PB96-964507
EPA/ROD/R09-96/149
August 1996
EPA Superfund
Record of Decision:
Mather Air Force Base, Soil and Groundwater
Operable Units, Sacramento, CA
6/21/1996
-------
-------
Superfund Record of Decision
Final
Soil Operable Unit Sites and Groundwater
Operable Unit Plumes
Mather Air Force Base
Sacramento County, California
April 29, 1996
-------
-------
Table of Contents.
List of Figures x
List of Tables xi
List of Appendices xiii
List of Acronyms xiv
1.0 Introduction 1-1
1.1 Site Background 1-2
1.1.1 Soil OU Sites Selected for No Further Action 1-5
1.1.2 Petroleum Only Sites Selected for No Further Action Under
CERCLA (but remain to be closed under other regulations) ... 1-7
1.2 Signatures 1-9
2.0 Soil Operable Unit Sites Selected for Remedial Action 2-1
2.1 Declaration for the Soil Operable Unit Sites Selected for Remedial Action . 2-1
2.1.1 Site Name and Location 2-1
2.1.2 Statement of Basis and Purpose 2-1
2,1.3 Assessment of the Sites 2-1
2.1.4 Description of the Selected Remedy 2-2
2.1.5 Statutory Determinations 2-4
2.2 Decision Summary for Soil OU Sites Selected for Remedial Action ..... 2-4
2.2.1 Site Names, Location, and Description 2-4
2.2.2 Site History and Enforcement Activities 2-4
2.2.3 Highlights of Community Participation 2-6
2.2.4 Scope and Role of Response Action 2-6
2.2.5 Summary of Site Characteristics 2-6
2.2.5.1 Site 7/11 - "7100 Area" Disposal Site/Existing Fire
Protection Training Area 2-9
2.2.5.2 Site 13 - Drainage Ditch Number 1 2-10
2.2.5.3 Site 15 - Drainage Ditch No. 3 2-10
2.2.5.4 Site 20 - Sewage Treatment Plant 2-11
2.2.5.5 Site 37/39/54 - Building 3389/Hazardous Waste
Central Storage 2-11
RL/2-16-96/ES/1260005.AWS
11
-------
Table of Contents (Continued)
2.2.5.6 Site 56 - Oil/Water Separator 2989 2-12
2.2.5.7 Site 57 - Oil/Water Separator 7019 2-13
2.2.5.8 Site 59 - Oil/Water Separator 4251 2-13
2.2.5.9 Site 60 - Oil/Water Separator 6900 2-13
2.2.5.10 Site 62 - OWS 7110 and Jet Engine Test Cell 2-14
2.2.5.11 Site 65 Oil/Water Separator 6910 2-14
2.2.5.12 Site 69 - Open Burn Detonation Area 2-14
2.2.6 Summary of Site Risks 2-15
2.2.6.1 Human Health Risks 2-15
2.2.7 Description of Alternatives 2-21
2.2.7.1 Site 7/11 Remedial Alternative 2-21
2.2.7.2 Site 13 Remedial Alternatives 2-21
2.2.7.3 Site 15 Remedial Alternatives 2-22
2.2.7.4 Site 20 Remedial Alternatives 2-22
2.2.7.5 Site 37/39/54 Remedial Alternative 2-23
2.2.7.6 Site 56 Remedial Alternatives 2-23
2.2.7.7 Site 57 Remedial Alternatives 2-24
2.2.7.8 Site 59 Remedial Alternatives 2-24
2.2.7.9 Site 60 Remedial Alternatives 2-25
2.2.7.10 Site 62 Remedial Alternatives 2-25
2.2.7.11 Site 65 Remedial Alternatives 2-26
2.2.7.12 Site 69 Remedial Alternatives 2-26
2.2.8 Summary of Comparison Analysis of Alternatives 2-26
2.2.8.1 Overall Protection of Human Health and the
Environment 2-27
2.2.8.2 Compliance with ARARs 2-27
2.2.8.3 Long-Term Effectiveness and Permanence 2-28
2.2.8.4 Reduction of Toxicity, Mobility, or Volume 2-28
2.2.8.5 Short-Term Effectiveness 2-28
2.2.8.6 Implementability 2-28
2.2.8.7 Cost 2-28
2.2.8.8 State/Support Agency Acceptance 2-28
RL/2-16-96/ES/1260005.AWS U1
-------
Table of Contents (Continued)
2.2.8.9 Community Acceptance 2-31
2.2.9 The Selected Remedies 2-31
2.2.9.1 Site 7/11 - "7100 Area" Disposal Site/Existing Fire
Protection Training Area 2-31
2.2.9.2 Site 13 - Drainage Ditch Number 1 2-33
2.2.9.3 Site 15 - Drainage Ditch Number 3 2-36
2.2.9.4 Site 20 Sewage Treatment Plant 2-38
2.2.9.5 Site 37/39/54 - Building 3389/Hazardous Waste
Control Storage 2-39
2.2.9.6 Site 56 - Oil/Water Separator 2989 2-42
2.2.9.7 Site 57 - Oil/Water Separator 7019 2-43
2.2.9.8 Site 59 - Oil/Water Separator 4251 2-45
2.2.9.9 Site 60 - Oil/Water Separator 6900 2-46
2.2.9.10 Site 62 - Oil/Water Separator 7110 and
Jet Engine Test Cell (Facility 7099) 2-46
2.2.9.11 Site 65 - Oil/Water Separator 6910 2-48
2.2.9.12 Site 69 - Open Burn/Open Detonation Area 2-49
2.2.10 Statutory Determinations 2-51
3.0 Soil Operable Unit Sites Selected for No Further Action 3-1
3.1 Declaration for the Soil Operable Unit Sites Selected for
No Further Action 3-1
3.1.1 Site Name and Location 3-1
3.1.2 Statement of Basis and Purpose 3-1
3.1.3 Description of the No Further Action Decision 3-2
3.1.4 Summary of Site Risks 3-2
3.1.4.1 Human Health Risks 3-2
3.2 Decision Summary for Soil OU Sites Selected for No Further Action .... 3-2
3.2.1 Site Name, Location, and Description 3-2
3.2.2 Site History and Enforcement Activities 3-4
3.2.3 Highlights of Community Participation 3-4
3.2.4 Scope and Role of Response Action 3-4
RL/2-16-96/ES/1260005.AWS 1V
-------
Table of Contents (Continued)
3.2.4.1 Description of the "No Action" Alternative 3-4
3.2.5 Summary of Site Characteristics 3-4
3.2.5.1 Site 9 - Fire Department Training Area Number 2 . . 3-4
3.2.5.2 Site 10 - Fire Department Training Area Number 3 . 3-6
3.2.5.3 Site 14 - Drainage Ditch Number 2 3-6
3.2.5.4 Site 16 - Electron Tube Burial Site 3-6
3.2.5.5 Site 21 - Asphalt Rubble Storage Site 3-6
3.2.5.6 Site 22 - Asphalt Rubble Storage Site 3-6
3.2.5.7 Site 24 - 1983 JP-4 Spill and Refueling Apron .... 3-7
3.2.5.8 Site 26 - Building 10072, One Abandoned UST ... 3-7
3.2.5.9 Site 27 - Building 10060, One Abandoned UST ... 3-7
3.2.5.10 Site 28 - Building 16100, One Abandoned UST ... 3-7
3.2.5.11 Site 31 - Building 10090, One Abandoned UST ... 3-7
3.2.5.12 Site 33 - Building 3308, Six Abandoned USTs 3-8
3.2.5.13 Site 38 - Building 3388 3-8
3.2.5.14 Site 40 - Building 3875, One UST 3-8
3.2.5.15 Site 41 - Building 2995, Two USTs 3-8
3.2.5.16 Site 42 - Building 2898, One UST 3-9
3.2.5.17 Site 43 - Building 10150, Two Abandoned USTs .. 3-9
3.2.5.18 Site 44 - Building 8540, One UST 3-9
3.2.5.19 Site 45 - Building 7003, One UST 3-9
3.2.5.20 Site 46 - Building 8158, One UST 3-9
3.2.5.21 Site 48 - Building 10410, Two Abandoned USTs . . 3-9
3.2.5.22 Site 49 - Building 10450, One UST 3-10
3.2.5.23 Site 51 - Building 10030, One UST 3-10
3.2.5.24 Site 52 - Building 10400, One UST 3-10
3.2.5.25 Site 53 - Building 18501, One UST 3-10
3.2.5.26 Site 55 - OWS 7038 3-10
3.2.5.27 Site 58 - OWS 4771 3-10
3.2.5.28 Site 61 - OWS 6905 3-11
3.2.5.29 Site 63 - OWS 3321 and Two USTs 3-11
3.2.5.30 Site 64 - OWS 4120 3-11
RL/2-16-96/ES/1260005.AWS
-------
Table of Contents (Continued)
3.2.5.31 Site 66 - OWS 6915 3-11
3.2.5.32 Site A 3-12
3.2.5.33 Site C 3-12
3.2.5.34 Site E 3-12
3.2.5.35 Site F 3-12
3.2.5.36 Site G 3-12
3.2.5.37 Site H 3-13
3.2.5.38 Site I 3-13
4.0 Soil Operable Unit "Petroleum Only" Sites Selected for No Action Under
CERCLA (but which remain to be closed under other regulations) 4-1
4.1 Declaration for the Soil Operable Unit Petroleum Only Sites
Selected for No Action 4-1
4.1.1 Site Name and Location 4-1
4.1.2 Statement of Basis and Purpose 4-1
4.1.3 Description of the Selected Remedy 4-2
4.1.4 Declaration Statement 4-2
4.2 Decision Summary for Soil OU "Petroleum Only" Sites Selected
for No Action Under CERCLA (but which remain to be closed
under other regulations) 4-2
4.2.1 Site Name, Location, and Description 4-2
4.2.2 Site History and Enforcement Activities 4-4
4.2.3 Highlights of Community Participation 4-4
4.2.4 Scope and Role of Response Action 4-5
4.2.5 Summary of Site Characteristics 4-5
4.2.5.1 Site 19 - Fuel Tank Sludge Burial Site 4-5
4.2.5.2 Site 29/B - Fuel Spill at Petroleum Oil and ,
Lubricant Yard Number 4 4-6
4.2.5.3 Site 32 - Fuel Spill at Army/Air Force Exchange
Services Service Station 4-6
4.2.5.4 Site 34 - Fuel Spill at Family Housing Army/
Air Force Exchange Services Service Station 4-7
RL/2-16-96/ES/1260005.AWS V1
-------
Table of Contents (Continued)
4.2.5.5 Site 35 - Building 3226 - Four Abandoned USTs ... 4-7
4.2.5.6 Site 36 - Building 3286 4-7
4.2.6 Summary of Site Risks 4-7
4.2.6.1 Human Health Risks 4-8
4.2.7 Statutory Authority Finding 4-8
5.0 Groundwater Operable Unit Plumes Selected for Remedial Action 5-1
5.1 Declaration for the Groundwater Operable Unit Plumes Selected for
Remedial Action 5-1
5.1.1 Plume Name and Location 5-1
5.1.2 Statement of Basis and Purpose 5-1
5.1.3 Assessment of the Plume 5-1
5.1.4 Description of Selected Remedy 5-2
5.1.5 Statutory Determinations 5-3
5.2 Decision Summary for Groundwater OU Plumes Selected for
Remedial Action 5-4
5.2.1 Plume Name, Location, and Description 5-4
5.2.2 Site History and Enforcement Activities 5-4
5.2.3 Highlights of Community Participation 5-4
5.2.4 Scope and Role of Response Action 5-6
5.2.5 Summary of Site Characteristics 5-6
5.2.5.1 Main Base/SAC Industrial Area Groundwater
Plumes 5-6
5.2.5.2 Site 7 Groundwater Plume 5-8
5.2.5.3 Northeast Groundwater Plume 5-8
5.2.6 Summary of Site Risks 5-8
5.2.7 Description of Alternatives 5-9
5.2.7.1 Main Base/S AC Industrial Area Groundwater Plume
Remedial Alternatives 5-9
5.2.7.2 Site 7 Groundwater Plume Remedial Alternatives . . 5-9
RL/2-16-96/ES/1260005.AWS V11
-------
Table of Contents (Continued)
5.2.7.3 Northeast Ground water Plume Remedial
Alternatives 5-10
5.2.8 Summary of Comparison Analysis of Alternatives 5-10
5.2.8.1 Overall Protection of Human Health and
the Environment 5-12
5.2.8.2 Compliance with ARARs 5-12
5.2.8.3 Long-Term Effectiveness and Permanence 5-12
5.2.8.4 Reduction of Toxicity, Mobility, or Volume 5-12
5.2.8.5 Short-Term Effectiveness 5-12
5.2.8.6 Implementability 5-12
5.2.8.7 Cost 5-13
5.2.8.8 State/Support Agency Acceptance 5-13
5.2.8.9 Community Acceptance 5-13
5.2.9 The Selected Remedies 5-13
5.2.9.1 Main Base/SAC Industrial Area
Groundwater Plume 5-13
5.2.9.2 Site 7 Groundwater Plume 5-15
5.2.9.3 Northeast Groundwater Plume 5-17
5.2.10 Description of the Selected Remedies 5-18
5.2.10.1 Extraction Wells . 5-18
5.2.10.2 Pre-Treatment Unit 5-18
5.2.10.3 Air Stripping Tower and Blower 5-19
5.2.10.4 Post-Treatment Unit 5-19
5.2.10.5 Vapor Phase Carbon Adsorption System 5-20
5.2.10.6 Discharge of Treated Water 5-20
5.2.10.7 Affected Water Supply Wells 5-22
5.2.11 Performance Evaluations .- 5-23
5.2.12 Statutory Determinations 5-24
6.0 List of Applicable or Relevant and Appropriate Requirements and
To-Be-Considereds 6-1
6.1 Chemical-Specific ARARs and TBCs 6-2
RL/2-16-96/ES/1260005.AWS
Vlll
-------
Table of Contents (Continued)
6.1.1 Federal Chemical-Specific ARARs and TBCs 6-2
6.1.1.1 Soils 6-2
6.1.1.2 Surface Waters 6-3
6.1.1.3 Groundwater 6-3
6.1.2 State Chemical-Specific ARARs and TBCs 6-4
6.1.2.1 Soils 6-4
6.1.2.2 Surface Waters 6-4
6.1.2.3 Groundwater 6-4
6.2 Location-Specific ARARs and TBCs 6-9
6.2.1 Federal Location-Specific ARARs 6-10
6.2.2 State Location-Specific ARARs 6-10
6.3 Action-Specific ARARs and TBCs 6-12
6.3.1 Federal ARARs 6-12
6.3.1.1 Other Federal Regulations 6-33
6.3.2 State ARARs and TBCs 6-33
6.3.2.1 State Air ARARs 6-33
6.3.2.2 State Groundwater and Soil ARARs 6-34
6.3.2.3 State Solid Waste ARARs 6-38
6.3.2.4 Other State Regulations 6-39
6.3.2.5 State Requirements for Ex Situ Soil Bioremediation
Facility 6-40
7.0 Responsiveness Summary 7-1
8.0 References 8-1
RL/2-16-96/ES/1260005.AWS
IX
-------
List of Figures.
Figure Title Page
1-1 Site Vicinity Map 1-3
2-1 Soil OU Sites Selected for Remedial Action 2-5
3-1 Soil OU Sites Selected for No Further Action 3-3
4-1 Soil OU "Petroleum Only" Sites 4-3
5-1 Groundwater OU Plumes 5-5
RL/2-16-96/ES/1260005.AWS
-------
List of Tables.
Table Title Page
Table 1-1. Selected Remedial Alternatives for the Soil Operable Unit Sites
Selected for Remedial Action 1-6
Table 1-2. Selected Remedial Alternatives for the Ground water Operable Unit Plumes . . 1-7
Table 2-1. Remedial Alternatives for the Soil Operable Unit Sites Selected
for Remedial Action 2-2
Table 2-2. Previous Investigations at the Soil Operable Unit Sites Selected
for Remedial Action 2-7
Table 2-3. Estimated Areas and Volumes - Sediments . 2-8
Table 2-4. Estimated Areas and Volumes - Surface Soils 2-8
Table 2-5. Estimated Areas and Volumes - Subsurface Soils 2-8
Table 2-6. Site 7/11 Remedial Alternatives 2-21
Table 2-7. Site 13 Remedial Alternatives 2-22
Table 2-8. Site 15 Remedial Alternatives 2-22
Table 2-9. Site 20 Remedial Alternatives 2-22
Table 2-10. Site 37/39/54 Remedial Alternatives 2-23
Table 2-11. Site 56 Remedial Alternatives 2-23
Table 2-12. Site 57 Remedial Alternatives 2-24
Table 2-13. Site 59 Remedial Alternatives 2-24
Table 2-14. Site 60 Remedial Alternatives 2-25
Table 2-15. Site 62 Remedial Alternatives 2-25
Table 2-16. Site 65 Remedial Alternatives 2-26
Table 2-17. Site 69 Remedial Alternatives 2-26
Table 2-18. Comparative Analysis of Soil Operable Unit Remedial Alternatives 2-29
Table 2-19. Site 7/11 Cleanup Levels 2-33
Table 2-20. Site 13 Cleanup Levels 2-34
Table 2-21. Site 15 Cleanup Levels 2-36
Table 2-22. Site 20 Cleanup Levels 2-39
Table 2-23. Sites 37/39/54 Cleanup Levels 2-41
Table 2-24. Site 56 Cleanup Levels 2-42
Table 2-25. Site 57 Cleanup Level 2-45
RL/2-16-96/ES/1260005. AWS
XI
-------
Table 2-26. Site 59 Cleanup Levels 2-45
Table 2-27. Site 60 Cleanup Levels 2-46
Table 2-28. Site 62 Cleanup Levels 2-47
Table 2-29. Site 65 Cleanup Levels 2^9
Table 2-30. Site 69 Cleanup Levels 2-50
Table 3-1. Previous Investigations at the No Further Action Sites 3-5
Table 4-1. Previous Investigations at the Soil Operable Unit "Petroleum Only" Sites ... 4-4
Table 4-2. Estimated Areas and Volumes - Subsurface Soils 4-6
Table 5-1. Selected Remedial Alternatives for the Ground water OU Plumes 5-3
Table 5-2. Previous Investigations at the Groundwater Operable Unit Sites 5-4
Table 5-3. Estimates of Volume - Groundwater 5-7
Table 5-4. Main Base/SAC Industrial Plume Remedial Alternatives 5-9
Table 5-5. Site 7 Plume Remedial Alternatives 5-10
Table 5-6. Northeast Plume Remedial Alternatives 5-10
Table 5-7. Comparative Analysis of Groundwater Remedial Alternatives 5-11
Table 5-8. Main Base/SAC Industrial Area Plume Cleanup Levels 5-15
Table 5-9. Site 7 Plume Cleanup Levels 5-16
Table 5-10. Northeast Plume Cleanup Levels 5-18
Table 6-1. Chemical-Specific TBCs for Surface Water 6-3
Table 6-2. Chemical-Specific ARARs and TBCs for Sediments 6-5
Table 6-3. Chemical-Specific TBCs for Surface Soils 6-6
Table 6-4. Chemical-Specific TBCs for Subsurface Soils 6-8
Table 6-5. Chemical-Specific ARARs and TBCs for Drinking and Groundwater 6-9
Table 6-6. Action Specific ARARs 6-13
Table 6-7. Groundwater Discharge Treatment Standards 6-36
Table 6-8. Maximum Total or Leachable Constituent Concentrations 6-43
RL/2-16-96/ES/1260005.AWS
Xll
-------
List of Appendices
Appendix Title Page
A Administrative Record Index for Soil Operable
Unit Sites and Groundwater Operable Unit Plumes,
Mather Air Force Base, Sacramento County, California A-1
RL/2- 16-96/ES/1260005. A WS
xm
-------
List of Acronyms.
AC&W
AFB
AGE
ARAR
ASC
AST
ATC
AWQC
bis
BTEX
CCR
CERCLA
CFR
COC
COPC
CVR
CVRWQCB
D.I.
DCE
DLM
DISC
DWR
ESD
FFS
FR
FS
gpm
HWCL
IRP
JETC
JP-4
LCRS
Aircraft Control and Warning
Air Force Base
Aerospace Ground Equipment
Applicable or Relevant and Appropriate Requirement
Additional Site Characterization
aboveground storage tank
Air Training Command
Ambient Water Quality Criteria
below land surface
benzene, toluene, ethylbenzene, and xylenes
California Code of Regulations
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
contaminant of concern
contaminant of potential concern
Central Valley Region
Central Valley Regional Water Quality Control Board
deionized
dichloroethene
Designated Level Methodology
Department of Toxic Substances Control
Department of Water Resources
Explanation of Significant Difference
Focused Feasibility Study
Federal Register
feasibility study
gallons per minute
Hazardous Waste Control Law
Installation Restoration Program
jet engine testing cell
jet propellant fuel
leachate collection and removal systems
RU10-95/ES/1260005.AWS
XIV
-------
List of Acronyms (Continued).
MBRA
MCL
mg/kg
mg/L
NCP
NPL
OU
OWS
PAH
PCB
PCE
POL
POTW
ppm
PTU
PVC
RCRA
RI
ROD
SAC
SARA
SIP
SMAQMD
SVE
SWRCB
TBC
TCE
TDL
TPH
TSCA
UCL
USAF
USEPA
Mather Baseline Risk Assessment
maximum contaminant level
milligrams per kilogram
milligrams per liter
National Contingency Plan
National Priorities List
operable unit
oil/water separator
polycyclic aromatic hydrocarbon
polychlorinated biphenyl
perchloroethene (tetrachloroethene)
petroleum, oil, and lubricant
publicly owned treatment works
parts per million
post-treatment unit
polyvinyl chloride
Resource Conservation and Recovery Act
remedial investigation
Record of Decision
Strategic Air Command
Superfund Amendments and Reauthorization Act of 1986
State Implementation Plan
Sacramento Metropolitan Air Quality Management District
soil vapor extraction
State Water Resources Control Board
to-be-considered
trichloroethene
total designated level
total petroleum hydrocarbons
Toxic Substance Control Act
upper confidence level
United States Air Force
United States Environmental Protection Agency
RL/10-95/ES/1260005.AWS
XV
-------
List of Acronyms (Continued).
UST underground storage tank
WDR Waste Discharge Requirement
WET waste extraction test
WQG water quality goal
yd3 cubic yards
KL/10-95/ES/1260005.AWS XVI
-------
-------
1.0 Introduction
This decision document presents the selected remedial actions for the Soil Operable Unit (OU)
Sites and Groundwater OU Plumes, at the formerly active Mather Air Force Base (AFB),
Sacramento County, California. The selected remedial actions were 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) and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). These decisions, documented herein, are based on the information
contained in the Administrative Record File for the subject sites and plumes. The
Administrative Record Index (Appendix A) identifies documents that were considered or relied
upon to make these decisions.
The purpose of this Record of Decision (ROD) is to decide the appropriate level of
remediation necessary to protect human health and the environment, and determine what
requirements are applicable or relevant and appropriate requirements (ARARs) based on the
groundwater beneficial use designation and site-specific conditions.
This ROD has been divided into seven sections which specifically address the range of selected
remedial actions for the Soil OU sites and Groundwater OU plumes. These seven sections
are:
Section 1.0 - Introduction:
This section presents a summary of the selected remedial alternatives, as
well as signatures of concurrence by the United States Air Force
(USAF), United States Environmental Protection Agency (USEPA), and
the State of California.
Section 2.0 - Soil OU Sites Selected for Remedial Action:
This section of the ROD documents the remedial actions selected for soil
sites where cleanup is warranted.
Section 3.0 - Soil OU Sites Selected for No Further Action:
This section of the ROD documents the decision that no action is
warranted at these soil sites since conditions pose no current or potential
threat to human health or the environment.
RL/2-16-96/ES/1260005.AWS
1-1
-------
• Section 4.0 - Soil OU "Petroleum Only" Sites Selected for No Action Under
CERCLA (but remain to be closed under other regulations):
This section of the ROD documents the decision that no action is
warranted under CERCLA. since CERCLA does not provide the
appropriate legal authority to undertake a remedial action at these soil
sites. The no action decision does not constitute a finding that adequate
protection has been achieved at the sites. Cleanup alternatives have been
developed and will be implemented under the Resource Conservation
and Recovery Act (RCRA) Subtitle I, other appropriate State of
California regulations, and the Defense Environmental Restoration
Program.
• Section 5.0 - Groundwater OU Plumes Selected for Remedial Action:
This section of the ROD documents the remedial actions for the
groundwater plumes.
• Section 6.0 - Listing of ARARs:
This section describes all federal and state ARARs required to be
complied with under this ROD.
• Section 7.0 - Responsiveness Summary:
This section contains comments received during the public comment
period and responses to these comments.
Each section is addressed in its entirety in this ROD. The Soil OU sites and Groundwater OU
plumes selected for remedial action (Sections 2.0 and 5.0) are the main focus of this ROD.
This ROD addresses all compliance requirements under CERCLA. Any CERCLA sites at
Mather AFB not addressed in this ROD, or previous Mather AFB RODs, will be addressed in
the Final OU ROD.
1.1 Site Background
The formerly active Mather AFB is located in the Central Valley region of northern California
hi Sacramento County, approximately ten miles east of downtown Sacramento, California and
due south of unincorporated Rancho Cordova, California, as shown on Figure 1-1.
Figure 1-1. The base is due south of U.S. Highway 50, a major highway connecting
Sacramento and South Lake Tahoe. The formerly active base encompassed approximately
5,845 acres at the time of closure (129 acres of easements) in an unsurveyed part of Township
8 North, Ranges 6 East and 7 East. Mather AFB was constructed in 1918 and its primary
mission was as a flight training school. The base was decommissioned under the Base Closure
and Realignment Act on September 30, 1993.
RL/2-16-96/ES/1260005.AWS
1-2
-------
Figure 1-1. Site Vicinity Map
PREPARED FOR
MATHER AIR FORCE BASE
SACRAMENTO. CALIFORNIA
INTERNATIONAL
TECHNOLOGY
CORPORATION
RL/10-95/ES/1260005.AWS
-------
Contamination exists at Soil OU sites and Groundwater OU plumes as a result of past USAF
operations conducted between 1918 and 1993. The Soil OU is comprised of contaminated
soils associated with waste disposal pits, oil/water separators (OWS), gas stations,
underground storage tanks (USTs), fire training areas, and other miscellaneous sites. The
Groundwater OU consists of contaminated groundwater plumes beneath and within the
immediate vicinity of the base with the exception of the Aircraft Control and Warning
(AC&W) OU plume. The main sources of contamination at the Soil OU sites and
Groundwater OU plumes include industrial activities, equipment maintenance, fire suppression
training, and fuels storage and delivery.
Installation Restoration Program (IRP) activities at the formerly active base have been
conducted since 1982. These previous investigations have confirmed the presence of volatile
organic compounds and other hydrocarbons at several of the IRP sites. Based on this, the
entire base was proposed for listing on the Superfund (CERCLA) National Priorities List
(NPL) in July 1989, and was placed on the NPL on November 21, 1989. In July 1989, the
USAF, the USEPA, and the State of California signed a Federal Facility Agreement under
CERCLA Section 120 to ensure that environmental impacts from past and present operations
are thoroughly investigated and appropriate cleanup actions are taken to protect human health,
welfare, and the environment. The Federal Facility Agreement sets enforceable deadlines for
documents, defines roles and responsibilities of each signatory party, and provides a vehicle
for dispute resolution. The USAF is the owner of the site, the principal responsible party, and
lead agency for conducting investigative and cleanup activities. There have been no CERCLA
enforcement actions at the Soil OU sites or Groundwater OU plumes.
The Group 2 Sites Remedial Investigation (RI) Report [IT 1992a], the Group 3 Sites Technical
Memorandum [IT 1993a], and the Additional Field Investigation Report [IT 1994a] became
available to the public at the Mather Environmental Management Office in 1993 and 1994.
The Groundwater OU and Soil OU Focused Feasibility Study (FFS) Report [IT 1995a] became
available to the public in 1995. Each of these documents and the Proposed Plan for the
Groundwater OU Plumes and Soil OU Sites [IT 1995b] are part of the Administrative Record
File and are available for review at the following information repositories:
• the Environmental Management Office, Mather AFB;
• the Sacramento Central Library; and
• the Rancho Cordova Community Library.
RL/2-16-96/ES/1260005.AWS
1-4
-------
Formal request for public comment on the Proposed Plan [IT 1995b] and FFS Report [IT 1995a]
was published in the Sacramento Bee on May 1, 1995.
The public comment period extended from May 8, 1995 through June 7, 1995, to afford the public
a chance to comment on the Proposed Plan and the supporting RI/Feasibility Study (FS) reports.
A public meeting was held at Mather AFB (Building 2460) on May 18, 1995. Representatives
from the USAF, the USEPA Region IX, the California Regional Water Quality Control Board,
and the California Department of Toxic Substances Control (DTSC) were present at the meeting.
Representatives from the USAF and regulatory agencies answered questions about the Soil OU
sites and Groundwater OU plumes and the remedial alternatives under consideration. The
Responsiveness Summary, Section 7.0 of this ROD, contains comments received during the public
comment period and responses to these comments.
An informal dispute was invoked concerning the cleanup of VOCs in the vadose zone. The
parties to the FFA resolved the dispute as reflected in Sections 2.2.9.1 (Site 7/11), 2.2.9.5 (Site
37/39/54), and 2.2.9.7 (Site 57). The resolutions are negotiated solutions that are not generally
applicable to other sites except those at this facility.
The USAF, the USEPA Region IX, and the State of California concur with the selected remedial
actions (which are presented in Tables 1-1 and 1-2 and detailed in Sections 1.1.1 and 1.1.2) and
statutory determinations for each of the separate sections of this ROD. Concurrence by the parties
is indicated by the signatures in Section 1.2 of this ROD.
1.1.1 Soil OU Sites Selected for No Further Action
Cleanup options were not developed for sites which were previously clean-closed or recommended
for clean-closure by Sacramento County (i.e., USTs already removed) or for which no
contaminants of concern (COCs) were identified. Based on the human health risk assessment, all
the sites have cancer risks within or below the acceptable range of 1 x 10^ to 1 x 10"6 and
non-cancer risks less than a hazard index of 1.0 in their current state. Therefore, cleanup or
further investigative activities is not warranted. These no further action sites include: Sites 9,
10, 14, 16, 21, 22, 24, 26, 27, 28, 31, 33, 38, 40, 41, 42, 43, 44, 45, 46, 48, 49, 51, 52, 53,
55, 58, 61, 63, 64, 66, A, C, E, F, G, H, and I.
RL/2-16-96/ES/1260005.AWS
1-5
-------
Table 1-1. Selected Remedial Alternatives for the Soil Operable Unit Sites
Selected for Remedial Action
Selected
Remedial
Alternative
Description
7.3*
Filling in the depression at Site 7 to grade with on-base soils; hi situ bioremediation
and possibly soil vapor extraction (SVE) of the contaminated shallow and deep soils at
Sites 7 and 11; installation of a landfill cover at Site 7 as appropriate, and groundwater
monitoring if contamination remains at the site that threatens groundwater quality.
13.3
Excavation and transportation of the contaminated ditch sediments and surface soils to
the on-base ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
site that threatens groundwater quality.
15.3
Excavation and transportation of the contaminated ditch sediments to the on-base
ex situ bioremediation facility for treatment and on-base disposal as appropriate after
treatment and surface water monitoring if contamination remains at the site that
threatens surface water quality.
20.2
Excavation and transportation of the contaminated shallow subsurface soils to the on-
base ex situ bioremediation facility for treatment and on-base disposal as appropriate
after treatment and groundwater monitoring if contamination remains at the site that
threatens groundwater quality.
37.2**
Excavation and transportation of the contaminated surface soils to the on-base ex situ
bioremediation facility for treatment and on-base disposal as appropriate after
treatment; in situ bioremediation and possibly SVE of the contaminated shallow and
deep subsurface soils at Sites 37, 39, and 54; and groundwater monitoring if
contamination remains at the site that threatens groundwater quality.
56.3
Excavation and transportation of the contaminated surface soils and shallow subsurface
soils to the on-base ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
site that threatens groundwater quality.
57.3
SVE of the contaminated shallow and deep subsurface soils and groundwater
monitoring if contamination remains at the site that threatens groundwater quality.
59.2
Excavation and transportation of the contaminated shallow subsurface soils to the on-
base ex situ bioremediation facility for treatment and on-base disposal as appropriate
after treatment and groundwater monitoring if contamination remains at the site that
threatens groundwater quality.
60.2
Excavation and transportation of the contaminated shallow subsurface soils to the on-
base ex situ bioremediation facility for treatment and on-base disposal as appropriate
after treatment and groundwater monitoring if contamination remains at the site that
threatens groundwater quality.
62.3
Excavation and transportation of the contaminated surface soils and shallow subsurface
soils to the ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
sites that threatens groundwater quality.
RL/2-16-96/ES/1260005.AWS
1-6
-------
Table 1-1. Selected Remedial Alternatives for the Soil Operable Unit
Sites Selected for Remedial Action (Continued)
Selected
Remedial
Alternative
Description
65.3
Excavation and transportation of the contaminated surface soils to an approved off-base
facility for disposal; excavation and transportation of the contaminated shallow
subsurface soils to the on-base ex situ bioremediation facility for treatment and on-base
disposal as appropriate after treatment and groundwater monitoring if contamination
remains at the site that threatens groundwater quality.
69.2
Excavation and transportation of the contaminated sediments and surface soils for on-
base disposal as appropriate and surface water monitoring as appropriate if
contamination remains at the site that threatens surface water quality.
This remedial alternative applies to Sites 7/11.
This remedial alternative applies to Sites 37/39/54.
Table 1-2. Selected Remedial Alternatives for the Groundwater Operable Unit Plumes
Selected
Remedial
Alternative
Description
Main/SAC.2
Extraction of the contaminated groundwater with treatment by air stripping and injection
of the treated groundwater back into the aquifer (alternative means of groundwater
discharge may be implemented) and groundwater monitoring. In addition, carbon will
be utilized to adsorb and treat the off-gas from the air stripper, if appropriate.
SP7.2
Extraction of the contaminated groundwater with treatment by air stripping and injection
of the treated groundwater back into the aquifer (alternative means of groundwater
discharge may be implemented) and groundwater monitoring. In addition, carbon will
be utilized to adsorb and treat the off-gas from the air stripper, if appropriate.
Selected
Alternative
Long-Term Groundwater Monitoring and Land-Use Restrictions
1.1.2 Petroleum Only Sites Selected for No Further Action Under CERCLA (but remain
to be closed under other regulations)
A "no action" decision is the selected remedy for the "petroleum only" sites based on the lack
of statutory authority under CERCLA. The "petroleum only" sites include: Sites 19, 29/B,
32, 34, 35, and 36. Additionally, based on the human health risk assessment, all cancer risks
are within or below the acceptable range of 1 x 10^ to 1 x 10"6 and a non-cancer risk less than
RL/2-16-96/ES/1260005.AWS
1-7
-------
a hazard index of 1.0 in their current state. However, these sites do not meet criteria for
closure under RCRA Subtitle I and other applicable State of California regulations.
Regulatory oversight will be provided by CVRWQCB and possibly Sacramento County.
RL/2-16-96/ES/1260005.AWS
1-8
-------
1.2 Signatures
/
Alan K. Olsen / Date
Director, Air Force Base Conversion Agency
U.S. Air Force
Julie Anderson Date
Director, Federal Facilities Cleanup Office, Region IX
U.S. Environmental Protection Agency
• //
Anthony J. LanQis, CP. E. Date
Chief, Northern California Operations
Office of Military Facilities
Department of Toxic Substances Control
California Environmental Protection Agency
RL/2-16-96/ES/1260005.AWS
1-9
-------
-------
2.0 Soil Operable Unit Sites Selected for Remedial Action
2.1 Declaration for the Soil Operable Unit Sites Selected for Remedial Action
Statutory Preference for Treatment as a
Principal Element is Met
and a Five-year Review is Required at those Soil OU
Sites Selected for Remedial Action Under CERCLA
2.7. 7 Site Name and Location
Soil OU Sites (IRP Sites) Selected for Remedial Action
Mather AFB (a NPL Site)
Sacramento County, California
2. 7.2 Statement of Basis and Purpose
The Soil OU sites were investigated under the Mather IRP and are described and evaluated in
the RI/FS documents. This decision document presents the selected remedial actions for the
Soil OU sites for which remedial action is warranted at the formerly active Mather AFB.
These sites include: Sites 7/11 - "7100 Area" Disposal Site/Existing Pure Protection Training
Area, Site 13 - Drainage Ditch Number 1, Site 15 - Drainage Ditch Number 3, Site 20 -
Sewage Treatment Plant, Sites 37/39/54 - Building 3389/Hazardous Waste Control Storage
Facility, Site 56 - OWS 2989, Site 57 - OWS 7019, Site 59 - OWS 4251, Site 60 - OWS 6900,
Site 62 - Jet Engine Test Cell (Facility 7099) and OWS 7110, Site 65 - OWS 6910, and Site 69
- Open Burn/Open Detonation Area. These remedial actions were chosen in accordance with
CERCLA, as amended by SARA, and to the extent practicable, the NCP. These decisions are
based on the Administrative Record File for these sites.
The USEPA Region IX and the State of California concur with the selection of remedial
alternatives for each of the Soil OU sites.
2.7.3 Assessment of the Sites
Contamination exists at these Soil OU sites as a result of past US AF operations conducted
between 1918 and 1993.
RL/2-16-96/ES/1260005.AWS
2-1
-------
Actual or threatened releases of hazardous substances from these sites, if not addressed by
implementing the response actions selected in this section of the ROD, may present an
imminent and substantial endangerment to human health, welfare, or the environment.
