
f Submittal to the local zoning authority, or the authority with jurisdiction over local land use, a
survey plat indicating the location and dimensions of the LF04 and the Sludge Lagoon source
units (OU1) with respect to permanently surveyed benchmarks. This plat will be prepared by a
professional land surveyor certified in the State of Georgia. The plat, included as part of the Base
Comprehensive Plan and filed with the local zoning authority or the authority with jurisdiction
over local land use, will contain a note, prominently displayed, that provides notice of the
installation's obligation while the Air Force owns the land, to restrict disturbance of OU1 in
accordance with this ROD (e.g., restriction of development construction that would breach the
integrity of the engineered landfill cover). Filing of the survey plat is for notice purposes only
and is not intended, nor does it create, any property interest;
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g. Robins AFB will ensure internal procedures are in place that demonstrate person(s)
knowledgeable regarding any use restrictions associated with LUCs review and approve all
proposed ground disturbing activities, including any well drilling within the source unit areas.
Robins AFB will employ administrative procedures to track all development activity that requires
excavation to ensure that no project violates LUC restrictions for the NPL Site. Air Force
Environmental Management personnel will coordinate and approve all proposed projects located
on or near the NPL Site in accordance with Air Force instructions and procedures. Existing
procedures require the Environmental Management to review and coordinate all Base civil
engineering work requests and to coordinate the "Dig Permit" request process for reviews and
approvals prior to initiating any "ground breaking" work. Through these review and approval
mechanisms, the Air Force will ensure that these or similar instructions, processes, and/or
requirements will be complied with for all proposed construction or surface soil disturbing
activities at the NPL Site;
h. Maintenance of a gate at each entry point to OU1 (LF04 and the Sludge Lagoon source units) in
order to restrict access. It is considered that in order for any human contact to occur with the
LF04 and the Sludge Lagoon source units (waste mass), heavy equipment would be necessary. In
this case, heavy equipment would be required to gain access to OU1 through the two secure gate
access and egress locations indicated on Figure 23. These gates effectively control unauthorized
access to the NPL Site that could result in likely exposure to COCs;
i. Maintenance of signage (1) at each entrance to the LF04 and the Sludge Lagoon source units
(OU1) and (2) at other locations in sufficient numbers to be seen from any likely approach to
OU1. The signs will read "Former Landfill - Authorized Personnel Only - Contact
Environmental Management Regarding Land Use Restrictions" and the current Environmental
Management contact phone number will be displayed. Signs will be posted within 90 days of
obtaining all signatures for the ROD. Signage lettering will be legible from a distance of at least
25 feet; and
j. Prohibition of water supply wells within OUS (i.e. groundwater contaminated by the LF04 and
the Sludge Lagoon source units).
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2.12.2 Summary of Rationale for the Selected Remedy
2.12.2.1 Operable Unit 1 (LF04 and WP14 Sludge Lagoon)
For OU1, the Selected Remedy (presumptive remedy for landfills), as described in the OU1 IROD (IRP,
1991), was containment. As outlined in the ISA (Robins AFB, 1998), any further treatment of the landfill
(LF04) waste mass was not recommended due to the high cost of further treatment or removal and the
uncertainty of the contents within LF04. Because containment was chosen for LF04 as a presumptive
remedy, no other alternatives were presented in the FS or PP for OU1. No Further Action with LUCs has
been proposed as part of this ROD to restrict exposure to remaining contamination and to limit land use.
2.12.2.2 Operable Unit 3 (Groundwater)
As outlined in Table 11, Alternative 3b achieves the desired outcome with minimal tradeoffs with respect
to balancing and modifying criteria. Through groundwater modeling conducted during the 1999 FS, it
was determined that other alternatives, which included more aggressive remediation, did not necessarily
decrease the time to achieve cleanup. Alternative 3b is protective of human health and the environment,
should comply with Federal and State requirements that are applicable or relevant and appropriate to the
remedial action, and is cost effective. Metal COCs appear to be relatively immobile even under the
influence of extraction systems. However, recent data indicates decreasing trends in metal
concentrations, likely attributed to natural attenuation mechanisms, and also decreasing trends in VOC
concentrations (Table 3 and Earth Tech, 2003). Groundwater monitoring would be used concurrently
with and subsequent to this remedy to verify the immobility of the metals and the reduction in their
concentrations through natural attenuation mechanisms, and to evaluate the reductions in VOC
concentrations. When the evaluation of the data for two groundwater sampling events indicate that the
continued operation of the system is less efficient and effective than MNA, documentation will be
provided by the Air Force to the US EPA and GA EPD to justify the technical decision for turning off the
groundwater extraction system and transitioning to MNA. The supporting data may include the analytical
results, isoconcentration maps, contaminant trend analyses, groundwater extraction rate data, contaminant
mass removal data, system operating costs, and revised groundwater and transport modeling, as
applicable. The supporting data will sufficiently document the groundwater treatment system's efficiency
and effectiveness. This evaluation, subject to the US EPA and GA EPD review and approval, will allow
for deactivating the OU3 groundwater extraction system and transitioning to MNA when it is determined
that MNA is the most appropriate remedial strategy. This remedy utilizes permanent solutions and
treatment to the maximum extent practical for the NPL Site.
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2.12.3 Description of Selected Remedy
2.12.3.1 Operable Unit 1 (LF04 and WP14 Sludge Lagoon)
Based on the ISA in 1998, a presumptive remedy for OU1 (landfill capping) was chosen and implemented
prior to developing the FS for the NPL Site. The interim actions listed below are now considered final
remedial actions and include the following:
Initial clay capping of the Sludge Lagoon with a clayey sand cover;
In situ volatilization of the Sludge Lagoon waste mass;
Excavation of the Sludge Lagoon waste mass and solidification;
LF04 cover renovation using geosynthetic fabric and clay liner;
Installation of gas collection system at LF04;
Construction of a new cover over LF04 and the Sludge Lagoon;
Construction of a run-on diversion structure around LF04;
Installation of a leachate collection system at LF04; and
Institutional controls to restrict access and future site use.
Institutional controls are a major component of the Selected Remedy for OU1 and are presented in detail
in Section 2.12.1.
2.12.3.2 Operable Unit 3 (Groundwater)
Under this alternative, the OUS Interim Action groundwater extraction system would be optimized by
maximizing the removal of contaminants more cost effectively, eventually deactivating the system, and
subsequently transitioning to MNA. The OUS groundwater extraction system currently operating would
capture elevated levels of contaminants while allowing residual contaminants not captured by the system
to be reduced by natural attenuation mechanisms. Groundwater would be monitored concurrently and
subsequently to implementation of this alternative to verify the reduction in contaminant concentrations
and the effectiveness of natural attenuation mechanisms.
The optimized OUS Interim Action groundwater extraction system would consist of initially operating the
OUS groundwater extraction system at a rate of approximately 50 gpm each. Through operation of the
OUS groundwater extraction system, most of the organic contamination and some metals will be
captured, thus inhibiting a portion of contaminants in groundwater from potentially discharging to the
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
wetlands, surface water, and sediments. As part of the remedy, the effectiveness of the OUS groundwater
extraction system will be evaluated. When groundwater data indicates that the continued operation of the
OUS groundwater extraction system provides no appreciable benefit over MNA, the system will be turned
off and transitioned to MNA. This evaluation, subject to the US EPA and GA EPD review and approval,
will allow for deactivating the OUS groundwater extraction system and transitioning to MNA when it is
determined that MNA is the most appropriate remedial strategy.
Based on contaminant transport modeling performed in 2003 (Earth Tech, 2004), it is estimated that
cleanup to chemical and location-specific ARARs could occur in a significantly shorter period of time
(possibly less than 10 years) than previously estimated in the FS (30 years) (Earth Tech/Rust E&I,
1999a). The chemical-specific ARAR for the NPL Site OU3 is meeting MCLs that should be attained for
VOCs as indicated by groundwater modeling. It is expected that the Selected Remedy will decrease
metals concentrations in OU3 to attain MCLs through MNA mechanisms. There are two location-
specific ARARs: (1) Georgia WQS standards for the wetlands surface water resulting from the natural
discharge of OU3 groundwater, and (2) the protection of floodplains and threatened and/or endangered
species. The Selected Remedy should meet both these ARARs. The action-specific ARARs for the
Selected Remedy (adherence to the preexisting NPDES permit requirements) has been met with the
current OU3 Interim Action groundwater extraction system. The ARARs should be met in the future with
the optimized OU3 groundwater extraction system because the GWTS is designed to treat the levels of
contamination expected from the optimized system.
Limiting the future use of the site (land and groundwater) through institutional controls is a major
component of the Selected Remedy for OU3. These institutional controls are presented in detail in
Section 2.12.1.
2.12.4 Summary of Estimated Remedy Costs
To date, over $10 million has been spent on containment of OU1. Future costs associated with
implementing LUCs are estimated to be approximately $160,000 (30 year scenario) because institutional
controls are already in place and O&M of such controls would be minimal.
Total "present worth" costs for the Selected Remedy for OU3 are estimated to be between $7,042,000 for
an estimated 10 year operating period (10 year scenario) and $12,059,000 for an estimated 30 year
operating period (30 year scenario). Table 12 includes a more detailed analysis of costs associated with
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
the preferred alternative. Capital costs include a remedial design/groundwater optimization evaluation in
both the scenarios. Annual O&M costs include treatment plant operators, sampling, groundwater data
evaluation, and remedy review. The US EPA guidance suggests that costs are to be presented in terms of
"present worth" in the ROD. Table 12 presents the costs associated with the preferred alternative using
"present worth" in the economic analysis. However, it should be noted that a different economic analysis
using "escalated costs", which includes costs factored for inflation over time, was presented in both the
FS (Earth Tech/Rust E&I, 1999a) and the PP (Earth Tech/Rust E&I, 1999b). Table 13 includes the costs
associated with the remedial alternatives using "escalated costs" in the economic analyses, as presented in
the FS and the PP. Therefore, due to the use of the two different economic analyses for the preferred
alternative, the cost estimates presented in this ROD and in the FS and the PP are not directly comparable
(Table 12 and Table 13).
2.12.5 Expected Outcomes of the Selected Remedy
The expected outcome for the Selected Remedy in terms of resulting land and groundwater uses and risk
reduction achieved as a result of the response action is discussed below. The Selected Remedy for OU1
is containment that does not include a time frame to achieve cleanup levels. LUCs are to be implemented
that will designate the NPL Site as non-residential in the Base Master Plan. By capping the LF04 and the
Sludge Lagoon source units (OU1), infiltration to the source units has been eliminated, and contaminants
leaching to the OU3 groundwater and potentially to surface water have been reduced. Therefore, there
are ecological benefits as a result of implementing containment for OU1.
As discussed in previous sections of this ROD, the RAOs for groundwater (OU3) at the NPL Site are
containment and reduction of contaminants to below MCLs. It is anticipated that groundwater at the NPL
Site will be remediated to the RAOs and that it may be used for drinking water purposes in the future.
However, it should be noted that although the State considers all groundwater potential drinking water,
potable wells have traditionally been installed in the deeper Blufftown aquifer that currently does not
contain COCs related to the NPL Site. It is expected that the Blufftown aquifer will continue to remain
free of COCs throughout the life of the Selected Remedy. It is expected that cleanup of all aquifers will
continue until contaminant levels are below MCLs through treatment and/or natural attenuation
mechanisms.
Based on recent groundwater modeling completed during 2003 (Earth Tech, 2004d), the estimated time
for cleanup could occur in a significantly shorter period of time (possibly less than 10 years) than
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
previously estimated in the FS (30 years) (Earth Tech/Rust E&I, 1999a). Upon completion of cleanup,
groundwater would be available for limited use, although as explained above, potable water is typically
obtained from the Blufftown aquifer, which does not currently contain any COCs related to the NPL Site.
As with OU1, cleanup of the groundwater would reduce the potential for groundwater contamination to
enter the surface water, which provides an ecological benefit to the wetlands downgradient of the NPL
Site.
2.13 STATUTORY DETERMINATIONS
The focus of this ROD is to attain the remedial objectives established. Based on the information currently
available, the USAF and the US EPA in conjunction with the GA EPD believe the selected OU3
(groundwater) remedy (Alternative 3b: Optimized Operation of the Existing OUS Interim Action) meets
the threshold criteria and provides the best balance of tradeoffs among the other alternatives with respect
to the balancing and modifying criteria. Robins AFB expects the Selected Remedy to satisfy the
following statutory requirements of CERCLA §121(b): (1) be protective of human health and the
environment, (2) comply with ARARs, (3) be cost effective, (4) utilize permanent solutions and
alternative treatment technologies or resource recovery technologies to the maximum extent practicable,
and (5) satisfy the preference for treatment as a principal element. Table 13 provides a decision matrix
for the comparison of alternatives that summarizes the ability of each alternative to achieve the statutory
requirements. The following sections discuss how the Selected Remedy meets these statutory
requirements.
2.13.1 Protection of Human Health and the Environment
The RAOs for OU1 are containment and institutional controls/LUCs. Maintenance of the cap on the
LF04 and the Sludge Lagoon source units (OU1) and implementing institutional controls/LUCs will
ensure that all exposure pathways for OU1 are incomplete and/or insignificant. A reevaluation of the risk
remaining at OU1 will be completed during one of the five year reviews or at the time that OU3
(groundwater) is deemed remediated to acceptable levels. It should be noted that the Selected Remedy
would not pose unacceptable short-term risks or cross-media contamination.
The RAOs for OU3 are also containment with institutional controls/LUCs and reduction of contaminants
to below MCLs. The Selected Remedy will be protective of human health and the environment through
the optimized OU3 groundwater extraction and treatment remediation system. MCLs are the chemical-
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
specific ARARs that will be met once the ground-water remediation is complete. The exposure pathways
for OUS groundwater are through ingestion, inhalation, and dermal contact under a future resident
scenario. There are no complete exposure pathways for ecological receptors (current or future). Since
MCLs are the chemical-specific ARARs for OUS, protection of the environment would be accomplished
because MCLs are inherently protective of human health and the environment. This would ensure that all
COCs for OUS are remediated to within the US EPA's acceptable range of 10~4 to 10~6 for carcinogenic
risk and below the HI of 1 for non-carcinogens. Until MCLs have been achieved, LUCs will ensure
exposure pathways for OUS groundwater will remain incomplete. Implementation of the Selected
Remedy will not pose unacceptable short-term risks or cross-media impacts.
2.13.2 Compliance with Applicable or Relevant and Appropriate Requirements
The Selected Remedy for OUS will comply with all ARARs. A detailed discussion of ARARs is found in
the FS (Earth Tech/Rust E&I, 1999a). Table 14 presents a detailed description of all ARARs.
2.13.3 Cost Effectiveness
In the lead agency's judgment, the Selected Remedy for OUS has been determined to provide overall
effectiveness proportional to its costs. Alternative 3b is protective of human health and the environment,
should comply with Federal and State requirements that are applicable or relevant and appropriate to the
remedial action, and is cost effective. This remedy utilizes permanent solutions and treatment to the
maximum extent practical to reduce the toxicity, mobility, and volume of contaminants for the NPL Site.
The estimated present worth cost of the Selected Remedy (Alternative 3b) is between $7,042,000 (10 year
scenario) and $12,059,000 (30 year scenario). Although Alternatives 1 and 2 are less expensive than
either of the Selected Remedy cost scenarios, Alternative 1 is not protective of human health and the
environment and Alternative 2 does not provide a permanent solution. Alternative 3a is less expensive
than the 30 year cost scenario for the Selected Remedy, however, Alternative 3a may leave a higher
residual risk while also not supplying the greater reduced volume and toxicity of contaminated
groundwater.
