PB99-964502
EPA541-R99-042
1999
EPA Superfund
Record of Decision:
Travis Air Force Base
West/Annexes/Basewide OU (WABOU)
Solano County, CA
3/16/1999
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INSTALLATION RESTORATION PROGRAM
West/Annexes/Basewide Operable Unit
Travis Air Force Base
GROUNDWATER INTERIM
RECORD OF DECISION
FORTHEWABOU
FINAL
60th Air Mobility Wing
Travis Air Force Base, California
2808..04
24 JUNE 1999
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SFIM) RECORDS CTR
50825
DEPARTMENT OF THE AIR FORCE
60TH AIR MOBILITY WING (AMC)
24 June 1999
h
MEMORANDUM FOR DISTRIBUTION
FROM: 60AMW/EMR
580 Hickam Avenue
Travis AFB CA 94535-2176
SUBJECT: Final West/Annexes/Basewide Operable Unit (WABOU) Groundwater
Interim Record of Decision (IROD)
1 The attached package provides the change pages needed to convert the draft final
WABOU Groundwater IROD into a final version. This IROD presents the Air
Force's selected alternatives for the mt^m/^^iati^f°^^?:arties M
ornundwater sites We are sending a complete copy of the IROD to all parties tnat
Sd^elve rdraft final version. We are also sending to all parties the response
to EPA comments on the draft final WABOU Groundwater IROD as a separate
attachment.
2. If you have any questions concerning the subject document, please contact Mr.
Glenn Anderson at (707) 424-4359.
ALLEti L. BRICKEEN, P.E.
Remedial Program Manager
Attachment:
ttacmen: , ,
Final WABOU Groundwater IROD (package or complete copy)
Response to EPA comments on the draft final WABOU Groundwater IROD
Distribution: (See attached)
AMC - - GLOBAL REACH FOR AMERICA
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.
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Copy No. 27
Recipient John Lucey
Agency U.S. EPA
West/Annexes/Basewide Operable Unit
Travis Air Force Base
Groundwater Interim
Record of Decision for the WABOU
Final
60th Air Mobility Wing
Travis Air Force Base, California
24 June 1999
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Contents __
Page
Section
vi
Acronyms List *
, 1
Parti Declaration • 1
Site Name and Location •
Statement of Basis and Purpose : ^
Assessment of the Site ^
Rationale for Interim Grqundwater ROD
Description of the Selected Interim Remedies •
Declaration
9
Part II Decision Summary - 9
1.0 Travis AFB Description - •""•
1.1 Physical Description • • '
1.2 Land Use • ^
1.3 Ecology
1.4 Geology and Hydrogeology
1.5 Surface Water • ~~
2.0 Overview of Travis AFB Environmental Programs &
2.1 Compliance Branch
2.2 Restoration Branch :
2.3 Pollution Prevention Branch ^
3.0 WABOU Groundwater Remedial Investigation Summary ^1
3.1 Nature and Extent of Contamination 31
3.2 Risk Assessments
3.3 Chemicals of Concern ^
3.4 Summary - _
4.0 Summary of WABOU Groundwater Feasibility Study ^
4.1 Initial Screening of Alternatives 3/
4.2 Detailed Analysis of Alternatives f**
4.3 Comparative Analysis of Alternatives 3*
4.4 Conclusion ;
5 0 Interim Groundwater Remedial Actions ^5
5.1 Building 755 (DP039) J°
5.2 Landfill 3 (LF008) *(
5.3 Buildings 905 (SS041) and 916 (SD043) g
5.4 Treatment ^
5.5 Treated Water Disposal ~
5.6 Land Use Restrictions j~
5.7 Groundwater Monitoring • ^
5.8 Statutory Determinations - ^
5.9 RD/RA Implementation and Schedule =/
5.10 Documentation of Significant Changes 58
BDD-SFO/960970009.DCXD (LNB213.00C)
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Contents, Continued
Page
Section
6.0 List of Applicable or Relevant and Appropriate ^"" 59
Performance Standards " ^
6.2 AKA^WmtificatioZDevelopment, and Evaluation 60
6.3 Determination of ARARs 61
6.4 ARARs Evaluation and Discussion »• • ^
7.0 Works Cited ;
90
Part III Responsiveness Summary —.—•
Appendix A: Site Summary Figures
RDD-SFO/980970009.DOC (LN8213.DOC)
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Contents, Continued
Page
Tables
1 Potential Interim Groundwater Remedial Alternatives
2 Selected Interim Groundwater Remedial Actions -
1-1 Stratigraphic Column of Geologic Units at Travis AFB 16
1-2 Summary of Hydraulic Conductivity Values Derived from Aquifer Tests ^
Conducted at Travis AFB
3-1 COC Concentrations and Potential Risks at WABOU Groundwater Sites 35
4-1 Interim Groundwater Remedial Alternatives
4-2 SummaryofComparativeAnalysisofGroundwaterAlternatives-byCriterion ^
Long-term Effectiveness and Permanence
4.3 SummaryofComparativeAr^lysiSofGroundwaterAltematives-byCriterion
Reduction of Toxiciry, Mobility, and Volume through Treatment 42
4-4 Summary of Comparative Analysis of Groundwater Alternatives - by Criterion ^
Short-Term Effectiveness
4-5 Summary of Comparative Analysis of Groundwater Alteratives - by^terion ^
Implementabiliry
4-6 Cost Estimates for WABOU Groundwater Remedial Alternatives 45
5-1 Interim Cleanup Goals for Groundwater COCs
6-1 Travis AFB-WABOU Groundwater Sites, Federal ARARs, Waste Transfer,
Treatment, and Storage and Disposal Requirements
6-2 Travis AFB-WABOU Groundwater Sites, State ARARs, Air Remediation ^
Requirements •
6-3 Travis AFB-WABOU Groundwater Sites, State ARARs, WateBoarf ^
Requirements
6-4 Travis AFB-WABOU Groundwater Sites, Federal ARARs, Requirements under the^
US Code and Related Regulations
6-5 Travis AFB-WABOU Groundwater Sites, State ARARs, Fish and.Game ^
Requirements
6-6 NPDES Effluent Limitations for Treated Groundwater M
86
6-7 Discharge Limitations
RDD-SFO/980970009.DOC (LN6213.DOC)
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Contents, Continued
Page
Tables, Continued
6-8 Effluent Treatment Levels for Beneficial Reuse, Discharges to Land for brighten ^
Purposes
Figures
1-1 Travis AFB/Annex Location Map • '
1-2 Geologic Map of Travis AFB and Vicinity
19
1-3 Groundwater Contour Map, July 9,1996
3-1 WABOU Groundwater Sites and Extent of Groundwater Contamination 32
40
4-1 Nine Evaluation Criteria
5-1 Alternative G5 - Source Area and Groundwater Extraction/Treatment/
Monitored Natural Attenuation, Conceptual Design at Building 755 :....«
5-2 Alternative G3 - Containment/Treatment/Discharge, Conceptual Design at ^
Building 755
5-3 Alternative G4-Extraction/Treatment/Discharge, Conceptual Design at ^
Landfills
5-4 Alternative G3 - Containment/Treatment/Discharge, Conceptual Design at ^
Buildings 905/916
RDD-SFO/980970009.DOC (LNB213.DOC)
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Acronyms List
AFB
AFCEE
AMC
AMW
ARARs
BAAQMD
Base
bgs
CAL-EPA/DTSC
CERCLA
CFGC
COC
COEC
COPC
CRP
DAA
DCA
DCE
DNAPL
DPE
EIOU
FFA
fpm
FS
gpm
GSAP
Air Force Base
Air Force Center for Environmental Excellence
Air Mobility Command
Air Mobility Wing
Applicable or Relevant and Appropriate Requirements
Bay Area Air Quality Management District
Air Force Base
below ground surface
California Environmental Protection Agency/Department of
Toxic Substances Control
Comprehensive Environmental Response, Compensation,
and Liability Act of 1980
California Fish and Game Code
chemical of concern
chemical of ecological concern
chemical of potential concern
Community Relations Plan
Detailed Analysis of Alternatives
dichloroethane
dichloroethene
dense non-aqueous phase liquid
Dual-Phase Extraction
East Industrial Operable Unit
Federal Facility Agreement
feet per minute
Feasibility Study
gallons per minute
Groundwater Sampling and Analysis Program
RDD-SFO/980970009.DOC (LNB213.DOC)
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Acronyms List
HHRA
HI
HWCL
IROD
IRP
ISA
LGAC
MAP
MCL
MNA
msi
NAAP
NCP
NEWIOU
NOU
NPDES
NPL
O&M
OU
P2MAP
PAH
PCB
PCE
PCG
PCWQCA
POCOS
PP
ppb
ppt
Human Health Risk Assessment
Hazard Index
California Hazardous Waste Control Law
Interim Record of Decision
Installation Restoration Program
Initial Screening of Alternatives
liquid-phase granular activated carbon
micrograms per liter
Management Action Plan
maximum contaminant level
Monitored Natural Attenuation
mean sea level
Natural Attenuation Assessment Plan
National Contingency Plan
North/East/West Industrial Operable Unit
North Operable Unit
National Pollution Discharge Elimination System
National Priorities List
operations and maintenance
operable unit
Pollution Prevention Management Action Plan
polyaromatic hydrocarbon
polychlorinated biphenyl
tetrachloroethene
Preliminary Cleanup Goal
Porter-Cologne Water Quality Control Act
Petroleum-only Contaminated Sites
Proposed Plan
parts per billion
parts per trillion
vn
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Acronyms List
PRG
RA
RAB
RAO
RCRA
RD
RD/RA
RI
ROD
RPM
SARA
SFBRWQCB
SIP
SWRCB
TBC
TCA
TCE
TPH-d
TPH-g
U.S. EPA
UST
VGAC
VOC
WABOU
WIOU
Preliminary Remediation Goal
remedial action
Restoration Advisory Board
Remedial Action Objective
Resource Conservation and Recovery Act
remedial design
remedial design/remedial action
Remedial Investigation
Record of Decision
Remedial Project Manager
Superfund Amendments and Reauthorization Act of 1986
San Francisco Bay Regional Water Quality Control Board
State Implementation Plan
State Water Resources Control Board
to be considered
trichloroethane
trichloroethene
total petroleum hydrocarbons-diesel
total petroleum hydrocarbons-gasoline
U.S. Environmental Protection Agency
underground storage tank
vapor-phase granular activated carbon
volatile organic compound
West/Annexes/Basewide Operable Unit
West Industrial Operable Unit
VIII
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PARTI
Declaration
Site Name and Location
Department of the Air Force
Travis Air Force Base
Fairfield, California 94535-5000
Statement of Basis and Purpose
This Interim Record of Decision (IROD) presents the interim groundwater remedial actions
in the West/Armexes/Basewide Operable Unit (WABOU) at the Travas Air Fane Base
(AFB) Superfund site in Solano County, California. The Air Force will develop a separate
WABOU Soil Record of Decision (ROD) to present the soil remedial actions in the WABOU.
The Air Force selected the interim groundwater remedial actions ™.fcco'd?nf™*h **
Comprehensive Environmental Response, Compensation, and Liability Actof 198°
(CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986
SARA) 42 USC § 9601 et sec,., and with the National Oil and Hazardous Substances
Pollution Contingency Plan, 40 CFR Part 300 (National Contingency Plan [NCP]). The
Administrative Record contains the documents used in the selection of the interim
Kroundwater remedial actions. The Administrative Record is available for review at Travis
AFB. The Travis AFB information repository also includes copies of these documents tor
public review and is found in the Vacaville Public Library.
The U.S. Environmental Protection Agency (U.S. EPA), Region DC, concurs with the selected
interim groundwater remedies. The State of California, through the California
Environmental Protection Agency's Department of Toxic Substances Control (Cal-
EPA/DTSC) and the San Francisco Bay Regional Water Quality Control Board
(SFBRWQCB), concurs with the selected interim groundwater remedies.
Assessment of the Site
As a result of past industrial activities, releases of volatile organic compounds (VOCs),
polychlorinated biphenyls (PCBs), and pesticides have contaminated the groundwater at
four WABOU sites at Travis AFB. These sites are Building 755, Landfill 3, Building 905 and
Building 916. Actual or threatened releases of hazardous substances from these sites^ if not
addressed by implementing the response actions selected in this Groundwater IROD, may
present a potential threat to public health, welfare, or the environment.
Rationale for Interim Groundwater ROD
The Air Force has developed interim remedial actions to address groundwater
contamination in the WABOU. The Air Force has prepared this groundwater IROD rather
RDD-SFO/980960020.DOC (INB212.DOC)
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PARTI DECLARATION
than a final groundwater ROD in order to allow groundwater remediation to begin quickly
to reduce contamination and risk. The groundwater IROD establishes an interim period.to
evaluate the effectiveness of the interim groundwater remedial actions and to monitor the
status of each contaminant plume. The Air Force will use this data to establish final cleanup
levels and select technically and economically feasible long-term actions m the final
eroundwater ROD. The Air Force will publish a public notice, hold a public comment
period, and address the public's comments before the regulatory agencies finalize and
approve the groundwater ROD. The Air Force will publish a separate Soil ROD to describe
the soil remedial actions in the WABOU.
Description of the Selected Interim Remedies
The Air Force considered six potential interim remedial alternatives to address
contaminated groundwater in the WABOU. Table 1 presents the potential interim
groundwater remedial alternatives.
TABLE 1
Potential Interim Groundwater Remedial Alternatives
Remedial Alternative
Description
G1 - No Action
G2- Monitored Natural
Attenuation
G3 - Containment/
Treatment/Discharge
G4 - Extraction/
Treatment/Discharge
G5 - Source Area and
Groundwater Extraction/
Treatment/ Monitored Natural
Attenuation
GB - Source Area Extraction/
Treatment/ Monitored Natural
Attenuation
This serves as a starting point for comparing the other alternatives. No
groundwater treatment takes place.
Monitored Natural Attenuation (MNA) is a groundwater treatment strategy that
relies on naturally occurring processes to prevent the spread of contamination. A
major part of this strategy is the destruction of contaminants into harmless
byproducts by subsurface microorganisms. Groundwater monitoring is used to
verify the effectiveness of this strategy.
This alternative is designed to prevent the migration of the groundwater
contamination. Groundwater is pumped from a series of extraction wells that are
built near the leading edge of the contaminant plume. The resulting hydraulic
barrier removes the contaminated groundwater before it can move past the
extraction wells. The removed groundwater is treated using activated carbon and
is either discharged to Union Creek or used for irrigation.
This alternative uses the extraction wells as described in alternative G3. It also
places additional extraction wells in the more highly contaminated part of the
plume in order to actively treat the whole plume. The removed groundwater is
treated and is either discharged to Union Creek or used for irrigation.
This alternative applies only to Building 755 and is divided into three parts. The
first part uses a vacuum-enhanced groundwater technology, known as Dual-
Phase Extraction (DPE). A DPE system uses a vacuum to draw contaminated
groundwater into an extraction well and at the same time lower the local water
table. Exposed pools of solvents would then evaporate, and the vacuum removes
the contaminated vapors. The water and vapors are cleansed in a treatment
plant This is designed to remove the source of contamination at this site. The
second part uses extraction wells in the center of the plume to remove highly
contaminated groundwater. The third part uses MNA to treat the portion of the
plume with lower contaminant concentrations. MNA is described in alternative
G2.
This alternative also applies only to Building 755 and is divided into three parts.
The first part is the DPE system that is described above. The second part uses a
reactive wall in the subsurface to treat the contaminated groundwater as it
passes through the wall. The third part uses MNA technology to treat the portion
of the plume with lower contaminant concentrations. MNA is described in
alternative G2. —
ROD-SFO/980960020.DOC (LN6212.DOC)
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PARTI DECLARATION
The Air Force has selected interim remedial alternatives for the four WABOU sites with
groundwater contamination. Table 2 presents the selected interim groundwater remedial
alternatives.
TABLE 2
Selected Interim Groundwater Remedial Actions
Site Name (Site Designation)
Selected Alternative
Building 755 (DP039)
Landfill 3 (LF008)
Building 905 (SS041)
Building 916 (SD043)
G5 - Source Area and Groundwater Extraction/
Treatment/ Monitored Natural Attenuation, and
G3 - Containrnent/Treatment/Discharge
G4 - Extraction/Treatment/Discharge
G3 - ContainmentfTreatment/Discharge
G3 - Containment/Treatment/Discharge
The Air Force selected the interim remedies as the most appropriate strategies for
containing, monitoring, and treating contaminated groundwater in the WABOU. These
remedies address the potential risks to human health and the environment that could result
from exposure to groundwater by human (e.g., workers and residents) and ecological (e.g.,
aquatic) receptors.
Previously the Air Force created a North/East/West Industrial Operable Unit (NEWIOU)
Groundwater Remedial Design/Remedial Action (RD/RA) Plan to describe the overall
rationale for treatment and discharge of extracted groundwater for all NEWIOU
croundwater sites. It also included the NEWIOU RD/RA schedule and a decision matrix
for selecting the treatment technologies at each NEWIOU site. The Air Force will add an
addendum to this plan to include a detailed description of the treatment and discharge of
extracted groundwater for the WABOU sites. The addendum will also include the WABOU
RD/RA schedule. The Air Force will provide an opportunity for public participation during
the Remedial Design phase.
Previously the Air Force created a Natural Attenuation Assessment Plan (NAAP) to
provide the methodology used to evaluate the potential use of Monitored Natural
Attenuation (MNA) at NEWIOU sites. The Air Force will add an addendum to the NAAP to
include a description of the approach to be used for the evaluation of the MNA component
of Alternative G5 at Building 755.
In addition to the addendum to the NEWIOU Groundwater RD/RA Plan, the Air Force will
perform a pre-design investigation, as necessary, and then prepare a site-specific RD/RA
work plan for each WABOU groundwater site. The purpose of the pre-design investigation
is to fill existing data gaps so that the Air Force can successfully implement the remedial
action at a site. Examples of data gaps may include the distribution of groundwater
contamination in subsurface strata, hydrogeologic conditions that affect remedial action
performance, and unusual groundwater analytical results that may indicate the presence of
additional groundwater contamination sources. The site-specific RD/RA work plan will
present the results of the site-specific pre-design investigation, the preliminary design
information including the potential placement of extraction and monitoring wells,
groundwater monitoring protocols and frequency, and procedures to determine whether
plume migration is occurring. After regulatory approval of the site-specific RD/RA work
RDD^FQ/980960020.DOC (LNB212.DOC)
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PART I DECLARATION
plan, the Air Force will submit the RD design package that includes drawings,
specifications, and a design report. The site-specific RD/RA work plan and the RD design
package are primary documents and are described in the final NEWIOU Interim
Groundwater RD/RA Plan. If a contingency action is necessary to control migration, the Air
Force will request funding and implement a contingency action as soon as funding becomes
available.
No potential for contaminated groundwater to migrate along storm and sanitary sewer
lines is indicated by a comparison of the highest measured level of the local water table
with the location and depth of the local sanitary and storm sewer lines in the WABOU.
However if future data collection suggests that contaminated groundwater has migrated to
an area where interaction with preferential pathways is likely, the Air Force will investigate
the potential interaction during the Remedial Design (RD). If the RD investigation reveals
an interaction between groundwater and a preferential pathway, then an appropriate
remedial action will be proposed for the site and documented in an amendment to this
Groundwater IROD
The Air Force will implement interim groundwater remedial actions as described in this
WABOU Groundwater IROD. The Air Force will monitor all sites and will measure the
change in contaminant concentrations. The Air Force will utilize the monitoring results to
evaluate the potential for using the MNA component of Alternative G5 at Building 755. The
Air Force and regulatory agencies will periodically review the analytical and performance
data from these actions to verify their effectiveness and the need for additional action(s).
The Air Force and regulatory agencies will hold a formal program review after the IROD is
signed and after sufficient analytical and performance data has been collected. The purpose
of the program review will be to determine the final basewide remedial actions and cleanup
levels that are technically and economically feasible for each groundwater site at Travis
AFB.
Travis AFB will eventually replace this interim ROD with a final ROD as soon as sufficient
data has been collected to support the selection of a final remedy. The sites described in the
final NEWIOU Groundwater IROD and the WABOU groundwater sites may be addressed
in one basewide groundwater ROD if the Travis AFB Cleanup Team decides that this
approach is appropriate.
Declaration
These interim groundwater remedial actions are protective of human health and the
environment are compliant with Federal and State Applicable or Relevant and Appropriate
Requirements (ARARs) directly associated with these actions, and are cost-effective. These
actions utilize permanent solutions and alternative treatment (or resource recovery)
technologies to the maximum extent practicable given the limited scope of the action. These
actions do not constitute the final groundwater remedies for the Travis AFB WABOU sites.
The Air Force and the regulatory agencies will address the statutory preference for
remedies that reduce toxicity, mobility, or volume as a principal element at the time of the
final basewide groundwater ROD. The Air Force will base subsequent actions on the
knowledge and experience gained during the interim actions. Any future actions will fully
address the principal threats posed by contaminated groundwater in the WABOU at Travis
AFB.
RDD-SFOS80960020.DOC (UC212.DOC)
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PART I DECLARATION
Lead and Support Agency Acceptance
of the Interim Groundwater Record of Decision for
the WABOU, Travis Air Force Base
This signature sheet documents agreement between the United States Air Force and the
United States Environmental Protection Agency and the State of California, by the
California Environmental Protection Agency, Department of Toxic Substances Control, and
the San Francisco Bay Regional Water Quality Control Board on the Interim Groundwater
Record of Decision for the WABOU at Travis Air Force Base. The respective parties may
sign this sheet in counterparts.
t
Daniel D.Opalski />
Chief
Federal Facilities Cleanup Branch
U.S. Environmental Protection Agency, Region DC
Anthony J. Landis, P.E. Date
California Environmental Protection Agency
Department of Toxic Substances Control
Chief of Operations
Office of Military Facilities
Loretta K. Barsamian Date
San Francisco Bay Regional Water Quality Control Board
Executive Officer
Walter S.Hogle, Jr. Date
Lieutenant General, USAF
Air Mobility Command
Chairperson, Environmental Protection Committee
RDD-SFO/980960020.DOC (LNB212.00C)
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PART I DECLARATION
Lead and Support Agency Acceptance
of the Interim Groundwater Record of Decision for
the WABOU. Travis Air Force Base
This signature sheet documents agreement between the United States Air Force and the
United States Environmental Protection Agency and the State of California, by the
California Environmental Protection Agency, Department of Toxic Substances Control, and
the San Francisco Bay Regional Water Quality Control Board on the Interim Groundwater
Record of Decision for the WABOU at Travis Air Force Base. The respective parties may
sign this sheet in counterparts.
Daniel D. Opalski Date
Chief
Federal Facilities Cleanup Branch
U.S. Environmental Protection Agency, Region DC
-n
Anthony J. Landis, P.E. Date
California Environmental Protection Agency
Department of Toxic Substances Control
Chief of Operations
Office of Military Facilities
Loretta K. Barsamian Date
San Francisco Bay Regional Water Quality Control Board
Executive Officer
Walter S.Hogle, Jr. • Date
Lieutenant General,-USAF
Air Mobility Command
Chairperson, Environmental Protection Committee
RDD-SFO/980960020.DOC (IN8212.DOC)
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PARTI DECLARATION
Lead and Support Agency Acceptance
of the Interim Ground-water Record of Decision for
the WABOU, Travis Air Force Base
This signature sheet documents the agreement between the United States Air Force, the
United States Environmental Protection Agency and the State of California, by the
California Environmental Protection Agency, Department of Toxic Substances Control, and
the San Francisco Bay Regional Water Quality Control Board on the Interim Groundwater
Record of Decision for the WABOU at Travis Air Force Base. The respective parties may
sign this sheet in counterparts.
Daniel D.Opalski Date
Chief
Federal Facilities Cleanup Branch
U.S. Environmental Protection Agency, Region DC
Anthony J. Landis, P.E. Date
California Environmental Protection Agency
Department of Toxic Substances Control
Chief of Operations
Office of Military Facilities
Loretta K. Barsamian
San Francisco Bay Regional Water Quality Control Board
Executive Officer
Walter S.Hogle, Jr. Date
Lieutenant General, USAF
Air Mobility Command
Chairperson, Environmental Protection Committee
RDD-SPO/9B0960020.DOC (LNB212JX3C)
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Lead and Support Agency Acceptance
of title Interim Grotxndwater Record of Decision for
the WABOU, Travis Air Force Base
This signature sheet documents agreement between the United States Air Force and the
United States Environmental Protection Agency and the State of California, by the
California Environmental Protection Agency, Department of Toxic Substances Control, and
fiie San Francisco Bay Regional Water Quality Control Board on the Interim Groundwater
Record of Decision far the WABOU at Travis Air Force Base. The respective parties may
sign fhis sheet in counterparts.