2.1.4 Description of the Selected Remedy
This section of the ROD addresses remedies related to contamination of the soils at Sites 7/11,
13, 15, 20, 37/39/54, 56, 57, 59, 60, 62, 65, and 69.
Based on the human health risk assessment, all cancer risks are within or below the acceptable
range of 1 x 10"4 to 1 x 10"6 and all non-cancer risks have a hazard index of less than 1.0 in
their current state, except for Sites 56, 62, and 69 which have an estimated current and future
cancer risk greater than 1 x 10^. In addition, an ecological risk exists at Sites 13, 15, 20, 62,
and 69. The selected remedies at the Soil OU sites will be instituted to reduce risk to human
health, and/or reduce the risk to ecological receptors, and/or for the protection of
groundwater/surface water quality.
Table 2-1 provides the major components of the selected remedy for each of the Soil OU sites.
Table 2-1. Remedial Alternatives for the Soil Operable Unit Sites Selected
for Remedial Action
Selected
Remedial
Alternative
Description
7.3*
Filling the Site 7 depression to grade with on-base soils; in situ bioremediation and
possibly soil vapor extraction (SVE) of the contaminated shallow and deep soils at Sites 7
and 11; installation of a landfill cover at Site 7 as appropriate, and groundwater
monitoring if contamination remains at the site that threatens groundwater quality.
13.3
Excavation and transportation of the contaminated ditch sediments and surface soils to the
on-base ex situ bioremediation facility for treatment and on-base disposal as appropriate
after treatment and groundwater monitoring if contamination remains at the site that
threatens groundwater quality.
15.3
Excavation and transportation of the contaminated ditch sediments to the on-base ex situ
bioremediation facility for treatment and on-base disposal as appropriate after treatment
and surface water monitoring if contamination remains at the site that threatens surface
water quality.
20.2**
Excavation and transportation of the contaminated shallow subsurface soils to the on-base
ex situ bioremediation facility for treatment and on-base disposal as appropriate after
treatment and groundwater monitoring if contamination remains at the site that threatens
groundwater quality.
RL/2-16-96/ES/1260005.AWS
2-2
-------
Table 2-1. Remedial Alternatives for the Soil Operable Unit Sites Selected
for Remedial Action (Continued)
Selected
Remedial
Alternative
Description
37.2***
Excavation and transportation of the contaminated surface soils to the on-base ex situ
bioremediation facility for treatment and on-base disposal as appropriate after treatment;
in situ bioremediation and possibly SVE of the contaminated shallow and deep subsurface
soils at Sites 37, 39, and 54; and groundwater monitoring if contamination remains at the
site that threatens groundwater quality.
56.3
Excavation and transportation of the contaminated surface soils and shallow subsurface
soils to the on-base ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
site that threatens groundwater quality .
57.3
Soil vapor extraction of the contaminated shallow and deep subsurface soils and
groundwater monitoring if contamination remains at the site that threatens groundwater
quality.
59.2
Excavation and transportation of the contaminated shallow subsurface soils to the on-base
ex situ bioremediation facility for treatment and on-base disposal as appropriate after
treatment and groundwater monitoring if contamination remains at the site , that threatens
groundwater quality.
60.2
Excavation and transportation of the contaminated shallow subsurface soils to the on-base
ex situ bioremediation facility for treatment and on-base disposal as appropriate after
treatment and groundwater monitoring if contamination remains at the site , that threatens
groundwater quality.
62.3
Excavation and transportation of the contaminated surface soils and shallow subsurface
soils to the ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
sites that threatens groundwater quality.
65.3
Excavation and transportation of the contaminated surface soils to an approved off-base
facility for disposal; excavation and transportation of the contaminated shallow subsurface
soils to the on-base ex situ bioremediation facility for treatment and on-base disposal as
appropriate after treatment and groundwater monitoring if contamination remains at the
site that threatens groundwater quality.
69.2**
Excavation and transportation of the contaminated sediments and surface soils for on-base
disposal as appropriate and surface water monitoring as appropriate if contamination
remains at the site that threatens surface water quality.
*
**
***
This remedial alternative applies to Sites 7/11.
Soils do not overlay a contaminated groundwater plume , Main Base Groundwater Plume, Strategic Air
Command Industrial Groundwater Plume, Site 7 Groundwater Plume, Northeast Groundwater Plume).
This remedial alternative applies to Sites 37/39/54.
RL/2-16-96/ES/1260005.AWS
2-3
-------
2. 7.5 Statutory Determinations
The selected remedies satisfy the statutory requirements of Section 121(b) of CERCLA, as
amended by SARA, in that the following mandates are attained:
• the selected remedies are protective of human health and the environment;
• the selected remedies comply with federal and state requirements that are legally
applicable or relevant and appropriate to the remedial actions;
• the selected remedies are cost-effective; and
• the selected remedies utilize permanent solutions and alternative treatment
technologies, or resource recovery technologies, to the maximum extent
practicable.
These remedies will result in hazardous substances remaining at some sites (i.e., Sites 56, 62,
and 69) above levels that threaten human health or the environment during the remedial action.
In addition, any of the remedial actions may result in contaminants remaining at the site above
levels that allow for unlimited use. Therefore, a review will be conducted no less often than
every five years after commencement of the selected remedial actions to ensure that the
remedies continue to provide adequate protection of human health and the environment, and
protect groundwater quality for its beneficial uses.
2.2 Decision Summary for So/I OU Sites Selected for Remedial Action
2.2.1 Site Names, Location, and Description
The Soil OU sites selected for remedial action at the formerly active Mather AFB are
presented in Figure 2-1 and include: Site 7/11 - "7100 Area" Disposal Site/Existing Fire
Protection Training Area, Site 13 - Drainage Ditch Number 1, Site 15 - Drainage Ditch
Number 3, Site 20 - Sewage Treatment Plant, Site 37/39/54 - Building 3389/Hazardous Waste
Central Storage Facility, Site 56 - OWS 2989, Site 57 - OWS 7019, Site 59 - OWS 4251, Site
60 - OWS 6900, Site 62 - Jet Engine Test Cell (Facility 7099) and OWS 7110, Site 65 - OWS
6910, and Site 69 - Open Burn/Open Detonation Area. More detailed site maps are presented
hi the Groundwater OU and Soil OU FFS Report [IT 1995a].
2.2.2 Site History and Enforcement Activities
Previous investigations have been conducted at the Soil OU sites selected for remedial action
as part of the USAF IRP and are summarized hi Table 2-2.
RL/2-16-96/ES/1260005.AWS
2-4
-------
Sunrise Btvd.
RU10-95/ES/I260005.AWS
2-5
-------
2.2.3 Highlights of Community Participation
The public participation requirement of CERCLA Sections 113(k)(2)(B)(I-v) and 117 were met
through a public comment period (held May 8 through June 7, 1995) and public meeting (held
May 18, 1995) to address the Proposed Plan and content of supporting RI/FS documents.
2.2.4 Scope and Role of Response Action
Environmental studies were initiated by the USAF in 1982 to investigate soil contamination
resulting from past operations at the base. The USEPA placed Mather AFB on the NPL (or
"Superfund" list) in 1989. In order to organize cleanup efforts, the base was divided into five
OUs. This has allowed sites with similar sources of contamination and site conditions to be
grouped together. The following section of this ROD discusses the cleanup options for one of
the OUs, the Soil OU. Section 5.0 of this ROD presents cleanup options for the Groundwater
OU. Previous RODs presented cleanup options for the AC&W OU [IT 1993e] (where
contaminated groundwater is now being extracted and treated by air stripping) and the Landfill
OU [IT 1994b]. Any sites not addressed in the ROD will be addressed in an upcoming Final
Basewide OU ROD.
2.2.5 Summary of Site Characteristics
Contamination exists at the Soil OU sites as a result of past USAF operations conducted
between 1918 and 1993. The Soil OU is comprised of contaminated soils associated with
waste disposal pits, OWSs, gas stations, USTs, fire training areas, and other miscellaneous
sites. Any impact to the groundwater underlying these sites is addressed in the Groundwater
OU section of this ROD (Section 5.0).
Previous RIs have been conducted at Soil OU sites as part of the USAF IRP. A brief
description of each of the Soil OU sites recommended for remedial action, including
summaries of hazardous material releases and the nature and extent of contamination is
provided in the following sections (contamination area and volume estimates for the sediments,
surface soils, and subsurface soils are presented in Tables 2-3 through 2-5).
RL/2-16-96/ES/1260005.AWS
2-6
-------
Table 2-2. Previous Investigations at the Soil Operable Unit Sites Selected
for Remedial Action
Site Number
7/11
13
15
20
37/39/54
56
57
59
60
62
65
69
Applicable Investigation
1, 2, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15
1,3,5,7,9, 10, 11, 13, 14, 15
1,2,4,5,7, 9, 10, 11, 13, 14, 15
1, 3, 5, 7, 9, 10, 14, 15
7, 11, 12, 13, 14, 15
5,7, 11, 14, 15
7, 11, 14, 15
7, 11, 14, 15
11, 14, 15
11, 13, 14, 15
7, 11, 14, 15
7, 11, 13, 14, 15
1. Installation Restoration Program (IRP) Records Search for Mather Air Force Base, Phase I [CH2M-Hill,
Inc. 1982];
2. IRP Phase II, Stage 1 Investigation [Weston 1986];
3. IRP Phase II, Stage 2 Investigation [AeroVironment 1987];
4. IRP Phase II, Stage 3 Investigation [AeroVironment 1988];
5. Well Redevelopment and Sampling Plan [IT 1988a];
6. Solid Waste Assessment Test Report [IT 1993b];
7. Quarterly Routine Groundwater Sampling [IT 1995c] and [EA 1990a-c];
8. Landfill Gas Testing Report [IT 1988b];
9. Site Inspection Report [IT 1990a];
10. Group 2 Sites Remedial Investigation Report [IT 1992a];
11. Group 3 Sites Technical Memorandum [IT 1993a];
12. Underground Storage Tank Closure Reports [IT 1990b and IT 1993c-d];
13. Soil Operable Unit (OU) and Groundwater OU Additional Field Investigation Report [IT 1994a];
14. Groundwater OU and Soil OU FFS Report [IT 1995a]; and
15. Mather Baseline Risk Assessment Report [IT 1995d].
RL/2-16-96/ES/1260005.AWS
2-7
-------
Table 2-3. Estimated Areas and Volumes - Sediments
Site Number
13
15
69
Contaminant of Concern
4,7
2,4,5,6,7
1
Area (square feet)
2.4 x 10"
5.8 x 104
l.lx 103
Volume" (cubic feet)
4.8 x 104
1.2 xlO5
2.2 x 103
a = two foot depth assumed for sediment contamination
Contaminant of Concern = 1-Dioxins and Furans, 2-Polycyclic aromatic hydrocarbons, 4-Metals, 5-Total petroleum hydrocarbons,
6-Polychlorinated biphenyls, and 7-Pesticides.
Table 2-4. Estimated Areas and Volumes - Surface Soils
Site Number
11
13
20
39
56
62
65
69
Contaminant of Concern
1
3,4,5
4
5
2,3,4,5
2,4,5
3,4,5
1
Area (square feet)
1.9xl05
l.lxlO3
5.4 x 104
3.0 x 103
1.5 x 103
5.4 x 103
2.2 x 103
1.2x 10s
Volume" (cubic feet)
3.8x 105
2.2 x 103
1.1 x 105
6.0 x 103
2.9 x 103
1.1 x 104
4.3 x 103
2.3 x 105
a = two foot depth assumed for calculating volumes
Contaminant of Concern = 1-Dioxins and Furans, 2-Polycyclic aromatic hydrocarbons, 3-Oil and grease, 4-Metals, and 5-TotaI petroleum
hydrocarbons.
Table 2-5. Estimated Areas and Volumes - Subsurface Soils
Site Number
r
20
37
39
Contaminant of Concern
TPH-D
TPH-G
Thallium
TPH-D
Benzene
Oil and Grease
TPH-D
TPH-G
Benzene
TPH-D
TPH-G
Area (square feet)
1.9 x 105
2.0 x 105
1.3 x 103
1.2x 103
(a)
3.1 x 102
3.1 x 102
5.1 xlO3
6.0 x 10"
(b)
4.1 xlO4
Volume (cubic feet)
2.9 x 106
3.0 x 106
6.0 x 104
1.5x 104
(a)
3.5 x 103
3.5 x 103
1.3 x 10s
1.5 xlO6
(b)
1.7 xlO6
RL/2-16-96/ES/1260005.AWS
2-8
-------
Site Number
54
56
57
59
60
62
65
Contaminant of Concern
Benzene
TPH-G
Oil and Grease
Lead
TPH-D
TPH-G
Trichloroethene
TPH-D
TPH-G
TPH-G
TPH-D
TPH-D
TPH-G
Area (square feet)
(a)
8.0 x 102
©
©
8.9 x 102
8.8 x 102
4.9 x 104
6.7 x 102
1.6x 103
6.6 x 102
2.3 x 102
2.0 x 102
1.6x 103
Volume (cubic feet)
(a)
2.0 x 104
©
©
1.3 x 104
1.3x10"
2.6 x 106
1.4x 104
3.2 x 104
9.9 x 103
2.5 x 103
3.1xl03
2.4 x 104
* Site 11 contains some contamination adjacent to Site 7 that will be remediated under the Site 7 alternative. The area and volume estimates
will likely increase during remedial design.
(a) = included with the area, volume, and mass of Site 39
(b) = diesel detections are sporadic and coincide with higher concentration gasoline detections
0 = three detections above background, detections coincide with gasoline and diesel detections
TPH-D = Total petroleum hydrocarbons as diesel
TPH-G = Total petroleum hydrocarbons as gasoline
2.2.5. 1 Site 7/11 - "7100 Area" Disposal Site/Existing Fire Protection Training
Area
For purposes of remediation, Sites 7 and 11 were grouped together based on proximity and
common contaminants.
Site 7 is located in the southwest corner of the base and has been used as a disposal area since
1953. The site was originally a gravel borrow pit excavated to a depth of approximately
40 feet. From 1953 until approximately 1966, this site was a major disposal area for
petroleum, oil, and lubricant (POL) wastes. Other waste reportedly disposed of includes
empty drums, sludge from plating-shop dip tanks, absorbent sand used for cleaning oil and
solvent spills, paint chips, waste paint and thinners, and at least one load of transformer oil
that may have contained polychlorinated biphenyls (PCBs).
Site 11 is located south of the Sewage Treatment Plant and adjacent to Site 7. Fire training
exercises were conducted there from 1958 until 1993. Two jet propellant fuel (JP-4)
aboveground storage tanks (ASTs) were installed in 1974; these have since been replaced.
The facility was upgraded to include a lined burn pit in the mid-1980's.
RL/2-16-96/ES/1260005. A WS
2-9
-------
Contamination at Site 7 has been identified in the shallow and deep subsurface soils. The
COCs identified at the site are diesel, gasoline, lead, and thallium. Contamination at Site 11
has been identified hi the surface soils. The COCs identified at Site 11 are dioxins and furans.
These are not selected for remediation, but will be excavated as part of the Site 7 cleanup, and
incorporated into the foundation for the cap at Site 7. This decision is based on dioxin
detections below the cleanup standards set in response to regulatory comments on the risk
assessment. Site 7 is the apparent historic source for ground water contamination (see Section
5.2.5.2); although there have been no significant detections of chlorinated solvents in the Site
7/11 soils, soil gas will be monitored during remedial design per Section 2.2.9.1. The bases
for cleanup are compliance with ARARs for waste disposal sites, mitigating a likely source of
groundwater contamination, and protection of groundwater for its beneficial uses.
2.2.5.2 Site 13 - Drainage Ditch Number 1
Site 13 is located just north of the northeast end of runways, and is part of the surface drainage
system for the base. Oil/water separator 3990 was installed at the site in 1968, and received
runoff from two aircraft wash pads via area drains and piping. Prior to installation of OWS
3990, the waste may have been poured directly into the drainage ditch and/or a nearby shallow
excavation.
Contamination at the site has been identified in the surface water, sediments, and surface soils.
The COCs identified at the site are metals, pesticides, polycyclic aromatic hydrocarbons
(PAHs), diesel, and oil and grease. The basis for cleanup is protection of ecological receptors
and groundwater quality, and surface water quality.
2.2.5.3 Site 15 - Drainage Ditch No. 3
Site 15 covers the portion of the West Ditch that trends north-south along the western
boundary of the base, 1,500 feet east of Happy Lane Boulevard and directly west of the former
Strategic Air Command (SAC) portion of the base. The ditch is unlined and received surface
runoff from the Main Base area, including the Air Training Command (ATC) and former SAC
shops. Until about 1971, floor drains in the shops were connected to the storm sewer system
which emptied into the West Ditch.
Oil/water separator 7039 is located at the southern end of the West Ditch and was installed hi
1967. Waste oils and solvents were reportedly dumped directly into the separator system and
occasionally overflowed into the West Ditch. Prior to construction of OWS 7039, waste oil
was reportedly dumped into a below ground metal container or tank near the present location
of the OWS.
RL/2-16-96/ES/1260005.AWS
2-10
-------
Contamination at the site has been identified hi the surface waters and sediments. The COCs
identified at the site are metals, pesticides, PAHs, PCBs, gasoline, diesel, and oil and grease.
The basis for cleanup is protection of ecological receptors and surface water quality.
2.2.5.4 Site 20 - Sewage Treatment Plant
Site 20 is located in the southwest portion of the base. This site contained a 150-gallon diesel
UST that was excavated and removed hi 1985. An estimated 700 gallons of diesel fuel leaked
from the tank. Some sludge from the former waste water treatment at Site 20 remains on the
site adjacent to the sludge drying beds, not associated with the diesel spill location. This
sludge was planned for an expedited removal action hi 1995, according to a Removal Action
Memorandum dated September 1994. Recent sampling determined that the sludge contains
hazardous waste and non-designated waste, and current plans are to dispose of any non-
hazardous and non-designated sludge into Site 4 during landfill closure. This removal was
delayed until 1996 because of budgetary constraints. Additional 'new' sludge was removed
from digester tanks at Site 20 during demolition of these tanks in 1995, This 'new' sludge has
remained isolated on site while it has been characterized for disposal; portions have been
found to contain hazardous concentrations of mercury (as is reported hi the Draft Additional
Site Characterization Remedial Investigation Report, IT Corp., 1996). This sludge will be
disposed of as hazardous waste, or stabilized as planned for lead-bearing sludge hi the 1994
Removal Action Memorandum (IT, 1994c) to render it non-hazardous and non-designated for
on-base disposal. In response to the detection of mercury in the 'new' sludge, a cleanup level
for mercury at Site 20 has been added to this ROD, and will apply to all sludge and shallow
soils.
The COCs identified at the sludge site are metals, while the only COC identified at the UST
site is diesel. The bases for cleanup are protection of ecological receptors and groundwater
quality.
2.2.5.5 Site 37/39/54 - Building 3389/Hazardous Waste Centra/ Storage
For purposes of remediation, Sites 37, 39, and 54 were grouped together based on proximity
and common contaminants.
Site 37 is located in the northwest portion of the base and is associated with five steel USTs at
Building 3389. Four of the USTs had a capacity of 12,000 gallons and stored diesel fuel, lube
RL/2-16-96/ES/1260005.AWS
2-11
-------
oil, and waste oil. The fifth UST had a capacity of 550 gallons and stored kerosene and
solvents.
Site 39 operated from 1988 to 1993 as a hazardous waste storage facility permitted under the
RCRA. Site 39 is a fenced compound located in the Main Base area consisting of a
gravel-covered storage yard that contains several concrete pads and buildings. A variety of
hazardous wastes were stored at this site. The site contained eight 25,000 gallon USTs used to
store waste fuels and aviation gasoline, as well as one waste oil and one waste jet fuel AST.
The USTs and ASTs were removed in 1993.
Site 54 is a RCRA facility and was a 90-day holding yard comprised of a large, fenced,
asphalt-paved yard. The asphalt-paved yard is extensively cracked, and sealant applied to the
cracks has eroded in many places. Bowsers and drums of waste hydraulic fluids, PD-680 (a
commercial variety of Stoddard solvent), and Citrikleen (a petroleum-based solvent that
contains no chlorinated or aromatic solvents) were stored at the site at least since 1982.
Contamination at the combined sites has been identified in the surface soils, shallow
subsurface soils, and deep subsurface soils. The COCs identified at the site are benzene,
toluene, ethylbenzene, and xylenes (BTEX), diesel, gasoline, lead, and oil and grease. In
addition, chlorinated solvents were detected at the combined Site 37/39/54 during the
Additional Site Characterization (IT Corp., 1996). These contaminants will be evaluated in
the feasibility study for the Final Operable Unit, and incorporated as appropriate in the
remedial action for these sites as described in Section 2.2.9.5. The basis for cleanup is
protection of groundwater quality.
2.2.5.6 Site 56 - Oil/Water Separator 2989
Site 56 consists of OWS 2989 located in the eastern portion of the Main Base and two former
OWS facilities. Oil/water separator 2989 was used to receive wastewater generated at the Old
Motor Pool washrack, which were treated and discharged to the sanitary sewer system. The
following materials were reportedly contained in the wastewater: fuels, oil and grease,
antifreeze, and possibly cleaning fluids.
Contamination has been identified in the surface soils and shallow subsurface soils. The COCs
identified at the site are diesel, gasoline, metals, PAHs, and oil and grease. A current cancer
RL/2-I6-96/ES/1260005.AWS
2-12
-------
risk to humans (3.3 x 10"4) and a potential future cancer risk to humans (8.0 x 10"4 ) have been
identified. The basis for cleanup is protection of human health and groundwater quality.
2.2.5.7 Site 57 - Oil/Water Separator 7019
Site 57 consists of OWS 7019 and is located in the central portion of the SAC area. This
OWS was used to separate oils, fuels, hydraulic fluids, and PD-680 from the Aerospace
Ground Equipment (AGE) Shop washwaters, and discharge the waters to the sanitary sewer
system.
Contamination at the site has been identified in the shallow subsurface soils. The only COC
identified at the site is trichloroethene (TCE). The basis for cleanup is protection of
groundwater quality.
2.2.5.8 Site 59 - O/7/Water Separator 4251
Site 59 consists of OWS 4251 and is located in the southern portion of the Main Base at the
ATC washrack, approximately ten feet south of Building 4252. Oil/water separator 4251 was
constructed in 1969 and received waste water generated from the ATC washrack. The
wastewater reportedly contained fuels, oil and grease, hydraulic fluid, and antifreeze.
Contamination at the site has been identified in the shallow subsurface soils. The COCs
identified at the site are diesel and gasoline. The basis for cleanup is protection of
groundwater quality.
2.2.5.9 Site 60 - Oil/Water Separator 6900
Site 60 consists of OWS 6900 which is located in the SAC area and supported Building 7005.
Building 7005 was an aircraft maintenance hanger used for aircraft fuel-system maintenance.
A large floor (trench) drain within the hanger was used to collect fuel that emptied from an
aircraft, which then emptied into underground vaults immediately outside the building. A
conduit in the bottom of the vault led to the OWS. It is reported that TCE, perchloroethene
(tetrachloroethene) (PCE), methyl ethyl ketone, and other solvents were used in Building
7005.
Contamination at the site has been identified in the shallow subsurface soils. The COCs at the
site are gasoline and xylenes. The basis for cleanup is protection of groundwater quality.
RL/2-16-96/ES/1260005.AWS
2-13
-------
2.2.5.10 Site 62 - OWS 7110 and Jet Engine Test Cell
Site 62 is located in the southwest portion of the base and consists of an abandoned Jet Engine
Testing Cell (JETC) and adjoining OWS 7110, built in 1961. The JETC consisted of asphalt
and concrete pads, Building 7098, a groundwater production well, and a water storage and
treatment system. The site was used to test the operation of jet engines. Oils, fuels, and
solvents may have been used at the site. Runoff from the JETC drained onto the surrounding
soils. The OWS drained into a ditch running west near Building 7099.
Contamination at the site has been identified in the surface soils and shallow subsurface soils.
The COCs identified at the site are diesel, metals, and PAHs. A future cancer risk to humans
(1.5 x 10"4) has been identified. The basis for cleanup is protection of human health,
ecological receptors, and groundwater quality.
2.2.5.11 Site 65 Oil/Water Separator 6910
Site 65 consists of OWS 6910 and is located in the north section of the SAC area at the old
AGE Shop, approximately 35 feet northeast of Building 7009. Oil/water separator 6910 was
constructed in the mid-1960s and received wastewater containing fuels, oils, hydraulic fluids,
and antifreeze generated from Building 7009. Effluent lines from OWS 6910 were reportedly
connected to the sanitary sewer system in 1972.
Contamination at the site has been identified in the surface soils and shallow subsurface soils.
The COCs identified at the site are chromium, diesel, gasoline, lead, and oil and grease. The
basis for cleanup is protection of groundwater quality.
2.2.5. 72 Site 69 - Open Burn Detonation Area
Site 69 is an excavated area in the southeastern portion of the base, reportedly used for
destruction of unwanted small ordnance, classified aircraft parts, and other materials. At the
south end is a burn pit approximately four feet deep and ten feet in diameter. The excavation
is unpaved and unlined, and drains southwest to join an unnamed ephemeral tributary. At the
northern end of the site are two small bunkers, a personnel bunker and a popping furnace,
which were in use since the 1950s until 1993.
RL/2-16-96/ES/1260005. A WS
2-14
-------
Contamination at the site has been identified in the surface water, sediments, and surface soils.
The COCs identified at the site are metals and dioxins and furans. A potential future cancer
risk to humans has been identified (1.1 x 10"*). The basis for cleanup is protection of human
health, ecological receptors, and surface water quality.
2.2.6 Summary of Site Risks
Remedial investigation activities at Mather AFB included fate and transport modeling and a
baseline risk assessment (e.g., Mather Baseline Risk Assessment [MBRA]) [IT 1995d]. The
data collected and utilized in the RIs and FFS were of USEPA quality Level ffl, IV, or V, or
equivalent [USEPA 1987]. Formal data validation of the RI- and FFS-generated data was
performed to ensure that data were of the quality commensurate with their intended use.
Although a majority of the Soil OU sites are currently controlled by the USAF, Mather AFB
was decommissioned on September 30, 1993. Future land use is either residential or
industrial, depending on the individual site. The following sections describe the criteria used
to screen contaminants of potential concern (COPCs).
2.2.6.1 Human Health Risks
Analytes detected in the course of the RI activities (e.g., COPCs) at Mather AFB were
subjected to a multi-step screening process to determine COCs. This screening process is
presented in the following sections. The following steps were employed in the COC
determination process for the Soil OU sites.
• initial screening methods prescribed by USEPA guidance;
• comparison to background;
• comparison to ARARs;
• comparison to analytical method quantitation limit;
• evaluation of operational history (i.e., process knowledge); and
• evaluation of estimated risk to human and ecological receptors.
RL/2-16-96/ES/1260005.AWS
2-15
-------
2.2.6.1.1 Initial Screening
Remedial investigation data collected at the Soil OU sites were used to identify the initial
COPCs. The list of initial COPCs was reduced using the following methods as prescribed by
USEPA guidance [USEPA 1989a]:
• Quality Control Blank Contamination - As part of the data validation process, a
chemical was not considered further if the maximum sample concentration did
not exceed ten times the highest blank for all common laboratory contaminants
(2-butanone, acetone, methylene chloride, phthalates, and toluene) or five times
the highest blank for other chemicals. This screening action reduced the
inclusion of chemicals that are most likely sampling or analytical artifacts.
• Frequency of Detection - Chemicals were eliminated if they were detected in
five percent or less of the samples for a site. Infrequently detected chemicals
may be artifacts of sampling, analytical, or other problems.
• Essential Nutrients - Calcium, carbonates, iron, magnesium, phosphorus,
potassium, sodium, and sulfates are essential nutrients. These constituents are
generally toxic only at very high doses and were eliminated because they were
detected at levels below toxic concentrations.
All analytes which passed this initial screening, and associated chemical results were compiled
on a site-specific basis to calculate the 95 percent upper confidence limit (UCL) on the mean
concentration for each chemical. The 95 percent UCL for each COPC was used during
subsequent steps in the COC determination process. The results of the initial screening and
compilation are presented in the Group 2 Sites RI [IT 1992a] and the MBRA [IT 1995d].
2.2.6.1.2 Comparison to Background
A comparison of COPC concentrations to Mather AFB background concentrations was
performed to determine if detections in environmental samples were due to naturally occurring
constituents. This comparison utilized data from the "Background Inorganic Soils for Mather
Air Force Base" report [IT 1993f].
2.2.6.1.2.1 Surf ace Water
For inorganics (only), deionized (D.I.) water waste extraction tests (WET) were performed on
background surface soil/sediment samples. The associated results indicated the concentrations
of metals which may be present in surface waters as a result of leaching from background
RL/2-16-96/ES/1260005.AWS
2-16
-------
surface soils/sediments. Accordingly, the D.I. WET results are indicative of naturally
occurring (background) concentrations of metals in surface waters in the area of Mather AFB.
Inorganic COPC concentrations in surface water were compared to the background soil
D.I. WET results; COPCs for which maximum concentrations were less than associated
D.I. WET results were eliminated from further consideration. Inorganics for which D.I. WET
data were not available, and for all organics, background concentrations in surface water were
assumed to be zero.
2.2.6.1.2.2 Soils and Sediments
For inorganics and oil and grease, the associated 95 percent UCLs for each COPC were
compared to documented background levels [IT 1993g],
The COPCs for which the 95 percent UCL were within background concentrations/ranges,
were eliminated from further consideration. For inorganics for which background data were
not available, and for all organics with the exception of oil and grease, background
concentrations were assumed to be zero.
The results of this comparison are presented in the MBRA [IT 1995d] and are reiterated hi the
FFS Report [IT 1995a].
2.2.6.1.3 Comparison to Analytical Method Quantitation Limit
For solid media, the calculated 95 percent UCLs were compared to the quantitation limit for
each corresponding analytical method. In some cases, the 95 percent UCL was less than the
quantitation limit as follows.
The initial data compilation was performed in accordance with USEPA risk assessment
guidance [USEPA 1989a]. Such guidance mandates the inclusion of data qualified as not
detected (i.e., ND) to be included in the database at a value of one-half the quantitation limit.
Although such an approach is compatible with the conservative nature of risk assessment,
associated results are frequently of limited value in an engineering context. Accordingly, if
the 95 percent UCL was less than the quantitation limit the associated COPC was considered
"not detected."
RL/2-16-96/ES/1260005.AWS
2-17
-------
2.2.6.1.4 Comparison to Applicable or Relevant and Appropriate
Requirements/To-Be-Considered
Chemical-specific ARARs were identified for surface water and soils and are further described
in Section 6.0. There were no chemical-specific ARARs identified for air; however, the
action-specific ARARs will control the release of pollutants to the air from the soils during
remediation activities. Federal and state water regulation primary maximum contaminant
levels (MCLs) were used for comparison to surface water and groundwater.
2.2.6.1.4.1 Surface Water
Contaminant of potential concern concentrations in surface waters were compared to
appropriate to-be-considered materials (TBC), in most cases USEPA Ambient Water Quality
Criteria (AWQC). The COCs for which the 95 percent UCL was less than the corresponding
TBC were eliminated from further consideration.
2.2.6.1.4.2 Soils
Contaminant of potential concern concentrations in sediments and soils were compared to total
designated levels (TDLs) calculated using the Designated Level Methodology (DLM)
[CVRWQCB 1989].
The DLM was used to evaluate or estimate potential impact to the groundwater from COPCs
in the surface and subsurface soils. The DLM was also used to screen COPCs in sediments to
evaluate potential impacts to surface water. The application of this methodology consisted of
the following steps:
• Determine the desired water quality goal (WQG) for each constituent -
Promulgated regulations and standards were used where available.
Contaminants in the surface soils and subsurface soils have a potential to impact
groundwater (i.e., source of drinking water); therefore, the MCL was used as
the WQG. Contaminants in the sediments could possibly impact surface waters;
therefore, AWQC were used as the WQG. In the absence of promulgated
regulations, contaminant goals, health advisories, or risk-based values were
used as WQGs.
• Determine the Environmental Attenuation Factor for each constituent - This
factor is used to transform WQGs into site-specific designated levels
(concentrations of constituents in the wastes that have the potential to degrade
water quality by migrating from the reference location).
RL/2-16-96/ES/1260005. A WS
2-18
-------
Determine a Leachability Factor - The teachability factor is the ratio of total to
soluble concentrations of the chemical constituent. Where available, actual
deionized solubilities determined using the California Waste Extraction Text
protocol were used to assess the threat to water quality. Where measured
solubilities were unavailable, a theoretical leachibility factor was used. This
factor was used to determine the fraction of the total constituent concentration
available for leaching from the waste. The remaining portion of the constituent
is immobile or unavailable for leaching due to encapsulation in the waste matrix
or chemical bonding. A leachability factor of 100 was used for inorganic
constituents and 10 for organic constituents as prescribed in the DLM guidance
[CVRWQCB 1989], subject to agency review and professional judgement
during document review.
Determine a Total Designated Level - The TDL represents the concentration of
a constituent in a solid waste which, if exceeded, may threaten the water
TDL = WQG x EAF x LF
quality. The TDL is calculated by the following equation:
where: TDL = total designated level
WQG = water quality goal
EAF = environmental attenuation factor
LF = leachability factor
The COPCs for which the 95 percent UCL was less than the associated TDL were eliminated
from further consideration, subject to reinstatement as COPCs if warranted by comment
resolution or professional judgement during document review.
2.2.6.1.5 Process Knowledge Evaluation
Operational and disposal histories for the Soil OU sites were reviewed to evaluate the
likelihood that past operations or disposal practices may have impacted the proximate
environment. Results of the process knowledge evaluation were developed in accordance with
the following definitions:
Yes: documented, reported, or observed evidence (e.g., floating-product in an
excavation) of a release for that COPC;
Possible: evidence or documentation that the COPC was used or stored at the site;
No: no evidence that the COPC was stored, used, and/or released at the site.
9 1Q
RL/2-16-96/ES/1260005.AWS ^17
-------
Process knowledge was not used as sole justification, but was used in conjunction with the
other screening criteria, to aid in the elimination of constituents from the list of COPCs.
2.2.6.1.6 Risk Assessment Results
Estimates of potential risks/hazards to human and ecological receptors were obtained from the
MBRA [IT 1995d]. Recent revisions include the use of surrogate toxicity values, an updated
dermal exposure model, revised dermal absorption values, and an aggregate mining scenario
[IT 1995b]. Additional ecological risk assessment activities were conducted in Spring 1995.
These activities included further evaluation of the potential toxicity of surface water, sediment,
and surface soil contaminants at three local habitat types and respective reference sites through
toxicity testing and residue analysis. The house mouse exposure pathway was also
re-evaluated utilizing an assumption of an omnivorous mouse. The initial list of COPCs
(presented in the FFS Report [IT 1995a]) which were identified on the basis of potential
ecological risk/hazard have not changed appreciably due to these additional activities.
From an ecological perspective, COPCs for which concentrations exceeded background
screening values or for which associated estimates of potential ecological hazard index
exceeded 1.0 were also identified as COCs. An ecological risk exists at Sites 13, 15, 20, 62,
and 69. Therefore, the selected remedies at these sites will be instituted for the protection of
ecological receptors and/or surface water quality.
From a human health perspective, COPCs for which the estimated incremental lifetime cancer
risk exceeded 1 x 10"6, or the hazard quotient exceeded 1.0, on an individual pathway basis,
were identified as COCs.
Based on the human health risk assessment, all cancer risks were within or below the
acceptable range of 1 x 10^ to 1 x 10~6 in their current state, except for Sites 56, 62, and 69
which have a current and future cancer risk greater than 1 x 10"4. Therefore, the selected
remedies at Sites 56, 62, and 69 will be instituted to reduce human health risks and/or for
protection of groundwater quality.
Actual or threatened releases of hazardous substances, if not addressed by implementing the
response actions selected in the ROD, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
RL/2-16-96/ES/1260005.AWS
2-20
-------
2.2.7 Description of Alternatives
A total of 36 remedial alternatives (including the no action alternative) for the twelve Soil OU
sites which warrant remedial action were developed for detailed analysis in the FFS Report [IT
1995a]. Soil is the affected medium at these sites. Any contamination of the groundwater
underlying the soil sites is addressed in the Groundwater OU section of this ROD (Section
5.0).
In developing the alternatives, it was assumed that the sediments (maximum two foot deep),
surface soils (zero to two feet below land surface [bis]), and shallow soils (2 to 30 feet bis) are
capable of being excavated without specialized equipment. Deep soils (30 feet bis to the water
table) are not considered feasible or appropriate to excavate. The no action alternative, as
required by CERCLA, has been included for each site to provide a baseline.
2.2.7.1 Site 7/11 Remedial Alternative
Table 2-6 presents three remedial alternatives that have been developed for possible application
at Site 7/11.
Table 2-6. Site 7/11 Remedial Alternatives
ALTERNATIVE
7.1
7.2
7.3
DESCRIPTION
No Action
Excavation (shallow soils) with ex situ bioremediation and on-base disposal (or off-
base disposal if the excavated material is classified as hazardous waste or would be
classified as designated waste at the on-base disposal site(s)); in situ bioremediation
and possibly soil vapor extraction (SVE) (deep soils); capping (as appropriate); and
groundwater monitoring (if contamination that threatens groundwater quality remains
at the site).
Filling hi the depression at site 7 to grade; in situ bioremediation and possibly SVE
(shallow and deep soils at sites 7 and 11); capping (as appropriate); and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site).
2.2.7.2 Site 13 Remedial Alternatives
Table 2-7 presents three remedial alternatives that have been developed for possible application
at Site 13.