2.13.4 Use of Permanent Solutions and Alternative Treatment Technologies (or Resource
Recovery Technologies) to the Maximum Extent Practicable
Of the alternatives that are protective of human health and the environment and comply with ARARs, the
USAF has determined that the Selected Remedy provides the best balance of tradeoffs in terms of long-
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
term effectiveness and permanence; reduction in toxicity, mobility, or volume achieved through
treatment; short-term effectiveness; implementability; and cost while also considering the statutory
preference for treatment as a principal element and considering State and community acceptance. The
Selected Remedy is considered to be a permanent solution for both OU1 and OUS.
2.13.5 Preference for Treatment as a Principal Element
Containment with institutional controls/LUCs and not treatment was chosen as the final Selected Remedy
for OU1. Containment was chosen because it is not cost effective to remove and treat a 45-acre landfill.
Containment with institutional controls/LUCs was also chosen for OUS (groundwater). The OUS
groundwater treatment system will provide containment of the groundwater through the extraction,
treatment, and eventual discharge of the effluent to a preexisting NPDES permitted outfall, until the
transition to MNA occurs.
2.13.6 Five Year Review Requirements
The NCP §300.430(f)(4)(ii) requires a five year review if the remedial action results in hazardous
substances, pollutants, or contaminants remaining on-site above levels that allow for unlimited use and
unrestricted exposure. Because containment was selected as a presumptive remedy for OU1, institutional
controls/LUCs are selected in this ROD to compensate for contaminants that remain in the LF04 waste
mass. Therefore, a five year "statutory review" will be required pursuant to CERCLA §121(c) and NCP
§300.430(f)(5)(iii)(C) no less often than every five years until on-site contaminant levels allow for
unlimited use and unrestricted exposure. The first five year review for OU1 will be submitted no later
than five years from final acceptance of this ROD. For OU3, it is estimated that the Selected Remedy
will reduce contaminant levels to below MCLs in 30 years or less. Therefore, a five year "statutory
review" will be required pursuant to CERCLA §121(c) and NCP §300.430(f)(5)(iii)(C) no less often than
every five years until on-site contaminant levels allow for unlimited use and unrestricted exposure. The
first five year review for OU3 will be submitted no later than five years from final acceptance of this
ROD.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
2.14 DOCUMENTATION OF SIGNIFICANT CHANGES FROM PREFERRED
ALTERNATIVE OF PROPOSED PLAN
2.14.1 Operable Unit 1
To fulfill CERCLA §117(b) and NCP §300.430(f)(5)(iii)(B) and §300.430(f)(3)(ii)(A), this ROD must
document and discuss the reasons for any significant changes to the Selected Remedy. Although there
were no changes to the Selected Remedy as a result of the public comment period for the PP, it should be
noted there was an extended period between when the PP was issued for public comment in November of
1999 and fmalization of this ROD. This delay was due to a national policy dispute that developed in
2001 between the Department of Defense and the US EPA Headquarters regarding post-ROD authorities.
In late 2003, both agencies issued agreed-upon guidance to their respective field offices directing a
patterned approach to resolve this dispute. Importantly, the dispute did not substantively affect the
Selected Remedy and has only marginally changed the content of this ROD with the addition of specific
language from the MOA on LUCs entered into by the USAF, the US EPA Region IV, and the GA EPD in
2001. Finally, because (1) the PP only addressed LUCs generally and (2) these same LUCs continue to
be part of the Selected Remedy, the US EPA Region IV and the GA EPD agree that no additional
discussion is warranted for purposes of satisfying NCP 300.430(f)(3)(ii).
2.14.2 Operable Unit 3
The PP (Earth Tech/Rust E&I, 1999b) identified the remedial strategy as Alternative 3b, to optimize the
OU3 Interim Action groundwater extraction system as presented in the OU3 IROD (IRP, 1995b). Since
1999, significant reductions in contaminant concentrations have occurred as a result of implementation
and optimization of the selected IROD remedy for OU3. The contaminant plume concentrations have
been reduced, thereby, allowing for approvals from the US EPA and the GA EPD to discontinue
operation of four of the six OU3 extraction wells. In addition, the leachate and pump stations for the
LF04 toe drain were deactivated in 2002 with prior regulatory approval. The 2003 Annual Progress
Report (Earth Tech, 2004) includes trend plots for TCE that show a downward contaminant concentration
trend for the two OU3 extraction wells currently being pumped. Based on that trend and the data
presented in Table 3, it is anticipated that in the near future, the evaluation of supporting data will indicate
that the continued operation of the system is less efficient and effective than MNA. This evaluation,
subject to the US EPA and GA EPD review and approval, will allow for deactivating the OU3
groundwater extraction system and transitioning to MNA when it is determined that MNA is the most
appropriate remedial strategy.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
3.0 RESPONSIVENESS SUMMARY
The responsiveness summary is intended to provide information about the views of the public and support
agency regarding both the remedial alternatives and general concerns about the site submitted during the
public comment period. The public comment period and public meeting produced several questions as
discussed below. However, the questions and responses did not affect the Selected Remedy.
During the public comment period, there were no written comments on the PP received from the public.
A public meeting was held on February 10, 2000, to present the PP and the preferred alternative to the
community. Several verbal questions were received from one person during the public meeting. The
questions and responses are as shown below. Please note that some of the questions and responses listed
below have been paraphrased for clarity.
Question: What is the timeline for implementation?
Response: The groundwater extraction system has been in operation since October 1997 so in
essence, implementation has already occurred. Once the ROD has been accepted, work
can begin on optimizing the groundwater system. This will require additional modeling
and possibly adjusting the current system. It is anticipated that this can be accomplished
in approximately six months from acceptance of this ROD.
Question: What is the sunset date, or do you have any idea when we are talking about completing
this?
Response: Based upon groundwater modeling completed during the 1999 FS, the estimated time to
cleanup this site is less than 30 years. Most of the contamination would be removed in
the first 10 years with metals taking the longest to reach MCLs. As pointed out earlier in
this document, it may not be feasible to remediate metals contamination in the surficial
aquifer (OU1 waste mass).
Question: How about public concern? Like myself, many people may wonder what would take so
long and are we on track with it. And, so, how do we keep the public adequately
apprised and adequately reassured that remediation is in progress?
Response: Under the current structure there has to be a minimum of a five year review as long as the
site is undergoing remedial action. So every five years Robins AFB would have to go
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
back and review the Selected Remedy to see if it is working, and if it's not, see what
needs to change to meet the remedial action objections. Prior to finalizing the five year
review, Robins AFB would go out with fact sheets and brief members on the Restoration
Advisory Board on the progress. Robins AFB would give the regulatory agencies
periodic copies of what the sampling results are.
Question: Would the public be notified of the five year reviews through media outlets?
Response: Yes, through newspaper print ads and the community relations plan.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
4.0 REFERENCES
CDM Federal Programs, 1992. Supplemental Remedial Investigation, Zone 1, Operable Unit 2,
Robins AFB.
CDM Federal Programs, 1995. Contingency Plan, Zone 1, Operable Unit 2, Robins AFB.
CDM Federal Programs, 1996. Remedial Design Support, Zone 1, Operable Unit 2, Robins AFB.
CH2M Hill, 1990. Final Remedial Investigation Report, Zone 7, Robins AFB, May 1990.
CH2M Hill, 1993. Final Remedial Investigation Report, Zone 1, Operable Unit 3: Groundwater,
Robins AFB, April 1993.
Earth Tech/Rust Environment & Infrastructure (Rust E&I), 1999a. Feasibility Study Report, Zone 1,
Operable Units 1 and 3, Robins AFB. August 1999.
Earth Tech/Rust E&I, 1999b, Draft Final Proposed Plan, The NPL Site, Operable Units 1 and 3, Robins
AFB, November 1999.
Earth Tech/Rust E&I, 1999c, Final Greater Base Industrial Area TCE Groundwater Contamination
(SWMU OT20) Interim Measures and OU3 Groundwater Treatment System 4TH Quarter/Annual
Progress Report Fall 1998, February 1999.
Earth Tech/Rust E&I, 1999d, Final Greater Base Industrial Area TCE Groundwater Contamination
(SWMU OT20) Interim Measures and OUS Groundwater Treatment System Semi-Annual
Progress Report Winter/Spring 1999, October 1999.
Earth Tech/Rust E&I, 2000a, Draft Final Semi-Annual/Annual Progress Report Summer/Fall 1999 for
SWMU 20/OT20 Interim Measures and SWMU 4/LF04 OU3 Groundwater Treatment System,
January 2000.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Earth Tech/Rust E&I, 2000b. Draft Final Baseline Risk Assessment for the Operable Unit 2 Wetlands,
Robins AFB, December 2000.
Earth Tech, 2000a. Draft Final Record of Decision The NPL Site, Operable Units 1 and 3, Robins AFB,
June 2000.
Earth Tech, 2000b. Final Semi-AnnualProgress Report, December 1999 -May 2000, for SWMU20/OT20
Interim Measures; SWMU4/LF04 OU3 Interim Record of Decision; SWMUs 3, 6, and 13/LF03
Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; and Groundwater
Treatment System, Robins AFB, October 2000.
Earth Tech, 200la. Final Semi-Annual/Annual Progress Report, June - November 2000, for SWMU
20/OT20 Interim Measures; SWMU4/LF04 OU3 Interim Record of Decision; SWMUs 3, 6, and
13/LF03 Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; and
Groundwater Treatment System, January 2001.
Earth Tech, 200Ib. Final Semi-Annual Progress Report, December 2000 -May 2001, for SWMU20/OT20
Interim Measures; SWMU4/LF04 OU3 Interim Record of Decision; SWMUs 3, 6, and 13/LF03
Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; and Groundwater
Treatment System, Robins AFB, October 2001.
Earth Tech, 2003. Final Groundwater Sampling, Spring 2003 for Delivery Order 5041, Warner Robins
Air Logistics Center, Robins AFB, Georgia, December 2003.
Earth Tech, 2004a. Final Semi-Annual/Annual Progress Report, June - November 2001, for SWMU
20/OT20 Interim Measures; SWMU4/LF04 OU3 Interim Record of Decision; SWMUs 3, 6, and
13/LF03 Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; and
Groundwater Treatment System, Robins AFB, January 2004.
Earth Tech, 2004b. Final Annual Progress Report, December 2001 - November 2002, for SWMU4/LF04
OU3 Interim Record of Decision; SWMU 20/OT20 Corrective Action Plan; SWMUs 3, 6, and
13/LF03 Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; SWMU 62/OT37
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Corrective Action Plan; SWMUs 57 and 61/OT41 Corrective Action Plan; and Groundwater
Treatment System, Robins AFB, January 2004.
Earth Tech, 2004c, Final Annual Progress Report, December 2001 - November 2002, for SWMU4/LF04
OU3 Interim Record of Decision; SWMU 20/OT20 Corrective Action Plan; SWMUs 3, 6, and
13/LF03 Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; SWMU 62/OT37
Corrective Action Plan; SWMUs 57 and 61/OT41 Corrective Action Plan; and Groundwater
Treatment System, Robins AFB, January, 2004.
Earth Tech, 2004d. Draft Annual Progress Report, December 2002 - November 2003, for SWMU4/LF04
OU3 Interim Record of Decision; SWMU 20/OT20 Corrective Action Plan; SWMUs 3, 6, and
13/LF03 Corrective Action Plan; SWMUs 17 and 24/OT17 Corrective Action Plan; SWMU 62/OT37
Corrective Action Plan; SWMUs 57 and 61/OT41 Corrective Action Plan; and Groundwater
Treatment System, Robins AFB, February 2004.
Electronic Handbook Publishers, Inc., 2000. Electronic Handbook of Risk Assessment Values (EHRAV).
Electronic Database. Bellvue, WA. April 2000.
Environmental Chemical Corporation (ECC), 1997. Draft Final Remedial Action Work Plan, Cover
Renovation of Landfill 04, Robins AFB, August 1997.
IRP, 1991. Interim Record of Decision, Robins Air Force Base, Zone 1, Operable Unit 1, June 1991.
IRP, 1995b. Interim Record of Decision, Robins Air Force Base, Zone 1, Operable Unit 3, September
1995.
Robins AFB, 1998. Initial Screening of Alternatives, Operable Units 1 & 3, Robins AFB, November
1998.
Rust E&I, 1998a. Basewide Groundwater Sampling, Spring 1998, Robins AFB, September 1998.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
Rust E&I, 1998b. Final Greater Base Industrial Area TCE Groundwater Contamination (SWMU OT20)
Interim Measures and OUS Groundwater Treatment System 2ND Quarter Progress Report Spring
1998, October 1998.
Rust E&I, 1998c. Final Greater Base Industrial Area TCE Groundwater Contamination (SWMU OT20)
Interim Measures and OUS Groundwater Treatment System 3RD Quarter Progress Report
Summer 1998, October 1998.
Rust E&I, 1999. Final Groundwater Treatment System 1ST Quarter Report Winter 1998, April 1999.
US EPA, 1986. Superfund Public Health Evaluation Manual (SPHEM). Office of Emergency and
Remedial Response, Washington, DC. EPA/540/1-86/060. October 1986.
US EPA, 1988. Integrated Risk Information System (IRIS). "Chemical Files" and "Background
Information" from US EPA IRIS Database. Office of Research and Development, Cincinnati,
Ohio.
US EPA, 1989a. EPA Risk Assessment Guidance for Superfund (RAGS): Vol. 1, Human Health
Evaluation Manual, Part A. Office of Emergency and Remedial Response, Washington, DC.
US EPA/5401-89/002. December 1989.
US EPA, 1989b. Exposure Factors Handbook, Final Report. EPA/600/8-89/043. Office of Health and
Environmental Assessment, Washington, D.C. March 1989.
US EPA, 1989c. Health Effects Assessment Summary Tables (HEAST). Office of Research and
Development. Washington, DC.
US EPA, 1990a. Exposure Factors Handbook. Office of Health and Environmental Assessment.
Washington, D.C. March 1990.
US EPA, 1990b. National Oil and Hazardous Substance Pollution Contingency Plan. Federal Register
55: 8666-8865.
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Final Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
US EPA, 1992a. Integrated Risk Information System (IRIS). Office of Research and Development.
Washington, DC. February 1992.
US EPA, 1992b. Health Effects Assessment Summary Tables (HEAST). Office of Research and
Development, US EPA, Washington, DC. February 1992.
US EPA, 1996. Drinking Water Regulations and Health Advisories. EPA/822-B-96-002. Office of
Water, Washington, DC, October 1996.
US EPA, 2000a. Supplemental Guidance to RAGS: Region IV Bulletins - Human Health Risk
Assessment, Interim. Waste Management Division, Office of Health Assessment, US EPA
Region IV, Atlanta, GA. May 2000.
US EPA, 2000b. Risk-Based Concentration Table. April 13, 2000. Region III Superfund Technical
Support Section, Philadelphia, PA. April 2000.
US EPA, 2003a. US EPA National Primary Drinking Water Standards, MCLs, EPA 816-F-03-016.
Office of Water, Washington, DC, June 2003.
US EPA, 2003a. US EPA Position Letter Operable Unit 2, Wetlands, Robins AFB, Warner Robins,
Georgia, August 2003.
