PB95-964621
EPA/ROD/R10-95/135
May 1996
EPA Superfund
Record of Decision:
Elmendorf Air Force Base
Operable Unit 4, AK
9/26/1995
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UNITED STATES AIR FORCE
ELMENDORF AIR FORCE BASE, ALASKA
ENVIRONMENTAL RESTORA TION PROGRAM
RECORD OF DECISION
OPERABLE UNIT 4
FINAL
SEPTEMBER 1995
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[This page intentionally left blank.]
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TABLE OF CONTENTS
Page
PARTI. DECLARATION
PART II. DECISION SUMMARY
1.0 SITE DESCRIPTION ... r 1-1
1.1 Physical Description 1-1
1.2 Land Use ; 1-4
1.3 Hydrogeology and Groundwater Use 1-4
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-1
2.1 Identification and Activities Leading to Current Contamination at OU 4 .... 2-1
2.2 Regulatory and Enforcement History . 2-3
2.3 Role of Response Action 2-6
2.4 Community Participation 2-6
3.0 SITE CONTAMINATION, RISKS, AND AREAS REQUIRING RESPONSE
ACTION 3-1
3.1 Nature and Extent of Contamination 3-1
3.1.1 Groundwater 3-4
3.1.2 Soils .' 3-20
3.2 Risk Evaluation 3-44
3.2.1 Human Health Risk Assessment (HRE) 3-51
3.2.2 Environmental Risk Assessment (ERA) 3-54
3.3 Summary 3-57
4.0 REMEDIAL ACTION OBJECTIVES, ALTERNATIVES, AND
COMPARATIVE ANALYSIS 4-1
4.1 Contaminants of Concern (COCs) 4-1
4.2 Remedial Action Objectives 4-1
4.3 Alternatives 4-4
4.4 Summary of Comparative Analysis of Alternatives 4-13
4.4.1 Threshold Criteria 4-13
4.4.2 Primary Balancing Criteria 4-16
4.4.3 Modifying Criteria 4-20
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TABLE OF CONTENTS (Continued)
Page
5.0 SELECTED REMEDY 5-1
5.1 Statutory Determinations 5-5
5.1.1 Protective of Human Health and the Environment 5-7
5.1.2 Applicable or Relevant and Appropriate Requirements (ARARs) ... 5-8
5.1.3 Cost Effectiveness 5-8
5.1.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable 5-10
5.1.5 Preference for Treatment as a Principal Element 5-10
5.2 Document of Significant Changes 5-11
PART III. RESPONSIVENESS SUMMARY
APPENDED A: OU 4 ADMINISTRATIVE RECORD INDEX
u
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LIST OF FIGURES
Page
Figure 1-1 Location Map of Elmendorf AFB, Alaska 1-2
Figure 1 -2 Location of Operable Unit 4 West and Operable Unit 4 East
Study Areas, Elmendorf AFB, AK 1-3
Figure 1-3 Hydrogeologic Conceptual Model 1-5
Figure 3-1 A Schematic of Principal Transport Mechanisms in Operable
Unit 4, Elmendorf AFB, AK 3-2
Figure 3-2 Location of OU 4 Groundwater Contaminant Plumes,
Elmendorf AFB, AK 3-5
Figure 3-3 Fire Training Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-9
Figure 3-4 Hangar 14 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-12
Figure 3-5 Hangar 11 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-14
Figure 3-6 Hangar 8/10 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-15
Figure 3-7 Hangar 15/Building 43-410 Area Groundwater Plume,
Elmendorf AFB, AK 3-18
Figure 3-8 Location of Soil ACM Exceedances at the Fire Training Area,
Elmendorf AFB, AK 3-27
Figure 3-9 Location of Soil ACM Exeeedances in the Hangar 10/11 Area,
Elmendorf AFB, AK 3-37
Figure 3-10 Location of Soil ACM Exceedances at the Asphalt Drum Storage Area,
Elmendorf AFB, AK 3-45
111
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LIST OF FIGURES (continued)
Page
Figure 5-1 A Schematic of Preferred Alternatives for Operable Unit 4,
Elmendorf AFB, AK 5-4
LIST OF TABLES
Page
2-1 Former Source Areas at Operable Unit 4, Elmendorf AFB, AK 2-5
3-1 Fire Training Area Organic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK - ; 3-7
3-2 Hangar 14 Benzene Plume Area Organic and Inorganic Groundwater
Results for Contaminants of Potential Concern, Elmendorf AFB, AK 3-11
3-3 Hangar 11 Plume Area Organic Groundwater Results for Contaminant
of Potential Concern, Elmendorf AFB, AK 3-13
3-4 Hangar 8/10 Plume Area Organic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK 3-16
3-5 Hangar 15/Building 43-410 Plume Area Organic Groundwater Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-19
3-6 Fire Training Area Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-21
3-7 Fire Training Area Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-23
3-8 Hangar 14 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-28
IV
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LIST OF TABLES (continue)
Page
3-9 Hangar 14 Organic and Inorganic Subsurface Soil Results for Contaminants
of Potential Concern, Elmendorf AFB, AK 3-30
3-10 Hangar 10/11 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-32
3-11 Hangar 10/11 Organic and Inorganic Subsurface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-34
3-12 Hangar 8 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-38
3-13 Hangar 8 Organic and Inorganic Subsurface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK ; 3-40
3-14 Hangar 15/Building 43-410 Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AR 3-41
3-15 Hangar 15/Building 43-410 Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-43
3-16 Asphalt Drum Storage Area Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-46
3-17 Asphalt Drum Storage Area Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-49
3-18 Exposure Assumptions for OU 4 3-52
3-19 Summary of Human Health Risks at Operable Unit 4, Elmendorf AFB, AK 3-55
4-1 Summary of Contaminants of Concern Analysis, Operable Unit 4,
Elmendorf AFB, AK 4-2
4-2 Costs and Time to Cleanup for Alternative G2 and S2, Operable
Unit 4, Elmendorf AFB, AK 4-7
4-3 Costs and Time to Cleanup for Alternative G3 and S3, Operable
Unit 4, Elmendorf AFB, AK 4-8
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LIST OF TABLES (continued)
Page
4-4 Costs and Time to Cleanup for Alternative G4 and S4, Operable
Unit 4, Elmendorf AFB, AK 4-10
4-5 Costs and Time to Cleanup for Alternative S5, Operable
Unit 4, Elmendorf AFB, AK 4-12
5-1 Selected Remedy for Operable Unit 4, Elmendorf AFB, AK 5-2
5-2 Chemical-Specific ARARs for Groundwater and Soils, Operable Unit 4,
Elmendorf AFB, AK 5-6
5-3 Identification of Action-Specific ARARs, Operable Unit 4, Elmendorf AFB, AK .. 5-9
VI
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ACRONYM LIST
AAC
ACM
ADEC
ADSA
AFB
ARARs
BESG
CERCLA
CFR
cm/sec
COC
COPC
COE
CSF
DCA
DCE
ELCR
ERA
EQ
FFA
FS
ft/day
fWday
FTA
HEAST
HI
HRA
HVOC
IRIS
IRP
ICIR
LFI
MCL
mg/kg
NCP
NFA
NHVOC
O&M
OU
PCE
Alaska Administrative Code
Alaska Cleanup Matrix for non-UST soils.
Alaska Department of Environmental Conservation
Asphalt Drum Storage Area
Air Force Base
Applicable or Relevant and Appropriate Requirements
Elmendorf Bioenvironmental Engineering Services Group
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
Centimeter Per Second
Contaminant of Concern
Contaminant of Potential Concern
Corps of Engineers
Cancer Slope Factor
Dichloroethane
Dichloroethene
Excess Lifetime Cancer Risks
Ecological Risk Assessment
Ecological Quotients
Federal Facilities Agreement
Feasibility Study
Feet Per Day
Feet Squared Per Day
Fire Training Area
Health Effects Assessment Summary Table
Hazard Index
Health Risk Assessment
Halogenated Volatile Organic Compound
Integrated Risk Information System
Installation Restoration Program
Institutional Controls with Intrinsic Remediation
Limited Field Investigation
Maximum Contaminant Level
Milligrams Per Kilogram
National Oil and Hazardous Substances Pollution Contingency Plan
No Further Action
Non Halogenated Volatile Organic Compounds
Operation and Maintenance
Operable Unit
Tetrachloroethene
VII
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ACRONYMS (Continued)
POL
ppvm
RCRA
RfD
RI
RME
ROD
SARA
SERA
SVOC
TBC
TCA
TCE
UCL
ug/L
USEPA
UST
VOC
Petroleum Oil Lubricant
Parts Per Million by Volume
Resource Conservation and Recovery Act
Reference Dose
Remedial Investigation
Reasonable Maximum Exposure
Record of Decision
Superfund Amendments and Reauthorization Act
State/Environmental Restoration Agreement
Semi-Volatile Organic Compound
To-Be-Considered
1,1,1 -Trichloroethane
Trichloroethene
Upper Confidence Limit
Micrograms Per Liter
U.S. Environmental Protection Agency
Underground Storage Tank
Volatile Organic Compound
Vlll
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PART I. DECLARATION
SITE NAME AND LOCATION
Elmendorf Air Force Base (AFB)
Operable Unit (OU) 4
Elmendorf Air Force Base, Alaska
STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the selected remedial action for OU 4
at Elmendorf AFB. It was developed in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA) as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA), 42 U.S.C. §9601 et seq..
and, to the extent practicable, in accordance with the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 CFR §300 et seq. The attached administrative record
index (Appendix A) identifies the documents upon which the selection of the remedial action
was based.
The selected remedy includes the following: 1) active bioventing for deep
soils (greater than five feet below the ground surface) at the Fire Training Area (FTA),
Hangar 11, and the Asphalt Drum Storage Area (ADSA), and 2) institutional controls with
intrinsic remediation for any remaining deep soil contamination, all shallow soils (ground
surface to five feet below ground surface), and all groundwater within the upper aquifer.
The U.S. Air Force (USAF), the U.S. Environmental Protection Agency (USEPA), and the
State of Alaska, through the Department of Environmental Conservation (ADEC), concur
with the selected remedy.
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ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances including halogenated
volatile organic compounds (HVOCs), fuels, and fuel constituents from this OU, if not
addressed by implementing the response action selected in this ROD, could present an
imminent or substantial endangerment to public health, welfare, or the environment. Specific
hazardous substances include constituents such as benzene, trichloroethene, tetrachloroethene,
and vinyl chloride.
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy was chosen from many alternatives as the best method of
addressing contaminated soil and ground water in OU 4. It addresses the risks to health and
the environment caused by the hypothetical exposure of a future resident to contaminated
groundwater or soils. The selected remedy addresses this risk by reducing contamination to
below cleanup levels established for OU 4.
The major components of the selected remedy include:
Groundwater
• Institutional controls on land use and water use restrictions will restrict
access to the contaminated groundwater throughout OU 4 until cleanup
levels have been achieved.
• Groundwater will be monitored semi-annually to evaluate contaminant
migration and timely reduction of contaminant concentrations by
intrinsic remediation. If cleanup levels are not being achieved, further
remedial action will be evaluated. Five-year reviews will also assess
the protectiveness of the remedial action, as long as contamination
remains above cleanup levels.
• All groundwater is expected to be cleaned up within thirteen years.
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Soil
• Institutional controls on land use will continue to restrict access to the
contaminated shallow soils throughout OU 4 until cleanup levels have
been achieved.
• Deep soils at the FTA, the ADSA, and Hangar 11 will be treated with
bioventing to accelerate degradation of contaminants in those locations.
Deep soils at other source areas will be allowed to degrade through
intrinsic remediation.
• Both shallow and deep soils will be monitored bi-annually to evaluate
contaminant migration and timely reduction of contaminant concentra-
tions by bioventing and intrinsic remediation. If cleanup levels are not
being achieved, further remedial action will be evaluated. This will
include five-year reviews to assess the protectiveness of the remedial
action, as long as contamination remains above cleanup levels. When
concentrations in the bioventing areas are below cleanup levels, bio-
venting will be discontinued.
• All soils are expected to be cleaned up within eleven years.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, com-
plies with federal and state requirements that are legally applicable or relevant and appropri-
ate to remedial action, and is cost-effective. For contaminated soil, this remedy utilizes
permanent solutions and alternative treatment technologies to the maximum extent
practicable, and satisfies the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element, however, because treatment of
ground water was found not to be practicable, this remedy does not satisfy the statutory
preference for treatment.
Because the remedy will result in contaminants remaining on-site above health-
based levels, a review will be conducted within five years after commencement of remedial
action. The review will ensure that the remedy continues to provide adequate protection of
human health and the environment.
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the
United States Environmental Protection Agency on the Record of Decision for
Operable Unit 4 at Elmendorf Air Force Base. The Alaska Department of
Environmental Conservation concurs with the Record of Decision.
JOHN IB. LORBER, General, USAF
Commander, Pacific Air Forces
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 4 at
Elmendorf Air Force Base. The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
CLARKE
Regional Administrator
Region X
U.S. Environmental Protection Agency
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 4 at
Ehnendorf Air Force Base. The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
- lo
KURT FREDRKSSON Date
Director, Spill Prevention and Response
Alaska Department of Environmental Conservation
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PART H. DECISION SUMMARY
This Decision Summary provides an overview of the problems posed by the
contaminants at Elmendorf Air Force Base (AFB) Operable Unit (OU) 4. It identifies the
areas considered for remedial response, describes the remedial alternatives considered, and
analyzes those alternatives compared to the criteria set forth in the National Contingency Plan
(NCP). The Decision Summary explains the rationale for selecting the remedy, and how the
remedy satisfies the statutory requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA);
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UNITED STATES AIR FORCE
ELMENDORF AIR FORCE BASE, ALASKA
ENVIRONMENTAL RESTORA TION PROGRAM
RECORD OF DECISION
OPERABLE UNIT 4
FINAL
SEPTEMBER 1995
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TABLE OF CONTENTS
Page
PART I. DECLARATION
PART II. DECISION SUMMARY
1.0 SITE DESCRIPTION 1-1
1.1 Physical Description 1-1
1.2 Land Use ; 1-4
1.3 Hydrogeology and Groundwater Use 1-4
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-1
2.1 Identification and Activities Leading to Current Contamination at OU 4 .... 2-1
2.2 Regulatory and Enforcement History 2-3
2.3 Role of Response Action 2-6
2.4 Community Participation 2-6
3.0 SITE CONTAMINATION, RISKS, AND AREAS REQUIRING RESPONSE
ACTION 3-1
3.1 Nature and Extent of Contamination 3-1
3.1.1 Groundwater 3-4
3.1.2 Soils ;..... 3-20
3.2 Risk Evaluation 3-44
3.2.1 Human Health Risk Assessment (HRE) ' 3-51
3.2.2 Environmental Risk Assessment (ERA) 3-54
3.3 Summary 3-57
4.0 REMEDIAL ACTION OBJECTIVES, ALTERNATIVES, AND
COMPARATIVE ANALYSIS 4-1
4.1 Contaminants of Concern (COCs) 4-1
4.2 Remedial Action Objectives 4-1
4.3 Alternatives 4-4
4.4 Summary of Comparative Analysis of Alternatives 4-13
4.4.1 Threshold Criteria 4-13
4.4.2 Primary Balancing Criteria 4-16
4.4.3 Modifying Criteria 4-20
-------
TABLE OF CONTENTS (Continued)
Page
5.0 SELECTED REMEDY 5-1
5.1 Statutory Determinations 5-5
5.1.1 Protective of Human Health and the Environment 5-7
5.1.2 Applicable or Relevant and Appropriate Requirements (ARARs) ... 5-8
5.1.3 Cost Effectiveness 5-8
5.1.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable 5-10
5.1.5 Preference for Treatment as a Principal Element 5-10
5.2 Document of Significant Changes 5-11
PART III. RESPONSIVENESS SUMMARY
APPENDIX A: OU 4 ADMINISTRATIVE RECORD INDEX
11
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LIST OF FIGURES
Page
Figure 1-1 Location Map of Elmendorf AFB, Alaska 1-2
Figure 1-2 Location of Operable Unit 4 West and Operable Unit 4 East
Study Areas, Elmendorf AFB, AK 1-3
Figure 1-3 Hydrogeologic Conceptual Model 1-5
Figure 3-1 A Schematic of Principal Transport Mechanisms in Operable
Unit 4, Elmendorf AFB, AK 3-2
Figure 3-2 Location of OU 4 Groundwater Contaminant Plumes,
Elmendorf AFB, AK 3-5
Figure 3-3 Fire Training Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-9
Figure 3-4 Hangar 14 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-12
Figure 3-5 Hangar 11 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-14
Figure 3-6 Hangar 8/10 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK 3-15
Figure 3-7 Hangar 15/Building 43-410 Area Groundwater Plume,
Elmendorf AFB, AK 3-18
Figure 3-8 Location of Soil ACM Exceedances at the Fire Training Area,
Elmendorf AFB, AK 3-27
Figure 3-9 Location of Soil ACM Exeeedances in the Hangar 10/11 Area,
Elmendorf AFB, AK 3-37
Figure 3-10 Location of Soil ACM Exceedances at the Asphalt Drum Storage Area,
Elmendorf AFB, AK 3-45
in
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LIST OF FIGURES (continued)
Page
Figure 5-1 A Schematic of Preferred Alternatives for Operable Unit 4,
Elmendorf AFB, AK 5-4
LIST OF TABLES
Page
2-1 Former Source Areas at Operable Unit 4, Elmendorf AFB, AK 2-5
3-1 Fire Training Area Organic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK .- 3-7
3-2 Hangar 14 Benzene Plume Area Organic and Inorganic Groundwater
Results for Contaminants of Potential Concern, Elmendorf AFB, AK 3-11
3-3 Hangar 11 Plume Area Organic Groundwater Results for Contaminant
of Potential Concern, Elmendorf AFB, AK 3-13
3-4 Hangar 8/10 Plume Area Organic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK 3-16
3-5 Hangar 15/Building 43-410 Plume Area Organic Groundwater Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-19
3-6 Fire Training Area Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-21
3-7 Fire Training Area Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-23
3-8 Hangar 14 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-28
IV
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LIST OF TABLES (continue)
Page
3-9 Hangar 14 Organic and Inorganic Subsurface Soil Results for Contaminants
of Potential Concern, Elmendorf AFB, AK 3-30
3-10 Hangar 10/11 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-32
3-11 Hangar 10/11 Organic and Inorganic Subsurface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-34
3-12 Hangar 8 Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-38
3-13 Hangar 8 Organic and Inorganic Subsurface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK 3-40
3-14 Hangar 15/Building 43-410 Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AR 3-41
3-15 Hangar 15/Building 43-410 Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-43
3-16 Asphalt Drum Storage Area Organic and Inorganic Surface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-46
3-17 Asphalt Drum Storage Area Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern, Elmendorf AFB, AK 3-49
3-18 Exposure Assumptions for OU 4 3-52
3-19 Summary of Human Health Risks at Operable Unit 4, Elmendorf AFB, AK 3-55
4-1 Summary of Contaminants of Concern Analysis, Operable Unit 4,
Elmendorf AFB, AK .... 4-2
4-2 Costs and Time to Cleanup for Alternative G2 and S2, Operable
Unit 4, Elmendorf AFB, AK 4-7
4-3 Costs and Time to Cleanup for Alternative G3 and S3, Operable
Unit 4, Elmendorf AFB, AK 4-8
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LIST OF TABLES (continued)
Page
4-4 Costs and Time to Cleanup for Alternative G4 and S4, Operable
Unit 4, Elmendorf AFB, AK 4-10
4-5 Costs and Time to Cleanup for Alternative S5, Operable
Unit 4, Elmendorf AFB, AK 4-12
5-1 Selected Remedy for Operable Unit 4, Elmendorf AFB, AK 5-2
5-2 Chemical-Specific ARARs for Groundwater and Soils, Operable Unit 4,
Elmendorf AFB, AK 5-6
5-3 Identification of Action-Specific ARARs, Operable Unit 4, Elmendorf AFB, AK .. 5-9
VI
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ACRONYM LIST
AAC
ACM
ADEC
ADSA
AFB
ARARs
BESG
CERCLA
CFR
cm/sec
coc
COPC
COE
CSF
DCA
DCE
ELCR
ERA
EQ
FFA
FS
ft/day
fWday
FTA
HEAST
HI
HRA
HVOC
IRIS
IRP
ICIR
LFI
MCL
mg/kg
NCP
NFA
NHVOC
O&M
OU
PCE
Alaska Administrative Code
Alaska Cleanup Matrix for non-UST soils.