RL/2-16-96/ES/I260005.AWS
2-21
-------
Table 2-7. Site 13 Remedial Alternatives
ALTERNATIVE
13.1
13.2
13.3
DESCRIPTION
No Action
Excavation (sediments and surface soils) with off-base disposal and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site)
Excavation (sediments and surface soils) with ex situ bioremediation and on-base disposal
(or off-base disposal if the excavated material is classified as hazardous waste or would
be classified as designated waste at the on-base disposal site(s)); and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site)
2.2.7.3 Site 15 Remedial Alternatives
Table 2-8 presents three alternatives that have been developed for possible application at
Site 15.
Table 2-8. Site 15 Remedial Alternatives
ALTERNATIVE
15.1
15.2
15.3
DESCRIPTION
No Action
Excavation (sediments) with off-base disposal and surface water monitoring (if
contamination that threatens surface water quality remains at the site)
Excavation (sediments) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); and surface water monitoring (if
contamination that threatens surface water quality remains at the site)
2.2.7.4 Site 20 Remedial Alternatives
Table 2-9 presents three alternatives that have been developed for possible application at
Site 20.
Table 2-9. Site 20 Remedial Alternatives
ALTERNATIVE
20.1
- 20.2
20.3
DESCRIPTION
No Action
Excavation (shallow soils) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); and groundwater monitoring (if
contamination that threatens groundwater quality remains at the site)
In situ bioremediation (shallow soils) and groundwater monitoring (if contamination
that threatens groundwater quality remains at the site)
RL/2-16-96/ES/1260005.AWS
2-22
-------
2.2.7.5 Site 37/39/54 Remedial Alternative
Table 2-10 presents three remedial alternatives that have been developed for possible
application at Site 37/39/54.
Table 2-10. Site 37/39/54 Remedial Alternatives
ALTERNATIVE
DESCRIPTION
37.1
No Action
37.2
Excavation (surface soils) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); in situ bioremediation and possibly
soil vapor extraction (SVE) (shallow and deep soils); and groundwater monitoring (if
contamination that threatens groundwater quality remains at the site)
37.3
Excavation (surface and shallow soils) with ex situ bioremediation and on-base disposal
(or off-base disposal if the excavated material is classified as hazardous waste or would
be classified as designated waste at the on-base disposal site(s)); in situ bioremediation
and possibly SVE, (deep soils); and groundwater monitoring (if contamination that
threatens groundwater quality remains at the site)
2.2.7.6 Site 56 Remedial Alternatives
Table 2-11 presents three remedial alternatives that have been developed for possible
application at Site 56.
Table 2-11. Site 56 Remedial Alternatives
ALTERNATIVE
56.1
56.2
56.3
DESCRIPTION
No Action
Excavation (surface soils) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); in situ bioremediation (shallow
soils); and groundwater monitoring (if contamination that threatens groundwater quality
remains at the site)
Excavation (surface and shallow soils) with ex situ bioremediation and on-base disposal
(or off-base disposal if the excavated material is classified as hazardous waste or would
be classified as designated waste at the on-base disposal site(s)); and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site)
RL/2-16-96/ES/1260005.AWS
2-23
-------
2.2.7.7 Site 57 Remedial Alternatives
Table 2-12 presents three remedial alternatives that have been developed for possible
application at Site 57.
Table 2-12. Site 57 Remedial Alternatives
ALTERNATIVE
57.1
57.2
57.3
DESCRIPTION
No Action
In situ bioremediation (shallow and deep soils) and groundwater monitoring (if
contamination that threatens groundwater quality remains at the site)
In situ soil vapor extraction (shallow and deep soils) and groundwater monitoring
contamination that threatens groundwater quality remains at the site)
(if
2.2.7.8 Site 59 Remedial Alternatives
Table 2-13 presents three remedial alternatives that have been developed for possible
application at Site 59.
Table 2-13. Site 59 Remedial Alternatives
ALTERNATIVE
59.1
59.2
59.3
DESCRIPTION
No Action
Excavation (shallow soils) with ex situ bioremediation and on-base disposal (or off-
base disposal if the excavated material is classified as hazardous waste or would be
classified as designated waste at the on-base disposal site(s)); and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site)
In situ bioremediation (shallow soils) and groundwater monitoring (if contamination
that threatens groundwater quality remains at the site)
RL/2-16-96/ES/1260005.AWS
2-24
-------
2.2.7.9 Site 60 Remedial Alternatives
Table 2-14 presents four remedial alternatives that have been developed for possible
application at Site 60.
Table 2-14. Site 60 Remedial Alternatives
ALTERNATIVE
60.1
60.2
60.3
60.4
DESCRIPTION
No Action
Excavation (shallow soils) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); and groundwater monitoring (if
contamination that threatens groundwater quality remains at the site)
In situ soil vapor extraction (shallow soils) and groundwater monitoring (if contamination
that threatens groundwater quality remains at the site)
In situ bioremediation (shallow soils) and groundwater monitoring (if contamination that
threatens groundwater quality remains at the site)
2.2.7.10 Site 62 Remedial Alternatives
Table 2-15 presents three remedial alternatives that have been developed for possible
application at Site 62.
Table 2-15. Site 62 Remedial Alternatives
ALTERNATIVE
62.1
62.2
62.3
DESCRIPTION
No Action
Excavation (surface soils) with ex situ bioremediation and on-base disposal (or off-base
disposal if the excavated material is classified as hazardous waste or would be classified
as designated waste at the on-base disposal site(s)); in situ bioremediation (shallow soils);
and groundwater monitoring (if contamination that threatens groundwater quality remains
at the site)
Excavation (surface and shallow soils) with ex situ bioremediation and on-base disposal
(or off-base disposal if the excavated material is classified as hazardous waste or would
be classified as designated waste at the on-base disposal site(s)); and groundwater
monitoring (if contamination that threatens groundwater quality remains at the site)
RL/2-16-96/ES/1260005.AWS
2-25
-------
2.2.7.11 Site 65 Remedial Alternatives
Table 2-16 presents three remedial alternatives that have been developed for possible
application at Site 65.
Table 2-16. Site 65 Remedial Alternatives
ALTERNATIVE
65.1
65.2
65.3
DESCRIPTION
No Action
Excavation (surface soils) with off-base disposal; in situ bioremediation (shallow soils);
and groundwater monitoring (if contamination that threatens groundwater quality remains
at the site)
Excavation (surface soils) with off-base disposal; excavation (shallow soils) with ex situ
bioremediation and on-base disposal (or off-base disposal if the excavated material is
classified as hazardous waste or would be classified as designated waste at the on-base
disposal site(s)); and groundwater monitoring (if contamination that threatens
groundwater quality remains at the site)
2.2.7.12 Site 69 Remedial Alternatives
Table 2-17 presents two remedial alternatives that have been developed for possible application
at Site 69.
Table 2-17. Site 69 Remedial Alternatives
ALTERNATIVE
69.1
69.2
DESCRIPTION
No Action
Excavation (sediments and surface soils) with on-base disposal (or off-base disposal if the
excavated material is classified as hazardous waste or would be classified as designated
waste at the on-site disposal area), and surface water monitoring as appropriate if
contamination remains on site that threatens surface water quality.
2.2.8 Summary of Comparison Analysis of Alternatives
The remedial alternatives developed in the FFS Report [IT 1995a] were analyzed hi detail
using the nine evaluation criteria required by the NCP (Section 300.430(e)(7)). These criteria
are classified as threshold, primary balancing, and modifying criteria. In order for a remedial
alternative to be selected, it must at a minimum, meet the threshold criteria.
RL/2-16-96/ES/1260005.AWS
2-26
-------
Threshold criteria are:
overall protection of human health and the environment; and
compliance with ARARs.
Primary balancing criteria are:
• long-term effectiveness and permanence;
• reduction of toxicity, mobility, or volume through treatment;
• short-term effectiveness;
• implementability; and
• cost.
Modifying criteria are:
• state/support agency acceptance; and
• community acceptance.
The relative ability of each alternative to meet each of the nine criteria were weighed to
identify the alternative providing the best tradeoffs for each site. The following sections
summarize the nine criteria. Table 2-18 presents the results of the comparative analysis.
2.2.8.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether or not a cleanup
option provides adequate protection. It also describes how risks, posed through each exposure
route, are eliminated, reduced, or controlled through treatment, engineering controls, or
institutional controls.
2.2.8.2 Compliance with ARARs
Compliance with ARARs addresses whether a cleanup option will meet all ARARs or federal
and state environmental statues and/or provide grounds for invoking a waiver. Details of the
ARARs analysis are described in Section 6.0 of this ROD.
RL/2-16-96/ES/1260005.AWS
2-27
-------
2.2.8.3 Long- Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a cleanup option to maintain
reliable protection of human health and the environment over time, once cleanup goals have been
met.
2.2.8.4 Reduction of Toxlcity, Mobility, or Volume
Reduction of toxicity, mobility, or volume refers to the anticipated ability of a cleanup option to
reduce health hazards, contaminant migration, or quantity of contaminants at the site through
treatment.
2.2.8.5 Short-Term Effectiveness
Short-term effectiveness refers to the period of time in which the remedy achieves protection, as
well as the remedy's potential to prevent adverse impacts on human health and the environment
that may result during the excavation, construction, or implementation period until the cleanup
goals are achieved.
2.2.8.6 Implementability
Implementability refers to the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to carry out a particular remedy. It also includes
coordination of federal, state, and local governments in cleanup of the site.
2.2.5.7 Cost
This criterion examines the estimated cost for each remedial alternative. For comparison, capital
and annual operation and maintenance costs were used to calculate a present worth cost for each
alternative. The present worth cost estimates assume zero equipment salvage value, zero percent
inflation, and a five percent discount factor so that each option could be equally compared in
1994 dollars. A detailed cost analysis was performed for each of the alternatives proposed in the
FFS Report [IT 1995a].
2.2.8.8 State/Support Agency Acceptance
This indicates whether, based on review of the RI Report [IT 1992a], FFS Report [IT 1995a],
and Proposed Plan [IT 1995b], the state concurs with the preferred cleanup options. The State of
California is represented by the California Environmental Protection Agency, DTSC as a support
agency under the Federal Facility Agreement for Mather AFB; DTSC coordinates review
comments from other state agencies, such as the Central Valley Regional Water Quality Control
Board (CVRWQCB) and the Integrated Waste Management Board.
RL/2-16-96/ES/1260005.AWS
2-28
-------
Table 2-18. Comparative Analysis of Soil Operable Unit Remedial Alternatives
Evaluation
Criteria
Site
Number
Alternative
Overall Protection of Human
Health and the Environment
Compliance with
ARARs
Long-Term Effectiveness and
Permanence
Reduction of Toxicity,
Mobility, and Volume
Short-Term Effectiveness
Implementability
Present Worth Cost
($ millions)
7/11
7.1
Yes
NA**
G
P
F
G
0.018
7.2
Yes
Yes
B
B
B
G
4.21
7.3'
Yes
Yes
B
B
G
B
3.69
13
13.1
Yes
NA**
G
P
G
B
0.15
13.2
Yes
Yes
B
G
B
G
0.88
13.3'
Yes
Yes
B
B
B
G
0.279
15
15.1
Yes
NA**
F
P
G
B
0.51
15.2
Yes
Yes
B
G
B
G
2.20
15.3'
Yes
Yes
B
B
B
G
0.827
20
20.1
Yes
NA**
F
P
F
B
0.28
20.2'
Yes
Yes
B
B
B
G
0.33
20.3
Yes
Yes
B
B
G
B
0.62
37/39/54
37.1
Yes
NA**
F
P
G
B
0
37.2*
Yes
Yes
B
B
B
G
1.75
37.3
Yes
Yes
B
B
B
G
3.38
56
56.1
Yes
NA**
G
P
F
B
0
56.2
Yes
Yes
B
G
G
G
0.71
56.3'
Yes
Yes
B
B
B
G
0.048
to
bo
* The State of California and the community concur on the selected remedial alternative asterisked for each of the Soil Operable Unit sites.
** ARARs do not have to be met unless a remedial action is taken.
P = Poor
F = Fair
G = Good
B = Best
NA = not applicable
ARAR = applicable or relevant and appropriate requirement
-------
Table 2-18. Comparative Analysis of Soil Operable Unit Remedial Alternatives (continued)
Evaluation
Criteria
Site
Number
Alternative
Overall Protection of Human
Health and the Environment
Compliance with ARARs
Long-Term Effectiveness and
Permanence
Reduction of Toiucity,
Mobility, and Volume
Short-Term Effectiveness
Implementabil ty
Present Worth Cost
($ millions)
57
57.1
Yes
NA*»
F
P
G
B
0
57.2
Yes
Yes
B
G
B
G
0.57
57.3'
Yes
Yes
B
B
B
G
1.01
59
59.1
Yes
NA**
F
P
F
B
0
59.21
Yes
Yes
B
B
B
G
0.087
59.3
Yes
Yes
B
B
G
G
0.63
60
60.1
Yes
NA**
F
P
P
B
0.003
60.2*
Yes
Yes
B
B
B
G
0.033
60.3
Yes
Yes
B
B
G
G
0.26
60.4
Yes
Yes
B
B
F
G
0.63
62
62.1
Yes
NA**
F
P
F
B
0.011
62.2
Yes
Yes
B
B
G
G
0.21
62.3'
Yes
Yes
B
B
B
G
0.049
65
65.1
Yes
NA**
F
P
G
B
0.004
65.2
Yes
Yes
B
B
B
G
0.186
65.3'
Yes
Yes
B
B
B
G
0.134
69
69.1
Yes
NA**
F
P
G
B
0.081
69.2'
Yes
Yes
B
B
B
B
0.45
to
u>
o
* The State of California and the community concur on the selected remedial alternative asterisked for each of the Soil Operable Unit sites.
** ARARs do not have to be met unless a remedial action is taken.
P = Poor
F = Fair
G = Good
B = Best
NA = not applicable
ARAR = applicable or relevant and appropriate requirement
-------
2.2.8.9 Community Acceptance
This is an assessment of the general public response to the Proposed Plan following review of
the public comments received on the RI Reports and FFS Report, during the public comment
period (from May 8 through June 7, 1995) and open community meeting (held on May 18,
1995). Section 7.0 of this ROD documents the community acceptance of the selected
remedies, as presented in the Responsiveness Summary.
2.2.9 The Selected Remedies
This section presents the remedies selected by the USAF, with concurrence by the USEPA and
the State of California, for each of the Soil OU sites which warrant cleanup. The selected
remedies were chosen based on the results of the comparative analysis of the alternatives
presented in Table 2-18 and provide the best trade-offs with respect to the nine evaluation
criteria. All design and construction of the selected remedial actions will be conducted by
certified professionals or under the supervision of certified professionals, as appropriate.
2.2.9. 7 Site 7/11 - "7100 Area" Disposal Site/Existing Fire Protect/on Training
Area
Alternative 7.3 was selected by the USAF, with concurrence by the USEPA and the State of
California, as the remedy for Site 7/11. The major components of this remedy include:
• filling in the depression at Site 7 with inert fill
• treating the contaminated shallow and deep soils at Sites 7 and 11 by in situ
bioremediation and possibly soil vapor extraction (SVE). The in situ
bioremediation system could be converted to a SVE system if significant
amounts of solvents are encountered, in order to speed up remediation;
• installing a prescriptive landfill cover over the Site 7 impacted area if site
conditions indicates it is appropriate, or a vegetative cover if there is no threat
to ground water quality nor generation of landfill gases, using inert soils and/or
non-designated soils to construct the foundation for the cap/cover; and
• monitoring the groundwater (if contamination remains in place that threatens
groundwater quality).
Remediation at Site 7/11 will be implemented in a phased approach, whereby SVE,
bioventing, and soil gas monitoring will be implemented prior to a final determination on the
need for a prescription landfill cover pursuant to Article 8 of 23 California Code of
-------
Regulations (CCR), Division 3, Chapter 15. Once the SVE/bioventing system has been
operated until it has met cleanup standards, or design goals as appropriate, or has otherwise
reached technical or economic limitations, a determination will be made whether a continuing
source of methane or trace gases exist, and whether a significant threat to groundwater quality
exists.
The Air Force will conduct further soil gas sampling at this site to define the extent of VOC
contamination, as part of the remedial design work. The feasibility of SVE will be evaluated
when it is demonstrated that soil contaminants may cause concentrations in the leachate to
exceed the aquifer cleanup levels, based on an interpretation of soil gas data using VLEACH
or another appropriate vadose zone model.
The actual decision on whether to build and operate an SVE system will depend on the degree
to which the contamination presents a threat to ground water and whether site characteristics
are suitable for the SVE technology. It is generally preferable from a technical and cost
perspective to clean up contamination in the vadose zone before it reaches the ground water.
The feasibility analysis will be prepared by the Air Force as a primary document. The
decision will be made by the signatory parties to the FFA and will be based, at a minimum, on
the following factors:
a. the cost and time associated with the predicted additional groundwater remediation if
no SVE is implemented;
b. the cost of implementing the SVE system to meet the SVE soil cleanup standard;
c. the incremental cost over time of vadose zone remediation compared to the incremental
cost of groundwater remediation, on the basis of a common unit (e.g., cost to remove a
pound of TCE), provided that the underlying groundwater has not reached aquifer
cleanup levels;
d. the results of VLEACH or another appropriate vadose zone model, in conjunction with
a groundwater fate and transport model to predict the resulting concentration from the
vadose zone contamination in the nearest groundwater wells monitoring the site;
e. the results of VLEACH or another appropriate vadose zone model, that interprets soil
gas data, to predict the mass and concentration of discharges from the vadose zone to
the groundwater;
RL/10-95/ES/1260005.AWS
2-32
-------
This demonstration is to be made prior to operation of the bioventing system in areas
considered for SVE (to prevent interference from bioventing). Once SVE is initiated, it will
be terminated in accordance with the demonstration required for Site 57 (Section 2.2.9.7).
The need to implement the bioventing remedy will be reevaluated when SVE is terminated.
Initial site grading will be accomplished in conjunction with drilling in order to allow site
access for the drill rigs; the Site 7 depression may or may not be filled above grade at this
time. Further grading may be accomplished to minimize infiltration of surface water into Site
7 during SVE and bioventing. Final site construction will be accomplished at the completion
of SVE and bioventing consistent with the determination of the type of cap or cover that is
required at Site 7.
Capital cost estimates for this remedy are projected at approximately $2.7 million, operation
and maintenance costs are estimated at $2.0 million. Total cost, represented as a net present
worth using a five percent discount rate, is calculated at $3.69 million.
The basis for cleanup at Site 7/11 is compliance with ARARs for waste disposal sites,
mitigating a likely source of groundwater contamination, and protection of groundwater
quality for its beneficial use. Table 2-19 presents the Site 7/11 cleanup levels.
Table 2-19. Site 7/11 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Subsurface Soils
TPH as Diesel
TPH as Gasoline
10
1
TPH = total petroleum hydrocarbon
ppm = parts per million
2.2.9.2 Site 13 - Drainage Ditch Number 1
Alternative 13.3 was selected by the USAF, with concurrence by the USEPA and State of
California as the remedy for Site 13. The major components of this remedy include:
removing surface water, if present, by pumping and discharging to the publicly
owned treatment works (POTW);
excavating approximately 1,900 cubic yards (yd3) of contaminated sediments
and surface soils to remove all contamination above acceptable levels;
2-33
-------
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site, and monitoring surface water if contamination that threatens
surface water quality remains at the site.
Capital cost estimates for this remedy are projected at approximately $100,000, operation and
maintenance costs are estimated at $212,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $279,000.
The basis for cleanup at Site 13 is protection of groundwater quality, surface water quality,
and ecological receptors. Table 2-20 presents the Site 13 cleanup levels.
Table 2-20. Site 13 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Water
Aluminum
Chromium
Lead
Manganese
Silver
Zinc
Sediment
Arsenic
Chromium
Chromium VI
Cobalt
Copper
Lead
Mercury
6.28
l.lx ID'2
9.4 x ID'3
l.OxlO-1
1.6 x 10-2
5.4 x 10-2
16
176
ND(O.l)
35
104
81
ND (0.2)
-------
Table 2-20. Site 13 Cleanup Levels (Continued)
Contaminant of Concern
Nickel
Vanadium
Zinc
4,4-DDD
4,4-DDE
4,4-DDT
Cleanup Level (ppm)
81
153
116
1.9
1.3
1.3
Sediment (Continued)
alpha-Chlordane
Dieldrin
gamma-Chlordane
3.4 x 10-'
2.8 x 10-2
3.4 x 10-'
Surface Soil
Arsenic
Benzo(a)anthracene
Benzo(g,h,i)perylene
Fluoranthene
Indeno(l ,2,3-cd)pyrene
Mercury
Naphthalene
Oil and Grease
Pyrene
TPH as Diesel
Zinc
16
3.3 x 10-'
3.3 x ID'1
3.3 x 10-1
3.3 x lO'1
ND (0.2)
3.3 x 10-'
430
3.3 x ID'1
100
1559
ppm = parts per million
TPH = total petroleum hydrocarbon
DDT = dichlorodiphenyltrichloroethane
ND = not detected
ODD = dichlorodiphenyldichloroethane
DDE = dichlorodiphenyldichloroethene
-------
2.2.9.3 Site 15 - Drainage Ditch Number 3
Alternative 15.3 was selected by the USAF, with concurrence by the USEPA and State of
California as the remedy for Site 15. The major components of this remedy include:
• removing surface water, if present, by pumping and discharging to the POTW;
• excavating approximately 4,300 yd3 of contaminated sediments to remove all
contamination above acceptable levels;
• transporting the sediments to the on-base ex situ bioremediation facility;
• treating the excavated sediments by ex situ bioremediation as appropriate;
• transporting the treated sediments to, and consolidating them with landfill cap
foundation materials at Site 7, as appropriate; and
• monitoring the surface water if contamination that threatens surface water
quality remains at the site.
Capital cost estimates for this remedy are projected at approximately $229,000, operation and
maintenance costs are estimated at $682,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $827,000.
The basis for cleanup is protection of groundwater/surface water quality and ecological
receptors. Table 2-21 presents the Site 15 cleanup levels.
Table 2-21. Site 15 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Water
Chromium
Lead
Manganese
Vanadium
Zinc
Sediment
Barium
Cadmium
l.lxlO-2
9.4 x 10-3
1.0x10-'
1.0x10-'
5.4 x 10-2
1300
1.4
2-36
-------
Table 2-21. Site 15 Cleanup Levels (Continued)
Contaminant of Concern
Cleanup Level (ppm)
Sediment (Continued)
Chromium
Chromium VI
Copper
Lead
Mercury
Zinc
Acenaphthene
Acenaphthylene
alpha-Chlordane
Anthracene
Aroclor 1248
Aroclor 1254
Aroclor 1260
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g , h , i)pery lene
Benzo(k)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Dieldrin
Fluoranthene
Fluorene
gamma-Chlordane
Indeno(l,2,3-cd)pyrene
Naphthalene
Oil and Grease
176
ND(O.l)
104
81
ND (0.2)
116
3.3 x 1C'1
3.3 x ID'1
3.4 x 10-'
3.3 x 10-'
6.6 x lO'2
6.6 x ID'2
6.6 x ID'2
3.3 x 10-'
3.3 x 10-'
3.3 x 10-'
3.3 x 10-'
3.3 x 10-'
3.3 x 10-'
3.3 x 10-'
2.8 x 10-2
3.3 x 10-'
3.3 x 10-'
3.4 x 10-'
3.3 x 10-'
3.3 x 10''
430
2-37
-------
Table 2-21. Site 15 Cleanup Levels (Continued)
Contaminant of Concern
Cleanup Level (ppm)
Sediment (Continued)
Phenanthrene
Pyrene
TPH as Diesel
TPH as Gasoline
3.3 x 10-'
3.3 x 10'1
10
1
TPH = total petroleum hydrocarbon ppm = parts per million
ND = not detected
2.2.9.4 Site 20 Sewage Treatment Plant
Alternative 20.2 was selected by the USAF, with concurrence by the USEPA and State of
California as the remedy for Site 20. The major components of this remedy include:
• excavating approximately 550 yd3 of TPH-contaminated shallow soils to remove
all contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 7, as appropriate;
• removing sludge and disposing as appropriate in accordance with 1994 RAM
for Site 20 (i.e. either disposal as hazardous waste, or treatment to render it
non-hazardous and non-designated for on-base disposal); and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $31,700, operation and
maintenance costs are estimated at $338,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $325,000.
The basis for cleanup of TPH-d is protection of groundwater quality; the basis for cleanup of
sludge is protection of human and ecological health. Table 2-22 presents the Site 20 cleanup
levels.
2-38
-------
Table 2-22. Site 20 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Soil (sludge location)
Lead
Mercury
Zinc
Subsurface Soil (diesel spill location)
TPH as Diesel
130
20
1559
10
TPH = total petroleum hydrocarbon
ppm = parts per million
2.2.9.5 Site 37/39/54 - Building 3389/Hazardous Waste Control Storage
Alternative 37.2 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for Site 37/39/54. The major components of this remedy include:
• excavating approximately 220 yd3 of contaminated surface soils to remove all
contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 7, as appropriate;
• treating the contaminated shallow and deep soils by in situ bioremediation and
possible SVE. The in situ bioremediation system could be converted if
appropriate, to an SVE system if significant amounts of solvents are
encountered in order to speed up remediation; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
The Air Force will conduct further soil gas sampling at this site to define the extent of VOC
contamination, as part of the remedial design work. The feasibility of SVE will be evaluated
when it is demonstrated that soil contaminants may cause concentrations in the leachate to
exceed the aquifer cleanup levels, based on an interpretation of soil gas data using VLEACH
or another appropriate vadose zone model.
RL/10-95/ES/1260005.AWS
2-39
-------
The actual decision on whether to build and operate an SVE system will depend on the degree
to which the contamination presents a threat to ground water and whether site characteristics
are suitable for the SVE technology. It is generally preferable from a technical and cost
perspective to clean up contamination in the vadose zone before it reaches the ground water.
The feasibility analysis will be prepared by the Air Force as a primary document. The
decision will be made by the signatory parties to the FFA and will be based, at a minimum, on
the following factors:
a. the cost and time associated with the predicted additional groundwater remediation if
no SVE is implemented;
b. the cost of implementing the SVE system to meet the SVE soil cleanup standard;
c. the incremental cost over time of vadose zone remediation compared to the incremental
cost of groundwater remediation, on the basis of a common unit (e.g., cost to remove a
pound of TCE), provided that the underlying groundwater has not reached aquifer
cleanup levels;
d. the results of VLEACH or another appropriate vadose zone model, in conjunction with
a groundwater fate and transport model to predict the resulting concentration from the
vadose zone contamination in the nearest groundwater wells monitoring the site;
e. the results of VLEACH or another appropriate vadose zone model, that interprets soil
gas data, to predict the mass and concentration of discharges from the vadose zone to
the groundwater;
This demonstration is to be made prior to operation of the bioventing system in areas
considered for SVE (to prevent interference from bioventing). Once SVE is initiated, it will
be terminated in accordance with the demonstration required for Site 57 (Section 2.2.9.7).
The need to implement the bioventing remedy will be reevaluated when SVE is terminated.
Capital cost estimates for this remedy are projected at approximately $509,000 operation and
maintenance costs are estimated at $1,709,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $1,757,000.
The basis for cleanup is protection of groundwater quality. Table 2-23 presents the
Site 37/39/54 cleanup levels.
RL/10-95/ES/1260005.AWS
2-40
-------
Table 2-23. Sites 37/39/54 Cleanup Levels
Contaminant of Concern*
Cleanup Level (ppm)
SITE 37
Subsurface Soil
Oil and Grease
TPH as Diesel
TPH as Gasoline
430
10
1
SITE 39
Surface Soil
Oil and Grease
TPH as Diesel
Subsurface Soil
Benzene
Ethylbenzene
Toluene
TPH as Diesel
TPH as Gasoline
Xylene
430
100
1 x 10'1
2.9
4.2
10
1
1.7
SITE 54
Subsurface Soil
Benzene
TPH as Gasoline
1 x 10-'
1
TPH = total petroleum hydrocarbon
ppm = parts per million
During the Additional Site Characterization field effort (IT Corp., 1996) chlorinated solvents were
detected hi the soil samples. However, these constituents and their corresponding cleanup goals are not
presented hi this Record of Decision. Any additional contaminants of concern and associated cleanup
levels will be incorporated into the remedial design per Section 2.2.9.5 and documented hi the Feasibility
Study Report and Record of Decision for the Final Operable Unit.
-------
2.2.9.6 Site 56 - Oil/Water Separator 2989
Alternative 56.3 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for Site 56. The major components of this remedy include:
• excavating approximately 1,110 yd3 of contaminated surface and shallow soils
to remove all contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 4 or Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $36,000, operation and
maintenance costs are estimated at $12,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $48,000.
The basis for cleanup is protection of human health and groundwater quality. Table 2-24
presents the Site 56 cleanup levels.
Table 2-24. Site 56 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Soil
Arsenic
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Lead
Oil and Grease
TPH as Diesel
22
3.3 x lO'1
3.3 x 10-'
3.3 x ID'1
3.3 x 10-'
3.3 x lO'1
130
430
100
-------
Contaminant of Concern
Cleanup Level (ppm)
Subsurface Soil
Oil and Grease
TPH as Diesel
TPH as Gasoline
430
100
5
TPH = total petroleum hydrocarbon
ppm = parts per million
2.2.9.7 Site 57 - Oil/Water Separator 7019
Alternative 57.3 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for Site 57. The major components of this remedy include:
• treating the contaminated shallow and deep soils by hi situ SVE; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
The goal of cleaning up the vadose zone is to minimize further degradation of the groundwater
by the contaminants hi the soil. It is generally preferable from a technical and cost perspective
to clean up contamination in the vadose zone before it reaches the groundwater. The soil
cleanup standard will be achieved when the residual vadose zone contaminants will not cause
the groundwater cleanup standard, as measured in groundwater wells monitoring the plume, to
be exceeded after the cessation of the groundwater remediation. The Air Force will make the
demonstration that the standard has been met through contaminant fate and transport modeling,
trend analysis, mass balance, and/or other means. This demonstration will include
examination of the effects of the residual vadose zone contamination in the groundwater using
VLEACH or another appropriate vadose zone model, hi conjunction with a groundwater fate
and transport model, to predict the resulting concentration from this residual vadose zone
contamination hi the nearest groundwater wells monitoring the site. This demonstration can be
made prior to the cessation of groundwater remediation. The Ah" Force shall provide
verification, through actual data, that the above standard has been met. The signatory parties
to this Record of Decision (ROD) will jointly make the decision that the soil cleanup standard
has been met.
The Air Force shall operate the SVE system until it makes the demonstration that the cleanup
standard, set forth above, has been met. The Air Force shall continue to operate the SVE
system if appropriate, after considering the following factors:
-------
a) Whether the predicted concentration of the leachate from the vadose zone (using
VLEACH or another appropriate vadose zone model that interprets soil gas data) will
exceed the ground water cleanup standard;
b) Whether the mass removal rate is approaching asymptotic levels after temporary
shutdown periods and appropriate optimization of the SVE system;
c) The additional cost of continuing to operate the SVE system at concentrations
approaching asymptotic mass levels;
d) The predicted effectiveness and cost of further enhancements to the SVE system (e.g.,
additional vapor extraction wells);
e) Whether the cost of groundwater remediation will be significantly more if the residual
vadose zone contamination is not addressed;
f) Whether residual mass in the vadose zone will significantly prolong the time to attain
the ground watercleanup standard; and
g) The incremental cost over time of vadose zone remediation compared to the
incremental cost over time for groundwater remediation on the basis of a common unit
(e.g., cost of pound of TCE removed) provided that the underlying groundwater has
not reached aquifer cleanup levels.
The signatory parties agree that the Air Force may cycle the SVE system on and off in order
to optimize the SVE operation and/or to evaluate the factors listed above.
The signatory parties to this ROD will jointly make the decision that the SVE system may be
shut off. If the parties cannot reach a joint resolution, any party may invoke dispute
resolution. This ROD does not resolve the ARAR status of State requirements regarding the
establishment of soil cleanup levels. The parties agree that hi the event of a dispute regarding
SVE shutoff, the State may argue its authority to require soil cleanup (including soil cleanup
standards) as the basis for continuing operation of the SVE system, based on the above factors.
Capital cost estimates for this remedy are projected at approximately $852,000, operation and
maintenance costs are estimated at $168,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $1,012,000.
AA
-------
The basis for cleanup is protection of groundwater quality.
Table 2-25. Site 57 Cleanup Level
Contaminant of Concern
Cleanup Level
Subsurface Soil
Trichloroethene
See text in Section 2.2.9.7
2.2.9.8 Site 59 - Oil/Water Separator 4251
Alternative 59.2 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for Site 59. The major components of this remedy include:
• excavating approximately 1,200 yd3 of contaminated shallow soils to remove all
contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 4 or Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $64,000, operation and
maintenance costs are estimated at $24,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $87,000.
The basis for cleanup is protection of groundwater quality. Table 2-26 presents the Site 59
cleanup levels.
Table 2-26. Site 59 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Subsurface Soil
TPH as Diesel
TPH as Gasoline
10
1
TPH = total petroleum hydrocarbon ppm = parts per million
-------
2.2.9.9 Site 60 - Oil/Water Separator 6900
I Alternative 60.2 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for Site 60. The major components of this remedy include:
• excavating approximately 350 yd3 of contaminated shallow soils to remove all
contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 4 or Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $23,000, operation and
maintenance costs are estimated at $11,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $33,000.
The basis for cleanup is protection of groundwater quality. Table 2-27 presents the Site 60
cleanup levels.
Table 2-27. Site 60 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Subsurface Soil
TPH as Gasoline
Xylenes
5*
17
TPH = total petroleum hydrocarbon ppm = parts per million
* If contamination is found to exist below the limits excavation, the remedial action and cleanup level will be
reevaluated.
2.2.9.10 Site 62 - Oil/Water Separator 7110 and Jet Engine Test Cell
(Facility 7099)
Alternative 62.3 was selected by the USAF, in concurrence by the USEPA and the State of
California as the remedy for Site 62. The major components of the remedy include:
2-46
-------
• excavating approximately 500 yd3 of contaminated surface and shallow soils to
remove all contamination above acceptable levels;
• transporting the excavated soils to the on-base ex situ bioremediation facility;
• treating the excavated soils by ex situ bioremediation as appropriate;
• transporting the treated soils to, and consolidating them with landfill cap
foundation materials at Site 4 or Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $29,000, operation and
maintenance costs are estimated at $23,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $49,000.
The basis for cleanup is protection of ecological receptors, human health, and groundwater
quality. Table 2-28 presents the Site 62 cleanup levels.
Table 2-28. Site 62 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Soil
Benzo(k)fluoranthene
Cadmium
Fluoranthene
Lead
Naphthalene
Pyrene
TPH as Diesel
Zinc
3.3 x lO'1
9
3.3 x lO'1
130
3.3 x 10-'
3.3 x ID'1
10
1559
9.-47
-------
Table 2-28. Site 62 Cleanup Levels (Continued)
Contaminant of Concern
Cleanup Level (ppm)
Subsurface Soil
Benzo(a)pyrene
TPH as Diesel
3.3 x 10-'
10
TPH = total petroleum hydrocarbon
ppm = parts per million
2.2.9.11 Site 65 - Oil/Water Separator 6910
Alternative 65.3 was selected by the USAF, in concurrence by the USEPA and the State of
California as the remedy for Site 65. The major components of the remedy include:
• excavating approximately 900 yd3 of contaminated surface and shallow soils to
remove all contamination above acceptable levels;
• transporting the excavated surface soils to an off-base disposal facility;
• transporting the excavated shallow soils to the on-base ex situ bioremediation
facility;
• treating the excavated shallow soils by ex situ bioremediation as appropriate;
• transporting the treated soils, and consolidating them with landfill cap
foundation materials at Site 4 or Site 7, as appropriate; and
• monitoring the groundwater if contamination that threatens groundwater quality
remains at the site.
Capital cost estimates for this remedy are projected at approximately $114,000, operation and
maintenance costs are estimated at $22,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $134,000.
The basis for cleanup is protection of groundwater quality. Table 2-29 presents the Site 65
cleanup levels.
RL/10-95/ES/1260005.AWS
2-48
-------
Table 2-29. Site 65 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Soil
Chromium
Lead
Oil and Grease
TPH as Diesel
Subsurface Soil
TPH as Diesel
TPH as Gasoline
210
130
430
10
10
1
TPH = total petroleum hydrocarbon
ppm = parts per million
2.2.9. 72 Site 69 - Open Burn/Open Detonation Area
Alternative 69.2 was selected by the USAF, in concurrence by the USEPA and the State of
California as the remedy for Site 69. The major components of the remedy include:
• removing surface water, if present, by pumping and discharging to the POTW;
• excavating approximately 8,680 yd3 of contaminated sediments and surface soils
to remove all contamination above acceptable levels;
• transporting the excavated sediments and surface soils to, and consolidating
them with landfill cap foundation materials at Site 4, as appropriate; and
• monitoring surface water as appropriate if contamination remains at the site that
threatens surface water quality.
Capital cost estimates for this remedy are projected at approximately $370,000, operation and
maintenance costs are estimated at $93,000. Total cost, represented as a net present worth
using a five percent discount rate, is calculated at $451,000.
The basis for cleanup is protection of human health, ecological receptors, and surface water
quality. Table 2-30 presents the Site 69 cleanup levels.