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Table 1
Prevalent Chemicals Found in Source Area OU1 During Remedial Investigation
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Maximum Level MCL (jig/L)
Source Area
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
WP14 Sludge Lagoon
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Landfill No. 4
Chemical of Concern
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
1 , 1 -Dichloroethene
1 ,2-Dichlorobenzene
cis- 1 ,2-Dichloroethene
1 ,4-Dichlorobenzene
Benzene
Chlorobenzene
Methylene Chloride
Tetrachloroethene
Toluene
Trichloroethene
Vinyl Chloride
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
1 ,4-Dichlorobenzene
Benzene
Chlorobenzene
Methylene Chloride
Trichloroethene
Vinyl Chloride
Detected
(Hg/L)1
21,000
34,800
13,163,000
10,600
60,000
85
15,000
100
28,000
36,000
13,000
660
4,000
6,000
1,100
2,200
130,000
12,000
13,000
9,300
66,000
3,600
10,400
880
1,300
120
85
150
110
8
12
as of
October 19962
50
5
100
1300 (TT5)
15 (TT5)
2
100
7
600
70
75
5
100
5
5
1,000
5
2
50
5
100
1300 (TT5)
15 (TT5)
2
100
75
5
100
5
5
2
MCL (ug/L)
as of
Summer 20003
5
5
100
1300 (TT5)
15 (TT5)
2
NA
7
600
70
75
5
100
5
5
1,000
5
2
5
5
100
1300 (TT5)
15 (TT5)
2
NA
75
5
100
5
5
2
Type and
Characteristic
i,c
I,N
I,N
I,N
I,*
I,*
I,N
M,N
M,N
M,N
M,C
M,C
M,N
M,C
M,C
M,N
M,C
M,C
i,c
I,N
I,N
I,N
I,*
I,*
I,N
M,N
M,C
M,N
M,C
M,C
M,C
Notes:
ug/L = micrograms per liter MCL = maximum contaminant level
TT =Treatment Technique NA = Not Applicable (MCL not available for this chemical)
I = immobile; M = mobile; C = carcinogenic; N = noncarcinogenic; * = data not available
1 Chemicals of Concern for the Sludge Lagoon and LF04 are prior to any interim actions and are based
on 1990 data collected and reported by CH2MHill from leachate and surficial well samples.
Chemical-specific groundwater MCLs based on Drinking Water Regulations and Health Advisories, EPA 822-B-96-002
(US EPA, October 1996) EXCEPT FOR Lead and Copper which are "at tap" action levels (see note 5 below). The 1996 MCL values were
used in the development of the COCs, FS, and final remedy selection.
Chemical-specific groundwater MCLs based on Drinking Water Regulations and Health Advisories, EPA 816-F-03-016
(US EPA, Summer 2003) EXCEPT FOR Lead and Copper which are "at tap" action levels (see note 5 below).
Based on groundwater modeling completed during the FS (Earth Tech/Rust E & I, February 1999), metals in the surficial aquifer are
generally immobile; carcinogenity based upon US EPA Region 3 Risk-Based Concentration (RBC) Table, Tap Water (US EPA, April 2000).
Copper "at tap" action level is 1300 ug/L; Lead "at tap" action level is 15 ug/L.
l:\work\projects\75279\wordproc\FinalROD\Tables 1_2 rev01.xls
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Table 2
Summary of Chemicals of Concern for OU3 Groundwater
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Aquifer (unit)
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Quaternary
Quaternary
Quaternary
Quaternary
Quaternary
Upper Providence
Upper Providence
Upper Providence
Chemical of Concern
Arsenic
Cadmium
Chromium
Lead
Benzene
Chlorobenzene
cis- 1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
Carbon Tetrachloride
Chlorobenzene
Tetrachloroethene
Trichloroethene
Vinyl chloride
Carbon Tetrachloride
Tetrachloroethene
Trichloroethene
Maximum
Detected
(Hg/L)1
394
45.3
57.3
113
100
450
1,300
54
590
38
850
150
840
170
38
150
840
MCL (ug/L)
as of
October 19962
50
5
100
15 (TT5)
5
100
70
5
5
5
100
5
5
2
5
5
5
MCL (ug/L)
as of
Summer 20033
5
5
100
15 (TT5)
5
100
70
5
5
5
100
5
5
2
5
5
5
Type and
Characteristic
i,c
I,N
I,N
I,*
M,C
M,N
M,N
M,C
M,C
M,C
M,N
M,C
M,C
M,C
M,C
M,C
M,C
MCL = maximum contaminant level
Notes:
Hg/L = micrograms per liter
LL =Lreatment Technique
I = immobile; M = mobile; C = carcinogenic; N = noncarcinogenic; * = data not available
Maximum detected concentration of chemical in groundwater samples based upon Spring 1998
basewide groundwater sampling event data (Rust E&I, 1998).
Chemical-specific groundwater MCLs based on Drinking Water Regulations and Health Advisories, EPA 822-B-96-002
(US EPA, October 1996) EXCEPT FOR Lead which is an "at tap" action level (see note 5 below). The 1996 MCL values were
used in the development of the COCs, FS, and final remedy selection.
Chemical-specific groundwater MCLs based on Drinking Water Regulations and Health Advisories, EPA 816-F-03-016
(US EPA, Summer 2003) EXCEPT FOR Lead which is an "at tap" action level (see note 5 below).
Based on groundwater modeling completed during the FS (Earth Tech/Rust E&I, February 1999), metals in the surficial aquifer are
generally immobile; carcinogenity based upon US EPA Region 3 Risk-Based Concentration (RBC) Table, Tap Water (US EPA, April 2000).
Lead "at tap"action level is 15
l:\work\projects\75279\wordproc\FinalROD\Tables 1_2 rev01.xls
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Table 3
Current Concentrations for Chemicals of Concern for OU3 Groundwater
Comparison to MCLs and Historic Concentrations
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Aquifer (unit)
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Surficial
Quaternary
Quaternary
Quaternary
Quaternary
Quaternary
Upper Providence
Upper Providence
Upper Providence
Chemical of Concern
Arsenic
Cadmium
Chromium
Lead
Benzene
Chlorobenzene
cis-1 ,2-Dichloroethene
Tetrachloroethene
Trichloroethene
Carbon Tetrachloride
Chlorobenzene
Tetrachloroethene
Trichloroethene
Vinyl Chloride
Carbon Tetrachloride
Tetrachloroethene
Trichloroethene
Maximum Detected
Concentration (u,g/L)
Spring 1998 l
394
45.3
57.3
113
100
450
1300
54
590
38
850
150
840
170
38
150
840
Spring 2003 2
102
0.38 J
14.2
6.85
76
210
ND
0.14J
0.19J
25
1100
55
160
270
73
190
490
Well ID 3
LSB15
LF4-44
LSB15
LSB15
LSB13
LSB14
-
LF4-28
LF4-28
LF4-30
LF4-6
LF4WP9
LF4-6
LF4-6
PJ1-2W
PJ1-2W
PJ1-2W
MCL (ug/L)
as of
Summer 2003 4
5
5
100
15(TT5)
5
100
70
5
5
5
100
5
5
2
5
5
5
Notes:
Hg/L = micrograms per liter
TT = treatment technique
J = estimated concentration
MCL = maximum contaminant level
ND = not detected
- = not applicable
Maximum detected concentration of chemical in groundwater samples based upon Spring 1998
basewide groundwater sampling event data (Rust E&I, 1998).
Maximum detected concentration of chemical in groundwater samples based upon Spring 2003
basewide groundwater sampling event data (Earth Tech, 2003).
Well IDs apply to the Spring 2003 concentrations.
Chemical-specific groundwater MCLs based on Drinking Water Regulations and Health Advisories, EPA 816-F-03-016
(US EPA, Summer 2003) EXCEPT FOR Lead which has an "at tap" action level (see note 5 below).
Lead "at tap" action level is 15 ng/L.
L:\work\projecti\75279\WordProc\FinalROD\Table3 new rev01.xls
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Table 4
Summary of Chemicals of Concern and
Medium-Specific Exposure Point Concentrations - Groundwater1
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins Air Force Base, Georgia
Scenario Timeframe: Future
Medium: Groundwater 2
Exposure Medium: Groundwater and Water Vapors 2
Exposure Point
On-Site Resident
Quaternary Alluvial Aquifer
.ngestion and
inhalation of Water Vapors
Chemical of Concern3
VOCs
Benzene
Butanone, 2-
Carbon tetrachloride
Chlorobenzene
Chloroform
Dichlorobenzene, 1 ,2-
Dichlorobenzene, 1 ,4-
Dichloroethene, 1,2-
Dichloropropene, trans-1,3-
Tetrachloroethene
Tnchloroethane, 1,1,1-
Tnchloroethene
Vinyl chloride
PAHs
Dimethylphenol, 2,4-
Methylphenol, 2-
Methylphenol, 4-
Metals
Aluminum
Arsenic
Beryllium
Cadmium
Copper
Manganese
Mercury
Nickel
Thallium
Vanadium
Pesticides
Dieldrin
Concentration Detected 4
Minimum
2.00E+00
2.50E+01
l.OOE+00
2.00E+00
l.OOE+00
4.00E+00
4.00E+00
2.00E+00
5.00E+00
l.OOE+00
l.OOE+00
l.OOE+00
l.OOE+00
ND
ND
ND
8.29E+01
6.00E-01
2.00E-01
6.20E+00
3.10E+00
7.50E+00
l.OOE-01
1.41E+01
2.00E+00
5.40E+00
l.OOE-02
Maximum
2.00E+00
1.10E+02
7.00E+01
l.OOE+01
1.90E+02
5.00E+00
8.00E+00
3.40E+01
5.00E+00
3.30E+02
l.OOE+00
5.90E+02
l.OOE+00
ND
ND
ND
5.00E+04
1.60E+00
2.90E+00
1.62E+01
1.68E+02
4.63E+02
9.70E+00
8.33E+01
2.00E+00
1.01E+02
3.50E-02
Mean
2.00E+00
5.24E+01
l.OOE+01
5.90E+00
6.90E+00
4.60E+00
6.70E+00
8.60E+00
5.00E+00
9.70E+00
l.OOE+00
3.92E+01
l.OOE+00
ND
ND
ND
6.17E+03
9.00E-01
5.00E-01
l.OOE+01
2.74E+01
8.88E+01
8.00E-01
2.88E+01
2.00E+00
2.54E+01
1.70E-02
Units
re'L
re'L
re/L
re/L
re/L
re/L
re'L
re'L
re/L
re/L
re'L
re'L
re/L
re/L
re/L
re'L
re/L
re/L
re'L
re'L
re/L
re/L
re'L
re'L
re/L
re/L
re'L
Frequency of
Detection 5
5%
5%
60%
17%
60%
7%
10%
55%
2%
57%
2%
91%
2%
ND
ND
ND
98%
15%
26%
5%
71%
98%
45%
41%
2%
74%
52%
Exposure Point
Concentration 6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Exposure Point
Concentration
Units
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Statistical
Measure 6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
l:\work\prqjects\75279\wordprocWinalROD\TaUe4 revOLxls
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Table 4
Summary of Chemicals of Concern and
Medium-Specific Exposure Point Concentrations - Groundwater1
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins Air Force Base, Georgia
Scenario Timeframe: Future
Medium: Groundwater 2
Exposure Medium: Groundwater and Water Vapors 2
Exposure Point
On-Site Resident
Upper Providence Unit
.ngestion and
inhalation of Water Vapors
On-Site Resident
Lower Providence Unit
.ngestion and
.nhalation of Water Vapors
Chemical of Concern3
VOCs
Bromomethane
Butanone, 2-
Carbon tetrachloride
Chloroform
Dichloroethene, 1,1-
Dichloropropene, trans-1,3-
Tetrachloroethene
Tnchloroethane, 1,1,1-
Trichloroethene
PAHs
Dinitrophenol, 2,4,-
Metals
Arsenic
Beryllium
Cadmium
Thallium
Vanadium
Zinc
Dieldrin
VOCs
Bromomethane
Dichloropropene, trans-1,3-
Trichloroethene
PAHs
Dinitrophenol, 2,4-
Metals
Arsenic
Beryllium
Cadmium
Zinc
Pesticides
Dieldrin
Concentration Detected 4
Minimum
l.OOE+01
1.40E+02
l.OOE+00
l.OOE+00
l.OOE+00
5.00E+00
l.OOE+00
l.OOE+00
l.OOE+00
5.00E+01
6.00E-01
2.00E-01
3.80E+00
ND
3.20E+00
7.70E+00
1.10E-02
l.OOE+01
5.00E+00
l.OOE+00
5.00E+01
6.00E-01
l.OOE-01
4.60E+00
4.70E+00
9.00E-03
Maximum
l.OOE+01
2.90E+02
1.20E+02
1.50E+01
l.OOE+00
5.00E+00
8.50E+01
4.00E+00
1.20E+03
5.00E+01
1.30E+00
7.00E-01
1.15E+01
ND
5.25E+01
1.07E+02
6.80E-02
l.OOE+01
5.00E+00
l.OOE+01
5.00E+01
8.00E-01
5.00E-01
4.60E+00
5.24E+01
5.00E-02
Mean
l.OOE+01
1.98E+02
7.40E+00
1.60E+00
l.OOE+00
5.00E+00
8.70E+00
2.30E+00
2.60E+01
5.00E+01
9.00E-01
4.00E-01
5.30E+00
ND
1.12E+01
2.73E+01
2.60E-02
l.OOE+01
5.00E+00
2.40E+00
5.00E+01
7.00E-01
3.00E-01
4.60E+00
2.14E+01
2.60E-02
Units
re'L
re'L
re/L
re/L
re/L
re/L
re'L
re'L
re/L
re/L
re'L
re'L
re/L
re/L
re'L
re'L
re/L
re'L
re/L
re/L
re/L
re'L
re'L
re/L
re/L
re/L
Frequency of
Detection 5
3%
9%
50%
22%
3%
3%
28%
9%
59%
3%
13%
25%
13%
ND
53%
66%
38%
5%
5%
30%
5%
17%
30%
5%
65%
15%
Exposure Point
Concentration 6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Exposure Point
Concentration
Units
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Statistical
Measure 6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
l:\work\projects\75279\wordprocWinalROD\TaUe4 revOLxls
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Table 4
Summary of Chemicals of Concern and
Medium-Specific Exposure Point Concentrations - Groundwater1
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins Air Force Base, Georgia
Scenario Timeframe: Future
Medium: Groundwater 2
Exposure Medium: Groundwater and Water Vapors 2
Exposure Point
On-Site Resident
Blufftown and Cusseta Aquifer
ngestion
Chemical of Concern3
Metals
Arsenic
Beryllium
Cadmium
Thallium
Zinc
Concentration Detected 4
Minimum
3.00E+00
2.00E-01
1.03E+01
ND
4.09E+01
Maximum
9.30E+00
2.00E-01
1.03E+01
ND
7.83E+04
Mean
4.50E+00
2.00E-01
1.03E+01
ND
2.77E+02
Units
re/L
Mg-'L
ug/L
ug/L
K/L
Frequency of
Detection 5
23%
8%
8%
ND
100%
Exposure Point
Concentration 6
NA
NA
NA
NA
NA
Exposure Point
Concentration
Units
NA
NA
NA
NA
NA
Statistical
Measure 6
NA
NA
NA
NA
NA
Notes:
- Information presented in this table obtained from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Groundwater, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
- Potential groundwater and water vapor exposures from hypothetical potable groundwater wells in Quatenary Alluvial/Unconfined Upper Providence, Confined Upper Providence, Lower Providence and Blufftown/Cusseta aquifers.
3 - Chemicals of Concern (COCs) are identified as those chemicals which significantly contribute to total cancer risk greater than 10 ^ or total hazard index (HI) greater than 1.
4 - Concentrations are reported in the BRA based upon minimum, maximum, and geometric mean values for comparison purposes.