Alaska Department of Environmental Conservation
Asphalt Drum Storage Area
Air Force Base
Applicable or Relevant and Appropriate Requirements
Elmendorf Bioenvironmental Engineering Services Group
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
Centimeter Per Second
Contaminant of Concern
Contaminant of Potential Concern
Corps of Engineers
Cancer Slope Factor
Dichloroethane
Dichloroethene
Excess Lifetime Cancer Risks
Ecological Risk Assessment
Ecological Quotients
Federal Facilities Agreement
Feasibility Study
Feet Per Day
Feet Squared Per Day
Fire Training Area
Health Effects Assessment Summary Table
Hazard Index
Health Risk Assessment
Halogenated Volatile Organic Compound
Integrated Risk Information System
Installation Restoration Program
Institutional Controls with Intrinsic Remediation
Limited Field Investigation
Maximum Contaminant Level
Milligrams Per Kilogram
National Oil and Hazardous Substances Pollution Contingency Plan
No Further Action
Noh Halogenated Volatile Organic Compounds
Operation and Maintenance
Operable Unit
Tetrachloroethene
vn
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ACRONYMS (Continued)
POL
ppvm
RCRA
RfD
RI
RME
ROD
SARA
SERA
SVOC
TBC
TCA
TCE
UCL
USEPA
UST
VOC
Petroleum Oil Lubricant
Parts Per Million by Volume
Resource Conservation and Recovery Act
Reference Dose
Remedial Investigation
Reasonable Maximum Exposure
Record of Decision
Superfund Amendments and Reauthorization Act
State/Environmental Restoration Agreement
Semi-Volatile Organic Compound
To-Be-Considered
1,1,1-Trichloroethane
Trichloroethene
Upper Confidence Limit
Micrograms Per Liter
U.S. Environmental Protection Agency
Underground Storage Tank
Volatile Organic Compound
Vlll
-------
PART I. DECLARATION
SITE NAME AND LOCATION
Elmendorf Air Force Base (AFB)
Operable Unit (OU) 4
Elmendorf Air Force Base, Alaska
STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the selected remedial action for OU 4
at Elmendorf AFB. It was developed in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA) as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA), 42 U.S.C. §9601 et seq..
and, to the extent practicable, in accordance with the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 CFR §300 et seq. The attached administrative record
index (Appendix A) identifies the documents upon which the selection of the remedial action
was based.
The selected remedy includes the following: 1) active bioventing for deep
soils (greater than five feet below the ground surface) at the Fire Training Area (FTA),
Hangar 11, and the Asphalt Drum Storage Area (ADSA), and 2) institutional controls with
intrinsic remediation for any remaining deep soil contamination, all shallow soils (ground
surface to five feet below ground surface), and all groundwater within the upper aquifer.
The U.S. Air Force (USAF), the U.S. Environmental Protection Agency (USEPA), and the
State of Alaska, through the Department of Environmental Conservation (ADEC), concur
with the selected remedy.
-------
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances including halogenated
volatile organic compounds (HVOCs), fuels, and fuel constituents from this OU, if not
addressed by implementing the response action selected in this ROD, could present an
imminent or substantial endangerment to public health, welfare, or the environment. Specific
hazardous substances include constituents such as benzene, trichloroethene, tetrachloroethene,
and vinyl chloride.
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy was chosen from many alternatives as the best method of
addressing contaminated soil and groundwater in OU 4. It addresses the risks to health and
the environment caused by the hypothetical exposure of a future resident to contaminated
groundwater or soils. The selected remedy addresses this risk by reducing contamination to
below cleanup levels established for OU 4.
The major components of the selected remedy include:
Groundwater
• • Institutional controls on land use and water use restrictions will restrict
access to the contaminated groundwater throughout OU 4 until cleanup
levels have been achieved.
• Groundwater will be monitored semi-annually to evaluate contaminant
migration and timely reduction of contaminant concentrations by
intrinsic remediation. If cleanup levels are not being achieved, further
remedial action will be evaluated. Five-year reviews will also assess
the protectiveness of the remedial action, as long as contamination
remains above cleanup levels.
• All groundwater is expected to be cleaned up within thirteen years.
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Soil
• Institutional controls on land use will continue to restrict access to the
contaminated shallow soils throughout OU 4 until cleanup levels have
been achieved.
• Deep soils at the FTA, the ADSA, and Hangar 11 will be treated with
bio venting to accelerate degradation of contaminants in those locations.
Deep soils at other source areas will be allowed to degrade through
intrinsic remediation.
• Both shallow and deep soils will be monitored bi-annually to evaluate
contaminant migration and timely reduction of contaminant concentra-
tions by bioventing and intrinsic remediation. If cleanup levels are not
being achieved, further remedial action will be evaluated. This will
include five-year reviews to assess the protectiveness of the remedial
action, as long as contamination remains above cleanup levels. When
concentrations in the bioventing areas are below cleanup levels, bio-
venting will be discontinued.
• All soils are expected to be cleaned up within eleven years.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, com-
plies with federal and state requirements that are legally applicable or relevant and appropri-
ate to remedial action, and is cost-effective. For contaminated soil, this remedy utilizes
permanent solutions and alternative treatment technologies to the maximum extent
practicable, and satisfies the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element, however, because treatment of
ground water was found not to be practicable, this remedy does not satisfy the statutory
preference for treatment.
Because the remedy will result in contaminants remaining on-site above health-
based levels, a review will be conducted within five years after commencement of remedial
action. The review will ensure that the remedy continues to provide adequate protection of
human health and the environment.
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the
United States Environmental Protection Agency on the Record of Decision for
Operable Unit 4 at Elmendorf Air Force Base. The Alaska Department of
Environmental Conservation concurs with the Record of Decision.
JOHN fe. LORBER, General, USAF
Commander, Pacific Air Forces
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 4 at
Elmendorf Air Force Base. The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
CLARKE
Regional Administrator
Region X
U.S. Environmental Protection Agency
Date
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 4
This signature sheet documents agreement between the U.S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 4 at
Elmendorf Air Force Base. The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
KURT FREDRIKSSON Date
Director, Spill Prevention and Response
Alaska Department of Environmental Conservation
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PART H. DECISION SUMMARY
. This Decision Summary provides an overview of the problems posed by the
contaminants at Elmendorf Air Force Base (AFB) Operable Unit (OU) 4. It identifies the
areas considered for remedial response, describes the remedial alternatives considered, and
analyzes those alternatives compared to the criteria set forth in the National Contingency Plan
(NCP). The Decision Summary explains the rationale for selecting the remedy, and how the
remedy satisfies the statutory requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA):
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1.0 SITE DESCRIPTION
The following subsections describe the physical description, land use, and
hydrogeology of OU 4, as well as groundwater use.
1.1 Physical Description
Elmendorf AFB is located approximately two miles north of downtown
Anchorage (Figure 1-1). The base provides defense for the United States through surveil-
lance, logistics, and communications support. OU 4 is located in the central portion of
Elmendorf AFB, and is situated near the main runways (Figure 1-2). OU 4 is .made up of
two geographic areas, OU 4 West and OU 4 East. The OU was divided into OU 4 West and
OU 4 East Study Areas during the Remedial Investigation (RI) based on the proximity of the
facilities being investigated to better characterize the nature and extent of contamination and
to better evaluate risk.
OU 4 West
7
OU 4 West is located on relatively flat terrain at an approximate elevation of
195 feet. The terrain slopes generally to the southwest. The boundary of OU 4 West
encompasses an area roughly 6000 feet by 2000 feet, approximately 275 acres. This area has
been cleared of most vegetation except for some grass. Most of the area within OU 4 is
paved or fenced and consists of an active runway and improved grounds and buildings.
There are five principal buildings located within OU 4 West: Hangars 8, 10, 11, 12, and
14. The Fire Training Area (FTA) is also located in OU 4 West (Figure 1-2). Each of the
five buildings located within OU 4 West and the FTA are former contaminant source areas.
OU4East
OU 4 East is also located on relatively flat terrain at an approximate elevation
1-1
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Alaska
Figure 1-1. Site Location Map, Elmendorf AFB, Anchorage, Alaska
1-2
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Triangle Lake
Hangar 14
r-OU 4
East
Fire Training A
Bums Road
Hangar 15/
Building 43-410
Asphalt Drum
Storage Area
Dovlj Highway
Eo»t/West Apron c
Llrrnndort Are Boundary
Municipality of I
Anchorage !
ELMENDORF AFB
OU 4 Study Areas
SCALE
3000
Figure 1-2. Location of Operable Unit 4 West and Operable Unit 4 East
Study Areas, Elmendorf AFB, AK
1-3
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of 195 feet, with the terrain sloping to the southwest. The OU 4 East boundary, as drawn, is
approximately 1500 feet by 2500 feet, or about 85 acres. The portion of OU 4 East west of
Hubble Road is improved with buildings and/or roads, parking aprons, and taxiways. There
are two principal buildings located within this area, Hangar 15 and Building 43-410 (Figure
1-2). The area around the buildings is cleared of vegetation except for grass. The area east
of Hubble Road is fairly densely vegetated with only a few roads and an easement and line of
the Alaska Railroad. Vegetation consists mostly of alder brush and birch woods. The only
exception is in the vicinity of the former Asphalt Drum Storage Area (ADSA), where the
area was cleared for the removal of asphalt drums and asphalt stained soil. Both the ADS A
and Hangar 15/Building 43-410 are former contaminant source areas.
1.2 Land Use
Land use for both OU 4 West and OU 4 East includes light industrial, aircraft
operations and maintenance, and airfield. Light industrial includes maintenance, storage, and
supply functions directly related to aircraft. The primary land use within OU 4 is for air-
fields, which includes active and inactive runways, taxiways, and parking aprons for aircraft.
Other land uses include designated outdoor recreation and open areas. The right-of-way for
the Alaska Railroad is located within OU 4 East (Figure 1-2). The Base Master Comprehen-
sive Plan has designated this area for airfield, and aircraft operations and maintenance in the
future. There are no known historic buildings, archaeologic sites, wetlands, floodplains, or
rare or endangered species in OU 4.
1.3 Hvdrogeologv and Groundwater Use
OU 4 is located in a glacial outwash plain composed predominantly of sand
and gravel. There are two aquifers underlying the area, an unconfined shallow aquifer and a
deep confined aquifer. The aquifers are separated by the Bootlegger Cove Formation, an
impermeable layer composed of silts and clays (Figure 1-3).
1-4
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ELMENDORF AFB
LEGEND
Hydrogeologic Conceptual Model
OU4 Study Areas
Water Table
Typically 30 to 60 feet
below ground surface
Bootlegger Cove Formation -
Typically about 50 feet thick
-Unconfined Aquifer
(Sand and Gravel)
Typically 10 to 80 feet thick
with about a 50 foot saturated
thickness
Confined Aquifer
(Sand) Found about 150 feet
below ground surface
and up to 550 feet thick
Figure 1-3. Location of Operable Unit 4 West and Operable Unit East
Study Areas, Elmendorf AFB, AK
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OU 4 West is situated on glacial outwash and alluvial deposits, consisting of
sands with varying amounts of gravel and silts. Sand with silt and gravel units comprise the
upper 10 to 20 feet of the aquifer and are underlain by gravel and sand units approximately
10 to 50 feet thick. The saturated interval marking the top of the unconfined aquifer varies
from approximately 30 feet below surface down to 60 feet below surface: The saturated
interval is approximately 50 feet thick. Groundwater flow direction is to the southwest, with
a gradient of near 4 feet per mile, increasing to 36 feet per mile towards Ship Creek. The
shallow unconfined aquifer is not used for any purpose on base. Its future use, even if the
aquifer was uncontaminated, is limited because of the higher yield of the deep, confined
aquifer. More detail on impacts in the shallow aquifer is provided in Section 3.0.
The shallow, unconfined aquifer in OU 4 West overlies the Bootlegger Cove
Formation. The formation consists of interbedded silts and clay deposits at depths approxi-
mately 30 to 125 feet below ground level. The average thickness of the formation in this
area is approximately 50 feet. The structural surface of the formation is irregular. Within
OU 4 West, the top of the Bootlegger Cove Formation is deepest hi the vicinity of the FTA
(at approximately 100 feet below ground surface) and near Hangar 14 (at 105 feet below
ground surface). Further toward the southwest, the formation becomes shallower. At
Hangar 8, this unit is at 39 feet below ground level.
OU 4 East is situated on glacial outwash and alluvial deposits of almost exclu-
sively sandy gravel with minor interbedded cobbles. The shallow unconfined aquifer consists
of primarily gravelly sands, and is believed to overlie the Bootlegger Cove Formation as in
OU 4 West. The presence of this aquitard has not been verified within OU 4 East, however,
the regional geology strongly supports its presence. The top of the Bootlegger Cove Forma-
tion is believed to occur at a depth greater than 120 feet below ground surface. Groundwater
flow direction in the shallow aquifer is to the west, with a gradient of 6.5 feet per mile in-
creasing toward Ship Creek. As at OU 4 West, the shallow unconfined aquifer at OU 4 East
is not used for any purpose on base. More detail on impacts is provided in Section 3.0.
1-6
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Hydraulic conductivity for the unconfined shallow aquifer in OU 4 ranges
from approximately l.OE-1 cm/sec to 3.0E-1 cm/sec. Transmissivity for the shallow aquifer
is estimated to range from approximately 17,000 to 45,000 frVday. .This is typical for gravel
and coarse sand aquifers. The average linear velocity is estimated to be 3.2 ft/day.
The deep aquifer at OU 4 underlies and is confined by the Bootlegger Cove
•Formation, and occurs at a depth of approximately 150 feet below ground surface. This
aquifer is up to 550 feet thick. While the Bootlegger Cove Formation forms the principal
confining unit, the confined aquifer may also be overlain by substantial thicknesses of other
fine grained materials. Groundwater flow in the aquifer is to the west-northwest toward
Knik Ann.
The deep aquifer supplies large quantities of water for light industrial use such
as air conditioning cooling water (no treatment), and washing aircraft and vehicles (chlorina-
tion only). There are three active base wells screened in the deep aquifer near OU 4, that
were sampled during the remedial investigation. Contamination attributable to OU 4 was not
found in these wells. Base Well 29 is located iipgradient from OU 4 at Building 42-500.
The two remaining wells are located downgradient of OU 4, Base Well 40 near Building 5-
800, and Base Well 42 near Building 11-200. These wells also provide water that, after
chlorination, is used for drinking water in several buildings.
Results from the hydraulic communication tests conducted at Base Well 42 in
an adjacent operable unit (OU 2) are applicable to OU 4. The results indicate there is no
communication between the shallow aquifer and the confined aquifer. This result, with con-
current information from sampling of the three base water supply wells screened in the deep
aquifer, demonstrate the competency of the Bootlegger Cove Formation as an aquitard
between the unconfined and confined aquifers.
1-7
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2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The following subsections detail the contaminant history of OU 4, the regula-
tory and enforcement history, the role of the response action, and the role of the community
in defining the response.
2.1 Identification of Activities Leading to Current Contamination at OU 4
As part of the ongoing mission at Elmendorf Air Force Base, aircraft are regu-
larly refueled, and many of the fuel lines and the associated valves and storage tanks are
located within OU 4. These fuel systems have, at tunes, leaked fuel into the soil and
groundwater surrounding these facilities. In addition, maintenance of these aircraft regularly
occurred at OU 4, and the waste management practices associated with these activities, such
as discharge of wastes into floor drains, have also resulted in releases of solvents and fuel-
related constituents. Finally, incomplete combustion of fuels at the FT A and waste manage-
ment activities at the former ADSA have also resulted in discharges of contaminants into the
soil and groundwater.
Over 30 underground storage tanks (USTs) are located within OU 4 West. An
additional nine are located hi OU 4 East. These tanks vary in size, up to a 25,000-gallon
capacity. Historical spills at OU 4 West included numerous small fuel spills (less than 1,000
gallons). Specific recovery activities for these spills have not been reported.
In OU 4 East, numerous gasoline and diesel spills have reportedly occurred in
the vicinity of the ADSA. In addition, asphalt drums stored at the ADSA leaked substantial
quantities of asphalt and fuel residuals onto the ground in that area.
The activities which contributed to past contamination at OU 4 are no longer
taking place. As far as fuel related leaks are concerned at OU 4, the valve pit at Hangar 11
was taken out of service. This valve pit served a line to three USTs, which have also been
2-1
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removed. In addition, all base USTs are being upgraded, all lines have been tested
(including those in the vicinity of Pumphouse 2), and all leaks have been repaired.
Discharge of waste into dry wells through floor drains no longer takes place at OU 4. Fire
training activities at the FTA ceased in 1991. Furthermore, a 22,000-gallon UST and the
associated excavated soil down to a depth of 12 feet below ground surface have been
removed in the immediate vicinity of the FTA. Finally, at the ADSA, all drums and the first
few inches of soil (including visible contamination) have been removed and the area has been
revegetated.
Environmental investigations have been conducted at OU 4 since the early-
1980s. Several studies discovered evidence of contamination in various parts of OU 4. The
majority of these investigations were broadly focused across Elmendorf AFB, and covered
only portions of the source areas currently included in OU 4.
The first investigation to examine contamination throughout the whole area
was done hi 1990 by Black and Veatch. The initial study was followed in 1992 by a Limited
Field Investigation (LFI) by CH2M Hill. Following the LFI, a full scale Remedial Investiga-
tion (RI) was conducted at OU 4 West and OU 4 East in 1993 by Radian Corporation. The
RI determined the nature and extent of contamination, and the potential risks to public health
and the environment. The results were compiled and analyzed in the RI report. Alternatives
for remedial action were evaluated in detail in the OU 4 Feasibility Study (FS), submitted
with the RI in September of 1994.
The RI/FS concluded that low levels of soil contamination were primarily the
result of vehicular traffic, road paving, and pesticide application. Several specific sources of
groundwater contamination were identified, including the training activities at the FTA, a
leaking 25,000-gallon UST and some buried drums near the FTA, leaking valve pits and
USTs at Hangar 11, leaking valve pits at Hangar 15, and a leaking pumphouse or piping near
Hangar 8. Solvent contamination at OU 4 East was attributed to dry wells (wells used to
allow waste water, used solvents, etc. to be absorbed by the ground) or an upgradient leach
2-2
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field located by Hangar 15, however, difficult drilling conditions precluded defining the
source for the groundwater plume in that area.
2.2 Regulatory and Enforcement History
Based on the results of environmental investigations, Elmendorf AFB was
listed on the National Priorities List by the U.S. Environmental Protection Agency (USEPA)
in August 1990. This listing designated the facility as a federal site subject to the remedial
response requirements of the Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization
Act of 1986 (SARA). On 22 November 1991, the U.S. Air Force (USAF), the USEPA, and
the Alaska Department of Environmental Conservation (ADEC) signed the Federal Facilities
Agreement (FFA) for Elmendorf AFB. The contaminated areas of Elmendorf AFB were
divided into seven OUs, each to be managed as a separate region and investigated according
to varying schedules.
Up until 1992, a total of ten facilities, including a pesticide mixing and storage
building, were considered to be part of OU 4. These included source areas SD24, SD25,
SD26, SD27, SD28, SD29, SD30, SD31, SS18 and SS63. These facilities were grouped into
an Operable Unit because of sharing a common conceptual model for potential contaminant
release to the environment, namely, discharge of chemicals to floor drains with potential
migration to the environment through dry wells, leach fields, french drains, or other similar
structures.
Based on the results of the LFI conducted in 1992, the focus of the investiga-
tion at OU 4 shifted away from the individual buildings and floor drains. The conclusions of
the LFI were that dry wells and leach fields were not the primary sources of contamination at
the OU. Other potential sources of contamination were identified, and recommendations
were made as to whether further investigation would be necessary at the individual facilities
within the OU. As a result of that study, four of the original facilities, SD26, SD27, SD30
2-3
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and SSI8, were recommended to receive No Further Action (NFA). Based on the LFI
results, No Further Action (NFA) Decision Documents were prepared and submitted in April
of 1993 for SD26, SD27, SD30, and SS18. These NFA Decision Documents were signed by
the USEPA and ADEC on May 7, 1993. In addition, two of the original ten source areas,
SS63 and SD31, were moved to other OUs based upon their geographic location. Finally,
two other source areas were moved into OU 4. FT23 (the FTA) and SS10 (the ADSA) were
added to OU 4 based on their proximity to the other source areas within the OU. A
summary of the historical changes in source areas associated with OU 4 is presented in Table
2-1.
Currently there are six facilities located within OU 4 which may be designated
as "source areas", including SD24, SD25, SD28, SD29, FT23, and SS10. SD26 and SD27,
while recommended for NFA, are still located within the boundary of OU 4. The ground-
water and soil contamination associated with these two facilities were considered as part of
the overall OU 4 contamination. In keeping with the premise that the contamination associ-
ated with OU 4 was not specifically related to individual hangars, the OU was divided into
two "study areas", OU 4 West and OU 4 East (Figure 1-2).
In accordance with the FFA, an RI of OU 4 was conducted in the summer of
1993. The RI determined the nature and extent of contamination, and the potential risks to
public health and the environment. The results were compiled and analyzed in the RI
Report. The RI concluded that fuel, fuel constituents, and low levels of solvents were found
in soil and groundwater in OU 4. Low levels of semi-volatile constituents and pesticides
were found to be relatively widespread within OU 4 soils. Isolated areas of elevated fuel
constituents were detected in the soils at the location of the leaks or spills. In addition, four
plumes of dissolved fuel constituents and two plumes of dissolved solvents were identified in
the groundwater.
The Final RI/FS was submitted in September, 1994. A Proposed Plan was
distributed to the public on 11 April 1995, and a public meeting to discuss the plan was held
2-4
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Table 2-1
Source Areas at Operable Unit 4
Elmendorf AFB, AK
™S:-^^g^^^K5^^SS«::r:
^^^"Z-*^*^"^^.*^:-*-?.;*
SD24
SD25
SD26
SD27
SD2S •
SD29
SD30
SD31
SD18
SS63
FI23
SS10
li«;"i.-:E-? L' .-i^Sc^ftb'iOi^a^^
~ r .^.^•:^~~~~X?>.~.s.-.;. ;|-£3£=5~-:?
Building 42-400
Building 42-425
Building 43-550
Building 42-300
Building 43-410
Building 43-450
Building 21-900
Building 32-060
Building 22-02 1
Building 52-140
Fire Training Area
Asphalt Dram Storage Area
SKs«sxjrSS£~'^^^?S2Sn.-'»: -'~ ' "•"-
Remains as part of OU 4
Remains as pan of OU 4
No Further Action*
No Further Action*
Remains as pan of OU 4
Remains as part of OU 4
No Further Action
Moved to OU 3
No Further Action
Moved to OU 7
Moved to OU 4 from OU 7
Moved to OU 4 from OU 7
' These taurcc areas, -while recommended for No Farther Action, arc still included within die boundary oCOU 4.