Daniel D. Opalski Date
Chief
Federal Facilities Cleanup Branch
US. Environmental Protection Agency, Region IK
Anthony J.Landis,P.B. Date
California Enrironmental.PrcrtEction Agency
Department of Toxic Substances Control
Chief of Operations
Office of Military Facilities
Loretta K. Barsamian Date
San Francisco Bay Regional Water Qnatity Control Board
Executive Officer
Walter S.Hogte, Jr. -A f\ Date
Lieutenant General, USAP^ V^_^J
Air Mobility Command
•Chairperson, Environmental Protection Committee
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PART II
Decision Summary
The Decision Summary includes the findings, evaluations, decision-making process, and
selected remedial actions for the West/Annexes/Basewide Operable Unit (WABOU)
Groundwater Interim Record of Decision (IROD). Section 1.0 describes the physical and
ecological setting of Travis Air Force Base (AFB). Section 2.0 provides an overview of non-
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and
CERCLA environmental programs at Travis AFB. Section 3.0 summarizes the nature and
extent of groundwater contamination as presented in the WABOU Remedial Investigation
(RI) Section 4.0 presents the remedial alternatives that were considered and the comparison
of the alternatives to the criteria set forth in the National Contingency Plan (NCP) as pre-
sented in the WABOU Feasibility Study (FS). Section 5.0 identifies the selected interim
groundwater remedies and the rationale for their selection. Section 6.0 presents the appli-
cable or relevant and appropriate requirements (ARARs) and performance standards for the
interim actions. Section 7.0 is the list of references.
1.0 Travis AFB Description
Travis AFB is located midway between San Francisco and Sacramento, California, about
3 miles east of downtown Fairfield in Solano County. The Base occupies 5,025 acres. In
addition, the Base maintains ownership of or administrative control over 11 annexes at
offbase locations. Approximately 17,000 military and civilian personnel are present daily on
the Base (Weston, 1993). Maps of the regional location of Travis AFB and annexes are
presented on Figure 1-1.
Travis AFB is currently part of the Air Mobility Command (AMC) and is host to the 60th Air
Mobility Wing (AMW). The AMW operates C-5 Galaxy cargo aircraft and KC-10 Extender
refueling aircraft. The primary missions of Travis AFB since its establishment have been
strategic reconnaissance and airlift of freight and troops.
1.1 Physical Description
Topography at Travis AFB is characterized by a gently sloping to nearly flat ground surface
with variations in topographic relief of up to 50 feet. Elevations at Travis AFB range from
over 100 feet above mean sea level (msl) near the northern boundary to less than 20 feet
above msl near the south gate. The ground surface generally slopes to the south or south-
east at about 30 feet per mile. Areas surrounding Travis AFB have a varied topography.
Within the WABOU, the ground surface elevation ranges from more than 100 feet above
msl in the northwest to less than 30 feet above msl in the southern area.
The Travis AFB area climate is characterized as Mediterranean, with wet winters and dry
summers. The Base is located near the Carquinez Straits, which is the major break in the
Coast Range. Travis AFB usually experiences mild temperatures because of its proximity to
flDD-SFO/980960015.DOC (LNB209.DOC)
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TRAVIS
AIR FORCE BASE
NAVAIDTVOR
(ANNEX 2)
Q
CYPRESS LAKES
GOLF COURSE
(ANNEX 10)
RESERVOIR FACILITIES
1510 & 1516 (ANNEX 7)
NAVAID OUTER
MARKER (ANNEX 4)
VICINITY MAP
Not To Scab
NORTHERN SACRAMENTO
RAILROAD (ANNEX 11)
RESERVOIR FACULTIES
1512 ft 1520 (ANNEX 8)
RESERVOIR FACILITIES
1514 & 1518 (ANNEX 9)
NAVAID MIDDLE
Q MARKER (ANNEX 3)
CEMENT HILLS
COMMUNICATIONS
(ANNEX 5) O
TRAVIS AIR FORCE BASE
O
SUISUN DOCK
(ANNEX 1)
O
POTRERO HILLS
(ANNEX 6)
FIGURE1-1
TRAVIS AFB/ANNEXES LOCATION MAP
WEST/ANNEXES/BASEWID6 OPERABLE UNIT (WABOU)
WABOU GOUNDWATER IROO
TRAVIS AIR FORCE BASE, CALIFORNIA
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PAflT II DECISION SUMMAHY
the Carquinez Straits and the coast. The mean annual temperature is 60° F. The lowest
empeSures occur in January, with a mean of 46° F. The highest temperatures occur«.July
andAugust, with a mean of 72° F. Monthly mean relative hunudity typicaUy ^ges torn a
low of 50 percent during June to a high of 77 percent during January. The mean annual
relative humidity is 60.5 percent.
Travis AFB averages 17.5 inches of rain annually. Approximately 84 percent of the annual
p Citation occurs during the winter season of November through March January is the
wettest month, averaging 3.7 inches of precipitation; July is the dnest month averaging
0.02 inch of precipitation.
Evapotranspiration ranges from about 50 to 75 inches per year. However, because.most
precipitation occurs in the winter, and most evaporation takes place in *e ™*r^s
apparent "net annual negative precipitation" has little impact on water infiltration through
the soil column or on groundwater recharge.
Travis AFB experiences sea breezes during the summer because of its proximity to the
Ca* quinez Struts. The average annual wind speed is 8 knots, with a winter average of 5 to
6 toots and a summer average of 12 knots. The predominant wind directions are from the
southwest and west-southwest.
1.2 Land Use
Travis AFB occupies 5,025 acres of land near the center of Solano County, California, and is
Sed appSately 3 miles east of downtown Fairfield and 8 miles south of downtown
Vacaville (see Figure 1-1). Solano County's population in 1990 was 340,421
Spar^erftof CoxLerce/U.5. BuL£ of the Census; 1990^ ^^^^
estimated to have grown to 373,923 by 1994 (State of California, Department of Finance,
1994). During the 1980s, the population of Solano County increased nearly 45 percent
(U.S Department of Commerce/U.S. Bureau of the Census, 1990). However, the rate of
growth has declined since 1990. The projected population growth between 1990 and 2000 is
47 4 percent for the City of Fairfield and 33.6 percent for Solano County overall (Association
of Bay Area Governments, 1990).
According to the Travis AFB Office of Public Affairs, currently 7,750 active military per-
fomefand 3,323 reservists are employed at Travis AFB. Approximately 5 613 people live in
3?^6 onbase housing units. There are 3,006 civilians employed at Travis AFB. Approxi-
mately 17,000 people are onbase on a daily basis.
The land use areas of Travis AFB are grouped into eight functional categories:
. Mission-Uses are closely associated with the airfield and include facilities such as
maintenance hangars and docks, avionics facilities, and other ^ainte^^\ba^rs
Aircraft operations facilities include control towers, Base operations, flight simulators,
and other instructional facilities.
. Administrative—Uses include personnel, headquarters, legal, and other support
functions.
11
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PAHT II DECISION SUMMARY
. Community—Uses include both commercial and service activities. Examples of
^mTerciaUses include the Base Exchange, dining halls service stationancI clubs;
service uses include the schools, chapel, library, and the fairuly support center.
. Housing-Uses include both accompanied housing for families and unaccompanied
housing for singles, temporary personnel, and visitors.
. Base Support/Industriat-Uses are for the storage of supplies and maintenance of Base
facilities and utility systems.
. MedicaV-Uses include facilities for medical support, including the David Grant
Medical Center.
. Outdoor Recreation-Uses include ball fields, golf course, equestrian center, swimming
pools, and other recreational activities.
. Open Space-These areas are used as buffers between Base facilities and to preserve
environmentally sensitive areas.
The lands surrounding Travis AFB on the northeast and east are primarily used for ranch-
hfg and iazing. Area? to the south are a combination of agricultural and marshland. A few
co^erdal/light industrial areas are present to the north of the Base. The area west of
Travis AFB is predominantly residential.
Land use within the WABOU consists of open grasslands, light industrial s«PP«t
administrative areas, personnel training areas, arnmumhon storage,;"*£
areas. Land use at and surrounding the annexes component of the WABOU i
1.3 Ecology
Travis AFB has a variety of terrestrial and aquatic/wetland habitats and wildlife that are
typical of the region. The information used in identifying biological »™W™ ^J?1.
E fieVd studif s and reports produced by Biosystems (1993a, 1993b 1994), CH2M HILL
(1995,1996), Jacobs Engineering Group (JEQ (1994a, 1994b), Rad.an (1994), and Weston
(1995a, 1995b).
1.3.1 Terrestrial Habitats
The terrestrial habitats at Travis AFB and adjacent areas consist of herb acf"s-dominatefd.
habi a s (annual grassland, pasture, and early ruderal habitat) and urbarvhabUat (mdustoal
areas, lawns, and ornamental plants) according to the California Department of Fish and
Gam; (CDFG) classification system (Mayer and Laudenslayer, 1988). Aqu-^/wetbnd
habitats at Travis AFB include riverine (Union Creek) and riparian habitat, lacustrine (Duck
Pond), and herbaceous-dominated wetlands marshes, and vernal pools.
In general, annual grassland habitat is dominated by non-native plant species such as
slender wild oat (Avena fatua), fescues (Festuca), soft chess (Bromus hordeaceus), held
bindweed (Convolvulus arvensis), and yellow star-thistle (Centaurea solst^ahs) Some nahve
plants, such as bunchgrass (F. viridula) and johnny-tuck (Triphysana eriantha) may also be
found, usually associated with undisturbed areas.
12
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PART II DECISION SUMMARY
Mowed/disced grassland is generally composed of soft chess, Italian ryegrass (Lohum
multiflorum), and wild oats. Pasture grassland can contain varying frequencies of filaree
(Erodium sp.), ripgut brome (Bromus diandrus), soft chess, Italian ryegrass, and yellow star-
thistle Ruderal grasslands, on the other hand, contain higher numbers of perennial species
and in some areas, woody species such as coyote brush (Baccharis pilularis), eucalyptus
(Eucalyptus sp.), Peruvian pepper-tree (Sdiinus molle), and black locust (Robinia pseudoacacia).
The urban habitat onbase contains maintained lawns as well as trees and shrubs such as
eucalyptus, Fremont cottonwood (Populus fremontii), arroyo willow (Salix lasiolepis), and
coyote brush. Most isolated stands of shrubs or trees are located within or near urban areas,
permanent water sources, or near artificial surface mounds (for example, rail lines, blast
protection, and building/road foundations.
1.3.2 Aquatic/Wetland Habitats
Herbaceous wetland vegetation is found along the permanent (natural or artificial)
drainages onbase and can also occur seasonally within vernal pools, swales, and ditches.
Native species include salt grass (Distichlis spicata); non-native species include meadow
fescue (Festuca elatior), sickle grass (Parapholis incurua), and cattails (Typha sp.). Vernally
inundated areas support seasonal vegetation such as non-native Mediterranean barley
(Hordeum murinum ssp. leporinum) and brass buttons (Cotula coronopifolia) and native plants
such as downingia (Downingia sp.) and toad rush (Juncus bufonius).
Vernal pools are shallow depressions or small, shallow pools that fill with water during the
winter rainy season, then dry out during the spring and become completely dry during the
summer. The vernal pools at Travis AFB contain indicator species such as goldfields
(Lasthenia fremontii), coyote thistle (Eryngium vaseyi), dwarf woolly-heads (Psilocarphus
brevissimum), water pygmy-weed (Crassula aquatica); and one or more species of downingia
and popcornflower (Plagiobothrys sp.).
Although a few willows and coyote brush can be found along Union Creek, the dominant
plant species found in the riparian zone of Union Creek are mainly herbaceous and consist
of beardless wild rye (Leymus triticoides), broad-leaved pepperwort (Lepidium latifolium),
Harding grass (Phalaris aquatica), and saltgrass. Hydrophytes such as cattails and rushes are
also common.
1.3.3 Wildlife
Terrestrial vertebrates associated with non-native annual grasslands are commonly found
onbase. Typical avian species include ring-necked pheasant (Phasianus colchicus), American
kestrel (Falco sparuarius), American robin (Turdus migratorius), and the western meadowlark
(Sturnetta neglecta). Reptiles observed, or potentially occurring, at the Base include the
western fence lizard (Scelopoms occidentalism gopher snake (Pituophis melanoleucus), and
California red-sided garter snake (Thamnophis sirtalis ssp. infernalis). Common mammals
identified include deer mouse (Peromysciis maniculatus), California ground squirrel
(Spermophilus beecheyf), Botta's pocket gopher (Thomomys bottae), black-tailed hare (Lepus
californicus), and red fox (Vulpes vulpes).
Permanent wetlands and seasonally wet areas support aquatic invertebrates, fish,
amphibians, reptiles, birds, and mammals. Some aquatic invertebrate species observed in
herbaceous wetlands and vernal pools at Travis AFB include vernal pool fairy shrimp
HDD-SFa#80960015-DOC(LNB209.DOC) 13
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PART I! DECISION SUMMARY
(Branchinecta lynchi), damselflies, crayfish, and aquatic snails. Amphibian species identified
include bullfrog (Rana catesbeiana), Pacific tree frog (Hyla regilla), and California tiger
salamander (Ambystoma californiense tigrimtm). Aquatic birds observed on or near the Base
include mallard (Anas platyrhynchos), great egret (Casmerodiuis albus), and great blue heron
(Ardea herodias).
Because wildlife use riverine and riparian habitat somewhat similarly, these habitats are
discussed together. Many aquatic invertebrates and amphibians are the same as those
discussed above in herbaceous wetlands and vernal pools. These include damselflies, cray-
fish, aquatic snail, bullfrog, Pacific tree frog, and California tiger salamander. Fish species
include mosquitofish (Gambusia affinis), fathead minnow (Pimephales promelas), threespine
stickleback (Gasterosteus aculeatus), and bluegill (Lepomis macrochirus). Riverine/riparian
habitats are also used extensively by birds and terrestrial mammals for forage, shelter, and
as a source of water. These include red-winged blackbird (Agelaius phoenicus), raccoon
(Procyon lotor), muskrat (Ondatra zibethicus), and beaver (Castor canadensis).
Habitats that support special-status species are considered sensitive habitats. Aquatic/
wetland areas that are considered sensitive include vernal pools, swales, and ditches that
can support special-status plants and animals. Urban environments, scattered throughout
the Base, can also support special-status species. For example, burrowing owls (Speotyto
cunicularia) may use man-made culverts, perches, and bare earth areas that contain burrows
provided by ground squirrels. Loggerhead shrikes (Lanius ludovicianus) may nest on
antenna wires and forage in grasslands. Both owls and shrikes are typical species of the
grassland habitats onbase. Also, vernal pool fairy shrimp have been found in artificially
created depressions that seasonally fill with water.
1.4 Geology and Hydrogeology
This section provides a discussion of the regional geologic setting in the vicinity of Travis
AFB, as well as specific geologic conditions in the WABOU. This information is presented to
provide a context for discussions on the potential migration of contaminants through the
soil column and in groundwater.
1.4.1 Geology
Travis AFB is located on the western edge of the Sacramento Valley segment of the Great
Valley Geomorphic Province. This province is a sediment-filled synclinal basin with a
northwest-to-southeast-oriented axis. The Coast Range Geomorphic Province, which
consists of folded and uplifted bedrock mountains, lies just to the west of Travis AFB
(Thomasson et al., 1960; Olmsted and Davis, 1961).
The WABOU is located on the western flank of the truncated anticline that traverses Travis
AFB in a northwesterly to southeasterly direction. The axis of the anticline runs through the
EIOU in the vicinity of Facility 363, about 2 miles east of the WABOU boundary. Early
Eocene Epoch Domengine Sandstone, which is the oldest sedimentary unit exposed at the
Base, is exposed along the axis of the anticline.
Bedrock units that outcrop in the vicinity of Travis AFB include (from oldest to youngest)
the Domengine Sandstone, the Nortonville Shale, the Markley Sandstone, the Neroly
Sandstone, and the Tehama Formation, as shown on Figure 1-2. Bedrock at the
RDD-SFO/9B0960015.DOC(LNB209.DOC)
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PART II DECISION SUMMARY
North/East/West Industrial Operable Unit (NEWIOU) has been defined as consisting of
consolidated to semi-consolidated sedimentary rock. It has been distinguished from the
overlvine unconsolidated sediment by such criteria as fissility, cementation, bedding, blow
counts, color, texture, and gradation into competent rock (Weston, 1995a). Because of its
lower permeability relative to the unconsolidated alluvium that overlies it, the bedrock may
form a boundary for groundwater flow and therefore influence the migration of
contaminants in groundwater. Table 1-1 is a stratigraphic column that summarizes the
lithology and age of the geologic units in the area.
TABLE 1-1
Stratigraphic Column o
Million
Years
Ago Era
1.8 Cenozoic
5
{ Geologic Units at Travis AFB
Period Epoch
Quaternary Pleistocene
and Recent
Pliocene
Geologic
Unit
Younger Alluvium
Older Alluvium
Bay Mud
Tehama Formation
Litnoloqic Description
Interbedded clays, silts,
sands and gravels,
continental
Interbedded clays, silts,
sands, and gravel,
continental
Interbedded clays, silts,
sands and qravel, continental
Interbedded gravels, sands,
silts and clays, partially
consolidated, occasional
volcaniclastic sediments;
continental
Possible
Range of
Thickness
0-70 feet
0-100 feet
Unconformity
27.5
Tertiary Miocene
Neroly Sandstone
{San Pablo Group)
Interbedded sandstone,
siltstone, and shale,
distinctive bluish color;
marine
0-60 feet
Unconformity
55
Oliqocene
Eocene
Markley Sandstone
Massive micaceous, arkosic
0-60 feet
Nortonville Shale
Domengine
Sandstone
sandstone, interbeds of
siltstone and shale, marine
Predominantly dark gray
marine shale and siltstone,
minor sandstone, coal and
glauconitic sandstone unit
Coarse-grained sandstone,
minior siltstone and shale
interbeds, gray to brown,
marine (in outcrop only as
mapped by Sims et al.,
80 feet
50 feet
Paleocene
Unnamed
Formation (?)
Interbedded shale, siltstone,
and thinly laminated friable
sandstone, marine (as
mapped by Sims et al., 19731
Source: Sims et al., 1973.
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PART II DECISION SUMMARY
The Tehama Formation consists of poorly sorted deposits of clay, silt,Clayey silt sandy^ silt
and clay, and silty sand, containing generally thin lenses of gravel and sand. In areas of
outcrop, it consists chiefly of siltstone, sandstone, and conglomerate. ™eTeham*
formation is widespread in the northern, northwestern, and western Sacramento Valley,
averages about 2,000 feet in thickness (Page, 1986). However, the mickness of the
formation beneath the WABOU is unknown.
Travis AFB is located on the northeastern margin of the Fairfield-Suisun Basin astride the
VaTFault. Travis AFB lies on alluvial fans that extend from the Vaca Mountains to the
Suisun Marsh. These fans were deposited by the Ulatis, Union, Alamo, Laurel, and^Suisun
Creeks. Most of the alluvial material was deposited prior to the last period of glacianon
du*£ the Pleistocene Epoch, and is referred to as Older Alluvium. The parent rocks for the
alluvium at Travis AFB include metasediments, serpentirutes, ultramafccroc^ and the
Sonoma Volcanics (Olmsted and Davis, 1961; Wagner and Bortugno, 1982) The drainages
enough the alluvial fans during the last glacianon, in response to the global lowering of
Ae £a level. As the sea level has risen during the last 15,000 years, the drainages have fifed
again with alluvium. This material is referred to as Younger Al uvium. At Travis AFB the
overall thickness of the alluvium ranges from 0 to approximately 70 feet, but is generally
kss than 50 feet. West of Travis AFB, the thickness of the alluvium mcreases to over 200 feet
Aomasson et al, I960). Some topographic relief in the form of very low ndges is provided
by outcrops of sedimentary rocks characterized as bedrock in the Travis AFB area.
The younger and older deposits are distinguished at the surface by the difference in
maturity of their soil profiles. The portion of the alluvium near the ground surface has been
^dtyorweatheredPover time byphys-l Ae^l ^dUolo^ ^or^^o^r
Alluvium generally has an immature soil profile; the Older Alluvium general^ has a well-
developed mature soil profile. Most of the sediment encountered at Travis AFB consists of
Older AUuVium. The Younger Alluvium overlies the Older Alluvium and is found only m
the northeastern portion of the Base.
Soil develops within geologic material exposed at the Earth's surface as the material is
altered through physical, chemical, and biological processes. The nature o£soil is »r,t part a
function of climate, surface slope, time of exposure at the Surface,and the type of original
(Lent) material. Soils in the vicinity of Travis AFB are primarily silt and clay loams that
exhibit low permeabilities and poor drainage characteristics.
The majority of the Base, including the WABOU, is covered with soils derived from
Pleistocene Epoch Older Alluvium designated as the Antioch-San Ysldrc.Complex^ This
complex comprises about 45 to 50 percent Antioch soil series and 35 to 45 percent San
Ysidro soil series, with the remaining percentage composed of the So ano soil series and
Pescadero soil series. The soils are old and are characterized by a well-developed soil
profile.
1.4.2 Hydrogeology
Travis AFB is located along the eastern edge of the Fairfield-Suisun Hydrogeologic Basin.
The Fairfield-Suisun Basin is a hydrogeologically distinct structural depression adjacent to
ti*Sacramento Valley segment of the Central Valley Province. The basin is bordered to the
north by the Vaca Mountains and to the east by the ridge that runs *^n*%"££
of the North Operable Unit (NOU) and East Industrial Operable Unit (EIOU). The basin
17
RDD-SFO/980960015.DOC(LNB209.DOC)
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PART II DECISION SUMMARY
slopes south toward the Suisun Marsh; consequently, groundwater and surface water at
Travis AFB tend to flow south to Suisun Marsh (California Department of Water Resources,
1994).
The primary water-bearing deposits in the region surrounding Travis AFB are the coarse-
grained sediments (sand and gravel) within the Older Alluvium and Younger AUuvmm.
The bedrock units generally do not yield groundwater of usable quantity or quality in the
Fairfield-Suisun Basin (Thomasson et al., 1960).
1.4.3 Groundwater Gradient and Flow
The eroundwater gradient describes the differences in hydraulic potential that result in
eroundwater flow. The direction of the regional groundwater gradient is generally toward
the south or southeast. Groundwater recharge occurs from the direct infiltration of rainfall
on the valley surface and from the infiltration of runoff through local stream andoreek
beds. Natural groundwater discharge occurs at the marshlands located near the Potrero
Hills, south of Travis AFB (Thomasson et al., 1960).
The general direction of groundwater flow at Travis AFB is toward the south, similar to the
regional gradient. However, local variations (groundwater mounds and depressions) exist
within the boundaries of Travis AFB. Changes in the groundwater gradient are normally
related to the presence of lower permeability consolidated materials ( bedrock ) m the
subsurface, and the distribution of alluvium with relatively higher permeability. Ground-
water typically flows away from the bedrock ridges, and toward the subbasins that contain
thicker sequences of alluvial materials. Therefore, the bedrock ridges bordering the
subbasins correspond with potentiometric highs in the groundwater elevation map.
The maximum horizontal hydraulic gradient in the shallow groundwater at Travis AFB
outside of the WABOU is approximately 0.02 foot/foot at the groundwater mound near the
old Base hospital. The minimum horizontal gradient in the upper portion of the aquifer is
approximately 0.002 foot/foot near the southern border of Travis AFB. The average
magnitude of the groundwater gradient in the shallow groundwater is approximately
0 005 foot/foot. The horizontal hydraulic gradients in the deeper zones of the alluvial
aquifer range from approximately 0.003 to 0.01 foot/foot (Radian, 1996a).
Groundwater flows in a generally southerly direction in the WABOU, as shown on
Figure 1-3 Variations in this flow regime are most pronounced in the north-central portion
of the WABOU, in the vicinity of the topographic high point where the Tehama Formation
outcrops. Grouhdwater flows radially away from the topographic high point m this area,
and then curves back to the south. A subsurface ridge of the Tehama Formation that
extends south from the outcrop also affects the groundwater flow direction (Figure 1-3).
Groundwater flowlines appear to curve away from this ridge in the vicinity of sites such as
Building 755. The groundwater gradient in the WABOU ranges from about 0.005 foot/foot
near the mound to about 0.06 foot/foot at the southern end of the WABOU.
18
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_. -^-=- >^
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PART II DECISION SUMMARY
Landfill 3 is located on a bedrock ridge near a groundwater divide. Groundwater here
recharges the adjacent basins, and the vertical gradient is downward, ranging from about
0.2 foot/foot to about 0.35 foot/foot. Annual fluctations in the piezometric surface averaged
about 2 to 5 feet. Water levels reached their low point just prior to the rainy season in late
1994, at the end of a multi-year drought. After 1994, the groundwater levels rose in the
wells 5 to 6 feet during the wetter years of 1995 and 1996.