- Frequency of detection based upon percent detection of total number of samples.
- Exposure point concentration is based upon the maximum detected concentration (MAX) on a per-well basis, as presented in Table 12.
- Concentrations are based upon site media concentrations for groundwater from landfill monitoring wells; ingestion exposures for all COCs and inhalation exposures for VOCs only.
ug/L - micrograms per liter
NA - not applicable
ND - no data documented in the BRA Report
VOCs - volatile organic compounds
PAHs - polynuclear aromatic hydrocarbons
l:\work\projects\75279\wordproc\FmalROD\Table4revOLxls
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Table 5
Cancer Toxicity Data - Oral/Dermal
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
MAY 1990 BRA1
PAHs
3enzo(a)anthracene
3enzo(a)pyrene
3enzo(b)fluoranthene
Benzo(g,h,i)perylene 5
3enzo(k)fluoranthene
Chrysene 5
Dibenz(a,h)anthracene
lndeno(l,2,3)pyrene 5
Metals
Arsenic
Desticides
Dieldrm
APRIL 1993 BRA2
VOCs
3enzene
Carbon tetrachloride
Chloroform
Dichloropropene, trans-1,3-
retrachloroethene
rnchloroethane, 1,1,1-
rnchlorethene
Vinyl chloride
Oral
Cancer
Slope Factor
11.5
11.5
11.5
11.5
11.5
11.5
11.5
11.5
1.75
16
0.029
0.13
0.0061
0.18
0.052
ND
0.011
1.9
Dermal
Cancer
Slope Factor 3
11.5
11.5
11.5
11.5
11.5
11.5
11.5
11.5
NA
16
NA
NA
NA
NA
NA
NA
NA
NA
Units
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
l/(mg/kg/d)
l/(mg/kg/d)
l/(mg/kg/d)
l/(mg/kg/d)
l/(mg/kg/d)
ND
l/(mg/kg/d)
l/(mg/kg/d)
Weight of Evidence/
Cancer Guideline
Description 4
B2
B2
B2
B2
B2
C
B2
B2
A
B2
A
B2
B2
B2
B2
ND
B2
A
Source
SPHEM
SPHEM
SPHEM
SPHEM
SPHEM
SPHEM
SPHEM
SPHEM
HEAST
IPJS
IPJS
IPJS
IPJS
HEAST
HEAST
ND
IPJS
HEAST
Date
(MM/DD/YY)
10/01/86
10/01/86
10/01/86
10/01/86
10/01/86
10/01/86
10/01/86
10/01/86
04/01/89
09/07/88
02/92
02/92
02/92
02/92
02/92
ND
02/92
02/92
Notes:
NA - Not applicable (only carcinogenic COCs in sediment were identified for the dermal exposure pathway).
ND - No data documented in BRA Report.
1 - Data from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
IRIS - Integrated Risk Information System (EPA, 1988).
HEAST - Health Effects Assessment Summary Tables-Quarterly Summary (EPA, 1989).
SPHEM - Superfund Public Health Evaluation Manual (EPA, 1986).
2 - Data from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
Sources:
IRIS - Integrated Risk Information System (EPA, February 1992a).
HEAST - Health Effects Assessment Summary Tables-Quarterly Summary (EPA, February 1992b).
- SFs were not available for the dermal route of exposure; therefore, oral SFs were also used to represent dermal SFs.
4 -EPA Group:
A - Human carcinogen.
Bl - Probable human carcinogen - indicates that limited human data are available.
B2 - Probable human carcinogen - indicates sufficient evidence in animals and inadequate or no evidence in humans.
C - Possible human carcinogen.
- Surrogate values based on benzo(a)pyrene.
l:\work\projects\75279\wordproc\FinalROD\Table5rev01.xls
sm
10/14/2004
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Table 6a
Cancer Toxicity Data - Inhalation (from BRA Reports)
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
MAY 1990 BRA1
VOCs
Chloroform
Metals
Arsenic
Cadmium
Chromium 4
Unit Risk
ND
ND
ND
ND
Units
ND
ND
ND
ND
Inhalation Cancer
Slope Factor
0.081
50
6.1
41
Units
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
Weight of Evidence/
Cancer Guideline
Description 3
B2
A
Bl
A
Source
IRIS
IRIS
IRIS
IRIS
Date
(MM/DD/YY)
06/30/88
12/01/88
03/01/88
03/01/88
APRIL 1993 BRA2
VOCs
Benzene
Carbon tetrachloride
Chloroform
Dichloropropene, trans-1,3-
letrachloroethene
rrichloroethane, 1,1,1-
rrichloroethene
Vinyl Chloride
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Notes:
ND - No data documented in BRA Report.
1 - Data from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
Sources:
IRIS - Integrated Risk Information System (EPA, 1988).
- Data from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
3 -EPA Group:
A - Human carcinogen.
Bl - Probable human carcinogen - indicates that limited human data are available.
B2 - Probable human carcinogen - indicates sufficient evidence in animals and inadequate or no evidence in humans.
- Toxicity data for total chromium was based on surrogate values for hexavalent chromium.
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Table 6b
Additional Cancer Toxicity Data - Inhalation 1
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
Unit Risk
Units
Inhalation Cancer
Slope Factor
Units
Weight of Evidence/
Cancer Guideline
Description 4
Source
Date5
(MM/DD/YY)
MAY 1990 BRA 2
VOCs
Chloroform
Metals
Arsenic
Cadmium
Chromium 6
2.3E-05
4.3E-03
1.8E-03
1.2E-02
(ug/m3)-l
(ug/m3)-l
(ug/m3)-l
(ug/m3)-l
8.1E-02
1.5E+01
6.3E+00
4.2E+01
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
B2
A
Bl
A
IRIS
IRIS
IRIS
IRIS
09/12/00
09/12/00
09/12/00
09/12/00
APRIL 1993 BRA 3
VOCs
Benzene
Carbon tetrachloride
Chloroform
Dichloropropene, trans-1,3-
letrachloroethene
rrichloroethane, 1,1,1-
rrichloroethene
Vinyl Chloride
7.8E-06
1.5E-05
2.3E-05
4.0E-06
5.8E-07
NA
1.7E-06
4.4E-06
(ug/m3)-l
(ug/m3)-l
(ug/m3)-l
(ug/m3)-l
(ug/m3)-l
NA
(ug/m3)-l
(ug/m3)-l
2.7E-02
5.3E-02
8.1E-02
1.4E-02
2.0E-03
NA
6.0E-03
1.5E-02
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
kg-day/mg
NA
kg-day/mg
kg-day/mg
A
B2
B2
B2
C-B2
D
C-B2
A
IRIS
IRIS
IRIS
IRIS
NCEA
IRIS
NCEA
IRIS
09/12/00
09/12/00
09/12/00
09/12/00
4/13/2000
09/12/00
4/13/2000
09/12/00
Notes:
1 - Toxicity data presented in this table was not obtained from the BRA Reports;
however, this information is provided in order to present all current available toxicological data for site-related COCs.
- COCs from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
3 - COCs from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2MHill, April 1993).
4 -EPA Group:
A - Human carcinogen.
Bl - Probable human carcinogen - indicates that limited human data are available.
B2 - Probable human carcinogen - indicates sufficient evidence in animals and inadequate or no evidence in humans
C - Possible human carcinogen
5 - For IRIS values, the date IRIS was searched.
For NCEA values, the date of EPA Region III Risk-Based Concentration Table.
- Toxicity data for total chromium was based on surrogate values for hexavalent chromium.
- Toxicity data for trans-l,3-dichloropropene was based on surrogate values for 1,3-dichloropropene.
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Table 7 a
Non-Cancer Toxicity Data - Oral/Dermal (from BRA Reports)
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
Chronic/
Subchronic
Oral RfD
Value
Oral RfD
Units
Dermal
RfD
Units
Primary
Target
Organ
Combined
Uncertainty /Modifying
Factors
Sources of RfD:
Target Organ
Dates of RfD:
Target Organ
(MM/DD/YY)
MAY 1990 BRA1
Metals
Arsenic
Cadmium
Chromium
ND
ND
ND
ND
0.0005
0.005
ND
mg/kg/day
mg/kg/day
NA
NA
NA
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
HEAST
IRIS
ND
04/01/89
03/01/88
APRIL 1993 BRA2
VOCs
3romom ethane
3utanone, 2-
Carbon tetrachloride
Chlorobenzene
Dichloroethene, 1,2-
letrachloroethene
Irichloroethene
PAHs
Dimethylphenol, 2,4-
Dinitrophenol, 2,4-
Vlethylphenol, 2
Vlethylphenol, 4
Metals
Aluminum
Arsenic
Cadmium
Copper
Vlanganese
Vlercury
Nickel
Iha Ilium
Vanadium
Zinc
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.0014
0.05
0.0007
0.02
0.01
0.01
0.006
0.02
0.002
0.05
0.05
2.9
0.0003
0.0005
0.0371
0.1
0.0003
0.02
ND
0.007
0.2
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
IRIS
HEAST
IRIS
IRIS
HEAST
IRIS
EPA-ECAO
IRIS
IRIS
IRIS
HEAST
ND
IRIS
IRIS
HEAST
IRIS
HEAST
IRIS
ND
HEAST
HEAST
1992
1992
1992
1992
1992
1992
ND
1992
1992
1992
1992
ND
02/92
02/92
02/92
02/92
02/92
02/92
02/92
02/92
02/92
Notes:
NA - Not applicable (noncarcinogenic COCs were not identified for the dermal exposure pathway).
ND - No data documented in BRA Report.
1 - Data from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
Sources:
IRIS - Integrated Risk Information System (EPA, 1988).
HEAST - Health Effects Assessment Summary Tables-Quarterly Summary (EPA, 1989).
"Data from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
Sources:
IRIS - Integrated Risk Information System (EPA, February 1992a).
HEAST - Health Effects Assessment Summary Tables-Quarterly Summary (EPA, February 1992V
EPA-ECAO - Environmental Criteria Assessment Office
- Toxicity data for total chromium was based on surrogate values for hexavalent chromium.
/: \work\projects\75279\wordproc\FinalROD\Table7a re
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Table 7b
Additional Non-Cancer Toxicity Data - Oral/Dermal
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
Chronic/
Subchronic
Oral RfD
Value 4
Oral RfD
Units
Dermal
RfD
Units
Primary
Target
Organ
Combined
Uncertainty/Modifying
Factors 5
Sources of RfD:
Target Organ
Dates of RfD:
Target Organ
(MM/DD/YY)
MAY 1990 BRA 2
Metals
Arsenic
Cadmium
Chromium3
APRIL 1993 BRA 3
VOCs
3romomethane
3utanone, 2-
Carbon tetrachloride
Chlorobenzene
Dichloroethene, 1,2-
letrachloroethene
rrichloroethene
PAHs
Dimethylphenol, 2,4-
Dinitrophenol, 2,4-
Methylphenol, 2
Vlethylphenol, 4
Metals
Aluminum
Arsenic
Cadmium
Copper
Viang anese
Vlercury
Nickel
Thallium
Vanadium
Zinc
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
3.00E-04
5.00E-04
3.00E-03
1.40E-03
6.00E-01
7.00E-04
2.00E-02
9.00E-03
l.OOE-02
6.00E-03
2.00E-02
2.00E-03
5.00E-02
5.00E-03
l.OOE+00
3.00E-04
5.00E-04
3.70E-02
2.38E-02
3.00E-04
2.00E-02
8.00E-05
7.00E-03
3.00E-01
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
mg/kg/day
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
skin
kidney
none
digestive system
body weight
liver
liver
liver
liver
ND
CNS/Blood
eye
CNS/Body Weight
CNS
CNS
skin
kidney
GI
CNS
kidney
body weight
blood
ND
blood
3
10
900
1000
3000
1000
1000
ND
1000
ND
3000
1000
1000
ND
100
3
10
ND
3
30
300
3000
100
3
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS
NCEA
IRIS
IRIS
IRIS
HEAST
NCEA
IRIS
IRIS
HEAST
IRIS
HEAST
IRIS
IRIS
HEAST
IRIS
08/24/00
08/24/00
08/24/00
08/24/00
08/24/00
08/24/00
08/24/00
07/97
08/24/00
4/13/2000
08/24/00
08/24/00
08/24/00
11/93
4/13/2000
08/24/00
08/24/00
07/97
08/24/00
07/97
08/24/00
08/24/00
07/97
08/24/00
Notes:
1 - Toxicity data presented in this table was not obtained from the BRA Reports; however, this information is provided in order to present all current available toxicological data for site-related COCs.
- COCs from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
3 - COCs from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
4 - References Doses used for the following: hexavalent chromium used for total chromium; thallium sulfate used for thallium.
5 - Represents Uncertainty Factor x Modifying Factor.
6 - For IRIS values, the date IRIS was searched.
For HEAST values, the date of HEAST.
For NCEA values, the date of EPA Region III Risk-Based Concentration Table.
GI - Gastrointestinal; CNS - central nervous system.
NA - Not applicable (noncarcinogenic COCs were not identified for the dermal exposure pathway).
ND - No chemical-specific available data.
/: \work\projects\75279\wordproc\FinalROD\Table7b rev01.xls
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Table 8
Additional Non-Cancer Toxicity Data - Inhalation
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Chemical of Concern
Chronic/
Subchronic
Inhalation
RfC
Units
Inhalation
RfD
Primary
Target
Organ
Combined
Uncertainty /Modifying
Factors
Sources of
RfC:RfD:
Target Organ
Dates of RfC:
Target Organ
(MM/DD/YY)
MAY 1990 BRA 2
No COCs
APRIL 1993 BRA 3
VOCs
Bromomethane
Butanone, 2-
Carbon tetraohloride
Chlorobenzene
Dichloroethene, 1,2-
Tetrachloroethene
Iriohloroethene
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
Chronic
5.00E-03
l.OOE+00
2.00E-03
5.95E-02
ND
4.90E-01
ND
mg/m3
mg/m3
mg/m3
mg/m3
ND
mg/m3
ND
1.43E-03
2.86E-01
5.71E-04
1.70E-02
ND
1.40E-01
ND
mg/kg-day
mg/kg-day
mg/kg-day
mg/kg-day
ND
mg/kg-day
ND
nasal
body weight
ND
ND
ND
ND
ND
100
3000
ND
ND
ND
ND
ND
IRIS
IRIS
NCEA
NCEA
ND
NCEA
ND
8/24/00
8/24/00
4/13/00
4/13/00
ND
4/13/00
ND
Notes:
1 - Toxicity data presented in this table was not obtained from the BRA Reports; however, this information is provided in order to present all current available toxicological data for site-related COCs
- COCs from Risk Assessment, Zone 1 Remedial Investigation Report, Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, May 1990).
3 - COCs from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993).
4 - Represents Uncertainty Factor x Modifying Factor.
5 - For IRIS values, the date IRIS was searched.
For NCEA values, the date of EPA Region III Risk-Based Concentration Table.
- Not applicable (no noncarcinogenic COCs identified for inhalation exposure pathway in May 1993 BRA).