OPTIONAL FOflM 39 (/-TO
2-5
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on 10 May 1995. The index of documents entered into the Administrative Record for OU 4
is provided as Appendix A.
2.3 Role of Response Action
The CERCLA process described above is intended to identify solutions to con-
tamination issues where they exist. The remedial action described hi this Record of Decision
(ROD) addresses threats to human health and the environment posed by contamination at
OU 4. The RI/FS Report defines these threats as both groundwater and soil contaminants.
At this time, soil will be actively treated where the contaminants within the soil pose a
potential future threat to groundwater. Intrinsic remediation will be used for all groundwater
contamination, and for soil contamination where contaminants do not pose a threat to the
groundwater. Groundwater and soil will both be monitored to evaluate the progress of
intrinsic remediation processes. Further response actions, coordinated with the regulatory
agencies, may be considered if monitoring finds unacceptable contaminant migration occurr-
ing, or unacceptable reduction in contaminant concentrations through intrinsic remediation.
2.4 Community Participation
Public participation has been an important component of the CERCLA process
at Elmendorf AFB. Activities aimed at informing and soliciting public input regarding base
environmental programs include:
Environmental Update: Environmental Update is a newsletter distri-
buted to the community and interested parties. It discusses the progress
that has been made on OUs and advises the public about opportunities
to provide input concerning decisions to address contaminated areas of
the base. Aspects of the OU 4 CERCLA progress have been published
in this newsletter.
Community Relations Plan: The base environmental personnel main-
tain and regularly update a Community Relations Plan. It describes
how the base will inform the public of base environmental issues and it
solicits public comment on base environmental programs.
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The Restoration Advisory Board/Technical Review Committee:
Base personnel meet regularly with representatives of the community to
discuss base environmental programs and solicit their comments.
Public Workshops: On 5 February 1992, approximately 75 people
attended a public workshop where base personnel discussed base envi-
ronmental programs and encouraged public participation.
Videotape: Base personnel made a videotape describing base environ-
mental activities. The tape is shown to base employees as well as the
general public.
Speakers Bureau: The 3rd Whig Public Affairs Office maintain; a
speakers bureau capable of providing speakers versed in a variety of
environmental subjects to military and civic groups.
Newspaper Releases: News releases are published on significant
events during the ERP. News releases are made announcing all public
meetings that arc held to discuss proposed remedial actions.
Information Repositories: Public access to technical documents is
provided through information repositories located-at the Bureau of Land
Management's Alaska Resources Library and the University of Alaska
at Anchorage's Consortium Library. The information in the reposi-
tories is also maintained in the administrative record. The remedial
action was selected based on the information held in the administrative
record.
Display Board: During public functions, a display board, showing key
elements and progress of the Elmendorf IRP, is used to communicate
technical issues to the public. It is used during both on-base and off-
base events.
Proposed Plan: The OU 4 Proposed Plan was distributed to the public
on 11 April 1995, a public meeting was held 10 May 1995, and the
public review period was from 11 April to 12 May 1995. Comments
from the public are contained in Part III. Responsiveness Summary of
this document.
Public Notice: Public notices have been issued prior to all significant
decision points in the ERP. For OU 4, public notice was issued for the
Proposed Plan in the Anchorage Daily News (4/9/95) and the Sour-
dough Sentinel (4/6/95).
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Mailing List: A mailing list of parties interested in the restoration pro-
gram is maintained by the base. Notices and publications (news
releases including the OU 4 Proposed Plan meeting) are released via
the mailing list.
Responsiveness Summary: Public comments were received on the OU
4 Proposed Plan. The USAF maintains a record of all comments and
has published responses to the comments in this Record of Decision.
All decisions made for OU 4 were based on information contained in the Administrative
Record. An index to the documents contained in the Administrative Record for OU 4 is
provided as Appendix A.
2-8
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3.0 SITE CONTAMINATION, RISKS, AND AREAS REQUIRING
RESPONSE ACTIONS
This section identifies the areas which were investigated, and those that require
remedial action. These areas were chosen based on the risk that contaminants pose to human
health and the environment. The basis of this analysis is the data collected during the
Remedial Investigation (RI) which identified the nature and extent of contamination in QU 4.
3.1 Nature and Extent of
The contamination present at OU 4 is associated with contaminant transport in
the vadose zone, dissolved aqueous transport, and volatilization. These processes are briefly
discussed below.
Vadose Contaminant Transport: Before releases could be detected or
remediated, fuel constituents such as benzene, or solvents such as trichloroethene (TCE)
migrated from the source to the water table through the vadose zone. A schematic of the
principal transport mechanisms, including vadose zone migration is shown on Figure 3-1.
Understanding transport is important because the contaminants and risks are not always
associated with the source area, but with the area where an exposure is possible. The risk
assessment considered the current and future transport of contaminants to potential receptors.
Dissolved aqueous transport: Once contaminants have reached die water
table, the principal transport mechanism of solvents and fuels contamination is by aqueous
solution in groundwater. Contaminants can dissolve into solution when water passes over
contaminated soil. Likewise, as contaminated water migrates, it can deposit contaminants on
the soil through which it passes.
Volatilization: Contaminants, such as halogenated volatile organic compounds
(HVOCs) and lighter fuel constituents, can become gases, either volatilizing into the soil or
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I
Juglllv* Ouil
Ctnirollon
Elmenaorf Moraine
ELMENDORF AFB
LEGEND
?U1 Residual Contamination
Dissolved Phase
Contaminants
Nel To Scull
Figure 3-1. A Schematic of Principal Transort Mechanisms in Operable Unit 4,
. AK
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directly to the atmosphere. Concentrations of volatile organic compounds in soil gas in some
locations such as at the FT A and Hangar 11, were detected at elevated concentrations (> 100
ppmv) indicating that volatilization of these constituents is occurring.
During the RI, samples of soil and groundwater were collected and analyzed
for organic and inorganic constituents. Significant levels of organic contaminants were
detected hi the soil and groundwater. These contaminants include fuel products such as
benzene, halogenated volatile organic compounds such as TCE, and semi-volatile organic
compounds (SVOCs) such as naphthalene. Other contaminants include inorganic compounds
such as selenium and pesticides such as alpha-BHC.
To evaluate the nature and extent of contamination and assess risk at OU 4,
the OU was divided into two study areas, OU 4 East and West, and further divided into
several smaller areas: the FTA, Hangar 11, Hangar 14, Hangar 8, Hangar 10, Hangar
15/Building 43-410, and the ADSA. Tables referenced below list the frequency of occurr-
ence, and maximum concentrations of all constituents which were statistically established as
contaminants of potential concern (COPC) during the RI hi soil and groundwater.
A detailed discussion of the determination of COPC is included in the OU 4
RI/FS Report (USAF, 1994). In summary, COPC were determined by statistically com-
paring site analytical results with background/upgradient results available for the same
constituents. Chemicals retained as COPC are those which were measured on-site at concen-
trations significantly elevated above background/upgradient concentrations of the same
chemicals. Once COPC were statistically established, the list was further refined by
removing affected analytes associated with analytical methods that were determined to be
non-representative of site conditions, and analytes which had results that were all below
instrument-specific detection limits and were not second-column confirmed. The refined list
of COPC was then subjected to a risk-based screening procedure during which maximum
analyte concentrations were compared with risk-based concentrations associated with: a) a
systemic hazard quotient of 0.1; b) a lifetime incremental cancer risk of 10 * for water; and
3-3
-------
c) a lifetime incremental cancer risk of 10 "7 for soil. This risk-based screen helped to
produce a list of COPC which were most likely to contribute significantly to the risks
associated with OU 4. Mixtures of chemical compounds cannot be assessed in a risk
evaluation, so gasoline, diesel, and kerosene did not undergo the rigorous statistical eval-
uations made on the individual compounds.
The OU 4 data summary tables are provided by area. The tables do not
include results below the detection limit. The Maximum Contaminant Levels (MCLs) for
groundwater, and the Alaska Cleanup Matrix (ACM) guidelines for soil, are also listed on
the tables for all COPC. Figures depicting the locations of all soil and groundwater contami-
nant occurrences in excess of potential cleanup levels are included where applicable.
3.1.1 Groundwater
Groundwater contamination is discussed based upon contaminant "plumes"
delineated during the RJ. A total of six groundwater contaminant plumes were identified at
OU 4. All plumes are approximated, and are depicted based upon contaminant concentra-
tions greater than 5 /ig/L, which coincides with the MCL for commonly occurring
constituents such as benzene and trichloroethene. The six groundwater plumes are shown on
Figure 3-2.
OU 4 West
Five groundwater plume areas were identified in the OU 4 West study area;
one each at Hangar 14, Hangar 11, and at the Hangar 8/10 area, and two plumes at the
FTA. Contaminants of concern for groundwater hi OU 4 West include fuels, non-
halogenated organic compounds (NHVOCs), HVOCs, and pesticides. Metals were also
detected in the groundwater at OU 4 West. However, a comparison to background metals
concentrations was conducted. Background metals concentrations hi groundwater were
collected by the USGS in the Anchorage Bowl area and compiled in the Elmendorf Air
3-4
-------
Hangar 15
Building 43-410
Asphalt Drum
Storage Area
Davis Highway
c^^ East/West Apron
Figure 3-2. Location of OU 4 Groundwater Contaminant Plumes,
ElmendorfAFB,AK
-------
Force Base, Alaska, Basewide Background Sampling Report (USAF, 1993). These metals
data have been used historically at Elmendorf AFB for comparison with on-site groundwater
metals concentrations. Confidence intervals of the USGS data mean for a given metal were
compared with confidence.intervals for the OU 4 analytical results for the same analyte. If
the confidence intervals of the two means overlapped, the two means were considered not to
be different and the particular metal was removed from consideration as a COPC. Based on
this evaluation, all metals in groundwater at OU 4 West were determined to be at background
concentrations. The USGS upper confidence limit concentrations used for the comparisons
are the following for the metals in question:
Antimony: 0.004 jt/L
Arsenic: 0.042/xg/L
Iron: 129.83 jig/L
Manganese: 12.917 /*g/L
Two plumes were identified at the FTA, including an HVOC plume and an
NHVOC plume. The main contaminant hi the HVOC plume is trichloroethene, while
benzene and ethylbenzene are of primary interest hi the NHVOC plume. Groundwater
analytical data for all FTA COPC are summarized in Table 3-1. The two plumes, which are
drawn based upon constituents which exceeded groundwater cleanup levels, are depicted hi
Figure 3-3. The HVOC plume was detected emanating from the southern portion of the
FTA, extending roughly parallel to the direction of groundwater flow. The configuration of
the plume as drawn-is approximately 750 feet by 2000 feet. The NHVOC plume roughly
parallels the HVOC plume (Figure 3-3), and has approximate dimensions of 800 feet by 35
feet.
At the FTA, seven compounds exceeded the MCLs. Contaminants that
exceeded MCLs and their ynayjmum detected concentrations include: 1,1,1-trichloroethane
(TCA), 242 /ig/L; 1,1-dichloroethene (1,1-DCE), 13.7 /zg/L; 1,2-dichloroethane (1,2-
DCA), 12.1 Mg/L; tetrachloroethene (PCE), 77.8 Aig/L; trichloroethene (TCE), 74.7 ^g/L;
1,2-dichloroethene (1,2-DCE), 741 /zg/L; and benzene, 398 pg/L. Probable sources for
-------
Table 3-1
Fire Training Area Organic* Groundwater Results for Contaminants of Potential Concern
Elmendorf AFB, AK
* % % <
SS ^S •, •*' % ss \% s •• s% ' •• f"~ % *"
0 *" ^ v s •!" X^ ^ <•• •> ^ *• ^ *• v" %% s 5 X s
IIS!
^; ftfatithdm ..
Indicator Parameters
SW80l5MP(Mg/L)
SW80I5ME (Mg/L)
Unknown compounds within Gasoline range
Unknown compounds within Diesel range
Unknown compounds within Jet Fuel range
-•
••
23900 1
224!
56101
9/9
8/8
15/15
FP56
FP52
FP52
Contaminant Parameters
SW80IO (Mg/L)
SW80I5ME (Mg/L)
SW80I5MP (Mg/L)
SW8080 (Mg/L)
SW8240 (Mg/L)
l.l.t-Trlchloroelhane
1,1,2-Trichloroelhane
I.l-Dlchloroethane
I.l-Dichloroethene
1 ,2-Dlchlorobenzene
1.2-Dlchloroethane
1.3-Dlchlorobenzene
1.4-Dichlorobenzene
Chloroethanc
Chloroform
Chloromelhane
Telrachloroethenc
Trlchloroelhene
Trlchlorofluoromethane
Vinyl Chloride
els- 1 .2-Dlchloroelhene
cl>-l ,3-Dlchtoropropene
trans- 1,2-Dlchlototlhene
Diesel
Benzene
Ethvlbenzene
Toluene
Xvlene (total)
della-BIIC
I.l.l-Trlchloroethane
200
5
--
7
600
5
600
75
-•
100
"
5
5
-
2
70
••
100
--
5
700
1,000
10.000
-
. 200
242_
1.17 T
84.1
13.7 T
2.62 T
12.4 T
0.557 T
1.96 T
1.9
1.29 HT
2.32 T
2L8_
74.7
0.379 T
O.I2S TH
2!L_
0.0969
0.668 T
2920
398
448_
327
1380
0.0276 PH
156
20/24
3/24
18/24
4/24
3/24
»l/24
2/24
2/24
1/24
4/24
4/24
17/24
20/24
2/24
1/24
16/24
1/24
2/24
2/24
24/26
26/26
23/26
26/26
2/6
. 6/6
FP56
FP56
FP56
OU4W-II
OU4W-1 1
FP56
FPJ2
OU4W-1 1
OU4W-6
OW-5A
FP56
OU4W-II
FPS6
OU4W-II
OU4W-II
OU4W-II
OU4W-9
OU4W-II
FP56
FP36
FP52
OU4W-II
OU4W-1 1
FP52
FP56
I
-J
-------
Table 3-1
(Continued)
MetW ^
SW8240 (|ig/L)
SW8270 (ng/L)
,- -i- - - " - ' -" >" --
' \ * t - ; -»*v ^v% * *** **i'*'
^ v.: '^vWti^&^&e'w.
1,1-Dichloroelhane
1,1-Dtchloroelhene
1 ,2-Dichloroelhane
Acetone
Benzene
Ethylb'cnzene
Mela-ftPara-Xylene
Methyl ethyl ketone
Ortho-Xylcne
Tclrachloroelhene
Toluene
Trichloroeihene
cis-l,2-Dichloroelhene
1,2-Dlchlorobenzene
1.3-Dichlorobenzene
1 ,4-Dlchlorobenzene
2-Melhylnaphllialene
2-Methylphenol (o-cresol)
4-Methylphenol (p-ctesol)
Acenaphlhcne
Benzole acid
Fluorene
Napthalene
Phenol
«
7
5
••
5
700
10,000+
--
10,000+
5
1,000
5
70
600
600
75
--
"
--
-
--
-
--
70.7
8.06
12.1
112 H
325
351
888
27.7 H
146
13.6
261
63
39.7
1.36
0.391
0.875
48.2
2.13
40.6 F
0.362
7.98 L
0.386
S8.3
5.12 L
6/6
2/6
4/6
2/6
6/6
6/6
6/6
1/6
6/6
5/6
6/6
6/6
3/6
3/24
1/24
2/24
12/24
6/24
9/24
1/24
1/24
2/24
15/24
6/24
.. :M««tJpnof
XjUntttyM 4
j^ftl&Mftlltt '1
FP56
FP56
FP56
FP52
FP56
FP52
FP52
FP52
FP52
FP52
FP56
FPS6
FP56
OU4W-II
FP52
OU4W-II
FP52
FP52
FP52
FPS2
FP52
FP52
FP52
FP52
o
o
F = Elutiou with a similar analyle is suspected.
H = Result given is suspected to be biased as much as 50% high.
I •=• Unknown compounds (that are likely the result of decomposition of fuel or arochlor products, or naturally occurring organic matter), quantified as Hie listed components.
L = Result may be biased up to 50% low based on QA/QC indicators.
P = Presence of analyle is confirmed; however, concentration was not confirmed, concentration listed is a conservative estimate.
T = No confirmational analysis was performed.
Underline indicates preferred result when multiple analytical methods were performed for a single constituent.
• No inorganic COPCs identified for groundwater at (his location.
MCL = Maximum Contaminant Level.
value is the MCL listed for "Xylencs."
-------
ELMENDORF AFB
LEGEND
Well Location
Direction of Groundwater
Movement in Shallow Aquifer
Source Areas
North
OU4W-17
Approimate Location of
Underground Storage Tank
Estimated Analytical Data
HVOC Plume (>5 /*g/L)
Estimated Analytical Data
NHVOC Plume (>5 ug/L)
SCALE
0 200 400
Surface Fire Training Stand
Former
Underground Storage Tank
OlUW-13
Fire Training Pit (Bermed)
FP-55
OU4W-15(SB-S3)
- OU4W-7(SB-S6)
,OU4W-16
Figure 3-3. Fire Training Area Groundwater Contaminant Plume,
Elmendorf AFB,AK
3-9
-------
groundwater contamination at FTA include the fire training pit, the surface fire training
stand, and a former 22,000-gallon underground storage tank that has been removed.
In the Hangar 14 vicinity, one groundwater plume, approximately 300 feet by
150 feet, composed of benzene was detected. No other fuel-related constituents were iden-
tified in this plume (Table 3-2). The plume is located approximately 500 feet southwest of
the Hangar (Figure 3-4). Benzene (207 /xg/L) was the only constituent exceeding MCLs in
this plume. No specific source for the groundwater contamination was identified at
Hangar 14.
At Hangar 11, an NHVOC groundwater plume was identified based upon
groundwater analytical data (Table 3-3). The plume is located immediately south of Bums
Road, and as drawn, is approximately 200 feet wide (Figure 3-5). While the downgradient
edge of contamination in this plume was not defined during the RI, several uncontaminated
wells are located approximately 1000 feet downgradient of the plume. Three constituents
were detected in levels above MCLs, including benzene (2,600 jig/L), ethylbenzene (1,360
/ig/L), and toluene (5,590 pg/L). Two sources of contamination were identified: the valve
pit located west of Hangar 11, and underground storage tanks located southwest of the
Hangar. The valve pit has been taken out of service and the three USTs formerly served by
lines connected to this valve pit have been removed.
The Hangar 8/10 area groundwater plume is composed of fuel-related
compounds. The plume extends from Hangar 10 to several hundred feet southeast of Hangar
8. The plume roughly parallels groundwater flow, and as depicted, has dimensions of
approximately 1200 feet by 700 feet (Figure 3-6). Benzene (266 ngfL) was the only
compound detected that exceeded MCLs at this location (Table 3-4). The probable source of
this plume is Pumphouse 2 and/or the associated piping in the vicinity of the pumphouse.
All lines associated with fuel facilities in the vicinity of Pumphouse 2 have been tested and
all leaks have been repaired. In addition, all base USTs are being upgraded to meet current
standards.
vio
-------
Table 3-2
Hangar 14 Benzene Plume Area Organic and Inorganic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK
Mettttjd
' ' "
s" - s- , . ' \ '-' " V
,\<, ,< "^ ' Ah«ij?<* * V ''-$. 5
^lWi.«i-.i»friPt«)i'''-
H ,;,M«
-------
OU4W-6 (SB-29)
OU4W-14 (NH-20)
OU4W-7 (SB-36)
ELMENDORF AFB
LEGEND
W.ll Location
Csllmatad B»ni«n»
Plum* (>5*40/L)
Direction ol Croundwatcr
Mov«m«nl In Shallow
AqulUr '
SCALE
100 200 300
Figure 3-4. Hangar 14 Area Groumlwater Contaminant Plume,
Elmendorf AFI \K
-------
Table 3-3
Hangar 11 Plume Area Organic* Groundwater Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
4
% , -Awstyfe >,,^% "-, '• ; ,"„
- ',> + \ •. t > , ^
-, -' -\ "-?' , x« <^\
^li^fifHdkv
>*$$ti^4tw;
^ ;Laplf
-------
ELMENDORF AFB
LEGEND
Well Location
C *) Estimated VOC Plume
*••••«•* . _ ,. \
Valve Pits
OU4W-8
Underground
Storage Tanks
Probable Source Areas
Direction of Groundwater
Movement In Shallow
Aquifer
52WL03
^
52WL02
Figure 3-5. Hangar 11 Area Groundwater Contaminant Plume,
-------
ELMENDORF AFB
LEGEND
Estimated VQC Plume
Mg/L)
Probable Source Areas
Direction of Croundwoier
Movement in Shallow
AquHer
Figure 3-6. Hangar 8/10 Area Groundwater Contaminant Plume,
Elmendorf AFB, AK
3-15
-------
Table 3-4
Hangar 8/10 Plume Area Organic'
Groundwater Results for Contaminants of Potential Concern
Elmendorf AFB, AK
M«hb' * *° % \ ^ V
-------
OU4£ast
In the OU 4 East study area, one groundwater contaminant plume was identi-
fied based upon groundwater analytical results in the Hangar 15/Building 43-410 area. The
ADSA was evaluated for groundwater contamination, .however no significant contamination
was identified. Compounds of concern identified in OU 4 East include HVOCs and
NHVOCs. Although metals were detected in groundwater at OU 4 East, no constituents
exceeded background levels except aluminum in the Hangar 15/Building 43-410 area. For
aluminum, there was insufficient background data available to make a comparison.