2-49
-------
Table 2-30. Site 69 Cleanup Levels
Contaminant of Concern
Cleanup Level (ppm)
Surface Water
Barium
Manganese
Sediment
OCDD
OCDF
Total HPCDD
Total HPCDF
Total HXCDD
Total HXCDF
Total PCDD
Total PCDF
Total TCDF
1
1.0x10-'
5 x lO'6
total 2,3,7,8-TCDD equivalent
Surface Soil
Barium
Manganese
Zinc
1754
(A)
1559
DI /in OC/CC/11JWYK
2-50
-------
Table 2-30. Site 69 Cleanup Levels (Continued)
Contaminant of Concern
Cleanup Level (ppm)
Surface Soil (continued)
OCDD
OCDF
Total HPCDD
Total HPCDF
Total HXCDD
Total HXCDF
Total PCDD
Total PCDF
Total TCDF
2x10-"
total 2,3,7,8-TCDD equivalent
(A) Manganese was a contaminant of concern (COC) in the Focused Feasibility Study Report; however, revised
natural background concentration is 5720 ppm. The maximum concentration detected was 1430 ppm; therefore,
manganese is no longer a COC.
ppm = parts per million HPCDD = heptachlorodibenzo-p-dioxin
HPCDF = heptachlorodibenzofuran HXCDD = hexachlorodibenzo-p-dioxin
HXCDF = hexachlorodibenzofuran OCDD = octachlorodibenzo-p-dioxin
OCDF = octachlorodibenzofuran TCDD = tetrachlorodibenzo-p-dioxin
TCDF = tetrachlorodibenzofuran PCDD = pentachlorodibenzo-p-dioxin
PCDF = pentachlorodibenzofuran
2.2.10 Statutory Determinations
The selected remedies satisfy the statutory requirements in CERCLA Section 121(b), as
amended by SARA, in that the following mandates are attained:
the selected remedies are protective of human health and the environment, will
decrease site risks, and will not create short-term risks nor have cross-media
consequences;
the selected remedies comply with federal and state requirements that are
applicable, or relevant and appropriate, to the remedial actions;
the selected remedies are cost-effective in their fulfillment of the nine CERCLA
evaluation criteria; and
the selected remedies utilize permanent solutions to the maximum extent
practicable.
-------
-------
3.0 Soil Operable Unit Sites Selected for No Further Action
3.1 Declaration for the Soil Operable Unit Sites Selected for No Further Action
No Further Action is Necessary to Ensure
Protection of Human Health and the Environment
3.1.1 Site Name and Location
Soil OU Sites (IRP Sites) Selected for No Further Action
Mather AFB (a NPL Site),
Sacramento County, California
3.1.2 Statement of Basis and Purpose
The Soil OU sites for which no further action was chosen at the formerly active Mather AFB
were investigated under the Mather AFB IRP and are described and evaluated in the RI/FS
documents. These sites include: Site 9 - Fire Department Training Area Number 2, Site 10 -
Fire Department Training Area Number 3, Site 14 - Drainage Ditch Number 2, Site 16 -
Electron Tube Burial Site, Site 21 - Asphalt Rubble Storage Site, Site 22 - Asphalt Rubble
Storage Site, Site 24 - JP-4 Spill Site/Refueling Apron, Site 26 - Building 10072 UST, Site 27
- Building 10060 UST, Site 28 - Building 16100 UST, Site 31 - Building 10090 UST, Site 33 -
Building 3308 USTs, Site 38 - Building 3388, Site 40 - Building 3875 UST, Site 41 - Building
2995 USTs, Site 42 - Building 2898 UST, Site 43 - Building 10150 USTs, Site 44 - Building
8540 UST, Site 45 - Building 7003 UST, Site 46 - Building 8158 UST, Site 48 - Building
10410 USTs, Site 49 - Building 10450 UST, Site 51 - Building 10030 UST, Site 52 - Building
10400 UST, Site 53 - Building 18501 UST, Site 55 - OWS 7038, Site 58 - OWS 4771, Site 61
- OWS 6905, Site 63 - OWS 3221 and USTs, Site 64 - OWS 4120, Site 66 - OWS 6915, Site
A - Building 1226 UST, Site C - Building 3975 UST, Site E - Building 10015 UST, Site F -
Building 10065 UST, Site G - Building 18018 UST, Site H - Building 18020 UST and
Building 18011 UST, and Site I - Building 4853 UST. These remedial actions were chosen in
accordance with CERCLA, as amended by SARA, and to the extent practicable, the NCP.
These decisions are based on the Administrative Record for these sites.
The USEPA Region IX and the State of California concur that no action is necessary at these
sites to ensure protection of human health and the environment.
-------
3.1.3 Description of the No Further Action Decision
Cleanup options were not developed for sites which were previously clean-closed or
recommended for clean-closure by Sacramento County (i.e., USTs already removed) or for
which no COCs were identified. Based on the human health risk assessment, all cancer risks
are within or below the acceptable range of 1 x 10^ to 1 x 10"6 and all non-cancer risks have a
hazard index of less than 1.0 in their current state. Therefore, the USAF is not proposing
cleanup or further investigative activities. These no further action sites include: Sites 9, 10,
14, 16, 21, 22, 24, 26, 27, 28, 31, 33, 38, 40, 41, 42, 43, 44, 45, 46, 48, 49, 51, 52, 53, 55,
58, 61, 63, 64, 66, A, C, E, F, G, H, and I.
3.1.4 Summary of Site Risks
Remedial investigation activities at Mather AFB included fate and transport modeling and the
MBRA [IT 1995d]. The data collected and utilized in the RIs and FFS were of USEPA
quality Level HI, IV, or V, or equivalent [USEPA 1987]. Formal data validation of the
RI- and FFS-generated data was performed to ensure that data were of the quality
commensurate with their intended use.
Based on the human health risk assessment, all cancer risks for the sites described in this no
further action section are within or below the acceptable range of 1 x 10"4 to 1 x 10"6, and all
non-cancer risks have a hazard index less than 1.0 in their current state.
3.1.4.1 Human Health Risks
Analytes detected in the course of the RI activities at Mather AFB were subjected to a
multi-step screening process to determine COCs. The following steps were employed in the
COC determination process for the Soil OU sites and are described in Section 2.2.6.1.
• initial screening methods prescribed by USEPA guidance;
• comparison to background;
• comparison to ARARs;
• comparison to analytical method quantitation limit;
• evaluation of operational history (i.e., process knowledge); and
• evaluation of estimated risk to human and ecological receptors.
3.2 Decision Summary for Soil OU Sites Selected for No Further Action
3.2.1 Site Name, Location, and Description
The Soil OU sites selected for no further action at the formerly active base are presented in
Figure 3-1 and in Section 3.1.2.
-------
Rgure 3-1. Soil Operable Unit Sites Selected for No Further Action
SCALE
SOIL OPERABLE UNIT SITE SELECTED FOR NO FURTHER ACTION
0
3000 6000 FEET
-------
3.2.2 Site History and Enforcement Activities
Previous investigations have been conducted at the Soil OU sites selected for no further action
as part of the USAF IRP and are presented in Table 3-1.
3.2.3 Highlights of Community Participation
The public participation requirement of CERCLA Sections 113(k)(2)(B)(I-v) and 117 were met
through a public comment period (held May 8 through June 7, 1995) and a public meeting
(held on May 18, 1995) to address the Proposed Plan and content of supporting RI/FS
documents in the selection of the no further action sites.
3.2.4 Scope and Role of Response Action
Since these sites have been clean-closed or recommended to Sacramento County for
clean-closure, or no COCs were identified, this section of the ROD presents the no further
action alternative as the planned response action. No unacceptable risk to human health or the
environment exists at these sites.
3.2.4. 7 Description of the "No Action" Alternative
Cleanup options were not developed for sites which were previously clean-closed by
Sacramento County or recommended for clean-closure (i.e., UST already removed to
Sacramento County), or for which no COCs were identified. Since no risk to human health or
the environment exists at these sites, the USAF is not proposing cleanup or further
investigative activities. The no action alternative will not involve any long-term monitoring.
3.2.5 Summary of Site Characteristics
A brief description of each of the no further action sites is provided in the following sections.
3.2.5.1 Site 9 - Fire Department Training Area Number 2
Site 9 was used as a fire-training area between 1945 and 1947 and is reportedly located west of
the Base Operations Building, underneath the aircraft parking ramp. Exercises were
conducted daily in a cleared area within an earthen berm. Approximately 50 to 250 gallons of
POL waste were reportedly used per exercise, with some solvents being possibly commingled
with the POL waste. The location of Site 9 has not been found on historic air photographs,
nor has any other evidence indicated where this site was situated. Consequently, no sampling
has been conducted. Because the site cannot be located, no further action will be conducted
under CERCLA.
-------
Table 3-1. Previous Investigations at the No Further Action Sites
SITE NUMBER
9
10
14
16
21
22
24
26
27
28
31
33
38
40
41
42
43
44
45
46
48
49
51
52
53
55
58
61
63
64
66
A
C
E
F
G
H
I
APPLICABLE INVESTIGATION
1, 11, 12
1,2,4,5,6, 11, 12
1,2,3,4,5,6,7, 10, 11, 12
1,4,5,7, 11, 12
1,4, 11, 12
1, 11, 12
4,5,7,11,12
1,4,5,6,7,9, 11, 12
1,7, 11, 12
1,7, 11, 12
9, 11, 12
9, 11, 12
9, 11, 12
9, 11, 12
9, 11, 12
9, 11, 12
9, 10, 11, 12
9, 11, 12
11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
5,8, 11, 12
5,8, 11, 12
8, 11, 12
5,8,9, 10, 11, 12
5,8, 11, 12
5,8, 11, 12
9, 10, 11, 12
7,9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
9, 10, 11, 12
1. Installation Restoration Program (IRP) Records Search for Mather Air Force Base, Phase I [CH2M-HiIl, Inc. 1982];
2. IRP Phase II, Stage 2 Investigation [AeroVironment 1987];
3. IRP Phase II, Stage 3 Investigation [AeroVironment 1988];
4. Well Redevelopment and Sampling Plan [IT 1988a];
5. Quarterly Routine Groundwater Sampling [IT 1993g] and [EA 1990a-c];
6. Site Inspection Report [IT 1990a];
7. Group 2 Sites Remedial Investigation Report [IT 1992a];
8. Group 3 Sites Technical Memorandum [IT 1993a];
9. Underground Storage Tank Closure Reports [IT 1990b and IT 1993c-d];
10. Soil Operable Unit (OU) and Groundwater OU Additional Field Investigation Report [IT 1994a];
11. Mather Baseline Risk Assessment Report [IT 1995d]; and
12. Groundwater OU and Soil OU Focused Feasibility Study Report [IT 1995a].
RL/10-95/ES/1260005.AWS
3-5
-------
3.2.5.2 Site 10 - Fire Department Training Area Number 3
Site 10 is the assumed location of a fire-training area used between 1947 and 1958, and is
located under the SAC refueling tanker loading apron. Approximately 100 to 500 gallons of
POL waste, possibly commingled with solvents, were used per exercise. Investigations of this
site have revealed no COCs. However, another location, just north of the former refueling
apron, was found in 1994, and is now thought to be the actual location of the fire-training
area. The new location, called Site IOC, was investigated in 1995 and will be included in the
Final OU.
3.2.5.3 Site 14 - Drainage Ditch Number 2
Site 14 is an unlined drainage ditch located in the north-central portion of the base between
Building 2950 and the former motor pool area. During the late 1960s, waste oils and solvents
were reportedly dumped directly into the ditch. The ditch drains off-base and feeds a
south-trending ditch that reenters the base at Site 13. Investigations have revealed no COCs.
3.2.5.4 Site 16 - Electron Tube Burial Site
Site 16 is located in the SAC area, directly under Building 8170. In the late 1950s,
approximately sixty low-level radioactive electron tubes were reportedly buried in 15-foot
auger holes. The electron tubes were placed inside one-gallon containers and encased in
concrete. Investigations have revealed no radiation at the surface above background levels,
nor in nearby groundwater from Well MAFB-18. There is no significant health risk due to
exposure to the intact concrete containing the electron tubes. Future landowners or lessees
will be notified that any excavation at the site should proceed with caution to avoid inadvertent
exposure to broken concrete containers and/or electron tubes.
3.2.5.5 Site 21 - Asphalt Rubble Storage Site
Site 21 is located in two discrete areas northeast of Site 20. Asphalt and concrete rubble were
stored on the ground in the two areas within the site. Site 21 did not reportedly receive any
hazardous waste. Known disposal practices indicated no disposal of contaminants, and visual
inspections were consistent with disposal of inert construction rubble only.
3.2.5.6 Site 22 - Asphalt Rubble Storage Site
Site 22 is located east of the sewage treatment plant. Asphalt and concrete rubble were stored
on the ground at the site. Site 22 reportedly did not receive any hazardous waste. Known
RL/IO-95/ES/1260005.AWS 3-6
-------
disposal practices indicated no disposal of contaminants, and visual inspections were consistent
with disposal of inert construction rubble only.
3.2.5.7 Site 24 - 1983 JP-4 Spill and Refueling Apron
Site 24 consists of the SAC aircraft refueling tanker loading apron and an adjacent low, grassy
area located south and west of the loading area. In 1983, approximately 8,000 gallons of JP-4
were spilled on the concrete tanker loading area during refueling operations. Some of the fuel
was reportedly washed by rainwater onto adjacent unpaved areas. Investigations have revealed
no COCs.
3.2.5.8 Site 26 - Building 10072, One Abandoned UST
Site 26 is located in the extreme southwest corner of the base. The site had a 250-gallon UST
which stored motor gasoline. The tank and its associated piping were installed in 1956 and
removed in 1987. Investigations have revealed no COCs. This site has been recommended to
Sacramento County for clean-closure.
3.2.5.9 Site 27 - Building 10060, One Abandoned UST
Site 27 is located in an ungraded, grassy area between the runways and the former base
housing. A steel 379-gallon diesel fuel UST was installed at the site in 1954 and removed in
1987. Investigations have revealed no COCs. This site has been recommended to Sacramento
County for clean-closure.
3.2.5.10 Site 28 - Building 16100, One Abandoned UST
Site 28 is located on the western edge of an open area between the former Wherry and
Capehart housing, adjacent to base housing well FH-6. The site had a steel 218-gallon motor
gasoline UST which was installed in 1968 and removed in 1987. Investigations have revealed
no COCs. This site has been clean-closed by Sacramento County.
3.2.5. 7 7 Site 31 - Building 10090, One Abandoned UST
Site 31 is approximately 2,000 feet east of Site 7. This site contained a 250-gallon steel UST
that stored motor gasoline for emergency power generation. The tank was installed in 1954
and removed in December 1987. During excavation, a strong hydrocarbon odor was noted,
and a "black scum" and "film of gasoline" were observed on the surface of water seeping into
the excavation. Water was encountered 2 to 3 feet bis during excavation. The water
encountered in the excavation was probably perched-water above a low permeability soil
7 7
RL/10-95/ES/1260005.AWS J '
-------
horizon. The quantity of fuel lost at the site is unknown. This site has been recommended to
Sacramento County for clean-closure. The Air Force intends to excavate limited soil at this
site to remove easily removable contaminated soils.
3.2.5.12 Site 33 - Building 3308, Six Abandoned USTs
This site is located in the Main Base area, approximately 900 feet southwest of Site 32. This
site contained one 3,600-gallon and five 1,500-gallon USTs that were used to store gasoline
and mineral spirits. The tanks were installed in 1942. The tanks were reportedly taken out of
service in 1961 and were removed in December 1988. During excavation, strong solvent
odors were noted, and one of the tanks contained residual hydrocarbons.
Prior to completing the excavation, the hydrocarbons (approximately 540 gallons) were
removed from the tank and transported to a recycling facility. Approximately 400 cubic yards
of contaminated soil were removed from the site, incinerated, and disposed of on-base. The
excavation was backfilled with clean crushed rock and then covered with four-inch thick
asphalt paving. Potentially contaminated soil next to existing structures and buildings was not
removed due to limited access; the Air Force will consider excavating additional soil under the
building awning if consistent with building use or property transfer.
3.2.5.13 Site 38 - Building 3388
Site 38 consists of Building 3388 located near the intersection of Fourth Street and Air Corps
Way. Two steel 5,000-gallon tanks (Tanks 3390 and 3391) were used to store gasoline,
diesel, and alcohols from 1945 to 1977. This site has been recommended to Sacramento
County for clean-closure.
3.2.5.14 Site 40 - Building 3875, One UST
Site 40 is at Building 3875 near the intersection of Stratotanker Avenue and Femoyer Street.
A steel 570-gallon diesel fuel UST was installed in 1958 and removed hi 1988. Investigations
have revealed no COCs. This site has been clean-closed by Sacramento County.
3.2.5.15 Site 41 - Bui/ding 2995, Two USTs
Site 41 is at Building 2995 near Femoyer Street at the Old Motor Pool facility. This site had
two, steel 10,500-gallon USTs which stored gasoline and diesel from 1965 to 1977.
Investigations have revealed no COCs. The USTs were removed in 1989 and the site has been
clean-closed by Sacramento County.
RL/10-95/ES/1260005.AWS
3-8
-------
3.2.5.16 Site 42 - Building 2898, One UST
Site 42 is at Building 2898 located on Femoyer Street. This site had a steel 500-gallon UST
which stored aviation gasoline from 1967 until 1974-1975. Investigations have revealed no
COCs. The UST was removed in 1988 and the site has been clean-closed by Sacramento
County.
3.2.5.7 7 Site 43 - Building 10150, Two Abandoned USTs
Site 43 is located in the east-central portion of the base near the AC&W site. One tank was
removed in 1988 and the area clean-closed by Sacramento County. The second tank was
removed in 1993 and the site recommended to Sacramento County for clean-closure.
Investigations have revealed no COCs.
3.2.5.18 Site 44 - Building 8540, One UST
Site 44 consisted of a concrete 1,800-gallon UST located at Building 8540. The tank was used
to store oil and water starting in 1942 and was removed in 1988. This site has been
clean-closed by Sacramento County. Investigations have revealed no COCs.
3.2.5.19 Site 45 - Bui/ding 7003, One UST
Site 45 is at Building 7003 located at the old missile fueling facility. The tank was used to
store ammonia from the early 1960s until 1978 and was removed in 1988. This site has been
clean-closed by Sacramento County. Investigations have revealed no COCs.
3.2.5.20 Site 46 - Bui/ding 8158, One UST
Site 46 is at Building 8158 located in the northeast portion of the base, in the SAC Alert
Facility and consisted of a steel 250-gallon diesel fuel UST. The UST and its associated
piping were removed in 1993 and the site has been recommended to Sacramento County for
clean-closure. Investigations have revealed no COCs.
3.2.5.27 Site 48 - Building 10410, Two Abandoned USTs
Site 48 is at Building 10410 located in the east-central portion of the base near the AC&W
site. Site drawings indicate the presence of two USTs; however, a site inspection found only
one tank. The existing tank which contained gear oil and diesel fuel was removed in 1993 and
has been recommended to Sacramento County for clean-closure. Investigations have revealed
no COCs.
i o
RL/10-95/ES/I260005.AWS J~y
-------
3.2.5.22 Site 49 - Building 10450, One UST
Site 49 is located hi the east-central portion of the base near the AC&W facility. The site
consisted of a steel 8,500-gallon UST which contained gasoline and diesel. This tank was
removed hi 1993 and the site has been recommended to Sacramento County for clean-closure.
Investigations have revealed no COCs.
3.2.5.23 Site 51 - Building 10030, One UST
Site 51 is located hi the north-central portion of the base near the northeast end of
Runway 22L. The site consisted of a 275-gallon diesel fuel UST. The UST was removed in
1993 and the site has been recommended to Sacramento County for clean-closure.
Investigations have revealed no COCs.
3.2.5.24 Site 52 - Building 10400, One UST
Site 52 is located hi the east-central portion of Building 10400. The site was covered by
gravel, grass, and railroad-tie landscape border. The site consisted of a steel 4,000-gallon
diesel fuel UST. The UST was removed in 1993 and the site has been recommended to
Sacramento County for clean-closure. Investigations have revealed no COCs.
3.2.5.25 Site 53 - Building 18501, One UST
Site 53 is located in the southeast portion of the base, near Sites G and H and within the
former Weapons Storage Facility area. The site consisted of a 200-gallon diesel fuel UST.
The UST was removed hi 1993 and the site has been recommended to Sacramento County for
clean-closure. Investigations have revealed no COCs.
3.2.5.26 Site 55 - OWS 7038
Site 55 consisted of OWS 7038, located hi the western portion of the SAC area, approximately
120 feet west of Building 7035. Oil/water separator 7038 is a belt-type skimmer which
received aircraft washwater and discharges to the base sanitary sewer system. Prior to 1971,
OWS 7038 reportedly received TCE, PCE, antifreeze, methyl ethyl ketone, and methylene
chloride produced during maintenance operations. Investigations have revealed no COCs.
3.2.5.27 Site 58 - OWS 4771
Site 58 consists of OWS 4771 and is located hi the southeast portion of the Main Base at the
Army Helicopter washrack, approximately 450 feet east of Building 4677. Oil/water separator
4771 is a belt-type skimmer, constructed hi 1969, that received wastewater generated from the
^ 10
RL/IO-95/ES/1260005.AWS J lu
-------
washrack. The waste water reportedly contained fuels, oil and grease, hydraulic fluid,
PD-680, and antifreeze. Effluent from the OWS was discharged directly to the sanitary sewer
system. Investigations have revealed no COCs.
5.2.5.25 Site 61 - OWS 6905
Site 61 consists of an OWS that supports Building 7005, located in the SAC area.
Building 7005 was an aircraft maintenance hangar (referred to as the Fuel Cell), used for
aircraft fuel-system maintenance, which drained to OWS 6905. The OWS discharged directly
to the storm sewer system. It was reported that TCE, PCE, methyl ethyl ketone, and other
solvents were used hi Building 7005 in the 1960s and 1970s. Investigations have revealed no
COCs.
3.2.5.29 Site 63 - OWS 3321 and Two USTs
Site 63 is located in the northwest portion of the base and consisted of OWS 3321 at the South
Hobby Shop, northeast of Building 3320. Oil/water separator 3321 is a sump-type OWS that
received wastewater from the Automotive Hobby Shop and adjoining automotive component
steam-cleaning pad at Building 3320. The wastewater may have contained fuels, oils,
hydraulic fluid, antifreeze, cleaning fluids (containing trichloroethane, TCE, and methyl ethyl
ketone), and paint strippers (containing phenols and methyl chloride). Underground storage
tank 3320A was a 250-gallon waste oil tank, while UST 3320B was a 1,000 gallon waste oil
tank. The tanks were removed in 1993 and the tank sites have been recommended to
Sacramento County for clean-closure. Investigations have revealed no COCs.
3.2.5.30 Site 64 - OWS 4120
Site 64 consists of OWS 4120 and is located hi the far west portion of the Main Base at the
fuel tanker yard, approximately 240 feet northeast of Building 4120. Oil/water separator 4120
was a sump-type OWS that was constructed in the 1960s and received wastewater generated
from the fuel truck washrack yard. These wastewater contained fuels, oils, hydraulic fluids,
and antifreeze. Effluent from the OWS was discharged to the sanitary sewer system.
Investigations have revealed no COCs.
3.2.5.31 Site 66 - OWS 6915
Site 66 consists of OWS 6915 and is located in the central portion of the SAC area at the jet
engine repair shop, approximately 10 feet north of Building 7024. Oil/water separator 6915 is
a sump-type OWS, constructed in the early 1960s, which received wastewater from the jet
RUIO-95/ES/1260005.AWS
3-11
-------
engine repair shop. This wastewater contained fuels, oils, hydraulic fluid, and antifreeze.
Effluent from this OWS was discharged directly to the storm drain system. Investigations
have revealed no COCs. This site has been clean-closed by Sacramento County.
3.2.5.32 Site A
Building 1226 is the former Sierra Dining Hall located in the northwest portion of the base on
Lower Placerville Road. Tank 1226 was located on the southeast side of the building and was
reported to be a 4,000-gallon diesel fuel tank. Investigations have revealed no COCs. The
tank was removed hi 1993 and the site recommended to Sacramento County for clean-closure.
3.2.5.33 Site C
Building 3975 is located in the north-central portion of the base and is part of the Water
Treatment Plant. Tank 3965 was reported to be a 550-gallon diesel fuel tank. The tank
passed a leak test hi 1988 and was removed in 1993. Investigations have revealed no COCs.
The site has been recommended to Sacramento County for clean-closure.
3.2.5.34 Site E
Tank 10015 was located in the north-central portion of the base on Alert Road near the
approach end of the Runway 22. It supported the Instrument Landing System Facility at
Building 10015. The tank was reported to be a 1,000-gallon diesel fuel tank. The tank passed
a leak test in 1988 and was removed hi 1993. Investigations have revealed no COCs. The site
has been recommended to Sacramento County for clean-closure.
3.2.5.35 SiteF
Site F is located in the center of the base on Perimeter Road between Runway 22 and the air
traffic control tower. The site consisted of Tank 10065, located west of Building 10065. The
UST was a 1,000-gallon diesel fuel tank. Investigations have revealed no COCs. The UST
was removed hi 1993 and the site has been recommended to Sacramento County for
clean-closure.
3.2.5.36 Site G
Site G is located in the southeast portion of the base near Sites H and 53. The site is south of
Building 18018 and consists of a fiberglass 6,000-gallon diesel fuel tank. Investigations have
revealed no COCs. The UST was removed in 1993 and the site has been recommended to
Sacramento County for clean-closure.
RL/10-95/ES/1260005.AWS
3-12
-------
3.2.5.37 SiteH
Site H is located in the southeast portion of the base near Sites G and 53. It consisted of a
steel 750-gallon diesel fuel tank located at the northeast corner of Building 18020.
Investigations have revealed no COCs. The UST was removed hi 1993 and the site has been
recommended to Sacramento County for clean-closure.
3.2.5.38 Site I
Site I consists of Tank 4853 and is located hi the north-central portion of the base,
approximately 60 feet east of the helicopter washrack. The steel 550-gallon UST reportedly
stored unleaded gasoline. The UST passed a leak test hi 1988 and was removed hi 1993.
Investigations have revealed no COCs. The site has been recommended to Sacramento County
for clean-closure.
RL/10-95/ES/1260005.AWS
3-13
-------
-------
4.0 Soil Operable Unit "Petroleum Only" Sites Selected for No
Action Under CERCLA (but which remain to be closed
under other regulations)
4.1 Declaration for the Soil Operable Unit Petroleum Only Sites Selected for No
Action
No Action is Necessary Based
on the Lack of Statutory Authority under CERCLA
4.1.1 Site Name and Location
Soil OU "Petroleum Only" Sites Selected for No Action Under CERCLA (but which remain to
be closed under other regulations)
Mather AFB (a NPL Site),
Sacramento County, California
4.1.2 Statement of Basis and Purpose
The "petroleum only" sites were investigated under the Mather AFB IRP and are described
and evaluated in previous RI/FS documents. However, there is no CERCLA authority to take
action at these sites. Therefore, they will be cleaned up under RCRA Subtitle I and other
applicable State of California regulations with regulatory oversight by the CVRWQCB, and
Sacramento County as appropriate. The IRP Soil OU "petroleum only" sites for which the no
action remedial alternative was developed at the formerly active Mather AFB include: Site 19
-Fuel Tank Sludge Burial Site, Site 29/B - Fuel Spill at POL Yard Number 4, Site 32 - Fuel
Spill at Army/Air Force Exchange Services Station, Site 34 - Fuel Spill at Family Housing
Army/Air Force Exchange Services Station, Site 35 - Building 3326, and Site 36 -
Building 3286. These sites consist of only petroleum contamination and have not been
remediated, with the exception of Site 32 which was remediated hi late 1995 through soil
excavation and is expected to be closed by the Regional Water Quality Control Board. Section
3.0 of this ROD discusses sites which consist of only petroleum contamination. These sites
have been clean-closed or recommend for clean-closure by Sacramento County. These
decisions are based on the Administrative Record for these sites.
The USEPA Region IX and the State of California concur on the lack of statutory authority
under CERCLA to examine remedial actions for the "petroleum only" sites; therefore, those
RL/10-95/ES/1260005.AWS
-------
sites will be remediated under the Defense Environmental Restoration Program, RCRA
Subtitle I and other applicable State of California regulations.
4.1.3 Description of the Selected Remedy
The COCs at the "petroleum only" sites are exempt from remedial action under CERCLA.
Therefore, a "no action" decision is the selected remedy for the "petroleum only" sites based
on the lack of statutory authority under CERCLA. The "petroleum only" sites include: Sites
19, 29/B, 32, 34, 35, and 36. Based on the human health risk assessment, all cancer risks are
within or below the acceptable range of 1 x 10"* to 1 x 10"6 and all non-cancer risks have a
hazard index of less than 1.0 in their current state.
4.1.4 Declaration Statement
The USEPA does not have authority under CERCLA Section 104 to address the "petroleum
only" sites. The "no action" decision does not constitute a finding that adequate protection has
been achieved at the sites. Cleanup alternatives have been developed and documented in the
FFS Report [IT 1995a] and these sites will be addressed under RCRA Subtitle I and other
applicable State of California regulations, with regulatory oversight by the CVRWQCB, and
Sacramento County as appropriate. Cleanup activities at the "petroleum only" sites are not
subject to the same requirements as the CERCLA sites, i.e., "petroleum only" sites do not
require a CERCLA five-year review, are not subject to the 15 month requirement to begin
remedial activities, etc. However, permits will be required for remedial activities.
4.2 Decision Summary for Soil OU "Petroleum Only" Sites Selected for No
Action Under CERCLA (but which remain to be closed under other
regulations)
4.2.1 Site Name, Location, and Description
Locations of the Soil OU "petroleum only" sites at the formerly active Mather AFB are
presented in Figure 4-1 and include: Site 19 - Fuel Tank Sludge Burial Site, Site 29/B - Fuel
Spill at POL Yard Number 4, Site 32 - Fuel Spill at Army/Air Force Exchange Services
Station, Site 34 - Fuel Spill at Family Housing Army/Air Force Exchange Services Station,
Site 35 - Building 3326, and Site 36 - Building 3286.
RL/10-95/ES/1260005.AWS 4-2
-------
Rgure 4-1. Soil Operable Unit "Petroleum Only" Sites
SOIL OU PETROLEUM ONLY SFTES
3000
6000 FEET
-------
4.2.2 Site History and Enforcement Activities
Cleanup options were developed for the "petroleum only" sites and are presented in the FFS
Report [IT 1995a]; however, the USEPA does not have authority under CERCLA to address
these sites. Therefore, the no action decision is documented as the selected remedy in this
section of the ROD.
Previous investigations have been conducted at the Soil OU "petroleum only" sites as part of
the USAFIRP and are summarized hi Table 4-1.
Table 4-1. Previous Investigations at the Soil Operable Unit "Petroleum Only" Sites
SITE NUMBER
19
29/B
32
34
35
36
APPLICABLE INVESTIGATION
1,2,3,4,5,6,9,10,11
1,6,8,9, 10, 11
1,4,6,7, 10, 11
1, 8, 9, 10, 11
8,9, 10, 11
8,9,10,11
1. Installation Restoration Program (IRP) Records Search for Mather Air Force Base, Phase I [CH2M-Hill,
Inc. 1982];
2. IRP Phase II, Stage 2 Investigation [AeroVironment 1987];
3. Well Redevelopment and Sampling Plan [IT 1988a];
4. Quarterly Routine Groundwater Sampling [IT 1995c] and [EA 1990a-c];
5. Site Inspection Report [IT 1990a];
6. Group 2 Sites Remedial Investigation Report [IT 1992a];
7. Group 3 Sites Technical Memorandum [IT 1993a];
8. Underground Storage Tank Closure Reports [IT 1990b and IT 1993c-d];
9. Soil Operable Unit (OU) and Groundwater OU Additional Field Investigation Report [IT 1994a];
10. Groundwater OU and Soil OU FFS Report [IT 1995a]; and
11. Mather Baseline Risk Assessment Report [IT 1995d].
4.2.3 Highlights of Community Participation
The public participation requirement of CERCLA Sections 113(k)(2)(B)(I-v) and 117 do not
apply to these sites; however, these sites were included hi the Proposed Plan, and the public
comment period (held from May 8 through June 7, 1995) and public meeting (held
May 18, 1995) to address the Proposed Plan and content of supporting RI/FS documents.
RL/10-95/ES/I260005.AWS 4-4
-------
4.2.4 Scope and Role of Response Action
Since there is no CERCLA authority to take action at these sites, this section of the ROD
presents the no action alternative to indicate that no action will occur at these sites under
CERCLA authority as the planned response action.
4.2.5 Summary of Site Characteristics
The Soil OU is comprised of contaminated soils associated with OWSs, gas stations, and other
miscellaneous sites. A summary of hazardous material releases is provided in the following
section along with a summary of nature and extent of contamination on a site-by-site basis.
The sources of contamination are fuels storage and delivery. The objective of this section of
the ROD is to address the primary concerns at the Soil OU "petroleum only" sites posed by
soil contamination.
Environmental studies were initiated by the USAF in 1982 to investigate soil contamination
resulting from past base operations. The USEPA placed Mather AFB on the NPL (or
"Superfund" list) in 1989. In order to organize cleanup efforts, the base is divided into five
OUs. This has allowed sites with similar sources of contamination and site conditions to be
grouped together. This section of the ROD discusses potential cleanup options for one of the
OUs, the Soil OU. Previous RODs presented cleanup options for the AC&W OU [IT 1993e]
(where groundwater contamination is now being extracted and treated by air stripping) and the
Landfill OU, while the Groundwater OU is presented hi Section 5.0 of this ROD. Any
remaining sites will be addressed hi the Final Basewide OU.
Previous PJs have been conducted at the Soil OU "petroleum only" sites as part of the USAF
IRP. A brief description of the nature and extent of contamination at each of the Soil OU
"petroleum only" sites is provided hi the following sections and Table 4-2.
4.2.5.7 Site 19 - Fuel Tank Sludge Burial Site
Site 19 is located hi the northwest portion of the base inside a diked area containing two JP-4
ASTs. It was reported that the site may have continued small quantities of weathered sludge
from fuel tank cleaning operations. Contamination was identified hi the shallow subsurface
soils. The only COC at this site is gasoline. The COC is not related to the marked disposal
site, but apparently is related to the operation of the ASTs, and associated USTs and piping.
RL/10-95/ES/1260005.AWS
4-5
-------
Table 4-2. Estimated Areas and Volumes - Subsurface Soils
Site Number
19
29/B
32*
34
35
36
Contaminant of
Concern
TPH-G
TPH-D
TPH-G
Benzene
TPH-G
TPH-G
TPH-G
TPH-G
Area
(square feet)
5.4 x 104
(a)
1.4 xlO5
8.0 x 104
1.6xl03
1.3 x 10"
6.9 x 103
2.6 x 104
Volume
(cubic feet)
5.4 x 105
(a)
6.3 x 106
4.1xl06
1.7 x 104
3.0 x 105
7.6 x 104
1.2xl06
(a) = diesel detections are sporadic and coincide with higher concentration gasoline detections
TPH-D = Total petroleum hydrocarbons as diesel TPH-G = Total petroleum hydrocarbons as gasoline
*Contaminated soil was excavated in late 1995. Site 32 is expected to be closed by the Regional Water Quality Control Board.
4.2.5.2 S/te 29/B - Fuel Spill at Petroleum Oil and Lubricant Yard Number 4
Site 29 is situated near the western end of the Main Base and was used as a service station and
POL yard from 1958 until 1988. The site consisted of four 25,000-gallon aviation gasoline
USTs which were removed in 1984 and replaced with four fiberglass 20,000-gallon USTs
which were removed in 1994. Site B is located adjacent to Site 29 and consisted of four
25,000-gallon USTs and one empty steel 550-gallon tank used for storing waste fuel. The
USTs were removed in 1993. Contamination was identified in the shallow and deep
subsurface soils. The COCs identified at the site are benzene, diesel, ethylbenzene, and
xylenes. This site is currently being remediated by bio venting with SVE at "hot spots".
4.2.5.3 S/te 32 - Fuel Spill at Army/Air Force Exchange Services Service
Station
Site 32 is located in the north central portion of the base, in the Main Base administration and
operations area. Between 1960 and 1973, a total of five, steel 10,000-gallon USTs were
installed at this site. Three of the USTs and associated piping were removed hi 1988. The
two remaining USTs were removed hi 1994. In addition, a 550-gallon waste oil tank was
removed from the site in 1994. Contamination was identified hi the shallow subsurface soils.
The only COC identified at the site is gasoline. This site has been remediated through
excavation of the soil hi late 1995. It is expected that the site will be closed by the Regional
Water Quality Control Board.
RL/10-95/ES/1260005.AWS
4-6
-------
4.2.5.4 Site 34 - Fuel Spill at Family Housing Army/Air Force Exchange
Services Service Station
Site 34 is located in the south central portion of the base, approximately 1,500 feet northeast
of the south gate and adjacent to the former Family Housing Area. Building 21030 was
constructed in 1968 and operated as an Army/Air Force Exchange Services Service Station
until its closure in February 1988. Three, steel 10,000-gallon USTs located immediately
northeast of Building 21030 were installed in 1968 to store unleaded premium, unleaded
regular, and leaded regular gasoline. Additionally, two 250-gallon waste oil USTs are located
at the southwest corner of the stations property. Contamination was identified in the shallow
subsurface soils. The COCs identified at the site are benzene, gasoline, and xylenes.
4.2.5.5 Site 35 - Building 3226 - Four Abandoned USTs
Site 35 is located in the western portion of the Main Base and is the former location of four
25,000-gallon steel USTs. The USTs stored aviation gasoline from 1945 until approximately
1965. The USTs were removed in 1989. Contamination was identified in the deep subsurface
soils. The only COC identified at the site is gasoline.
4.2.5.6 Site 36 - Building 3286
Site 36 is located in the western portion of the Main Base and is the former location of four
25,000-gallon steel USTs. The USTs stored motor gasoline from 1945 until approximately
1965. The USTs were removed in 1988. Contamination was identified in the shallow and
deep subsurface soils. The only COC identified at the site is gasoline.
4.2.6 Summary of Site Risks
Remedial investigation activities at Mather AFB included fate and transport modeling and a
MBRA [IT 1995d]. The data collected and utilized in the RIs and FFS were of USEPA
quality Level HI, IV, or V, or equivalent [USEPA 1987]. Formal data validation of the
RI- and FFS-generated data was performed to ensure that data were of the quality
commensurate with their intended use.