As previously mentioned, the Older Alluvium is the source of most of the groundwater
supply in the Fairfield-Suisun Basin. The consolidated bedrock units that underlie the Older
Alluvium do not yield groundwater of usable quantity or quality. The Older Alluvium
reaches a maximum thickness of only about 200 feet (Thomasson et al., 1960). Investigations
at Travis AFB indicate that the maximum thickness of the Older Alluvium at the Base is
only about 70 feet (Radian, 1996b).
The Older Alluvium is extremely heterogeneous, and no discrete aquifer units were
observed during the WABOU RI that could be correlated from site to site. In addition, a
consistent vertical gradient up or down does not appear to be present in the WABOU. The
Older Alluvium, therefore, should be regarded as a single hydrogeologic unit. In this
regard, "shallow" and "deep" groundwater have little meaning in the WABOU.
Groundwater is found under water table or semi-confined conditions, and flows in a
predominantly horizontal direction.
Groundwater will flow preferentially through sediments with relatively higher
permeability, such as silty sands and sands.
1.4.4 Aquifer Tests
The hydrogeologic parameters of hydraulic conductivity and porosity are needed to
calculate groundwater flow velocities. To estimate the hydrogeologic parameters of the
alluvial deposits and bedrock, aquifer slug tests and aquifer pumping tests have been
conducted at Travis AFB between 1988 and 1996. Table 1-2 summarizes the values of
hydraulic conductivity that have been calculated from these tests. The results of these ^
aquifer tests indicate the horizontal hydraulic conductivity (K) of the alluvium beneath*
Travis AFB ranges from about 0.0001 foot per minute (fpm) to about 0.08 fpm, with an
average of about 0.02 fpm. Vertical hydraulic conductivities calculated from aquifer
pumping test data collected at MW245 and MW214 within the EIOU ranged from
1.21 x 10"4 fpm to 2.29 x 10'3 fpm (Radian, 1996a).
The wide range of hydraulic conductivities calculated from pump tests conducted at Travis
AFB reflects the natural variability in permeability of the geologic units that are present.
The lower range of hydraulic conductivities calculated for the vertical direction relative to
the horizontal direction indicates that groundwater will flow more easily in the horizontal
direction than in the vertical direction. Even in the presence of a vertical gradient, if the
ratio of horizontal to vertical hydraulic conductivity is approximately 100 or more,
groundwater flow will essentially be horizontal (Freeze and Cherry, 1979).
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PART II DECISION SUMMARY
TABLE 1-2
Summary of Hydraulic Conductivity Values Derived from Aquiter Tests Conducted at Travis AFB
Hydraulic Conductivity (K fpm)
Geologic Unit
Younger Alluvium
Older Alluvium
(vertical K)
Sandstone Bedrock
Shale or Siltstone Bedrock
Number of
Tests*
9
30
(2)
2
4
Minimum
0.0005
0.0001
(0.000121)
0.0025
0.0006
Maximum
0.079
0.074
(0.00229)
0.021
0.0415
Mean
0.020
0.027
(0.0012)
0.0088
0.020
"Identity of wells provided in Radian (1996b).
This fact is reinforced in the vicinity of Travis AFB by the fact that the regional discharge
points for groundwater in the Fairfield-Suisun Basin are nearby Union Creek or Suisun
Marsh. Therefore, dissolved contaminants that reach the water table will tend to migrate
horizontally, with little opportunity for vertical migration before discharging. Dissolved
contaminants in groundwater will also tend to migrate preferentially in geologic layers of
higher permeability.
Based on the mean hydraulic conductivity in the Older Alluvium (Table 1-2), with an
average groundwater gradient of 0.005 foot/foot and an assumed average effective porosity
of 0.20, the average linear velocity of groundwater flow within the Older Alluvium is about
350 feet per year. Using the maximum value of hydraulic conductivity, the groundwater
flow velocity in the Older Alluvium ranges up to about 970 feet per year. The average
groundwater velocity calculated in the EIOU from pump tests performed in a variety of
geologic settings was 110 feet per year (Weston, 1995b).
1.4.5 Groundwater Use
Intensive extraction of groundwater generally occurs only to the west of Travis AFB and
Fairfield where the alluvium is thicker and contains a greater abundance of coarse-grained
sediment. Groundwater wells in the area of Travis AFB are limited to domestic, stock-
watering, and irrigation wells with typical screened depths of within 100 feet of ground
surface (Weston, 1995b). Domestic wells, several of which are downgradient from Travis
AFB, are used typically for households and gardens (Weston, 1995b). Based on the large
distance (more than 4,500 feet) between the contaminated groundwater in the WABOU and
the nearest domestic well, and the local groundwater flow velocity, it is highly unlikely that
the downgradient domestic wells will ever be impacted by the contaminated groundwater.
The groundwater cleanup actions of the four WABOU sites protect these offbase wells.
However, if the contaminated groundwater from these sites reached an offbase domestic
well, an alternative water supply would be provided.
No onbase wells are used for potable water production. However, several wells located
4 miles north of Travis AFB, at the Cypress Lakes Golf Course (Annex 10), produce 400 to
500 million gallons of water per year. This well water is mixed with surface water
purchased from the City of Vallejo to supply potable water to Travis AFB. The Fairfield
public water supply field is located approximately 3 miles west of Travis AFB. The large
ROD-SFO/980960Q15.DOC (LNB209.DOC)
21
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PART II DECISION SUMMARY
production wells at the golf course and in Fairfield tend to be deeper than the nearby
^omPsHr wells, ranging up to 1,000 feet in depth.
domestic wells, ranging up
1.5 Surface Water
1 5 surrace waier . .
Francisco.
WOU± *e wiBOU^d ^als Ragsdale Street for about 4,OM fee,, shown on
WOU *e wBOUd as agsae ree , ,
bZndary. Surface water from Hill Slough flows into Smsun Marsh.
Union Creek.
Union \_iee*"
22
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PART II DECISION SUMMARY
the vicinity of the Base empty into the Suisun Marsh. No springs have been recorded within
the confines of Travis AFB.
Surface water pathways, as defined in this WABOU Groundwater IROD, include Union
Creek, drainage channels, the storm and sanitary sewer system, and the backfill material
surrounding underground sewer lines. These pathways are a potential means for ground-
water to interact with surface water. Based on the locations and depths of the sewer lines in
the WABOU and the groundwater level measurements in the vicinity of the four WABOU
sites, there is no interaction between surface water and contaminated groundwater in the
WABOU.
BDD-SFO/9fl0960015.DOC(LNB209.DOC) 23
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PART II DECISION SUMMARY
2.0 Overview of Travis AFB Environmental Programs
The Travis AFB Environmental Management Office is divided into three branches:
Compliance, Restoration, and Pollution Prevention. This section describes each branch and
the programs that are designed to comply with current federal and state environmental
regulations.
2.1 Compliance Branch
Travis AFB maintains several active environmental compliance programs that are described
below.
2.1.1 Air Force Regulations
The Air Force has developed a parallel set of environmental regulations to the federal
environmental regulations. These Air Force regulations are designed to ensure that federal
requirements are implemented in an appropriate manner at Air Force installations. Air
Force instruction AH 32-7005 sets up an Environmental Protection Committee to oversee
management of all environmental programs at each installation. The Air Force environmen-
tal compliance regulations that parallel the federal environmental regulations are divided
into the following subject areas:
Air Quality Compliance
Water Quality Compliance
Solid and Hazardous Waste Compliance
Storage Tank Compliance
Environmental Impact Analysis Process
Integrated Natural Resource Management
Cultural Resource Management
2.1.2 Management Action Plan and Base General Plan
The Travis AFB Management Action Plan (MAP) summarizes the current status of the
Travis AFB environmental compliance, restoration, and pollution prevention programs, and
presents a comprehensive strategy for implementing response actions necessary to protect
human health and the environment. Travis AFB produced the most recent version of the
MAP in January 1997. Travis AFB environmental staff and Air Force headquarters use the
MAP to direct and monitor environmental response actions and to schedule activities
needed to resolve technical, administrative, and operational issues.
The Travis AFB General Plan (the Plan), also known as the Base Comprehensive Plan, a
companion document to the MAP, provides an organized, systematic, and comprehensive
approach to current and future planning and development. The Base General Plan is a tool
that addresses a multitude of installation requirements and assists in the long-range growth
of the Base, including natural resources, environmental protection, land use, airfield opera-
tion, utilities, transportation, and architectural compatibility. Of particular importance is its
role in environmental protection. The Plan addresses proper hazardous waste management
and recognizes CERCLA-related activities through proper land use at Travis AFB.
RDD-SFO/980960015.DOC(LNB209.DOC) 24
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PART II DECISION SUMMARY
Section 5.6 addresses the implementation of land use restrictions to the Plan based on
CERCLA-related activities.
2.1.3 Resource Conservation and Recovery Act and Hazardous Waste Management Program
Travis AFB operates as a generator and facility for hazardous waste management under the
Resource Conservation and Recovery Act (RCRA) and State of California hazardous waste
management programs. Travis AFB received a Part B hazardous waste facility storage
permit from the California Department of Toxic Substances Control Division (DTSC) and
the U.S. Environmental Protection Agency (U.S. EPA) on 5 March 1993.
2.1.4 Petroleum-only Contaminated Sites Program
The Travis AFB Petroleum-only Contaminated Sites (POCOS) program is designed to
manage on base petroleum-related contamination sites. Travis AFB and the regulatory
agencies agreed to remove the POCOS from the Travis AFB CERCLA program because the
law excludes petroleum as a CERCLA contaminant. The Air Force will address petroleum
contamination under CERCLA if it is commingled with CERCLA contaminants.
POCOS are typically associated with surface and sub-surface releases from fuel spills,
piping leaks, oil-water separators, or underground storage tanks (USTs). The POCOS
program includes the removal of leaking USTs and the remediation of petroleum-only
contaminated soil and groundwater. An example of a POCOS that was removed from the
CERCLA program by the regulatory agencies and the Air Force is the North/South Gas
Station site. The San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) is
the lead oversight agency for this program.
2.1.5 Stormwater Discharge Permit
Travis AFB monitors Stormwater outfalls in compliance with its California National
Pollution Discharge Elimination System (NPDES) permit. The ongoing monitoring program
was developed in 1992. The Air Force conducts surface water sampling and reporting
according to the permit requirements. The SFBRWQCB is the lead oversight agency for
Stormwater discharges.
2.2 Restoration Branch
The Restoration Branch manages the Travis AFB Installation Restoration Program (IRP)
which was initiated in 1983 to investigate the nature and extent of reported hazardous
waste releases to the surrounding environment (Engineering-Science, 1983). On the basis of
the evaluation of IRP data by the U.S. EPA, Travis AFB was placed on the National
Priorities List (NPL) on November 21,1989 (54 Federal Register 48187).
The Air Force, U.S. EPA, DTSC, and SFBRWQCB negotiated and signed a Federal Facility
Agreement (FFA) in September 1990. The FFA is a legally binding document that
establishes the framework and schedules for the environmental cleanup at Travis AFB. This
document also requires Air Force compliance with the NCP, CERCLA, RCRA guidance and
policy, and state laws and regulations.
RDD-SFO/98096001S.DOC (LNB209.DOC) 25
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PART II DECISION SUMMARY
CERCLA was passed in 1980 and amended by the Superfund Amendments and
Reauthorization Act (SARA) in 1986. This law established a program to «^*"*»
contaminated with hazardous constituents to protect public health and the environment
CERCLA established a series of steps to investigate site contamination and design and
implement appropriate remedial actions at these sites. The major steps are described below.
2.2.1.1 CERCLA Steps
Remedial Investigation (RI)-The RI is used to collect data to characterize site conditions,
foTetermine the nature of me waste, and to assess risk to human health and the ermron-
ment The WABOU RI used a phased and sequenced approach to minimize collection of
unnecessary data and maximize data quality. Initial data collection efforts provided a basic
understanding of site characteristics. As this basic understanding was ^f'.f^^
data collection efforts focused on filling identified data gaps in the conceptua site model
and gathering the information necessary to support evaluations of remediaalternatives.
The Lults and conclusions of this investigation were published in the ^f Ajanexes/-
Bawide Operable Unit Remedial Investigation Report (Volumes 2-4), 6Ct* Air Mobility Wing,
Travis Air Force Base, California (CH2M HILL, 1997).
Feasibility Study (FS)-The FS is divided into three general phases: development of _
alternatives, screening of alternatives and detailed analysis of alternatives. In the first phase
the technology types and process options available to implement the genera response
SorSTr cSnated soil and groundwater were defined. A technology unplemen^
ability screening was conducted which provided the basis for the selection of representative
process options for soil and groundwater remediation. In the second phase the remedia
alternatives were assembled using the representative process options and the site-specific
""Sons in the WABOU. In the last phase the alternatives were evaluated against seven of
the nine CERCLA criteria. The WABOU FS provided a comparative analysis of alternatives
to identify the advantages and disadvantages of each alternative to assist the decision-
making process. The results of this study were published in the West/Annexes/Basewide
Operable Unit Feasibility Study, 60* Air Mobility Wing, Travis Air Force Base, California
(CH2M HILL, 1998).
Proposed Plan (PP)-The PP presents to the public the preferred alternative for each.site
and the rationale for the preferences. The WABOU Groundwater PP (Travis AFB, 1998)
gave the public an opportunity to comment on the preferred groundwater alternatives
during a 30-day publk comment period (April 8,1998 to May 8,1998). It was published and
maHed to all community members on the Travis AFB Community Relations list ,ust prior to
the start of the public comment period. The Air Force formally presented thepreferred
groundwater alternatives to the public at the April 23,1998 public meeting. The Air Force
also published a WABOU Soil PP to present to the public the preferred alternatives for the
WABOU soil sites. A separate 30-day public comment period (July 8,1998 to August 8,
1998) and public meeting (July 23,1998) were held to promote public participation in the
decision-making process.
Record of Decision (ROD)-The ROD presents the selected alternative and final cleanup
levels at each site. It summarizes all CERCLA activities at each site and documents that the
Air Force and the regulatory agencies are in agreement as to how the cleanup is to take
place. Travis AFB and the regulatory agencies have agreed to use an IROD to quickly start
26
RDD-SFO/980960015.DOC (LNB209.DOC)
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PART II DECISION SUMMARY
written to document the selected alternatives and the final soil cleanup levels at the
WABOU soil sites.
groundwater site.
reguStory agencies 21 days after the WABOU Soil ROD is signed.
2.2.2 Operable Units
Tniriallv Travis AFB was treated as a single entity with one associated .
ckanup schedule: In May 1993, the FFA was amended and the Base was divided mto the
four Operable Units (OUs) listed below to facilitate the overall cleanup program:
. East Industrial Operable Unit (EIOU)
• West Industrial Operable Unit (WIOU)
. North Operable Unit (NOU)
. West/Annexes/Basewide Operable Unit (WABOU)
Operable unit boundaries are shown in Figure 1-1. In October 1995, the first three OUs were
combined into the North, East, West Industrial Operable Unit.
The WABOU has three main components:
. The western portion of the installation. All four groundwater sites are located within the
western portion of the Base.
. The annexes or noncontiguous parcels of property that are under ^^^^^
Travis installation commander. The boundaries of each annex are denned in the official
records of the Travis AFB Real Property Office.
. Other sites within the installation not being addressed by the other three OUs. These
site were included to ensure that all portions of the Base had been addressed. This is
the "Basewide" component of the WABOU.
27
RDD-SFO/98096001S.DOC (LNB209.DOC)
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PART 11 DECISION SUMMARY
^
backfilled with clean soil.
£-S"S^^
(Radian, 1997).
2.2.4 Treatability and Pilot Studies . WAROII
S^^^^^
Decision for the NEWIOU (Radian, 1997).
and „ ecologto.
Screening Assessment (CH2M HILL, 1996).
2.2.6 Community Participation
process.
The highlights of the community relations activities taken by Travis AFB are presented
below:
28
RDD-SFO/980960015.DOC (LNB209.DOC)
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PAST II DECISION SUMMARY
negotiated an interagency agreement, which includes requirements for community
relations activities based on provisions in federal (and where applicable, state) statutes,
regulations, and guidelines.
Restoration Advisory Board (RAB). In 1994, Travis AFB established a RAB comprised
of representatives of the community and the regulatory agencies. Through its quarterly
meetings and its focus groups, the RAB has provided valuable input about community
concerns regarding the Restoration Program. The Technical Document Review focus
group has reviewed and commented on the draft version of every major report. The
Relative Risk focus group has provided input on the project prioritization, and the
Community Relations focus group is working to reach out to all community members.
The RAB replaced the Technical Review Committee, which met periodically to review
program progress.
Administrative Record/Information Repository. The Air Force established an
Administrative Record to support Air Force decisions related to the Travis AFB IRP. In
addition, the Air Force established a public information repository for the relevant
portion of the Administrative Record at the Vacaville Public Library. Copies of RI
reports, FS reports, Proposed Plans and decision documents for both OUs are available
for public review.
Community Relations Plan (CRP). The Air Force implemented the first Travis AFB
CRP in 1991. The Air Force revised the CRP in 1998. The Travis AFB Remedial Project
Manager (RPM) is currently implementing the CRP.
Mailing List. A mailing list of all interested parties in the community is maintained by
Travis AFB and updated regularly. The mailing list currently totals more than
1,300 names.
Fact Sheets and Newsletters. The Air Force has been publishing fact sheets describing
activities and milestones in the restoration program occasionally since 1993. Since 1995
the Air Force has published and mailed quarterly newsletters to everyone on the
mailing list. The newsletters contain information about public participation, issues of
potential concern to the public, and program updates. The RAB co-chairs also write
columns in each newsletter.
Proposed Plans. The Air Force has mailed copies of NEWIOU and WABOU
Groundwater Proposed Plans to all parties on the Travis AFB mailing list, government
officials, representatives of interested community groups, and members of the media.
Copies are available at three Solano County libraries for public review.
Public Meetings. The Air Force held a 30-day public comment period for the WABOU
Groundwater Proposed Plan (April 8,1998 -May 8,1998). The Air Force held a public
meeting on the evening of April 23,1998 to present the proposed remedial alternatives
for WABOU groundwater sites. At this meeting, representatives from the Air Force, Cal-
EPA/DTSC, and U.S. EPA were present to answer questions about the groundwater
contamination. Questions and comments from the public and responses are included in
Part III, the Responsiveness Summary.
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PART II DECISION SUMMARY
2.2.7 Remedial Design/Remedial Action
2.3 Pollution Prevention Branch
by sampling activities m the IRP-
RDD-SFO/980960015.DOC (UNB209.DOC)
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PART II DECISION SUMMARY
3.0 WABOU Groundwater Remedial Investigation Summary
The primary objectives of the RI were to evaluate the nature and extent of contamination in
the WABOU and assess the potential risks to human health and the environment posed by
the contamination. Following the RI field activities, the data were evaAluated^nd.huma"
health and ecological risk assessments were performed for each site. A quantitative human
health risk assessment (HHRA) resulted in the identification of chemicals of concern (COC)
for each site. Site-related excess lifetime cancer risks, as well as Hazard Indexes (for non-
cancer-causing chemicals) were computed for each COC Similarly, the ecological risk
assessment resulted in the identification of chemicals of ecological concern (COEC) for each
site. Hazard Quotients for various ecological receptors (selected indicator species of plants
and animals) were computed for each COEC.
3.1 Nature and Extent of Contamination
There are four WABOU sites with groundwater contamination. This section presents a brief
description of each groundwater site. Figure 3-1 shows the locations of the WABOU
groundwater sites and the extent of groundwater contamination.
Appendix A provides a brief summary of the description of each WABOU groundwater
site the nature and extent of contamination, the alternatives evaluated in the FS, the
selected interim groundwater action, and the conceptual design for the selected interim
remedy.
Reservoir Facilities 1514/1518 is a WABOU site that did not continue into the WABOU FS.
This active facility has fluoride contamination in groundwater as a result of an above-
ground fluoridation tank leak. Because the leak occurred after the IRP funding eligibility
date (1 January 1984), the site was transferred to the Compliance Branch of the Travis AFB
Environmental Management Office. A description of this site is found in Section 4_17 of the
West/Annexes/Baseivide Operable Unit Remedial Investigation Report (Volumes 1-4), bU Air
Mobility Wing, Travis Air Force Base, California (WABOU RI) (CH2M HILL, 1997).
3.1.1 Building 755 (DP039)
Building 755 is the Travis AFB Battery and Electric Shop. The site consists of Building 755
and a former battery neutralization sump. Past operations have included the recharging
and dismantling of lead-acid and nickel-cadmium batteries. Before 1978, lead-acid solutions
were discharged into a sink inside Building 755. The pipeline from the sink led to a rock-
filled sump approximately 65 feet northwest of the building. This practice was discontinued
in 1978 when the pipeline was dismantled and reconnected to the sanitary sewer system.
The sump was removed in 1993.
Electrical equipment maintenance also took place in this building, and it is apparent that
industrial solvents used in the maintenance, such as TCE, were discharged into the sump.
The highest VOC concentrations were found in samples from beneath the former sump and
sueeest the presence of undissolved TCE beneath the water table. Subsequent groundwater
sampling was used to determine the extent of the VOC plume. The plume has ^grated
1 400 feet to the southeast, consistent with the local groundwater flow direction, and is 800
feet wide TCE is the contaminant that poses the greatest potential risk at this site. Figure A-
1 of Appendix A presents the Building 755 site and a conceptual diagram of the TCE plume.
3t
RDD-SFO/9B0960015.DOC (LNB209.DOC)
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PART II DECISION SUMMARY
There are no discrete surface water drainage pathways at this site. A sanitary sewer line
runs in an east-west direction just south of Ellis Drive. This 8-inch.vitrified clay line is
toted 4 feet below ground surface (bgs). Based on the depth of the water table in the
vkmtty of this sewer line (>15 feet bgs), there is no interaction between the groundwater
and the sewer line.
3.1.2 Landfill 3 (LF008)
Landfill 3 consists of trenches used in the 1970s for the disposal of rinsed pesticide con-
Linens bags, and possibly pesticide container rinsewater (JEG, ^4b).UndhU Seated
within the Weapons Storage Area (Bunker A) in the western portion of the WABOU.
Bunker A is a secured area and is surrounded by fences. The LF03 site comprises about 1
acrTof land, based on the trenches excavated during the WABOU RL The trenches are
currently covered with fill material. There are no storm or sanitary sewer lines in the
vicinity of this site.
Approximately 30 cubic yards of materials were reportedly buried in trenches with varying
2SEL Geophysical surveys were used to identify the locations of these trenches..**
out of nine exploration trenches encountered buried debris dunng the RL The depth of
waste observed was from 5 to 8 feet, and no lining was visible benea* the waste. Materials
excavated during the RI included 1- and 5-gallon metal containers, plastic and paper bags,
o£er paper and plastic debris, 1-gallon glass bottles, and two 55-gallon drums. Labels
found on some of the containers indicated that the containers originally held pesticides and
herbicides. No evidence that other contaminants were disposed of at the landfill was
discovered.
The results of groundwater sampling indicated that pesticides have migrated from the
disposal trenches to the groundwater. Figure A-2 of Appendix A presents a conceptual
diagram of the pesticide plume. Because the trenches are located on a topographic high, the
plume has migrated slowly in a radial direction around the source area.
3.1.3 Building 905 (SS041)
Building 905 is the Travis AFB Entomology Shop that was used to prepare pesticide and
herbicide mixtures from 1983 to 1992. A 3,000-square-foot fenced enclosure outside on the
east side of the building contains a washrack and a storage area. The washrack was
formerly used to wash down tractors used for towing bowsers filled with pesticides and
herbicides. The washrack consisted of a concrete pad with a perimeter berm (i.e., curb) and
a drain that discharged to a tank. The surface soil appears to have received pesticide residue
from spray generated during the washing of pesticide applicator vehicles under windy
conditions The results of groundwater sampling indicated that pesticides have migrated
from the surface soil to the groundwater. There are no storm or sanitary sewer mes in the
vicinity of the groundwater contamination at Building 905. The sanitary sewer line that
supports Building 905 is upgradient of the contaminant plume and is not considered a
preferential pathway. Figure A-3 of Appendix A presents a conceptual diagram of the
pesticide plume.
3.1.4 Building 916(80043)
Building 916 was constructed in 1953 to provide emergency electrical power. The diesel-
powered generators inside the building are located in a cellar, or sump area, that also
33
RDD-SFO/980960015.DOC (LNB209.DOC)
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PART II DECISION SUMMARY
houses sump pumps. Prior to 1991, diesel fuel that had spilled from the generators was
washed down with water and pumped out of the building through one of four pipes. The
pipes discharged onto small concrete spillways constructed for erosion control on the side
slope of the trapezoidal drainage channel that lies east of the building. From the spillways,
wastewater flowed down the side-slope and into the drainage channel. This method of
sump water disposal was discontinued in 1991.