An HVOC plume was delineated near Hangar IS trending east-west
(Figure 3-7). An isolated NHVOC plume, located south of Building 43-410, was also identi-
fied during groundwater screening, however mis plume was not confirmed through laboratory
analytical testing. The HVOC plume is characterized by low levels (< 25 itgfL) of TCE and
PCE. These were the only two constituents found at concentrations above MCLs
(Table 3-5), at concentrations of 19.5 /ag/L and 23 fig/L, respectively. Probable sources of
contamination for the HVOC plume include a dry well located immediately east of Hangar
15, and a leach field located farther east of the Hangar. The probable sources for the
NHVOC plume identified during groundwater screening include valve pits and fuel lines in
the area. All fuel lines in the area have been tested and all leaks have been repaired.
At the ADSA, several NHVOCs, including ethylbenzene, total xylenes, and
unknown compounds hi the diesel range, were detected at low concentrations. The analytical
results for COPC from this area are presented with those of the Hangar 15/Building 43-410
area hi Table 3-5. No COPC from the ADSA were detected at levels above MCLs.
3-17
-------
ELMENDORF AFB
LEGEND
Well Location
Hydropunch Location
Analytical Data HVOC Plume
Probable Source Areas
Screening Data NHVOC Plume
Direction of Groundwater
Movement in Shallow
Aquifer
Figure 3-7. Hangar 15/Building 43-410 Area Groundwater Plume,
Elmendorf AFB, AK
3-18
-------
Table 3-5
Hangar 15/Building 43-410 Plume Area Organic Groundwater Results for Contaminants
of Potential Concern, Elmendorf AFB, AK
M"^ ' / ^"Y - - -^ ' V£X
<^V, Afl&WL,- ^^VM
rs
1,1,1-Trlchloroetliane
Chloroform
Chloromethane
Tetrachloroethene
Trichloroethene
cis-l,2-Dichloroelhene
Glhylbenzene
Toluene
Xylene (total)
Nitrate-Nitrite as N
Aluminum
? r^!::^^
* •>• •". N '%^ % ' % s
200
100
-•
5
5
70
700
1,000
10,000
10,000
0.2 to 0.5 '
2.22
2.72
11.7
I9.S
23
0.853
1.7
2.0S
3.28
7.07
O.S87
^dfr%iM<^y , ^
1/15
14/15
4/15
3/15
3/15
3/15
12/15
14/15
12/15
15/15
13/15
<"^toB$io
-------
3.1.2 Soils
Soil data from OU 4 was evaluated by area based upon surface and subsurface
contaminant occurrences. Surface soils include all soils above five feet. Subsurface soils are
those below five feet. Results below the detection limits are not included in the analytical
summary tables.
OU 4 West
The contaminants of concern in soil at OU 4 West are primarily fuel-related,
including NHVOCs, SVOCs, and pesticides. Contamination at the FTA includes NHVOCs,
SVOCs, kerosene and diesel in the shallow soil. Subsurface contamination was primarily
fuel-related. Tables 3-6 and 3-7 list the sample depth, maximum concentration, locations,
and levels associated with the Alaska Cleanup Matrix for non-UST soil (ACM) for all COPC
in the surface, and subsurface soil samples at the FTA.
Metals and pesticides were also identified. Metals were detected at or near
background concentrations. Background soil analytical data were collected in association
with the basewide background sampling effort (USAF, 1993). During the background soil
investigation, 60 soil samples were collected from 14 soil borings drilled at background
locations at the base. The analytical results associated with these samples were pooled into
surface and subsurface soil results, and were used as the basis to conduct statistical
comparisons with on-site results. There are also no known anthropogenic sources for the
majority of the metals detected.
Only one constituent was identified in the surface soils at levels above the
Alaska Cleanup Matrix for Non-UST soil (ACM): kerosene (2,200 mg/kg). This non-spec-
iated result does not appear as a COPC in Table 3-6, since these results cannot be used in the
evaluation of risk. Two constituents, benzene (715 mg/kg), and gasoline (3,710 mg/kg) were
identified exceeding the ACM in the subsurface soil. These results do not appear in
3-20
-------
Table 3-6
Fire Training Area Organic and Inorganic Surface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Mtttwd *
\'- \^( -^ £ * , v" }^
-^^J^^'l^rfe
-- - , -\ "v. , ,
" \\%'\V v"\\>^-
' '•••• i:~i:i •• ^ v 1\
y ..---A i.AH -.. jfi\
V ^'3^S^^^1*V
>. * -i>C ~"'v ^ ' ^ £ s ^
*SN\ « V %s ' -
^^K^tr
ronlaminant Parameters
SW80I5MP (ME/kg)
SW8080 (Mg/kg)
SW8240 (Mg/kg)
Benzene
•Ihylbenzene
Toluene
Xvlene (total)
BTEX
4.4'-DDD
4,4'-DDE
4.4'-DDT
Aldrln
Endosulfan sulfale
Endrln
Heplachlor
PCD- 1260
alpha-BHC
beia-BHC
gamma-BHC (Llndane)
Meta-A Para-Xylene
Methylene chloride
Ortho-Xylene
2-Methylnaphlhalenc
Acenaphthene
Accnaphthylene
Anthracene
Benzo(a)anthracene
Denzo(a)pyrene
Benzo(b)fluoranlhene
Benzo(g,h,i)pcrylene
Benzo(k)l1uoranlhene
Chrysene
Dlbenz(a.h)anthracene
500
--
••
-
100,000
"
.
•-
-•
"
--
••
•--
••
-•
1,000,000
•-
1.000.000
--
•
-•
--
--
--
--
.
"
••
..
--
-
••
--
-
«
••
-•
"
--
«
-
«
•-
•-
"
--
•;
"
-
-
-
--
--
.
--
.
••
.
•-
S3.I
2800
1480
8310
12,590
13.9
2.92
38.5
4.55
4.23
14.8
2.84
151
0.836
7.02
0.724 PH .
54.1
19.8 H
. 610
0.454
1.07
0.021
2.2
2.18.
2.21
4.72 F
0.894
4.72 F
2.44
0.54
2/5
2/5
4/5
5/5
5/5
4/6
2/6
3/6
2/6
2/6
1/6
1/6
1/6
2/6
2/6
2/6
1/5
3/5
1/5
6/11
4/11
l/ll
5/11
6/11
6/11
6/11
5/1 1
6/11
7/11
4/11
SD-21
SS-19
SS-19
SS-19
SS-19
SS-18
SB-13
SB- 13
SS-18
SS-20
SB-21
SD-21
SB-23
SS-19
SS-18
SB-13
SS-19
SS-18
SS-19
SB-24
SB- 14
SB-22
SB- 14
SD-14
SB-20
SB-20
SB- 14
SB-20
SB- 14
.SIM 4
-------
Table 3-6
{Continued)
, .. / „
^ V ^ X MWWPI ^ •. j $ J'*
SW8240 (Mg/kg) (cont'd)
SW8280 (Mg/kg)
Indicator Parameters
SW60IO (mg/kg)
Contaminant Parameters
SW6010 (mg/kg)
SW742I (mg/kg)
SW90I2 (mg/kg)
*\-\V- "*vV, V
''- J ^ ^^ifc&/l?^' '"^
•swjliv ?>4 jjp^ v' WBw.i*' $ ^ .«***•
Dibenzofliran
Dibulylphthalate
Fluoranthene
Fluorene
lndeho(l,2,3-cd)pyrene
Naphthalene
Phenanlhrene
Pyrene
bls(2-Elhylhexyl)phthalate
OCDD
Calcium
Copper
Magnesium
Manganese
Potassium
Chromium
Cobalt
Lead
Molybdenum
Nickel
Selenium
Zinc
Lead
Cyanide
;V<2^;1
x^^'*'*3iilll^
•feaw^y^.JrjyplslRllIll^
-
«
•
-
-•
--
«
-
--
--
•-
--
-
••
~
--
••
•-
--
--
-•
--
--
••
-
--
.
••
• •-
--
--
•-
--
-•
8,013.23
31.67
10,904.10
929.98
845.75
48.44
19.52
10.69,
~
50.68
0.54
90.01
10.69
--
^^^I^^V ;1>'
^wSl'i'iisl?Pfl
p.668
0.051
4.74
0.735
0.897
0.624
5.81
4.52
I.I7H
0.683
9330
1120
11900
1820
1560
54
31
58.3
2.26
71.6
16.2
641
68.8
0.316 H
ifSSC-
H Wrallm^
^^?sS iMsi'fJSff^?'*'^^
4/11
l/ll
6/11
4/11
S/ll
5/11
5/11
7/11
5/11
l/ll
ll/ll
ll/ll
ll/ll
11/11
ll/ll
ll/ll
ll/ll
ll/ll
ll/ll
ll/ll
7/11
I.I/I 1
ll/ll
l/ll
^:*&*t ,
Jl* "Itfl^a^."
Xj; J^^lf'll'raMttn'^ ••
SB-14
SB-22
SB-14
SB-14
SB-14
SB-14
SB-14
SB-14
SS-19
SB-24
SB-14
SB-23
SB-14
SB-14
SB-14
SO- 14
SB-14
SB-22
SD-22
SB-14
SB-14
SB-23
SB-22
55-18
F •= Co-elution witli a similar analyle is suspected.
H = Result given is suspected to be biased as much as 50% high.
P <° Presence of analyle Is confirmed, however, concentration was not confirmed, concentration listed Is a conservative estimate.
Underline indicates (lie preferred result when multiple analytical methods were performed for a single constituent.
OCDD = Oclachlorodibenzodioxin •
laska Cleanup Matrix for Non-UST Soil.
-------
Table 3-7
Fire Training Area Organic and Inorganic Subsurface Soil Results for
Contaminants of Potential Concern
Elmendorf AFB, AK
Mdhdd
Indicator Parameters
SW8080 (Mgftg)
Contaminant Parameters
SW80I5MP (|ig/kg)
SW8080 (Mg/kg)
SW8240 o^>y"^% £ \- ;
4L/' V^WH^ : ^%^
PCn- 1260
Benzene
Elhvlbenzene
Toluene
Xvlene (total)
BTEX
alpha-DHC
bela-BHC
1,1,1-Ttlclilotoethane
Acetone
Denzene
Ethylbenzene
Mela-APara-Xylene
Methyl ethyl ketone
Melhylene chloride
Ortho-Xylene
Telrachloroelhenc
Toluene
Ttichlorocllienc
els- 1 ,2-Dlchtotoelhene
^ '.:.'- C -'.t^
•.f\-. ^ -. "" ^ "•'•'' •- •.•*
'/v vx'&fclVi* \,">>
*W+*"? ^"At,-. Vs
•. f-.. v. ' x •> <-\;x* ••*«/'
--
500
--
--
-•
100.000
••
--
--
500
1,000,000
1,000,000
--
"
1.000,000
••
1,000,000
-•
--,
> ^-. /\ i.-; •?-. s-*V
%% -.^ •.<•.' ' Si ••>
•• i^x-^ X> "i* i ^ <•'•.'
Jwk|roii(nd::up|j«r J
•.:; VTjsie-r-ant* M"«lt:x:;':;:
•^C^Jo11 ^ 5^ J *•"**??
v^^u 4C\<.> 'St.^A*^
-
--
--
'
-- •
--
•-
--
.
•
..
•-
-
--
••
-
-•
--
--
.". '" •• ^ S1^- '•' s "
13.4 1
IIP
10600
6360 P
S5700
67,868.5
0.373 H
5.69
2.92
378
47.1
87$
5840
197
91.5
2810
6.88
293
36.4
19.2
^^ffrequ^^l t,;
*;•. •.Jww|tt> \ 5
'A\ /% •• ?3^ ^*
-^kWJP*11^ -;v
1/12
6/25
10/25
21/25
17/25
21/25
2/12
4/12
1/25
4/25
4/25
5/25
5/25
11/25
18/25
5/25
2/25
5/25
3/25
2/25
" t&b s *
•jxdrMjtimurti -
;^^^N: •-
SB-18
SB-19
SD-24
SB-19
SB-24
SB-24
SB-13
SB-18
SB-22
SB-19
SB-22
SB-19
SB-19
SB-19
SB-22
SB-19
SB-22
SO- 19
SB-22
SB-24
to
-------
Table 3-7
(Continued)
Melhotl
SW8270 (tug/kg)
U)
2-Melhylnaphthalene
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)nuoranthene
Chryscne
Dibenz(a,h)anthracene
Dibenzofntan
Fluoranthene
Fluorene
lndeno(l ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
6.2
0.0594
0.208
0.69
0.946
1.91 F
0.234
1.91 F
0.908
0.14
0.0653
1,75
0.084
0.313
3.21
1.23
1.59
6/27
2/27
3/27
3/27
3/27
3/27
3/27
3/27
3/27
2/27
2/27
3/27
4/27
3/27
S/27
3/27
3/27
SB-22
SB-20
SB-20
SB-20
SB-20
SB-20
SB-20
SB-20
SB-20
SR-20
SB- 18
SB-20
SB-20
SB-20
SB-22
SB-20
SB-20
Indicator Parameters
SW60IO (mg/kg)
Aluminum
Calcium
Copper
18,116.77
10,264.39
59.84
18200
16400
493
27/27
27/27
27/27
SB-22
SB-24
SB-18
-------
Table 3-7
(Continued)
Method
\
Anilyte
Adi*
•. \
- Background tfpptr
T<»l*t4ttte Ottiilt
j.1* A ^ "* ^ %
Mtarfrmuft. ,
Vs dtutied """•
' C8&eair
-------
Table 3-7, since the benzene result was below the detection limit for that analysis, and the
gasoline result represents a non-speciated compound. The locations of areas where soil con-
centrations exceeded the ACM are depicted on Figure 3-8.
Migration of contaminants into the subsurface is thought to be almost vertical
due to the coarse, porous nature of the FTA soils. Deep soil contamination may act as a
continuing source of contamination to groundwater. Contaminated soil zones above the
water table represent a "smear zone" of contamination, resulting from fuel and solvent
constituents that migrated to a higher water table and were left in the vadose zone when the
water table receded. The principal sources of contamination at FTA include residual fuels
spread on the ground for fire training exercises, fuel supply lines to the training pit, and a
former 22,000-gallon underground storage tank. Drums suspected to have been buried hi the
southern portion of a construction rubble pile east of the FTA, may also be a source of
contamination. The underground storage tank has been removed, and the FTA is no longer
used.
At Hangar 14, none of the surface or subsurface soil samples had analytical
results exceeding the ACM. Tables 3-8 and 3-9 summarize the maximum concentrations,
locations, and frequency of occurrence, of surface and subsurface analytical results. The low
levels of soil contamination detected show no obvious trends, indicating contaminant sources
to be incidental contamination via paving, vehicular traffic, or air traffic residue.
Contamination was detected in numerous surface and subsurface soil samples
in the Hangar 10/11 area (Tables 3-10 and 3-11). Contaminants include low levels of
SVOCs, NHVOCs, pesticides, and metals. Metals were determined to be the result of
background conditions. Contaminant levels exceeded cleanup levels only in the subsurface
soils.
Two constituents were identified with concentrations exceeding the ACM in
the subsurface soils: Diesel Range Organics (DRO), at 5,900 mg/kg, and Gasoline Range
Organics (GRO), at 4,100 mg/kg. These results do not appear in Table 3-11, since they are
3-26
-------
ELMENDORF AFB
LEGEND
A Soil Boring Location
Surface Soil Location
SB-20
Fire and Rescue
Training Area
Surface Contamination
(Less than 5 ft.)
Subsurface Contamination
(Greater than 5 ft.)
Surface and Subsurface
Contamination
FORMER UST
Figure 3-8. Location of Soil ACM Exceedances at the Fire Training Area,
Elmendorf AFB, AK
-------
Table 3-8
Hangar 14 Organic and Inorganic Surface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
Contaminant Parameters
SW8080 (Mg/kg)
SW8270 (mg/kg)
Indicator Parameters
SW6010 (mg/kg)
Analyte
4,4'-DDD
4,4'-DDE
4.4'-DDT
Aldrin
gamma-BHC (Lindane)
Acenaphthene
Anthracene
Benzo(a)antliracene
Benzo(a)pyrene
Denzo(b)fluoranthene
Benzo(k)f1uoranthene
Butylbenzylphthalate
Chrysene
Fluoranthene
Phenanlhrene
Pyrene
Calcium
Copper
Magnesium
Potassium
ACM*
--
--
--
--
--
--
--
-
--
--
.
--
--
--
--
--
--
--
--
--
$adi|K>wtf Upper
ToUrant* Limit
--
--
--
--
--
--
--
-•
--
--
-- •
"
--
--
--
--
8,013.23
31.67
10,904.10
845.75
Maximum \ v ;
»*lttt«
-------
Table 3-8
(Continued)
Method
%
Contaminant Parameters
SW60IO (mg/kg)
SW742I (mg/kg)
Chromium
Lead
Molybdenum
Nickel
Selenium
Zinc
Lead
• VJ;
V v^X '•''''
-
-
-
-
-
-
-
48.44
10.69
--
50.68
0.54
90.01
10.69
Maximum
frequency of -
•detection •.
-
-------
Table 3-9
Hangar 14 Organic and Inorganic Subsurface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
+.
*Ailalyte
^ACRl ->
> <.
Sfttkgwuttd. Upper
tflii&ttter Limit
Maxiiqum -
fatftCtftd
COnMiatiniton
Fftquenty Of
Detection
{trial Ms/
total Salttplteft
Location
of Maximum
Cdntentratitm
Conlaminanl Parameters
SW80I5MP (Mg/kg)
SW8080 (Mg/kg)
SW8240 (Mg/kg)
SW8270 (mg/kg)
Benzene
Xylene (total)
BTEX
4,4 '-ODD
4,4'-DDE
4,4'-DDT
Aldrin
Endosulfan sulfate
Heplachlor
beta-BHC
gamma-BHC (Lindane)
Methylene chloride
Acenaphthene
Anthracene
Bcnzo(a)anthracene
Benzo(a)pyrene
Benzo(b)(1uoranthene
Benzo(g,h,i)perylene
Uenzo(k)fluoranlhene
Butylbenzylphthalate
Chrysene
Dibenz(a,h)antlitacene
Dibutylphlhalate
Fluoranthene
Fluorene
Indeno( 1 ,2,3-cd)pyrene
1'henanlhrcne
Pyrene
500
--
100,000
--
--
--
--
--
--
--
--
--
• . --
-- .
"
--
--
"
--
--
-
--
--
--
--
•-
--
--
--
--
--
--
..
--
•-
--
--
--
--
--
--
--
«
-- .
,--
--
•-
.
--
--
• --
--
--
--
--
16.3 H
59.5 H
96.6
3.97
1.35
8.49
5.93
5.05
0.26 B
1.53 P
2.51
31.5
0.0811
0.156
0.335
0.291
0.525 F
0.196
0.525 F
0.483
0.394
0.0839
0.0162
0.696
0.0482
0.19
0.484
0.707
2/15
6/15
6/15
3/10
2/10
4/10
1/10
2/10
1/10
2/10
2/10
12/15
2/16
1/16
3/16
3/16
3/16
2/16
3/16
1/16
3/16
1/16
1/16
3/16
1/16
2/16
3/16
3/16
SB-36
SB-36
SB-36
SB-S3
SB-53
SB-53
SB-40
SB-40
SB-29
SB-40
SB-40
SB-29
SB-53
SB-53
SB-53
SB-53
SB-53
SB-53
SB-53
SB-40
SB-53
SB-53
SB-40
SB-53
SB-53
SB-53
SB-53
SB-53
U)
o
-------
Table 3-9
(Continued)
Method
Indicator Parameters
SW60IO (mg/kg)
Analyte
.:-*4
Aluminum
Calcium
Copper
Manganese
»
•-
--
--
Contaminant Parameters
SW60IO (mg/kg)
SW742I (mg/kg)
SW90I2 (mg/kg)
Lead
Molybdenum
Selenium
Vanadium
Zinc
Lead
Cyanide
-
--
--
--
--
--
•-
^SSfitSf
18.116.77
10,264.39
59.84
709.45
10.13
--
0.48
66.16
76.17
10.13
--
Jst
20100
10200
91.1
1210
IFwjufiBcy «r
betetltott ,
' .. total samples) -
16/16
16/16
16/16
16/16
LotAtiOn
Conctntrstloiii
SB-36
SB-29
SB-29
SB-36
28.2
6.23
16.4
69.1
78.5
14.5 S
1.51
16/16
15/16
14/16
16/16
16/16
16/16
1/16
SB-36
SB-53
SB-29
SB-53
SB-29
SB-36
SB-29
OJ
B = Sample result is less than the UTL calculated for the blank samples for this analyte in this media.
F = Co-elulion with a similar analyte is suspected.
H - Result given is suspected to be biased as much as 50% high.
P = Presence of analyte-is confirmed, however, concentration was not confirmed, concentration listed is a conservative estimate.
S = Concentration reported was obtained using method of standard addition.
Underline indicates the preferred resul when multiple analytical methods were performed for a single constituent.
ACM = Alaska Cleanup Matrix for Non-UST Soil.