Based on the human health risk assessment, all cancer risks are within or below the acceptable
range of 1 x lO'4 to 1 x 10"6 and all non-cancer risks have a hazard index of less than 1.0,
respectively.
RL/IO-95/ES/I260005.A.WS 4-7
-------
4.2.6.1 Human Health Risks
Analytes detected in the course of the RI activities at Mather AFB were subjected to a
multi-step screening process to determine COCs. This screening process is presented in
Section 2.2.6.1. The following steps were employed in the COC determination process for the
Soil OU sites and are discussed hi Section 2.2.6.1.
• initial screening methods prescribed by USEPA guidance;
• comparison to background;
• comparison to ARARs;
• comparison to analytical method quantitation limit;
• evaluation of operational history (i.e., process knowledge); and
• evaluation of estimated risk to human and ecological receptors.
4.2.7 Statutory Authority Finding
The no action finding is selected based on the petroleum exclusion in CERCLA.
RL/10-95/ES/I260005.AWS 4-8
-------
5.0 Groundwater Operable Unit Plumes Selected for Remedial
Action
5.1 Declaration for the Groundwater Operable Unit Plumes Selected for Remedial
Action
Statutory Preference for Treatment as a
Principal Element is Met
and a Five-Year Review is Required for
the Main Base/SAC Industrial and Site 7 Groundwater Plumes
Statutory Preference for Treatment as a
Principal Element is Not Met
and a Five-Year Review is Required for
the Northeast Groundwater Plume
5.1.1 Plume Name and Location
Groundwater OU Plumes Selected for Remedial Action
Mather AFB (a NPL Site),
Sacramento County, California
5.1.2 Statement of Basis and Purpose
The Groundwater OU plumes were investigated under the Mather AFB IRP and are described and
evaluated in the RI/FS documents. This decision document presents the selected remedial actions
which were developed for the Groundwater OU plumes at the formerly active Mather AFB.
These plumes include: the Main Base/SAC Industrial Area, the Site 7, and the Northeast. These
remedial actions were chosen in accordance with CERCLA, as amended by SARA, and to the
extent practicable, the NCP. These decisions are based on the Administrative Record for these
plumes.
The USEPA Region IX and the State of California concur on the selected remedial alternatives
for each of the Groundwater OU plumes.
5.1.3 Assessment of the Plume
Contamination exists at the Groundwater OU plumes as a result of past USAF operations
conducted between 1918 and 1993. The Groundwater OU encompasses the contaminated
groundwater beneath and within the immediate vicinity of the base with the exception of the
RL/10-95/ES/1260005.AWS
5-1
-------
AC&W OU plume, which is addressed in a separate ROD (IT, 1993). The main sources of
contamination include industrial activities, equipment maintenance, landfill disposal, other waste
disposal activities (i.e., Site 7), and fuels storage and delivery.
Investigation of numerous IRP sites has identified several sources of groundwater contamination,
most notably Site 57, where chlorinated solvents have been detected in soil and soil gas over a broad
area. Site 18 may also be a source; an SVE pilot test was conducted as part of the Additional Site
Characterization Remedial Investigation (ASC RJ) in 1995 (IT Corp, 1996a). The location of'hot
spots' of contamination at the water table indicates the likelihood of nearby sources of contamination
in the overlying soil or perhaps in the upgradient direction (i.e. the direction from which the
contamination would be carried by the moving groundwater). Examples are near Site 37/39/54 and
near Site 56. These sources must have existed in the past, and many probably still exist today, even
though the use of the chemicals at Mather has been eliminated for years. Additional continuing
sources of groundwater contamination were investigated in 1995 during the ASC RI (IT Corp.,
1996b). Portions of the sanitary sewer system that overlie groundwater contamination at the water
table were targeted for flushing, sampling and soil gas measurements.
Known vadose-zone sources are addressed as part of the Soil OU (this ROD) or will be addressed
in the Final OU ROD. Additional characterization may be necessary to evaluate potentially
significant sources of groundwater contamination. Any remedial actions for additional source
areas will be addressed as part of a future decision document.
Actual or threatened releases of hazardous substances from these plumes, if not addressed by
implementing the response actions selected in this section of the ROD, may present an imminent
and substantial endangerment to public health, welfare, or the environment.
5.1.4 Description of Selected Remedy
This section of the ROD addresses remedies related to contamination of the groundwater
underlying the Main Base/SAC Industrial Area, the Site 7 Area, and the Northeast Area Landfill
Sites. Any contamination of the soil overlying the groundwater plumes has been addressed in
separate sections of this ROD (Sections 2.0 and 4.0).
Based on the human health risk assessment, all cancer risks are within or below the acceptable
range of 1 x 10"4 to 1 x 10"6 and all non-cancer risks have a hazard index of less than 1.0,
respectively, in their current state, except for the Main Base/SAC Industrial Area Groundwater
RL/10-95/ES/1260005.AWS
5-2
-------
Plume which has a cancer risk greater than 1 x 10"4 associated with the highest concentration
detected in the groundwater plume. Therefore, the selected remedies will be instituted to reduce
risk to human health and the environment and to comply with the requirements that are ARARs
based on the beneficial use of the groundwater and the specific conditions of the site.
Table 5-1 provides the major components of the selected remedy for each of the Groundwater OU
plumes.
Table 5-1. Selected Remedial Alternatives for the Groundwater OU Plumes
Selected Remedial Alternative
Main/SAC.2
SP7.2
NE.l
Description
Groundwater extraction, air stripping with off-gas treatment (carbon
adsorption), and groundwater injection*; and groundwater monitoring
Groundwater extraction, air stripping with off-gas treatment (carbon
adsorption), and groundwater injection*; and groundwater monitoring
Long-term groundwater monitoring
* Alternative discharge options may be implemented for discharge of treated groundwater. Examples of alternate
means of discharge are: injection into a deeper aquifer; recharge through the vadose zone; surface water discharge;
provision of water to industrial/agricultural user(s); and provision of water for municipal supply.
SAC = Strategic Air Command NE = Northeast OU = operable unit SP7 = Site 7
5.1.5 Statutory Determinations
The selected remedies satisfy the statutory requirements of Section 121(b) of CERCLA, as
amended by SARA, in that the following four mandates are attained:
• the selected remedies are protective of human health and the environment;
• the selected remedies comply with federal and state requirements that are legally
applicable or relevant and appropriate to the remedial actions;
• the selected remedies are cost-effective; and
• the selected remedies utilize permanent solutions and alternative treatment
technologies, or resource recovery technologies, to the maximum extent
practicable.
These remedies will result in hazardous substances remaining onsite at some of the groundwater
plumes above health-based levels during the remedial action. Therefore, a review will be
conducted within five years after commencement of the remedial actions to ensure that the
RL/10-95/ES/1260005.AWS
-------
remedies continue to provide adequate protection of human health and the environment, and
protect groundwater quality.
5.2 Decision Summary for Groundwater OU Plumes Selected for Remedial Action
5.2.1 Plume Name, Location, and Description
The Groundwater OU plumes selected for remedial action at the formerly active Mather AFB are
presented in Figure 5-1 and include the: Main Base/SAC Industrial Area Groundwater Plume,
the Site 7 Groundwater Plume, and the Northeast Groundwater Plume.
5.2.2 Site History and Enforcement Activities
Previous investigations have been conducted at the Groundwater OU plumes as part of the US AF
IRP and are summarized in Table 5-2.
5.2.3 Highlights of Community Participation
The public participation requirement of CERCLA Sections 113(k)(2)(B)(I-v) and 117 were met
through a public comment period (held May 8 through June 7, 1995) and public meeting (held
May 18, 1995) to address the Proposed Plan and content of supporting RI/FS documents.
Table 5-2. Previous Investigations at the Groundwater Operable Unit Sites
Groundwater Plume
Main Base/Strategic Air Command
Industrial Area
Site 7
Northeast
Applicable Investigation
1,2,3,4,5,6,7,8,9,10,11
1,2,3,4,5,6,7,8,9,10,11
1,2,3,4,5,6,7,8,9,10,11
1. Installation Restoration Program (IRP) Phase II, Stage 1 Investigation [Weston 1986];
2. IRP Phase II, Stage 2 Investigation [AeroVironment 1987];
3. IRP Phase II, Stage 3 Investigation [AeroVironment 1988];
4. Well Redevelopment and Sampling Plan [IT 1988a];
5. Quarterly Routine Groundwater Sampling [IT 1995c] and [EA 1990a-c];
6. Site Inspection Report [IT 1990a];
7. Group 2 Sites Remedial Investigation Report [IT 1992a];
8. Group 3 Sites Technical Memorandum [IT 1993a];
9. Soil Operable Unit (OU) and Groundwater OU Additional Field Investigation Report [IT 1994a];
10. Mather Baseline Risk Assessment Report [IT 1995d]; and
11. Groundwater OU and Soil OU Focused Feasibility Study Report [IT 1995a].
RL/10-95/ES/1260005.AWS
5-4
-------
MAIN BASE/SAC INDUSTRIAL X**"
*~ AREA PLUMES /
NORTHEAST
PLUME
Figure 5-1. Groundwater Operable Unit Plumes
LEGEND
NOTE: (DARK) SOLID LINE INDICATES APPROXIMATE EXTENT
OF GROUNOWATER PLUME
3000
6000 FEET
-------
5.2.4 Scope and Role of Response Action
Environmental studies were initiated by the USAF in 1982 to investigate contamination
resulting from past operations at the base. The USEPA placed Mather AFB on the NPL hi
1989. In order to organize cleanup efforts, the base was divided into five OUs. This has
allowed contaminated sites and plumes with similar sources of contamination and
characteristics to be grouped together. The following sections of the ROD discuss the cleanup
options for one of those OUs, the Groundwater OU. The AC&W OU ROD presented cleanup
options for the AC&W plume [IT 1993e], while Sections 2.0, 3.0, and 4.0 of this ROD
presents the cleanup options for the Soil OU sites, many of which overlay the contaminated
groundwater plumes.
5.2.5 Summary of Site Characteristics
Contamination exists at the Groundwater OU plumes as a result of past USAF operations
conducted from 1918 through 1993. The Groundwater OU plumes encompass the
contaminated groundwater beneath and within the immediate vicinity of the base with the
exception of the AC&W OU plume. The main sources of contamination include industrial
activities, equipment maintenance, fire suppression training, landfill disposal, other disposal
activities (i.e., Site 7), and fuels storage and delivery.
The objective of this section of the ROD is to address the primary contamination concerns at
the Groundwater OU plumes. Previous RIs have been conducted at the Groundwater OU
plumes as part of the USAF IRP. A brief description of each of the Groundwater OU plumes
recommended for remedial action, including nature and extent of contamination (volume
estimates are presented in Table 5-3), is provided in the following sections. Any impact to the
soil overlying these plumes were addressed in separate sections of this ROD (Sections 2.0,
3.0, and 4.0).
5.2.5.1 Main Base/SA C Industrial Area Groundwater Plumes
The SAC Industrial Area Groundwater Plume and the Mam Base Groundwater Plume have
been grouped together for the purpose of remediation based on proximity, common
contaminants, and commingling. The Group 2 Sites RI [IT 1992a] and Group 3 Sites
Technical Memorandum [IT 1993a] identified a widespread chlorinated hydrocarbon plume
underlying the Main Base area (Figure 5-1) which extends off-base to the west. The Mam
Base portion of the plume consists of several commingled plumes at the water table which
have merged together in deeper hydrogeologic units and is characterized by high
concentrations of PCE and lower TCE and carbon tetrachloride concentrations. Additionally,
the Group 2 Sites RI and Group 3 Sites Technical Memorandum identified a dissolved-phase
chlorinated hydrocarbon plume underlying the SAC area (Figure 5-1) extending from the
vicinity of Site 57 off-base to the southwest [IT 1992a and IT 1993a]. The SAC Industrial
area portion of the plume is characterized by high concentrations of TCE and lower PCE and
RU10-95/ES/I260005.AWS
5-6
-------
cis-l,2-dichloroethene (DCE) concentrations. The Main Base/SAC Industrial area plume is
oriented northeast-southwest following the general basewide groundwater flow direction. The
COCs identified are 1,1-DCE, 1,2-dichloroethane, benzene, carbon tetrachloride,
chloromethane, cis-l,2-DCE, diesel, gasoline, lead, TCE, PCE, and xylenes. A cancer risk to
humans has been estimated at 3.7 x 10"3 for exposure to groundwater from the SAC Industrial
Area Plume and 9.3 x 10"4 for exposure to groundwater from the Main Base Plume. The basis
for cleanup is protection of human health and groundwater quality.
Table 5-3. Estimates of Volume - Groundwater
Major
COC
TCE
PCE
CC14
Hydrogeologic
Unit
A
Bu
B
D
Total
A
Bu
B
D
Total
A
Bu
B
D
Total
Groundwater Plume
Main Base"
Volume*
(cubic feet)
1.4x 10s
5.4 x 107
4.8 x 108
5.3 x 106
6.8 x 108
1.1 x 108
9.5 x 107
l.Ox 10"
3.9x 108
1.6 x 109
3.6 x 107
1.9x 107
1.3 x 109(2)
1.2 xlO8
1.5 x 10'
SAC
Industrial"
Volume*
(cubic feet)
2.9 x 108
2.2 x 108
1.3x 109
NA
1.8 x 109
1.2x 108
2.4 x 108
5.5 x 108
NA
9.1 x 108
2.3 x 107
4.4. x 107
NA
NA
6.7 x 107
Northeast(l)
Volume*
(cubic feet)
US
NP
NA
NA
NA
US
NP
9.9 x 106
NA
9.9 x 106
US
NP
4.6 x 106
NA
4.5 x 106
Site?
Volume*
(cubic feet)
6.8 x 107
NP
l.SxlO8
NA
2.2 x 10"
5.1 x 107
NP
7.6 x 107
NA
1.3 x 108
NA
NP
NA
NA
NA
TCE = Trichloroethene COC = contaminant of concern PCE = Tetrachloroethene
SAC = Strategic Air Command CCL, = Carbon Tetrachloride NP = Unit Not Present
US = Unit Unsaturated NA = Not Applicable
(1) Hydrogeologic Unit C - PCE Contamination Volume = 9.6 x 101 cubic feet.
(2) Main Base Plume and SAC Industrial Plume volumes are reported under Main Base Plume.
* Estimates of plume size as of 1993.
** Revised estimates will be provided in the Additional Site Characterization RI Report.
RL/10-95/ES/1260005.AWS
5-7
-------
5.2.5.2 Site 7 Groundwater Plume
The Group 2 Sites RI identified a chlorinated hydrocarbon plume underlying the Site 7 area
(Figure 5-1) and extending off-base to the southwest [IT 1992a]. The plume is characterized
by high concentrations of TCE and lower PCE and cis-l,2-DCE concentrations.
The groundwater COCs identified at the Site 7 Plume are 1,1-DCE, 1,2-dichloroethane,
1,4-dichlorobenzene, benzene, chloromemane, cis-l,2-DCE, diesel, PCE, TCE, and vinyl
chloride. A cancer risk to humans has been estimated at 9.7 x 10"5 from exposure to the
groundwater. Even though the cancer risk is within the acceptable range, active remediation is
proposed because the risk is near the 1 x 10"4 threshold, and the plume extends approximately
one mile off-base in the direction of drinking water wells. The basis for the cleanup is
protection of groundwater quality and human health.
5.2.5.3 Northeast Groundwater Plume
The Group 2 Sites RI identified a chlorinated hydrocarbon plume underlying the Northeast
Landfill area (Figure 5-1) [IT 1992a]. This plume is located in the northeast corner of the
base, underlying Sites 3,4, and 5, and appears to have merged with the Main Base/SAC
Industrial Area Plume (see Section 5.2.5.1).
The groundwater COCs identified at the Northeast Plume area are 1,2-dichloropropane,
carbon tetrachloride, chloromethane, cis-l,2-DCE, and PCE. The primary source of
contamination appears to be from Landfill Site Number 4. The risk assessment, using
conservative assumptions and maximum concentrations, estimated the excess cancer risk for
exposure to the groundwater to be 2.4 xlO~5. The excess cancer risk is within the acceptable
range (i.e., 1 x 10"6 to 1 x 10"4) and there is no current pathway by which contaminants could
endanger human health or the environment. Additionally, contaminant concentrations are
expected to decrease over time.
5.2.6 Summary of Site Risks
Based on the human health risk assessment, all cancer risks are within or below the acceptable
range of 1 x 10"4 to 1 x 10~6 and all non-cancer risks less than a hazard index of 1.0 hi their
current state, except for a localized portion of the Main Base/SAC Industrial Area Plumes.
Therefore, the selected remedy will be instituted to reduce risk to human health and the
environment to comply with the requirements that are ARARs based on the beneficial use of
the groundwater and the site-specific conditions.
Actual or threatened releases of hazardous substances, if not addressed by implementing the
response actions selected in the ROD, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
RL/10-95/ES/1260005.AWS
5-8
-------
5.2.7 Description of Alternatives
Two or three remedial alternatives (including the no action alternative) were developed for
each of the three Groundwater OU plumes for detailed analysis in the FFS Report [IT 1995a].
Groundwater is the affected medium; any contamination in the soil overlying the groundwater
plumes has been addressed as part of the Soil OU sections of this ROD (Sections 2.0, 3.0,
and 4.0). Under the no action alternative, groundwater monitoring would continue under the
existing basewide monitoring program.
5.2.7.1 Main Base/SAC Industrial Area Groundwater Plume Remedial
Alternatives
Table 5-4 presents three remedial alternatives developed for application at the Main Base/SAC
Industrial Area Groundwater Plume.
Table 5-4. Main Base/SAC Industrial Plume Remedial Alternatives
ALTERNATIVE
Main/SAC.l
Main/SAC.2
Main/SAC.3
DESCRIPTION
No Action (includes groundwater monitoring)
Extraction of the contaminated groundwater with treatment by air stripping and
injection of the treated groundwater into the aquifer (alternative means of discharge of
treated groundwater may be implemented), and groundwater monitoring. In addition,
carbon will be utilized to adsorb and treat the off-gas from the air stripper, if
appropriate.
Extraction of the contaminated groundwater with treatment by ultraviolet oxidation
and injection of the treated groundwater into the aquifer (alternative means of
discharge of treated groundwater may be implemented), and groundwater monitoring.
SAC = Strategic Air Command
5.2.7.2 Site 7 Groundwater Plume Remedial Alternatives
Table 5-5 presents three remedial alternatives developed for application at the Site "7
Groundwater Plume.
RL/10-95/ES/1260005.AWS
5-9
-------
Table 5-5. Site 7 Plume Remedial Alternatives
ALTERNATIVE
SP7.1
SP7.2
SP7.3
DESCRIPTION
No Action (includes groundwater monitoring)
Extraction of the contaminated groundwater with treatment by air stripping and
injection of the treated groundwater into the aquifer (alternative means of discharge
of treated groundwater may be implemented), and groundwater monitoring. In
addition, carbon and will be utilized to adsorb and treat the off-gas from the air
stripper, if appropriate.
Extraction of the contaminated groundwater with treatment by ultraviolet oxidation
and injection of the treated groundwater into the aquifer (alternative means of
discharge of treated groundwater may be implemented), and groundwater
monitoring.
SP = Site 7
5.2.7.3 Northeast Groundwater Plume Remedial Alternatives
Table 5-6 presents two remedial alternatives developed for application at the Northeast
Groundwater Plume. (See Section 5.2.9.3 for discussion of the selected alternative).
Table 5-6. Northeast Plume Remedial Alternatives
ALTERNATIVE
NE.l
NE.2
Selected Alternative
DESCRIPTION
No Action (includes groundwater monitoring)
Extraction of the contaminated groundwater with treatment by air stripping and
injection of the treated groundwater into the aquifer (alternative means of
discharge of treated groundwater may be implemented), and groundwater
monitoring.
Long term groundwater monitoring and land use restrictions.
NE = Northeast
5.2.8 Summary of Comparison Analysis of Alternatives
The remedial alternatives developed in the FFS Report [IT 1995a] were analyzed in detail using
the nine evaluation criteria required by the NCP (Section 300.430(e)(7)). These criteria are
classified as threshold, primary balancing, and modifying criteria. In order for a remedial
alternative to be selected, it must at a minimum, meet the threshold criteria.
RL/10-95/ES/1260005.AWS
5-10
-------
Threshold criteria are:
overall protection of human health and the environment; and
compliance with ARARs.
Primary balancing criteria are:
long-term effectiveness and permanence;
reduction of toxicity, mobility, or volume through treatment;
short-term effectiveness;
implementability; and
cost.
Modifying criteria are:
• state/support agency acceptance; and
• community acceptance.
The relative ability of each alternative to meet each of the nine criteria were weighed to
identify the alternative providing the best tradeoffs for each site. The following sections
summarize the nine criteria. Table 5-7 presents the results of the comparative analysis.
Table 5-7. Comparative Analysis of Groundwater Remedial Alternatives
Evaluation
Criteria
Plume
Alternative
Overall Protection of
Human Health and the
Environment
Compliance with ARARs
Long-Term Effectiveness
and Permanence
Reduction of Toxicity,
Mobility, and Volume
Short-Term Effectiveness
Implementability
Present Worth Cost
($ millions)
Main Base/SAC Industrial Groundwater Plume
Main/SAC.l
No
NA**
P
P
F
G
7.72
Main/SAC.2"
Yes
Yes
B
B
G
B
20.31
Main/SAC.3
Yes
Yes
B
B
B
B
22.77
Site 7 Groundwater Plume
SP7.1
No
NA**
G
P
G
G
1.12
SP7.2"
Yes
Yes
B
B
G
B
3.21
SP7.3
Yes
Yes
B
B
B
B
5.35
Northeast
Groundwater
Plume
NE.T
No
NA**
G
.P
G
G
0.28
NE.2
Yes
Yes
B
B
G
B
1.91
The State of California and the community concur on the selected remedial alternative* for each of the Groundwater Operable Unit plumes.
** ARARs do not have to be met unless a remedial action is taken.
P = Poor F = Fair G = Good B = Best SP7 = Site 7 NA = not applicable
SAC = Strategic Air Command NE = Northeast ARAR = applicable or relevant and appropriate requirements
RL/10-95/ES/1260005.AWS
5-11
-------
5.2.8.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether or not a cleanup
option provides adequate protection, and it describes how risks, posed through each exposure
route, are eliminated, reduced, or controlled through treatment, engineering controls, or
institutional controls.
5.2.8.2 Compliance with ARARs
Addresses whether a cleanup option will meet all ARARs or federal and state environmental
statutes and/or provide grounds for invoking a waiver. Applicable or relevant and appropriate
requirements include cleanup and protection of groundwater quality for its beneficial use.
Details of the ARARs analysis are described in Section 6.0 of this ROD.
5.2.8.3 Long- Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a cleanup option to maintain
reliable protection of human health and the environment over time, once cleanup goals have
been met.
5.2.8.4 Reduction of Toxicity, Mobility, or Volume
Reduction of toxicity, mobility, or volume refers to the preference for a cleanup option that
uses treatment to reduce health hazards, contaminant migration, or quantity of contaminants at
the site.
5.2.8.5 Short-Term Effectiveness
Short-term effectiveness refers to the period of time in which the remedy achieves protection,
as well as the remedy's potential to create adverse impacts on human health and the
environment that may result during the construction and implementation period until the
cleanup goals are achieved.
5.2.8.6 Implementability
Implementability refers to the technical and administrative feasibility of a remedy, including
the availability of materials and services needed to carry out a particular remedy. It also
includes coordination of federal, state, and local governments in cleanup of the site.
RL/10-95/ES/1260005.AWS
5-12
-------
5.2.8.7 Cost
This criterion examines the estimated cost for each remedial alternative. For comparison,
capital and annual operation and maintenance costs were used to calculate a present worth cost
for each alternative. The present worth cost estimates assume zero equipment salvage value,
zero percent inflation, and a five percent discount factor. A detailed cost analysis was
performed for each of the alternatives proposed in the FFS Report [IT 1995a].
5.2.8.8 State/Support Agency Acceptance
This indicates whether, based on its review of the RI Report [IT 1992a], FFS Report
[IT 1995a], and Proposed Plan [IT 1995b], the state concurs with the preferred cleanup
options. The USAF, as the lead agency, has involved the USEPA and State of California.
5.2.8.9 Community Acceptance
This is an assessment of the general public response following review of the public comments
received on the RI Reports, FFS Report, and Proposed Plan during the public comment period
(held May 8 through June 7, 1995) and public meeting (held May 18, 1995). Section 7.0 of
this ROD contains comments received during the public comment period and responses to
these comments.
5.2.9 The Selected Remedies
This section presents the remedies selected by the USAF, with concurrence by the USEPA and
the State of California for each of the Groundwater OU plumes. The selected remedies were
chosen based on the results of the comparative analysis of the alternatives presented in Table
5-7 and provide the best of trade-offs with respect to the nine evaluation criteria. All design
and construction of the selected remedial actions will be conducted by certified professionals
or under the supervision of certified professionals, as appropriate.
5.2.9.1 Main Base/SAC Industrial Area Groundwater Plume
Alternative Main/SAC.2 was selected by the USAF, with concurrence by the USEPA and the
State of California as the remedy for the Main/SAC Industrial Area Groundwater Plume. The
major components of this remedy include:
• a phased implementation program;
• groundwater extraction, to achieve aquifer cleanup standards, estimated but not
limited to a total rate of 1,300 gallons per minute (gpm);
RL/10-95/ES/1260005. AWS
5-13
-------
• treatment of the extracted groundwater through air stripping with off-gas
treatment (i.e., carbon adsorption) to achieve aquifer cleanup standards MCLs
(see Table 5-8), and to achieve discharge standards;
• groundwater injection per standards in Table 6-7; in combination with other
discharge options that are (a) consistent with attainment of cleanup standards,
and (b) cost-effective.
• land-use restrictions will be implemented on USAF property as appropriate, in
order to preclude installation of groundwater wells that would not be compatible
with protection of public health and the environment; and
• monitoring the groundwater.
Alternative discharge options will be evaluated during remedial design. The design will
incorporate reinjection of treated groundwater and other discharge options that are (a)
consistent with attainment of cleanup standards, and (b) cost-effective. The design will include
contingency planning to avoid or minimize disruption of treatment operations should the
primary discharge options be compromised (i.e. if reinjection capacity declines). Any means
of discharge must meet substantive requirements of ARARs if onsite or be permitted as
required offsite, and would be preceded by public notice and solicitation of public comment as
appropriate. Examples of alternative means of discharge are:
• injection to a deeper aquifer;
• recharge through the vadose zone;
• irrigation;
• surface water discharge;
• provision of water to industrial/agricultural user(s); and
• provision of water for municipal supply.
Capital cost estimates for this remedy are projected at approximately $5.88 million and
operation and maintenance costs are estimated at $62.72 million. Total cost, represented as a
net present worth using a five percent discount rate, is calculated at $20.31 million.
The Main Base/SAC Industrial Area Groundwater Plume cleanup levels are presented in Table
5-8.
RL/10-95/ES/1260005.AWS
5-14
-------
Table 5-8. Main Base/SAC Industrial Area Plume Cleanup Levels
Contaminant of Concern
1,2-DCA
cis-l,2-DCE
Benzene
CC14
Xylenes
1,1-DCE
Chloromethane
TCE
PCE
TPH as Gasoline
TPH as Diesel
Lead
Cleanup Level (mg/L)
5.0 x 10*
6.0 x 10-3
l.OxlO'3
5.0 x 10"4
1.7xlO-2
6.0 x 10'3
3.0 x 10-3
5.0 x ID'3
5.0 x 10°
5.0 x 10-2
1.0x10-'
l.SxlO'2
PRG Basis
CA MCL, PQL
CAMCL
CAMCL
CA MCL, PQL
T&O
CAMCL
SNARL
FMCL
FMCL
PQL
USEPA HA
FMCL
DCA = dichloroethane CC14 = carbon tetrachloride
TCE = trichloroethene PCE = tetrachloroethene
mg/L = milligrams per liter SAC = Strategic Air Command
CA MCL = California Maximum Contaminant Level
DCE = dichloroethene
TPH = total petroleum hydrocarbon
T&O = taste and odor
PQL = Practical Quantitation Limit
SNARL = suggested no adverse response level FMCL = Federal Maximum Contaminant Level
USEPA HA = United States Environmental Protection Agency health advisory
5.2.9.2 Site 7 Groundwater Plume
Alternative SP7.2 was selected by the USAF, with concurrence by the USEPA and the State of
California as the remedy for the Site 7 Groundwater Plume. The major components of this
remedy include:
• ground water extraction at a rate of approximately 250 gpm;
• treatment of the extracted groundwater through air stripping with off-gas
treatment (i.e., carbon adsorption) to achieve aquifer cleanup standards (see
Table 5-9), and to achieve discharge standards;
• groundwater injection per standards in Table 6-7; in combination with other
discharge options that are (a) consistent with attainment of cleanup standards,
and (b) cost-effective;
• land-use restrictions will be implemented on USAF property as appropriate, in
order to preclude installation of groundwater wells that would not be compatible
with protection of public health and the environment; and
• monitoring the groundwater.
RL/10-95/ES/1260005.AWS
5-15
-------
Alternative discharge options will be evaluated during remedial design. The design will
incorporate reinjection of treated groundwater and other discharge options that are (a)
consistent with attainment of cleanup standards, and (b) cost-effective. The design will include
contingency planning to avoid or minimize disruption of treatment operations should the
primary discharge options be compromised (i.e. if reinjection capacity declines). Any means
of discharge must meet substantive requirements of ARARs if onsite or be permitted as
required offsite, and would be preceded by public notice and solicitation of public comment as
appropriate. Examples of alternative means of discharge are:
injection to a deeper aquifer;
recharge through the vadose zone;
surface water discharge;
irrigation;
provision of water to industrial/agricultural user(s); and
provision of water for municipal supply.
Capital cost estimates for this remedy are projected at approximately $738,309 and operation
and maintenance costs are estimated at $3.8 million. Total cost, represented as a net present
worth using a five percent discount rate, is calculated at $3.2 million.
The Site 7 Groundwater Plume cleanup levels are presented in Table 5-9.
Table 5-9. Site 7 Plume Cleanup Levels
Contaminant of Concern
1,1-DCE
1,2-DCA
cis-l,2-DCE
Benzene
1,4-DCB
Chloromethane
Vinyl Chloride
TCE
PCE
TPH as Diesel
Cleanup Level (mg/L)
6.0 x lO'3
5.0 x 10-"
6.0 x 10-3
l.OxlO-3
5.0 x 10-3
3.0 x 10-3
5.0 x 10-4
5.0 x lO'3
5.0 x lO'3
1.0x10-'
PRG Basis
CAMCL
CA MCL, PQL
CAMCL
CAMCL
CAMCL
SNARL
CA MCL, PQL
FMCL
FMCL
USEPA HA
TPH = total petroleum hydrocarbon
DCE = dichloroethene
mg/L = milligrams per liter
PCE = tetrachloroethene
CA MCL = California Maximum Contaminant Level
SNARL = suggested no adverse response level
DCA = dichloroethane
DCB = dichlorobenzene
TCE = trichloroethene
PQL = Practical Quantitation Limit
FMCL = Federal Maximum Contaminant Level
USEPA HA = United States Environmental Protection Agency health advisory
RL/10-95/ES/1260005.AWS
5-16
-------
5.2.9.3 Northeast Groundwater Plume
The USAF, with concurrence by the USEPA and the State of California, has decided that
active remediation of the Northeast Groundwater Plume is not warranted at this time because
action is being taken to remediate the source (Landfill Site 4), and because removing the
low-concentration contaminants from the groundwater would provide little benefit while
incurring high costs. However, because several of the contaminants are above the primary
drinking water standards, institutional controls (such as deed restrictions) will be applied to
prohibit the installation of groundwater supply wells on Mather AFB that would jeopardize
public health or the environment from the Northeast Groundwater Plume area. If off-base
groundwater wells are proposed or constructed that could result in exposure to contaminated
groundwater from the Northeast Plume, the need for active cleanup or other action will be
revisited. Additionally, long-term groundwater monitoring will be continued and modified as
necessary to monitor contaminant concentrations. Monitoring will be conducted pursuant to
Title 23, CCR, Section 2550.10 (Corrective Action Monitoring) for at least one year from the
date that the levels in Table 5-10 are attained. After that time, monitoring will, as required by
the Landfill ROD, be conducted pursuant to Title 23, CCR, Section 2550.8 (Detection
Monitoring), in order to detect potential future releases from Landfill Site 4. Contaminant
concentration levels in the groundwater will be re-evaluated annually. If the contamination
concentrations drop below the levels in Table 5-10 for one year, any institutional controls may
be removed. Prior to the first CERCLA five-year review, additional predictive modeling will
be conducted in order to assess whether the contaminants will meet the levels in Table 5-10
within a reasonable time. The results of that modeling will be published in an appropriate
document or an Explanation of Significant Difference (BSD), if necessary. If, at any time
monitoring or modeling indicates that the contaminants will not meet the levels in Table 5-10
within a reasonable time, or at least forty years from the date of this ROD, or that significant
migration of the contaminants may occur at levels above those in Table 5-10 which impacts
public health or the environment, active remediation will be reconsidered.
No capital costs are associated with this remedy, operation and maintenance costs for
long-term monitoring are estimated at $322,399. Total cost, represented as a net present
worth using a five percent discount rate, is calculated at $279,159.
The Northeast Groundwater Plume cleanup levels are presented in Table 5-10.
RL/10-95/ES/1260005.AWS
5-17
-------
Table 5-10. Northeast Plume Cleanup Levels
Contaminant of Concern
cis-l,2-DCE
CC14
Chloromethane
1 ,2-dichloropropane
PCE
Cleanup Level (mg/L)
6.0 x 10-3
5.0 x 10"
3.0 x lO'3
5.0 x 10'3
5.0 x lO'3
PRG Basis
CAMCL
CA MCL, PQL
SNARL
FMCL
FMCL
DCE = dichloroethene PCE = tetrachloroethene
CC14 = carbon tetrachloride mg/L = milligrams per liter
CA MCL = California Maximum Contaminant Level PQL = Practical Quantitation Limit
SNARL = suggested no adverse response level FMCL = Federal Maximum Contaminant Level
5.2.10 Description of the Selected Remedies
This section is a description of the conceptual engineering features and operation of the
selected remedy for the Main Base/SAC Industrial Groundwater Plume and the Site 7
Groundwater Plume. The specific design details will be determined during the remedial
design phase, and hence, may differ slightly from those indicated and discussed below.
5.2.10.1 Extraction Wells
The contaminated groundwater would be pumped from the zone of interest from production
wells using down-hole submersible pumps. These wells would have a combined production
rate of approximately 1,300 gpm (Main Base/SAC Industrial Plume) and 250 gpm (Site 7
Plume). The influent water would flow through buried poly vinyl chloride (PVC) piping to a
pre-treatment filtration unit.
5.2.10.2 Pre-Treatment Unit
The pre-treatment unit would consist of a bag-type filter. The filter bag would be capable of
removing particles from the influent water that are as small as one micron. Actual
specifications for the pre-treatment unit will be developed during the remedial design phase.
After passing through the pre-treatment unit, the influent would be pumped to the top of the
air stripping tower. A description of the major components of the air stripping treatment unit
is presented below.
RL/10-95/ES/1260005.AWS 5-18
-------
5.2.10.3 Air Stripping Tower and Blower
The ah" stripping tower would be of a cylindrical, vertical design which will allow air flow
countercurrent to the liquid flow through packing. Components of a typical ah" stripping tower
include:
Spray Nozzle - Spray nozzles are used to uniformly distribute the liquid influent
over the packing to avoid channeling and dry spots.
Mist Eliminator - The mist eliminator is a relatively thin bed of packing or
wire mesh material. It is situated above the main packing and spray nozzles and
is used to remove entrained water droplets from the exiting air stream.
Packing System - Within the column of polypropylene packing material, the
liquid and countercurrent air contact each other, stripping contaminants from
the liquid. Over time, the packing material can become encrusted with solids
suspended in the liquid influent or can be fouled with biological growth,
necessitating removal and disposal. This fouling would cause gradual reduced
efficiency in the removal of contaminants, as well as increasing the pressure
drop through the packing resulting in decreased air flow from the blower. It is
anticipated that the removal and refill of the packing material would need to be
carried out only once per year. The used packing would be classified as
non-hazardous waste and could be disposed in a sanitary landfill. The treated
water would exit the tower and be forced by an effluent pump along the effluent
line to the post-treatment infiltration unit.
Blower - The supply air for the air stripping tower is provided by the blower.
After contacting the liquid, the air flows out the top of the stripping tower.
Here the off-gas is warmed by a heater. The heater is used to reduce the
relative humidity in the air stream which increases the effectiveness of the vapor
phase carbon adsorption process and reduces carbon consumption
5.2.10.4 Post-Treatment Unit
Specifications of post-treatment unit (PTU), if needed, will be developed during the remedial
design phase. Purposes of the PTU will be to remove any particulates which may have formed
in the treatment process, and to maintain effluent chemical properties to mitigate potential
chemical, physical, or biological fouling of the aquifer and injection wells. The effluent will
be pumped from the PTU to the injection wells through buried PVC pipelines.
RL/10-95/ES/1260005.AWS
5-19
-------
5.2.10.5 Vapor Phase Carbon Adsorption System
Vapor phase carbon adsorption is included as part of the selected remedy to maintain capture
efficiency of the contaminants present in the off-gas. There are two main types of vapor phase
carbon adsorption systems which may be used in conjunction with the air stripper to remove
contaminants from the off-gas stream. The first type consists of self-contained, portable
activated carbon canisters. These canisters are filled with regenerated granular carbon which
remove impurities from the stripper off-gas and are typically designed for installation on a
concrete pad. The only installation needed is to connect the inlet from the stripper tower
outlet port. The canisters can be connected in a series lead-lag configuration for increased
contact times, or parallel configuration for high flowrates. The useful life of the carbon is
dependent upon the concentration of the organic compounds in the gas stream, flowrate, and
temperature. When the carbon becomes saturated with contaminants, the canister would be
detached, sealed, and shipped for regeneration. The carbon vendor would provide shipping
and regeneration as a service.