A TCE plume has been identified beneath the drainage channel adjacent to the building.
The source of this plume appears to be the spillway that was used to drain the sump within
the building, although this possibility has not been confirmed. In addition, leaks at a former
transformer pad resulted in deposition of a PCB isomer (PCB-1254) in the nearby soil and
migration to the local groundwater. There are no storm or sanitary sewer lines m the
vicinity of the groundwater contamination at Building 916. The sanitary sewer line that
supports Building 916 is upgradient of the contaminant plume and is not considered a
preferential pathway. Figure A-3 of Appendix A presents a conceptual diagram of the TCE
and PCB plumes.
3.2 Risk Assessments
An HHRA and an ecological risk assessment were conducted using the data collected
during the WABOU RL The objective of a risk assessment is to evaluate the potential risks
resulting from exposure to chemicals detected in environmental media. Since there is no
exposure pathway of the contaminated groundwater at the four WABOU sites to ecological
habitats, these sites pose no ecological risk to the local habitats. Therefore, this section will
address the results of the WABOU HHRA that pertain to groundwater.
The WABOU HHRA was conducted in two phases: a screening risk assessment and a
quantitative risk assessment. Each risk assessment follows the following four steps:
. Identification of Chemicals of Potential Concern (COPC)— chemical concentrations were
compared to U.S. EPA Preliminary Remediation Goals (PRGs) and WABOU inorganic
reference concentrations
• Exposure Assessment— potential pathways by which exposure could occur were
identified, potentially exposed populations were characterized, and the magnitude,
frequency , and duration of exposure were estimated
• Toxicity Assessment— the toxicity of the COPC and the relationship between magnitude
of exposure and adverse health effects were summarized
• Risk Characterization— the toxicity and exposure assessments were integrated to
estimate the potential risks to human health from exposure to site chemicals.
The screening HHRA evaluated chemicals detected in groundwater by comparing them to
chemical-specific water PRGs developed by U.S. EPA Region IX (EPA, 1995). These water
PRGs were developed using default exposure factors for a residential scenario and U.S. EPA
or Cal/EPA toxicity values (whichever are more stringent) to estimate concentrations which
are protective of humans, including sensitive groups, over a lifetime. This is a very conser-
vative screening assessment because no current or future residential land use is planned for
sites within the WABOU. In addition, onsite groundwater is not currently being used for
agricultural, industrial, or domestic purposes.
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PART II DECISION SUMMARY
The purpose of the quantitative HHRA was to evaluate site-specific exposure scenanos.
Because no current or future residential land use is planned in the WABOU, this is an
unlikely future exposure scenario. On the basis of actual current and future planned site
uses, the most likely future exposure scenario is a commercial/industrial worker exposure
scenario. Therefore, a worker exposure scenario was used in the quantitative HHRA.
Table 3-1 presents the potential human health risks posed by the contaminated ground-
water at the four WABOU groundwater sites. The human health risk calculations are
presented in Appendix Gl of the WABOU RI.
3.3 Chemicals of Concern
Based on the results of the WABOU HHRA, COCs were identified at each WABOU site.
Table 3-1 presents the groundwater COCs at the four WABOU groundwater sites. The
general criteria for the identification of groundwater COCs are presented below:
1. The contaminant creates a potential human health risk over 1 x 10*; or
2. The contaminant has a Hazard Index (HI) exceeding 1.0.
TABLE 3-1
Site Name
Building 755
Landfill 3
Building 905
Building 916
Maximum
Groundwater COC Concentration (pg/L)
1,1 -DCE (1.1-dichloroethene)
1 ,2-DCA (1 ,2-dichloroethane)
1,1,1-TCA (1,1,1-trichloroethane)
1 ,1,2-TCA (1,1,2-trichloroethane)
acetone
bromodichloromethane
methylene chloride
PCE (perchloroethene)
TCE
. aldrin
alpha-chlordane
heptachlor
heptachlor epoxide
heptachlor epoxide
PCB-1254
TCE
7,800
440
26,000
240
45,000
10
200
20
210,000
0.11
0.27
0.084
0.033
0.023
22
71
Human Health
Risk Value
2 x 10"2
1 x 10'4
Hazard Index (HI) = 3
5x10"5
HI = 4
3x 10'6
1 x 10~5
5 X 10'6
1 x 10'2
7 x 10'6
2x10'6
3 x 10'6
2x10'6
2X10'6
5x10'5
5x10'6
BDD-SFO/980960015.DOC (LNB209.DOC)
35
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PAHT II DECISION SUMMARY
The approach to evaluating pesticide concentrations in tte WABOU isbasec1 or^
sons with the concentrations found at other locations on Travis AFB. The WABOU RI used
SiSBaric Constituent Evaluation Methodology (Radian, 1996b) to determiru; whether
compounds detected in samples are naturally occurring or are contaminants from past
SS practices. Statistic^ analysis of the pesticide detections from non-pesticide sites
resulted in the establishment of WABOU reference concentrations for pesticides. More
detailed discussion of the WABOU pesticide evaluation is provided in Appendix I of the
WABOU RI report (CH2M HILL, 1997).
3.4 Summary
Groundwater at four out of 41 WABOU sites is contaminated with VOCs (Building 755 and
916XPCBS (Building 916), and pesticides (Building 905 and Landfill 3). Table 3-1 presents
the eroundwater contaminants at each site, the maximum concentrations, and the human
health risk values associated with each contaminant. No Sroun^aterCOEC^ere^-
fied in the WABOU. One additional groundwater site (Reservoir Facilities 1514/1518) was
transferred to the Compliance Branch of the Travis AFB Environmental Office for
disposition. The four WABOU sites were evaluated in the WABOU F5.
36
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PART (I DECISION SUMMARY
4 0 Summary of WABOU Groundwater Feasibility Study
r^?r^^^^^
1. Identify potential response actions, technologies, and process options to address the
potential risks in the WABOU
2. Screen the technologies and process options
3. Assemble feasible and appropriate remedial alternatives
4. Provide detailed evaluations of the remedial alternatives
5. Perform a comparative analysis of the alternatives
The FS can be divided into three main phases:
1 . The Initial Screening of Alternatives
2. The Detailed Analysis of Alternatives
3. The Comparative Analysis of Alternatives
4.1 Initial Screening of Alternatives
various site conditions.
most promising remedial alternatives.
The screening process is divided into the following seven steps:
level or range of levels is called a Prelinunary Cleanup Goal.
Step 2: Develop General Response Actions. General response actions describe the broad
range of actions that will satisfy the RAOs.
Step 3- Identify Potential Remedial Technologies and Process Options. There are many
potentia i : applicable technology types available to remediate all categories of contam,-
naSs under various site conditions. Some technologies have a proven record of perfor-
mTnL while others are promising but have not been tested under all field conditions.
GeneSuechnology types that can be used to implement a general response action are
re tod to ^reme^ial technologies. Specific technology types withm a remedial
37
RDD-SFO/980960015.DOC (LNB209.DOC)
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PART II DECISION SUMMARY
technology are called process options. An example of a remedial technology for an
administrative action is access restrictions; an example of a process option within this
remedial technology is fencing. Information on remedial technologies and process options
is acquired through data base searches and technical journal reviews. This review of all
potentially applicable technologies ensures that the best technologies are not overlooked
early in the FS process.
Step 4: Screen Process Options for Technical Implementability. In this step the evaluation
of technical implementability reduces the list of technology and process options. Technical
implementability refers to the ability of the remedial technology or process option to meet
an RAO. The result of this step is a list of technologies and process options that are capable
of addressing contaminant types found in the WABOU under existing site conditions.
Step 5: Technology Evaluation and Selection of Representative Process Options. The
process options that survived the above screening are evaluated for administrative
implementability, effectiveness and cost. Examples of administrative implementability are
the ability to obtain the necessary permits and the availability of necessary equipment and
workers to implement the process option. This evaluation further reduces the list of process
options to those that can be implemented, are effective in treating the contaminants in the
WABOU, and are not cost prohibitive.
Even after the above evaluations are completed, there may be a number of process options
that could be used to meet the RAOs. From the list of remaining process options within
each remedial technology, a representative process option is selected. The representative
process option is used to develop the alternatives, but the other equally promising process
options are retained.
Step 6: Assemble Remedial Alternatives. The representative process options are used to
assemble remedial alternatives that represent a range of general response actions
specifically for the WABOU sites.
Step 7: Screen Remedial Alternatives. In this final step of the ISA the remedial alternatives
are screened to ensure that they are protective of human health and the environment,
implementable and cost-effective. This is to verify that the combined groups of process
options meet these three criteria.
The ISA resulted in the development of seven groundwater remedial alternatives. Table 4-1
provides a brief description of these alternatives
4.2 Detailed Analysis of Alternatives
The purpose of the Detailed Analysis of Alternatives (DAA) is to analyze the alternatives
identified in the ISA and present the relevant information needed to select the appropriate
remedies. This is accomplished by evaluating each alternative against seven of the nine
criteria provided under CERCLA. Figure 4-1 defines the nine evaluation criteria. The other
two criteria (Community Acceptance and State Acceptance) are addressed in this Interim
Groundwater Record of Decision based on the acceptance of the WABOU Groundwater
Proposed Plan and the evaluation of comments received during the April 8,1998 - May 8,
1998 public comment period.
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PART II DECISION SUMMARY
TABLE 4-1
Interim Groundwater Remedial Alternatives
Remedial Alternative
Description
G1 - No Action
G2- Monitored Natural
Attenuation (MNA)
G3 - Containment/
Treatment/Discharge
G4 - Extraction/
Treatment/Discharge
G5 - Source Area and
Groundwater Extraction/
Treatment/Monitored
Natural Attenuation
G6 - Source Area
Extraction/Treatment/
Monitored Natural
Attenuation
This serves as a starting point for comparing the other alternatives. No groundwater
treatment takes place.
MNA is a groundwater treatment strategy that relies on naturally occurring processes to
prevent the spread of contamination. A major part of this strategy is the destruction of
contaminants into harmless by-products by subsurface microorganisms. Groundwater
monitoring is used to verify the effectiveness of this strategy.
This alternative is designed to prevent the migration of the groundwater contamination.
Groundwater is pumped from a series of extraction wells that are built near the leading edge
of the contaminant plume. The resulting hydraulic barrier removes the contaminated ground-
water before it can move past the extraction wells. The removed groundwater is treated
using activated carbon and is either discharged to Union Creek or used for irrigation.
This alternative uses the extraction wells as described in alternative G3. It also places
additional extraction wells in the more highly contaminated part of the plume in order to
actively treat the whole plume. The removed groundwater is treated and is either discharged
to Union Creek or used for irrigation.
This alternative applies only to Building 755 and is divided into three parts. The first part
uses a vacuum-enhanced groundwater technology, DPE. A DPE system uses a vacuum to
draw contaminated groundwater into an extraction well and at the same time lower the local
water table. Exposed pools of solvents would then evaporate, and the vacuum removes the
contaminated vapors. The water and vapors are cleansed in a treatment plant. This is
designed to remove the source of contamination at this site. The second part uses extraction
wells in the center of the plume to remove highly contaminated groundwater. The third part
uses MNA to treat the portion of the plume with lower contaminant concentrations. MNA is
described in Alternative G2.
This alternative also applies only to Building 755 and is divided into three parts. The first part
is the DPE system that is described above. The second part uses a reactive wall in the
subsurface to treat the contaminated groundwater as it passes through the wall. The third
part uses MNA technology to treat the portion of the plume with lower contaminant
concentrations. MNA is described in Alternative G2.
4.3 Comparative Analysis of Alternatives
In this final phase of the FS, the groundwater alternatives were evaluated based on how
well they meet the individual CERCLA criteria. This analysis identified the advantages and
disadvantages of each alternative, relative to each other, so that key tradeoffs could be used
to select the preferred alternatives at each site. A sensitivity analysis was included in the
Cost Comparative Analysis to determine how various uncertainties might affect the cost
estimates. The following subsections present summaries of the comparison of the strengths
and weaknesses of each alternative at each WABOU groundwater site.
Alternatives G5 and G6 were designed specifically for Building 755, because this is the only
WABOU groundwater site where pools of undissolved TCE are likely to be present beneath
the local water table. This conclusion is based on the high TCE concentrations detected at
the former sump area (source area).
Buildings 905 and 916 are evaluated together, because computer modeling of the ground-
water capture zones indicated that a single groundwater extraction well would be capable
of hydraulically containing the plumes at both buildings. As a result, Alternatives Gl, G2,
and G3 are the only alternatives that apply to these buildings.
ROD-SFO/98Q960015.DOC (LNB209.DOC)
39
-------
1. Overall Protection of
Human Health and the
Environment
Addresses whether a
remedy provides
adequate protection of
human health and the
environment and
describes how risks are
eliminated, reduced, or
controlled through
treatment, engineering
controls, or Institutional
controls.
S. Compliance with
Applicable or Relevant
and Appropriate
Requlremanta (ARARs)
Addresses whether a
remedy wffl meet an
ARARs [federal and
state environmental
statutes] and/or
provide grounds tor
invoking a waiver.
3. Long-term Effectiveness
and Permanence
Refers to toe ability of
a remedy to maintain
reliable protection of
human health and the
environment over
time, once dean up
goals have been met.
4. Reduction dTo«lelty,
Mobility, or Volume (TMV)
TnroughTnulmenl
Refers to Bie anticipated
ability of a remedy to
reduce the TMV of the
hazardous components
present at the cite.
5. Short-term Effectiveness
Addresses the period of
time needed to complete
Hie remedy, and any
adverse Impacts on human
health and the environment
that may be posed during
toe construction and
Implementation period, until
the clean up goals are
achieved.
e. knplamenlabyin;
Refers to the technical and
administrative feasibility ol
a remedy, including the
availability of materials and
services needed to carry
out a particular option.
7. Coat
Evaluates the
estimatsd capital and
operation and
maintenance costs of
each alternative.
S. State Acceptance
frufcates whettior. based on
Its review of the information,
the state concurs with, is
opposed to, or has no
comment on the preferred
alternative.
S. Community Acceptance
Indicates whether community
concerns are addressed by
the remedy and whether the
community has a preference
tor a remedy. Although public
comment ie an Important pad
of the final decision, EPA Is
compelled by law to balance
community concerns with all
ol he previously mentioned
criteria.
-•*. .-•"'.•ff'- • :
j*V »!;;;••/:*•'•';•;
NOTE
The nine criteria ara from the Guidance for Conducting Remedial
Investigations and Feasibility Studies under CERCLA (EPA. 1988)
and provide support (or the selected Remedial Alternative.
FIGURE 4-1
NINE EVALUATION CRITERIA
WEST/ANNEXES/BASEWIDE OPERABLE UNIT (WABOU)
WABOU QROUNDWATEH IROD
TRAVIS AIR FORCE BASE, CALIFORNIA
3443.802
•CH2MHILL-
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PART II DECISION SUMMARY
4.3.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment serves as a threshold determina-
tion that must be met by any alternative for it to be selected as a remedy. Each of the
groundwater alternatives, except for Alternative Gl (No Action), are protective of human
health and the environment.
4.3.2 Compliance with ARARs
Compliance with ARARs also serves as a threshold determination that must be met by any
alternative for it to be selected as a remedy. Each of the groundwater alternatives, except for
Alternative Gl (No Action), will comply with ARARs.
4.3.3 Long-Term Effectiveness and Permanence
The Long-term Effectiveness and Permanence criterion is a measure of two principal factors:
(1) the magnitude of residual risk; and (2) the adequacy and reliability of controls used to
manage treatment residuals. Each of the groundwater alternatives, except for Alternative
Gl (No Action), achieve some measure of long-term effectiveness and permanence. How-
ever, none of the alternatives as presently constituted achieve a high degree of effectiveness
and permanence at Building 755. Table 4-2 provides a summary qualitative evaluation of
the performance of each of the groundwater alternatives against this criterion on a site-by-
site basis.
4.3.4 Reduction of Toxicity, Mobility, or Volume Through Treatment
Each of the groundwater treatment alternatives, including Alternative Gl (No Action), will
achieve varying degrees of contaminant Reduction, Toxicity, Mobility, or Volume. How-
ever, Alternative Gl will not achieve reduction through treatment. Table 4-3 provides a
summary qualitative evaluation of the performance of each of the groundwater alternatives
against this criterion on a site-by-site basis.
RDD-SFO/980960015 (LNB209.DOC) 41
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PART II DECISION SUMMARY
TABLE 4-2
Groundwater Alternative
Site
Building 755
Landfill 3
Building 905
Building 916
G1
O
O
O
O
G2 G3 G4 G5 G6
Q ® ®
o •-"'-'
Legend: Relative performance of the
alternative at each site.
• Better satisfies criterion
® Moderately satisfies criterion
O Poorly satisfies criterion
Alternative not applicable at
this site
Alternative G1 - No Action
Alternative G2 - Monitored Natural Attenuation
Alternative G3 - Containment/Treatment/Discharge
Alternative G4 - Extraction/Treatment/Discharge
Alternative G5 - Source Area and Groundwater Extraction/
Treatment/Monitored Natural Attenuation
Alternative G6 - Source Area Extraction/Treatment/ Monitored
Natural Attenuation
TABLE 4-3
Summary of Comparative Analysis of Groundwater Alternatives - by Criterion Reduction of Toxicity, Mobility, and Volume
Site
Building 755
Landfill 3
Building 905
Building 91 6
G1
O
O
O
o
Groundwater Alternative
G2 G3 G4 G5 G6
O •
® ® •
. ® • . . -
® •
Legend: Relative performance of the
alternative at each site.
• Better satisfies criterion
$ Moderately satisfies criterion
O Poorly satisfies criterion
Alternative not applicable at
this site
Alternative G1 - No Action
Alternative G2 - Monitored Natural Attenuation
Alternative G3 - Containment/Treatment/Discharge
Alternative G4 - Extraction/Treatment/Discharge
Alternative G5 - Source Area and Groundwater Extraction/
Treatment/Monitored Natural Attenuation
Alternative G6 - Source Area Extraction/Treatment/ Monitored
Natural Attenuation
RDD-SFO/980960015 (LNB209.DOC)
42
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PART II DECISION SUMMARY
4.3.5 Short-Term Effectiveness
The Short-term Effectiveness criterion is a measure of the protection afforded by each alterna-
tive during the construction and implementation process. As such, the time until the reme-
dial action objectives are achieved is an important component of the criterion. Each of the
groundwater alternatives, except for Alternative Gl {No Action), is effective in the short
term to some degree. Table 4-4 provides a summary qualitative evaluation of the ground-
water alternatives against this criterion on a site-by-site basis.
TABLE 4-4
c
Site
Building 755
Landfills
Building 905
Building 916
G1
O
O
O
O
Groundwater Alternative
G2 G3 G4 G5 G6
O
® ® •
£& ^V <_ • —
oft ' ' ' ^k * *
Legend: Relative performance of the
alternative at each site.
• Better satisfies criterion
® Moderately satisfies criterion
O Poorly satisfies criterion
Alternative not applicable at
this site
Alternative G1 - No Action
Alternative G2 - Monitored Natural Attenuation
Alternative G3 - Containment/Treatment/Discharge
Alternative G4 - Extractionn"reatment/Discharge
Alternative G5 - Source Area and Groundwater Extraction/
Treatment/Monitored Natural Attenuation
Alternative G6 - Source Area Extraction/Treatment/ Monitored
Natural Attenuation
4.3.6 Impiementability
The Implementability criterion evaluates the technical and administrative difficulties
associated with implementing each alternative. An important component of technical
implementability is consideration of the reliability of the technology. Each of the
groundwater alternatives are implementable. Table 4-5 provides a summary qualitative
evaluation of the groundwater alternatives against this criterion on a site-by-site basis.
RDD-SFO/980960015.DOC (LNB209.DOC)
-------
PART II DECISION SUMMARY
TABLE 4-5
Site
Building 755
Landfills
Building 905
Building 916
G1
O
O
O
O
Groundwater Alternative
G2 G3 G4 G5 G6
0^ ^h tfh ^P ^p
• • •
• • .
Q\ , . ^k _
Legend: Relative performance of the
alternative at each site.
• Better satisfies criterion
© Moderately satisfies criterion
O Poorly satisfies criterion
Alternative not applicable at
this site
Alternative 31 - No Action
Alternative G2 - Monitored Natural Attenuation
Alternative G3 - Containment/Treatment/Discharge
Alternative G4 - Extraction/Treatment/Discharge
Alternative G5 - Source Area and Groundwater Extraction/
Treatment/Monitored Natural Attenuation
Alternative G6 - Source Area Extraction/Treatment/ Monitored
Natural Attenuation
4.3.7 Cost
Table 4-6 presents the total project cost estimates for each groundwater alternative at each
site. These Cost criterion estimates are a total of the site-specific capital and annual
Operations and Maintenance (O&M) cost estimates for implementing the alternative. The
annual O&M cost estimates for Alternatives G2, G3, and G4 are based on a 30-year period of
groundwater treatment plant operation. The annual O&M cost estimates for Alternatives
G5 and G6 are based on a 10-year period of DPE operation and a 30-year period of
groundwater treatment.
Detailed cost summary tables are provided in Appendix A of the West/Annexes/Basewide
Operable Unit Feasibility Study, 60" Air Mobility Wing, Travis Air Force Base (CH2M HILL,
1998). The assumptions that were used to create the site-specific cost estimates are described
in Section 8 of the above-cited document. These assumptions are divided into general
project assumptions, such as well construction details and monitoring frequency, and site-
specific assumptions, such as the selected treatment technology and the number of extrac-
tion and monitoring wells for each site.
RDD-SFO/980960015.DOC (UB209.DOC)
44
-------
PART II DECISION SUMMARY
TABLE 4-6
Cost Estimates for WABOU Groundwater Remedial Alternatives
Site-Specific Total Project Cost Estimate ($)
Landfill 3 Buildings 905/916
G1 - No Action
G2 - Monitored Natural Attenuation
G3 - Containment/Treatment/
Discharge
G4- Extraction/Treatment/ Discharge
0
510,300
929,700
2,277,000
0
565,400
582,300
819,800
0
532,800
568,100
-
G5 - Source Area and Groundwater 4,950,000
Extraction/Treatment/Monitored
Natural Attenuation
G6 - Source Area Extraction/ 7,406,000
Treatment/Monitored Natural
Attenuation ___^_
4.4 Conclusion
The Comparative Analysis did not recommend the implementation of a specific alternative
for each WABOU site. It described the overall performance and cost of each groundwater.
alternative at each site. The paragraphs below summarize the findings of this analysis.
At Building 755, Alternatives G3 through G6 were all comparable in the way they satisfy
the criteria. Alternative G4-Extraction/Treatment/Discharge appeared to do a slightly
better job at meeting the criteria, because it achieves capture of the contaminated ground-
water at this site faster than the other alternatives. The main drawback with this alternative
is that it does not address the source of the contamination. Suspected solvent pools beneath
this site may release dissolved contaminants to the groundwater for a long time.
Alternatives G5 and G6 address the source of the contamination, but rely on MNA to
remediate the downgradient end the plume. Without the data needed to evaluate the
capability of local natural attenuation processes, it was necessary to use conservative
assumptions in the computer modeling which indicated that natural attenuation would
need more than 100 years to remediate the contamination.
At Landfill 3, Alternative G4-Extraction/Treatment/Discharge was evaluated to best satisfy
the criteria. Alternative G4 was judged superior to Alternative G3 because it included
extraction at the source and thereby captured the plume more quickly. Pump-and-treat
options were considered superior to MNA mainly because of lack of natural attenuation
data. Alternatives G5 and G6 are not applicable at Landfill 3.
At Buildings 905 and 916, Alternative G3-Contamment/Discharge/Discharge was evalu-
ated to best satisfy the criteria. Alternative G2 (MNA) was the only viable alternative to
compare to Alternative G3, and Alternative G2 does not compare well because of the lack of
natural attenuation data at these sites. Alternatives G4, G5, and G6 did not apply at these
sites.
RDD-SFO/980960015.DOC (u*209.DOC) . 45
-------
PART II DECISION SUMMARY
5.0 Interim Groundwater Remedial Actions
Travis AFB has selected interim groundwater remedial actions for the four WABOU
groundwater sites. Each of the selected remedies will protect human health and the
environment and comply with ARARs. They are effective at reducing contamination, are
implementable and cost-effective, and are acceptable to the public and the State of
California. These decisions are based on the environmental conditions and the nature and
extent of groundwater contamination found at each site. They are also based on the
technology and U.S. EPA criteria evaluations from the WABOU FS. The following
subsections present these selected actions and the rationale for the decisions.
5.1 Building 755 (DP039)
Alternatives G5—Source Area and Groundwater Extraction/Treatment/Monitored
Natural Attenuation and G3—Containment/Treatment/Discharge are the selected
alternatives for Building 755. The Air Force believes that a combination of these two
alternatives offers the best opportunity to achieve the groundwater cleanup in an efficient
and cost-effective manner.