-------
Table 3-10
Hangar 10/11 Organic and Inorganic Surface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
^Mtthod
•
ACM
Batk&rouftil Upper
Contaminant Parameters
SW8015MP (ng/kg)
SVV8080 (Mg/kg)
SW8270 (nig/kg)
Ethylbenzene
BTEX
4,4 '-ODD
4,4 '-DDE
4,4'-DDT
Aldrin
Endosulfan sulfate
alpha-BHC
2-Melhylnaphihalene
Acenaphlhene
'Anthracene.
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluorantliene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Dibenzofuran
Fluoranlhene
Fluorene
Indeno(l,2,3-cd)pyrene
Naphthalene
Phenanihrene
Pyrene
--
100,000
"
"
"
-
"
"
--
"
--
"
--
-
--
-
"
"
~
"
"
-
"
•-
--
-
-
--
- '
--
-•
-
--
•
--
--
--
--
--
--
--
--
'
--
--
'
-
--
--
Maximum
Bttetted
Frequency 0f
itOlftx filter
fty(fu 3flit11Rifi$ff
tocartcm
of Maximum
Concentration
55 H
280.28
3.08
2.42
19
1.1 H
1.05 H
0.384 H
0.17
0.0662
0.106
0.296
0.354
0.803 F
0.0874
0.803 F
0.495
0.0489
0.0515
0.63
0.0641
0.0937
0.0578 H
0.598
0.649
1/2
1/2
3/3
3/3
3/3
3/3
1/3
2/3
3/9
1/9
3/9
7/9
6/9
7/9
4/9
6/9
7/9
2/9
1/9
5/9
1/9
3/9
3/9
5/9
5/9
SB-39
SB-39
SB-34
SB-37
SB-37
SB-37
SB-37
SB-34
SB-39
SB-38
SB-38
SB-38
SB-38
SB-38
SB-32
SB-38
SB-46
SB-32
SB-38
SB-38
SB-38
SB-32
SB-37
SB-38 .
SB-38
to
-------
Table 3-10
(Continued)
Method
Indicator Parameters
SW60IO (mg/kg)
Contaminant Parameters
SW60IO (mg/kg)
SW742I (mg/kg)
SW90I2 (mg/kg)
Aft»iVw-x" "- ;
Calcium
Copper
Magnesium
Manganese
Potassium
Chromium
Lead
Molybdenum
Nickel
Selenium
Zinc
Lead
Cyanide
..
, "- * ACM , «
•-
--
--
••
--
--
.
--
--
•-
.
•-
•-
*• -. --^^
- ft^round'Dpi^,,
XTolferafc&iltol^
8,013.23
31.67
10,904.10
929.98
845.75
48.44
10.69
--
50.68
0.54
90.01
10.69
••
,,
\M»$tm«*f
V $*MNHt" - s
:;: CottttttiiraJiori '<•
8390
87.5
7810
592
594
34.9
66.1
0.984
28.6
13.3
93.9
J3.3
0.325 H
Ffeaiietttv of •. '
-.>.,. Pettetfan - A?-
;> ifcftttfctoKv :
^ \tbiA Mittjjteii^^
9/9
9/9
9/9
9/9
9/9
9/9
9/9
9/9
9/9
8/9
9/9
9/9
1/9
Locatipn;
of Maximum
Ci»tlt«(i
-------
Table 3-11
Hangar 10/11 Organic and Inorganic Subsurface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
Contaminant Parameters
SW80I5MP (Mg/kg)
SW8080 (Mg/kg)
SW8240 (Mg/kg)
SW8270 (nig/kg)
v ,
Benzene
Ethylbenzene
Toluene
Xylene (total)
BTEX
alpha-BHC
Benzene
Ethylbenzene
Mela- & Para-Xylene
Methylene chloride
Toluene
Trichloroelhene
2-Methylnaphthalene
Benzo(a)anthracene
Benzo(a)pyrene '
Benzo(b)fluoranthene
Benzo(g,h,i)perylenc
Benzo(k)fluoranthene
Butylbenzylphtlialale
Chrysene
Dibenz(a,h)anthracene
Fluorantliene
Fluorene
lndeno( 1 ,2,3-cd)pyrene
Naphllialene
PhenanUuene
l>yrene
500
-
--
--
100,000
--
1,000,000
1,000,000
1,000,000
"
1,000,000
-
-
--
-
"
"
-
-
"
"
--
'
"
"
"
.
Badltgrdttnd ttpptr
-
--
-
--
--
...
--
•-
-
-•
-
--
~
-
-
--
•-
-
.
-
;--
--
--
--
-
--
-
DcUcMd
Ot«e«Uon
(total hite/
%to(«t ftftmpltt)
ILL.
3860
526
14200
18,650.8
0.356 H
l.ll B
251
786
51.2
28.1
7.15
2.08
0.523
0.443
0.853 F
0.251
0.853 F
0.0149 H
0.478
0.134
1.11
0.115
0.241
0.701
0.858
0.819
6/28
6/28
16/28
16/28
16/28
1/5
2/28
2/28
4/28
20/28
5/28
2/28
3/26
2/26
6/26
4/26
3/26
3/26
1/26
6/26
1/26
3/26
3/26
1/26
3/26
4/26
5/26
Location
of Maximum
.. Concentration
SB-31
SB-33
SB-33
SB-33
SB-33
SB-34
SB-34
SB-33
SB-33
SB-33
SB-33
SB-37
SB-33
SB-32
SB-32
SB-32
SB-32
SB-32
SB-33
SB-32
SB-32
SB-32
SB-32
SB-32
SB-33
SB-32
SB-32
-------
Table 3-11
(Continued)
Method
Indicator Parameters
SW60IO (mg/kg)
Contaminant Parameters
SW60IO (mg/kg)
SW742I (mg/kg)
AMtyfe
Calcium
Copper
Manganese
Aiuti(Adyi> -
--
.
--
Lead
Molybdenum
Selenium
Thallium
Vanadium
Zinc
Lead
-•
--
»
--
--
-
--
* "fej'fii^
10,264.39
59.84
709.45
10.13
-
0.48
-
66.16
76.17
10.13
••SB.
10200
268
1040
24.2
1.46
11.4
9.58
67.8
171
12.6
" Frr^uenty of
Defection
^ (totalmtf , x
toM ia: mpM ••
. Location
•• of Maximum
26/26
26/26
26/26
SB-45
SB-30
SB-45
26/26
20/26
23/26
2/26
26/26
26/26
26/26
SB-37
SB-46
SB-30
SB-45
SB-45
SB-30
SB-33
B = Sample result is less than the UTL calculated Tor the blank samples Tor this analyte in this media.
F = Co-elution with a similar analyte is suspected.
H = Result given is suspected to be biased as much as 50% high.
Underline indicates the preferred result when multiple analytical methods were performed for a single constituent.
ACM - Alaska Cleanup Matrix for Non-UST Soil.
-------
from the LFI conducted by CH2M Hill in 1992. The locations of ACM exceedances are
graphically displayed on Figure 3-9. Like at the FTA, contaminant migration into the
subsurface in this area is thought to be almost vertical due to the coarse nature of the soils in
the vicinity of Hangar 10/11. Deep soil contamination at Hangar 11 may act as a continuing
source of contamination to groundwater. Sources of contamination for surface and sub-
surface soils include valve pits and underground storage tanks located southwest of
Hangar 11, and possibly a dry well on the northwest side of the Hangar. The valve pit and
underground storage tanks have been taken out of service.
Contamination associated with Hangar 8 includes low levels of NHVOCs,
SVOCs, pesticides, and metals. All metals detected were consistent with background levels.
None of the constituents detected in the surface or subsurface soils exceeded the ACM.
Table 3-12 and 3-13 summarize the analytical results for the soil COPC at Hangar 8. The
probable source for the soil contamination at Hangar 8 includes Pumphouse 2 (active), and/or
the pipes in the vicinity of the pumphouse; as well as general vehicular or air traffic.
OU4East
Contaminants of concern in OU 4 East include both NHVOCs and HVOCs, as
well as SVOCs, pesticides, and metals. All metals within OU 4 East were consistent with
background levels.
Soil contamination in the Hangar 15/Building 43-410 area included gasoline,
TCE, and TCA. Tables 3-14 and 3-15 summarize the analytical results for soil COPC in the
Hangar 15/Building 43-410 area. No results in this area exceeded the ACM. The low levels
of soil contamination detected in this area are typical of contamination resulting from paving,
or vehicular traffic. Other probable sources of contamination include a dry well and
leach field located east of Hangar 15, as well as valve pits and fuel lines located near
Building 43-410.
3-36
-------
ELMENDORF AFB
LEGEND
Soil Boring Location
Subsurface Contamination
(Greater than 5 ft.)
Soil Boring (SBS02SA10)
from LFI CH2M Hill. 1992
Results
SCALE
0 100 200
SBSD25A10
Figure 3-9. Location of Soil ACM Exceedances in the Hangar 10/11 Area,
Elmendorf AFB, AK
3-37
-------
Table 3-12
Hangar 8 Organic and Inorganic Surface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
Anatyte
- ACM*
s
Background Upper "
Contaminant Parameters
SW8080 (Mg/kg)
SW8270 (nig/kg)
4,4'-DDD
4.4'-DDE
4,4'-DDT
Endrin
gamma-BHC (Lindane)
2-Melhylnaphtlialene
3.3'-Dichlorobenzidine
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene .
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Butylbenzylphthalaie
Chrysene
Dibenz(a,h)anthracene
Dibenzohiran
Fluoranthene
Fluorene
Indeno(l,2,3-cd)pyrene
Plienanihrene
Pyrene
-
-
-
-
-
-
--
-
-
--
--
-
•
--
-
-
-
-
--
-
»
-
--
--
--
-
--
-
.--
. -
--
-
-
-
-
-
-
•
-
.
-
•'
--
•-
--
--
Maximum
Det«K$
6.81
3.29
16.8
1.21 P
1.37 P
0.0166
0.117
0.0272
0.0483
0.17
0.208
0.434 F
0.0574
0.434 F
0.046
0.223
0.0243
0.0201
0.356
0.0242
0.0613
0.307
0.387
Detection
- (total Wt«/
total samples)
Location
of Maximum
Concert talJon
1/2
2/2
2/2
1/2
1/2
1/6
1/6
1/6
1/6
3/6
3/6
4/6
2/6
3/6
1/6
3/6
1/6
1/6
3/6
1/6
2/6
3/6
3/6
SB-25
SB-25
SB-25
SB-25
SB-25
SB-35
SB-27
SB-35
SB-35
SB-35
SB-35
SB-35
SB-27
SB-35
SB 26
SB-35
SB-27
SB-35
SB-35
SB-35
SB-35
SB-35
SB-35
I
U)
00
-------
Table 3-12
(Continued)
.. / Method
Indicator Parameters
SW60IO (mg/kg)
Contaminant Parameters
SW60IO (mg/kg)
SW742I (mg/kg)
SW9012 (mg/kg)
* Awrtyte
Calcium
Copper
Magnesium
Manganese
Potassium
Chromium
Lead
Molybdenum
Nickel
Selenium
Zinc
Lead
Cyanide
4 ACHT*''*
--
-
-
-
-
-
-
'
-
-
-
-
-
toletatwe ttoR s
8.013.23
31.67
10.904.10
929.98
845.75
48.44
10.69
--
50.68
0.54
90.01
10.69
. ..
4SJ,;
9450
50.4
8430
698
794
37.8
62.5
1.47
30.2
14.5
64.2
27.3
0.579
tfetttdon
6/6
6/6
6/6
6/6
6/6
6/6
6/6
5/6
6/6
6/6
6/6
_5/5_
1/6
Location
V \
^ Qf Ivfawqum
SB-26
SB-27
SB-27
SB-25
SB-28
SB-35
SB-35
SB-28
SB-25
SB-28
SB-25
SB-26
SB-28
u>
.o
F = Co-eluiion with a similar analyle is suspected.
P = Presence of analyle is confirmed, however, concentration was not confirmed, concentration listed is a conservative estimate.
Underline indicates the preferred result when multiple analytical methods were performed for a single constituent.
ACM = Alaska Cleanup Matrix for Non-UST Soil.
* = No fuel constituents identified as COPCs at this location
-------
Table 3-13
Hangar 8 Organic and Inorganic Subsurface Soil Results for Contaminants of Potential Concern
Elmendorf AFB, AK
Method
Atwlyte
Contaminant Parameters
SW8015MP (Mg/kg)
SW8080 (>
-------
Table 3-14
Hangar 15/Building 43-410 Organic and Inorganic Surface Soil Results for Contaminants
of Potential Concern, Elmendorf AFB, AK
Method
^ Amiyte
ACM*-- , ,
B*$|!r<«ind Vppfcr .
-ifolweivc* tidbit
••^slr
Contaminant Parameters
SW8080 (fig/kg)
SW8270 (mg/kg)
PCB-1260
2-Methylnaphthalene
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g.h.i)perylene
Benzo(k)fluoranthene
Butylbeiuylphthalate
Chrysene
Dibenz(a,h)anthracene
Fluoranthene
Indeno(l,2,3-cd)pyrene
Isophorone
Naphthalene
Phenanthrene
Pyrene
--
-
--
-•
--
--
-
-- .
-
.
--
-
--
-
-•
--
-
--
--
--
--
--
-
--
-
-
--
-
'
--
-
--
--
,--
--
Indicator Parameters
SW6010 (mg/kg)
Calcium
Copper
Magnesium
Manganese
Potassium
--
-
--
-
-
8,013.23
31.67
10.904.10
929.98
845.75
35
0.132
0.0113
0.0437
0.0911
0.0681
0.209 F
0.0486 .
0.209 F
0.031
0.107
0.0167
0.181
0.0524
0.0274
0.0391 H
0.107
0.164
Frequency bf
1/2
3/6
2/6
1/6
4/6
3/6
3/6
2/6
3/6
1/6
4/6
1/6
3/6
2/6
1/6
1/6
4/6
5/6
Location bf
Maximum
SB-49
SB-43
SB-43
SB-50
SB-50
SB-50
SB-49
SB-48
SB-48
SB-48
SB-43
SB-48
SB-50
SB-49
SB-48
SB-43
SB-50
SB-50
8530
73.5
11700
760
1020
6/6
6/6
6/6
6/6
6/6
SB-44
SB-44
SB-44
SB-44
SB-44
-------
Table 3-14
(Continued)
Method
* %
Anaiyie
ACM*
f
Background Upper
f dleirance LtM(i ,
, Maximum IW«c»«tJ
;- Cdliceattilioil. :
frequency <»f
Dftfcftlfem (total
.. WWtdifil samples)
Lotion of
M»xto»w»
CanettiiHrfteii
Contaminant Parameters
SW6010 (mg/kg)
SW7421 (nig/kg)
Chromium
Lead
Molybdenum
Nickel
Selenium
Zinc
Lead
--
--
--
--
•-
--
••
48.44
10.69
--
50.68
0.54
90.01
10.69
39.6
30.4
1.04
49.9
13.4
90
3L3
6/6
6/6
5/6
6/6
6/6
6/6
6/6
SB-44
SB-49
SB-48
SB-44
SB-44
SB-44
SB-49
K)
B - Sample result is less than the UTL calculated for the blank samples for this analyte in this media.
F - Co-elution with a similar analyte is suspected.
H - Result given is suspected to be biased as much as 50% high.
Underline indicates the preferred result when multiple analytical methods were performed for a single constituent.
ACM - Alaska Cleanup Matrix for Non-UST Soil.
* - No fuel constituents identified as COPCs at this location.
-------
Table 3-15
Hangar 15/Building 43-410 Organic and Inorganic Subsurface Soil Results for Contaminants
of Potential Concern, Elmendorf AFB, AK
Method
Analytt
ACM \
% V
Background VpfMMr ••
.tofoaaw y«it
Maximum
vfo*tefi**d "
&W*mW
-------
Numerous contaminated soil intervals were identified at the ADSA. Contami-
nants detected in the surface soils in the ADSA include NHVOCs, SVOCs, pesticides, and
metals. Only one constituent exceeded the ACM in the surface soils: diesel (110,000
mg/kg).
Two constituents, jet fuel (2,100 mg/kg) and "Unspecified Compounds hi the
Gasoline Range" (15,600 mg/kg), exceeded the ACM in subsurface soil sample results.
Each of these constituents represent non-speciated results, and are therefore not included in
the analytical summary tables. The heavy hydrocarbons present in the deep soils may result
in slow contaminant degradation. Deep contaminants hi this area may also act as a source of
contamination to groundwater. All subsurface ACM exceedances occurred in samples from
soil boring SB-12 (Figure 3-10).
Tables 3-16 and 3-17 summarize the analytical results, and locations of the
highest detected concentrations for all COPC in surface and subsurface soils at the ADSA.
The locations of these exceedances are depicted on Figure 3-10.
Sources for the contamination seen at the ADSA include residue from former
asphalt storage, and fuel or other spills from drums stored hi the area. Pesticide contamina-
tion is likely the result of historical insect control activities. There is no known
anthropogenic source for the majority of the metals detected in the ADSA soils. All drums
have been removed, the first few inches of soil have been removed, and the area has been
revegetated.
3.2 Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human
health and environmental risk assessments were performed to determine if areas should be
considered for remedial action. All concentrations of contaminants, including all potential
3-44
-------
——--£; f
ELMENDORF AFB
LEGEND
Suspected Fuel Spill
Asphalt Spill
Former Drum Location
Soil Boring Location
Surface Soil Location
Surface Contamination
(Less than 5 ft.)
Subsurface Contamination
(Greater than 5 ft.)
NOTE: Drum locations are based on EA Engineering,
Science, and Technology, 1992
Figure 3-10. Location of Soil ACM Exceedances at the Asphalt Drum Storage Area,
ElmendorfAFB,AK
3-45
-------
Table 3-16
Asphalt Drum Storage Area Organic and Inorganic Surface Soil Results for Contaminants of
Potential Concern, Elmendorf AFB, AK
Method
AoaJyte
- ; ACM
Background Upper
, Maxunttra
Defected
-- " . *
jfreqiRBcy of
Delation <
(total hit*/
..- fotsl $wmjrti&)
tocalfcm
of Maxim urn
" ttowfflslwfttaw
Contaminant Parameters
SW801SMP
-------
Table 3-16
(Continued)
" Method
SW8270 (mg/kg)
' Ansiyte
Toluene
Trichloroethene
2-Methylnaphthalene
4-Methylphenol(p-cresol)
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)ftuoranihene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Butylbenzylphlhalate
Chrysene
Dibenz(a,h)anthracene
Dibenzofuran
Dibutylphthalate
Fluoranihene
Fluorene
Naphthalene
Phenanthrene
Phenol
Pyrene
bis(2-Ethylhexyl)phthalate
ACM , >
1,000,000
--
--
--
--
--
--
--
•-
.
•-
'
--
--
--
--
--
--
"
--
--
--
--
--
teKkgrQurttl tipptr
TolerSittfeJLftnlt:
•
--
•-
--
--
--
--
--
--
-•
-•
--
--
- .
-
--
-•
-- •
--
--
--
--
--
--
Maximum
, iWetied
* C0n?tirtrdti6a
0.835 B
2.08
2.04
0.0197 F
1.5
0.0382
0.641
0.554 F
0.952
0.669 F
0.1
0.669 F
0.102
1.48
0.0311
1.2
0.0508
1.51
1.35
7.49
3.82
0.0417
1.18
5.59
Frequency of
Defection
(WtflthitS/
.. total Saitipt*S)
1/20
1/20
14/27
2/27
8/27
1/27
6/27
11/27
7/27
11/27
2/27
7/27
2/27
16/27
1/27
6/27
4/27
11/27
7/27
11/27
11/27
1/27
14/27
16/27
Location
, of Maximum
Concentration
SS-06
SS-14
SS-14
SS-09
SS-14
SS-14
SS-14
SS-15
SB-02
SB-02
SB-03
SB-02
SB-04
SB-02
SS-09
SS-14
SS-OI
SS-14
SS-14
SS-14
SS-14
SS-14
SS-14
SS-02
Indicator Parameters
SW60IO (mg/kg)
Aluminum
Calcium
--
--
31.183.96
8.013.23
24500
8090
26/26
26/26
SB-ll
SS-10
is
-------
Table 3-16
(Continued)
Method
SW60IO (mg/kg)
Contaminant Parameters
SW6010 (mg/kg)
SW7421 (mg/kg)
SW9012 (mg/kg)
AnSflyte
Copper
Iron
Magnesium
Manganese
Potassium
Chromium
Cobalt
Lead
Molybdenum
Nickel
Selenium
Vanadium
Zinc
Lead
Cyanide
\
ACM
--
--
.
--
--
-
--
--
--
--
--
--
--
--
ttfcdkgrflUnrf Upptr
TolerOnceUnlt
31.67
43,192.35
10.904.10
929.98
845.75
48.44
19.52
10.69
-
50.68
0.54
101.64
90.01
10.69
--
Mftgtanfc*
Dtutttd
Cbncfeiitra«Mii ,
34.1
34300
12700
969
932
41.6
15.9
501
6.3
56.7
13.1
78.1
'76.6
546
3.6
Frequency of
Detection.
•• (toiflihM
-•. total pmijptttV
26/26
26/26
26/26
26/26
26/26
26/26
26/26
26/26
26/26
26/26
24/26
26/26
26/26
26/26
3/27
Location
of Maximum
Ci)i»centraUon
SB-03
SS-16
SS-12
SB-04
SS-10
SS-12
SS-12
SS-10
SS-16
SS-12 3
SS-10
SS-OI
SS-15
SS-10
SS-02
00
B = sample result is less than the UTL calculated for the blank samples for (his analyte in this media.
F = co-elution with a similar analyte is suspected.
H = result given is suspected to be biased as much as 50% high.