The second type of carbon system is a permanent skid-mounted structure in which single or
dual beds of granular activated carbon are arranged. The system employs the same principles
as the carbon canisters, however, maintenance is more involved, but because of the size
difference in the carbon canister versus carbon bed, maintenance is nowhere near as frequent.
Maintenance consists of removal and transport of the spent carbon to a regeneration facility,
cleaning the vessel and filling the vessel with regenerated carbon. The shipping and
regeneration service would be provided by the carbon vendor.
After carbon treatment, the treated vapor would be discharged to the atmosphere. The off-gas
would be analyzed continuously to monitor the level of releases of organic gases to the
atmosphere.
Selection of the type of carbon system will be made after further analysis in the design phase.
5.2.10.6 Discharge of Treated Water
Detailed specifications for the injection wells, including location and selection of well screen
intervals, will be developed during the remedial design phase. Treated effluent will be
injected into the formation using wells screened in the hydrogeologic unit of interest. Based
on experience at the AC&W Site, it was found that a 2:1 ratio of injection to extraction wells
is necessary for optimization of the system.
RL/10-95/ES/1260005.AWS
5-20
-------
Alternative discharge options will be evaluated during remedial design. The design will
incorporate reinjection of treated groundwater and evaluate reinjection in conjunction with
other discharge options that are (a) consistent with attainment of cleanup standards, and (b)
cost-effective. The design will include contingency planning to avoid or minimize disruption
of treatment operations should the primary discharge options be compromised (i.e. if
reinjection capacity declines). Any means of discharge must meet substantive requirements of
ARARs if onsite or be permitted as required offsite, and would be preceded by public notice
and solicitation of public comment as appropriate. Examples of alternative means of discharge
are:
• injection to a deeper aquifer;
• recharge through the vadose zone using injection wells, infiltration ponds, or
infiltration galleries;
• surface water discharge (i.e., storm water drainage);
• provisions of water to industrial/agricultural users;
• provisions of water for municipal supply; and
• irrigation (golf course, parks, wetlands).
All disposal alternatives will comply with discharge permit requirements, and will be
documented in an BSD, if appropriate.
The selected remedy (1) prohibits the bypass or overflow of untreated or partially treated
waste; (2) limits discharge to injection of treated water unless (a) additional or alternative
discharge is done under applicable permit or (b) additional or alternative discharge meets the
substantive requirements of applicable or relevant and appropriate regulations as agreed by the
FFA parties; (3) requires that the pH of any treated water shall be between 6.5 and 8.5 or
equivalent to the receiving waters.
Initial background concentration of all potential pollutants shall be determined for each water-
bearing zone in which reinjection will occur. These constituents will be monitored during RA
until it can be determined that there is no condition of pollution occurring as a result of the
discharge. If the results necessitate the establishment of reinjection standards for additional
constituents in order to meet ARARs, an amendment to the ROD or other appropriate decision
procedure will be considered by the U.S. Air Force, U.S. EPA, and Cal EPA.
The selected remedy does not contemplate on-site disposal of hazardous wastes or wastes
derived from the remedial action. Therefore no action-specific ARARs were selected. If
RL/IO-95/US/12WXXI5. A WS
5-21
-------
hazardous or other wastes are derived from the remedial action, such as waste water,
screenings, sludges and other solids generated during construction, operation and maintenance
of the treatment system, these will be disposed of off-site in accordance with applicable
federal, state, and local laws, regulations, and ordinances. However, these requirements
would not be considered ARARs under CERCLA, as ARARs apply only to on-site activities.
5.2.10.7 Affected Water Supply Wells
The Main Base/SAC Industrial Area Groundwater Plume has reached at least one water supply
well beyond the base boundary and potentially could reach other wells beyond the base
boundary. The current levels of contaminant constituents in the affected well are below the
maximum contaminant level (MCL) safe drinking water standards promulgated by USEPA and
the Slate hut arc near the one-in-a-million cancer risk level.
To address the human health threat posed by the Plume to affected water supply wells and wells
that may be affected in the future due to plume migration, and to address plume migration as a
result of supply wells, the USAF will develop a Mather-specific off-base Water Supply
Contingency Plan in consultation with the State, USEPA, and local water agencies. The
proposed Water Supply Contingency Plan will be subject to public review and comment. The
USAF will submit a Draft Water Supply Contingency Plan by June 27, 1996, to the agencies and
the local water agencies for review and comment. The USAFs commitment to submit a draft
Contingency Plan to the other ROD signatory parties is a schedule deadline enforceable under
the Mather AFB Federal Facility Agreement (FFA).
The proposed plan will address the following for each affected well or potentially affected well:
(1) Determine which wells will likely be affected;
(2) Provide an ongoing monitoring plan of supply wells and their guard wells, including
increased frequency of sampling once a constituent from the Plume has been detected;
(3) Determine the impact of supply well pumping on the plume and recommend action(s) to
minimize plume migration;
RL/10-95/ES/I260005.AWS
5-22
-------
(4) Evaluate the short term and long term options for providing alternate water supplies (the
evaluation shall consider the technical effectiveness in dealing with the health threat,
implementation time frame, cost, and acceptability to the water purveyor);
(5) Propose a preferred alternative, including an implementation time schedule, which should
address the sequencing of alternate remedies if the final solution is to include short-term
and long-term solutions);
(6) Develop a trigger for ascertaining when an option(s) should be implemented;
(7) Propose measures and an implementation schedule to mitigate the vertical migration of
contaminants to deeper aquifer zones for each well likely to be impacted by the plume;
and
(8) Determine when the monitoring plan can be terminated.
USAF development of the off-base Water Supply Contingency Plan shall be subject to the
consultation provisions and requirements of Section 7 of the Mather AFB FFA, effective 21 July
1989, among USEPA, the State, and the USAF. For purposes of Section 7 of the Mather AFB
FFA, the Contingency Plan shall be considered a primary document.
The State reserves any rights it would otherwise have, absent this ROD or the Mather FFA, with
respect to the impact of the plume on any affected well or other likely affected wells. This
reservation of rights expires upon concurrence with the final contingency plan. The Air Force
intends, aside from this ROD and within any necessary constraints of the Federal Tort Claims
Act, to work with affected parties, Sacramento County, and the State regarding immediate needs
to abate impacts of the plume. Nothing stated in this ROD shall be construed as an admission by
the Air Force of tort liability.
5.2.11 Performance Evaluations
The Air Force will develop monitoring, reporting, and notification programs during the RD/RA
phase. The monitoring program shall include sufficient monitoring (both in terms of location,
frequency, and test methods) to evaluate the effectiveness of the RA and ensure that discharge
standards for effluent reinjection or other approved discharge are being met.
RL/10-95/ES/I260005.AWS
5-23
-------
Periodic performance evaluation reports will present groundwater monitoring data. The
evaluation reports shall demonstrate that the capture zones of the extraction wells are consistent
with attainment of the aquifer cleanup standards, and that the injection of treated groundwater
does not degrade the receiving water quality.
In addition to operational monitoring of influent and air emissions, routine sampling of the
groundwater will be conducted to monitor the migration of the contaminated plumes and
decreases in the concentrations. Specific sampling, analysis, and monitoring requirements will
be established during the remedial design. This data will be utilized to evaluate the need for
institutional control as well as to periodically evaluate the performance of the remedial system.
Five-Year Site Reviews and periodic performance evaluations, as recommended by USEPA,
are to be included as a component of the selected remedy. The specific schedule for periodic
performance evaluations will be determined during the remedial design phase. However,
USEPA recommends an initial evaluation to be conducted one to two years after the remedy is
operational and functional, in order to determine whether modifications to the restoration
action are necessary. The USEPA also recommends that more extensive performance
evaluations be conducted at least every five years [55 Federal Register (FR) 8740]. The
purpose of the evaluations is to determine whether cleanup levels have been, or will be,
achieved in the desired time frame. After the evaluations are completed, the following options
should be considered:
• discontinue operations;
• upgrade or replace the remedial action to achieve the original remedial action
objectives or modified remedial action objectives; and/or
• modify the remedial action objectives and continue remediation, if appropriate
[55 FR 8740].
5.2.12 Statutory Determinations
The selected remedies satisfy the statutory requirements in CERCLA Section 121(b), as
amended by SARA, in that the following mandates are attained:
• the selected remedies are protective of human health and the environment, will
decrease site risks, and will not create short-term risks nor have cross-media
consequences;
RL/10-95/ES/1260005.AWS
5-24
-------
• the selected remedies comply with federal and state requirements that are
applicable, or relevant and appropriate, to the remedial actions;
• the selected remedies are cost-effective in their fulfillment of the nine CERCLA
evaluation criteria; and
• the selected remedies utilize permanent solutions to the maximum extent
practicable.
RL/10-95/ES/1260005.AWS
5-25
-------
-------
6.0 List of Applicable or Relevant and Appropriate
Requirements and To-Be-Considereds
Pursuant to Section 121(d)(l) of CERCLA, remedial actions must attain a degree of cleanup
which assures protection of human health and the environment. Additionally, remedial actions
that leave hazardous substances, pollutants, or contaminants onsite must meet standards,
requirements, limitations, or criteria that are ARARs. Federal ARARs include requirements
under any federal environmental laws, while state ARARs include promulgated requirements
under state environmental or facility-siting laws that are more stringent than federal ARARs,
and that have been identified to USEPA by the State of California in a timely manner.
Applicable requirements are those cleanup standards, control standards, and other substantive
environmental protection requirements, criteria, or limitations promulgated under federal or
state law that specifically address a hazardous substance, pollutant, contaminant, remedial
action, location, or other circumstance at a CERCLA site. In general, onsite actions need
comply only with the substantive aspects of ARARs, not with corresponding administrative
requirements (such as, but not limited to, permits, recordkeeping, and reporting).
Relevant and appropriate requirements include those that, while not "applicable" to a
hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance
at a CERCLA site, nevertheless address problems or situations sufficiently similar to those
encountered at the CERCLA site to indicate their use is well-suited to the particular site. A
requirement must be either applicable or both relevant and appropriate to be an ARAR. If no
ARAR addresses a particular situation, or if an ARAR is insufficient to protect human health
or the environment, then nonpromulgated standards, criteria, guidance, and TBC advisories
may be used to develop a protective remedy.
Applicable or relevant and appropriate requirements are identified on a site-specific basis from
information about site-specific chemicals, specific actions that are being considered as
remedies, and specific features of the site location. There are three categories of ARARs:
• Chemical-specific ARARs are numerical values or methodologies which, when
applied to site-specific conditions, result in the establishment of numerical
values. They are used to determine acceptable concentrations of specific
hazardous substances, pollutants, and contaminants in the environment;
RL/IO-95/ES/1260005.AWS
6-1
-------
• Location-specific ARARs are restrictions placed on the concentration of hazardous
substances or the conduct of activities solely because the site occurs in, or may
affect, a special location, such as a wetland or floodplain; and
• Action-specific ARARs are technology- or activity-based requirements or
limitations on actions taken with respect to hazardous waste.
The ARARs and TBCs were developed using the following guidelines and documents: CERCLA
Compliance with Other Laws Manual, Part I: Interim Final [USEPA 1988]; "CERCLA
Compliance with Other Laws Manual, Part II: Clean Water Act and Other Environmental
Statutes and State Requirements" [USEPA 1989b]; and "California State Water Resources
Control Board ARARs Under CERCLA" [SWRCB 1992]. The following sections outline the
ARARs and other information considered for the Soil OU sites where remedial actions will be
initiated (listed in Section 2.0 of this ROD) and Groundwater OU plumes (listed in Section 5.0 of
(his ROD).
The following sections present the federal and state regulations and guidance under each
appropriate ARAR category (i.e. chemical-, location-, and action-specific). Chemical-specific
ARARs and TBCs are listed in Section 6.1, location-specific ARARs and TBCs are listed in
Section 6.2, and action-specific ARARs and TBCs are listed in Section 6.3.
6. 7 Chemical-Specific ARARs and TBCs
Chemicals of concern for the Soil OU sites and Groundwater OU plumes are listed in the
following sections. These COCs were identified for soils (i.e., sediments, surface soils, and
subsurface soils), surface water, and groundwater. The chemical-specific ARARs and TBCs for
these COCs are presented based on whether they are ARARs or TBCs, the type of
contamination, and applicable media.
6.1.1 Federal Chemical-Specific ARARs and TBCs
The following federal chemical-specific ARARs and TBCs have been identified for the Soil OU
sites and Groundwater OU plumes.
6.1.1.1 Soils
The only federal ARAR is USEPA Toxic Substance Control Act (TSCA), implemented through
40 Code of Federal Regulations (CFR) Part 761.120-135, which applies to sites where the soil
contains greater than 50 mg/kg total PCB and the spill occurred after February 17, 1978. The
TSCA is a TBC for the Site 15 contaminated sediments, because PCB concentrations do not
RUIO-95/ES/I26U005.AWS
6-2
-------
not exceed 50 mg/kg. The date(s) the PCBs were released to the soils at Mather AFB is not
known, so these requirements are considered relevant and appropriate for establishing
chemical-specific COC limits. 40 CFR Part 761 is also identified in Section 6.3.1.1 as a
chemical-specific TBC for Site 15 soils.
6.1.1.2 Surface Waters
Sites 13, 15, and 69 have identified surface waters at which the following TBCs would apply.
Federal AWQC for the protection of freshwater aquatic life and human health were used for
the development of cleanup standards for on-base surface waters (Table 6-1). These sites
consist of ditches which are tributaries to the Sacramento River, which have beneficial use
designation of municipal water supply and aquatic habitat.
Table 6-1. Chemical-Specific TBCs for Surface Water
Chemical
Aluminum
Barium
Chromium
Lead
Manganese
Silver
Vanadium
Zinc
Concentration (mg/L)
8.7 x 102 (1)
l.Ox 10° (2)
1.1 x 10'2 (1)
9.9 x 10'4 (1)
5.0 x 10'2 (3)
1.2x 10 4 (1)
l.Ox 10' (4)
4.9 x 102 (1)
Site Number
13
69
13, 15
13, 15
13, 15,69
13
15
13, 15
TBC = to-be-considered materials
mg/L = milligrams per liter
(1) U. S. Environmental Protection Agency National Ambient Water Quality Criteria, Freshwater Aquatic
Life Protection, Recommended Criteria, Continuous Concentration (four-day average).
(2) U. S. Environmental Protection Agency National Ambient Water Quality Criteria, Health and Welfare
Protection, Non-Cancer Public Health Effects.
(3) U. S. Environmental Protection Agency National Ambient Water Quality Criteria, Health and Welfare
Protection, Taste and Odor or Welfare.
(4) Agricultural Water Quality Goals
California Regional Water Quality Control Board Central Valley Region (CVRWQB), 1993, "A Compilation of
Water Quality Goals," Sacramento, California.
6.1.1.3 Groundwater
Section 121 of CERCLA indicates that remedial actions shall attain federal WQG or AWQC
where they are relevant and appropriate. National Primary Drinking Water regulation,
40 CFR Part 141, established MCLs and MCL goals for organic and inorganic constituents as
ARARs.
RL/10-95/ES/1260005.AWS
6-3
-------
6.1.2 State Chemical-Specific ARARs and TBCs
, The following State of California chemical-specific ARARs and TBCs have been identified.
6.7.2.7 Soils
There are no state chemical-specific ARARs for COCs found in the soils for the Soil OU sites.
To assure protection of human health and the environment chemical-specific TBCs were
developed from WQGs [CVRWQCB 1993]. The WQG was used as the regulatory factor for
each COC identified at a site. The WQG was multiplied by a teachability factor and an
environmental attenuation factor which are based on site-specific characteristics to develop a
TDL for each site-specific COC. The TDL methodology is described in the DLM guidance
document [CVRWQCB 1989]. The TBCs established for sediments, surface soils, and
subsurface soils are listed in Tables 6-2 through 6-4, respectively.
6.1.2.2 Surface Waters
There are no state chemical-specific ARARs or TBCs identified for surface waters. The
federal TBCs listed in Section 6.1.1.2, Table 6-1 were the most stringent requirements
identified for surface waters.
The beneficial uses of Mather Lake and Morrison Creek are not designated in the Basin Plan
specifically. However, the Basin Plan indicates that the beneficial use of these surface water
bodies should be municipal supply. Further, as a tributary of the Sacramento River, Morrison
Creek is assumed to have the same uses as the river (that is, municipal, agricultural,
recreational, and aquatic habitat). Based on this use-analysis, narrative standards for taste and
odor thresholds are considered TBC requirements.
6.1.2.3 Groundwater
The Porter-Cologne Water Quality Control Act is one of the statutory bases for remediation of
contaminants that threaten water quality in California. It establishes the authority of the State
Water Resources Control Board (SWRCB) and the CVRWQCB to protect the quality of
surface water and groundwater in California.
State Water Resources Control Board Resolution 68-16 has been identified as an applicable
requirement for the protection of surface water and groundwater of the state. The USAF and
the state do not agree on the full applicability of all the substantive requirements contained
within the resolution and the impact on the remedial activities needed to cleanup Mather AFB.
The USAF disagrees with the State's contention that the narrative language establishes
chemical-specific ARARs for both soil and groundwater, and that discharges subject to the
resolution include post-1968 migration of hi situ contamination from the vadose zone to
RL/IO-95/ES/1260005.AWS
6-4
-------
Table 6-2. Chemical-Specific ARARs and TBCs for Sediments
Chemical
Concentration (rag/kg)
Site Number
ARAR
PCBs (Aroclor 1248, 1254, and 1260)
5.0 x 10'
15
TBC*
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chlordane (alpha and gamma)
Chrysene
4,4-DDD
4,4-DDE
4,4-DDT
Dibenzo(a,h)anthracene
Dieldrin
Diesel
Fluoranthene
Fluorene
Gasoline
Indeno(l ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
2,3,7,8-TCDD equivalent
5.2 x 10°
2.8 x lO'5
2.8 x lO'5
2.8 x lO'5
2.8 x 10-5
2.8 x 10-5
2.8 x lO'5
2.8 x 10'5
5.7 x lO'6
2.8 x 10-5
8.3 x 10-5
5.9 x lO'5
5.9 x 10-5
2.8 x 10'5
1.4x 10'6
1.0x10°
3.7 x 10°
2.8 x 10'5
5.0 x 10-2
2.8 x 10-5
6.2 x 10°
6.3 x 10'2
9.6 x 10°
(1)
15
15
15
15
15
15
15
15
13, 15
15
13
13
13
15
13, 15
15
15
15
15
15
15
15
15
69
TBC*
Arsenic
Barium
Cadmium
Chromium VI •
Chromium, Total
Cobalt
Copper
l.SxlO-3
l.OxlO2
5.5 x lO'2
1.1x10°
1.1x10°
5.0 x 10°
1.3 x 103
13
15
15
13, 15
13, 15
13
13, 15
RL/10-95/ES/1260005.AWS
6-5
-------
Table 6-2. Chemical-Specific ARARs and TBCs for Sediments (Continued)
Chemical
Concentration (mg/kg)
Site Number
TBC* (Continued)
Lead
Mercury
Nickel
Vanadium
Zinc
9.9 x lO'2
1.2xlO-3
7.3 x 10°
l.Ox 10'
4.9 x 10'
4.9 x 10°
13, 15
13, 15
13
13
13
15
TBC = to-be-considered material
PCB = polychlorinated biphenyls
ODD = Dichlorodiphenyldichloroethane
DDT = Dichlorodiphenyltrichloroethane
ARAR = applicable or relevant and appropriate requirement
TCDD = tetrachlorodibenzo-p-dioxin
DDE = Dichlorodiphenyldichloroethene
mg/kg = milligrams per kilogram
(1) A Leachability Factor was not assigned and the total designated level was not calculated.
California Regional Water Quality Control Board Central Valley Region (CVRWQB), "A Compilation of Water
Quality Goals," 1993, Sacramento, California.
* Designated Level Methodology (DLM) value varies with site conditions (e.g., depth to groundwater) and
appropriate water quality objective. Appendix E of the Groundwater Operable Unit and Soil Operable
Unit Focused Feasibility Study Report [IT 1995a] shows how the site-specific DLM-based values were
derived, using appropriate teachability and environmental attenuation factors.
Table 6-3. Chemical-Specific TBCs for Surface Soils
Chemical
Concentration (mg/kg)
Site Number
TBC*
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h, i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Fluoranthene
Indeno(l ,2,3-cd)pyrene
Naphthalene
Pyrene
2,3,7,8-TCDD equivalent, total
Trichloroethene
Diesel
l.Ox ID'1
2.0 x 10'1
2.0 x 10-'
2.8 x 10'3
2.0 x 10-'
2.0 x lO'1
3.0 x 10-'
4.2 x 10' (2)
4.0 x 10-'
2.0 x 10'
9.6 x 102 (2)
(1)
5.0 x 10°
l.Ox 102
13, 56 .
56
56
13
62
56
56
13,62
13
13,62
13,62
11, 69
57
13, 39, 56, 62, 65
RL/10-95/ES/1260005.AWS
6-6
-------
Table 6-3. Chemical-Specific TBCs for Surface Soils (Continued)
Chemical
Arsenic
Barium
Cadmium
Chromium, Total
Lead
Manganese
Mercury
Zinc
Concentration (mg/kg)
5.0 x 102
l.Ox 104
5.0 x 10'
5.0 x 102
1.5xl02
5.0 x 102
2.0 x 10'
5.0 x 10s
Site Number
13,56
69
62
65
13, 20, 39, 56, 62, 65
69
13, 20
13, 20, 62, 69
TBC = to-be-considered material
mg/kg = milligrams per kilogram
TCDD = tetrachlorodibenzo-p-dioxin
* The Designated Level Methodology (DLM) value varies with site conditions (e.g., depth to groundwater)
and appropriate water quality objective. Appendix E of the Groundwater Operable Unit and Soil
Operable Unit l
-------
constituents that adversely affect its beneficial use. Table 6-5 lists the ARARs and TBCs for
drinking water and groundwater.
Table 6-4. Chemical-Specific TBCs for Subsurface Soils
Chemical
Concentration
(mg/kg)
Site Number
TBC*
Benzene
Benzo(a)pyrene
Chlordane (alpha and gamma)
4,4-DDE
4,4-DDT
Diesel
Ethylbenzene
Fluoranthene
Gasoline
Pyrene
Toluene
Trichloroethene
Xylenes
Cadmium
Lead
Mercury
Thallium
1.0x10-'
2.0 x 10-2
l.OxlO-2
l.OxlO'1
1.0x10°
l.OxlO1
l.OxlO2
2.9 x 10°
1.4xl03
5.0 x 10-'
5.0 x 10°
l.OSxlO2
4.2 x 10°
5.0 x 10-2
1.7 x 10°
1.7x10'
5.0 x 10°
1.5x10'
1.5 x 102
2.0 x 10°
2.0 x 10'
2.0 x 10°
39,54
62
13
13
13
7, 13, 20, 37, 39, 59, 62, 65
15,56
39
62
7, 39, 54, 59, 65
56,60
62
39
57
39
60
62
7, 13, 37, 65
56
13
15
7
TBC = to-be-considered material
DDT = dichlorodiphenyltrichloroethane
DDE = dichlorodiphenyldichloroethene
mg/kg = milligrams per kilogram
California Regional Water Quality Control Board Central Valley Region (CVRWQB), "A Compilation of Water
Quality Goals," 1993, Sacramento, California.
* Designated level methodology value varies with site conditions (e.g., depth to groundwater) and
appropriate water quality objective. Appendix E of the Groundwater Operable Unit and Soil Operable
Unit Focused Feasibility Study Report [IT 1995a] for how the site-specific DLM-based values were
derived, using leachability and environmental attenuation factors.
RL/IO-95/ES/1260005.AWS
6-8
-------
Table 6-5. Chemical-Specific ARARs and TBCs for Drinking and Groundwater
Chemical
Concentration (mg/L)
Plumes
ARAR
Benzene
Carbon Tetrachloride
1 ,4-Dichlorobenzene
1 ,2-Dichloroethane
1,1-Dichloroethene
cis-1 ,2-Dichloroethene
1 ,2-Dichloropropane
Tetrachloroethene
Trichloroethene
Vinyl Chloride
Xylenes
Lead
l.OxlO-3 (1)
5.0 x 10^ (1)
5.0 x 10-3 (1)
5.0 x 1Q-4 (1)
6.0 xlO'3 (1)
6.0 x 10-3 (1)
5.0 x 10'3 (2)
5.0 x lO'3 (2)
5.0 x 10-3 (2)
5.0 x IQ-4 (1)
1.75x10° (1)
1.5 xlO-2 (2)
MB/SAC, 7
MB/SAC, NE
7
MB/SAC, 7
MB/SAC, 7
MB/SAC, 7, NE
NE
MB/SAC, 7, NE
MB/SAC, 7
7
MB/SAC
MB/SAC
TBC
Chloromethane
TPH as Diesel '
TPH as Gasoline
3.0 x lO'3 (4)
l.OxlO'1 (3)
5.0 x lO'3 (3)
MB/SAC, 7, NE
MB/SAC, 7
MB/SAC
TBC = to-be-considered material
mg/L = milligrams per liter
SAC = Strategic Air Command
MB = Main Base
7 = Site 7
NE = Northeast
TPH = total petroleum hydrocarbon
ARAR = applicable or relevant and appropriate requirement
(1) Drinking Water Standards (California and Federal) Maximum Contaminant Levels (MCL), California
Department of Health and Services, Primary MCL.
(2) Drinking Water Standards (California and Federal) MCL, U.S. Environmental Protection Agency
(USEPA), Primary MCL.
(3) Other Taste and Odor Thresholds.
(4) Health Advisories or Suggested No-Adverse-Response Levels for toxicity other than cancer risk,
USEPA.
California Regional Water Quality Control Board Central Valley Region (CVRWQB), "A Compilation of Water
Quality Goals," 1993, Sacramento, California.
6.2 Location-Specific ARARs and TBCs
Location-specific ARARs and TBCs are requirements that place restrictions on the
concentration of a COC or the conduct of activities because of the presence of unique site
features such as surface waters and wetlands. The location of the Soil OU sites were analyzed
for unique site features to identify location-specific ARARs. The unique site
RL/10-95/ES/1260005.AWS
6-9
-------
features considered were:
• surface water;
• floodplain and wetlands;
• habitats of rare, threatened, endangered, and special status species;
• earthquake faults;
• historically or culturally significant properties;
• wilderness areas;
• wild and scenic rivers; and
• coastal zones.
Of these unique site features, surface water occurs at or near: Site 13 (Drainage Ditch
Number 1), Site 15 (Drainage Ditch Number 3), and Site 69 (Open Burn Pit). Portions of Site
7 may be located within the 100-year floodplain of Morrison Creek. Vernal pools and
seasonal wetlands, some of which are known to contain endangered species, have been
identified at Mather AFB. However, currently there has been no documentation that there are
wetlands likely to harbor endangered species at or near any of the remedial actions selected by
this ROD. The existence of wetlands and endangered species will be considered during
remedial design to avoid or minimize impact during activities such as location of electrical
conduit and water pipes associated with groundwater treatment systems. No other unique site
features were identified.
6.2.1 Federal Location-Specific ARARs
The Endangered Species Act and implementing regulations at 50 CFR 17, 222, 226, 227,
and 402, apply to some of the remedial actions at Mather AFB, if they impact endangered
wildlife. These impacts may be identified by a final biological assessment finding that the
vernal pools on Mather AFB, do contain an endangered species. No vernal pools have been
identified hi the vicinity of any of the Soil OU sites, for which remedial action is selected in
this ROD. The direct cleanup activities are not expected to impact any endangered species;
however, associated cleanup activities (i.e., construction of pipelines for groundwater
injection) may impact habitat or critical resources. All activities must ensure that regulatory
requirements are followed and impacts avoided or mitigated.
6.2.2 State Location-Specific ARARs
The Fish and Game Code Section 1600 requires that any work within the 100-year floodplain
(consisting of, but not limited to, diversion or obstruction of the natural flow or changes in the
RL/10-95/ES/1260005.AWS
6-10
-------
channel, bed, or bank of any river, stream or lake) will involve mitigation measures to avoid
or minimize impacts on natural resources. Portions of Site 7 may be located within the
100-year floodplain; certain provisions of the Fish and Game Code Section 1600 would be
relevant and appropriate for this site if the site is actually located in the 100-year floodplain.
RL/10-95/ES/1260005.AWS
6-11
-------
6.3 Action-Specific ARARs and TBCs
Action-specific ARARs are technology or activity-based requirements or limitations on actions
taken with respect to the hazardous waste. The following sections describe the state and
federal action-specific ARARs and TBCs. All ARARs are listed in Table 6-6 with each
substantive requirement identified as either applicable or relevant and appropriate. Several of
the requirements are marked with a footnote giving clarification to either their ARAR status or
the legal interpretation of why they are considered ARARs for a particular site or remedial
action. The TBCs are presented at the federal or state level in Sections 6.3.1.1 and 6.3.2.4.
Sections 6.3.1 and 6.3.2 include a description of the sources of the action-specific ARAR
regulations and the regulatory authority the agencies have to enforce these requirements. In
addition, the USAF position on substantive requirements of ARARs and how they apply to the
selected remedial actions are described.
6.3.1 Federal ARARs
The following federal action-specific ARARs and TBCs have been identified. The federal
action-specific ARARs are listed in Table 6-6, TBCs are listed in Sections 6.3.1.1 and 6.3.2.4
and a brief description of the sources of action-specific ARARs are provided in this section.
The Federal Safe Drinking Water Act regulates the injection of waste into injection wells.
These wells are identified by unique characteristics such as depth, location of drinking water
source, and material injected. Forty CFR 144 - Underground Injection Control Program is the
regulation listing the requirements for the operation and use of injection wells.
The California DTSC regulations promulgated under the Hazardous Waste Control Law
(HWCL) are applicable to RCRA-permitted storage facilities and proper characterization of
hazardous waste, and storage and disposal of such waste. There is only one RCRA permitted
facility (Site 37/39/54 - Building 3389/Hazardous Waste Central Storage Facility) being closed
under the remedial actions and there is no intention of building any to support the cleanup
activities. If any hazardous waste is identified, it will be disposed of and handled under the
permit by rule provisions of RCRA with treatment to render non-hazardous or disposed
offsite. Other HWCL provisions are relevant and appropriate to treatment systems, such as ex
situ bioremediation treatment cells, where soils are managed. Many of the HWCL provisions
are both relevant and appropriate because they describe requirements for the safe handling of
contaminated materials and precautions for preventing further contamination.
RL/10-95/ES/1260005.AWS
6-12
-------
C
9
Table 6-6. Action Specific ARARs
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
Fedei-ai AKARs
Federal Safe
Drinking Water
Act
40 CFR 144 - Underground Injection
Control Program
Applicable
USEPA established substantive requirements for actions that involve injection of fluids into
subsurface through wells. The injection can not cause a violation of primary MCLs, must be
maintained, must be monitored, and injection can not take place until the well construction is
complete.
This regulation applies to the technology selected for the cleanup of Main/SAC and Site 7
ground water plumes.
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 12
(Standards Applicable to Generators of
Hazardous Waste), Article 1
(Applicability)
Subsection(s)
as Listed
Below
Establishes standards for generators of hazardous waste located in California. Only applicable if the
wastes from excavated sites or treatment processes are classified as hazardous or non-RCRA
hazardous waste, and the remedial action constitutes treatment, storage, or disposal of hazardous
waste.
22CCR66262.il
Applicable
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 14
(Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article
6 (Water Quality Monitoring and
Response Programs for Permitted
Facilities)
Subsection(s)
as Listed
Below
22 CCR 66264.94(a)
Applicable
22 CCR 66264.96°
Applicable
These standards are applicable to permitted hazardous waste facilities. Owners or operators of
permitted hazardous waste facilities must monitor the groundwater during the closure and
post-closure periods. Groundwater Monitoring Requirements (22 CCR 66264.97): Groundwater
needs to be monitored during the closure and post-closure periods at permitted RCRA/HWCL
facilities. Corrective action monitoring (22 CCR 66264.100) is conducted if there is a corrective
action.
The concentration limit (22 CCR 66264.94(a)) may be background or established based on threats to
human health and the environment. If all of the wastes and contaminated materials are removed
from a waste management unit, monitoring should be continued until the groundwater results
indicate that all water levels are in compliance with the water quality standard for three consecutive
years (22 CCR 66264.96(c)).
These regulation sections are applicable to any RCRA corrective action at the treatment facility,
Site 39, which was the Hazardous Waste Central Storage Facility, which was permitted under
RCRA.
22 CCR 66264.97
Applicable
22 CCR 66264.100
Applicable
-------
TO
f
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Hazardous
Waste Control
Law
ON
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 14
(Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article
7 (Closure and Post-Closures)
Subsection(s)
as Listed
Below
22 CCR 66264.111
Applicable
22 CCR 66264.112(b)
Applicable
22 CCR 66264.114
Applicable
Closure Performance Standard (22 CCR 66264. Ill): Closure of a permitted hazardous waste
facility should minimize the need for maintenance of the facility, and control, minimize, or
eliminate emissions of hazardous chemicals into the environment.
Content of Closure Plan (22 66264.112(b)): All substantive steps required for closure of the facility
should be planned prior to beginning site activities. The time required for each step should be
estimated. Disposal or Decontamination of Equipment, Structure and Soils (22 CCR 662624.114):
All contaminated equipment, structures, and soils shall be properly disposed of or decontaminated.
Post-Closure Care and Use of Property (22 CCR 66264.117): Unless the contamination is totally
removed, monitoring and maintenance of the facility must be continued. Post-closure uses shall
never disturb containment systems or monitoring equipment.
These regulation sections are applicable to the corrective action under taken for facility closure at
the treatment facility, Site 39, which was the Hazardous Waste Central Storage Facility, which was
permitted under RCRA.
22 CCR 66264.117
Applicable
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 14
(Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article
9 (Use and Management of Containers)
Subsection(s)
as Listed
Below
22 CCR 66264.171
Applicable
22 CCR 66264.172
Applicable
22 CCR 66264.173
Applicable
22 CCR 66264.174
Applicable
The chemicals recovered from the sediments, surface soils, subsurface soils, or groundwater may
need to be managed as either a RCRA or non-RCRA hazardous waste. The treatment, storage, and
disposal requirements for these wastes are either applicable or relevant and appropriate (depending
upon the classification of the waste material) and they include: using containers to store the
recovered product that are compatible with this material (22 CCR 66264.172); using containers that
are in good condition (22 CCR 66264.171); segregating the waste from incompatible wastes (22
CCR 66264.177); inspect the containers (22 CCR 66264.174); isolating the waste from sources of
ignition (if the material is ignitable) and (22 CCR 66264.176); providing adequate secondary
containment for the waste stored (22 CCR 66264.175); containers must be closed during transfer
(22 CCR 66264.173); and all hazardous material must be removed at closure (22 CCR 66264.178).
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, the hazardous waste will be managed in accordance with the
standards stated in these sections of the regulation.
22 CCR 66264.175
Applicable
22 CCR 66264.176
Applicable
22 CCR 66264.177
Applicable
22 CCR 66264.178
Applicable
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 14
(Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article
12 (Waste Piles)
Subsection(s)
as Listed
below
22 CCR 66264.251
Applicable
22 CCR 66264.254
Applicable
Delineates requirements for the management of waste piles for hazardous waste. This regulation is
applicable to sites where excavated materials are classified as hazardous wastes and managed in
waste piles. The titles of the regulations are Section 66264.251. Design and Operating
Requirements; Section 66264.254. Monitoring and Inspection; Section 66264.256. Special
Requirements for Ignitable or Reactive Waste; Section 66264.257. Special Requirements for
Incompatible Wastes; Section 66264.258. Closure and Post-Closure Care; and Section 66264.259.
Special Requirements for Hazardous Wastes F020, F021, F022, F023, F026, and F027.
If during excavation, treatment processes, or cleanup activities, hazardous waste is identified
through the proper characterization process, and will be managed in waste piles, the hazardous
waste will be managed in accordance with the standards stated in these sections of the regulation.
22 CCR 66264.256
Applicable
22 CCR 66264.257
Applicable
22 CCR 66264.258
Applicable
22 CCR 66264.259
Applicable
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 14
(Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article
19 (Corrective Action for Waste
Management Units)
Subsection(s)
as Listed
Below
22 CCR 66264.552
Relevant and
Appropriate
22 CCR 66264.553
Relevant and
Appropriate
CAMU: Placement, consolidation, and treatment of soils and wastes being generated as part of a
corrective action under RCRA will not be considered a new disposal to land as long as the materials
are handled in designated CAMUs. Land disposal restrictions (22 CCR 66268) are not invoked
when remediation wastes are managed at a CAMU. A CAMU can only be used for the
management of remediation wastes pursuant to implementing corrective actions at the facility.
USEPA intended that the Federal CAMU rule be considered for the management of wastes
generated at CERCLA sites. Excavation of wastes from the discharge and disposal sites might be
managed at a CAMU for on-base disposal, or ex situ bioremediation.
A CAMU is an area within a facility for the purpose of implementing corrective actions.
Uncontaminated areas are allowed to be designated as part of a CAMU when they are necessary to
achieve the overall goals for the facility and will enhance the protectiveness of the remedial action.
The CAMU rule allows consolidation and treatment of wastes in a single unit, from other areas of
the facility, without triggering minimum technology requirements and LDR found in other
provisions of RCRA and HWCL: that is, placement of wastes into a CAMU is not considered land
disposal and redeposition of treated wastes into the CAMU does not trigger the LDRs.