5.1.1 Alternative G5—Source Area and Groundwater Extraction/Treatment/ Monitored
Natural Attenuation
Alternative G5 is a three-part strategy that starts with an aggressive approach toward
removing the groundwater contamination source. The former battery acid neutralization
sump was used for the disposal of chlorinated solvents, and the high solvent concentrations
found in the former sump area (210,000 ppb of TCE) are indicative of the presence of dense
non-aqueous phase liquid (DNAPL) beneath the water table. Since solvents tend to dissolve
into water very slowly, it is likely that the groundwater alternatives that rely on standard
pump-and-treat methods would take a very long time to reduce these high solvent
concentrations.
The Air Force will construct a DPE system to remove the highly concentrated VOC
contamination beneath the former sump area. A DPE system applies a vacuum to the
subsurface soil layers and draws contaminated water into the extraction well, thereby
lowering the local water table in the vicinity of the solvent pools. The vacuum also stirs up
the air between the soil particles. Any undissolved solvent pools that are exposed to the air
by the lowered water table will evaporate, and the vacuum will draw contaminated vapors
out of the extraction well. Air is more efficient in removing solvents than water, because the
solvents evaporate quickly. So, the goal of using a DPE system is to remove the source area
in less time than by using standard groundwater pump-and-treat methods.
The second part of the cleanup consists of the installation of at least one extraction well in
the central portion of-the groundwaterplume. This will reduce the high concentrations of
dissolved solvents and the potential risk that they pose. The actual number and placement
of the well(s) will be determined after taking into account the effect of the DPE system on
the groundwater plume. Figure 5-1 shows the conceptual design of Alternative G5 at
Building 755.
To ensure that the plume will not migrate any further, the Air Force has added Alternative
G3 to the Alternative G5 cleanup strategy. Alternative G3 uses a row of extraction wells
RDD-SFO/980960015.DOC(LNB209.DOC) 46
-------
PART II DECISION SUMMARY
around the plume to prevent its further expansion. Figure 5-2 presents the conceptual lay-
out of this alternative. The Air Force will then test the MNA component of Alternative G5
through the collection of analytical data in accordance with U.S. EPA and California guide-
lines. This data will be used to determine whether the subsurface microorganisms are active
and capable of breaking down the contaminants and preventing the spreading of the
plume.
The implementation of the groundwater treatment strategy at Building 755 will be designed
to remove the maximum amount of contamination as quickly as possible and not promote
the migration of highly contaminated groundwater to areas with lower contaminant con-
centrations. As a result, the Air Force will use a phased approach to build the treatment
system and collect groundwater data. In general, the remedial activities will start at the
source area (former sump area) and continue in the downgradient direction.
5.1.1.1 Phase 1—OPE Construction
The groundwater remedial actions will begin with the construction and operational testing
of the DPE system. This system will be designed to lower the local water table and volatilize
the DNAPL pools that are exposed to the air. The objective of this phase is to remove the
source of the existing plume and thus prevent the future generation of contaminated
groundwater.
One important aspect of the DPE system operational test is the measuring of the system's
radius of influence. Monitoring wells and piezometers will be adapted and installed to
measure the impact of the vacuum on the downgradient strata and the local groundwater
flow. This information is needed to properly design and place the downgradient extraction
well(s) in the next phase.
Another activity in this phase will be the data collection for the evaluation of MNA in the
downgradient portion of the plume. Monitoring wells will be installed throughout the
plume, and groundwater sampling and analysis will take place. The Air Force anticipates
that the operational testing of the DPE system will have no impact on this groundwater
sampling effort. The first (and possibly second) round of data collection will serve as a
baseline for existing environmental conditions and the status of the plume. Subsequent
sampling rounds will be used to demonstrate any changes to the plume, either by MNA or
by the engineered activities.
5.1.1.2 Phase 2—Groundwater Extraction
Once the DPE system is fully functional, the first groundwater extraction well will be
installed. The purpose of this well is to remove the highly contaminated dissolved portion
of the plume. The placement of this well will be based on the calculated capture zone of the
well, taking into account the impact of tine operational DPE system. The piping system will
be designed to allow for flexibility in case additional downgradient extraction wells are
needed. It is possible that the decision for additional extraction wells may be made once the
DPE system is operational, depending on the evaluation of the collected data.
Once the groundwater extraction well(s) is/are installed, data collection will continue to
determine the revised radius of influence of the overall extraction system. An attempt will
be made to design and place the installed monitoring wells so that they can be used for both
system monitoring and natural attenuation data collection.
RDD-SFO/980960015.DOC (LNB209.DOC) 47
-------
JULY 1996
GROUNDWATER
FLOW DIRECTION
\ \
! U \\,,'i /
rT^RrAYlfEUrPLANT (
!/ V "\ UNION CREE
I W k
'Jr^=
LEGEND
SB EXISTING MONITORING WELL (MW)
A PROPOSED SHALLOW MONITORING WELL
• PROPOSED DEEP MONITORING WELL
® PROPOSED EXTRACTION WELL
—x— FENCE
I I BUILDINGS
' WEST BRANCH OF UNION CREEK
ROADS
— _ — TCE CONCENTRATION CONTOURS (pg/L)
• • CAPTURE ZONE
PIPELINE
0 135 270 FEET
SCALE IS APPROXIMATE
NOTE
MCL FOR TCE IS 5 pg/L.
FIGURE 5-1
ALTERNATIVE G5 —
SOURCE AREA AND GROUNDWATER EXTRACTION/
TREATMENT/ MONITORED NATURAL ATTENUATION
CONCEPTUAL DESIGN AT BUILDING 755
WEST/ANNEXES/BASEWIDE OPERABLE UNIT (WABOU)
WABOU GROUNDWATER (ROD
TRAVIS AIR FORCE BASE, CALIFORNIA
CH2MHILL-
-------
JULV 1996
GROUNDWATER
FLOW DIRECTION
LEGEND
« EXISTING PIEZOMETER (SB)
B EXISTING MONITORING WELL
-------
PART II DECISION SUMMARY
5.1.2 Alternative G3—ContainmentfTreatment/Discharge
The Air Force added this alternative to the Alternative G5 treatment strategy to comply
with specific State ARARs that are concerned with groundwater and plume migration. I he
purpose of Alternative G3 is to prevent plume migration by constructing a hydraulic bamer
of extraction wells near the leading edge of the plume. By definition, containment is
achieved when groundwater along a flow line that originates at any location within the
plume, at any depth in the aquifer, is moving toward and into an extraction well.
5.1.2.1 Phases-Installation of the Alternative G3 Wells '
In this last construction phase the extraction wells on the outer downgradient edge of the
plume will be installed. The number and placement of these wells will be based on the
revised calculated capture zone of the Alternative G5 system that is already in operation.
Figure 5-2 shows the conceptual design of Alternative G3 at Building 755.
There is a possibility that the Air Force will look at innovative technologies for the
migration control wells. For example, researchers at the University of California, Davis
have developed a multistage in-well aeration system that is designed to remove VOCs from
eroundwater in an effective and inexpensive manner. The regulatory agencies will be
involved in any treatability study that may be conducted to demonstrate the abilities of
these types of innovative systems.
5.2 Landfill 3 (LF008)
Alternative G^Extractionnreatment/Discharge is the selected alternative for Landfill 3.
This alternative uses standard pump-and-treat technology. Three extraction wells are
placed around the pesticide trenches to prevent contaminated groundwater from moving
away from the site. An additional extraction well is placed in the center of the pesticide
trenches to remove contaminated groundwater from beneath the trenches. Figure 5-3 shows
the conceptual design of Alternative G4 at Landfill 3.
This is the most aggressive cleanup strategy for this site. The older pesticides at this landfill
are resistant to natural breakdown processes, so Alternative G2 may not be successful in
stopping future plume migration. Alternative G3 would eventually meet cleanup goals, but
it is not as effective at removing contamination and may have a longer cleanup time.
Before the groundwater cleanup can begin, the pesticide-contaminated debris and soil in
the trenches that contribute to the groundwater contamination need to be removed. This
portion of the site remediation is discussed in greater detail in the WABOU Soil Proposed
Plan. It is possible that the soil remediation may not be scheduled prior to the start of the
Alternative G4 treatment plant construction due to programming or funding limitations. In
this case, the Air Force and the regulatory agencies will review all schedule options and
select the most appropriate approach to conducting the soil and groundwater remedial
actions without causing-a significant project cost increase.
50
RDD-SFO/980960015.DOC (UJ6209.00C)
-------
JULY 1996
GROUNDWATER
FLOW DIRECTION
>X
U r-
V
\_ XSJ^ * * * *
TO BUILDING
TREATMENT
SCALE IS APPFWXIMAT6
LEGEND
H! EXISTING MONITORING WELL (MW)
ffi PROPOSED EXTRACTION WELL
* PROPOSED SHALLOW MONITORING WELL
• PROPOSED DEEP MONITORING WELL
—*— FENCE
CAPTURE ZONE
PIPELINE
AREA OF GROUNDWATER CONTAMINATION
FIGURE 5-3
ALTERNATIVE G4 —
EXTRACTION/TREATMENT/DISCHARGE
CONCEPTUAL DESIGN AT LANDFILL 3
WEST/ANNEXES/BASEWIDE OPERABLE UNIT (WABOU)
WABOU GROUNDWATER IROD
TRAVIS AIR FORCE BASE, CALIFORNIA
CH2MHILL •
-------
PART ll DECISION SUMMARY
ft
5.3 Buildings 905 (SS041) and 916 (SD043) W
Alternative GS-Containment/Treatment/Discharge is the selected alternative for
Buildings 905 and 916. As mentioned in previous sections, these sites are discussed
togete, because the two buildings are located close together, and a groundwater modeling
computer program used .in the W ABOU FS predicted that a single extraction well would
capture the contaminated groundwater from both sites.
The groundwater contaminants found beneath Buildings 905 and 916 are TCE PCB-1254,
and pesticides. The older pesticides at Building 905 and the PCB1254 at Building 916 are
resistant to natural degradation processes, so Alternative G2 may not be successful in
stopping future plume migration.
Since the results of the computer modeling indicate that Alternative G3 is capable of
capturing the groundwater plumes from both sites with only one extraction well, it is the
seleSLrrSive. Figure 5-4 presents the conceptual layout of Alternative G3 at Buildings
905 and 916.
5.4 Treatment
For Building 755, treatment of the vapor-phase VOCs genef*edKfro^
be conducted at an onrsite Vapor-Phase Granular Activated Carbon (VGAC)
plant. Treatment of the extracted groundwater will be accomplished locally using a Liquid-
Phase Granular Activated Carbon (LGAC) treatment system or through a centrally located
groundwater treatment system that would be capable of treating contaminated
groundwater from multiple sites.
For Landfill 3 and Buildings 905 and 916, treatment of the extracted groundwater will be by
LGAC locally or by a centrally located groundwater treatment system that would be
capable of treating contaminated groundwater from multiple sites.
The rationale for the selection of the treatment technologies mentioned above is found in
Appendix C of the West/Annexes/Basewide Operable Unit Feasibility Study, 60? Air Mobility
Wing, Travis Air Force Base, California (CH2M HILL, 1998).
The Air Force developed Interim Cleanup Goals for the WABOU to measure the perfor-
mance of each groundwater treatment system. These goals are chemical concentrations that
are defined as protective of human health and the environment. These goals are similar to
the final cleanup levels that will be presented in the basewide groundwat erROD but,are
not enforceable standards. Table 5-1 presents the interim cleanup goals for the WABOU
groundwater sites.
The Air Force will treat the extracted groundwater until contaminants have been reduced to
the discharge standards presented in Section 6.0.
52
RDD-SFO/9B0960015.DOC(LNB209.DOC) .
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PART II DECISION SUMMARY
TABLE 5-1
Site Name
Building 755
(DP039)
Landfill 3
(LF008)
Building 905
(SS041)
Building 91 6
(SD043)
Groundwater
COC
1,1-DCE
1.2-DCA
1,1,1-TCA
1,1,2-TCA
acetone
bromo-
dichloromethane
methylene chloride
PCE
TCE
aldrin
alpha-chlordane
heptachlor
heptachlor epoxide
heptachlor epoxide
PCB-1254
TCE
interim
Cleanup Goal
(WJ/L)
6
0.5
0.5
0.5
5110
100
5
5
5
0.023
0.1
0.01
0.01
0.01
1.02
5
California
MCL"
(U9/L)
6
0.5
0.5
0.5
-
100
5
5
5
-
0.1
0.01
0.01
0.01
-
5
Federal MCL
(H9/L)
7
5
5
5
-
100
5
5
5
-
2
0.4
0.2
0.2
-
5
WABOU
Reference
Concentration6
NAC
NA
NA
NA
NA
NA
NA
NA
NA
0.023
0.02
0.02
O.O24
0.024
NA
NA
3 MCL = Maximum Contaminant Level (RWQCB, 1995) for drinking water
b The discussion of the WABOU reference concentration is found in Section 3.3.
c NA - Not Applicable
5.5 Treated Water Disposal
In general, treated water from the groundwater treatment systems at all four WABOU
groundwater sites will be used as beneficial use water during the dry summer months and
will be discharged into Union Creek during the wet winter months. Three possible bene-
ficial uses of the treated water are landscape irrigation of installation grassland, industrial
uses such as aircraft or car washing, and dust suppression for construction activities. Travis
AFB will use most of the reused treated groundwater for landscape irrigation. Travis AFB
will discharge treated groundwater that cannot be beneficially used to the sanitary sewer
operated by the Fairfield-Suisun Sewer District, if feasible, or to Union Creek. At times
treated water may need to be discharged into Union Creek during the dry summer months
if the need arises.
RDD-SFO/9B0960015.DOC (UB209.DOC)
53
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JULY 1880
GROUNDWATER
FLOW
DIRECTION
DRAINAGE
CHANNEL
BOUNDARY
FORMER TRANSFORMERsPAD
AREAS OF
\ GROUNDWATER
CONTAMINATION
FIGURE 5-4
ALTERNATIVE G3 —
LEGEND
© EXISTING PIEZOMETER (SB)
B EXISTING MONITORING WELL (MW)
A PROPOSED SHALLOW MONITORING WELL
• PROPOSED DEEP MONITORING WELL
© PROPOSED EXTRACTION WELL
—K— FENCE
• DRAINAGE
—— CAPTURE ZONE
'• PIPELINE
.
CONCEPTUAL DESIGN AT BUILDINGS 905/916
WEST/ANNEXES/BASEWIDE OPERABLE OIW
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PART II DECISION SUMMARY
The NEWIOU Groundwater RD/RA Plan uses the Treated Groundwater Use Plan to
strategize the specific use of treated groundwater and to estimate irrigation and industrial
needs for the Base. This Plan also contains a decision matrix that outlines the rationale and
method for treated groundwater discharge at Travis AFB. The WABOU addendum to this
Plan will follow this approach.
The volumes of treated groundwater discharged to Union Creek will be estimated and
measured during the RD/RA phase to ensure there are no adverse impacts to Union Creek.
Groundwater extraction and treatment will take place in phases, which will gradually
increase the amount of treated water available for use. By 1999, Travis AFB might extract
and treat approximately 413 gallons per minute (gpm) from both NEWIOU and WABOU
groundwater sites. The Treated Groundwater Use Plan presents the assumptions used to
derive this rate.
Before the treated water reaches Union Creek, it is sampled and analyzed to verify that it
meets appropriate water quality standards. The Air Force will meet the discharge"
requirements for treated groundwater as presented in Section 6.0. Additional NPDES
substantive requirements for sampling, monitoring, and reporting will be established for
each new discharge: These requirements will be based on the descriptions of treatment
units with schematic drawings and design criteria, operation and maintenance procedures,
results of chemical analyses of untreated groundwater (influent) at each site, projected
maximum concentrations, projected flow rates, topographic maps showing exact locations
of proposed discharges, and other appropriate data. These NPDES substantive
requirements will be presented in each site-specific WABOU RD/RA work plan. Discharges
of treated water to Union Creek are subject to approval by the SFBRWQCB.
5.6 Land Use Restrictions
The Air Force has land use restrictions in place at the four WABOU groundwater sites.
These administrative actions restrict the use of onbase groundwater from these
contaminated sites. Travis AFB does not currently use its onbase groundwater for drinking
water. These actions also restrict soil excavation and other subsurface work where the
excavation worker will encounter contaminated groundwater or vapors. These subsurface
activities are only allowed after environmental and worker safety control measures are in
place. Travis AFB uses its digging permit program to coordinate, and if necessary, restrict
contractor and Base personnel access to contaminated areas. In addition, Travis AFB will
amend its General Plan to document additional land use restrictions, once the final remedial
actions are selected in the basewide groundwater ROD. A detailed description of the
existing land use restrictions at the four WABOU groundwater sites will be included in the
addendum to the NEWIOU Groundwater RD/RA Plan.
Groundwater beneath Travis AFB is not used to provide potable water to the Base; so the
Air Force does not need a contingency plan to replace the onbase water supply.
5.7 Groundwater Monitoring
Groundwater monitoring will be used at all WABOU groundwater sites to document the
effectiveness of the interim actions. The details of the groundwater monitoring strategy at
each site, such as monitoring well locations and sampling interval, will be presented in the
site-specific RD/RA work plans. Groundwater monitoring of each treatment system will be
RDO-SFCW980960015.DOC (UJB209.DOC) ' 55
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PART!! DECSON SUMMARY
initiated during the RA and will be transferred to the Travis AFB Groundwater Sampling
and Analysis Program (GSAP) after a period of at least one year.
5.8 Statutory Determinations
This section discusses the applicability and compliance of the following statutory
determinations:
Protectiveness
Applicable or Relevant and Appropriate Requirements
Cost-Effectiveness
Use of Permanent Solutions, Alternative Treatment, or Resource Recovery Technologies
Preference for Treatment as a Principal Element
State and Community Acceptance
5.8.1 Protectiveness
These selected remedies are protective of human health and the environment in the short
term and are designed to increase protection until the final basewide groundwater ROD is
signed. They achieve protection by removing source areas of contamination that can cause
the degradation of the local groundwater for a long time. They also prevent the migration of
contaminated groundwater beyond the current plume boundaries.
5.8.2 Applicable or Relevant and Appropriate Requirements
The selected remedies comply with state and federal ARARs. The groundwater ARARs are
presented in Section 6.0.
5.8.3 Cost-Effectiveness
The technologies selected in implementing the groundwater remedial actions at each site
are the most cost-effective technologies that can meet the WABOU Remedial Action
Objectives. The details of the technology selection are presented in Appendix C of the
WABOU FS.
5.8.4 Use of Permanent Solutions, Alternative Treatment, or Resource Recovery
Technologies
The selected remedies utilize permanent solutions to the potential threats posed by
groundwater contamination at each site to the maximum extent practicable. The use of
innovative technologies such as DPE is designed to remove large quantities of contaminant
mass before they are able to dissolve into the local groundwater. Standard pump-and-treat
systems will be used to prevent plume migration and remove dissolved contamination.
MNA of dissolved chlorinated solvents is an innovative and cost-effective treatment
strategy that may be capable of remediating contaminated groundwater.
5.8.5 Preference for Treatment as a Principal Element
Each remedy will effectively use active treatment to address the principal potential threats
posed by contaminated groundwater. The evaluation of MNA, an iri-situ treatment technol-
ogy, is included as a component of the selected alternative for Building 755. The Air Force
will use the groundwater treatment systems at each WABOU site to maximize contaminant
W»-SFQS80960015.DOC(lNB209.00C) 56
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PART II DECISION SUMMARY
removal from the groundwater to the extent practicable. The Air Force will also determine
whether MNA is an appropriate treatment technology for Building 755.
5.8.6 State and Community Acceptance
The State of California (DTSC and SFBRWQCB) concurs with the Air Force and the
U.S. EPA in the selection of the interim actions described in this section for the WABOU
groundwater sites.
Based on the comments received during the April 8,1998 to May 8,1998, public comment
period, the public has no preference of alternatives. The public comments received and the
Air Force response is provided in Part HI (Responsiveness Summary).
5.9 RD/RA Implementation and Schedule
The Air Force will implement the RD/RA in accordance with this IROD. In accordance with
the Travis AFB FFA, the Air Force will present a schedule for completing and submitting
the site-specific RD/RA work plans and RDs to the regulatory agencies within 21 days of
signing the WABOU Groundwater IROD.
The WABOU RD/RA schedule is based on the Travis AFB IRP Priority Model. This model
is a planning tool used by Travis AFB to prioritize funding and schedule remedial actions
for IRP sites. Factors considered in this model include human health risk, offbase migration,
ecological risk, public interest, MNA, mass of contaminants, groundwater concentration,
capital cost, project execution, and projected funding levels.
Previously the Air Force created a NEWIOU Groundwater Remedial Design/Remedial
Action Plan to describe the overall rationale for treatment and discharge of extracted
groundwater for all NEWIOU groundwater sites. It also included the NEWIOU RD/RA
schedule and a decision matrix for selecting the treatment technologies at each NEWIOU
site. The Air Force will add an addendum to this work plan to include a detailed
description of the treatment and discharge of extracted groundwater for the WABOU sites.
The addendum will also include the WABOU RD/RA schedule. The Air Force will provide
an opportunity for public participation during the Remedial Design phase.
Previously, the Air Force created a NAAP to provide the methodology used to evaluate the
potential use of MNA at NEWIOU sites. The Air Force will add an addendum to the NAAP
to include a description of the approach to be used for the evaluation of the MNA
component of Alternative G5 at Building 755.
In addition to the addendum to the Groundwater NEWIOU RD/RA Plan, the Air Force will
prepare a site-specific RD/RA work plan for each WABOU groundwater site. The site-
specific RD/RA work plans will present the placement of monitoring wells, groundwater
monitoring protocols and frequency, and procedures to determine whether plume migra-
tion above water quality objectives is occurring. The regulatory agencies will review each of
the site-specific WABOU RD/RA work plans. If a contingency action is necessary to control
migration, the Air Force will request funding and implement a contingency action as soon
as funding becomes available.
If the RD investigation reveals an interaction between groundwater and a preferential
pathway, then an appropriate remedial action will be proposed for the site and documented
in an amendment to this Groundwater IROD. There is no potential for contaminated
fWD-SFai9e096001SJX)C(U«20e.OOC) 57
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PART II CESSION SUMMARY
groundwater to migrate along storm and sanitary sewer lines, based on a comparison of the
highest measured level of the local water table with the location and depth of the local
sanitary and storm sewer lines the WABOU. However, if future data collection suggests
that contaminated groundwater has migrated to an area where interaction with preferential
pathways is likely/ the Air Force will investigate the potential interaction during the RD. At
locations where the Air Force has verified the migration of contaminated groundwater to
the storm sewer or Union Creek, the Air Force will expand the interim remedial action to
control migration. The Air Force will continue to monitor the effectiveness of its interim
actions to ensure that plume migration is controlled.
The Air Force will implement interim groundwater remedial actions as described in this
WABOU Groundwater IROD. The Air Force will monitor all sites and will measure the
change in contaminant concentrations. The Air Force will utilize the monitoring results to
evaluate the potential for using the MNA component of Alternative G5 at Building 755. The
Air Force and regulatory agencies will periodically review the analytical and performance
data from these actions to verify their effectiveness and the need for additional action(s).
The Air Force and regulatory agencies will hold a formal program review after the IROD is
signed and after sufficient analytical and performance data have been collected. The
purpose of the program review will be to determine the final basewide remedial actions and
cleanup levels mat are technically and economically feasible for each groundwater site at
Travis AFB.
5.10 Documentation of Significant Changes
There have not been any significant changes to the selected remedies since the Air Force
submitted the WABOU Groundwater Proposed Plan for public comment on April 8,1998.
RDO^Ofle0960015.DOC(LNB209.00C) 56
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PART II DECISION SUMMARY
6.0 List of Applicable or Relevant and Appropriate
Requirements and Performance Standards
6.1 Overview
Under CERCLA, remedial actions designed to dean up or abate contaminants in the
groundwater or in soils, must be designed, constructed and operated to comply with all
federal and more stringent state ARARs. ARARs include both federal requirements under
any federal environmental law and state requirements under state environmental or
facility-siting laws which are more stringent than federal requirements and that have been
identified by the State of California in a timely manner.
Applicable requirements are those cleanup standards, standards of control, and other
substantive environmental protection requirements, criteria, or limitations promulgated
under federal environmental or state environmental or facility siting laws that specifically
address a hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstance at a CERCLA site. Relevant and appropriate requirements include those mat,
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. If a given requirement is both relevant and appropriate
to a particular site, it constitutes a valid legal requirement for that site. A requirement must
either be 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 non-promulgated standards, criteria, guidance, and to be considered
(TBC) advisories are identified as additional performance standards in the ROD.