P = presence of analyte is confirmed, however, concentration was not confirmed, concentration listed is a conservative estimate.
Underline indicates the preferred result when multiple analytical methods were performed for a single constituent.
ACM = Alaska Cleanup Matrix for Non-UST Soil.
-------
Table 3-17
Asphalt Drum Storage Area Organic and Inorganic Subsurface Soil Results for Contaminants
of Potential Concern, Elmendorf AFB, AK
1 Method
Contaminant Parameters
SW80I5MP (Mg/kg)
SW8080 (Mg/kg)
SW8240 (Mg/kg)
SW8270 (mg/kg)
Ethvlbenzene
Xvlene (total)
4,4'-DDD
4,4'-DDE
4,4'-DDT
Aldrin
Dieldrin
Endosulfan sulfate
Heptachlor
Heptachlor epoxide
beta-BHC
delta-BHC
gamma-DHC (Lindane)
Ethylbenzene
Meta-& Para-Xylene
Methylene chloride
Ortho-Xylene
2-Methylnaphthalene
Denzo(g,h,i)perylene
Butylbenzylphthalate
Chrysene
Dibulylphlhalale
Pluorene
Naphthalene
Phenanlhrene
AC* ^ '
.wgg^iy
J3SL
Frequency of
(Wttl hits/
totStiOrt
of Maximum
-
-
-
-
-
-
•
-
-
-
-
-
-
1,000,000
1,000,000
"
1,000,000
-
•
"
-
"
-
"
"
"
"
"
~
~
"
"
"
"
"
"
"
"
.
-
--
. --
"
"
• "
"
"
"
"
71700
II 0000
7.82
3.84
13.9
3.07
1.22 P
5.14
0.845
0.346 B
3.3
1.46 H
1.1 H
6760
8780
226
11900
22.4
0.947
0.016 H
0.543
0.0501
0.994
9.59
0.584
4/32
J4/32
2/15
1/15
6/15
5/15
2/15
6/15
1/15
2/15
1/15
1/15
4/15
1/29
2/29
9/29
2/29
4/37
2/37
2/37
3/37
1/37
1/37
3/37 .
2/37
SB-12
SB-12
SB-09
SB-09
SB-09
SB-03
SB-03
SB-03
SB-OI
SB-09
SB-OI
SB-03
SB-03
SB-12
SB-12
SB-12
SB-12
SB-12
SB-12
SB-IO
SB-12
SB-03
SB-12
SB-12
SB-12
-------
Table 3-17
(Continued)
MtthOrt
Indicator Parameters
SW60IO (nig/kg)
Analytt
ToJerant* titnif
Calcium
Copper
Magnesium
Manganese
Potassium
--
-
--
--
--
Contaminant Parameters
SW6010 (mg/kg)
SW742I (mg/kg)
Lead
Molybdenum
Selenium
Vanadium
Zinc
Lead
--
-
-
--
-
«
10,264.39
59.84
14,784.34
709.45
1,114.35
10.13
-
0.48
66.16
76.17
10.13
' Cftlttfcittariitftt
50400
216
16000
988
1640
-" \ > (total tote/
34/34
34/34
34/34
34/34
34/34
15.6
12.3
19.9
86.9
155
18.8 S
34/34
31/34
28/34
34/34
34/34
34/34
of Maximum
•: Contahtwion
SB-05
SB-06
SB-It
SB-09
SB-05
SB-03
SB-09
SB-09
SB-09
SB-06
SB-05
OJ
U)
o
B = Sample result is less than the UTL calculated for the blank samples for this analyle in this media.
II = Result given is suspected to be biased as much as 50% high.
P = Presence of analyte is confirmed, however, concentration was not confirmed, concentration listed is a conservative estimate.
S = Concentration reported was obtained using method of standard addition.
Underline indicates the preferred result when multiple analytical methods were performed for a single constituent.
ACM = Alaska Cleanup Matrix for Non-UST Soil.
-------
contaminants of concern, whether exceeding maximum contaminant levels (MCLs), or
Alaska Cleanup Matrix standards or not, were included in the risk assessments.
3.2.1 Human Health Risk Assessment (HRA)
By determining under what land use conditions people are potentially exposed
to what chemicals, for how long, and by what pathways of exposure, the cancer and non
cancer risks were determined in the RI/FS.
Exposed Populations and Exposure Pathways — Listed below are five
possible exposure pathways to contamination. Details on the parameters used in the Health
Risk Assessment are shown on Table 3-18.
Future On-Site Resident: The HRA evaluated exposure of residents
to contaminated surface soil through direct contact (incidental ingestion
and dermal absorption) and inhalation of dusts. Their exposure to
shallow aquifer groundwater through ingestion, inhalation (showering),
and dermal contact (showering) was also evaluated.
Future On-Site Worker: The HRA evaluated exposure of workers to
contaminated subsurface soil through direct contact (dermal absorption
and incidental ingestion), and inhalation of vapors from the soil. Inges-
tion of on-site water was also evaluated.
Current On-Site Worker: The HRA evaluated exposure of workers to
contaminated surface soil through direct contact (incidental ingestion
and dermal absorption) and inhalation of dusts.
Construction Worker: The HRA evaluated exposure of short term
construction workers to contaminated subsurface soil through direct
contact (incidental ingestion and dermal absorption) and inhalation of
dusts.
»
Hypothetical Visitor: The HRA evaluated exposure of an adult and
child visitor to contaminated surface soil through direct contact (inci-
dental ingestion and dermal absorption) and inhalation of dusts.
3-51
-------
Table 3-18
Exposure Assumptions for OU 4
Lft
to
Parameters
Body Weight (kg)
Exposure Duration (yrs)
Averaging lime (carcinogens) (yrs)
Averaging time (noncarcinogens) (yrs)
Total inhalation rate (mj/day)
Soil Ingestion/Contact
Soil Ingeslion Rate (mg/day)
Soil to Skin Adherence Factor
(mg/cm2)
Exposed Skin
Exposed Frequency (days/yr)
Exposure Duration (yrs)
Water Use
Water Ingestion (L/day)
Indoor Inhalation Rate (m3/day)
lixposure Frequency (days/yr)
Skin Surface (cm2)
Shower Duration (min)
Hypothetical On.Site Rcsitfcatiol
Adult
RME
70"
30'
70d
NA
20d
200/100
lf
5000 k
185 g
24/6k
2A"
15'
350'
23000 '
IS1
A*er*gfe
70"
9b
70d
NA
20d
100b
.02'
1900 b
1108
9b
1.4"
15 "
275"
20000 f
10f
child
RMB
15 "
6d
N
6d
16°
200/100
lf
3900 b
185*
24/6b
. .07e
12°
350"
10,600 f
15'
AVOW
15«
6d
NA
6d
16e
100b
0.2'
1900b
110
6
0.419
12
275
8,660
10
Qp.$$itQc$ff|ta
-------
Exposure Assumptions — Risk can be calculated both for the average
exposure and the reasonable maximum exposure (RME) of the population. All chemicals
detected during sampling were evaluated as potential sources of cancer and noncancer health
risks. In the case of metals, risks were only calculated if the metals concentrations exceeded
back-ground concentrations. Average exposure risks were assessed using the measured con-
centrations at the site. RME risks were assessed using the 95% upper confidence limit
v
(UCL) of the arithmetic mean concentration in soil and groundwater in subareas such as
Hangar 11 or the FTA.
Using exposure levels and standard values for the toxicity of contaminants,
excess lifetime cancer risks (ELCRs), and hazard indices (His), were calculated to describe
cancer and noncancer risks, respectively. The ELCR is the additional chance that an individ-
ual exposed to site contamination will develop cancer during his/her lifetime. It is expressed
as a probability such as 1 x 10"6 (one in a million).
The HI estimates the likelihood that exposure to the contamination will cause
some negative health effect. An HI score above one indicates that some people exposed to
the contamination may experience at least one negative health effect.
ELCRs and His were calculated using Reference Doses (RfDs) and Cancer
Slope Factors (CSFs), which represent the relative potential of compounds to cause adverse
noncancer and'cancer effects, respectively.
Two sources of RfDs and CSFs were used for this assessment. The primary
source was Integrated Risk Information System (IRIS) database, the USEPA repository of
agency-wide verified toxicity values. If a toxicity value was not available through IRIS, then
the latest available quarterly update of the Health Effects Assessment Summary Tables
(HEAST) issued by the USEPA's Office of Research and Development was used as a
secondary source. For some chemicals detected at OU 4, no toxicity value from IRIS or
3-53
-------
HEAST was available, and toxicity values were provided by EPA Region X as provisional
RfDs and cancer slope factors.
Table 3-19 summarizes the carcinogenic and noncarcinogenic human health
risks calculated for each of the six areas within OU 4. The risks are based on hypothetical
exposure to soil and groundwater. This shallow groundwater aquifer is not presently used,
and will not be used in the future for supplying potable or non-potable water. For carcino-
genic soil risk, the calculated results for the future resident (RME) and current on-site
worker scenarios, which evaluate surface soil risks, are listed. The construction worker
scenario results, which evaluates deep soil risk, is also provided. For carcinogenic ground-
water risk, the calculated results for the future resident (RME), and future on-site worker
scenarios are provided.
Risks exceeded 1 x 10"* in groundwater in three areas: the FTA, Hangar 14,
and Hangar 11. This risk occurs only when future residents drink and bathe with the shallow
aquifer groundwater in the area for 30 years. The actual, presently existing risk posed by
the shallow groundwater is significantly less than the worst case risk shown in the future
residential column in Table 3-19. At the FTA and Hangar 14, the risk drops to below
1 x 10^ under the future on-site worker scenario. For soil risk, only the FTA had a soil risk
in excess of 1 x 10"5, this occurring under the most conservative scenario for shallow soils.
Under the current on-site worker scenario, only Hangars 8 and 10/11 and 10 had shallow soil
risks greater than 1 x 10"6. No subsurface soil risks exceeded 1 x 10'6.
3.2.2 Environmental Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemi-
cals or calculated exposures to plants and wildlife at OU 4 are likely to produce adverse
effects. Ecological effects were evaluated quantitatively by calculating Ecological Quotients
(EQs). EQs are defined as the ratio between measured concentrations or predicted expos-
ures, and critical effects levels. If an EQ is less than 1.0, the effect is unlikely to occur.
3-54
-------
Table 3-19
Summary of Human Health Risks at Operable Unit 4, Elmendorf AFB, AK
-
FTA
Hangar 14
Hangar 10/11
Hangar 8
Hangar 15
ADSA
&*!&*«
ShalowSBil*t<5ra*>
*S*> ''•
2.7x10 "s
23x10-*
4.1x10-*
33x10"*
2.1x10-*
3.1x10"*
Winkers*
-------
Critical effects are defined in the selection of assessment and measurement endpoints.
Assessment endpoints are the general environmental resource or value that is being protected.
A measurement endpoint is a specific criterium that is used to evaluate the more general
assessment endpoint.
Compared to undeveloped portions of the base, the sites that comprise OU 4
do not contain major ecological resources. The naturally occurring vegetation has been
removed from most of the areas. The existing vegetation in the contaminated areas varies
from barren to sparse grassy areas. The species diversity is much lower in OU 4 than in any
of the undeveloped portions of the base.
The ERA focused on evaluating potential impacts of the contamination on the
selected indicator species: moose and meadow vole. Because of its large home range, the
moose's exposures to OU 4 contaminants were small, resulting in EQs well below 1.0 for all
chemicals. Although the meadow vole EQs for copper and lead exceeded 1.0 at many sites,
EQs for background concentrations also exceeded 1.0, indicating that the methodology is
overly conservative and hot useful for evaluating low level contamination. Although the EQs
for selenium also exceeded 1.0, the uniform concentrations of selenium at all sites appear to
be naturally occurring and not indicative of contamination.
No significant impacts to plants or animals warranting action were determined
to be present based on the results of the ERA.
Uncertainties Associated with the Risk Assessment
Risk assessments involve calculations based on a number of factors, some of
which are uncertain. The effects of the assumptions and the uncertainty factors may not be
known. Usually, the effect is difficult to quantify numerically, so the effect is discussed
qualitatively. Some of the major assumptions and uncertainty factors associated with the risk
3-56
-------
assessment are the following:
Existing concentrations are assumed to be the concentrations in the
future. No reduction through natural degradation and attenuation over
time is taken into account (may overestimate risk).
No increase through additional contamination is assumed (may under-
estimate risk).
Potential degradation products of existing organic contaminants are not
considered (may overestimate or underestimate risk).
Potential effects on the moose and meadow vole are assumed to be
representative of other animals at OU 4 (may overestimate or underesti-
mate risk).
3.3 Summary
Actual or threatened releases of hazardous substances from OU 4, if not
addressed by implementing the response action selected in this ROD, may present an immi-
nent and substantial endangerment to public health, welfare, or the environment.
3-57
-------
[This page intentionally left blank.]
-------
4.0 REMEDIAL ACTION OBJECTIVES, ALTERNATIVES, AND
COMPARATIVE ANALYSIS
The following subsections discuss the remedial action objectives for OU 4, and
present a description of the various cleanup alternatives which were evaluated to achieve
those remedial objectives. The results of the detailed comparison made between those alter-
natives are also presented.
4.1 Contaminants of Concern (COCs)
COCs were developed from the results of the risk assessment and by consider-
ing regulatory standards. Each constituent having an individual contribution of greater than
1 x 10* carcinogenic (RME) risk, or an HI greater than 1.0, was selected as a COC. In
addition, any constituent exceeding potential cleanup levels (MCLs for groundwater or ACM
levels for soil) was also considered a COC. The final COCs are shown on Table 4-1, with
the individual risk contributed and basis for identifying the COC (risk or regulatory stan-
dard). The cleanup levels that will be achieved by the remedial action at OU 4 are also
listed in Table 4-1.
4.2 Remedial Action Objectives
Specific remediation alternatives were developed and evaluated for the areas
with potential risk, and that exceeded the cleanup levels identified in Section 3.3. Specific
remedial action objectives are:
• Protect human health and the environment by preventing ingestion of
and contact with contaminated media by people;
• Protect uncontaminated media by preventing releases from sources;
• Use treatment techniques whenever practicable; and
4-1
-------
Table 4-1
Summary of Contaminants of Concern ! Analysis, Operable Unit 4
Elmendorf AFB, AK
CfcOtaleal
Maximum
C<»nceiitratlOrt
ftfftxtnram
Canc*iriUsk
MA)tJiriMW
s f f "tfiv-dtifiiil '"'•
w'|OBeX ^ ^V^
,*:' M&tteOdC v
% ' s •.
Cleanup Level
Basis for
Cleanup
i*v«£
Ground water:
Benzene
1,1-Dichloroethene
1 ,2-Dichloroethane
Trichloroethene
Dieldrin
Chloroform
Chioromethane
Carbon Tetrachloride
Vinyl Chloride
Toluene
Ethylbenzene
cis- 1 ,2-Dichloroethene
Tetrachloroethene
1,1,1-Trichloroethane
2,600 /tg/L
13.7/tg/L
12.1 /tg/L
74.7 /tg/L
0.0335 /tg/L
2.72 /tg/L
11. 7 /tg/L
1.26 /tg/L
O.I 25 /tg/L
5,590 /tg/L
1,360 Mg/L
741 /tg/L
40.5 /xg/L
23 /tg/L
3.5E-03 '
2.8E-04h
1.3E-05b
1.3E-05b
3.0E-05 c
5.2E-06"
2.9E-06"
2.2E-060
1.6E-06
~"
*.
"
*•
«
~
~
"
0.19"
--
~
-
'
--
6.3*
2.6'
0.61"
0.17"
••
Exceeds MCL; contributes to
a risk > 10 •*
Exceeds MCL; contributes to
a risk > 10 *
Exceeds MCL; contributes to
a risk > 10*
Exceeds MCL; contributes to
a risk > 10"6; contributes to
HQ>0.1
Contributes to a risk > 10*
Contributes to a risk > 10"*
Contributes to a risk > 10*
Contributes to a risk > 10*
Contributes to a risk > 10*
Exceeds MCL; contributes to
HQ>0.1
Exceeds MCL; contributes to
HQ>0.1
Exceeds MCL; contributes to
HQ>0.1
Exceeds MCL; contributes to
HQ>0.1
Exceeds MCL
5/ig/L
7/xg/L
5/xg/L
5/xg/L
--
100 /tg/L
-
5 /tg/L
2 /tg/L
1000 /tg/L
200 /tg/L
70 /tg/L
5 /tg/L
200 /xg/L
MCL
MCL
MCL
MCL
--
MCL
-
MCL
MCL
MCL
MCL
MCL
MCL
MCL
-------
Table 4-1
(Continued)
Chemical ,
Soils:
Benzo(a)pyrene
Benzo(b)fluoranthene
Dibenz(a,h)anthracene
Benzo(a)anthracene
PCB-1260
Benzo(k)fluoranthene
Indeno(l,2,3-cd)pyrene
Benzene
BTEX
Diesel
Gasoline
Jet Fuel
Kerosene
Maximum
Coheehtrjition
2.21 mg/kg
'4.72 mg/kg
0.54 mg/kg
2.18 mg/kg
151 ftg/kg
4.72 mg/kg
0.897 mg/kg
715 /ig/kg
186,040 fig/kg
110,000 mg/kg
15,600 mg/kg
13, 000 mg/kg
2,200 mg/kg
MaxiraW ••
"OrBt»r$U!&:
1.8E-05'
3.6E-06'
3.0E-06'
2.0E-06e
1.9E-06'
1.7E-06'
1.3E-06'
-
--
--
--
--
—
Maximum
- Hazard --
-rrjfatafrv-^
. .?. \^\...i\\ .-... .:•.. .
_
~
--
--
--
-
--
~
--
--
--
-- •
--
, r \ &m;foM2 10*
Contributes to a risk > 10*
Contributes to a risk > 10*
Contributes to a risk > 10*
Contributes to a risk > 10"*
Contributes to a risk > 10*
Contributes to a risk > 10*
Exceeds ACM
Exceeds ACM
Exceeds ACM
Exceeds ACM
Exceeds ACM
Exceeds ACM
£lw»iWj»,Uv«l
~
--
-
--
-
-
~
500 fig/kg
100,000 /ig/kg
2000 mg/kg
1000 mg/kg
2000 mg/kg
2000 mg/kg
B*$i9 for
Cleartup
JUvel-x
~
--
-
«
--
--
-
ACM
ACM
ACM
ACM
ACM
ACM
'Cancer risk > I OE-06 or HQ>0.1 for soil or groundwater scenario with total HQ of > 1.0; or concentrations found
in excess of regulatory levels. If cancer risk or HQ did not exceed standards, it was marked as "-V.
' Risk calculated for Hangar 11 Area Plume.
b Risk calculated for Fire Training Area Plumes.
* Risk calculated for Hangar 14 Area Plume.
d Risk calculated for Hangar 15/Building 42-410 Area Plume.
• Risk calculated for Fire Training Area Soil.
MCL = Maximum Contaminant Level.
ACM = Alaska Cleanup Matrix, Level D.
-------
Implement a cost effective solution that can achieve the cleanup levels
for the final COCs.
These remedial action objectives are applicable for all contaminated groundwater and soil
areas.
Measures to meet the second objective have already been taken. At
Hangar il, the leaking USTs and valve pit were taken out of service. The floor drams in
the hangars are no longer used. At the FTA, fire-fighting activities have been stopped and a
leaking UST was removed. The drums and surface soil at the ADSA were removed and
trees were planted.
4.3 Alternatives
As discussed above, the primary COCs are nalogenated and non-halogenated
volatile organic compounds in groundwater, and semi-volatile organic compounds (SVOCs)
and fuel constituents in soils. Cleanup alternatives were developed for groundwater and soil,
therefore, the development of alternatives was segregated accordingly. Soil alternatives were
divided into those applicable to shallow soils and those applicable to deep soils. Each alter-
native was evaluated for each source area.
The four most promising groundwater alternatives ("G") and five most promis-
ing soil alternatives ("S") were chosen on the basis of the nine CERCLA criteria. These
included no action (Gl, SI); institutional controls with intrinsic remediation (G2, S2); in-situ
air sparging (G3); excavation and recycling (S3); in-situ bioremediation (G4); excavation,
biopiling, and backfilling (S4); and in-situ bio venting (S5).
Time to complete cleanup for biological alternatives was calculated using first
order decay, with the most conservative published values of half-lives for the primary con-
taminant of concern at each source area. Biological alternatives include intrinsic
4-4
-------
remediation(S2), biopiling (S4), and bioventing (S5). For shallow and above ground
biological soil treatments, little or no treatment was assumed to occur during the winter
months. For groundwater, a two-dimensional fate and transport model was used which
considers biodegradation, retardation, advection, dispersion, and adsorption/desorption.
Cleanup times for each alternative are presented in the discussion below. This model did not
consider soil contamination as a continuing source of contamination to groundwater, but it
did consider retardation caused by contaminants adhering to soil particles.
Except for the no action alternative, the cost of each alternative includes moni-
toring of soil and groundwater for the estimated time period to complete clean up, up to a
maximum of 30 years, in accordance with CERCLA guidance. Net present value cost was
calculated using a seven percent discount rate. Costs estimates were calculated using the
USAF RACER model and have an accuracy of -30% to +50%.
The alternatives are as follows:
Alternatives Gl and SI: No Action (Groundwater and Soils)
There are no costs associated with this alternative.