Groundwater must be monitored at the CAMU in order to detect and characterize a release.
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, and will be managed in waste piles, the hazardous waste will be
managed in accordance with the standards stated in these sections of the regulation.
-------
9
a
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 18 (Land
Disposal Restrictions), Article 1
(General)
Subsection(s)
as Listed
Below
22 CCR 66268.3
Applicable
22 CCR 66268.7(a) & (b)
Applicable
Provides the purpose, scope, and applicability of LDRs. The tide of the sections of the regulations
are; Section 66268.3. Dilution Prohibited As a Substitute for Treatment; Section 66268.7. Waste
Analysis and Record keeping; and Section 66268.9. Special Rules Regarding Wastes That Exhibit a
Characteristic.
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, and will be managed in waste piles, the hazardous waste will be
managed in accordance with the standards stated in these sections of the regulation. Only applicable
if hazardous wastes are disposed of or treated in an area not designated as a CAMU or disposed of
or treated beyond the area of contamination.
22 CCR 66268.9
Applicable
California
Hazardous
Waste Control
Law
ON
i—»
O\
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 18 (Land
Disposal Restrictions), Article 3
(Prohibitions on Land Disposal)
Subsection (s)
as Listed
Below
22 CCR 66268.30
Applicable
22 CCR 66268.31
Applicable
22 CCR 66268.32
Applicable
These standards are applicable to sites where excavated material is classified as hazardous waste
and is disposed of or treated in an area not designated as a CAMU. Provides waste-specific LDRs
for Section 66268.30. Waste Specific Prohibitions-Solvent Wastes; Section 66268.31. Waste
Specific Prohibitions-Dioxin-Containing Wastes; Section 66268.32. Waste Specific
Prohibitions-California List Wastes; Section 66268.33. Waste Specific Prohibitions-First Third
Wastes; Section 66268.34. Waste Specific Prohibitions-Second Third Waste; and
Section 66268.35. Waste Specific Prohibitions-Third Third Waste.
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, and will be managed in waste piles, the hazardous waste will be
managed in accordance with the standards stated in these sections of the regulation.
22 CCR 66268.33
Applicable
22 CCR 66268.34
Applicable
22 CCR 66268.35
Applicable
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 18 (Land
Disposal Restrictions), Article 4
(Treatment Standards)
Subsection(s)
as Listed
Below
22 CCR 66268.41
Applicable
22 CCR 66268.42
Applicable
These standards are applicable to sites where excavated materials are classified as hazardous waste
and are disposed of or treated in an area not designated as a CAMU. Provides treatment standards
expressed in contaminant concentrations in Section 66268.41. Treatment Standards Expressed As
Concentrations in Waste Extract; Section 66268.42. Treatment Standards Expressed As Specified
Technologies; and Section 66268.43. Treatment Standards Expressed As Waste Concentrations.
These standards provide waste specific LDRs for solvent wastes, dioxin-containing wastes, and
California Listed Wastes.
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, and will be managed in waste piles, the hazardous waste will be
managed in accordance with the standards stated in these sections of the regulation.
22 CCR 66268.43
Applicable
-------
1
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Hazardous
Waste Control
Law
Title 22, Division 4.5 (Environmental
Health Standards for Management of
Hazardous Waste), Chapter 18 (Land
Disposal Restrictions), Article 5
(Prohibitions on Storage)
Subsection(s)
as Listed
Below
22 CCR 66268.50
Applicable
This standard is applicable to sites where excavated material is classified as hazardous waste. The
standard provides prohibitions on storage of restricted wastes.
If during excavation, treatment processes, or cleanup activities hazardous waste is identified through
the proper characterization process, and will be managed in waste piles, the hazardous waste will be
managed in accordance with the standards stated in these sections of the regulation.
Slate of California Air ARARi
California
Clean Air Act
O\
t—»
-J
SMAQMD, Rule 202, Section 301
Applicable
This section of the rule requires the installation of BACT to a new emissions unit or modification of
an existing emissions unit that will result in an emission of ROG, NOx, SOx, PM10, or CO.
Best Available Control Technology for any emission unit is the most stringent of the following:
The most effective emission control device, emission limit, or technique, singly or in combination,
which has been required or used for the type of equipment comprising such an emissions unit unless
the applicant demonstrates to the satisfaction of the SMAQMD that such limitations required on
other sources have not been demonstrated to be achievable. For this type of process, a control
efficiency (effluent/influent) of 95 percent is considered BACT.
Top-down analysis process is the selection of any alternative basic equipment, fuel, process,
emission control device, or technique, singly or in combination, determined to be technically
feasible and cost-effective by the SMAQMD.
In making a BACT determination for each affected pollutant the district may consider the overall
effect on other affected pollutants.
This regulation will apply to the treatment processes that release or cause to be released the
pollutants listed in the regulation. The remedial alternatives utilizing air strippers, soil vapor
extraction and ex situ bioremediation must ensure BACT is used to control emissions in excess of
levels specified in the rule.
-------
9
a
m
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Clean Air Act
SMAQMD, Rule 202, Section 302
Applicable
This section of the rule requires an applicant to provide offsets for any stationary source with the
potential to emit any pollutant in excess of the levels shown below.
ROG 1501bs/day
NOx 1501bs/day
SOx 1501bs/day
PM10....801bs/day
CO 5501bs/day
Offsets for CO shall not be required if the applicant can demonstrate that ambient air quality
standards will not be violated in the affected areas, and will not cause or contribute to a violation of
the ambient air quality standard. All emissions increases in excess of the levels specified above
need to be offset for the same calendar quarter.
Emissions are determined by using actual stack test data, emission factors, engineering calculations,
or other methods approved by the district in accordance with Section 411 of Rule 202.
This regulation will apply to the treatment processes that release or cause to be released the
pollutants listed in the regulation. The remedial alternatives utilizing air strippers, soil vapor
extraction and ex situ bioremediation must ensure offsets are used for emissions in excess of levels
specified in the rule.
California
Clean Air Act
SMAQMD, Rule 401
Applicable
This rule prohibits the discharge of air contaminants which obscure visibility by more than
20 percent for a period of more than three minutes in any one hour.
This regulation is applicable to any remedial action activity, which may cause a visible emission.
California
Clean Air Act
SMAQMD, Rule 402
Applicable
This rule prohibits the discharge of air contaminants in quantities which cause injury, detriment,
nuisance, or annoyance to any considerable number of persons or which endangers the comfort,
response, health, or safety of any such person or which causes or has natural tendency to cause
injury or damage to business or property.
This regulation is applicable to any remedial action activity, which may discharge air contaminants
as defined by the rule.
California
Clean Air Act
SMAQMD, Rule 403
Applicable
This rule requires a person to take every reasonable precaution not to cause or allow emissions of
fugitive dusts from being airborne beyond the property line from which the emissions originated.
This regulation is applicable to any remedial action activity, which may cause the release of fugitive
dust.
California
Clean Air Act
SMAQMD, Rule 404
Applicable
This rule prohibits the discharge of paniculate matter from any source in excess of 0.1 grains per
standard cubic foot.
This regulation is applicable to any remedial action activity , which may cause the release of
paniculate matter.
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Clean Air Act
SMAQMD, Rule 405
Applicable
This rule controls the discharge of dust and condensed fumes into the atmosphere by establishing
emission rates based on process weight.
This regulation is applicable to any remedial action activity, which may cause the release of dust or
condensed fumes.
State of California Groundwater and Soil ARARs
Federal Clean
Water Act
40 CFR 122 - USEPA Administered
Permit Programs: The National
Discharge Elimination System
40 CFR 122.26
Subsections(s)
as Listed
Below
Applicable
Requirements to ensure storm-water discharges from Mather AFB remedial action activities do not
contribute to a violation of surface water quality standards.
ON
H-i
VO
Federal Clean
Water Act
40 CFR 122 - USEPA Administered
Permit Programs: The National
Discharge Elimination System
Subsections(s)
as Listed
Below
40 CFR 122.41 (d)
Applicable
40 CFR 122.41(e)
Applicable
All reasonable steps must be taken to minimize or prevent discharges which have a reasonable
likelihood of causing adverse impacts on surface water quality (40 CFR 122.41(d)). All equipment
and facilities must be properly operated and maintained, including adequate laboratory controls and
appropriate quality assurance procedures (40 CFR 122.41(e)). Discharges into surface water must
achieve federal and state water quality standards (40 CFR 122.44(d)).
These sections of the regulation governing impacts to water quality apply to the groundwater
during/after treatment at the Main/SAC and Site 7 groundwater plumes.
40 CFR 122.44 (d)
Applicable
State Water Resources Board
Order 92-08-DWQ
Applicable
Must identify the sources of sediment and other pollutants that affect the quality of storm-water
discharges and implement practices to reduce these discharges.
Storm-water discharges from construction sites must meet pollutant limits and standards. The
narrative effluent standard includes the requirements to implement BMPs and/or appropriate
pollution prevention control practices.
Inspections of the construction site prior to anticipated storm events and after actual storm events
need to be conducted to identify areas contributing to storm-water discharge and evaluated for the
effectiveness of BMPs and other control practices.
Applies to construction sites fives acres or greater in size. It also applies to smaller sites that are
part of a larger common plan of development or sale.
The remedial actions at the groundwater sites are being conducted as part of the overall remedial
actions for Mather AFB. Excavation, grubbing, clearing, and other activities may be required for
installation of a groundwater extraction and treatment system.
-------
9
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
State Water Resources Board
Order 92-13-DWQ (as amended by
Order number 92-12-DWQ)
Applicable
Storm-water discharges must meet the narrative standard of the permit, this standard includes
implementing BMPs and prohibits the discharge of non-storm-water. Discharges should identify the
sources of pollutants to the storm-water. BMPs for these sources can include treatment of storm-
water discharge and source reduction. Non-storm-water sources of pollutants include improper
dumping, spills, and leaks.
Monitoring must be conducted to demonstrate compliance and measure the effectiveness of BMPs.
Monitoring includes performing visual inspections during the dry and wet seasons, conducting
annual inspections, and sampling and analysis for specific analytical parameters.
Applies to landfills, land application sites, and disposal sites (Site 7) that have received industrial
wastes, and other industrial areas.
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections 13000,
13140, 13240)
CVR Basin Plan
Applicable
Establishes water quality objectives, including narrative and numerical standards, that protect the
beneficial uses of surface and groundwater in the region. The designated beneficial uses are
municipal and domestic; agricultural; and industrial supply.
Specific applicable portions of the Basin Plan include beneficial uses of affected water bodies and
water quality objectives to protect those uses.
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections 13000,
13140, 13240)
SWRCB Resolution 68-16
Applicable
The resolution establish requirements for activities involving discharges of contamination directly
into surface waters or groundwater (e.g. quality of pump and treat effluent into surface waters or
groundwater).
Substantive requirements established by the resolution include use of "best practicable treatment or
control" for discharging the effluent.
This regulation applies to remedial action activities that cause active discharges to surface waters or
groundwater.
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections 13000,
13140, 13240)
SWRCB Resolution 88-63
Applicable
Specifies that, with certain exceptions, all ground and surface waters have the beneficial use of
municipal or domestic water supply. Applies in determining beneficial uses for waters that may be
affected by discharges of waste.
SWRCB Resolution 88-63 applies to all sites that may be affected by discharges of waste to
groundwater or surface water. The resolution specifies that, with certain exceptions, all
groundwater and surface waters have beneficial use of municipal or domestic water supply.
Consequently, California State primary MCLs are relevant and appropriate, however the most
stringent federal or state standard will be the ARAR for the remedial action. California standards
which may be ARARs for the site(s) are found in 22 CCR 66435, 22 CCR 64444.5, and 22 CCR
64473.
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections 13140,
13240, 13260,
13263, 13267,
13300, 13304,
13307)
SWRCB Resolution 92-49
(as amended April 21, 1994)
Subparagraph IIIG
Relevant and
Appropriate
Section IIIG directs the Water Boards to ensure dischargers clean up and abate the "effects" of
discharges in a manner promoting attainment of either background water quality or the best
reasonable water quality if background quality is not feasible (feasibility determined by factors listed
in Section IIIG and 23 CCR Chapter 15, Section 2550.4). Minimum water standards must be
protective of beneficial use.
Section IIIG directs the Water Board to apply 23 CCR Chapter 15, Section 2550.4 in approving any
alternative cleanup levels less stringent than background quality and to apply 23 CCR Chapter 16,
Section 2725 for alternatives cleanup levels for remediation of releases from USTs.
The requirement to obtain the Water Board's approval is not an ARAR; however, the Air Force will
consult with the Water Board and USEPA in applying the State's criteria to establish alternative
cleanup levels.
Subject to the limitations described above, this requirement is relevant and appropriate for
establishing levels for effects to surface and groundwater quality caused by releases of
contaminants.
O\
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 1 (General)
Subsection(s)
as Listed
Below
23 CCR 2510(g)'
Relevant and
Appropriate
23CCR2511(d)
Applicable or
Relevant and
Appropriate2
23 CCR 2510(g) states persons responsible for discharges at waste management units which are
closed, abandoned, or inactive on the effective date of these regulations may be required to develop
and implement a monitoring program in accordance with Article 5 of this Chapter. If water quality
impairment is found, such persons may be required to develop and implement a corrective action
program based on the provisions of this subchapter.
23 CCR 2511 (d) states actions taken by or at the direction of public agencies to cleanup or abate
conditions of pollution or nuisance resulting from unintentional or unauthorized releases of waste or
pollutants to the environment; provided that wastes, pollutants, or contaminated materials removed
from the immediate place of release shall be discharged according to Article 2 of this Chapter; and
further provided that remedial actions intended to contain such wastes at the place of release shall
implement applicable provisions of this subchapter to the extent feasible.
This regulation applies2 to waste management units located at Sites 7, 56, 57, 59, 60, 62, 65, and
69.
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Standard, Requirement, Criterion, or
Limitation
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article '2 (Waste Classification
and Management)
23 CCR 2520(a)
23 CCR 2520(b)
23 CCR 2520(c)
23 CCR 2520(d)
ARAR Status
Applicable or
Relevant and
Appropriate3'4
(See Sections
Listed Below)
Applicable to
Site 7
Applicable to
Site?
Applicable to
Site?
Applicable to
Site?
Description of Applicable or Relevant and Appropriate Requirements
Waste Classification: Wastes must be classified as either: hazardous waste (23 CCR 2521),
designated waste (23 CCR 2522), nonhazardous solid waste (23 CCR 2523), or inert waste
(23 CCR 2524). A hazardous waste can only be discharged to a Class I facility (unless a variance is
applicable under Title 22 regulations). A designated waste can be discharged to a Class I or Class
II facility. A nonhazardous solid waste can be discharged to a Class I, II, or III facility. Inert
wastes do not need to be sent to a classified facility.
Some of the sites have alternatives that involve excavation of the contaminated soil. At the
conclusion of on-base treatment, the soils are proposed for use hi the foundation layer of the landfill
cap at Site 4. It is expected based on engineering judgement that most of the sites excavated will
yield designated and not yield hazardous waste. However, until sampling is performed on the
material at time of excavation, a final determination cannot be made. The excavated waste must be
discharged to the appropriate facility pursuant to Article 2.
Requires that wastes identified as hazardous, designated, or nonhazardous solid waste (sections
2521, 2522 and 2523 of Article 2) be allowed only at waste management units which have been
approved and classified.
Prohibits the discharge of wastes which have the potential to reduce or impair the integrity of
containment structures or which, if commingled with other wastes in the unit, could produce violent
reaction, heat or pressure, fire or explosion, toxic by-products, or reaction products which in turn:
a. require a higher level of containment than provided by the unit;
b. are restricted 'hazardous wastes'; or
c. impair the integrity of containment structures.
Requires accurate characterization of waste.
Requires management of liquids at classified waste management units.
o\
N>
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Standard, Requirement, Criterion, or
Limitation
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 3 (Waste Management
Unit Classification and Siting)
23 CCR 2530(c)
23 CCR 2530 (d)
23 CCR 2532
23 CCR 2533(c)
Tide 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 4 (Construction
Standards)
23CCR2541(c)
23 CCR 254 l(d)
23 CCR 2546(a) & 2546(c) to (f)
ARAR Status
Subsection(s)
as Listed
Below
Applicable4'5
Applicable4'5
Applicable4'5
Relevant and
Appropriate to
Site?
Subsection(s)
as Listed
Below3
Relevant and
Appropriate to
Site?
Applicable to
Site?
Applicable to
Site?
Description of Applicable or Relevant and Appropriate Requirements
Classification and Siting Criteria (23 CCR 2530(c & d)): New waste piles shall be designed,
constructed, and operated to ensure that wastes will be a minimum of five feet above the highest
groundwater elevation. All containment structures at the unit shall have a foundation or base
capable of supporting the structures and capable of withstanding hydraulic pressure gradients.
Class II (23 CCR 2532): Waste Management Units for Designated Waste: Waste management units
will be isolated from the waters of the state through either natural or engineered barriers. The unit
needs to be able to withstand flooding without washout, ground rupture, and rapid geological
change.
Relevant to the ex situ bioremediation alternatives. Excavated wastes from various sites will be
spread in lifts in a bioremediation cell. Treatment might include nutrient addition, irrigation, and
aeration. This treatment is considered similar to a waste pile.
Soils containing petroleum hydrocarbons are not anticipated to be classified as hazardous, but may
be classified as designated wastes. Thus Class II requirements are considered most relevant.
Requires that landfills be designed, constructed, operated, and maintained to prevent inundation or
washout due to floods with a 100-year return period.
Requires hydraulic conductivities determined through laboratory methods be confirmed by
appropriate field testing.
Requires earthen materials used in containment structures consist of a mixture of clay and other
suitable fine- grained soils which have specified characteristics, and which can be compacted to
attain the required permeability when installed.
Requires management of precipitation and drainage control
ON
-------
70
C
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 5 (Water Quality
Monitoring and Response Programs for
Waste Management Units)
23 CCR 2550.1
23 CCR 2550.4
ON
to
23 CCR 2550.6
23 CCR 2550.7
23 CCR 2550.9
23 CCR 2550.10
Subsection(s)
as Listed
Below3
Relevant and
Appropriate
Relevant and
Appropriate6
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
These provisions of Chapter 15 address remediation of contamination at waste management units
and monitoring of groundwater quality during the remedial action. The corrective action program
requires that the cleanup objectives be met at the designated monitoring points and that they be met
throughout the zone that is affected. Further, demonstration of the effectiveness of the remediation
requires showing the concentrations at each monitoring point are at or below the cleanup levels for
one year following completion of the corrective action(s). The evaluation monitoring program
provides further substantive requirements regarding the designation of monitoring parameters and
monitoring frequency.
Section 23 CCR Part 2550.1 describes the three types of groundwater monitoring programs;
detection, statistical evaluation, and physical evaluation monitoring. Section 23 CCR Part 2550.10
(Corrective Action Program) requires that a groundwater monitoring program be implemented in
conjunction with a corrective action to demonstrate the effectiveness of the remedial technologies.
Both monitoring programs must meet the requirements outlined in Section 2550.7 which state:
-there is a sufficient number of monitoring points, including background points; and
-the monitoring points should be located at appropriate locations and screened in the zones of
concern.
Cleanup levels must be set at background concentration levels or, if background levels are not
technologically and economically feasible, then at the lowest levels that are economically and
technologically feasible. Specific factors must be considered in setting cleanup levels above
background levels. Cleanup levels above background levels shall be evaluated every five years. If
the actual concentration of a constituent is lower than its associated cleanup level, the cleanup level
shall be lowered to reflect existing water quality (23 CCR 2550.4). It has been determined that
cleanup to background is not economically feasible and therefore not relevant and appropriate to
aquifer cleanup standards.
Requires monitoring for compliance with remedial action objectives for three years from the date of
achieving cleanup levels (23 CCR 2550.6).
Requires general soil, surface water, and groundwater monitoring (23 CCR 2550.7)
Requires an assessment of the nature and extent of the release, including a determination of the
spatial distribution and concentration of each constituent (23 CCR 2550.9).
Requires implementation of corrective action measures that ensure that cleanup levels are achieved
throughout the zone affected by the release by removing the waste constituents or treating them in
place. Source control may be required. Also requires monitoring to determine the effectiveness of
corrective actions. To demonstrate cleanup, the concentration of each COC in the groundwater
must be equal to, or less than, the cleanup goal for at least one year following suspension of the
corrective action (23 CCR 2550.10).
-------
73
r^
9
Table 6-6. Action-Specific ARARs (continued)
Source
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Porter-Cologne
Water Quality
Control Act
(California
Water Code
Sections
13140-13147,
13172, 13260,
13263, 13267,
13304)
Standard, Requirement, Criterion, or
Limitation
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 8 (Closure and
Post-Closure Maintenance)
23 CCR 2580(a)
23 CCR 2580(d)
23 CCR 2580(e)
23 CCR 2581
Title 23 (Waters), Division 3 (State
Water Resources Control Board),
Chapter 15 (Discharges of Waste to
Land), Article 9 (Compliance
Procedures)
23 CCR 2596(b)
23 CCR 2597
ARAR Status
Subsections as
Listed Below3
Applicable
Relevant and
Appropriate
Relevant and
Appropriate
Applicable to
Site?
Subsections as
Listed Below3
Applicable to
Site?
Applicable to
Site?
Description of Applicable or Relevant and Appropriate Requirements
General Closure Requirements: partial or final closure of classified waste management units must
include continued maintenance of waste containment, precipitation, drainage controls, and
groundwater monitoring throughout the closure and post-closure periods (23 CCR 2580(a)). At
least two permanent monuments must be installed to allow the elevations of wastes, containment
structures, and monitoring facilities to be determined (23 CCR 2580(d)). Vegetation cover for a
closed waste management unit shall require minimum irrigation and maintenance, and shall not
impair the integrity of any containment structure (23 CCR 2580(e)).
The post-closure maintenance period will extend as long as wastes pose a threat to water quality.
This regulation applies to Site 7.
Requires a final cover constructed in accordance with specific prescriptive standards, to be
maintained as long as wastes pose a threat to water quality.
Regulation applies to closing solid waste disposal sites.
Procedures related to routine operations and emergency conditions must be developed for the waste
disposal activities.
Procedures for closure and post-closure maintenance must be developed. The magnitude of
settlement due to waste decompsition and compaction and subsidence of the underlying natural
geologic materials must be estimated. If the post-closure use is not non-irrigated open space, the
water balance for the site must be estimated and adverse impacts on the final cover anticipated.
State of California Solid Waste ARARs
California Inte-
grated Waste
Management
Act of 1989
PRC 40502,
43020,43021
and 43030
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 3
(Minimum Standards for Solid Waste
Handling and Disposal), Article 7.3
(Disposal Site Records)
14 CCR 17636
14 CCR 17637
Subsections as
Listed Below
Applicable
Applicable
This regulation is applicable to solid waste disposal sites as defined by Public Resources Code
Section 40122, i.e. for waste consolidation at Site 7.
Weight/Volume Records: the weight or volume of waste accepted must be determined to an
accuracy of ±10%
Subsurface Records: the length and depth of any cut(s) made in natural terrain where fill will be
placed and the depth to groundwater must be determined and documented.
-------
73
c
9
S
m
Table 6-6. Action-Specific ARARs (continued)
Source
California Inte-
grated Waste
Management
Act of 1989
PRC 40502,
43020,43021
and 43030
California Inte-
grated Waste
Management
Act of 1989
PRC 40502,
43020, 43021
and 43030
Standard, Requirement, Criterion, or
Limitation
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 3
(Minimum Standards for Solid Waste
Handling and Disposal), Article 7.4
(Disposal Site Improvements)
14 CCR 17658
14CCR 17659
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 3
(Minimum Standards for Solid Waste
Handling and Disposal), Article 7.5
(Disposal Site Operations)
14 CCR 17676
14 CCR 17677
14 CCR 17678
14 CCR 17680
14 CCR 17684
14 CCR 17686
14 CCR 17687
14 CCR 17688
14 CCR 17689
14 CCR 17690
14 CCR 17691
14 CCR 17692
ARAR Status
Subsections as
Listed Below
Applicable
Applicable
Subsections as
Listed Below
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Description of Applicable or Relevant and Appropriate Requirements
This regulation is applicable to solid waste disposal sites as defined by Public Resources Code
Section 40122, i.e. for waste consolidation at Site 7.
Site Security: the perimeter of the landfill must be secured either through barriers or topographic
constraints to discourage unauthorized entry.
Access Roads: landfill roads must be reasonably smooth to minimize dust and tracking of materials
onto public roads.
This regulation is applicable to solid waste disposal sites as defined by Public Resources Code
Section 40122, i.e. for waste consolidation at Site 7.
Confined Unloading: Requires limiting unloading area, controlling windblown materials, and
deposition at toe of fill.
Spreading and Compacting: Requires spreading and compacting of refuse in layers.
Slopes and Cuts: The slope of the working face shall be maintained at a ratio which will allow
effective compaction of the wastes. The depth of cuts and slopes of trench sides shall not exceed
specified horizontal to vertical ratios.
Stockpiling: Requires stockpiled cover material and unacceptable native materials to be placed so as
not to cause problems or interference with site operations.
Intermediate Cover: Requires cover on fill where no additional refuse will be deposited within 180
days.
Scavenging: Scavenging is prohibited.
Salvaging Permitted: Salvaging is permitted in a planned and controlled manner.
Volume Reduction and Energy Recovery: Volume reduction and energy recovery are permitted in
planned and controlled manners.
Processing Area: Processing area shall be confined to greatest degree practicable.
Storage of Salvage: Salvage material must be safely isolated for storage.
Removal: Storage time for salvage materials shall be limited to a safe duration.
Non-Salvageable Items: Items capable of impairing public health shall not be salvaged without
approval by Enforcement Agency and local health entity.
-------
Table 6-6. Action-Specific ARARs (continued)
Source
California Inte-
grated Waste
Management
Act of 1989
PRC 40502,
43020,43021
and 43030
Standard, Requirement, Criterion, or
Limitation
Title 14 (Natural Resources), Division 7
(California IWMB), Chapter 3
(Minimum Standards for Solid Waste
Handling and Disposal), Article 7.6
(Disposal Site Controls)
14 CCR 17701
14CCR 17704
14 CCR 17705
14 CCR 17706
14 CCR 17707
14 CCR 17708
14 CCR 17709
14 CCR 17710
14 CCR 17711
14 CCR 17713
14 CCR 17741
ARAR Status
Subsections as
Listed Below
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Description of Applicable or Relevant and Appropriate Requirements
This regulation is applicable to solid waste disposal sites as defined by Public Resources Code
Section 40122, i.e. for waste consolidation at Site 7.
Nuisance Control: Each site shall be operated and maintained so as not to create a public nuisance.
Leachate Control: The operator shall take adequate steps to monitor, collect, treat, and effectively
dispose of leachates.
Gas Control: Landfill gas control may be required based on the monitoring results.
Dust Control: The operator shall take adequate measures to minimize the creation of dust.
Vector and Bird Control: The operator shall control or prevent the propagation, harborage, or
attraction of flies, rodents, or other vectors, and to minimize bird problems.
Drainage And Erosion Control: Adequate drainage shall be provided. Effects of erosion shall be
promptly repaired and steps taken to prevent further occurrence.
Contact with Water: No solid waste shall be deposited in direct contact with surface water.
Grading of Fill Surface: Covered surfaces of the disposal area shall be graded to promote run-off and prevent
ponding, accounting for future settlement
Litter Control: Litter and loose materials shall be routinely collected and disposed of properly.
Odor Control: The disposal site shall not be a source of odor nuisances.
Burning Wastes: Burning wastes shall be extinguished.
ON
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
ON
Ni
oo
California
Integrated
Waste
Management
Act of 1989
Public
Resources Code
Sections 40502
and 43020
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 3
(Minimum Standards for Solid Waste
Handling and Disposal), Article 7.8
(Disposal Site Closure and Post-Closure
Maintenance)
Subsection(s)
as Listed
Below
The regulation is applicable to solid waste sites that closed after August 1988. Although never
classified as a landfill under California regulations, Site 7 was used for the disposal of POL and
other industrial wastes. The wastes discarded at Site 7 are likely to be classified as designated
wastes using the criteria in effect in 1994 (23 CCR 2520-2523). Because of the similarity of
historical activities and site conditions at Site 7 to a landfill, Article 7.8 regulations are considered
relevant and appropriate.
14 CCR 17766
Relevant and
Appropriate
ERP: Potential emergency conditions that may exceed the design of the site and could endanger the
public health or environment must be anticipated. Procedures for mitigation of these conditions
should be developed (14 CCR 17766).
14 CCR 17767
Relevant and
Appropriate
Security at Closed Sites: All points of access to the site must be restricted, except permitted entry
points. All monitoring, control, and recovery systems shall be protected from unauthorized access
(14 CCR 17767).
14 CCR 17773(b)
Relevant and
Appropriate
14 CCR 17773(c)
Relevant and
Appropriate
Final Cover: The design and construction of the final cover must meet specific prescriptive
standards (references 23 CCR 2581(a)). These include minimum thickness and quality of the
construction material (14 CCR 17773 (b) and (e)). If the prescriptive standards are not feasible,
engineered alternatives can be approved provided that they are consistent with the performance
goals and afford equivalent protection against water quality impact (14 CCR 17773 (b, c, d, e)).
14 CCR 17773(d)
Relevant and
Appropriate
14 CCR 17773(e)
Relevant and
Appropriate
-------
71
C
9
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
California
Integrated
Waste
Management
Act of 1989
Public
Resources Code
Sections 40502
and 43020
14 CCR 17774(a)
14 CCR 17774(C)
14 CCR 17774(d)
14 CCR 17774(e)
14 CCR 17774 (f)
14 CCR 17774(g)
14 CCR 17774(h)
14 CCR 17776(a)
14 CCR 17776(c)
14 CCR 17776(e)
14 CCR 17776(f)
14 CCR 17777(a)
14 CCR 17777(b)
14 CCR 17777(c)[portions]
Relevant and
Appropriate
Relevant and
Appropriate
CQA: A CQA program must be designed and implemented. It must include specific parameters
(and for some components specific testing methods) for each component of the final cover (14 CCR
17774(a, c - h)).
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Final Grading: The final grades for the covered landfill must meet grading standards provided in
23 CCR 2581(b), they must be appropriate to control runoff and erosion. Two monuments must be
installed to assess changes in the grade pursuant to 23 CCR 2581(d) (14 CCR 17776(a, c, e, f)).
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Final Site Face: The design of the final site face must provide for the integrity of the final cover
under both static and dynamic conditions. The design of the final face must achieve a safety factor
of 1.5 under dynamic conditions. This evaluation must consider the critical slope, the engineering
properties of the foundation materials, refuse, and other layers making up the site, the maximum
expected horizontal acceleration in rock, and other seismic shaking parameters (14 CCR 17777(a, b,
cfportions])).
-------
XJ
c
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
14 CCR 17778(a)
14 CCR 17778(c)
14 CCR 17778(d)
14 CCR 17778(e)
14 CCR 17778(0
14 CCR 17778(g)
14 CCR 17778(h)
14 CCR 17778(i)
14 CCR 17778(j)
14 CCR 17779
14 CCR 17781
14 CCR 17783
14 CCR 17788
ARAR Status
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Description of Applicable or Relevant and Appropriate Requirements
Final Drainage: The design of the final cover must control runon and runoff produced by a
100-year, 24-hour storm event and must be prepared according to CQA requirements. The runon
and runoff control systems must be designed and constructed in accordance with 23 CCR 2546(c)
and (d). The runoff collection and holding facilities must perform pursuant to requirements in
23 CCR 2546(d) (14 CCR 17778(a, c -j).
Slope Protection and Erosion Control: The design and construction of the slopes must protect the
integrity of the final cover and minimize soil erosion (14 CCR 17779).
Leachate Control During Closure and Post-Closure: Leachate must be monitored, collected,
treated, and discarded appropriately. The state does not intend that subsurface leachate monitoring
and collection systems need to be added to existing landfills unless leachate production and/or
accumulation is evident (14 CCR 17781).
Gas Monitoring and Control During Closure and Post-Closure: Landfill gases must be collected and
analyzed; the concentration of combustible gas at the landfill boundary must be five percent or less,
and trace gases must not be at levels that cause adverse health or environmental impacts.
Monitoring should be conducted for 30 years or until authorized to be discontinued by showing that
methane is no longer produced. Methane was not detected in the landfill gas survey conducted in
1988. Measurable (ppb to ppm) levels of benzene and chlorinated hydrocarbons were found in the
soil gas (14 CCR 17783).
Post-Closure Maintenance: The landfill must be maintained and monitored for no less than 30 years
following closure. Monitoring would continue for 30 years following closure unless it can be
demonstrated that the landfill does not pose a threat to public health and safety or to the
environment. If the threat has been eliminated, post-closure maintenance can be discontinued
(14 CCR 17788).
ON
UJ
o
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
14 CCR 17796(c)
Relevant and
Appropriate
14 CCR 17796(d)
Relevant and
Appropriate
Post-Closure Land Use: Site closure design shall show one or more proposed uses of the closed site
or show development that is compatible with open space (14 CCR 17796(c, d, f))-
Construction improvements will be compatible with closure and post-closure requirements and any
new activities must not increase the potential threat to public health and safety.
14 CCR 17796(f)
Relevant and
Appropriate
14 CCR 17796(c)
Relevant and
Appropriate
14 CCR 17796(d)
Relevant and
Appropriate
Post-Closure Land Use: Site closure design shall show one or more proposed uses of the closed site
or show development that is compatible with open space (14 CCR 17796(c, d, f))-
Construction improvements will be compatible with closure and post-closure requirements and any
new activities must not increase the potential threat to public health and safety.
14 CCR 17796(f)
Relevant and
Appropriate
California
Integrated
Waste
Management
Act of 1989
Public
Resources Code
Sections 40502
and 43509
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 5
(Enforcement of Solid Waste Standards
and Administration of Solid Waste
Facilities Permits; Loan Guarantees),
Article 3.2 (Reports of Facility
Information)
Subsection(s)
as Listed
Below
Provides the minimum standards for closure of a solid waste disposal site (Section 18262.3.
Contents of the Final Closure Plan and Section 18265.3. Contents of the Final Post-Closure
Maintenance Plan). Applies to solid waste disposal sites that received waste after January 1, 1988.
14 CCR 18222
Relevant and
Appropriate
Report of Disposal Site Information: The planning and procedural requirements necessary to ensure that solid
waste is handled and disposed in manners that protect public health and safety and the environment must be
conducted.
California
Integrated
Waste
Management
Act of 1989
Public
Resources Code
Sections 40502
and 43509
Title 14 (Natural Resources), Division 7
(California Integrated Waste
Management Board), Chapter 5
(Enforcement of Solid Waste Standards
and Administration of Solid Waste
Facilities Permits; Loan Guarantees),
Article 3.4 (Application and Approval of
Closure and Post-Closure Maintenance
Plans)
Subsection(s)
as Listed
Below
Provides the minimum standards for closure of a solid waste disposal site (Section 18262.3.
Contents of the Final Closure Plan and Section 18265.3. Contents of the Final Post-Closure
Maintenance Plan). Applies to solid waste disposal sites that received waste after January 1, 1988.
14 CCR 18262.3
Relevant and
Appropriate
14 CCR 18265.3
Relevant and
Appropriate
-------
Table 6-6. Action-Specific ARARs (continued)
Source
Standard, Requirement, Criterion, or
Limitation
ARAR Status
Description of Applicable or Relevant and Appropriate Requirements
Other Stale of California ARARs V; : :
40 CFR 122
122.26
Fish and Game Code
Sections 5650
Section 5652
Subsection(s)
as Listed
Below
Relevant and
Appropriate
Relevant and
Appropriate
It is unlawful to deposit in, permit to pass into, or place where it can pass into the waters of this
slate any material listed in Fisli and Game Code Sections 5650 and 5652.
Os
U)
to
CCR = California Code of Regulation
ERP = Emergency Response Plan
ROG = reactive organic gas
CO = carbon monoxide
CFR = Code of Federal Regulation
RCRA = Resource Conservation and Recovery Act
AFB = Air Force Base
CAMU = Corrective Action Management Unit
USEPA = United States Environmental Protection Agency
HWCL = Hazardous Waste Control Law
POL = petroleum, oil, and lubricant
NOx = nitrogen oxide
CVR = Central Valley Region
MCL = maximum contaminant level
BMP = Best Management Practice CQA = Construction Quality Assurance
UST = underground storage tanks LDR = land disposal restrictions
SOx = sulfur oxide PM10 = paniculate matter
ppm = parts per million ppb = parts per billion
COC = contaminant of concern SAC = Strategic Air Command
ARAR = applicable or relevant and appropriate requirement BACT = Best Available Control Technology
DWQ = Department of Water Quality SWRCB = State Water Resource Control Board
SMAQMD = Sacramento Metropolitan Air Quality Management District
CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act
1. Only as invoked through 23 CCR 2511(d) for action intended to contain waste in place.
2. 23 CCR 251 l(d) is applicable to waste management units in operation after November 27, 1984, and relevant and appropriate for units whose operations ceased prior to November 27, 1984.
3. Only as invoked by 23 CCR 2511 (d).
4. The regulation is applicable to waste removed from waste management units and relevant and appropriate for waste removed from other sites/units.
5. Only as invoked through 23 CCR 251 l(d) and 23 CCR 2520(a)(2).
6. Only as invoked by 92-49 IIIG.
-------
The following chapters of Title 22, Division 4.5 Environmental Health Standards for
Management of Hazardous Waste, have been identified as ARARs for remedial action sites at
Mather AFB: Chapter 12 - Standards Applicable to Generators of Hazardous Waste, Article 1
- Applicability; Chapter 14 - Standards for Owners and Operators of Hazardous Waste
Transfer, Treatment, Storage, and Disposal Facilities; Article 6 - Water Quality Monitoring
and Response Programs for Permitted Facilities; Article 7 - Closure and Post Closure; Article
9 - Use and Management of Containers; Article 12 - Waste Piles; Article 19 - Corrective
Action for Waste Management Units; Chapter 18 - Land Disposal Restrictions, Article 1 -
General; Article 3 - Prohibitions on Land Disposal; Article 4 - Treatment Standards; and
Article 5 - Prohibitions on Storage.