In general, onsite actions need to comply only with the substantive aspects of these
requirements, not with corresponding administrative requirements (such as, but not limited
to, permits, recordkeeping, and reporting).
All laws and statutes identified as ARARs for a particular site or action must be considered
and applied during the design, construction, and operation of any remedial action at the
particular site. ARARs are identified on a site-specific basis from data and information
concerning that site. Data and information concerning the objectives of site remediation,
specific actions that are being considered as remedies at that site, the hazardous substances
located upon the site, the physical and geological characteristics of the site, and the poten-
tial human and ecological receptors at or near the site must be analyzed and considered in
order to properly identify ARARs at a particular site. All federal and more stringent state
requirements that address or impact any of these conditions must be included as site
ARARs.
The three categories of ARARs are described below:
Chemical-Specific ARARs establish numerical values or provide methodologies which,
when applied to site-specific conditions, result in the establishment of numerical values.
The Air Force developed these ARARs by identifying the contaminants at a site which pose
a threat to human health or the environment and must be remediated. Chemical-specific
ARARs determine acceptable concentrations of specific hazardous substances, pollutants,
RDD-SFCV9e0960015.DOC (LNB209.DOC) 59
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P/urrll DECISION SUMMARY
and contaminants in the environment and establish the levels to which the soil or
groundwater at the affected site must be cleaned or restored in order to protect human
health and the environment. Chemical specific ARARs also establish the levels at which
certain actions must be taken while transporting, treating, or storing hazardous wastes
recovered during remediation..
Location-Specific ARARs are designed to protect the unique characteristics of the site or
other areas potentially affected by site activities during the design, construction, or
operation of remedial activities. Location-specific ARARs place restrictions on the concen-
tration of hazardous substances or the conduct of activities solely because the site occurs in,
or may affect, a special location. Some examples include the protection of wetlands and
vernal pools; protection of endangered or threatened species and their habitats; and the
protection of fish and game from unauthorized taking.
Action-Specific ARARs are technologically or activity-based requirements or limitations on
the particular remedial actions at the site. Some examples include prohibitions or restric-
tions against the discharge of chemicals or contaminants to the air, water, or soil and the
proper transfer, treatment or storage of chemicals and contaminants.
6.2 ARARs Identification, Development, and Evaluation
6.2.1 Methodology
As lead agency, the Department of the Air Force has performed each of the following
actions consistent with CERCLA and the NCP:
Identified federal ARARs for each remedial action alternative addressed in the WABOU FS,
taking into account site-specific conditions found in the WABOU.
Reviewed potential state ARARs identified by the state in order to determine whether each
potential ARAR satisfied CERCLA and NCP criteria that must be met in order to qualify as
state ARARs.
Evaluated and compared federal ARARs and their state counterparts in order to determine
which state ARARs are more stringent or are in addition to the federal ARARs.
Reached a conclusion as to which federal and state requirements were the most stringent
ARARs for each alternative.
6.2.2. Solicitation, Identification, and Evaluation of State ARARs
The Department of the Air Force followed the procedures of the process set forth in 40 CFR
Section 300.515 and the Travis AFB FFA for remedial actions in seeking state assistance in
identification of state ARARs.
The CERCLA, NCP, and FPA requirements for remedial actions provide that the lead
federal agency request that the state identify chemical-specific and location-specific state
ARARs. The Air Force requested chemical-, location-, and action-specific ARARs from
DTSC on 20 February 1997. The request letter included as an attachment the ARARs tables
developed during the NEWIOU FS. These tables were developed using responses from:
• California Integrated Waste Management Board
• Department of Toxic Substances Control Board
RDD-SFCV980960015.DOC (INB209.DOC)
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PART II DECISION SUMMARY
• State Water Resources Control Board
• California Regional Water Resources Control Board
• Bay Area Air Quality Management District
• California Department of Fish and Game
With few exceptions, the .site conditions at both operable units are similar, so this approach
was used to simplify the WABOU ARARs selection process for bom the state and the Air
Force. The tables were made available so that the state could identify additional require-
ments, if any, to be included as ARARs, or identify those requirements which were not
applicable to the WABOU. The state did identify additional requirements that address
radiological remediation sites and actions.
During the review and analysis of ARARs identified by the state, and following consider-
able discussion with the representatives from the various state agencies, many of the
requirements identified by the state as potential ARARs were determined to be valid
ARARs by the Air Force. These ARARs are presented in mis section of the WABOU Interim
Groundwater ROD. However, there are a few issues between the Air Force and the State
concerning final groundwater cleanup levels based on the scope and/or applicability of
several potential groundwater ARARs which have not yet been resolved. These potential
ARARs may impact the duration of cleanup activity at the four WABOU groundwater sites
and are discussed in more detail in Section 6.4.3.
6.3 Determination of ARARs
6.3.1 Methodology
The ARARs identified in this section have been used to establish the requirements for
WABOU sites and interim remedial alternatives. The ARARs in this section identify those
requirements that are applicable or relevant and appropriate to groundwater remediation,
those that had no relevancy were excluded. Specifically excluded were:
1. Location-specific requirements addressing conditions not present at WABOU
remediation sites.
2. Chemical-specific requirements for COCs not present at WABOU remediation sites.
3. Action-specific requirements for remedial alternatives not utilized at WABOU
remediation sites.
The list of ARARs for WABOU sites and groundwater remedial actions is provided in
Tables 6-1 through 6-5.
6.4 ARARs Evaluation and Discussion
6.4.1 Action-Specific ARARs
These ARARs place restrictions on remedial activities mat may negatively impact the
surrounding environment. The WABOU groundwater remedial alternatives were analyzed
to identify potential impacts to the environment. Considered were:
• Hazardous Waste Treatment, Storage and Disposal Requirements—These require-
ments are technology or activity-based requirements that place limitations on actions
taken with respect to the hazardous waste. Regulations promulgated under the
RDD-STO/98096Q015.DOC (ue209.DOC) . 61
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PART II DECISION SUMMARY
applicable provisions of the state authorized federal RCRA and more stringent provi-
sions of the California Hazardous Waste Control Law (HWCL) are relevant and appro-
priate to RCRA-pennitted storage facilities and proper characterization of hazardous
waste, and storage and disposal of such waste. If any hazardous wastes are identified
which will be transported offsite, they will be disposed of and handled under applicable
provisions of the state authorized federal RCRA program.
Many of the HWCL provisions are either applicable or relevant and appropriate because
they describe requirements for the safe handling of contaminated materials and
precautions for preventing further contamination. These requirements are identified in
Table 6-1.
• Air Resources Requirements—State legislation divides the state into local air pollution
control districts and allows each district to enforce the requirements of the California
Clean Air Act within its jurisdictional boundaries. Travis AFB is located in the Bay Area
Air Quality Management District (BAAQMD). The applicable air regulations incor-
porated into the WABOU Groundwater IROD as ARARs are identified in Table 6-2. In
addition, most of the rules in the State Implementation Plan (SIP), adopted pursuant to
the Federal Clean Air Act, are federal ARARs. Table 6-2 contains a brief description of
the substantive requirements and their applicability to the site, remedial action, or
technology used to clean up the site.
• Water Resources Requirements—Several California statutes and regulations that
protect the waters of the State have been identified and incorporated as ARARs. These
ARARs establish the remedial objectives and requirements for COCs present at
WABOU groundwater remediation sites.
The Porter-Cologne Water Quality Control Act (PCWQCA) 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 state through its
regional water quality control boards to protect the quality of surface water and
groundwater. Regulations promulgated pursuant to the PCWQCA are identified in
Table 6-3. A further discussion of water remediation requirements is included in the
chemical-specific ARARs section to follow.
• Groundwater Extraction Treatment and Discharge Requirements—The extraction of
groundwater at LF008, DP039, and SS041/SD043 will result in a reduction in the local
groundwater levels. However, these changes in groundwater levels have been
determined to not have a significant impact on the local vernal pools surrounding these
sites. The increase flow rates in Union Creek due to the surface discharge of treated
water was also considered and determined to not significantly impact Union Creek.
6.4.2 Location-Specific ARARs
These ARARs place restrictions on remedial activities that may be conducted onsite because
of the presence of unique site features. The location of the WABOU groundwater sites and
surrounding areas were analyzed for unique site features to identify ARARs. The unique
site features considered were:
RDO-SFCV9e0960015.DOC(UB209.DOC) 62
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PART II CESSION SUMURY
Habitats of Rare, Threatened, Endangered, and Special-Status Species—Vernal pools
which may contain an endangered species, including the Vernal Pool Tadpole Shrimp
and the Vernal Pool Fairy Shrimp, have been identified. Other endangered species,
including the Black-Shouldered Kite, Boggs Lake Dodder, Burrowing Owl, Coopers
Hawk, California Gull, Golden Eagle, Loggerhead Shrike, Northern Harrier, Red Fox,
Tri-colored Blackbird, Contra Costa Goldfields, Northwestern Pond Turtle, San
Francisco Forktail Damselfly have been observed at least once at Travis AFB and have
the potential to be found at WABOU sites.
Several federal ARARs were identified which impact site ecology. The Endangered
Species Act and implementing regulations set forth in Table 6-4 apply to those remedial
actions at WABOU sites where impacts to endangered wildlife could occur. The
operation of groundwater treatment facilities is not expected to impact any endangered
species; however, the construction of pipelines for groundwater extraction and other
intrusive remedial support activities could affect those resources that are present. To
ensure that regulatory requirements are followed and impacts are avoided or mitigated,
all sites will be surveyed in consultation with the U.S. Fish and Wildlife Service for the
presence of these resources prior to the commencement of remedial activities. This
consultation will begin after all necessary site-specific data concerning ihe construction
and operation of the groundwater treatment equipment become available.
Several more stringent state ARARs protective of site ecology have also been identified.
The California Fish and Game Code (CFGC) and regulations promulgated under this
Code, which protect rare, endangered, or threatened species or habitats, require
alternative actions at sites where impacts have the potential to occur. These
requirements are provided in Table 6-5. In addition to these state counterparts to the
Endangered Species Act, the CFGC also establishes several requirements to protect site
wildlife by prohibiting or restricting the unauthorized taking of other wildlife. The
CFGC also regulates to protect aquatic life living in the waters of the state. All remedial
activities that have the potential to cause a discharge to any stream lake or other body of
water must comply with the requirements of the CFGC. U.S. EPA does not acknowledge
that all CFGC requirements are more stringent than federal requirements but concurs
with the Air force decision to comply with both federal and state requirements as
ARARs in mis IROD. CFGC ARARs are found in Table 6-5.
Historically or Culturally Significant Properties—Some buildings on Travis AFB have
recently been identified as Cold War Era buildings and historically significant.
However, none of these buildings are affected by WABOU remedial activities.
Wilderness Areas, Wild and Scenic Rivers, and Coastal Zones—No wilderness areas,
wild and scenic rivers, or coastal zones exist within the boundaries of Travis AFB.
Therefore, requirements related to these areas are not applicable or relevant to WABOU
sites and actions.
Earthquake Faults—Although the Vaca-Winters and the Vaca-Kirby faults are located
in the Travis AFB area, WABOU sites are not located on these faults.
RDD-SFO/960960015.DOC (UB209.DOC)
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PART II DECISION SUMMARY
6.4.3 Chemical-Specific ARARs
Discharges of Effluent to Surface Water—Surface water at Travis AFB includes
Union Creek which is a minor tributary to the Suisun Marsh. However, design,
construction, and operation of remedial actions will have a negligible impact upon surface
water. One of the options at all sites for which groundwater treatment has been selected is
the discharge of treated groundwater to Union Creek. Provisions of 40 CFR Part 122
regulate discharge to surface waters. NPDES requirements establish standards for
discharges to surface waters of the United States, and are provided in Table 6-6. The
substantive CRWQCB requirements of federal or more stringent state ARARs for discharge
of treated effluent to surface waters are included in Table 6-7.
Discharges of Effluent to Groundwater—The reinjection of treated groundwater is not a
representative process option and has not been incorporated into any of the selected
remedial alternatives identified in the WABOU Groundwater IROD.
Discharge of Effluent to Land—Irrigation is the designated beneficial use of treated
groundwater at Travis AFB. The use of reclaimed and treated groundwater for irrigation
activities shall meet the substantive standards set forth by the regional water quality control
board order which establishes the general discharge requirements for treated groundwater.
These standards ensure that reclaimed water is segregated from potable water sources and
does not migrate or escape from the area of irrigation. Table 6-8 provides a list of the
effluent treatment levels for beneficial use.
Aquifer Remediation Objectives—The State Water Resources Control Board (SWRCB)
Resolution 92-49, Section IDLG is a requirement for the establishment of final aquifer
cleanup levels. However, the Air Force does not agree with the state on the full applicability
of all the substantive requirements of this resolution and its impacts on the remedial actions
and activities. Because final aquifer cleanup levels are not established in this IROD, this
requirement is not an ARAR. The purpose of using an IROD in lieu of a ROD is to prevent
the delay of remedial actions that would have resulted from this disagreement and to obtain
the data needed to resolve this disagreement.
SWRCB Resolution 68-16 has been identified by the State as an ARAR for the protection of
both surface water and groundwater of the state. All parties agree that this resolution is an
ARAR with respect to active discharges of treated effluent to surface waters. However, the
Air Force and U JS. EPA do not agree with the state on the full applicability of all the
substantive requirements of mis resolution and its impacts on the remedial action activities.
HDDSF0880960015.DOC{l»B209.DOC)
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Table 8-1
Travis AFB • WABOU Groundwater Site*
Federal ARARs*
Wasta Transfer, Treatmant, and Storage and Disposal Requirements
(California Statutes and Regulations Comprising Federal Authorized RCRA Program)
Requirement,
Standard, or
ITttte 22 OCR
66262.11
Applicable
Requires a facility to determine as to whether waste is
Remarks Sites and Alternatives
resulting from treatment processes.
41.43
Q5.G6 I
TOe22CCR
Chap 14 Art 6
66264.94
66264.96{c)
66264.97
Applicable
Applicable
Applicable
Establishes general groundwater monitoring
retirements and concentration limits.
Establishes monitoring requirements upon removal of
waste/contaminated material from a management unit.
Requires monitoring showing compliance with water
duality standards for 3 consecutive vears.
Establishes groundwater monitoring requirements
development of a comprehensive
monitoring program for the site
41.43
G5.G6
Title 22 CCR
Chap 14, Art 9
(Standards for
Owners and
Operators of
Hazardous
Waste Transfer,
Storage, and
Treatment,
Disposal
Facilities -
Management of
Containers)
66264.171
66264.172
66264.173
66264.174
66264.175
66264.176
66264.177
66264.178
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
ADoroDriate
Relevant and
Appropriate
Relevant and
Appropriate
Sets standards for containers holding hazardous
waste or chemicals recovered from sedknents,
surface soils, or groundwater.
Requires use of containers that are compatible with
the recovered material for the storage of that material.
Requires containers used to transport material to be
closed during transport and that waste be handled to
minimize damage to containers.
Establishes requirements for inspecting containers
weekly.
Establishes requirement for adequate secondary
containment of stored waste.
Requires isolating waste from sources of ignition if
waste is ignitabte.
Requires segregation of waste from incompatible
waste. .._
Establishes the requirement to remove all hazardous
waste and waste residue at closure.
appropriate to sites or actions where
waste containers are used.
Containers will be used to transfer and
store wastes generated from
construction activities or the operation
of remedial actions. Examples would
include spent carbon from treatment
plants, drill cuttings from well
installation, free product removed from
a plume, etc.
Sect 66264.178 is relevant and
appropriate whan sites are closed and
wastes or residue, as described above,
are on-site at closure.
41,43
G5.G6
RDD-SFO980980009.DOC (LNB216.DOC-1)
-------
Table 6-1
Travis AFB - WABOU Groundwatw Sites
Federal ARARs*
Waste Transfer, Treatment, and Stores* «nd Disposal Requirements
(continued)
Requirement,
Title 22 OCR
Chap 14, Art 10
(Standards for
Owners and
Operators of
Hazardous
Waste Transfer,
Treatment,
Storage, and
Disposal
Facilities -Use
and Management
of Tank Systems)
Trtle22CCR
Chap 14, Art 15
(Standards for
Incinerators)
66264.192
66264.193
66264.194
66264.195
66264.196
68264.197
66264.198
66264.199
66264.341
66264.342
66264.343
66264.344
(a)
66264.345
66264.347
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Establishes design/installation requirements lor new
tank systems/components.
Tank system requirements including containment and
detection of releases.
Delineates tank system requirements Including
operating requirements.
Delineates requirements tank systems Including
inspections.
Delineates tank system requirements Including
response to leaks or spills.
Delineates tank system requirements Including closure
and post-closure care.
Delineates requirements for tank systems Including
special care reauirements for reactive wastes.
Delineates special tank system requirements for
incomoatiblfl wastes.
Requires owner or operator of thermal treatment units
to conduct sufficient waste analysis to verify that waste
feed to the incinerator is wilhin physical and chemical
composition limits
Establishes treatment requirements for Principal
Organic Hazardous Constituents (POHCs) in the waste
feed.
Establishes construction, maintenance and
performance standards for incinerators that bum •
hazardous waste.
Establishes operating conditions under which
hazardous wastes may be burned.
Establishes operating requirements under which
hazardous wastes may be burned.
Establishes Inspection and monitoring requirements for
Sections in this article are relevant ana
appropriate to alternatives Incorporating
the use of tanks or tank systems as part of
the remedial equipment. Tanks win be used
at treatment plants to store contaminated
water prior to treatment tanks win also
be used for temporary storage of free
product, if necessary. Section 66264.197(a),
(c)(3), and (c)(4) (cost estimates and
financial responsibility requirements) are not
ARARs. Section 66264.198 is relevant and
appropriate to sites with kjnitabte waste
P.O., free product] or reactive waste.
Remedies utilizing reactive oxktfzers, such
as ultraviolet oxidation or catalytic oxidation,
trigger this requirement
pjgjlJIIfcBi^il^BBMBBBBBBBSliMSlll^^MlSBiSl^Bl^^^^^^^^^^^^^^^^^^^™
Applicable to remedial actions that utilize
thermal treatment units. Only the
substantive requirements set form in these
sections are ARARs. Permitting
requirements set forth in these sections are
procedural and not ARARs
38«ndAI
08, 39,
41,43
08,39.
41,43
ernaUvas
G3.G4.
G5.G6
64,65,
66
RDr>SFQ/9e0960009.DOC (UB21B.DOC-2)
-------
Table 6-1
Travis AFB - WABOU Groundwater Sites
Federal ARAHs*
Waste Transfer, Treatment, and Storage and Disposal Requirements
f A^_^Al_. .— -iv
Requirement,
Standard, or
Source Criterion Type Description Remarks c - .,
Title 22 OCR
Chap 14, Art 16
66264.601
66264.602
66264.603
Applicable
Applicable
Applicable
Specifies performance standards for
miscellaneous units that transfer, treat, store
or dispose of hazardous waste.
Establishes analysis, inspection, response,
reporting, monitoring and corrective action
standards for miscellaneous units.
Establishes maintenance standards for
miscellaneous units.
Applicable at Travis AFB sites where air strippers or
dual-phase extraction are used as part of the
remedial action.
Section 66264.602 requirements related to
response and reporting procedures are not ARARs.
08, 39,
41,43
G4. G5.
G6
Title 22 CCR
Chap 14,
Art 27 (Air
Emission
Standards for
Process Vents)
66264.1032
66264.1033
66264.1034
66264.1035
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Establishes emission limits when process
vents are used.
Establishes standards for closed vent
systems and control devices.
Establishes test methods and procedures for
closed vent systems.
Establishes record keeping requirements;
performance & design analysis/ parameters
for closed vent systems;
Relevant and appropriate to alternatives where
closed vent systems are used. This
includes sites with remediation systems that have
system vents, to include air strippers,
UV oxidation, carbon treatment vessels and
catalytic oxidation equipment.
08.39T
41.43
G3, G4,
G5, G6
Title 22 CCR
Chap 14, Art 28
(Air Emission
Standards for
Equipment
Leaks)
66264.1054
66264.1063
66264.1064
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Establishes that pressure relief devices in
gas/vapor service shall be operated with no
detectable emissions.
Establishes leak detection monitoring
requirements.
Establishes record keeping requirements for
gas/vapors extraction systems.
Relevant and appropriate for actions where
gas/vapor extraction systems are used.
39
G5, G6
Title 22 CCR
Chap 18, Art 1
(Land Disposal
Restrictions -
General)
66268.3
66268.7
66268.9
Applicable
Applicable
Applicable
Establishes land disposal restrictions,
including a prohibition of using dilution as a
substitute for treatment.
Establishes land disposal restrictions,
including requirements for waste analysis
and record keeping.
Establishes land disposal restrictions
including special rules for wastes that exhibit
a characteristic.
Applies to hazardous waste generation from site
excavation or from site construction activities.
Restricts on-site disposal activities in unauthorized
areas.
Section 66268.7. para (a)(1), (b)(1), (2) and (3). and
(c)(2) are substantive requirements. The remainder
of the section is procedural and not ARARs.
08, 39,
41,43,
G3, G4,
G5.G6
RDD-SFO/980980009.DOC (LNB216.00C-3)
-------
Tob!e6-1
Travis AFB - WABOU Groundwater Sites
Federal ARARs*
Waste Transfer, Treatment, and Storage and Disposal Raqulrements
(continued)
Requirement,
Standard, or
Source Criterion Type Description Remarks Sites and Alternatives
Title 22 OCR
Chap 18, Art 2
All Sections
s
Applicable
Establishes treatment technology (or disposal of waste
to land for RCRA and non-RCRA wastes identified in
section 66268.106.
Applicable to sites where material, state
regulated waste, or secondary hazardous waste
is generated during construction activities (to
include excavation for well installation, pipeline
installation, and foundations for treatment
facilities). Wastes identified will be managed in
accordance with these standards.
08. 39.
41,43.
G3, G4,
G5.G6
Title 22 OCR,
Chap 18 Art 3
Titte 22 CCR,
Chap 18 Art 3
66268.30
66268.31
66268.32
66268.33
66268.34
66268.35
66268.36
66268.37
66268.38
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Establishes waste-specific LDRs
Establishes LDRs for wastes containinq dioxin.
Establishes LDRs for certain hazardous wastes.
Establishes LDRs • First Third Wastes.
Establishes LDRs - Second Third Wastes.
Establishes LDRs - Third Third Wastes.
Prohibits land disposal of newly listed wastes.
Prohibits land disposal of corrosive and characteristic
wastes with vacated treatment standards.
Identifies waste specific prohibitions on newly
identified organic toxicity characteristic wastes &
newly listed coke by-product and chlorotoluene waste.
Applicable to groundwater sites where media
excavated for equipment installation is classified
as hazardous waste and disposed/ treated
on-site. Applicable to wastes excavated or
removed from soil sites. Requires identification
of waste through the proper characterization
process.
08, 39,
41,43
G2, G3,
G4. G5,
G6
Title 22 CCR
Chap 18 Art 4
Title 22 CCR
Chap 18 Art 5
Title 22 CCR
Chap 18 Art 10
Title 22 CCR
Chap 18 Art 11
All Sections
AH Sections
66268.100
All Sections
Applicable
Applicable
Applicable
Applicable
Identifies treatment standards for halogenated
orqanic compounds regulated bv section 66268.32
Establishes prohibitions on storage of hazardous
wastes restricted under Article 3 of this chapter or
RCRA Section 3004 (42 USC 6924).
Establishes land disposal prohibitions for non-RCRA
hazardous wastes.
Establishes disposal restrictions, treatment standards,
& prohibitions, for certain identified hazardous wastes.
Applicable to sites where excavated material is
classified as hazardous waste. Identified waste
will be managed in accordance with these
standards, if disposed of on land and not in a
CAMU or AOC. Applicable at sites where
wastes or contaminated soils are excavated or
removed.
08, 39.
41,43
G2, G3,
G4.G5,
G6
Title 22 CCR
Chapter 43
(Extremely
Hazardous
Wastes)
67430.3
Applicable
Establishes requirements for the removal of spilled or
improperly deposited extremely hazardous wastes.
Applicable to sites where unintentional spills
may occur.
08, 39,
41,43
G2, G3,
64, G5,
G6
RDO-SFO/980980009.DOC (LNB216.DOC-4)
-------
Source
Requirement,
Standard, or
Criterion Type
Description
Table 6-2
Travis AFB • WABOU Groundwater Sites
State ARAHs
Air Remediation Requirements
Remarks
Sites and Alternatives
Regulation
2, Rulel
(Bay Area
Air Quality
Management
District
Regulations)
308
316
501
Applicable
Applicable
Applicable
Establishes that fugitive emissions
from equipment or facilities must
comply with all applicable
requirements.
Establishes maximum levels for toxic
air contaminants, which, if exceeded,
require a risk screening analysis.