ND - No chemical-specific data available.
l:\work\projects\75279\wordproc\FinalROD\Table8rev01.xls
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Table 9
Risk Characterization Summary - Carcinogens and Non Carcinogens1
Future On-Site Adult Resident - Groundwater
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Scenario Timeframe: Future
Receptor Population: Resident (On-Site)
Receptor Age: Adult
Medium
Groundwater -
Quaternary Alluvial Aquifer
and Unconfined Upper
Providence Unit
Exposure
Medium
Groundwater
Exposure
Point
Groundwater
Tap Water and
Water Vapors
Groundwater
Monitoring Well
LF4-6
LF4-4
RI1-6W
RI1-2W
LF4-27
LF4-WP9
LF4-25
LF4-WP7
LF4-9
LF4-WP8
LF4-WP1 1
LF4-23
LF4-WP5
LF4-WP10
LF4-30
LF4-PR4
RI1-7W
LF4-21
LF4-12
LF4-13
LF4-PR3
LF4-17
RI1-4W
LF4-WP12
LF4-15
LF4-32ES
LF4-18
LF4-WP3
LF4-16
Carcinogenic Risk
Ingestion
2.E-02
8.E-02
4.E-04
2.E-04
2.E-04
2.E-04
3.E-04
8.E-05
7.E-05
2.E-04
4.E-05
l.E-04
2.E-04
4.E-05
2.E-05
3.E-04
4.E-05
9.E-04
l.E-04
6.E-05
3.E-04
3.E-06
6.E-05
2.E-05
2.E-05
l.E-04
2.E-05
6.E-06
5.E-07
Inhalation
5.E-02
2.E-01
8.E-04
5.E-04
4.E-04
4.E-04
6.E-04
2.E-04
l.E-04
2.E-04
8.E-05
2.E-04
3.E-05
7.E-05
4.E-05
7.E-06
6.E-05
2.E-03
3.E-05
7.E-05
4.E-06
6.E-06
4.E-05
2.E-05
2.E-05
2.E-06
l.E-05
l.E-05
l.E-06
Dermal
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Total Risk Across Groundwater
Total Risk Across All Media and All Exposure Routes
Exposure
Routes Total
7.E-02
3.E-01
l.E-03
7.E-04
6.E-04
6.E-04
9.E-04
3.E-04
2.E-04
4.E-04
l.E-04
3.E-04
2.E-04
l.E-04
6.E-05
3.E-04
l.E-04
3.E-03
l.E-04
l.E-04
3.E-04
9.E-06
l.E-04
4.E-05
4.E-05
l.E-04
3.E-05
2.E-05
2.E-06
NC
NC
Non-Carcinogenic Hazard Quotient
Primary
Target Organ
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
NA
NA
NA
NA
Ingestion
145.34
13.23
11.13
6.76
5.66
4.87
4.68
2.52
2.03
2.62
2.24
1.58
1.55
1.49
2.35
2.50
0.93
1.19
1.32
1.38
1.90
1.32
0.46
0.55
1.13
NA
NA
NA
NA
Inhalation
283.92
24.68
20.99
13.27
11.07
9.35
7.93
4.72
3.65
3.04
2.48
2.88
1.76
2.18
1.29
0.44
1.59
1.13
0.93
0.86
0.10
0.07
0.76
0.58
NA
NA
NA
NA
NA
Dermal
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Total Hazard Index Across Groundwater
Total Hazard Index Across All Media and All Exposure Routes
Exposure
Routes Total
429.26
37.91
32.12
20.03
16.73
14.22
12.61
7.24
5.68
5.66
4.72
4.46
3.31
3.67
3.64
2.94
2.52
2.32
2.25
2.24
2.00
1.39
1.22
1.13
1.13
NA
NA
NA
NA
NC
NC
Page 1 of 2
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Table 9
Risk Characterization Summary - Carcinogens and Non Carcinogens1
Future On-Site Adult Resident - Groundwater
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Medium
Groundwater -
Confined Upper
Providence Unit
Groundwater -
Lower Providence
Unit
Groundwater -
Blufftown and
Cusseta Aquifer
Scenario Timeframe: Future
Receptor Population: Resident (On-Site)
Receptor Age: Adult
Exposure
Medium
Groundwater
Groundwater
Groundwater
Exposure
Point
Groundwater
Tap Water and
Water Vapors
Groundwater
Tap Water and
Water Vapors
Groundwater
Tap Water and
Water Vapors
Groundwater
Monitoring Well
LF4-42
LF4-38
LF4-11
LF4-40
LF4-8
LF4-3
RI1-5W
LF4-5
LF4-32
LF4-PR1
LF4-7
LF4-45
LF4-PR2
RI1-1W
LF4-39
LF4-43
LF4-34ES
LF4-35
LF4-33
RI1-3W
LF4-10
LF4-BL3
LF4-BL2
LF4-BL1
LF4-BL5
LF4-BL6
LF4-BL4
LF4-36ES
Carcinogenic Risk
Ingestion
.
5.E-05
3.E-06
3.E-06
3.E-06
6.E-06
3.E-06
l.E-05
l.E-05
2.E-05
NA
NA
3.E-05
2.E-05
7.E-06
4.E-05
l.E-05
3.E-05
l.E-05
3.E-05
2.E-05
7.E-05
2.E-05
3.E-04
2.E-04
l.E-05
6.E-05
5.E-05
Inhalation
5.E-06
8.E-07
5.E-06
7.E-06
6.E-06
l.E-06
6.E-06
NA
2.E-05
NA
NA
NA
NA
3.E-06
NA
NA
NA
NA
2.E-05
5.E-07
NA
NA
NA
NA
NA
NA
NA
NA
Dermal
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Total Risk Across Groundwater
Total Risk Across All Media and All Exposure Routes
Exposure
Routes Total
5.E-06
5.E-05
8.E-06
l.E-05
9.E-06
7.E-06
9.E-06
l.E-05
3.E-05
2.E-05
ND
ND
3.E-05
2.E-05
7.E-06
4.E-05
l.E-05
3.E-05
3.E-05
3.E-05
2.E-05
7.E-05
2.E-05
3.E-04
2.E-04
l.E-05
6.E-05
5.E-05
NC
NC
Non-Carcinogenic Hazard Quotient
Primary
Target Organ
ND
NA
NA
NA
NA
NA
NA
NA
NA
ND
ND
ND
NA
NA
NA
NA
NA
NA
NA
NA
NA
ND
ND
ND
ND
ND
ND
ND
Ingestion
0.42
NA
NA
NA
NA
NA
NA
NA
NA
2.51
0.92
1.15
NA
NA
NA
NA
NA
NA
NA
NA
NA
11.81
2.04
1.41
NA
NA
NA
NA
Inhalation
0.94
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.42
0.001
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Dermal
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Total Hazard Index Across Groundwater
Total Hazard Index Across All Media and All Exposure Routes
Exposure
Routes Total
1.36
NA
NA
NA
NA
NA
NA
NA
NA
2.51
1.34
1.15
NA
NA
NA
NA
NA
NA
NA
NA
NA
11.81
2.04
1.41
NA
NA
NA
NA
NC
NC
Notes:
1 -Data from Draft Final Remedial Investigation Report for Zone 1, Operable Unit 3: Robins Air Force Base, Warner Robins, Georgia (CH2M Hill, April 1993);
all calculations of risks and hazards are based upon sample-specific information and includes all COPCs (not COCs only).
NA- Not Applicable (note: potential risks and hazards via dermal pathway were not calculated, as pathway was considered insignificant; others as noted).
NC - total risks and hazards not calculated in the BRA Report (estimates were only presented on a per-well basis).
ND - no data documented in BRA Report.
Exposure Assumptions:
Exposure (mg/kg body weight/day) = (C x IR x EF x ED) / (BW x AT); where:
C = RME concentration of chemical in groundwater well
[R (tap water) = 2 liters/day for ingestion
[R (water vapors) = 4 liters/day (equivalent mass) for inhalation of VOCs
BW = 70 kilograms for body weight
EF = 350 days/year for exposure frequency
ED = 30 years for exposure duration
AT (carcinogens) = averaging time (70 years x 365 days/year for carcinogens)
AT (noncarcinogens) = averaging time (ED years x 365 days/year for nonearcinogens)
-------
Table 10
Summary of Final Chemicals of Concern in Groundwater
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Scenario Timeframe: Future
VIedium: Groundwater
Exposure Medium: Groundwater
Exposure Point
Surficial Aquifer
Quaternary Alluvial Aquifer
Upper Providence Unit
Chemical of Concern
VOCs
Benzene
Chlorobenzene
Dichloroethene, cis-1,2-
Cis-l,2-dichloroethene
Tetrachloroethene
Trichloroethene
Metals
Arsenic
Cadmium
Chromium
Lead
VOCs
Carbon tetrachloride
Chlorobenzene
Tetrachloroethene
Trichloroethene
Vinyl chloride
VOCs
Carbon tetrachloride
Tetrachloroethene
Trichloroethene
Concentration Detected
Minimum
6.70E-01
1.80E+00
6.00E-01
1.10E+00
2.40E+00
3.00E+00
3.00E-01
5.00E-01
1.30E+00
5.00E-01
7.40E-01
6.20E-01
5.30E-01
3.10E+00
5.00E-01
6.20E-01
5.30E-01
Maximum
l.OOE+02
4.50E+02
1.30E+03
5.40E+01
5.90E+02
3.94E+02
4.53E+01
5.73E+01
1.13E+02
3.80E+01
8.50E+02
1.50E+02
8.40E+02
1.70E+02
3.80E+01
1.50E+02
8.40E+02
Mean
8.19E+00
2.85E+01
2.79E+01
7.71E+00
3.76E+01
3.44E+01
3.69E+00
5.35E+00
1.21E+01
4.36E+00
2.51E+01
9.64E+00
2.11E+01
2.30E+01
4.36E+00
9.64E+00
2.11E+01
Units
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Hg/L
Frequency of
Detection
25/33
26/33
11/33
7/33
12/33
21/33
26/33
29/33
25/33
21/36
7/36
23/36
32/36
3/36
21/36
23/36
32/36
Exposure Point
Concentration 4
l.OOE+02
4.50E+02
1.30E+03
5.40E+01
5.90E+02
3.94E+02
4.53E+01
5.73E+01
1.13E+02
3.80E+01
8.50E+02
1.50E+02
8.40E+02
1.70E+02
3.80E+01
1.50E+02
8.40E+02
Exposure Point
Concentration
Units
Hg/L
Mg/L
Mg/L
Hg/L
Hg/L
Hg/L
Mg/L
Mg/L
Hg/L
Hg/L
Hg/L
Hg/L
Mg/L
Mg/L
Hg/L
Hg/L
Hg/L
Statistical
Measure 4
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
MAX
Notes:
- Information presented in this table obtained from Draft Final Feasibility Study Report for Zone 1, Operable Units 1 and 3 (Volume 1), Robins Air Force Base, Warner Robins, Georgia (Earth Tech/RUST E & I, August 1999).
2 - Chemicals of Concern (COCs) are identified as those chemicals which exceed chemical-specific MCLs (Earth Tech/Rust E&I, 1999).
3 - Detected concentrations are reported in the FS based upon analytical groundwater data from the Spring 1998 Basewide Sampling (Rust E&I, 1998).
4 - Exposure point concentration is based upon the maximum detected concentration (MAX) detected in on-site monitoring wells.
fig/L - micrograms per liter
NA - not applicable
MAX - maximum detected concentration
MCLs - maximum contaminant levels
VOCs - volatile organic compounds
l:\work'\projects\75279\wor
-------
Table 11
Comparative Analysis of Alternatives for OU3
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Criteria
OVERALL PROTECTIVENESS
Human Health Protection
Direct Contact/Soil Ingestion
Groundwater Ingestion for Current Users
Groundwater Ingestion for Potential Future
Users
Environmental Protection
COMPLIANCE WITH ARARs
Chemical-Specific ARARs
Location-Specific ARARs
Alternative 1
Baseline Conditions
Cap and stabilization has
reduced direct contact
risk and soil ingestion
risk to less than 1 x 1 0"5 .
There are no current
users of groundwater.
No reduction in risk.
Migration of COCs by
runoff and leaching is
eliminated by use of cap.
Allows continued
contamination of the
groundwater
Groundwater will always
exceed MCLs.
Would not meet location-
specific ARARs.
Alternative 2
Monitored Natural
Attenuation
Same as Alternative 1.
Same as Alternative 1.
COC levels in aquifer
estimated to achieve
MCLs by natural
attenuation in greater
than 50 years.
Migration of COCs by
runoff and leaching is
eliminated by use of
cap. Continued
migration of existing
contaminated
groundwater is allowed.
Would meet MCLs in
over 50 years.
Would not meet
location-specific
ARARs.
Alternative 3a
No Action - Continued
Operation of OUS
Interim Action
Same as Alternative 1 .
Same as Alternative 1 .
Plume migration controlled
by pumping. COC levels in
aquifer estimated to achieve
MCLs by natural attenuation
in less than 30 years.
Migration of COCs by
runoff and leaching is
eliminated by use of cap.
Migration of contaminated
groundwater is controlled by
pumping.
Would meet MCLs in less
than 30 years.
Would meet location-
specific ARARs
Alternative 3b(1)
Optimized OUS Interim
Action with Monitored
Natural Attenuation
Same as Alternative 1.
Same as Alternative 1.
Same as Alternative 3a
except optimized system
allows for greater removal
of groundwater
contamination.
Same as Alternative 3a
except optimized system
allows for greater removal
of groundwater
contamination.
Same as Alternative 3a.
Same as Alternative 3a.
Alternative 5a
Hot Spot Removal &
Alternative 4 Continued Operation of
Hot Spot Removal OUS Interim Action
Same as Alternative 1. Same as Alternative 1.
Same as Alternative 1. Same as Alternative 1.
COC levels in aquifer Same as Alternative 3a.
estimated to achieve MCLs
by hot spot removal in
greater than 40 years.
Groundwater not likely to
be useable since
remediation not likely to be
successful.
Migration of COCs by Same as Alternative 3a.
runoff and leaching is
eliminated by use of cap.
Migration of contaminated
groundwater is controlled
by hot spot removal.
Would meet MCLs in Same as Alternative 3a.
greater than 40 years.
Would not meet location- Same as Alternative 3a.
specific ARARs.
Alternative 5b
Hot Spot Removal &
Optimized Operation of
OUS Interim Action
Same as Alternative 1 .
Same as Alternative 1 .
Same as Alternative 3a
except optimized system
allows for greater removal of
groundwater contamination.
Same as Alternative 3a
except optimized system
allows for greater removal of
groundwater contamination.
Same as Alternative 3a.
Same as Alternative 3a.
Alternative 6
Complete Extraction ol
Impacted Groundwater
Same as Alternative 1 .
Same as Alternative 1 .
Same as Alternative 3a
but the most protective
since groundwater
contamination is
completely removed.
Same as Alternative 3a
but the most protective
since groundwater
contamination is
completely removed.
Same as Alternative 3a.
Same as Alternative 3a.
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Table 11
Comparative Analysis of Alternatives for OU3
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Criteria
Action-Specific ARARs
Other Criteria and Guidance
Alternative 1
Baseline Conditions
Meets RCRA minimum
technology requirements
for caps. No other
action-specific ARARs
Would allow ingestion
of groundwater
exceeding MCLs for
future users.
Alternative 2
Monitored Natural
Attenuation
Same as Alternative 1.
Would allow ingestion
of groundwater
exceeding MCLs for
future users.
Alternative 3a
No Action - Continued
Operation of OUS
Interim Action
Meets RCRA minimum
technology requirements for
caps. Action-specific
ARARs associated with
Alternative 3a were
managed as part of the OUS
Interim Action. No
additional action-specific
ARARs are required for this
alternative.
More likely to meet ARARs.
Alternative 3b(1)
Optimized OUS Interim
Action with Monitored
Natural Attenuation
Same as Alternative 3a.
More likely to meet
ARARs than Alternative
3a.
Alternative 4
Hot Spot Removal
Meets RCRA minimum
technology requirements for
caps. Action-specific
ARARs include
construction permits for
extraction wells and control
of air emissions from
groundwater treatment
units.