Evaluation of this alternative is required by CERCLA as a baseline reflecting
current conditions without any cleanup. This alternative is used for comparison with each of
the other alternatives. It does not take into consideration future events such as intrinsic
remediation, however, intrinsic remediation is expected to occur. As a result, cleanup levels
are expected to be achieved within the same timeframe as the intrinsic remediation alternative
(thirteen years for groundwater and eleven years for soil). This alternative does not include
long-term monitoring, controls, or access restrictions; therefore, potential exposure pathways
would not be eliminated and future degradation would not be monitored.
4-5
-------
Alternatives G2 and S2: Institutional Controls with Intrinsic Remediation
(ICIR) (Groundwater and Soils)
Costs and time to cleanup for these alternatives are presented in Table 4-2.
Groundwater and soil would be remediated by natural processes (physical,
chemical, and biological) that reduce contaminant concentrations. A study of intrinsic
remediation at Elmendorf AFB was conducted by AFCEE. The results of this study indicate
that contamination is degrading. Base-wide modeling conducted under OU 5 RI/FS indicates
contamination will be reduced. Contaminants should degrade to regulatory levels within 13
years. While intrinsic remediation is working, existing land use restrictions would continue
to be used to limit access to contaminated groundwater and soil. Land use restrictions are
part of the Base Comprehensive Plan. Hazardous areas will be posted with warning signs.
These controls would prohibit construction of residences and groundwater wells over areas
with contaminant plumes, and prohibit excavation of soil in areas of soil contamination that
exceed acceptable levels. The USAF would continue to monitor groundwater quality semi-
annually, and soil quality bi-annually until cleanup levels are achieved. If there is any
indication that intrinsic remediation is not achieving the cleanup levels within the expected
timeframes, the remedial actions would be reevaluated and additional action taken if
necessary.
Alternative G3: In Situ Air Sparging (Groundwater)
Costs and time to cleanup for this alternative are presented in Table 4-3.
In Alternative G3, air sparging wells would be installed in the area of
contaminated groundwater. Air would be injected into the wells and be sparged (blown) into
the groundwater below the water table. As the air passes through the contaminated ground-
water, the contaminants of concern would be stripped from the water phase into the gas
phase.
4-6
-------
Table 4-2
Costs and Time to Cleanup for Alternative G2 and S2, Operable
Unit 4, Elmendorf AFB, AK
'„',''',;,",/ ' , '
' •• "-.'t , '-,-. -,;-'...», £
-'-'" '-- --'-
, ' ^Swer«e|SnKi»' x ; -^
?/^;>" '-' ' ' ^Go&'&tev&^fa^'fy/*- •••• ^ -f''-,^y
% :/ ^' ,f
!;>f';<"'«$Tvsss&^ '. M
{% ""'Worth^ ,,J
'^;t t-.s ' ; '- , }
9
3
6
3
3
8
76
10
27
12
14
61
8
11
2
4
3
4
4-7
-------
Table 4-3
Costs and Time to Cleanup for Alternative G3 and S3, Operable
Unit 4, Elmendorf AFB, AK
Alternative G3:
FTA
650
152
1642
Hangar 8
767
86
992
Hangar 10/1 1
171
55
389
Hangar 14
115
64
334
Hangar 15
126
51
336
FTA
1876
1876
Hangar 8
136
136
Hangar 10/11
Hangar 14
Hangar 15
ADSA
314
307
161
374
314
307
161
374
4-8
-------
In addition, some of the oxygen would dissolve into the groundwater, creating
an aerobic environment that would enhance biodegradation of some of the remaining
contaminants. Some of the contaminants could migrate to the land surface and be emitted to
the atmosphere. This alternative also would rely on land use restrictions and the monitoring
program described in Alternative G2.
Alternative S3: Excavation and Recycling (Soil)
Costs and time to cleanup for this alternative are presented hi Table 4-3.
Alternative S3 consists of excavating the contaminated shallow soils and trans-
porting them to a commercial recycling facility hi the Anchorage area. Excavations would
be backfilled with clean soil. At the recycling facility, the contaminated soils typically are
treated in a low-temperature thermal treatment unit designed to remove volatile contaminants
from the soil. The soil is then recycled for road base or other projects. This alternative was
developed for shallow soils (15,000 in-place yd3) only, because excavating all contaminated
deep soils (an additional 20,000 in-place yd3) would not be a cost-effective or technically
feasible alternative.
Alternative G4: In Situ Bioremediation (Groundwater)
Costs and time to cleanup for this alternative are presented in Table 4-4.
In this alternative, a series of wells would be installed to extract contaminated
groundwater. Extracted groundwater would be piped above ground to a mixing tank, where
the pH is adjusted and oxygen and nutrients are added. The groundwater would then be
reinjected into the aquifer through injection wells to biodegrade dissolved contaminants in
place. When compared with other contaminants, the principal contaminants, halogenated
volatile organic compounds (HVOCs) at Hangar 15/Building 43-410, and at part of the FTA,
are more resistant to bioremediation. Therefore, Alternative G4 would not be as effective at
4-9
-------
Table 4-4
Costs and Time to Cleanup for Alternative G4 and S4, Operable
Unit 4, Elmendorf AFB, AK
'% ' ' 5 •*
f: ,^, < *
',' ': ',
.. •SkHtreeA'OS* , .,, .,,, ,,
Alternative G4: lo Sita Bie
FTA
HangarS
Hangar 10/11
Hangar 14
Hangar 15
\ ^ "•
FTA
Hangar 8
Hangar 10/1 1
Hangar 14
Hangar 15
ADSA
' ' ' -f
f f
•• •••• ••••''••••
.,-, £qgto&t ..,
Fei8«idlatite» (<5r<«
843
1640
444
228
438
589
52
124
112
58
147
*v»+,v
•T*>««.'4» ' ' ^"
V ^qirtip ;'-''-
V '/&*fcG0S'*'-T<
^ ' f j f ' V •••"^
•• -.vv •. / -*^-
8
3
3
4
5
f f
1
1
1
1
1
1
4-10
-------
treating the ground water at these two sites. This alternative also would rely on land use
restrictions and the monitoring program described in Alternative G2.
Alternative S4: Excavation, Biopile, Backfill (Soils)
Costs and time to cleanup for this alternative are presented in Table 4-4.
Alternative S4 consists of excavating contaminated shallow soils, transporting
them to an on-base biopile cell, treating the soils until acceptable levels are reached, and
backfilling the excavations with treated soil or other clean borrow material from on base. At
the biopile cell, soils would be mounded over a series of perforated pipes on top of an imper-
meable liner. Air drawn through the overlying pile would enhance aerobic degradation of
organic contaminants and strip the volatile constituents from the soils. Soil from the pile
would be sampled periodically to determine the progress of the remediation. Once the soil is
remediated, it would be used for backfill on base.
Alternative S5: In Situ Bioventing (Soils)
Costs and time to cleanup for this alternative are presented in Table 4-5.
In bioventing, air is injected into the soils to increase the oxygen content. By
increasing the oxygen content of the soil gas, bioventing increases aerobic degradation of the
contaminants by naturally occurring microorganisms. Unlike Alternatives S3 and S4, this
alternative was developed to address only deep soil contamination. Bioventing is considered
highly effective for deep soil contamination. In addition, Alternative S5 calls for the land
use restrictions and soil monitoring described in Alternative S2.
4-11
-------
Table 4-5
Costs and Time to Cleanup for Alternative S5, Operable
Unit 4, Elmendorf AFB, AK
••. * ,
' ' f - ',"•*.-• ,'"•••••{ -^ •v
','"•'..'' '-.'"••.
- ' ' "
FTA
90
46
173
HangarS
NA
NA
NA
NA
Hangar 10/1 1
43
18
76
Hangar 14
NA
NA
NA
NA
Hangar IS
Bldg 43-410
42
11
53
ADSA
43
27
92
NA = Not Applicable
4-12
-------
4.4 Summary of Comparative Analysis of Alternatives
The comparative analysis describes how each of the alternatives meet the
CERCLA evaluation criteria relative to each other.
4.4.1 Threshold Criteria
Overall Protection of Human Health and the Environment
For groundwater, Alternative G3 (air sparging) would provide the greatest
protection of human health and the environment from a technical standpoint, because ground-
water would be actively treated to acceptable levels. Contaminants would be removed from
the groundwater, and be biodegraded or released to the atmosphere. Alternative G4 (in situ
bioremediation) is slightly less protective, because although it is an active treatment, it may
not be effective for treating the HVOCs which are present at the FTA and Hangar 15.
Active treatment of the groundwater is essential where a more immediate removal of the con-
tamination is required, such as if the groundwater is currently being used. Alternative G2
(institutional controls with intrinsic remediation, or ICIR) is not an active treatment,
however, it provides some protection of human health and the environment in that the
institutional controls associated with this alternative would reduce contact with contaminated
groundwater and thus there would continue to be no groundwater risk. Monitoring would
also ensure that the institutional controls continued to effectively prohibit groundwater
contact, by making sure that the groundwater plumes associated with the OU 4 source areas
do not migrate beyond these restricted areas. Alternative Gl (no action) is the least
protective, since there would be no institutional controls and no monitoring, so that future
contact with groundwater contaminants would still be possible. For each of the five
groundwater plumes at OU 4, removal of the source is essential to meeting this criteria. As
previously stated, the sources for each of the plumes with high levels of contaminants (FTA,
Hangar 11, and Hangar 8) have been decommissioned, removed, or will be treated (deep
soils).
4-13
-------
For shallow soils, Alternatives S3 (excavation and recycling) and S4 (excava-
tion and biopiling) would equally provide the greatest protection of human health and the
environment. In both cases, contaminated soils would be removed (thereby eliminating
risks), but some contaminants would be released to the atmosphere during excavation. These
alternatives are very effective for treating soils with moderate to high risks, where immediate
removal is desirable. At OU 4, soil risks are moderate to low even under the most conserva-
tive residential exposure scenario. Under the current land use, there is little or no risk hi the
OU 4 shallow soils. Soil disposal issues would also need to be addressed with both Alterna-
tives S3 and S4. Alternative S2 (ICIR) would also be protective to human health, using land
use restrictions to prohibit contact with, or ingestion of the low risk contaminated shallow
soils. Intrinsic remediation of the soils will be monitored to evaluate contaminant reduction.
Land use restrictions will remain fully in place until cleanup levels are achieved. High
concentrations of heavy hydrocarbons at the ADS A may not degrade. Alternative SI (no
action) is the least protective, since there would be no restricted access to contaminated soils.
For deep soils, Alternative S5 (bioventing) would provide the greatest protec-
tion of human health and the environment, because contaminants would be broken down in
situ, thereby eliminating the potential for contaminant migration into the groundwater. Soils
would not be removed, so disposal concerns and short-term exposures would be minimal.
Bioventing may strip some contaminants from the soil into the vapor phase. The soil gas and
these contaminants would be released to the atmosphere. Bioventing is an effective alterna-
tive for the protection of human health, where active soil treatment is warranted due to the
risks the deep soils may pose to other media. Other than the threat the deep soils at the FTA
and ADSA pose as a potential contaminant source to groundwater, the deep OU 4 soils pose
no other risks without excavation. With Alternative S2, land use restrictions would prohibit
excavation of contaminated soil, thereby also eliminating most of the risk to humans. The
risk from the potential migration of contaminants into groundwater would still exist. Alter-
native SI is the least protective, since there would be no restrictions on excavation of con-
taminated soil.
4-14
-------
Compliance with ARARs
For groundwater, Alternative G3 (air sparging) would comply with applicable
or relevant and appropriate cleanup standards (ARARs). It is likely that this type of
treatment is unnecessary, however, since there is no current groundwater risk, and no
groundwater users. Alternative G4 (in situ bioremediation) would also comply. According
to the modeling results and additional studies conducted at OU 4, Alternative G2 (ICIR)
would eventually comply with ARARs, only the time to achieve these levels would be
increased. The estimated period of time for cleanup is 7-13 years. This is an appropriate
length of time, given that the current and future land uses do not include residential or
recreational uses. Alternative Gl (no action) would fail to meet the requirements since there
would be no way to confirm whether ARARs have been met.
For shallow soils, Alternatives S3 (excavation and recycling) and S4 (biopil-
ing) would both comply with ARARs. These alternatives would provide a rapid response for
the removal of soils posing a potential threat to human health and the environment.
Alternative S2 (ICIR) would eventually meet the standards, except possibly at the ADSA for
some substances (asphalt). Alternative SI (no action) would fail to meet the requirements
since there would be no way to confirm any reduction in contaminant levels.
For deep soils, Alternative S5 (bioventing) would comply with ARARs.
Alternative S2 (ICIR) would eventually meet the standards, except possibly at the ADSA and
FTA for some substances (high concentrations of heavy hydrocarbons at the ADSA; solvents
at the FTA). This alternative would also not address the need for removal of the potential
contaminant source for the FTA groundwater plume, or future groundwater contamination at
the ADSA. Alternative SI (no action) would fail to meet the requirements since there would
be no way to confirm any reduction in contaminant levels.
4-15
-------
4.4.2 Primary Balancing Criteria
Alternatives G2 through G4, and S2 through S5, will be the only alternatives
considered further in the comparative analysis. The no action alternatives (Gl and SI) are
not evaluated based on the primary balancing criteria or the modifying criteria, since these
did not meet the threshold criteria.
Long-Term Effectiveness and Permanence
This criterion has to do with long-term protection of human health and the
environment (reduction of risks), and adequacy and reliability of controls. Long-term man-
agement ("controls") would include a five-year review, land use restrictions, and annual
groundwater monitoring. For groundwater, Alternatives G3 and G4, as aggressive treat-
ments, would reduce contamination. Long-term management after the treated groundwater
met cleanup standards would not be needed. Alternative G2 would reduce future risk
through land use controls. Contamination is expected to be reduced permanently, but over a
longer period of time, therefore requiring additional long-term management. For all three
alternatives, decommissioning of the contaminant sources is essential to meeting this
criterion.
For shallow soils, Alternative S3 and S4 would reduce risks by removing con-
taminated soil and treating contaminants No long-term management would be needed after
the contaminated soils are removed and treated. Because of the low risks already associated
with the shallow soils at OU 4, aggressive risk reduction may not be necessary. Alternative
S2 would reduce risks by prohibiting contact or ingestion of the contaminated medium
through institutional controls. Alternative S2 may not meet the cleanup goals at the ADSA.
If Alternative S2 does not meet the cleanup goals, more aggressive treatments could be
implemented such as Alternatives S3, S4, or S5. Long-term management would include a
five-year review, land use restrictions, and soil sampling.
4-16
-------
For deep soils, Alternative S5 would reduce the risks associated with potential
soil excavation by breaking down contaminants through treatment. No long-term manage-
ment would be needed. Alternative S2 would also reduce risks through land use restrictions.
Long-term management would include a five-year review, land use restrictions, and soil
sampling.
Reduction in Toxicity, Mobility, and Volume Through Treatment
For groundwater, Alternative G4 would break down most contaminants,
thereby eliminating then" toxicity and volume. By extracting contaminated ground waiter, con-
taminant mobility would also be reduced. For sites with an elevated and immediate risk, a
groundwater extraction treatment would be the preferred alternative for quickly reducing the
effects of the contaminants. The groundwater risk at OU 4 is highest at Hangar 11. How-
ever, since this elevated risk is based on a hypothetical scenario and the source of con-
tamination for this plume is out of service, a groundwater treatment remedy may not be
necessary here or at the other OU 4 groundwater plumes. Alternative G3 would reduce con-
taminant toxicity and volume through treatment, however it is uncertain whether this
alternative would be effective given the soil and climatic conditions at OU 4. Alternative G2
will reduce toxicity and volume through intrinsic processes, but does not involve ground-
water treatment, so the time to achieve the reduction would be longer. Mobility would also
not be affected.
For shallow soils, Alternatives S3 and S4 would provide equal contaminant
reduction. With Alternative S4, biodegradation would permanently reduce the toxicity,
mobility, and volume of contaminants in the soil. With Alternative S3, the contaminated soil
would be removed from the base, thereby eliminating on-base contamination. The toxicity,
mobility, and volume of contamination would then be reduced by off-site treatment. Again,
due to the minimal risks associated with the shallow soils at OU 4, excavation as a treatment
option may not be necessary. With Alternative S2, the toxicity and volume of contaminants
would be reduced naturally through intrinsic remediation, but mobility would not be affected.
4-17
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However, this is not significant because the shallow soil fuel residues present at the OU 4
source areas are of low mobility. Alternative S2 does not treat the soils.
For deep soils, Alternative S5 would reduce the toxicity and volume of con-
taminated soils through biodegradation and volatilization; some contaminants could mobilize,
but the overall potential for deep soils to impact groundwater at sites where the deep soils
pose this risk would be greatly reduced. Alternative S2 would slowly reduce the toxicity and
volume of contaminants intrinsically, but would not affect mobility. The possibility of the
deep-soil contamination migrating to groundwater at the FTA, and ADSA, would not be
affected.
Short-Term Effectiveness
This criterion evaluates risks to workers, the community, and the environment
during the period of time until remedial action objectives are met. For groundwater,
Alternatives G3 and G4 are equally effective over the short term with minimal risks. Air
sparging (G3) may strip contaminants into the vapor phase and release them to the atmos-
phere, but concentrations should very low. Alternative G2 would have no significant short-
term risk, since implementation would result in an insignificant exposure. Similar worker
protection measures would be taken for each of these alternatives. Time until cleanup is
complete is listed for each site on Tables 4-2, 4-3, and 4-4. Remediation times for G3 and
G4 range from 3 to 9 years. For G2, remediation times range from 7 to 13 years.
For shallow soils, Alternative S2 was determined to be the most effective over
the short term, since implementation would require minimal exposure to the contaminated
soil. Alternatives S3 and S4 were also determined to be equally effective over the short
term. Excavation of soils would pose some risks to workers, but routine safety precautions
would make these risks negligible. Remediation times for Alternative S2 are the longest,
2 to 11 years. Alternatives S3 and S4 would be completed in a few weeks.
4-18
-------
For deep soils, Alternative S2 and S5 were determined to be equally effective
over the short term. With both alternatives, implementation would result in minimal expos-
ure of contamination to workers. Minor air emissions may result from bioventing activities
(S5), but concentrations should be very low. Alternative S2 would require 2 to 8 years.
Alternative S5 would be completed in less than 2 years.
Implementability
For ground water, Alternative G2 could be implemented easily, since it entails
the installation of long-term monitoring wells only, and would not significantly disturb base
operations. Alternatives G3 and G4 might interfere with some base operations near the
hangars, and require more substantial maintenance and operations over the life of the
systems. Alternative G3 is also a less well-proven technology, and potential heterogeneities
in the soil at OU 4 could cause preferential flow paths. With Alternative G4, cold weather
may cause aboveground pipes to freeze, winter maintenance would be problematic, and the
required equipment would require significant space.
For shallow soils, Alternative S2 could be implemented the most easily,
similar to groundwater. Only certain access restrictions and monitoring would be required.
With Alternatives S3 and S4, excavation would disturb base operations near the hangars.
Necessary equipment and specialists should be readily obtainable. Space for on-base
treatment would be required for Alternative S4. For Alternative S3, off-base disposal
problems may also complicate the success of this alternative.
For deep soils, Alternative S2 could be implemented the most easily, similar to
shallow soils. Only certain access restrictions and monitoring would be required. Alterna-
tive S5 could interfere with some base operations near the hangars. Necessary equipment
and specialists would be required.
4-19
-------
Cost
For all groundwater, Alternatives G4 ($8.8 million) and G3 ($3.7 million) cost
significantly more than Alternative G2 ($0.43 million).
For all soils, Alternatives S3 ($3.2 million) and S4 ($2.2 million) cost signifi-
cantly more than Alternative S5 ($0.39 million—deep soils only) and significantly more than
Alternative S2 ($0.39 million).
All costs are in present value.
4.4.3 Modifying Criteria
State Acceptance
The State of Alaska concurs with the USAF and the USEPA in the selection of
Alternatives G2 and S2 (ICIR) for groundwater and shallow soils at all source areas, and for
the deep soils at Hangar 15; and Alternative S5 (bioventing) for deep soils at the FTA,
Hangar 10/11, and the ADSA. The Air Force will investigate and implement other remedial
alternatives should the selected remedies prove to be unsuccessful at meeting the required
cleanup levels.
Community Acceptance
Based on the comments received during the public comment period, the public
has no preference of alternatives. One letter questioned the cost of Alternative S3. The
volume of soil to be handled is significantly greater than the in-place volume listed in the
Proposed Plan because ,of bulking during excavation and handling. Also, costs were esti-
mated using the RACER model for consistency between alternatives and there may be differ-
ences in actual bids received.
4-20
-------
Two letters were received which supported the selection of the preferred
alternatives.
4-21
-------
[This page intentionally left blank.]
-------
5.0 SELECTED REMEDY
The selected remedy for OU 4 is presented in Table 5-1, and includes
Alternatives G2 and S2 (institutional controls with intrinsic remediation - ICIR) for ground-
water and shallow soils at all source areas, and deep soils at Hangar 15; and Alternative S5
(bioventing) for deep soils at the Fire Training Area, Hangar 11, and the ADSA. The
selected remedy is hereafter referred to as Alternative G2/S2/S5. This alternative best meets
the nine CERCLA criteria. It protects human health and the environment, and complies with
ARARs. It is effective at reducing contamination both in the short term and long term, and
is implementable, cost-effective, and acceptable to the public and the State of Alaska. This
alternative provides an appropriate level of treatment to reduce risks and comply with
ARARs. Modeling showed that cleanup can occur within a reasonable time (13 years). The
known sources of contamination have been controlled, so they are no longer a threat. This
remedy will naturally degrade the residual contamination. Bioventing will increase the rate
of degradation in those areas that have soil contamination that may impact groundwater or
COCs that do not degrade easily.