Establishes that continuous emission
monitors meet certain requirements.
Applicable to actions where air strippers or other systems
using pressurized components (UV oxidation, carbon
adsorption, catalytic oxidation and ion exchange) may
result in (uqitive VOC emissions.
Applicable to actions that have the potential to emit toxic
air contaminants (e.g. TCE). Applicable to air stripping, UV
oxidation, carbon adsorption, catalytic oxidation and ion
exchange.
Applicable to all sites or actions where air stripping, UV
oxidation, carbon adsorption, catalytic oxidation and ion
exchange technologies are used in the remedial action.
08,39,41,
43
G3. G4,
G5.G6
Regulation
2, Rule 2
112
301
Applicable
Applicable
Establishes exemptions for
secondary pollutant emissions from
abatement control equipment that
complies with BACT or BARCT
requirements.
Establishes BACT requirement for
new sources emitted in excess of 1 0
Ibs/day of non-precursor organic
compounds, precursor organic,
compounds, NOx, SOx, PM-10, COj.
Applicable to actions where BARCT or BACT abatement
devices are used (i.e. carbon adsorption is used together
with catalytic oxidation or UV. oxidation or ion exchange)
but where secondary emissions from the abatement
equipment still exist.
Applicable to actions with potential to discharge to air. Not
applicable for permitting requirements or authority to
construct. Applicable for determining the applicability of
BACT to a new source. Remedial alternatives using air
strippers must ensure BACT is used (i.e. catalytic oxidation
with carbon adsorption) to control emissions in excess of
levels specified in the rule.
08,39
G4. G5,
G6
Regulation 6
301
302
303
501
Applicable
Applicable
Applicable
Applicable
Establishes limitations on visible
emissions and opacity.
Establishes limitations on opacity.
Establishes limitations on emission
rates, concentration, visible
emissions and opacity.
Establishes requirements for
sampling facilities and instruments.
Applicable to sites where excavation or construction
activities have the potential to release paniculate matter
into the air (i.e. dirt and dust), or at sites where portable
soldering, brazing, welding equipment is used. Also
applicable at sites where portable combustion engines of
< 25 liters ot displacement are used. Applicable to all
actions subject to Regulation 6.
08, 39, 41,
43
G3, G4,
G5,G6
ROD-SFOra80980009.DOC (LNB216.DOC-5)
-------
Source
Requirement
Standard, or
Criterion Type
Table 6-3
Travis AFB - WABOU Groundwater Sites
State ARARt
Water Board Requirements
Description
Remarks
Sites and Alternatives
Federal Water
Pollution Control
Act Section 402,
Porter Cologne
Water Act;
California Water
Code, Division 7,
Sections 13000,
13140, 13240,
Water Quality
Control Plan ior
the San
Francisco Bay
Basin
SWB
Resolution
68-16
Applicable
Establishes policy that whenever the existing
quality of water is better than the quality
established in policies as of the date on which
such policies become effective, such existing high
quality will be maintained until it has been
demonstrated that any change will be consistent
with maximum benefit to the people of the State,
won't unreasonably affect present and anticipated
beneficial use of such water and will not result in
water quality less than prescribed in the policies.
Discharges or proposed discharges to existing
high quality waters will be required to meet waste
discharge requirements which will result in the best
practicable treatment or control of the discharge
necessary to assure that a pollution or nuisance
will not occur and the highest water quality
consistent with maximum benefit to the people of
the State will be maintained.
,
Applicable to sites where groundwater actions
will cause active discharges to surface water
(i.e., Union Creek). The Air Force and the U.S.
EPA agree to disagree with the RWQCB as to
the applicability of this section with respect to
passive discharge and plume migration.
San Francisco Bay Region Order Number 94-
087 establishes requirements for discharge or
reuse of extracted and treated groundwater that
was contaminated by VOCs.
Contaminants in treated groundwater shall not
exceed the more stringent of the substantive
standards set forth in Order 94-007, MCLs, or
such levels necessary to preclude degradation
of the receiving water quality. The numeric
effluent limitations for discharges of treated
water that comply with Resolution 68-1 6 are
specified in Table 6-6. The discharge must also
comply with paragraphs A.1, A.2, and A.3
(prohibitions) of General Waste Discharge Order
94-087.
08,
39.
41,43
G3, G4,
G5.Q6
Porter Cologne
Water Act;
CWC Sections
13000, 13140,
13240,
SWB
Resolution
88-63
Applicable
Designates all ground and surface water of the
state as potential drinking water with certain
exceptions (TDS>3,000 ppm and it is not
reasonably expected by Regional Boards to supply
a public water system, well yield<200 gpd,
geothermic resources, waste water conveyance
facility, or can't be reasonably treated for domestic
use).
Applicable to actions that will result In the
discharge of treated groundwater to surface
waters (i.e. Union Creek). The existing beneficial
uses of Union Creek include navigation, contact
and non-contact recreation, fish spawning, warm
freshwater habitat, and wildlife habitat.
08, 39,
41,43
G3. G4,
G5.G6
RDD-SFO/980980009.DOC (LN8216.DOC-8)
-------
Source
Requirement
Standard, or
Criterion
Table 6-3
Travis AFB - WABOU Groundwater Sites
State ARARs
Water Board Requirement
(continued)
Type
Description
Remarks
Sites and Alternatives
Title 27 CCR
(CWC Section
13140-13147,
13260,13263,
13267, 13304)
20090 (d)
Relevant and
Appropriate
Establishes exemption from provisions of
this subchapter for actions taken by or at
the direction of public agencies to clean up
or abate conditions of pollution or
nuisances resulting from unintentional or
unauthorized releases of waste or
pollutants to the environment. Requires
that wastes, pollutants, or contaminated
materials removed from the immediate
place of release are discharged according
to Art 2. Remedial actions intended to
contain such wastes at the place of release
shall implement applicable provisions of
this subchapter to the extent feasible.
Relevant and appropriate to monitoring
requirements and other specific actions that are
not related to final cleanup levels or goals at sites
where active remediation will occur. The Air
Force does not concur with the RWQCB's
interpretation that this requirement is applicable to
unauthorized or unintentional releases.
08, 39,
41,43
03, G4.
05, G6
U.S. Office of
Solid Waste
RCRA Groundwater
Monitoring, Draft Tech.
Guidance, Nov. 1992
(EPA/530-R-93-001)
Performance
Standard
Sets forth requirements for the
development of a groundwater monitoring
program.
Applies to the development of a comprehensive
monitoring program for the site (also reference
Table 6-1 , 22 CCR Section 66264.94, 66264.96,
and 66264.97).
08, 39,
41,43
G3, G4,
G5.G6
Regional
Water Quality
Control Board
S.F. Bay Basin Water
Quality Control Plan,
Chapter 2, Beneficial
Uses.
S.F. Bay Basin Water
Quality Control Plan,
Chapter 3, Water
Quality Objectives.
Applicable
Applicable
Establishes beneficial uses of surface
waters.
Establishes discharge to surface
requirements, including receiving water
quality objectives and receiving water
limits.
Applicable to define beneficial uses of surface
waters to which treated effluent is discharged.
Beneficial uses of Union Creek and downstream
receiving waters include navigation, contact and
non-contact recreation, fish spawning, warm
freshwater habitat, and wildlife habitat.
Applicable where effluent is discharged to the
surface. Surface waters shall not contain
concentrations of chemical constituents in
amounts that affect any beneficial use or the
objectives for selected toxic pollutants identified in
Tables 3-3 and 3-4.
08, 39,
41,43
G3, G4,
G5.G6
RDD-SFO/980980009.DOC (LN8216.DOC-9)
-------
Requirements
Table 6-4
Travis AFB - WABOU Groundwater Sites
Federal ARARs
Requirements under the US Code and Related Regulations
sn«M criiorion' Tvne Description Remarks Sites and Alter
Title 16 USC
(Endangered
Species Act)
1531(c)
1S3MO
Applicable
Requires action to conserve endangered species and
critical habitats upon which endangered species
depend. Includes consultation with the Dept of Interior.
performed in such a manner as to identify
the presence of and protect endangered or
threatened plants and animals at the site.
Species at Travis AFB include the Black-
Shouldered Kite, Boggs Lake Dodder,
Burrowing Owl, Coopers Hawk, California
Gull, Golden Eagle, Loggerhead Shrike,
Northern Harrier, Red Fox, Tri-colored
Blackbird, Vernal Pool Fairy Shrimp,
Contra Costa Goldfields, Northwestern
Pond Turtle, San Francisco Forktail
Damselfly, Vernal Pool Tadpole Shrimp.
41,43.
natives
G4.G5,
G6
Title 16 USC
(Fish and Wildlife
Coordination Act)
662
Applicable
Regulates site actions affecting fish or wildlife in lakes.
stream, or other water bodies by requiring coordination
between lead agency and the US Fish and Wildlife
Service, Dept. of the Interior, and applicable state
and effluent discharges at sites that are
located at or near, or which may impact.,
Union Creek and pond.
41,43
G5.G6
Title 16 USC
(Migratory Bird
Treaty Act)
703
Applicable
Prohibits unlawful taking, possession, and sale of almost
all species of native birds in the U.S.
Shouldered Kite. Burrowing Owl, Coopers
Hawk, California Gull, Golden Eagle.
Loggerhead Shrike. Northern Harrier, Tri-
colored Blackbird.
41.43
G4, G5,
G6
Federal Clean
Water Act, Sect.
404, Title 33 CFR
Part 330,Appx A,
Subpart B -
Army Corps of
Engineers
Nationwide
Permit Program
Paragraph 12
Paragraph 13
Paragraph 27
Applicable
Applicable
Applicable
Establishes Nationwide Permit for discharges of material
for backfill or bedding of utility lines, including outfall and
intake structures affecting the waters of the U.S.
Establishes Nationwide Permit for bank stabilization
activities required for erosion prevention.
Establishes requirements for activities in waters of the
United States associated with restoration of altered and
degraded non-tidal wetlands and creation of wetlands on
paragraphs are applicable. The notification
requirements are not ARARs. Site activities
related to construction and installation of
remedial equipment give rise to these
requirements.
41,43
G5, G6
RDD-SFO/9809B0009.DOC (INB216.DOC-10)
-------
Table 6-4
Travis AFB • WABOU Groundwater Sites
Federal AHARs
Requirements under the US Code and Related Regulations
(continued)
Requirement
Standard, or
Clean Water Act,
Section
404, Title 33 CFR
Part 330, Appx A,
SubC
Army Corps of
Engineers
Nationwide
Permit
Conditions
(NWP)
Paragraph 2
Paragraph 4
Paragraph 5
Paragraph 1 1
Applicable
Applicable
Applicable
Applicable
Requires structures or fill authorized be maintained,
including maintenance to ensure public safety.
Requires that no activity may substantially disrupt
the movement of those species of aquatic life
indigenous to the water body.
Requires heavy equipment working in wetlands
must be placed on mats or other measures be taken
to minimize soil disturbance
No activity is authorized under any NWP if likely to
jeopardize the continued existence of a threatened
or endangered species, or species proposed for
such designation, as identified under the
Endangered Species Act, or if likely to destroy or
adversely modify the critical habitat of such species.
The substantive portions of these
paragraphs are applicable. The
notification requirements are not ARARs.
41,43
G5.G6
Title 40 CFR
Part 122 -EPA
Administered
Permit Programs:
The National
Pollutant
Discharge
Elimination
System (NPDES)
122.26
122.41(d)
1 22.41 (e)
122.41(j)
(1)(3»(4)
122.41(l)(6)
122.41 (m)
1 22.41 (n)
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Requirements to ensure storm water discharges
from remedial activities do not contribute to a
violation of surface water quality standards.
Requires all reasonable steps be taken to minimize
or prevent discharges that have a reasonable
likelihood of causing adverse impacts on surface
water quality.
Requires proper operation and maintenance of
treatment and control systems/ equipment.
Establishes requirements for monitoring and
recordation of monitoring results.
Establishes informational requirements for any
noncompliance which may endanger health or the
environment
Establishes prohibitions, limitations and restriction
on treatment plant bypass.
Defines and establishes parameter for upset
conditions in a treatment plant.
Applicable at all sites where there will be
discharge to the stormwatar system and
discharges to Union Creek. These
sections relate to effluent limitations and
monitoring requirements to be applied
during the development of a monitoring
plan. The SRWQCB is authorized to
implement the NPDES program in the
State of California. California Regional
Water Quality Control Board, San
Francisco Bay Region Order 94-087
establishes substantive discharge
standards. Only substantive portions of
Part 122 are ARARs; reporting
requirements are procedural.
43
G5, G6
HDD-SFO/9809B0009.DOC (LNB216.00C-11)
-------
Table 6-4
Travis AFB - WABOU Groundwater Sites
Federal ARARs
Requirements under the US Code and Related Regulations
(continued)
Requirement
Standard, or ,
^uurce p.u-w«» Tifru. n«Ecrlntion . —
Title 40 CFR Part
122 (Continued)
^•^™»^— — ^~
Title 40 CFR
Part 141
40 USC Sec. 300
(National Primary
Drinking Water
Standards)
122.44(d)
122.44(g)
122.44(i)
122.45(C)
122.45(d)
12245(e
122.45(f)
122.45(g)
122.48(a)
122.48(b)
™«™«— ^«
141.11
141.12
141.61
141.62
• m*-~
Applicable
Applicable
Applicable •
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
.__••»—•—«
Relevant and
Appropriate
Relevant and
Appropriate ,_
Relevant and
Appropriate
Relevant and
Appropriate
Requires that discharges to surface water must achieve federal
and state water quality standards.
Establishes monitoring requirements lo assure compliance with
permit limitations and requirements to monitor.
Establishes techniques and methodologies for monitoring effluent
levels of metals.
"Establishes format for reporting effluent limitation standards ana
prohibitions.
Establishes format and limit criteria for non-continuous discharge.
Establishes requirements and exceptions for pollutants
expressed in terms of mass. — ,
trJt^kitnknn »rn>4iic inr nniiiitanta in thn discharaer's Intake water.
Establishes requirements for proper use, maintenance, and
installation of monitorinq equipment or methods.
Establishes requirements for monitoring including type, intervals,
and frequency sufficient to yield data which are representative of
the monitored activity including, when appropriate, continuous
monitorinq.
Establishes the federal allowable maximum contaminant levels
(MCLs) for arsenic in community water systems and nitrates in
non-community water systems. .... .
Establishes federal maximum contaminant levels (MCLs) for
trihalomethanes. .
Establishes MCLs for organic contaminants. Requires the best
technology, treatment technique, or other means available for
achieving compliance of MCLs contaminants.
Establishes MCLs for inorganic contaminants. Requires the best
technology, treatment technique, or other means available for
achieving compliance of MCLs for identified contaminants, except
ternaries S
(Continued)
Relevant and appropriate to sites
where discharge of treated
groundwater to potential sources
of drinking water will occur.
Establishes effluent treatment
standards for certain
constituents which are not
addressed by the substantive
requirements of California
Regional Water Quality Control
Board, SF Bay Region, Order
Number 94-087.
tes and A
08, 39,
41.43
08, 39,
41,43
llernatlves
lad, U
-------
Table 6-4
Travis AFB - WABOU Groundwater Sites
Federal ARARs
Requirements under the US Code and Related Regulations
(continued)
Requirement
Source SEE?'" 1*- Demotion RemarK, Sites and A,
40 CFR Part 230
(Clean Water Act -
Disposal of
Dredged or Fill
Material)
230.10
230.71
230.72
230.73
230.74
230.75
230.76
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Prohibits discharge of dredged or fill material into
waters or wetlands without a permit. Establishes
limitations on such discharges.
Places limitations/requirements on the disposal and
treatment of the dredged or fill material discharged.
Establishes requirements and methods for the
control of the effects of dredged or fill material after
discharge, through use of levees, caps, lined
containment areas, timing and placement.
Establishes requirements for minimizing discharge
effects by use of specific disbursement methods.
Requires use of available technology, adapted to
the particular site, to minimize the adverse effects
of dredge and fill discharges.
Requires minimization of adverse effects on
populations of plants and animals caused by the
discharge of dredge or fill materials.
Requires use of fill or dredge material discharge
methods that minimize the adverse effects on
Applicable to sites where wetlands
and vernal pools are located.
Permitting requirements are
procedural and are not ARARs.
08. 39, 43
lernatives
G3, G4,
G5.G6
RDD-SFO/980980009.DOC (LNB21B.OOC-13)
-------
Table 6-5
Travis AFB - WABOU Groundwater Sites
Slate ARARs
Fish and Game Requirements
Requirement,
So,,rr.» San '"TV™ DescriDtlon Remarks SI es and AH rnatlvea §
California
Fish and
Game
Code
1908
2080
2090
2091
2092
3005
3511
3513
4700
5050
5515
5650
Applicable
Applicable
Relevant
and
Appropriate
Relevant
and
Appropriate
Relevant
and
Appropriate
Applicable •
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Prohibits the possession, import, or taking or of rare
or endangered native plants.
Prohibits the import, taking or sale of threatened or
endangered native plants
Requires state lead agencies to consult with DF&G
to ensure authorized actions will not jeopardized
endangered or threatened species.
Requires state agencies to use alternative actions
where impact to threatened or endangered species
or habitat is found.
Requires state agencies to adopt reasonable
alternative actions where project would result in the
extinction of a species.
Prohibits taking of birds or animals with net, pound,
cage, trap, set line, wire, or poison.
Prohibits taking of birds identified as fully protected.".
Prohibits taking of protected migratory non-game
birds.
Prohibits taking or possession of mammals identified
as "fully protected."
Prohibits taking or possession of reptiles/ amphibians
identified as "fully protected."
Prohibits taking or possession of fish identified as
"fully protected."
Prohibits deposit or placement of specified materials
and substances into places where is can pass into
the waters of the state.
endangered native plants exist. Requires site
surveys prior to action to determine presence of
endangered/threatened plants at the site and
consideration of potential impact.
Relevant and appropriate for federal agencies at all sites
where endangered or threatened species are located.
Requires coordination and, if appropriate, consideration
of alternative actions at sites where impact to
endangered or threatened species may occur. Will be
considered at all sites where active remediation occurs.
Applicable at all remediation sites where birds, animals,
or other wildlife identified by the applicable statutory
provision exist. Applicable to the extent that these laws
are more stringent than the Federal Endangered
Species Act or Migratory Bird Treat Act.
Applicable to all remediation actions or sites where
substances have a pathway to state waters.
41,43
G2. G3,
G4, G5,
G6
RDD-SFO/980980009.DOC (LNB216.DOC-6)
-------
Requirement,
Standard, or
Source Criterion TV
Title 14 OCR
40.00
40.10
460
640
670.2
670.5
Applicable
Table 6-5
Travis AFB • WABOU Groundwater Sites
State ARARs
Fish and Game Requirement
(continued)
Applicable
Description
Prohibits the taking or possession of native
reptiles and amphibians.
Applicable
Applicable
Applicable
Applicable
Prohibits the possession or taking of native
reptiles and amphibians. .
Prohibits the taking of certain fur bearing
mammals at any time.
Establishes requirement for fish and wildlife
planning to optimize fish and wildlife resources.
Establishes species, subspecies, and varieties
of native California plants as endangered,
threatened, or rare.
Establishes species, subspecies, and varieties
of native California plants as endangered,
threatened, or rare.
Remarks
Applicable to all site and action alternatives where identified
mammals, fish, reptiles or amphibians or plants exist. Will be.
considered at all sites where active remediation occurs
Requires site surveys prior to action to determine presence of
endangered/threatened plants at the site. Section 640 will be
considered to the extent feasible and consistent with CERCLA
planning documents. Species found at Travis AFB which are
covered by these sections include the Black-Shouldered Kite,
Boggs Lake Dodder, Burrowing Owl, Coopers Hawk, California
Gull Golden Eagle, Loggerhead Shrike, Northern Harrier, Red
Fox, Tri-colored Blackbird, Vernal Pool Fairy Shrimp, Contra
Costa Goldfields, Northwestern Pond Turtle, San Francisco
Forktail Damselfly, Vernal Pool Tadpole Shrimp.
Sites and Alternatives
08, 39,
41.43
G2, G3,
G4, G5,
G6
RDD-SFO/9809B0009.DOC (INB216.DOC-7)
-------
TABU 6-6
NKUcb tlTHieni umnauons lor I iea«su vaioui lunaioi .
Instantaneous Maximum
Constituent
Halogenated Volatile Organics*
Bromodichloromethane
Carbon Tetrachloride
Chlorobenzene
Chloroform
Chloromethane
Dibromochloromethane
1,4-Dichlorobenzene
1,2-Dichloroethane
1,1-Dichloroethytene
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
1,2-Dich!oropropane
Ethylene Dibromide
Tetrachloroethylene (PCE)
Trichloroethylene (TCE)
Vinyl Chloride
Total Halogenated Volatile Organics
Non-Halogenated Volatile Organles
Benzene
Ethylbenzene
Toluene
Xylenes
TPH - Gasoline
Semi-Volatile Organlcs*-'
Aldrin
Alpha-BHC
Beta-BHC
Gamma-BHC (Lindane)
Chlordane
4,4'DDT
4,4'DDD
Dieldrin
2,3,7,8-TCDD (Dioxins)
(ug/U
100.0b
0.5b
70.0"
100.0"
100.0b
5.05
0.5b
e.o5
e.o"
10.0"
5.0b
0.05b
5.0"
5.0"
0.5b
1.0b
29.0C
42.0C
17.0°
50.0d
1.4x10-*
0.013
0.046
0.063
5.9 xlO"4
6.0X10-4
8.4 x 10"4
1.4x10-*
1.4 x10'8
30-Day Median
{ug/u
,
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1.0
0.5
0.5
0.5
0.5
50.0d
1.4X10-4
0.013
0.046
0.063
5.9 X 10-*
6.0X10-4
8.4X10-4
1.4x10-*
1.4X10-8
RDD-SFO/980980002.DOC (iNB214.DOC)
84
-------
TABLE 6-6
Constituent
Endosulfan
Heptachlor epoxide
PCBs (Arochlors)
Total Polynuclear Aromatics (PAHs)
TPH - Diesel
Inorganics^*
Arsenic*
Cadmium
Chromium Vii
Total Chromium
Copper
Lead
Mercury*
Nickel
Selenium
Silver
Zinc _'
8 30-day Median Limits for Volatile Organics
b California Primary MCL
c Taste & odor threshold in water - USEPA
d Practical Quantitation Limit
8 Both instantaneous maximum and monthly
Instantaneous Maximum
(u.g/L)
2.0
1.1 X10"4
4.5 x 10'5
0.031
100.0C
10.0
1.1
11.0
11.0
12.0
3.2
0.012
160.0
5.0
4.1
110.0
are based on Best Available Technology.
median limitations are based on USEPA
30-Day Median
(ug/L)
2.0
1.1x10-*
4.5 x 10'5
0.031
50.0*
10.0
1.1
11.0
11.0
12.0
3.2
0.012
160.0
5.0
4.1
110.0
Freshwater Ambient Water
Quality Criteria.
For certain semi-volatile parameters, the PQL exceeds the effluent limitation. In these cases, the discharger
may use the PQL, as identified in the 1996 RD/RA Analytical Quality Assurance Project Plan (QAPP) to comply
with its effluent limits. As laboratory technology improves, and as QAPPs are updated, it may be necessary to
comply with more stringent PQLs in the future.
With the exception of arsenic, both instantaneous maximum and monthly median limitations are based on
USEQP Freshwater National Ambient Water Quality Criteria for Protection of Aquatic life, expressed as total
recoverable metal.
Limits for Cadmium, Copper, Lead. Nickel, Silver, and Zinc are based on an annual hardness of 100 mg/L of
CaCO3.
Arsenic limits are based on Best Available Technology.
Compliance with the Chromium VI limitation may be met as Total Chromium.
Compliance is achieved by meeting the Reporting Limit using EPA Method 7470/7471. The effluent shall not
contain more than 1 gram/day of mercury.
RDD-SFO/980980002.DOC (INB214.DOC)
85
-------
TABLE 6-7
Discharge Limitations __ . _ __ - _ -- — - : - — -
1. The discharge of waste shall not cause the following conditions to exist in the waters of the State at any place:
a) floating, suspended, or deposited macroscopic particulate matter or foam;
b) bottom deposits or aquatic growths;
c) alteration of temperature, turbidity, or apparent color beyond present natural background levels;
d) visible, floating, suspended, or deposited oil or other products of petroleum origin;
B) toxic or deleterious substances to be present in concentrations or quantities which will cause deleterious
> ySS^SS^S^MB. or waterfowl, or which render any of these unfit for human consumpfon
either at levels created in the receiving waters or as a result of biolog,cal concentrate.