Due to potential failure of
remediation system,
ARARs not likely to ever
be met.
Alternative 5a
Hot Spot Removal &
Continued Operation of
OUS Interim Action
Same as Alternative 4.
More likely to meet ARARs
than Alternative 3a.
Alternative 5b
Hot Spot Removal &
Optimized Operation of
OUS Interim Action
Same as Alternative 4.
More likely to meet ARARs
than Alternative 3a.
Alternative 6
Complete Extraction ol
Impacted Groundwater
Same as Alternative 4
plus NPDES
requirements from
increased flow rate to
groundwater treatment
plant.
Most likely to meet
ARARs than all
alternatives.
LONG TERM EFFECTIVENESS AND PERMANENCE
Magnitude of Residual Risk
Direct Contact/Soil Ingestion
Groundwater Ingestion for Current Users
Groundwater Ingestion for Potential Future
Users
Adequacy and Reliability of Controls
Risk from OU1 source
materials is contained.
There are no current
users of groundwater.
High risk remains for
future users.
No controls over
remaining
contamination. No
reliability.
Contaminants would
remain on-site above
health-based levels.
Same as Alternative 1.
Same as Alternative 1.
Ability for complete
clean-up of groundwater
by natural attenuation is
not likely.
Low reliability for
natural attenuation
alone.
Contaminants would
remain on-site above
health-based levels.
Same as Alternative 1 .
Same as Alternative 1 .
Eventual clean-up of
groundwater likely but use
of some groundwater from
the Surficial Aquifer may be
limited due to residual
metals contamination.
Reliability of existing
groundwater pump and treat
system is high.
Same as Alternative 1.
Same as Alternative 1.
Residual risk less than 3a
due to optimized removal
system .
Reliability of optimized
groundwater pump and
treat system would be high.
Same as Alternative 1.
Same as Alternative 1.
Residual risk greater than
all other alternatives except
land 2.
Hot spot removal alone is
not reliable based on past
experience at site.
Hot spot removal could
compromise the integrity of
the cap.
Same as Alternative 1.
Same as Alternative 1.
Residual risk less than 3a
due to addition of hot spot
removal .
Same as Alternative 4.
Same as Alternative 1 .
Same as Alternative 1 .
Residual risk less than 3b
due to addition of hot spot
removal .
Same as Alternative 4.
Same as Alternative 1 .
Same as Alternative 1 .
Best alternative for
residual risk.
High reliability for
complete groundwater
pump and treat system.
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Table 11
Comparative Analysis of Alternatives for OU3
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Criteria
Alternative 1
Baseline Conditions
Alternative 2
Monitored Natural
Attenuation
Alternative 3a
No Action - Continued
Operation of OUS
Interim Action
Alternative 3b(1)
Optimized OUS Interim
Action with Monitored
Natural Attenuation
Alternative 4
Hot Spot Removal
Alternative 5a
Hot Spot Removal &
Continued Operation of
OUS Interim Action
Alternative 5b
Hot Spot Removal &
Optimized Operation of
OUS Interim Action
Alternative 6
Complete Extraction ol
Impacted Groundwater
REDUCTION OF TOXICIT Y, MOBILITY, OR VOLUME THROUGH TREATMENT
Treatment Process Used
Amount Destroyed or Treated
Reduction of Toxicity, Mobility, or
Volume
Irreversible Treatment
Type and Quantity of Residuals
Remaining After Treatment
SHORT-TERM EFFECTIVENESS
Community Protection
Worker Protection
None.
None.
None.
None.
Groundwater
contamination remains.
Risk to community
through recreational
users of downgradient
wetlands remains due to
no action.
No risk to workers.
None.
None.
Some reduction of
toxicity but no volume.
None.
Groundwater
contamination remains.
Risk to community
through recreational
users of downgradient
wetlands is likely with
this alternative.
Negligible risk occurs
during sampling for
natural attenuation.
Groundwater pump and treat
by ozonation and carbon
adsorption.
Estimated 95% of volatiles
in groundwater removed and
destroyed by ozonation and
carbon absorption.
Reduced volume and
toxiciry of contaminated
groundwater.
Yes, unless residual
contamination leaches to
groundwater after treatment.
Small quantity of immobile
metals may remain.
Risk to community minimal
Negligible risk to workers
during inspections of
groundwater extraction
system and during sampling.
Groundwater pump and
treat by ozonation and
carbon adsorption.
Estimated 99% of volatiles
in groundwater removed
and destroyed by ozonation
and carbon absorption.
Greater reduced volume
and toxicity of
contaminated groundwater
than alternative 3a.
Same as Alternative 3a.
Same as Alternative 3a
Same as Alternative 3a.
Same as Alternative 3a.
Air sparging with soil vapor
extraction.
Estimated 80% of volatiles
in groundwater removed by
air sparging.
Some reduction of toxicity
but no volume.
Same as Alternative 3a.
Groundwater contamination
likely remains.
Same as Alternative 3a.
Greater risk to workers
since cap will be breeched
to install air sparge wells.
Air sparging with soil vapor
extraction. Groundwater
pump and treat by ozonation
and carbon adsorption.
Estimated 99% of volatiles
in groundwater removed and
destroyed by air sparging,
ozonation, and carbon
absorption.
Reduced volume and
toxicity of contaminated
groundwater.
Same as Alternative 3a.
Same as Alternative 3a
Same as Alternative 3a.
Same as Alternative 4.
Air sparging with soil vapor
extraction. Groundwater
pump and treat by ozonation
and carbon adsorption.
Estimated 99+% of volatiles
in groundwater removed and
destroyed by air sparging,
ozonation, and carbon
absorption.
Greater reduced volume and
toxiciry of contaminated
groundwater than all
alternatives except
alternative 6.
Same as Alternative 3a.
Same as Alternative 3a
Same as Alternative 3a.
Same as Alternative 4.
Groundwater pump and
treat by ozonation and
carbon adsorption.
Estimated 100% of
volatiles in groundwater
removed and destroyed
by ozonation and carbon
absorption.
Complete reduction of
volume and toxicity.
Same as Alternative 3a.
Same as Alternative 3a
Same as Alternative 3a.
Greater risk to workers
since cap will be
breeched to install
additional extraction
wells.
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Table 11
Comparative Analysis of Alternatives for OU3
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Criteria
Environmental Impacts
Time Until Action Is Complete
[MPLEMENTABILITY
Ability to Construct and Operate
Ease of Doing More Action If Needed
Ability to Monitor Effectiveness
Ability to Obtain Approvals and
Coordinate With Other Agencies.
Availability of Equipment, Specialists,
and Materials
Availability of Technologies
Alternative 1
Baseline Conditions
Continued impacts from
existing conditions.
Not applicable.
No construction or
operation.
May require ROD
amendment if future
problems arise.
No monitoring.
None required.
None required.
None required.
Alternative 2
Monitored Natural
Attenuation
Some migration of
contaminant plume as
part of attenuation
process.
Immediate
implementation.
No construction or
operation.
May require ROD
amendment if future
problems arise.
Monitoring and
maintenance inspections
included with
alternative.
Same as Alternative 1 .
None required.
None required.
Alternative 3a
No Action - Continued
Operation of OUS
Interim Action
Some migration of
contaminant plume to
wetlands area.
Immediate implementation.
Already constructed.
Easy to increase flow rate.
Difficult if additional
extraction wells are needed.
Same as Alternative 2.
Same as Alternative 1 .
None required.
None required.
Alternative 3b(1)
Optimized OUS Interim
Action with Monitored
Natural Attenuation
Same as Alternative 3 a.
Design and
implementation of
optimized interim action
would take 6 months,
Already constructed.
Same as Alternative 3a.
Same as Alternative 2.
Minor approvals required.
Personnel readily available
to provide groundwater
modeling to determine
optimized system
parameters.
Specialized for this site.
Alternative 4
Hot Spot Removal
Considerable migration of
contaminant plume to
wetlands area. Air impacts
from vapor extraction.
Design and installation of
AS/SVE system would take
18 months.
Difficult to construct and
time consuming to operate.
Difficult to add additional
sparge/SVE points.
Same as Alternative 2.
Significant approvals
required due to intrusion
into cap and air permitting
issues.
Extensive equipment and
specialists required due to
intrusion into cap may not
be readily available.
Readily available.
Alternative 5a
Hot Spot Removal &
Continued Operation of
OUS Interim Action
Some migration of
contaminant plume to
wetlands area. Air impacts
from vapor extraction.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 2.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 4
Alternative 5b
Hot Spot Removal &
Optimized Operation of
OUS Interim Action
Same as Alternative 5a.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 2.
Same as Alternative 4.
Same as Alternative 4.
Same as Alternative 4
Alternative 6
Complete Extraction ol
Impacted Groundwater
Lowest impact to
environment of all
alternatives.
Design and
implementation of scaled
up groundwater treatmem
plant would be 30
months.
Same as Alternative 4.
Difficult to add
additional extraction
wells.
Same as Alternative 2.
More extensive approvals
required due to intrusion
into cap. Revision of
NPDES permit.
Same as Alternative 4.
Specialized for this site.
L:/work/projects/? 5279/worc^i-oc/Fifial ROB\TableU revOJ.xls
Page 4 of 5
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Table 11
Comparative Analysis of Alternatives for OU3
Record of Decision for the NFL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Criteria
COST
Capital Cost
Annual O&M Cost
Present Worth Cost
STATE ACCEPTANCE
COMMUNITY ACCEPTANCE
Alternative 1
Baseline Conditions
$0
$0
$76,000
Not acceptable. Not
protective of human
health and environment.
Not acceptable.
Alternative 2
Monitored Natural
Attenuation
$0
$65,000
$882,000
Not acceptable. Not a
permanent solution.
Not acceptable.
Alternative 3a
No Action - Continued
Operation of OUS
Interim Action
$1,000,000
$1,000,000
$11,587,000
Acceptable.
Acceptable.
Alternative 3b(1)
Optimized OUS Interim
Action with Monitored
Natural Attenuation
$500,000
$932,000
$12,059,000a)
Acceptable.
Acceptable.
Alternative 4
Hot Spot Removal
$1,800,000
$124,000
$3,562,000
Not acceptable due to
intrusion into cap.
Not acceptable.
Alternative 5a
Hot Spot Removal &
Continued Operation of
OUS Interim Action
$2,800,000
$1,200,000
$17,914,000
Same as Alternative 4.
Not acceptable.
Alternative 5b
Hot Spot Removal &
Optimized Operation of
OUS Interim Action
$2,800,000
$1,200,000
$17,914,000
Same as Alternative 4.
Not acceptable.
Alternative 6
Complete Extraction ol
Impacted Groundwater
$10,000,000
$3,000,000
$47,450,000
Not acceptable
Not acceptable
^ - These costs are based upon the 30 year scenario. Actual time frames and cost are dependent upon the evaluation of the groundwater extraction system effectiveness.
- US EPA guidance specifies that costs are to be presented in terms of present worth. However, it should be noted that a different economic analysis including escalated costs was presented in the FS (Earth Tech/RUST E&I, 1999a).
Therefore, the cost estimates presented here and in the FS are not comparable.
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Page 5 of 5
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Table 12
Cost Estimate Summary for the OU3 Selected Final Remedy
(10 year and 30 year Scenarios)
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Description
Capital Costs (for 10 year and 30 year periods (P))
1 . Remedial Design/Groundwater Optimization Study
Contingency Allowances (15%)
Project Management and Support (10%)
Annual Operation & Maintenance (P = 10 years)
Groundwater Monitoring
Operation of Groundwater Treatment Plant '
CERCLA Five Year Review
Contingency Allowances (25%)
Project Management Support (15%)
Equivalent Uniform Annual O&M Cost (P = 10 yrs)
Net Present Worth of Capital Costs and O&M Costs (I = 7%, P = 10 yrs)
Annual Operation & Maintenance (P = 30 years)
Groundwater Monitoring
Operation of Groundwater Treatment Plant (1)
CERCLA Five Year Review
Contingency Allowances (25%)
Project Management Support (15%)
Equivalent Uniform Annual O&M Cost (P = 30 yrs)
Net Present Worth of Capital Costs and O&M Costs (I = 7%, P = 30 yrs)
Quantity Unit Unit Cost Cost
1 LS $400,000 $400,000
Subtotal $400,000
$60,000
$40,000
Total Capital Costs: $500,000
10 per year $239,000 $2,390,000
10 per year $433,000 $4,330,000
2 review periods $90,000 $180,000
Subtotal $6,900,000
$1,725,000
$690,000
Total O&M Costs: $9,315,000
$931,500
| $7,041,925
30 peryear $239,000 $7,170,000
30 peryear $433,000 $12,990,000
6 review periods $90,000 $540,000
Subtotal $20,700,000
$5,175,000
$2,070,000
Total O&M Costs: $27,945,000
$931,500
| $12,058,984 '
I
I
Notes:
LS = Lump Sum
= Annual costs associated with treatment of up to 50 gpm of groundwater through the groundwater treatment plant.
1. These costs are based upon 10 year and 30 year scenarios; actual time frames and cost are dependent up the evaluation of the groundwater extraction system effectiveness.
2. US EPA guidance specifies that costs are to be presented in terms of present worth. However, it should be noted that a different economic analysis including escalated costs was
presented in the FS (Earth Tech/RUST E&I, 1999a). Therefore, the cost estimates presented here and in the FS are not comparable.
Page I of 2
-------
Table 12
Cost Estimate Summary for the OU3 Selected Final Remedy
(10 year and 30 year Scenarios)
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Summary of Present Worth Analysis
Year Capital Cost Annual O&M Cost Total Cost Discount Factor (7%)
Present Worth
(P = 10 years)
Present Worth
(P = 30 years)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
$500,000
$500,000
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$27,945,000
TOTAL PRESENT WORTH COSTS
$500,000
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$931,500
$28,445,000
1.000
0.935
0.873
0.816
0.763
0.713
0.666
0.623
0.582
0.544
0.508
0.475
0.444
0.415
0.388
0.362
0.339
0.317
0.296
0.277
0.258
0.242
0.226
0.211
0.197
0.184
0.172
0.161
0.150
0.141
0.131
$500,000
$870,953
$813,200
$760,104
$710,735
$664,160
$620,379
$580,325
$542,133
$506,736
$473,202
$7,041,925
$7,041,925
$500,000
$870,953
$813,200
$760,104
$710,735
$664,160
$620,379
$580,325
$542,133
$506,736
$473,202
$442,463
$413,586
$386,573
$361,422
$337,203
$315,779
$295,286
$275,724
$258,026
$240,327
$225,423
$210,519
$196,547
$183,506
$171,396
$160,218
$149,972
$139,725
$131,342
$122,027
$12,058,984
$12,058,984
Notes: Capital cost estimates are not discounted because the construction work will be performed in the first year. O&M costs are reported as
present worth estimates given a 7% discount rate for both a 10 year and a 30 year duration. Costs estimates are within +50 to -30% accuracy
expectation. Project management and support should account for the cost of remedial design and the administrative/project management costs for the
remedial design/remedial action and O&M.