Alternative G2/S2/S5 was selected because it best provides the following speci-
fic benefits at OU 4:
• Deep contaminated soils potentially contributing contaminants to
groundwater at the FTA, Hanger 11, and the ADSA are actively treated
with bioventing;
> At the FTA, some soil COCs have been detected in low levels
in the groundwater, thus demonstrating interaction between soil
and groundwater;
> At Hangar 11, contamination is found in soils close to the
groundwater table;
> At the ADSA, COCs include heavier hydrocarbons which are
more difficult to remediate intrinsically;
5-1
-------
Table 5-1
Selected Remedy for Operable Unit 4, Elmendorf AFB, AK
"~ fS
'-'; '
-. "• ' f *'r'f,
f % s
*Sfom*eA«»'' '
€Sffisftt'Cli»e$ffl**f«t^%'
"' ••'" -,
Capital -
' %' "'•.' V-
;- /Annt&f
- ' Fmeof.
-'*Wi& ' 7
x 'f»«»irtx:.<*» - %
^^^lune-^io ,s
, ',€fe»t«» -' "
^ /**»* V -
AJtarrostrre £2: Insfitafiori: Controls With Intratsic Remediallon (t€lR)£!&rGiiBdwater) "
FTA
Hangar 8
Hangar 10/1 1
Hangar 14
Hangar 15
Alternative Sir. Instltetiori Conte*
FTA (Shallow)
Hangar 8 (Shallow and Deep)
Hangar 10/11 (Shallow)
Hangar 14 (Shallow and Deep)
Hangar 15 (Shallow and Deep)
ADSA (Shallow)
24
13
10
9
8
rWitblHtriKri
20
4
12
4
8
15
19
10
8
7
6
S •• 5
Ecftemediat»F)E
9
3
6
3
3
8
188
72
79
48
40
t(iClR){Soas)
76 .
10
27
12
14
61
13
8
13
7
7
J ' 's v;
^ , '- '{'
8
11
2
4
3
4
Alternative SSt la Situ BJoveniing. (Deep Soils)
FTA
Hangar 10/11
ADSA
90
43
43
46
18
27
173
76
92
2
2
9
5-2
-------
Institutional controls will protect against potential risk to human health
by reducing the possibility that contaminated shallow soils will come in
contact with people until cleanup levels (ACM for fuels and fuel
constituents) are met; and
Institutional controls will protect against potential risk to human health
by reducing the possibility that contaminated shallow aquifer ground-
water will be consumed by people until cleanup levels (MCLs for fuel-
related constituents and HVOCs) are met.
Specific components of the selected remedy are illustrated in Figure 5-1 and
consist of the following:
Groundwater
• Institutional controls on land use and water use restrictions will restrict
access to the contaminated groundwater throughout OU 4 until cleanup
levels have been achieved.
• Groundwater will be monitored and evaluated semi-annually to assess
contaminant migration and timely reduction of contaminant concen-
trations by intrinsic remediation. This will include five-year reviews to
assess the protectiveness of the remedial action, as long as contamina-
tion remains above cleanup levels. A monitoring plan will be prepared
to address the details involved in sampling.
• All groundwater is expected to be cleaned up within thirteen years.
Soil
Institutional controls on land use will restrict access to the contaminated
shallow soils throughout OU 4 until cleanup levels have been achieved.
Deep soils at specified locations and depths at the FTA, the ADSA, and
Hangar 11 will be treated with bioventing to accelerate degradation of
contaminants in those locations. Deep soils at other source areas will
be allowed to degrade through intrinsic remediation.
Both shallow and deep soils will be monitored and evaluated bi-annual-
ly to assess contaminant migration and timely reduction of contaminant
5-3
-------
WEST
EAST
Institutional Controls
Bioventing
Bioventing
Monitoring and
Intrinsic Remediation
for Oroundwater and Soils
Monitoring and
Intrinsic Remediation
for Groundwater and Soils '*"
•:!•;: ;jiii;#H :&:*::::•:::::;: iilfci:
liiilipiiiiiiiiiiiii;
! Contaminated
^n^^M^ifi^^V^^iV^^^
Figure 5-1. A Schematic of Preferred Alternatives for Operable Unit 4,
Elmendorf AFB, AK
-------
concentrations by intrinsic remediation. This will include five-year
reviews to assess the protectiveness of the remedial action, as long as
contamination remains above cleanup levels.
• When concentrations in the bioventing areas are below cleanup levels,
bio venting will be discontinued. A monitoring plan will be prepared to
address the details involved in sampling.
• All soils are expected to be cleaned up within eleven years.
The remedy will be implemented after the Remedial Design has been complet-
ed. A treatability study for bioventing design is currently in progress. Bioventing will be
implemented until cleanup levels have been achieved. The actual timeframe for intrinsic
remediation at the other source areas is not known, but groundwater and soil modeling
predict cleanup levels will be achieved in 10 to 15 years. Groundwater and soil will both be
monitored to evaluate the progress of intrinsic remediation processes. - Further response
actions, coordinated with the regulatory agencies, may be considered if monitoring finds
unacceptable contaminant migration occurring, or unacceptable reduction in contaminant
concentrations through intrinsic remediation.
Because the remedy will result in contaminants remaining on-site above health
based levels, a review will be conducted within five years after commencement of remedial
action. The review will ensure that the remedy continues to provide adequate protection of
human health and the environment. The cleanup levels to be achieved though the selected
remedy for OU 4 are presented in Table 5-2.
5.1 Statutory Determinations
The selected remedy satisfies the requirements under Section 121 of CERCLA
to:
Protect human health and the environment;
5-5
-------
Table 5-2
Chemical-Specific ARARs for Groundwater and Soils, Operable Unit 4,
Elmendorf AFB, AK
f
f
j. -X
X^OC^RWWt- ••••
-
' f v * f '
ContatHiaaats ::of
.,.. .,.-e«»feera, - :
•• s
\ _.
XrSftXf {Quilt -•"' ''
* °"'C0JIC0irtF8^i0JftS:'"
Cleanup
•' jfed* V$X--*:- -•
Established
— I^AS&ii "•.
'
f ff "•
SomreeoJ
- '-
^[tttty^y^fn^t^ ff
f f A % f *
T?me(yr$)
Groundwater (jtgfL)
FTA
Hangar 14
Hangar 1 1
Hangar 8/10
Hangar 15/
Bldg. 43-410
1,1,1 -Trichloroethane
1 , 1 -Dichloroethene
1,2-Dichloroethane
Tetrachloroethene
Trichloroethene
1 ,2-Dichloroethene
Benzene
Benzene
Benzene
Ethylbenzene
Toluene
Benzene
Tetrachloroethene
Trichloroethene
242
13.7
12.1
40.5
74.7
741
398
207
2600
1360
5590
266
19.5
23
Soil (rag/kg)
FTA
Hangar 10/11
ADSA
DROb
GROe
DRO"
GROC
DROb
Jet Fuel
Xylene
GROC
2200
3710
4100
5900
110,000
13,000
110
15,600
200
7
6
6
6
70
5
5
5
700
1000
5
5
5
2000
1000
1000
2000
2000
2000
100
1000
MCL1
MCL1
MCL1
MCL1
MCL*
13
7
13
8
7
ACM"
ACM"
ACMd
2 (deep soils)
8 (shallow soils)
2 (deep soils)
2 (shallow soils)
2 (deep soils)
4 (shallow soils)
•MCL = Maximum Contamination Level; 40 CFR Part 131, and 18 ACC Chapter 70.0 lOa and d, 70.015 through 70.0110,18
AAC 80.070.
bDRO = Diesel Range Organics
'GRO = Gasoline Range Organics
JACM = Alaska Cleanup Matrix Level D, 18 AAC 78.315
Note-Soil contamination at Hangars 8, 14, and I5/Bldg. 43-410 was not above regulatory standard.
5-6
-------
• Comply with ARARs;
• Be cost effective; and
• Utilize permanent solutions and alternative treatment technologies to the
maximum extent practicable.
5.1.1 Protective of Human Health and the Environment
The selected remedy is protective of human health and the environment. The
current points of exposure are limited to surface soil. Risks are extremely low. Institutional
controls will protect against the potential risk by assuring that the contaminated soils will not
come in contact with people while intrinsic remediation is occurring. Deep soils pose no
health risk, but at the areas where they could pose a potential threat to groundwater, the soils
will be actively treated with bioventing.
Risks were calculated using assumptions regarding exposure pathways and the
tune receptors were exposed to the contaminants. Each exposure was estimated conserva-
tively in a manner which tends to overestimate the actual risk. Risk management decisions
were made considering the uncertainty hi the assumptions used in the risk assessment. At
OU 4, the shallow groundwater is not used and is not expected to be used in the future, so
existing risks and potential risks are significantly less than the worst-case risk.
There are no direct current receptors of groundwater hi OU 4. The known
sources of contamination have been removed. Deep soil hot spots will be remediated under
this selected remedy. Institutional controls will protect against the potential risk to human
health by ensuring that contaminated shallow aquifer groundwater will not be consumed by
people until cleanup levels (MCLs) are met. The time required to achieve MCLs is not
known, but could be as short as 10 to 15 years based on groundwater modeling results.
Modeling of contaminant flow at Elmendorf AFB showed that conditions are not expected to
deteriorate at OU 4. Over time, conditions will improve and the model predicts that cleanup
5-7
-------
objectives will be met by intrinsic remediation processes. A remediation period of 10 to 15
years is reasonable given current land use at the site.
5.1.2 Applicable or Relevant and Appropriate Requirements (ARARs)
Chemical-Specific ARARs - Chemical-specific cleanup levels for OU 4 are
identified in Table 5-2. The Maximum Contaminant Levels (MCLs) established for drinking
water under State and Federal laws are applicable to groundwater contaminants of cpncern at
OU 4 as a chemical-specific regulation. For petroleum contaminated soil that will be
remediated, soil cleanup level D from the Alaska Cleanup Matrix, 18 Alaska Administrative
Code (AAC) 78.315, is applicable.
Location-Specific ARARs — There are no specific ARARs which must be met
because of the location of the contamination and remedial actions at OU 4.
Action-Specific ARARs — The selected remedy will comply with those
ARARs applicable or relevant and appropriate to construction and operation of the bioventing
system, and to the monitoring activities conducted at all source areas. Action-specific
ARARs are identified in Table 5-3.
5.1.3 Cost Effectiveness
The remedy is the most cost effective of the alternatives because it affords
overall effectiveness proportional to its costs. Alternative S-5 (bioventing) was chosen for
the deep soils at the Fire Training Area, Hangar 11, and the ADSA because the soils in these
areas could act as continuing sources for the groundwater pollution in the shallow aquifer.
For these areas, Alternative S-5 will cost approximately $178,000 more than Alternative S-2;
however, Alternative S-5 will remediate the soils up to six years faster than Alternative S-2.
The additional protection that can be achieved by actively treating groundwater and soil in
5-8
-------
Table 5-3
Identification of Action-Specific ARARs, Operable Unit 4
Elmendorf AFB, AK
Standard,
Requirement, Criteria,
or Limitation
Citation
Description
Documentation
Clean Air Act - 42 USC Section 7401
National Primary and
Secondary Ambient Air
Quality Standards
40CFR
Part 50
Establishes standards for ambient
air quality to protect public health
and welfare.
Remedial actions must not
result in exceedence of
ambient air quality standards.
There could be air emissions
from bioventing.
5-9
-------
the other alternatives, provides only marginal increases in protection of human health and the
environment, with a cost several times higher than the selected remedy.
5.1.4 Utilization of Permanent Solutions and Alternative Treatment Technologies
to the Maximum Extent Practicable
The USAF, the State of Alaska, and the USEPA have determined that the
selected remedy represents the maximum extent to which permanent solutions and treatment
technologies can be used in a cost-effective manner at OU 4. Of those alternatives that are
protective of human health and the environment, and comply with ARARs, the USAF, the
State of Alaska, and the USEPA have determined that the selected remedy provides the best
balance of tradeoffs in terms of long-term effectiveness and permanence, reduction in
toxicity, mobility, or volume achieved through treatment, short-term effectiveness, imple-
mentability, cost (as discussed in the preceding section), and the statutory preference for
treatment as a principal element and considering State and community acceptance. The
selected remedy will permanently remove the contaminants through natural, biological break
down of the contaminants into harmless chemical compounds.
5.1.5 Preference for Treatment as a Principal Element
The selected remedy satisfies this statutory preference by using bioventing to
treat contaminated deep soils at source areas where soils may act as a continuing source for
groundwater contamination. Because of the substantial additional cost of actively treating
groundwater, the potential for intrinsic remediation within 13 years, and the fact that there
are no current receptors of groundwater, institutional controls and monitoring are a better
way of addressing groundwater contamination than active treatment. Intrinsic remediation
and institutional controls are used in areas where active treatment is impracticable.
5-10
-------
5.2 Documentation of Significant Changes
The selected remedy was the preferred alternative presented in the Proposed
Plan. No significant changes have been made.
In Table 5 of the Proposed Plan, the listing of S5-Bioventing as the preferred
alternative for shallow soils at Hangars 10/11 was a misprint. As discussed in the text of the
Proposed Plan, S2-ICIR was the preferred alternative for all shallow soils. The bioventing
alternative is applicable for deep soils only.
5-11
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PARTHI. RESPONSIVENESS SUMMARY
Public Input into the OU 4 Selected Remedy
The primary avenues of public input have been through the Proposed Plan and
public comment period. The Proposed Plan for OU 4 was issued to the public on April 11,
1995. This began a public comment period that ended on May 12, 1995. To encourage
*
public comment, the USAF inserted a pre-addressed, written comment form hi distributed
copies of the Proposed Plan. The comment forms were also distributed at the May 10, 1995
public meeting, held at the University of Alaska in Anchorage.
The public meeting to receive comments on the Proposed Plan was attended by
approximately 35 people, including sixteen representatives from the Restoration Advisory
Board (RAB). Oral comments were received from six members of the public. Prior to the
conclusion of the public comment period, a written comment was submitted by one
individual.
All comments received are documented in the administrative record file for the
site. A transcript of the public meeting is available for public review at the site information
repositories. The repositories are located at the Bureau of Land Management's Alaska
Resources Library and the University of Alaska at Anchorage's Consortium Library. Public
comments, relevant to OU 4 and/or the environmental restoration program at Elmendorf, are
presented below and have been paraphrased for greater clarity. This ROD is based on the
documents in the Administrative Record and comments received from the public.
Response to Written Public Comment:
Public Comment: The costs for soil excavation and recycling are too high.
USAF Response: Costs were developed for all alternatives using the RACER model to
provide a consistent data base for alternative comparison. The model
includes additional costs such as contingencies as a percentage of the
-------
total. Actual costs could vary by up to 50%. Also, the soil quantities
listed in the Proposed Plan were in-place soil volumes. Disturbed soil
volumes to be excavated and treated would be significantly increased
because of bulking.
Response to Oral Public Comments:
Public Comment 1: There was a concern that because the Anchorage area is subject to
earthquakes, a large earthquake could increase the risk of the public's
exposure to contaminants.
USAF Response: Elmendorf AFB is located on what is called a glacial outwash plain.
This is an area that consists of deep deposits of rocks, gravel, sand and
silts that have been transported to their present locations by the flow of
water from melting glaciers. An earthquake fault or split in the rock
will occur in the bed rock or large, continuous rock formations that lie
far beneath the outwash plain. Because the glacial outwash plain
consists of materials that easily shift and move, but do not shear or
separate during an earthquake, there is very little danger of increased
risk of exposure to contaminants due to an earthquake.
Public Comment 2: The OU 4 Proposed Plan separates the groundwater into shallow and
deep aquifers. It also separates the soil into shallow and deep soils.
Some of the deep soils are contaminated, yet the deep aquifer is listed
as uncontaminated. How can the deep soil be contaminated, yet the
deep aquifer be uncontaminated?
USAF Response: Two different measurements are used to determine deep soil and the
deep groundwater aquifer. For OU 4 soil from the ground surface to
five feet below the ground surface is called shallow soil. Soil deeper
than five feet below the ground surface is called deep soil. The
groundwater does not use the five foot below ground surface to distin-
-------
guish deep from shallow. The top of the shallow aquifer is approxi-
mately 50 feet below the ground surface, while the top of the deep
aquifer is approximately 140 feet below the ground surface.
Public Comment 3: The report says that modeling shows that groundwater contamination
will not migrate off-site. What are the limits of the site? Are they the
boundaries of Elmendorf?
USAF Response: This report is addressing OU 4 specifically. The site in this report
means that the groundwater contamination will not migrate outside the
boundaries of OU 4. The model shows that the contamination will not
migrate beyond the East-West runway, which is approximately half of
the distance between the source of the contaminants and Ship Creek.
Ship Creek is the closest migration path for the-contaminants to reach
human or environmental receptors.
Public Comment 4: Table 1 of the Proposed Plan for Remedial Action shows a maximum
concentration of 110,000 mg/kg for diesel in the asphalt drum storage
area (ADSA). This is over fifty times greater than the standard shown
in the same table. Shouldn't this be considered a high risk to health
and the environment?
USAF Response: The high concentration is shown for shallow soil in the ADSA. The
ADS A is located at the east end of the East-West Runway. Access to
this area is highly restricted because of the high noise level and safety
concerns from low flying aircraft. Normally we are more concerned
about shallow soils than deep soils, because human and animal recep-
tors are more likely to come into contact with these soils. However
because of its location, access to the ADSA is very restricted, so the
shallow soils here are not as great a concern as in other areas. Table 1
also shows that the deep soils at this area are contaminated with jet fuel
and gasoline. Because of the comparatively higher level of contamina-
-------
tion at the ADSA, and the possibility of these levels being sources that
could contaminate the groundwater in the future; we are proposing bio-
venting to more quickly remediate this contamination.
Public Comment 5: The proposed plan contains a table on human health risks. It lists
numbers like 4.2 x 10 "6. What do these numbers mean? Are they high
risk, medium risk or low risk?
USAF Response: The EPA normally establishes the threshold for taking action to be in
the range of one in ten thousand (1x10"*) to one hi a million (IxlO"6).
A result of 4.2 x lO'6 is on the borderline of where the EPA would
expect action to be taken. Note that these values are for residents
living full time on the site which is not allowed hi the area around
OU4.
Public Comment 6: Is there more in-depth information available than what is given hi the
Proposed Plan for Remedial Action?
USAF Response: Complete copies of the Remedial Investigation/Feasibility Study
(RI/FS) are available for the public to read at the Bureau of Land
Management Library and at the University of Alaska Anchorage
Library.
Public Comment 7: What is the basis for determining what alternatives are selected? Is the
decision driven solely by the money available?
USAF Response: Although costs are one of the factors used in evaluating alternatives, it
is only one of the nine factors considered. The factors considered in
selecting the alternatives to use are: protection of human health and the
environment; compliance with applicable or relevant and appropriate
requirements such as laws and government regulations; long term effec-
tiveness and permanence; reduction in toxicity, mobility or volume
-------
through treatment; short term effectiveness; implementability; cost;
state acceptance; and community acceptance. All nine factors are used
in determining the best alternatives to implement.
Public Comment 8: The proposed alternative calls for Institutional Controls with Intrinsic
Remediation in many areas. This would require monitoring of the
groundwater for a long period of time. Who will do the actual moni-
toring of the groundwater?
USAF Response: Taking samples and monitoring the groundwater would be accom-
plished by a civilian contractor working for the Air Force. We will
monitor the groundwater quality for around 15 years.
Public Comment 9: What body or group makes the final decision on what alternatives will
be implemented?
USAF Response: Making the decision is a two step process. After we receive and eval-
uate the comments on our proposed plan, the Air Force will select the
best alternatives for each area to implement. This is the first step.
Our decision is then sent to the State of Alaska and the U.S. EPA for
their review and concurrence. Once we have their concurrence, a final
record of decision documenting the selected alternatives to be used is
prepared. That record of decision will be signed by the EPA and the
Air Force.
Public Comment 10: How long will it take to go from the public comment period, where
we are now, to the final completion of the cleanup of OU 4?
USAF Response: The record of decision should be signed in late August of this year.
We will then need around 15 months to prepare the plans and specifi-
cations and hire a contractor to perform the work. Assuming that the
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proposed alternatives are the ones actually implemented, it will take up
to 15 years before the pollution has been completely remediated.
Public Comment 11: Fifteen years seems to be a long time to wait until the contamination is
finally remediated.
USAF Response: If this contamination were an immediate threat to life or health, the
Air Force would immediately begin fixing the problem using the
fastest and best methods possible. However, the contamination present
is not currently a threat to human health or the environment. It is
migrating very slowly. We have stopped the leaks and other sources
that were causing the pollution. Naturally occurring microorganisms
are presently breaking down the contaminants, and will continue to do
so until the contaminants are completely broken down. We are com-
mitted to long term monitoring of the site to ensure that the contami-
nation is not spreading beyond its predicted limits, and to ensure that
the biological breakdown of the contaminants is occurring.
Public Comment 12: Alaska is not the lower 48. Will the methods proposed work well in
the cold climate at Elmendorf? Have the proposed methods been used
on Elmendorf in the past?
USAF Response: Yes. We have used bioventing on Elmendorf for two and a half years
now and have had good results. Bioventing works well in the granular
soils that are underneath Elmendorf. Biopiles have also been used
successfully on the base.
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APPENDIX A
OU 4 ADMINISTRATIVE RECORD INDEX
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Appendix A
Index to OU 4 Documents in Administrative Record
DM
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