2. The discharge of waste shall not cause excursions of the following limits in waters of the State in any place
within one foot of the water surface:
a) Dissolved oxygen;
For all tidal waters, upstream of Carquinez Bridge. 7.0 mg/L minimum; downstream of Carquinez Bridge,
5.0 mg/L minimum.
For nontidal waters, waters designated as cold water habitat, 7.0 mg/L minimum; waters designated as
warm water habitat, 5.0 mg/L minimum.
The median dissolved oxygen concentration for any three consecutive months shall not be less than 80% of
the dissolved oxygen content at saturation.
b) pH: The PH shall not be depressed below 6.5 nor raised above 8.5. nor be caused to vary from normal
ambient pH levels by more than 0.5 units.
3. The discharge shall not cause a violation of any applicable water quality standard II or receiving £^
by the Board or the State Water Resources Control Board as required by the Federal Clean Water Act and
regulations adopted thereunder. - --- •
Note- This table establishes narrative and numeric discharge limitation standards for treated S"^1"^
discharge^ to waters of the State. These discharge standards are derived from Calrfom,a Reg,onal Water Qua*
Control Board. San Francisco Bay Region, Order No. 94-087
RDD-SFO/980980002.DOC (LN8214.DOC)
-------
TABLE 6-8
Effluent Treatment Levels for Beneficial Reuse
Discharges to Land for Irrigation Purposes
Water reclaimed for beneficial use shall meet the following limits:
Constituent Instantaneous Maximum Limit (ug/L)
Volatile Organic Compounds
Vinyl Chloride °-5
0.5
Benzene
Dichloroethane °-5
All Others, Per Constituent 5-°
Semi-Volatile Organic Compounds
Per Constituent §L2——
The following limitations shall apply:
1. Water reclamation activities shall be limited to irrigation.
2. No reclaimed water shall be allowed to escape from the authorized use area by airborne, nor by surface
flow except in minor amounts associated with good irrigation practice, nor from conveyance facilities.
3. Reclamation involving irrigation shall not occur when the ground is saturated.
4. The use of reclaimed water shall not impair the quality of waters of the State, nor shall it create a nuisance
as defined by Section 13050{m) of the California Water Code.
5. Adequate measures shall be taken to minimize public contact with reclaimed water and to prevent the
breeding of flies, mosquitoes, and other vectors of public health significance during the process of reuse.
6. Appropriate public warnings must be posted to advise the public that the water is not suitable for drinking.
Signs must be posted in the area, and all reclaimed water valves and outlets labeled, as appropriate.
7. There shall be no cross-connection between the potable water supply and piping containing treated
groundwater intended for reuse.
Note: This table establishes narrative and numeric discharge limitation standards for treated groundwater
discharged to land. These discharge standards are derived from California Regional Water Quality Control
Board, San Francisco Bay Region, Order No. 94-087
RDD-SFO/9B0980002.DOC(LWB214.DOC) 87
-------
PART II DECISION SUMMARY
7.0 Works Cited
Association of Bay Area Governments. 1990. Provisional Series 3 projections, population,
housing, employment and land uses. San Francisco Bay region. Hotel Claremont, Berkeley,
California. .
BioSystems Analysis, Inc. (Biosystems). 1993a. Assessment of Special Status Plant and Animal
Species at Travis Air Force Base, Solano County, California. Phase II Surveys (Draft). August.
Biosystems. 1993b. Assessment of Habitat for Special Status Species at Travis Air Force Base,
California. October.
Biosystems. 1994. Vernal Pool Resources at Travis Air Force Base, Solano County. Final Report.
June.
California Department of Water Resources, Central District. 1994. Historical Ground Water
Levels in Solano County. March.
California Regional Water Quality Control Board (RWQCB). 1995. A Compilation of Water
Quality Goals. Prepared by Jon B. Marshack. July.
CH2M HILL. 1995. West/Annexes/Basewide Operable Unit Data Gaps Summary. Travis Air
Force Base, California. October 31.
CH2M HILL. 1996. Final Comprehensive Basewide Ecological Risk Assessment - Tier 2 Screening
Assessment, Travis Air Force Base, California. May 31.
CH2M HILL. 1997. West/Annexes/Basewide Operable Unit Remedial Investigation Report.
(Volumes 1-4), 60* Air Mobility Wing, Travis Air Force Base, California. May.
CH2M HILL. 1998. West/Annexes/Basewide Operable Unit Feasibility Study, 60* Air Mobility
Wing, Travis Air Force Base, California. April.
Freeze, R. Allen and John A. Cherry. 1979. Groundwater. Prentice-Hall, Inc., Englewood
Cliffs, N.J.
Jacobs Engineering Group (JEG). 1994a. Final Risk Assessment Protocol. Travis Air Force
Base, California. November.
Jacobs Engineering Group (JEG). 1994b. West/Annexes/Basewide Operable Unit, Draft
Preliminary Assessment, Travis Air Force Base, California. March.
Mayer, K. E. and W. F. Laudenslayer, Jr. 1988. A Guide to Wildlife Habitats of California.
California Department of Forestry and Fire Protection. Sacramento, California.
Olmsted F H. and G.H. Davis. 1961. Geologic Features and Ground-Water Storage Capacity
of the Sacramento Valley, California. Geological Survey Water-Supply Paper 1497.
Page, R.W. 1986. Geology of the Fresh Ground-Water Basin of the Central Valley, California, with
Texture Maps and Sections. U.S. Geological Survey Professional Paper 1401-C
Radian. 1994. Remedial Investigation/Feasibility Study Work Plan, North Operable Unit, Travis
Air Force Base, California. April.
RDD-SFO/980960015.DOC (uffi209.DOC)
-------
PABT II DECISION SUMMARY
Radian. 1996a. Final Groundwater Sampling and Analysis Program. Travis Air Force Base,
California. July.
Radian. 1996b. Final Remedial Investigation, West Industrial Operable Unit. Travis AFB,
California. February.
Radian. 1997. Groundwater Interim Record of Decision for the NEWIOU, Travis Air Force Base,
California.
Sims, J.D., K.F. Fox, J.A. Bartow, and EJ. Helley. 1973. Preliminary Geologic Map ofSolano
County and Parts ofNapa, Contra Costa, Marin, and Yolo Counties, California. U.S. Geologic
Survey.
State of California, Department of Finance. 1994. Population Estimates for California Cities
and Counties. Official State Estimates. Demographic Research Unit. Sacramento, California.
Thomasson, H.G., F.H. Olmsted and E.F. LeRoux. 1960. Geology, Water Resources and
Usable Ground-Water Storage Capacity of Part of Solano County, California, Geological
Survey Water-Supply Paper 1464.
Travis Air Force Base. 1998. Proposed Plan for Groundwater Cleanup. April.
U.S. Department of Commerce, U.S. Bureau of the Census. 1990. Census data.
U.S. Environmental Protection Agency (EPA). 1995. Region DC Preliminary Remediation
Goals (PRGs) Second Half 1995. September 1.
Wagner, D.L. and EJ. Bortugno. 1982. Geologic Map of the Santa Clara Quandrangle. California
Divisions of Mines and Geology.
Weston. 1993. Draft Final Work Plan Addendum, East Industrial Operable Unit, Travis AFB,
California. September.
Weston. 1995a. Final Basewide Ecological Habitat Assessment, Travis AFB, California. June.
Weston. 1995b. Final Remedial Investigation Report, East Industrial Operable Unit, Travis AFB,
California. October.
RDD-SFO/9809600J5.DOC{tNB209.DOC) 89
-------
PART III
Responsiveness Summary
The Air Force has promoted public input through the WABOU Groundwater Proposed Plan
and 8 April through 8 May 1998 public comment period. This Proposed Plan was issued to
the public just prior to the start of the public comment period. To encourage public
comment, the Air Force listed the phone numbers and E-mail addresses of Air Force and
DTSC representatives in the Proposed Plan, distributed copies of the Proposed Plan to local
libraries, and held a public meeting on 23 April 1998 at the Fairfield/Suisun Community
Center.
Several community members attended the public meeting, and oral comments were
received from one person: John Rundlett. No other comments were submitted to either the
Air Force or DTSC during the public comment period. A written transcript of the public
meeting contains the oral comments and is available for public review at the Travis AFB
Information Repository, located at the Vacaville Public Library. The oral comments
concerning the cleanup of contaminated groundwater in the WABOU at Travis AFB are
presented below and have been paraphrased for greater clarity. The selection of ground-
water remedial actions in the WABOU is based on the documents in the Administrative
Record and comments received from the public.
Public Comment 1: There was concern that there may be alternative technologies avail-
able that could be used to clean up the contaminated groundwater in the WABOU in a
more efficient or cost-effective manner.
Air Force Response: The Air Force is looking closely at the use of naturally occurring
processes to clean up contaminated groundwater. Known as Monitored Natural
Attenuation, this innovative technology relies on subsurface microorganisms that use the
groundwater contaminants as a source of energy. They break the contaminant molecules
down into harmless by-products.
Unfortunately, this technology has not been proven to be effective against all types of
groundwater contaminants. In the WABOU the only groundwater contaminants against
which Monitored Natural Attenuation may be effective are found at Building 755. This
technology is not applicable to the groundwater contaminants at the other three sites, so the
more established pump-and-treat technology is proposed for those sites. Also, the micro-
organisms have not been shown to be active and capable of preventing the future expansion
of the solvent plume at Building 755. As a result, the proposed interim groundwater
remedial alternative for this site includes the collection of groundwater data to demonstrate
the effectiveness of this .technology under, the site-specific conditions at Building 755. These
data will be used to select the final groundwater remedies for all of the contaminated
groundwater sites on Travis AFB.
Other innovative technologies were ruled out in the WABOU Feasibility Study, because
they were evaluated to be not effective under the site-specific conditions at Travis AFB.
RDD-SFO/980960015.DOC (lNB209.DOC) 9°
-------
PART ill RESPONSIVENESS SUMMARY
Public Comment 2: There was concern that the extraction and treatment of the contam-
inated groundwater would result in the accumulation of large drums of concentrated
contaminants that the Air Force would have to transport to an offbase dumpsite.
Air Force Response: The contaminants that are accumulated through the extraction and
treatment of contaminated groundwater will not be stored in drums at Travis AFB. For
example, one treatment method is to run the contaminated groundwater though an
activated carbon canister to remove the contaminants from the groundwater. The contami-
nant molecules attach themselves to the carbon material, allowing the cleaned water to flow
out of the canister. Afterward, the canister is sent to an appropriate offsite facility where the
contaminant molecules are stripped from the carbon and destroyed, and the carbon canister
is prepared for reuse. So, with this method, the contaminants are not in a concentrated form
and are not stored onbase for a long period of time. Another treatment option is to use an
oxidation system to physically destroy the contaminants in the groundwater. All of the
treatment options that were evaluated for use in the WABOU will result in the safe removal
of the contaminants. Drums will not be used to collect concentrated contaminants.
Public Comment 3: Will the contaminated groundwater have a negative impact on the
repair of the runways at Travis AFB?
Air Force Response: The groundwater sites in the WABOU are located far from the run-
ways, so the presence of this groundwater contamination and its treatment will not impact
the repair of the runways.
RDD-Sro/980960015.DOC(LNB209.DOC) . .91
-------
-------
APPENDIX A
Site Summary Figures
The figures in this appendix summarize the site-specific information for each West/
Annexes/Basewide Operable Unit (WABOU) groundwater site. Each summary contains
background and contaminant information from the WABOU Remedial Investigation report,
a brief description and estimated costs of the remedial alternatives mat were developed in
the WABOU Feasibility Study (FS), and a description of the selected interim groundwater
remedial action. It also includes a conceptual model of a cross section of the site and a
conceptual design of the selected alternative.
These figures were created to give the reader a snapshot of the characteristics of each site
and associated contamination that led to the selection of the remedial actions. For additional
information, Section 3.0 of this interim Record of Decision provides a more detailed descrip-
tion of the nature and extent of contamination and the calculated potential risks at each site.
Section 4.0 provides a more detailed description of the FS process and the detailed evalua-
tion of the remedial alternatives based on seven of the nine Comprehensive Environmental
Response Compensation and Liability Act (CERCLA) criteria. Tables 4-1 through 4-6
summarize the qualitative evaluation of the groundwater remedial alternatives against each
criterion. Table 4-7 provides the estimated cost of each remedial alternative at each site.
Section 5.0 provides a more detailed description of the selected remedial actions and the
rationale for their selection.
RDD-SFCW981280001.DOC {APPENOK.OOC)
-------
Building 755 (DP039)
Problem: Battery acid solutions and solvents were discharged from Building 755 into a sump and leach line resulting in
contamination of the subsurface soil and groundwater with VOCs. A groundwater TCE plume extends about 1,600 feet
downgradient of the site. The undissolved TCE beneath the water table may represent a conHnuing source of ground water
contamination. *
Site Description: Battery and Electric Shop
Groundwater Flow Direction: southeast
Depth to Ground water 23 feet bgsfjuly 1996)
Depth to Bedrock: about 49 feet bgs near Building 755
Primary Groundwater Contaminants and Associated Human Health Risks
Contaminant*
1.1 -OCE
TCE
1/Uxlmum
Concentration
7.800 M9rL
21 0.000 uol.
Total Potential
Cancer fllak
3x10-'
Maximum
Hazard Index
436
10
Primary
Contributor*
TCE
1,1 -OCE
Maximum
Concentnllon
210,000(104.
7,600119/1.
Selected Interim Remedial Action and Conceptual
Design Assumption
AltomaSve G3 and GS—Source Area Extraction/
Containment/Treatment Discharge
Ona 6-inch diameter dual phase extraction wen (5 gpm)
Fiv» 6-inch diameter PVC extraction walla (5 opm each)
Four 4-inch diameter PVC monitoring well pairs
Six 4-inch diameter PVC shallow monitoring wells
Ona 4-Inch diameter PVC deep monitoring well
Long-form monitoring of new wells plus 4 existing shallow wells
and 1 existing shallow piezometer
Six toil vapor piezometers
Long-term annual monitoring of new piezometers
Dual phase granular activated carbon treatment plant consisting
of two 50-Bpm disposable liquid phase carbon adsorbers and two
SOO-cfm disposable vapor phase carbon canisters
• Approximately 2.200 linear feet of subsurface influent pipeline,
1-Inch diameter. Class 200 PVC
• Approximately 900 linear feet of subsurface effluent pipeline.
3-Inch diameter. Class 200 PVC
• Discharge of treated groundwater to West Branch of Union Creek
BOO- VOMtiroOQZOOC (UCfllLl DOCl
Feasibility Study Alternatives and Associated Costs*
Alternative G1—No Action: $0
Alternative G2—Monitored Natural Attenuation: $510,300
Alternative G3—Containment/Treatment/ Discharge: $929.700
Alternative G4—Extraction/Treatment/ Discharge: $2,277,000
Alternative GS—Source Area and Ground-water
Extraction/TreatmenVMonitored Natural Attenuation: $4,950,000
• Alternative G6—Source Area Extraction/ Treatment/Monitored
Natural Attenuation: $7,406,000
•Prmnt Worn Coits buBd on 30 yaan md
5 pefcvnt dscount rets.
CONCEPTUAL DESIGN OF SELECTED ALTERNATIVES
CONCEPTUAL MODEL/CROSS SECTION
FIGURE A-1
BUILDING 755
SITE SUMMARY
WEST/«*J£XES«ASEW)DE OPERASLf UNlT(WABOUJ
WABOU GOUfJDWATHR tHOO
TRAVIS AIR FORCE BASE, CALIFORNIA
CH2MHILL
-------
Landfill 3 (LF008)
<~^^
Site Description: Landfill (inactive)
Groundwater How Direction: southeast to northwest
Depth to Groundwater; 25 to 35 feet bgs (July 1996)
Depth to Bedrock: about 65 feet bgs
Primary Groundwater Contaminants and Associated Human Health Risks
Contaminant*
heptacMor
•Ipta-cttkxdinc
iMptachlofapoxide
"Minium Total Potential
Concentration UncwrRltk
0.11 uo/L
0.084 uo/L
0.27 M9«.
0.033 uo/L
2X10-5
Maximum
Hard Index
1
Primary
Contributor*
na
Maximum
Concentration
na
Selected Interim Remedial Action and Conceptual
Design Assumptions
Alternative G4—ExtraotioiVTreatmenU Discharge
• Four 6-inch-diameter PVC extraction wells (5 opm each)
• Three 4-incb-diameter PVC monitoring well pairs
• Three 4-inch-diameter PVC shallow monitoring wells
• Long-term monitoring ol new weOs plus 4 existing shallow and
one existing deep well
• Liquid-phase granular activated carbon treatment at Building 755
• Approximately 2,800 linear feet ot subsurface effluent pipeline
2-inch-diameter PVC (to Building 7S5 for treatment)
HOO-SFOMiaTOOOZOOC ILJWnuj DOC)
DotnMUGNm»wawcu.itm)
CONCEPTUAL DESIGN OF SELECTED ALTERNATIVE
Feasibility Study Alternatives and Associated Costs*
• Alternative G1—No Action: $0
• Alternative G2—Monitored Natural Attenuation: $565.400
« Alternative G3—ContainroentfTreatment' Discharge: $582,300
• Alternative G4—ExtractkxvTreatment/Discharge: $819,800
•Fnna. Wort, 0«B land ca 30 yu» «xl 5 p«t«* dUcoint ral..
CONCEPTUAL MODEL
FIGURE A-2
LANDFILL 3
SITE SUMMARY
TRAVIS AIR FOflCE BASE, CALIFORNIA
- • - CH2MHILL.
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Building 905 (SS041 )/916 (SD043)
Building 905 Problem: Historical pesticides handling and equipment maintenance activities have resulted in contamination of the
surface soil and groundwater at the site. Elevated concentrations of organochlorine pesticides were found in the surface soil within
the fenced perimeter of the site and in the ground water underlying the facility.
Building 916 Problem: A former electrical power transformer containing a PCB isomer leaked and contaminated the soil and
groundwater at the site. The PCBs in the subsurface soil may represent a continuing source of groundwater contamination. In
addition, TCE was detected in the groundwater.
Site Description: Entomology Shop (Bldg. 905)/
Emergency Power Generation Facility (Bldg. 916)
Groundwater Flow Direction: south/southeast
Depth to Groundwater: 9 feet bgs (July 1996)
Depth to Bedrock: about 50 feet bgs
Primary Groundwater Contaminants and Associated Human Health Risks
Building
Bktg. 90S
Bldg. 9IS
Contaminants
heptachlor epoxido
PCB (ArocHor 1254)
TCE
Maximum
Concentration
0.023 ng/L
22uo/L
Tluort.
Total Potential
CanctrRUk
2x10-»
SxKr5
Maximum
Hazard Index
<1
22
Primary
Contributor*
na
PCB-1254
Maximum
Concentration
na
zapon.
bKtuM riix « ha Hun 10« « H« ml mdw it too Dun I.
Selected Interim Remedial Action and Conceptual
Design Assumption
Alternative G3 — Containment/Treatment/Discharge
• Ono 6-inch diameter extraction well (Sgpm)
• Two 4-inch diameter monitoring well pairs
• Thrco 4-inch diameters shallow monitoring wells
• Long-lorm monitoring of new wells plus 3 existing shallow wells
and 1 existing shallow piezometer
• Liquid-phase granular activated carbon treatment plant consisting
ol two 15-gpm DOT SB drum disposable carbon adsorbers
• Approximately 100 linear feet of subsurface influent pipeline.
1-inch diameter. Class 200 PVC
• Approximately ZOO linear feet of subsurface effluent pipeline.
1-Inch diameter. Class 20O PVC I
Aoo-sromi mcoo-ooc nwomu DCCJ
CONCEPTUAL DESIGN OF SELECTED ALTERNATIVE
Feasibility Study Alternatives and Associated Costs*
Alternative.GI—No Action: $0
Alternative G2—Monitored Natural Attenuation: $532,800
Alternative G3—ContainmenvTreatmenUDischarge: $568,100
•Prowl Worth Com butd on 30 y»w» «nd 5 (xmtnl cttcount r«t».
CONCEPTUAL MODEL
FIGURE A-3
BUILDINGS 9057916
SITE SUMMARY
WEST/ANNEXE9BASEWIDE OPERABLE UNIT
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Response to EPA Comments on the Draft Final WABOU Groundwater Interim ROD
The following revisions to the draft final WABOU Groundwater Interim ROD have been agreed
upon by all parties. The revisions are in bold type. The change pages based on^revisions-.1
through 5 were sent out to all parties on February 19,1998. The change pages based on revisions
6 and 7 are included with the final change pages distributed on June 24,1998.
1. We revised the second paragraph from the bottom of page 3 of Part 1 (Declaration,
Description of the Selected Interim Remedies) to read:
"In addition to the addendum to the NEWIOU Groundwater RD/RA Plan, the Air Force will
perform a pre-design investigation, as necessary, and then prepare a ^"^^SSL fa
work plan for each WABOU groundwater site. The purpose of the pre-design investigation is
to fill existing data gaps so that the Air Force can successfully implement the remedial
action aTasite. Examples of data gaps may include the distribution of groundwater
contamination in subsurface strata, hydrogeologic conditions that affect remedial ittbon
performance, and unusual groundwater analytical results that may indicate the presence of
additional groundwater contamination sources._The site-specific RD/RA work plan will
present the results of the site-specific pre-design investigation, the preliminary design
information including the potential placement of extraction and.momtonng wells,
groundwater monitoring protocols and frequency, and procedures to ^errmne whether plume
miration is occurring. After regulatory approval of the site-specffic RD/RA work plan the
Air Force will submit the RD design package that includes drawings, specifications, and a
design report. The site-specific RD/RA work plan and the RD desipi Package are P™"^
documente and are described in the final NEWIOU Interim Groundwater RD/RA Plan. If a
contingency action is necessary to control migration, the Air Force will request funding and
implement a contingency action as soon as funding becomes available."
We added the following sentences to the last paragraph in this section on page 4:
'Travis AFB will eventually replace this interim ROD with a final ROD as soon as sufficient data
has been collected to support the selection of a final remedy. The sites described in the final
NEWIOU Groundwater IROD and the WABOU groundwater sites may be addressed in one
basewide groundwater ROD if the Travis AFB Cleanup Team decides that this approach is
appropriate."
2. We revised the last paragraph in Section 3.3 (Chemicals of Concern) on page 36 to read:
"The approach to evaluating pesticide concentrations in the WABOU is based on comparisons
with the concentrations found at other locations on Travis AFB. The WABOU RI used the
Inorganic Constituent Evaluation Methodology (Radian, 1996b) to determine whether
compounds detected in samples are naturally occurring or are contaminants from past industrial
practices Statistical analysis of the pesticide detections from non-pesticide sites resulted in
the establishment of WABOU reference concentrations for pesticides. More detailed
discussion of the WABOU pesticide evaluation is provided in Appendix I of the WABOU Rl
report (CH2M HELL, 1997).
3. We revised section 4.3.1 (Overall Protection of Human Health and the Environment) to read:
"Overall protection of human health and the environment serves as a threshold determination that
must be met by any alternative for it to be selected as a remedy. Each of the groundwater
24 June 1999
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alternatives, except for Alternative Gl (No Action), are protective of human health and the
environment."
Also we deleted Table 4-2.
4. We revised the first paragraph of section 5.6 (Land Use Restrictions) to read:
"The Air Force has land use restrictions in place at the four WABOU groundwater sites. These
administrative actions restrict the use of onbase groundwater from these contaminated sites,
Travis AFB does not currently use its onbase groundwater for drinking water. These actions also
restrict soil excavation and other subsurface work where the excavation worker will encounter
contaminated groundwater or vapors. These subsurface activities are only allowed after
environmental and worker safety control measures are in place. Travis AFB uses its digging
permit program to coordinate, and if necessary, restrict contractor and Base personnel access to
contaminated areas. In addition, Travis AFB will amend its General Plan to document additional
land use restrictions, once the final remedial actions are selected in the basewide groundwater
ROD. A detailed description of the existing land use restrictions at the four WABOU
groundwater sites will be included in the addendum to the NEWIOU Groundwater RD/RA
Plan."
5. We added the following sentence in front of the last sentence of the subsection titled "Habitats
of Rare, Threatened, Endangered, and Special-Status Species" in section 6.4.2 (Location-Specific
ARARs) on page 63:
"U.S. EPA does not acknowledge that all CFGC requirements are more stringent than federal
requirements but concurs with the Air Force decision to comply with both federal and state
requirements as ARARs in this IROD."
6. We deleted the reference to Title 22 CCR 66264.97 as a Relevant and Appropriate
requirement in Table 6-3. This requirement was previously identified in Table 6-1 as Applicable,
and therefore was deleted from Table 6-3 to avoid confusion.
7. We revised the Source description of the NPDES requirements on the second page of Table 6-4
to read:
"Title 40 CFR Part 122 - EPA Administered Permit Programs: The National Pollutant
Discharge Elimination System (NPDES)"
24 June 1999
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