L:/work/projects/75279/WordProc/Final RODfTablel2 rev01.xls
sm
Page 2 of2
10/14/2004
-------
Table 13
Decision Matrix for Comparison of Alternatives
Record of Decision for the NPL Site, Operable Units (OTJs) 1 and 3
Robins AFB, Georgia
Criterion
Remedial Alternatives
Alternative I
Alternative 2
Alternative 3a
Alternative 3b
Alternative 4
Alternative 5a
Alternative 5b
Alternative 6
Overall Protectiveness
Human Health
Environment
Compliance with ARARs
Chemical
Location
Action
X
X
X
X
X
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Long-Term Effectiveness and Permanence
Magnitude of residual
risks
Adequacy of controls
X
X
*
«/
*
*
*
*
*
«/
*
*
*
*
*
*
Reduction in Toxicity, Mobility, or Volume Through Treatment
Reduction
X
*
*
*
*
*
*
*
Short-Term Effectiveness
Risk to community or
workers
Time frame to achieve
MCLs
Implementability
Ease of Implementation
Costs
Total escalated costs (1)
*
X
*
$200,000
«/
*
*
$4,200,000
*
*
*
$67,000,000
*
*
*
$46,000,000
*
*
*
$8,900,000
*
*
*
$88,000,000
*
*
*
$63,000,000
*
^
*
$104,000,000
Notes:
(1) Economic Analysis included escalated costs as presented in the Feasibility Study (Earth Tech/RUST E&I, 1999a).
* Meets Criteria
X Does Not Meet Criteria
* Has Concerns, May or May Not Meet Criteria
l:\worK\projects\75279\wordproc\FinalROD\Tables 10J3J4 rev01.xls
sm
10/14/2004
-------
Table 14
Description of ARARs for Selected Remedy
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Authority
Medium
Requirement
Status
Synopsis of Requirement
Action to be Taken to Attain
Requirement
State
Regulatory
Requirement
Soil
Federal
Regulatory
Requirement
Groundwater
Federal
Regulatory
Requirement
Groundwater
Federal
Regulatory
Requirement
Federal
Regulatory
Requirement
Surface Water
Wetland
State Hazardous Applicable
Waste Management
Rules
Federal Safe
Drinking Water
Maximum
Contaminant Levels
(MCLs)
Relevant and
Appropriate
RCRA disposal
requirements
(40CFR264)and
land disposal
restrictions
(40 CFR 268) for
groundwater-
treatment residuals
Clean Water Act
(40 CFR 122)
Relevant and
Appropriate
Relevant and
Appropriate
Protection of
Wetlands, Executive
Order 11990
(40 CFR Part 6)
TBC
These rules set forth the State's
definitions and criteria for
establishing whether waste
materials are hazardous and
subject to associated hazardous
waste regulations. These rules
identify requirements for
hazardous waste generators and
land disposal restrictions.
MCLs have been regulated for a
number of common organic and
inorganic contaminants. These
levels regulate the concentrations
of contaminants in public
drinking water supplies and are
considered relevant and
appropriate for groundwater
aquifers potentially used for
drinking water.
RCRA disposal requirements
have been developed to protect
human health and the
environment.
Standards have been developed to
protect human health and the
environment from direct
discharge of treatment effluent.
These requirements regulate
actions that occur in wetlands and
may be applicable to actions that
may adversely affect wetlands.
The Selected Remedy will
comply with these requirements
through containment via capping
of the landfill.
The Selected Remedy will
comply with these regulations
through source control measures
and monitored natural
attenuation. The exception to
this are residual metals
remaining in the Surficial
Aquifer of the waste mass which
would be regulated under the
RCRA land disposal regulations,
40 CFR 264 and 40 CFR 268
(see below).
The Selected Remedy will
comply with these regulations
through source control measures.
The Selected Remedy will
comply with these regulations
through proper treatment of
contaminated groundwater
extracted from the NPL site.
The Selected Remedy will
indirectly help to protect the
wetlands.
Note:
TBC = To Be Considered
/: \\vork\projects\75279\wordproc\FinalROD\Tables 10J3J4 revOLxls
10/14/2004
-------
ATLANTA
*
ROBINS
AIR FORCE
BASE
RESERVATION BOUNDARY
NOT TO SCALE
WP14
LUDGE
LAGOON
(NPL SITE)
SCOUT
LAKE
LF04
(NPL SITE)
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH, 2003)
ROBINS AIR FORCE BASE, GEORGIA
SCALE
FIGURE 1
SITE LOCATION MAP
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279033.dgn
DATE; 19 Apr, 2004 TIME; 1054
SOURCE:
DRAFT FINAL REMEDIAL ACTION PLAN,
COVER RENOVATION OF LF04,
(ECC. 1997)
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 2
LANDFILL NO. 4 AND WP14 SLUDGE
LAGOON (NPL SITE) MAP
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
7 y^. Fikci
Cdll*«3r
I- iJt-i i . -HI
V.^SV.^AVAWA^.V.1^."
m-" -..:":-::,
.
«»«*«*»«
111 ilii EEII iiii Hit ilii 1
L ' jt" jit ' jt ' WJt ' A : y : A j !! ' 'i " A ' A * j
I a/fir « >:> *i.
Uy*r 5 18 in, Grading Soi
13 oe f
Cecr-=t Ca3 Callectc-
?<& rillrr
l G'.idingSoil
-------
^
,'
hjr Hn.iMify ^ >
T f*
'''
'
-'
»i*5
NOT TO SCALE
-------
..\75279036A.dgn
DATE; 19 Apr. 2004 TIME; 1056
qnilRPF
SOURCE
MEDIUM
RELEASE
MECHANISM
EXPOSURE
MEDIUM
EXPOSURE
ROUTE
RECEPTORS
HUMAN
CURRENT
INDUSTRIAL TRESPASSER / RES|DENT2
WORKER RECREATOR
FUTURE
RESIDENT
INDUSTRIAL
WORKER
ECOLOGICAL
CURRENT &
TERRESTRIAL
FUTURE
AQUATIC
LANDFILL N0.4
p
SOIL
LEGEND
1- INFORMATION FOR CSM BASED UPON POTENTIAL RECEPTORS AND
EXPOSURE PATHWAYS IDENTIFIED IN THE BRA ZONE 1, OU3
(CH2M HILL, MAY 1990 & APRIL 1993).
2- CURRENT RESIDENTIAL SCENARIO (OFF-SITE) EVALUATED FOR NEARBY
BASE HOUSING LOCATED SOUTH OF THE SITE.
3- ALL POTENTIAL EXPOSURES FOR OU1 ARE PRESENTLY CONSIDERED
INCOMPLETE ANDOR INSIGNIFICANT DUE TO COMPLETION OF INTERIM
ACTIONS.
4- OFF-SITE WETLAND RECEPTORS WERE ADDRESSED IN BRA FOR
OU2 WETLANDS STUDY AREA AND ARE NOT INCLUDED IN THIS ROD.
6- POTENTIAL GROUNDWATER EXPOSURES ARE PRESENTED FOR OU3 ONLY;
BASED ON HYPOTHETICAL FUTURE ON-SITE GROUNDWATER USE OF
UPPER AQUIFERS.
X- INDICATES POTENTIALLY COMPLETE EXPOSURE PATHWAY TO RECEPTOR.
EMPTY BOXES REPRESENT INCOMPLETE PATHWAYS.
LEACHING
DERMAL CONTACT
ROBINS AIR FORCE BASE, GEORGIA
X5
UUSI
GENERATION
UPTAKE BY
PLANTS
STORMWATER
RUNOFF
(OU3)
INFILTRATION/
AIM (uuai)
TERRESTRIAL
FOOD CHAIN
AQUATIC
FOOD CHAIN
SURFACE
WATER
I t
r^nni IMRVA/ATPR
IMHAI ATIHM
INGESTION
DERMAL CONTACT
IMriFQTinM
INGESTION
INGESTION
DERMAL CONTACT
INGESTION
DERMAL CONTACT
INGESTION
IMMAI ATICIM
A
X3
XJ
XJ
X4
X4
X4
X4
X4
A
X3
X4
X4
X4
X4
X4
X5
Y5
A
X3
X3
X3
X3
X4
X4
X4
X4
X4
SOURCE:
DRAFT FINAL REMEDIAL ACTION PLAN,
COVER RENOVATION OF LF04.
IECC. 19971- WITH EDITS
FIGURE 5
CONCEPTUAL SITE MODEL
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
£K
LJ
WEST * EAST
-1 a:
LJ LL.
§ 8 UPLAND AREAS
245' -305' ^ < , ' ^ K
(/)
VATION
LJ
LJ
LJ
s.
X
o
a:
9:
17^' - IQ*N'
130' -160'
1
2
4
100' -120'
5
LJ
O
LJ
Q
o
QL
Q.
QL
LJ
CL
CL
LJ
O
0£ Z
LJLJ
SQ
o>
I o
oc
Q.
i
(/)
(/)
0
z
0
1
LL.
CO
V SIJRFICIAI v
^^^\ AQUIFER <
\ ^
\ / ^ -1
""- vy ^~""S~~~"-*C - ri
^T-^^-.-VTT.r.-j^x. HORSE g o
LANDFILL >----^ CREEK ^ 2
\ V 7
\^ PEAT/CLAYVV
'^.
\VALLUVIAL GRAVEL
DISCONTINUOUS s~ -
CLAY LENSES ~~~ ~~~ ~~
^- /
AQUITARD
K2
z^
LJD
<=!
O
^
1
2
4
5
1%
ft VjK^ST \ SECTION
-------
...\75279039.dgn
DATE; 19 Apr, 2004 TIME; 1103
SLUDGE LAGOON
SURFICIAL WELL
LEACHATE WELL
(allvalues in uq/L)
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
ROBINS AIR FORCE BASE, GEORGIA
NOTES:
LF4PS1-LF4PS4 are the leachate
toe drain sumps for the OU3
Groundwoter Treatment System.
Data from wells labeled with italics
not used for contouring
0'
600'
SCALE
1200'
FIGURE 7
1998 TCE CONCENTRATIONS
SURFICIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279047.dgn
DATE; 19 Apr, 2004 TIME; 1106
=W.' ^^$\ C
F^=^ f^-^r\r l1^.
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
SURF 1C IAL WELL
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.J - ESTIMATED CONCENTRATION
o1
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 8
2003 TCE CONCENTRATIONS
SURFICIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279038.dgn
DATE; 19 Apr, 2004 TIME; 1102
LEGEND
BMDL - 10 ug/L
ROBINS AIR FORCE BASE, GEORGIA
10 - 100 ug/L
100 - 1,000 ug/L
1,000 - 10,000 ug/L
10,000 - 100,000 ug/L
0'
600'
SCALE
1200'
FIGURE 9
1989 TCE CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\7527904Q.dgn
DATE; 19 Apr, 2004 TIME; 1103
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
ALLUVIAL WELL
PEAT/CLAY WELL
I all values in ug/L)
TCE l>10)
Data from wells labeled with
italics not used for contouring
0'
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 10
1998 TCE CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279048.dgn
DATE; 19 Apr, 2004 TIME; 1106
^4-6
AM ^Vx
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
ROBINS AIR FORCE BASE, GEORGIA
A ALLUVIAL WELL
100 TCE CONTOUR IN ug/L
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.J - ESTIMATED CONCENTRATION
600'
SCALE
1200'
FIGURE 11
2003 TCE CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
2001
LEGEND
A ALLUVIAL WELL
® PEAT/CLAY WELL
-100 TCE CONTOUR IN ug/L
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.DATA FROM WELLS LABELED IN PARENTHESIS
WERE NOT USED FOR CONTOURING.
3.J - ESTIMATED CONCENTRATION
4.D - DILUTED SAMPLE
2002
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH, 2003)
2003
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 12
HISTORICAL TCE CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279041.dgn
DATE; 19 Apr, 2004 TIME; 1104
SLUDGE LAGOON
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
ROBINS AIR FORCE BASE,
LEGEND
® UPPER PROVIDENCE
(all values in ug/L)
TCE (10-1000)
TCE 01000)
WELL
0'
600'
SCALE
1200'
FIGURE 13
1998 TCE CONCENTRATIONS
UPPER PROVIDENCE
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279050.dgn
DATE; 19 Apr, 2004 TIME; 1107
5LUDGE LAGDDN
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
ROBINS AIR FORCE BASE, GEORGIA
LEGEND
UPPER PROVIDENCE WELL
TCE CONTOUR IN ug/L
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.DATA FROM WELLS LABELED IN PARENTHESIS
WERE NOT USED FOR CONTOURING.
3.J - ESTIMATED CONCENTRATION
0' 600' 1200'
SCALE
FIGURE 14
2003 TCE CONCENTRATIONS
UPPER PROVIDENCE
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
2000
2001
2002
© UPPER PROVIDENCE WELL
-100 TCE CONTOUR IN ug/L
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.DATA FROM WELLS LABELED IN PARENTHESIS
WERE NOT USED FOR CONTOURING.
3.J - ESTIMATED CONCENTRATION
4.D - DILUTED SAMPLE
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH, 2003)
2003
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 15
HISTORICAL TCE CONCENTRATIONS
UPPER PROVIDENCE
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279042.dgn
DATE; 19 Apr, 2004 TIME; 1104
El LOWER PROVIDENCE WELL
(all values in ug/L)
FIGURE 16
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
ROBINS AIR FORCE BASE, GEORGIA
1998 TCE CONCENTRATIONS
LOWER PROVIDENCE
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279051.dgn
DATE; 19 Apr, 2004 TIME; 1107
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
LOWER PROVIDENCE WELL
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.J - ESTIMATED CONCENTRATION
0'
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 17
2003 TCE CONCENTRATIONS
LOWER PROVIDENCE
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279044.dgn
DATE; 19 Apr, 2004 TIME; 1105
SLUDGE LAGOON
20 LF4-22
3.6 J
SURFICIAL WELL
LEACHATE WELL
[allvalues in ug/L)
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
ROBINS AIR FORCE BASE,
LEAD (TOTAL) 010)
NOTE:
LF4PS1-LF4PS4 are the leachate
toe drain sumps for the OU3
Groundwater Treatment System
0'
600'
SCALE
1200'
FIGURE 18
1998 LEAD CONCENTRATIONS
SURFICIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279053.dgn
DATE; 19 Apr, 2004 TIME; 1108
=W.' ^^$\ C
F^=^ f^-^r\r l1^.