6.3.1.1 Other Federal Regulations
The TSCA delineates the requirements for excavation of PCBs and sampling activities
associated with PCB removal through 40 CFR Part 761. These requirements are TBCs for the
excavation and removal of PCB contaminated soils. This guidance is used to establish
minimum depths and area for cleanup as outlined in the regulation. Site 15 is the only site
where PCBs are COCs, and the material is below the 50 ppm level specified in the regulation.
The identified alternative will excavate the material and dispose of it at Site 4 or Site 7, as
appropriate, as foundation material for a landfill cap.
6.3.2 State ARARs and TBCs
The following California statutes, laws, and regulations have been identified as ARARs and
TBCs. The following subsections list the ARARs and TBCs in the following order: air,
water, waste, and other state regulations. The state action-specific ARARs are listed in
Table 6-6, TBCs are listed in the text under other regulations and a brief description of the
source of the ARARs are listed along with the regulations derived under the source. Also
presented is the USAF position on substantive requirements of these ARARs and how they
apply to the selected remedial actions.
6.3.2.1 State Air ARARs
The California Clean Air Act, under the Federal Clean Air Act and 1990 Amendments,
authorizes the State of California to develop a State Implementation Plan (SIP) to enforce clean
air regulations and laws. The SIP, developed through state legislation, divided the state into
local air control districts and allowed each district to enforce the requirements of the federal
and state Clean Air Acts. Mather AFB is located in the Sacramento Metropolitan Air Quality
Management District (SMAQMD); state air regulations are the most stringent
RL/IO-95/ES/1260005.AWS
6-33
-------
ARARs. The SMAQMD applicable regulations are: Rule 202, Section 301 - Best Available
Control Technology; Section 302 - Offsets; Rule 401 - Visible Emissions; Rule 402 -
Nuisance; Rule 403 - Fugitive Dust; Rule 404 - Particular Matter; and Rule 405 - Dust and
Condensed Fumes. Table 6-6 contains the applicable or relevant and appropriate sections of
these regulations identifying the ARAR status and a brief description of the substantive
requirements and applicability to either the site, remedial action, or technology used to cleanup
the site and contaminated material.
6.3.2.2 State Groundwater and Soil ARARs
The Federal Clean Water Act regulates discharge to surface waters and groundwater. Under
this statute is the 40 CFR 122 - USEPA Administrative Permit Program: National Discharge
Elimination System regulation for stormwater and other discharges to surface waters. This
program is delegated to the state under the statute and therefore is considered a state ARAR.
The SWRCB has issued two general orders under the federal statute, Clean Water Act, that
provides the substantive requirements for stormwater management at industrial sites
(SWRCB Order 92-13-DWQ) and construction sites (SWRCB Order 92-08-DWQ). The
substantive requirements for industrial sites are meeting the narrative water quality standards,
implementing best management practices, identifying and monitoring sources of stormwater
pollutants, and eliminating non-stormwater sources of pollutants. The substantive requirements
associated with construction activities such as excavation and grading include application of
engineering measures and best management practices to control stormwater runoff.
The Porter-Cologne Water Quality Control Act is one of the statutory bases for regulation of
discharges of waste to land that could impair either surface water or groundwater quality in
California. It establishes the authority of the SWRCB and the CVRWQCB to protect the
quality of surface water and groundwater. The California Water Code sections used as a
source for action-specific ARARs and TBCs are presented in Table 6-6 along with the
associated regulatory citations. Under the Porter-Cologne Act the following regulations or
resolutions regulating and protecting the waters of the state are considered relevant and
appropriate and are therefore ARARs: Central Valley Region (CVR) Basin Plan; SWRCB
Resolution 68-16; SWRCB Resolution 88-63; and SWRCB Resolution 92-49; California
Title 23, Chapter 3, SWRCB, Subchapter 15 - Discharges of Waste to Land, Article 1 -
General; Article 2 - Waste Classification and Management; Article 3 - Waste Management
Unit Classification and Siting; Article 5 - Water Quality Monitoring and Response Programs
RL/IO-95/ES/1260005.AWS
6-34
-------
for Waste Management Units; Article 8 - Closure and Post-Closure Maintenance; and
Article 9 - Compliance Procedures. Table 6-6 contains the applicable or relevant and
appropriate sections of these regulations identifying the ARAR status and a brief description of
the substantive requirements and applicability to either the site, remedial action, or technology
used to clean up the site and contaminated material.
State Water Resources Control Board Resolution 68-16 has been identified as an applicable
requirement for the protection of surface waters and groundwater of the state. The USAF and
the state do not agree on the full substantive requirements of this resolution and the impacts on
the remedial action activities need to cleanup Mather AFB. The USAF disagrees with the
state's contention that the narrative language establishes chemical-specific ARARs for both
soils and groundwater, and that discharges subject to the resolution include post-1968
migration of in situ contamination from the vadose zone to groundwater. The USAF believes
that discharges only encompass remedial activities that actively discharge to surface water and
groundwater of the state.
According to the decision of the USEPA Administrator, SWRCB Resolution 68-16, the water
anti-degradation policy, is a state ARAR for the establishment of numerical limits for the
reinjection of treated groundwater into clean areas (i.e., high quality waters) of the aquifer,
(i.e., outside of the contaminated plume). The numerical limits established on a monthly
median and on a daily maximum basis to meet the requirements of SWRCB Resolution 68-16
are set forth in Table 6-7. With respect to the injection of treated groundwater within the
contaminated plume, treatment shall be such that the concentration level of the contaminant in
the groundwater must not exceed the concentration in the groundwater at the point of injection
measured on a monthly median basis and also not exceed the federal and state ARAR. With
respect to injection of treated groundwater outside the contaminated plume, the effluent is
required to meet daily and 30-day median concentrations for each COC as shown in Table 6-7.
To meet the requirement that the selected remedy be protective of human health and the
environment, the USAF shall maintain hydraulic control of the plume while extracting
contaminated groundwater, and reinjecting treated groundwater into the contaminant plume or
the clean portion of the aquifer.
RL/10-95/ES/1260005.AWS
6-35
-------
Table 6-7. Groundwater Discharge Treatment Standards
Constituent
Main Base/SAC Ind. Plume
Benzene
CCi,
Chloromethane
1,2-DCA
1,1 -DCE
Cis-l,2-DCE
Lead
PCE
TPH-G
TPH-D
TCE
Xylene
Site 7 Plume
Benzene
Chloromethane
1,2-DCA
1.1-DCE
Cis-1.2-DCE
1,4-DCB
PCE
TPH-D
TCE
Vinyl Chloride
Standard for Injection into
Noncontaminated Portions of the
Aquifer Based on State Board
Resolution 68-16 0*g/l)
30 Day Median
0.5
0.5
0.5
0.5
0.5
0.5
Background
0.5
50.0
50.0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
50.0
0.5
0.5
Daily Maximum
0.5(1)
0.5 (2)
3.0
0.5 (3)
6.0
6.0
15.0
0.7 (4)
50.0
100.0
2.3 (5)
17.0
0.5(1)
3.0
0.5 (3)
6.0
6.0
0.88 (7)
0.7 (4)
100.0
2.3 (5)
0.5 (6)
Standards for Injection in the Contaminated Portions
of the Aquifer Based on the more Stringent of
(a)MCL's (State or Federal) whichever is more
stringent or (b)In Situ Groundwater Concentrations at
the Point of Injection as 30 Day Median (j*g/l)
Class of Carcinogens
A
B2
C
B2
C
D
-
B2
-
-
B2
D
A
C
B2
C
D
C
B2
-
B2
C
Slate or Federal MCLs
Daily Maximum
1.0 (CA-MCL)
0.5 (CA-MCL PQL)
3.0 (SNARL)
0.5 (CA-MCL PQL)
6.0 (CA-MCL)
6.0 (CA-MCL)
15.0 (FMCL)
S.O(FMCL)
50.0 (PQL)
100.0 (US EPA HA)
5.0 (FMCL)
17.0 (TO)
1.0 (CA-MCL)
3.0 (SNARL)
0.5 (CA-MCL PQL)
6.0 (CA-MCL)
6.0 (CA-MCL)
5.0 (CA MCL)
5.0 (FMCL)
100.0 (US EPA HA)
5.0 (FMCL)
0.5 (CA MCL PQL)
(1) California Environmental Protection Agency (CA EPA), Cancer Potency Factor as a Water Quality Criterion = 0.35 ^g/1, U. S.
Environmental Protection Agency (USEPA) Integrated Risk Information System (IRIS) = 1.0 /^g/l
(2) CA EPA. Cancer Potency Factor as a Water Quality Criterion = 0.23 Mg/1. USEPA IRIS = 0.3 ^g/1
(3) CA EPA. Cancer Potency Factor as a Water Quality Criterion = 0.5 Mg/1, USEPA IRIS = 0.4 ^tg/1
(4) CA EPA. Cancer Potency Factor as a Water Quality Criterion = 0.69 j/g/i, USEPA IRIS = 0.7 ^g/1
i5) CA EPA. Cancer Potency Factor as a Water Quality Criterion = 2.3 ng/l, USEPA IRIS = 3.0 ^g/l
(6) CA EPA, Cancer Potency Factor as a Water Quality Criterion = 0.13 /^g/i. USEPA IRIS = 0.015 ng/l
(7) CA EPA, Cancer Potency Factor = 0.88 Mg/1
California Regional Water Quality Control Board Central Valley Region (CVRWQB),
Sacramento, California.
'A Compilation of Water Quality Goals," 1993,
CA-MCL = Drinking Water Standards, California Department of Health Services, Primary Maximum Contaminant Level (MCL)
SNARL = Health Advisory or Suggested No-Adverse-Response Levels for Toxicity other than cancer risk
FMCL = Drinking Water Standards, U. S. Environmental Protection Agency, Primary MCL
US EPA HA = Health Advisories or SNARLs for toxicity other than cancer risk, U. S. Environmental Protection Agency
TO = Other Taste & Odor Thresholds PQL = Practical Quantitation Limit CC\t = carbon tetrachloride
PCE = tetrachloroethene TCE = trichloroethene DCA = dichloroethane DCE = dichloroethene
TPH-G = total petroleum hydrocarbons as gasoline TPH-D = total petroleum hydrocarbons as diesel ng/1 = micrograms per liter
A = Known human carcinogen; sufficient epidemiologic evidence in humans. B2 = Probable human carcinogen; limited
epidemiologic evidence in humans. C = Possible human carcinogen; limited evidence from animal studies; no human data.
D = Not classified as to human carcinogenity; no data or inadequate evidence.
RL/10-95/ES/1260005.AWS
6-36
-------
The USAF is currently studying the potential relevance and appropriateness of SWRCB
Resolution 92-49 as it pertains to USAF IRP activities within the state. The only section with
substantive requirements appears to be Section IIIG. Section IIIG is the only provision of
SWRCB Resolution 92-49 that arguably is relevant and appropriate in establishing
water-related cleanup levels under limited circumstances yet to be determined. The portion of
Section IIIG, through incorporation of certain provisions in Titles 22 and 23 CCR, that creates
a presumption of media cleanup resulting in background groundwater concentration levels is
not generally a relevant and appropriate requirement for groundwater or vadose zone cleanup
levels. The USAF hopes to eventually resolve the ARAR status of SWRCB Resolution 92-49
through ongoing discussions with its U.S. Department of Defense counterparts, USEPA, and
the state. For purposes of this ROD, the USAF believes that if vadose zone contamination
overlies a groundwater plume, that remediation of the COCs in the groundwater satisfies the
requirement of Section IIIG to abate the effects of discharge. In that situation, Section IIIG is
not a relevant and appropriate requirement for the remediation of the vadose zone, even
though technical considerations, risk, cost-effectiveness, and other remedy-selection factors
may warrant concurrent remediation of the vadose zone to promote the groundwater
remediation. If these factors warrant concurrent vadose zone remediation, the USAF will
conduct such remediation but not based on the premise that Section IIIG requires such action.
The state's position is that SWRCB Resolution 92-49 is an applicable requirement for remedial
actions in the vadose zone where there is an impact, or a threat of an impact, to the beneficial
uses of the groundwater or surface waters. In such a case the state contends, SWRCB
Resolution 92-49 requires remediation of the vadose zone to the lowest concentration levels of
constituents technically and economically feasible, which must at least protect the beneficial
uses of groundwater and surface waters, but need not be more stringent than is necessary to
achieve background levels of the constituents in surface water and groundwater.
Many of the requirements for the proper handling and disposal of designated waste (23 CCR,
Division 3, Chapter 15) have been incorporated through the use of the on-base ex situ
bioremediation facility. This facility will first handle RCRA and/or designated waste from
petroleum-only contaminated sites. These sites are, by definition, excluded from CERCLA
but included within the Defense Environmental Restoration Program conducted pursuant to 10
U.S. Code Section 2701 et. seq. These provisions require that Defense Environmental
Restoration Program response actions be conducted consistent with CERCLA Section 120 and
guidelines, rules, and regulations (e.g., NCP), and criteria established by the USEPA. The
RL/IO-95/ES/1260005.AWS
6-37
-------
"petroleum only" contaminated sites were included in the RI, FFS, and Proposed Plan in a
manner consistent with the Federal Facility Agreement and Defense Environmental Restoration
Program. The SRWCB identified Waste Discharge Requirements (WDRs) for the operation of
the ex situ bioremediation site due to the use of the site for treatment of contaminated media
from the petroleum-only contaminated sites. Substantive WDRs have been developed in order
to implement the portions of WDRs that are substantive requirements for treating CERCLA
wastes at the ex situ bioremediation facility. Under these circumstances, the WDRs served as,
a means of identifying the Regional Water Quality Control Board's substantive requirements
for the ex situ bioremediation facility. This expedient reference to the WDRs to identify
substantive requirements is not intended to suggest that WDRs or any other form of permit are
requirements for this ROD or any other CERCLA onsite response actions. The substantive
WDRs are listed in Section 6.3.2.5.
6.3.2.3 State Solid Waste ARARs
The California Integrated Waste Management Act of 1989 is intended to reduce, recycle, and
reuse solid waste generated in the state to the maximum extent feasible in an efficient and
cost-effective manner to conserve water, energy, and other natural resources, to protect the
environment, and to improve the regulations for solid waste management. Sections of the
Public Resource Code which were used as a source for action-specific ARARs are presented in
Table 6-6, along with the associated regulatory citations.
California Title 14: Natural Resources. Division 7, Integrated Waste Management Board;
Chapter 3 - Minimum Standards for Solid Waste Management Handling and Disposal,
Article 7.8 - Disposal Site Closure and Post-Closure Maintenance. Table 6-6 contains the
applicable or relevant and appropriate sections of these regulations identifying the ARAR
status and a brief description of the substantive requirements and applicability to either the
sites, remedial action, or technology used to cleanup the site and contaminated material.
The requirements in 14 CCR 17788, ("the landfill is to be maintained and monitored for a
period of not less than 30 years after completion of closure pursuant to Chapter 5, Article 3.4,
Section 18265") will be applied with consideration.to the facts that Site 7:
• has been dormant and inactive for approximately 30 years;
• was closed in accordance with requirements in effect at the time; and
• currently poses no threat to human health and the environment.
RL/10-95/ES/1260005.AWS
6-38
-------
The requirements of 14 CCR 17788 will be met as described in the following manner.
The USAF will cap, if appropriate, the impacted area in accordance with all ARARs listed in
Table 6-6. After the cap is in place the USAF will maintain and monitor the cap in
accordance with 14 CCR 17788(a)(l - 5) as long as the site presents an unacceptable risk to
human health and the environment. 14 CCR 17796(c) requires that any construction
improvements on the landfill sites will maintain the integrity and functioning of the landfill
containment and monitoring system, and that any new activities at the site will not increase the
potential threat to health, safety, and the environment.
6.3.2.4 Other State Regulations
The State Fish and Game Code regulates to protect aquatic life living in the waters of the state.
All remedial activities that have the potential of causing a discharge to any stream lake or
other body of water must comply with the requirements of the code.
Regional Water Quality Control Board, CVR Basin Plan "Disposal of Wastewater on Land
Policy." This plan is a TBC to any activity that may affect water quality. The Basin Plan
requires that land disposal be considered an alternative to discharges to surface waters.
Tri-Regional Board Staff Recommendations for Preliminary Evaluation and Investigation of
Underground Tank Sites - this action-specific TBC recommends that soil samples from UST
sites be analyzed for total petroleum hydrocarbon (TPH) as gasoline or diesel (depending upon
the fuel) and BTEX. The appendix to this guideline recommends that a final remedial plan
include a verification sampling program.
California Well Standards (California Department of Water Resources [DWR], Bulletin 74-90,
June 1991) and Sacramento County Code, Title 6, Chapter 6.28 - The California Water Code
(Chapters 1152, 1373, and 13801) requires the DWR to establish standards for the
construction, operation, and abandonment of water wells, monitoring wells, and cathodic
protection wells. Sacramento County has developed well construction regulations based on
authority granted to the county through enforcement of the state standards. These standards
should be considered as TBCs for construction of groundwater wells (injection, extraction, and
monitoring).
In addition to these well standards, the guidelines provided by the California Base Closure.
Environmental Committee (March 1994) in "Long-Term Groundwater Monitoring Guidance"
are TBCs for:
RL/10-95/ES/1260005.AWS
6-39
-------
• establishing background ground water quality;
• frequency of water level measurements;
• suite of constituents in the monitoring program;
• sampling frequency; and
• inspection and well maintenance.
Several of the California regulations require certification by a professional geologist or
engineer, registered or certified by the State of California. These portions of the regulations
are considered procedural rather than substantive requirements. However, to the degree that
federal contractors perform and/or supervise the engineering and geotechnical work, they will
be certified professional or under the supervision of certified professionals as appropriate.
6.3.2.5 State Requirements for Ex Situ Soil Bioremediation Facility
As discussed in Section 2.2.9 of this document, the USAF will operate an ex situ soil
bioremediation facility onsite to treat excavated soils from Sites 56, 59, 60, 62, and 65, and
other suitable sites with CERCLA contamination. Approximately 5,000 yd3 of soil from these
sites are expected to be treated at the bioremediation facility. The USAF also expects to use
the ex situ soil bioremediation facility for the treatment of petroleum-contaminated soils
excavated from sites described in Section 4.0 that are not being addressed under the CERCLA
process. Use of the bioremediation facility for the Section 4.0 sites is hereafter referred to as
"Phase I operation" since this soil treatment is expected to occur prior to treatment of soils
excavated from the CERCLA sites.
The bioremediation facility will consist of a single lined bioremediation cell and soil
processing area. During operation of the facility during Phase I, the USAF will comply with
the WDRs specified in CVRWQCB Order No. 95-221. The WDRs were derived from
Title 23 CCR, Division 3, Chapter 15.
Operation of the bioremediation facility for CERCLA-related response actions (e.g., treatment
and disposal of treated soils from the sites discussed in Section 2.2.9), the USAF will comply
with the intent of the substantive requirements for Class II Waste Piles found in or derived
from Chapter 15. Substantive requirements for this particular soil bioremediation facility and
optional conditions the USAF agrees to comply with, include the following:
• The design of the bioremediation cell unit will consist of the following
components from top to bottom: four to six inch cover, consisting of least
RL/10-95/ES/1260005.AWS 6-40
-------
contaminated soil; six inch sand layer, or a three inch sand layer and
three inches of recycled drainage rock; geotextile fabric; 30 mil PVC liner;
geotextile fabric over a mostly asphalt base with some areas of native soil.
Materials used to construct liners will have appropriate physical and chemical
properties to ensure containment of discharged wastes over the operating life
and closure of the bioremediation cell. All visible portions of synthetic liners
will be inspected on a weekly basis.
Materials used to construct leachate collection and removal systems (LCRSs)
will have appropriate physical and chemical properties to ensure the
transmission of leachate over the life of the bioremediation cell and the closure
period. Leachate collection and removal systems will be designed, constructed,
and maintained to collect twice the anticipated daily volume of leachate
generated by the unit and to prevent buildup of hydraulic head on the
underlying liner or underlying natural geologic materials of low hydraulic
conductivity at any time. The depth of fluid in any LCRS sump will be kept at
the minimum necessary for safe pump operation. The LCRS sump will be
inspected three tunes per week for leachate generation.
The bioremediation facility will be designed, constructed, and operated to
prevent inundation or washout due to 100-year floods. The waste containment
facilities and precipitation and drainage controls will be properly maintained
until clean closure has been achieved.
Waste destined for treatment will only be discharged into, and shall be confined
to, the soil processing area, the bioremediation cell, or tanks specifically
designed for waste containment.
All wells within 500 feet of the unit will have sanitary seals meeting the
requirements of the Sacramento County Environmental Health Management
Department or will be properly abandoned.
Accept only soils that are not classified as "hazardous waste" using the criteria
in Title 22 CCR, Division 4.5, Chapter 11, for discharge to the bioremediation
facility, subject to variances from hazardous waste management requirements
established by the DTSC. Additionally, wastes that could potentially impair the
integrity of containment structures, require a higher level of containment than
provided by the unit, or which are restricted hazardous wastes will not be
discharged to the bioremediation facility.
Other than the minimum amount of water necessary for dust control and
operation of the bioremediation process, the USAF will not discharge liquid,
semi-solid waste (waste containing less than 50 percent solids), or solid waste
containing free liquid or moisture in excess of the waste's moisture holding
capacity to the bioremediation cell.
RL/IO-95/ES/1260005.AWS 641
-------
The discharge of designated solid or liquid waste or leachate to surface water,
surface water drainage courses, ponded water, or ground water that would cause
impairment to water quality is prohibited.
Leachate and runoff from the bioremediation cell will flow into a sump where it
will be pumped to a Baker tank. From storage in the Baker tank, the liquid will
be used to supplement the moisture content soils that do not have sufficient
moisture to support the bioremediation process.
Waste or waste constituents from the bioremediation facility will not be
discharged to natural geologic materials, groundwater, or surface waters at,
beneath, or adjacent to the waste management units. This includes ponded
water and areas within 100 feet of surface waters.
Treated soils may be disposed of as "inert waste" if the following criteria are
met:
the treated soil is not a hazardous waste as determined by criteria in
22 CCR Division 4, Chapter 11, including toxicity, ignitability,
reactivity, and corrosivity;
TPH as gasoline and aromatic volatile organics (BTEX) are not
detectable in representative samples of treated soil;
the leachable TPH as diesel concentration is less than 10 ug/L;
the metal concentrations are less than the 95 percent UCL of the
background concentration calculated in the "Background Inorganic Soils
Report for Mather AFB" [IT 1993f]; and
PAHs will not be discharged where they will be subject to erosion and
transport to surface waters.
Soil taken from the bioremediation facility and used as foundation material at
Landfill Sites 3 and 4 will have total or leachable constituent concentrations
equal to or less than those presented in Table 6-8. Soil not achieving these
levels will be disposed at an offsite Class II Waste Disposal Facility or treated
and disposed in an appropriate manner.
RL/10-95/ES/I260005.AWS
6-42
-------
Table 6-8. Maximum Total or Leachable Constituent Concentrations
Constituent
Concentration
TPH-D
TPH-G
Oil and Grease
Aromatic Hydrocarbons
Benzene
Ethylbenzene
Toluene
Xylene
Img/L
Median Concentration is non-detect
Maximum Concentration is 5 mg/kg
430 mg/kg
Median Concentration is non-detect
Maximum Concentration is 0.01 mg/kg
Median Concentration is non-detect
Maximum Concentration is 0.29 mg/kg
Median Concentration is non-detect
Maximum Concentration is 0.42 mg/kg
Median Concentration is non-detect
Maximum Concentration is 0.17 mg/kg
Polycyclic Aromatic Hydrocarbons
Benzo(a)Anthracene
Benzo(a)Pyrene
Benzo(b)Fluoranthene
Benzo(k)Fluoranthene
Chrysene
0.01 mg/L
0.02 mg/L
0.02 mg/L
0.02 mg/L
0.02 mg/L
Toxic Metals
Lead
Organic Lead
Manganese
Chromium
1.5 mg/L
0.5 mg/kg
0.5 mg/L
0.5 mg/L
TPH-D = total petroleum hydrocarbon as diesel
TPH-G = total petroleum hydrocarbon as gasoline
mg/kg = milligrams per kilogram
mg/L = milligrams per liter
If soil is not inert, and for discharge to a location other than Landfill Site 3
or 4, the following cleanup levels prior to removal of treated soils from the
bioremediation cell will be implemented:
Total petroleum hydrocarbon as diesel, nonvolatiles, PAHs, lead, and/or
other metals will not be present in representative samples of treated soil
in soluble concentrations that will impact either surface or groundwater
as determined by the DLM or an appropriate fate and transport
predictive model. Soluble concentrations will be measured using the
deionized water (DI) WET Method.
RL/IO-95/ES/1260005.AWS
6-43
-------
Aromatic volatile organic compounds will not be detectable using
analytical detection limits as close to USEPA Method Detection Limits
as practicable.
The bioremediation facility will be clean-closed after completion of use in
accordance with the closure plan. At closure, all residual wastes, including
liquids, sludge, precipitates, settled solids, and liner materials and adjacent
natural geologic materials contaminated by wastes will be completely removed
and discharged to an appropriate waste management unit.
RL/10-95/ES/I260005.AWS
6-44
-------
7.0 Responsiveness Summary
The public comment period for the "Proposed Plan for the Groundwater Operable Unit Plumes
and Soil Operable Unit Sites" [IT 1995b] at Mather AFB, began on May 8, 1995 and ended on
June 7, 1995. A public meeting was held on May 18, 1995, at which the Proposed Plan was
summarized, and questions and public comments solicited. The transcript from the public
meeting is included in the Administrative Record File and reproduced here. The public
submitted four formal written comments on the Proposed Plan. The written comments were
from the USEPA and County of Sacramento and are included in the Administrative Record.
No other comments were received during the public comment period.
Note: Sites 19, 29/B, 32, 34, 35, and 36 are sites with only petroleum contamination and are
excluded from regulation under CERCLA. The USAF is not responding to comments on these
sites in this ROD. Public comments on "petroleum only" sites will be considered by the
CVRWQCB in approving cleanup activities at these sites.
Comment 1 and Response:
Comment:
The County is very concerned that inadequate cleanup budget, including possible
cutbacks, will seriously delay environmental investigation and cleanup and in turn
seriously impact productive economic reuse of the base property. The USAF must
proceed diligently to assure funding for environmental cleanup and compliance within
the time frames necessary for reuse. The work described in the Proposed Plan must
proceed on a timely basis, or successful reuse may be jeopardized.
Response:
The USAF has and will continue to seek adequate funding for cleanup at Mather AFB
for the protection of human health and the environment, and to support base reuse
objectives to the best of the USAF's resources and ability consistent with USAF policy.
Presently, all identified remediation requirements at Mather AFB are scheduled to
receive sufficient funding necessary to implement planned remedial response actions in
accordance with the ROD for the Soil OU sites and Groundwater OU plumes.
RL/10-95/ES/1260005.AWS '"*
-------
Comment 2 and Response:
Comment:
Particularly, funding should be prioritized for high priority reuse projects identified
by the County. An initial list of such high priority County projects has previously
been distributed and discussed with the USAF and environmental regulators. This list
is attached to this letter as Exhibit A.
Response:
The USAF has reviewed the list of high priority County projects, and in the future
will consider the County reuse priorities during project planning and funding
prioritization. It is USAF policy to give funding priority to projects that promote
rescue, after human health concerns and regulatory compliance requirements have
been addressed. However, with the expectation of the County Department of Public
Works Roadway Improvement and Relocation Program, the projects identified on the
County Priority List have no association with any of the remedial actions proposed in
this Soil OU sites and Groundwater OU plumes ROD. The Roadway Improvement
and Relocation Program proposes new road construction, road realignments, and road
widening which may conflict or interfere with planned remedial actions. The USAF
is working with County officials to coordinate compatible remedial actions. In some
instances road realignment may need to be delayed until remedial actions have been
concluded. In other instances remedial actions may be designed and scheduled to
allow work on roads to proceed in a timely manner.
Comment 3 and Response:
Comment:
The County is currently initiating several development projects, including demolition
of existing structures, construction of new structures, utility line reallocations, and
roadway improvements and relocation. New areas of contamination may be
discovered as part of the County's reuse efforts. In large part due to budget issues,
the County and USAF must investigate entering into a memorandum of understanding
or similar arrangement, whereby the County could assist the USAF in performing site
investigations/assessments and minor cleanups, to be reimbursed by the USAF. Such
a relationship should be discussed and included in the Proposed Plan, and the County
and USAF should continue to explore this possibility.
RiyiO-95/ES/1260005.AWS 7-2
-------
Response:
The comment proposes using a memorandum of understanding that would allow
Sacramento County to assist in investigating and performing minor cleanups at newly
discovered areas of contamination. The comment does not address itself to any of the
proposed remedial alternatives in the Proposed Plan. This comment is being
discussed directly with Sacramento County.
RL/10-9S/ES/1260005.AWS 7-3
-------
-------
8.0 References
Aerovironment, Inc., 1987, "Installation Restoration Program Phase II -
Confirmation/Quantification Stage 2 Final Report, September 1985 to June 1987," Volumes 1
and 2, Aerovironment, Inc., Monrovia, California.
Aerovironment, Inc., 1988, "Installation Restoration Program Phase II -
Confirmation/Quantification Stage 3 Final Report, July 1986 to March 1987," Volumes 1
and 2, Aerovironment, Inc., Monrovia, California.
California State Water Resources Control Board (SWRCB), 1992, "California State Water
Resources Control Board ARARs Under CERCLA," Sacramento, California.
CH2M-HU1, Inc., 1982, "Installation Restoration Program Records Search (Phase 1),"
CH2M-Hill, Inc., Gainesville, Florida.
Central Valley Regional Water Quality Control Board (CVRWQCB), 1989, "The Designated
Level Methodology for Waste Characterization and Cleanup Level Determination," California
Regional Water Quality Control Board, Central Valley Region Staff Report, October 1986
(updated June 1989).
Central Valley Regional Water Quality Control Board (CVRWQCB), 1993, "A Compilation of
Water Quality Goals," Central Valley Regional Water Quality Control Board, Sacramento,
California.
Central Valley Regional Water Quality Control Board (CVRWQCB), 1995, "Basin Plan for
Sacramento-San Joaquin Basin," California Regional Water Quality Control Board,
Sacramento, California.
EA Engineering, Science, and Technology (EA), 1990a, "Quarterly Groundwater Sampling at
Mather Air Force Base, May-June 1990," Volume 1-Report; Volume 2-Appendix A,
Appendix B, Appendix C, Pt. 1; Volume 3-Appendix C, Pt. 2; EA Engineering, Science, and
Technology Corporation, Lafayette, California.
RL/IO-95/ES/1260005.AWS
8-1
-------
EA Engineering, Science, and Technology (EA), 1990b, "Quarterly Groundwater Sampling at
Mather Air Force Base, August 1990," Volume 1-Report; Volume 2-Appendix A, Appendix
B, Appendix C, Pt. 1; Volume 3-Appendix C, Pt. 2; EA Engineering, Science, and
Technology Corporation, Lafayette, California.
EA Engineering, Science, and Technology (EA), 1990c, "Quarterly Groundwater Sampling at
Mather Air Force Base, November-December 1990," Volume 1-Report; Volume 2-Appendix
A, Appendix B, Appendix C, Pt. 1; Volume 3-Appendix C, Pt. 2; EA Engineering, Science,
and Technology Corporation, Lafayette, California.
IT Corporation (IT), 1988a, "Well Redevelopment and Sampling Plan for Mather Air Force
Base, California," Prepared by IT Corporation for HAZWRAP, July 1988.
IT Corporation (IT), 1988b, "U.S. Air Force Installation Restoration Program, Phase IV-A
Activities at Mather Air Force Base, California, Landfill Gas Testing Report for Eight Sites at
Mather Air Force Base, California", Prepared by IT Corporation for Hazardous Waste
Remedial Actions Program.
IT Corporation (IT), 1990a, "U.S. Air Force Installation Restoration Program, Phase IV-A
Activities at Mather Air Force Base, California, Final Site Inspection Report", IT
Corporation, Knoxville, Tennessee.
IT Corporation (IT), 1990b, "Underground Storage Tank Closure Report, Mather Air Force
Base, California".
IT Corporation (IT), 1992a, "Final Remedial Investigation for Group 2 Sites, Mather Air
Force Base, California", Prepared by IT Corporation for Environmental Management
Operations.
IT Corporation (IT), 1993a, "U.S. Air Force Installation Restoration Program, Final
Technical Memorandum for Group 3 Sites for Mather Air Force Base, California", Prepared
by IT Corporation for Environmental Management Operations.
RL/10-95/ES/1260005.AWS
8-2
-------
IT Corporation (IT), 1993b, "U.S. Air Force Installation Restoration Program, Final Solid
Waste Assessment Test Report for Mather Air Force Base, California", Prepared by IT
Corporation for Environmental Management Operations.
IT Corporation (IT), 1993c, Subsurface Soil Investigation (Project C) Underground Storage
Tank Removal Project, Mather Air Force Base, California, Prepared by IT Corporation for
U.S. Corps of Engineers.
IT Corporation (IT), 1993d, Closure Reports, Underground Storage Tank Removal Project,
Mather Air Force Base, California, Prepared by IT Corporation for U.S. Corps of Engineers.
IT Corporation (IT), 1993e, "Superfund Record of Decision: Aircraft Control and Warning
Site, Mather Air Force Base, Sacramento County, California", December 1993, Prepared by
IT Corporation for Environmental Management Operations.
IT Corporation (IT), 1993f, "Background Inorganic Soils for Mather Air Force Base,"
IT Corporation, Albuquerque, New Mexico and Richland, Washington.
IT Corporation (IT), 1993g, "Quarterly Groundwater Monitoring Report - Third Quarter 1993
for Mather Air Force Base, California," IT Corporation, Martinez, California.
IT Corporation (IT), 1994a, "Final Soils and Groundwater Operable Unit Additional Field
Investigation Remedial Investigation Report for Mather Air Force Base, California," Prepared
by IT Corporation for Air Force Center for Environmental Excellence, Brooks Air Force
Base, Texas.
IT Corporation (IT), 1994b, "Superfund Draft Final Record of Decision, Landfill Operable
Unit Sites, Mather Air Force Base, Sacramento County California," Prepared by IT
Corporation for Air Force Center for Environmental Excellence, Brooks Air Force Base,
Texas, December 12, 1994.
IT Corporation (IT), 1994c, "Removal Action Memorandum for Sites 20, 29, and 32, Mather
Air Force Base, California," Prepared by IT Corporation for Battelle Environmental Services
Organization, September, 1994.
RL/10-95/ES/1260005.AWS
-------
IT Corporation (IT), 1995a, "Groundwater Operable Unit and Soil Operable Unit Focused
Feasibility Study Report for Mather Air Force Base, California," Prepared by IT Corporation
for Air Force Center for Environmental Excellence, Brooks Air Force Base, Texas.
IT Corporation (IT), 1995b, "Proposed Plan for Environmental Cleanup at the Groundwater
Operable Unit Plumes and Soil Operable Unit Sites," Prepared by IT Corporation for U.S. Air
Force Base Conversion Agency, Mather Air Force Base, California.
IT Corporation (IT), 1995c, "Quarterly Monitoring Report - Third Quarter 1995 for Mather
Air Force Base, California," IT Corporation, Martinez, California.
IT Corporation (IT), 1995d, "Final Mather Baseline Risk Assessment (MBRA) Mather Air
Force Base, California," Prepared by IT Corporation for Air Force Center for Environmental
Excellence, Brooks Air Force Base, Texas, December 19, 1995.
IT Corporation, 1996a, "Draft Technical Information Report on Soil Vapro Extraction Pilot
Testing at Installation Restoration Program Sites 18, 39, and 57, " Prepared by IT Corporation
for Air Force Center for Environmental Excellence, Brooks Air Force Base, Texas, March 12,
1996.
IT Corporation, 1996b, "Draft Additional Site Characterization and Final Basewinde Operable
Unit Remedail Investigation Report," Prepared by IT Corporation for Air Force Center for
Environmental Excellence, Brooks Air Force Base, Texas, March 19, 1996.
U.S. Environmental Protection Agency (USEPA), 1987, "Data Quality Objectives for
Remedial Response Activities: Development Process, March 1987," EPA/540/G-87/003,
Washington, D.C.
U.S. Environmental Protection Agency (USEPA), 1988, "CERCLA Compliance with Other
Laws Manual, Part I: Interim Final, August 1988," EPA/540/G-89/006, Washington, D.C.
U.S. Environmental Protection Agency (USEPA), 1989a, "Risk Assessment Guidance for
Superfund, Volume I, Human Health Evaluation Manual, Interim Final, December, 1989,"
EPA/540/1-89/002, Washington, D.C.
8 4
RL/10-95/ES/1260005.AWS °"^
-------
U.S. Environmental Protection Agency (USEPA), 1989b, "CERCLA Compliance with Other
Laws Manual, Part II: Clean Air Act and Other Environmental Statues and State
Requirements," EPA/540/G-89/009, Washington, D.C., August 1989.
Weston, Roy F., Inc. (Weston), 1986, "Installation Restoration Program Phase n -
Confirmation/Quantification Stage 1 Final Report," Volumes 1 and 2, Roy F. Weston, Inc.,
West Chester.
RL/10-95/ES/1260005.AWS
8-5
-------
-------
-------
------- |