SURF 1C IAL WELL
SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.J - ESTIMATED CONCENTRATION
F^EEZ
-53 rh D^:
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
0'
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 19
2003 LEAD CONCENTRATIONS
SURFICIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
.\75279043.dgn
DATE; 19 Apr, 2004 TIME; 1105
ROBINS AIR FORCE BASE, GEORGIA
LEGEND
BMDL - 10 ug/L
10 - 100 ug/L
>100 ug/L
0'
600'
SCALE
1200'
FIGURE 20
1989 LEAD CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279045.dgn
DATE; 19 Apr, 2004 TIME; 1106
SLUDGE LAGOON
RI10W3
< 1.1
RI10W4
9
LF4WP7
-272.2 J < 1.1
ALF4WP12
ALLUVIAL WELL
PEAT/CLAY WELL
(all values in ug/L)
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 1998 I RUST E & I, 1998)
NOTE:
Data from wells labeled with italics
not used for contouring
o1
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 21
1998 LEAD CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
...\75279054.dgn
DATE; 19 Apr, 2004 TIME; 1108
SOURCE:
BASEWIDE GROUNDWATER SAMPLING
REPORT SPRING 2003
(EARTHTECH. 2003)
ALLUVIAL WELL
- SURFACE WATER STREAMS
NOTES:
1.WELL VALUES IN ug/L
2.J - ESTIMATED CONCENTRATION
0'
600'
SCALE
1200'
ROBINS AIR FORCE BASE, GEORGIA
FIGURE 22
2003 LEAD CONCENTRATIONS
QUATERNARY ALLUVIAL AQUIFER
RECORD OF DECISION, NPL SITE, OU1 AND OU3
ROBINS AFB, GEORGIA
MARCH 2004 75279
-------
APPENDIX A
REVIEW OF INORGANIC CHEMICALS OF CONCERN
(NICKEL AND CHROMIUM)
Review of Inorganic Chemicals of Concern
Table A-l Historic Data for Chromium in Quaternary Alluvial Aquifer Monitoring locations for
OU3
Table A-2 Historic Data for Chromium in Quaternary Alluvial Aquifer Monitoring Locations for
OU3 Exceeding the MCL Historically
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Final
Appendix A -Review of Inorganic Chemicals of Concern (nickel and chromium)
Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
APPENDIX A
LIST OF ACRONYMS
ARAR Applicable or Relevant and Appropriate Requirements
COC Contaminants of Concern
MCL Maximum Concentration Level
NPL National Priorities List
OUS Operable Unit 3
(ig/L Micrograms per Liter
US EPA United States Environmental Protection Agency
L:\Work\Projects\75279\WordProc\FinalROD\FinalCOCAppendixA.doc A-i 9/13/2004
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Final
Appendix A -Review of Inorganic Chemicals of Concern (nickel and chromium)
Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
INTRODUCTION
As presented in the Feasibility Study Report (Rust E&I, 1999a) and the Draft Final Proposed Plan
(Rust E&I, 1999b) prepared for the National Priority List (NPL) site (Landfill number 4 and WP14
Sludge Lagoon), several inorganic parameters were identified as Chemicals of Concern (COCs) within
both the Surficial aquifer and the Quaternary alluvial aquifer. A total of five inorganic parameters
(arsenic, cadmium, chromium, lead, and nickel) were previously identified as COCs for the Operable Unit
3 (OUS) Surficial aquifer unit at the NPL site. In addition, one inorganic parameter (chromium) was
identified as a COC for the Quaternary alluvial aquifer. Additional site-specific groundwater data and
regulatory updates have become available since the initial designation of these inorganic parameters as
COCs. Based upon a review of the more current and updated data discussed below, it is apparent that
chromium should no longer be identified as a COC for the Quaternary alluvial aquifer. In addition, nickel
should no longer be considered a COC for the Surficial aquifer at the NPL site due to the change in
regulatory status as a drinking water contaminant.
Nickel in the Surficial Aquifer
The applicable or relevant and appropriate requirement (ARAR) established for nickel was the United
States Environmental Protection Agency (US EPA) maximum contaminant level (MCL). The former
US EPA MCL for nickel was 100 (ig/L. This MCL was "remanded" on February 9, 1995 (US EPA,
2002). As of the most recent update to the US EPA National Primary Drinking Water Standards
published in July 2003 (US EPA, 2003), there is no current MCL established for nickel. Because the
former US EPA MCL for nickel has been "remanded", there is no effective ARAR for nickel at the NPL
site. Therefore, nickel should be effectively removed as a COC in the Surficial aquifer at the NPL site.
Chromium in the Quaternary Alluvial Aquifer
Chromium was monitored in 27 Quaternary alluvial aquifer sampling locations during or before 1999.
The measured concentrations exceeded the US EPA MCL (100 (ig/L) in 10 of these monitoring locations
on at least one occasion. Historic data collected between 1997 and 2003 for all 27 of these locations is
presented in Table A-l. Data for only those monitoring locations that exceeded the US EPA MCL on at
least one occasion are presented in Table A-2. As shown in Table A-2, the last sample to exceed the US
EPA MCL was collected in 1999 (SLOW11, 139 ng/L). Six other locations (LF4-24, LF4-25, LF4-27,
L:\Work\Projects\75279\WordProc\FinalROD\FinalCOCAppendixA.doc A-l 9/13/2004
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Final
Appendix A -Review of Inorganic Chemicals of Concern (nickel and chromium)
Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
LF4WP5, LF4WP6, and SLOW13) reported exceedances in 1997 and/or 1998, but not in 1999 or later.
The three remaining locations (LF4-12, LF4WP7, and LF4WP8) have reported no exceedances since
1997.
Based on the data presented in Table A-2, it is clear that the concentrations of chromium in the
Quaternary alluvial aquifer have declined to levels consistently below the US EPA MCL of 100 (ig/L.
Only one previous monitoring location (SLOW 11) reported an exceedance in the most recently collected
sample (June 4, 1999). SLOW11 has not been sampled since 1999 because it has been abandoned. The
declining and consistently low concentrations reported in groundwater samples collected from the
Quaternary Alluvial aquifer are strong indicators that chromium has been attenuated by natural processes
(such as adsorption and dilution) and has effectively met the MCL (100 (ig/L) at the NPL site. Because
natural attenuation has occurred and 100% of the groundwater samples collected since the year 2000 have
been below the ARAR (MCL of 100 (ig/L), this parameter should no longer be identified as a COC within
the Quaternary alluvial aquifer at the NPL site.
L:\Work\Projects\75279\WordProc\FinalROD\FinalCOCAppendixA.doc A-2 9/13/2004
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Final
Appendix A -Review of Inorganic Chemicals of Concern (nickel and chromium)
Record of Decision (ROD) for the National Priorities List (NPL) Site, Operable Units (OUs) 1 and 3
Robins Air Force Base
Warner Robins, Georgia
REFERENCES
US EPA, 2002, Consumer Fact sheet on Nickel, (November 2002).
US EPA, 2003, US EPA National Primary Drinking Water Standards, Maximum Contaminant Levels,
EPA 816-F-03-016 (June 2003).
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
LF4-4
LF4-6
LF4-9
LF4-12
LF4-15
LF4-16
LF4-17
Date
14-Mar-97
24-Apr-98
02-Jun-99
22-May-OO
07-May-Ol
14_Mar-97
24-Apr-98
02-Jun-99
22-May-OO
07-May-Ol
03-May-02
04-May-03
17-Mar-97
25-Apr-98
02-Jun-99
18-May-OO
02-May-Ol
16-Mar-97
26-Apr-98
08-Jun-99
17-May-OO
02-May-Ol
25-Mar-97
28-Apr-98
07-Jun-99
18-May-OO
02-May-Ol
24-Mar-97
05-May-98
02-Jun-99
18-May-OO
03-May-Ol
Ol-May-02
03-May-OS
24-Mar-97
28-Apr-98
06-Jun-99
17-May-OO
03-May-Ol
Ol-May-02
06-May-03
Result (ug/L)
1.5
3.8
0.8
0.7
1.2
1.5
1.9
1.4
<0.7
1.6
0.9
1.31
1.2
0.8
0.6
1.2
8.0
3.2
<1.5
2.2
<0.7
17.8
17.6
8.5
1.1
0.7
2.2
6.0
7.1
18.9
O.7
1.3
5.60
0.8
4.1
20
9.1
1.0
2.1
2.60
5.21
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
LF4-18
LF4-19
LF4-21
LF4-23
LF4-24
LF4-25
LF4-26
LF4-27
Date
25-Mar-97
04-May-98
07-Jun-99
17-May-OO
03-May-Ol
02-May-02
05-May-OS
24-Mar-97
05-May-98
07-Jun-99
17-May-OO
02-May-Ol
02-May-02
07-May-03
17-Mar-97
27-Apr-98
05-Jun-99
18-May-OO
03-May-Ol
16-Mar-97
25-Apr-98
04-Jun-99
18-May-OO
03-May-Ol
02-May-02
OS-May-03
15-Mar-97
25-Apr-98
02-Jun-99
15-Mar-97
28-Apr-98
02-Jun-99
18-May-OO
03-May-Ol
17-Mar-97
23-Apr-98
07-Jun-99
16-Mar-97
30-Apr-98
07-Jun-99
18-May-OO
03-May-Ol
02-May-02
02-May-03
Result (ug/L)
<1.1
1.3
0.7
<0.7
<0.5
<0.7
<0.8
7.3
0.5
0.7
0.7
<0.5
<0.7
1.83
<1.1
5.4
5.1
1.3
22.0
<1.1
1.7
1.2
<0.7
1.1
0.7
0.8
91.4
118
15.9
19.1
261
0.5
0.7
0.8
21.5
24.1
11.5
17.4
143
2.0
0.7
3.2
0.7
3.19
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
LF4-30
LF4-31
LF4WP1
LF4WP2
LF4WP3
LF4WP4
LF4WP5
LF4WP6
Date
17-Mar-97
04-May-98
05-Jun-99
18-May-OO
03-May-Ol
02-May-02
OS-May-03
17-Mar-97
04-May-98
05-Jun-99
15-Mar-97
27-Apr-98
03-Jun-99
19-May-OO
04-May-Ol
03-May-02
04-May-03
25-Mar-97
05-May-98
07-Jun-99
20-May-OO
04-May-Ol
04-May-03
18-Mar-97
26-Apr-98
07-Jun-99
20-May-OO
04-May-Ol
18-Mar-97
25-Apr-98
04-Jun-99
19-May-OO
04-May-Ol
15-Mar-97
26-Apr-98
04-Jun-99
17-Mar-97
27-Apr-98
05-Jun-99
20-May-OO
04-May-Ol
Result (ug/L)
<1.1
14.5
1.0
<0.7
1.8
1.20
0.85
6.2
3.7
6.0
50.7
0.9
1.2
22.1
4.4
2.3
2.31
5.0
6.9
6.0
3.8
1.8
4.84
9.6
2.6
21.1
3.9
2.1
3.3
2.2
8.0
54.8
15.6
761
10.1
6.0
2140
316
42.9
16.0
90.3
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
LF4WP7
LF4WP8
LF4WP9
LF4WP10
LF4WP11
LF4WP12
RI1OW3
Date
18-Mar-97
28-Apr-98
06-Jun-99
20-May-OO
04-May-Ol
02-May-02
04-May-03
15-Mar-97
25-Apr-98
03-Jun-99
20-May-OO
05-May-Ol
03-May-02
03-May-OS
16-Mar-97
27-Apr-98
04-Jun-99
20-May-OO
05-May-Ol
03-May-02
OS-May-03
18-Mar-97
27-Apr-98
06-Jun-99
21-May-OO
06-May-Ol
02-May-02
05-May-OS
18-Mar-97
05-May-98
06-Jun-99
21-May-OO
06-May-Ol
02-May-02
05-May-OS
18-Mar-97
05-May-98
06-Jun-99
19-May-OO
04-May-Ol
03-May-02
02-May-03
26-Mar-97
04-May-98
08-Jun-99
Result (ug/L)
25.2
1.7
5.0
<0.7
2.1
5.20
1.23
3.8
6.0
2.8
2.2
2.0
2.89
4.47
3.5
2.6
2.6
1.2
0.5
2.58
2.25
2.4
0.9
1.5
0.8
0.5
3.64
3.78
2.1
1
1.8
1.1
0.5
O.7
10.9
2.8
O.3
14.7
2.3
3.0
8.37
4.5
1.5
O.3
0.4
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
RI1OW4
RW1
RW2
RW3
Date
26-Mar-97
06-May-98
08-Jun-99
13-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
21-May-OO
05-May-Ol
02-May-02
Ol-May-03
16-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
22-May-OO
04-May-Ol
02-May-02
Ol-May-03
15-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
20-May-OO
06-May-Ol
Ol-May-02
Ol-May-03
Result (ug/L)
15.7
1.4
4.0
1.3
<10
<10
0.6
<10
<10
<10
1.8
<10
1.1
<0.5
<10
1.21
2.9
<10
<10
1.3
<10
<10
<10
1.7
<10
<0.7
<0.5
1.65
<0.8
2.3
<10
<10
0.5
<10
<10
<10
1.6
<10
<0.7
<0.5
0.8
1.74
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
RW4
RW5
RW6
Date
15-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
20-May-OO
06-May-Ol
Ol-May-02
Ol-May-03
16-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
20-May-OO
06-May-Ol
03-May-02
Ol-May-03
17-Mar-97
22-Oct-97
07-Jan-98
06-May-98
06-Aug-98
ll-Nov-98
08-Mar-99
06-May-99
07-Feb-OO
20-May-OO
06-May-Ol
03-May-02
Ol-May-03
Result (ug/L)
9.6
<10
<10
1.8
<10
<10
<10
1.5
<10
<0.7
<0.5
<0.7
<0.8
1.4
<10
<10
0.3
<10
<10
<10
1.6
<10
<0.7
0.8
0.99
<0.8
<1.1
<10
<10
<0.3
<10
<10
<10
0.4
<10
<0.7
0.7
0.92
0.94
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Table A-l
Historic Data for Chromium in Quaternary Alluvial Aquifer
Monitoring Locations for OU3
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
SLOW?
SLOW9
SLOW11
SLOW13
SLOW14
Date
14_Mar-97
24-Apr-98
02-Jun-99
15-Mar-97
25-Apr-98
04-Jun-99
15-Mar-97
25-Apr-98
04-Jun-99
25-Mar-97
07-May-98
07-Jun-99
15-Mar-97
25-Apr-98
03-Jun-99
Result (ug/L)
<1.1
4.1
0.3
2.9
<1.7
1.4
1.5
<2.4
139
2230
7.9
2.1
8.0
3.1
0.3
Notes:
1) Chromium Maximum Contaminant Level = 100 |ig/L; US EPA National
Primary Drinking Water Standards, EPA 816-F-03-016 (US EPA, June 2003).
2) All Monitoring Locations Sampled since 1997.
3) Bolded values indicate detections.
4) Shaded areas indicate concentrations exceeding MCL.
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Table A-2
Historic Data for Chromium in Quaternary Alluvial Aquifer Monitoring Locations
for OU3 Exceeding the MCL Historically
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
LF4-12
LF4-24
LF4-25
LF4-27
LF4WP5
LF4WP6
LF4WP7
LF4WP8
Currently Monitored
No
No
No
Yes
No
No
Yes
Yes
Date
16-Mar-97
26-Apr-98
08-Jun-99
17-May-OO
02-May-Ol
15-Mar-97
25-Apr-98
02-Jun-99
15-Mar-97
28-Apr-98
02-Jun-99
18-May-OO
03-May-Ol
16-Mar-97
30-Apr-98
07-Jun-99
18-May-OO
03-May-Ol
02-May-02
02-May-03
15-Mar-97
26-Apr-98
04-Jun-99
17-Mar-97
27-Apr-98
05-Jun-99
20-May-OO
04-May-Ol
18-Mar-97
28-Apr-98
06-Jun-99
20-May-OO
04-May-Ol
02-May-02
04-May-03
15-Mar-97
25-Apr-98
03-Jun-99
20-May-OO
05-May-Ol
03-May-02
03-May-OS
Result Qig/L)
3.2
<1.5
2.2
0.7
17.8
91.4
118
15.9
19.1
261
0.5
0.7
0.8
17.4
143
2.0
0.7
3.2
0.7
3.19
761
10.1
6.0
2140
316
42.9
16.0
90.3
25.2
1.7
5.0
0.7
2.1
5.20
1.23
3.8
6.0
2.8
2.2
2.0
2.89
4.47
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Table A-2
Historic Data for Chromium in Quaternary Alluvial Aquifer Monitoring Locations
for OU3 Exceeding the MCL Historically
Record of Decision for the NPL Site, Operable Units (OUs) 1 and 3
Robins AFB, Georgia
Location
SLOW 11
SLOW13
Currently Monitored
Abandoned
Abandoned
Date
15-Mar-97
25-Apr-98
04-Jun-99
25-Mar-97
07-May-98
07-Jun-99
Result Qig/L)
1.5
<2.4
139
2230
7.9
2.1
Notes:
1) Chromium Maximum Contaminant Level (MCL) = 100 |ig/L; US EPA National Primary Drinking Water
Standards, EPA 816-F-03-016 (US EPA, June 2003).
2) Bolded values indicate detections.
3) Shaded areas indicate concentrations exceeding MCL.
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