PB99-964505
EPA541-R99-045
1999
EPA Superfund
Record of Decision:
George Air Force Base OU3
Victorville, CA
10/5/1998
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SFUNO RECORDS CTR
3058-00099
SFUND RECORDS Ct
-< DM S# 48592
George Air Force Base,
California
Installation Restoration Program
Prepared for
Air Force Center for Environmental Excellence
Brooks Air Force Base, Texas
Contract F41624-92-D-8038
Final
Operable Unit 3 Record of Decision
November 1998
MONTGOMERY WATSON
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INSTALLATION RESTORATION PROGRAM
FINAL
RECORD OF DECISION
OPERABLE UNIT 3
GEORGE AIR FORCE BASE, CALIFORNIA
Prepared For:
U. S. Air Force Center for Environmental Excellence
Brooks Air Force Base
Contract No. F41624-92-D-8038
Delivery Order 004
Montgomery Watson Project No. 1212009.04090074
Prepared By:
Montgomery Watson
1340 Treat Boulevard, Suite 300
Walnut Creek, California 94596
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TABLE OF CONTENTS
Section Page
1.0 DECLARATION 1-1
1.1 SITE NAME AND LOCATION 1-1
1.2 STATEMENT OF BASIS AND PURPOSE 1-1
1.3 ASSESSMENT OFTHE SITE 1-2
1.4 DESCRIPTION OF THE SELECTED REMEDIES 1-2
1.5 STATUTORY DETERMINATIONS 1-2
1.6 APPROVED ... 1-4
2.0 DECISION SUMMARY 2-1
2.1 SITE NAME, LOCATION, AND DESCRIPTION 2-1
2.1.1 Description of Operable Units 2-1
2.1.2 Physical Characteristics of OU 3 2-3
2.2 SITE HISTORY AND ENFORCEMENT ACnVITIES 2-12
2.2.1 Base History 2-12
2.2.2 OU 3 Site Investigations 2-13
2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION 2-16
2.4 SCOPE AND ROLE OF OPERABLE UNIT WITHIN THE SITE
STRATEGY 2-17
2.5 LANDFILL SITE SUMMARY 2-18
2.5.1 Summary of Landfill Site Characteristics and Risk Assessments 2-19
2.5.2 Description of Landfill Site Alternatives 2-28
2.5.3 Summary of Comparative Analysis of Alternatives for the
Landfill Sites 2-33
2.5.4 The Selected Remedies for the Landfill Sites 2-43
2.5.5 Statutory Determinations for the Landfill Sites 2-50
2.6 TPH/VOC SITE SUMMARY 2-51
2.6.1 Summary of TPH/VOC Site Characteristics and Risk Assessments 2-52
2.6.2 Description of TPH/VOC Site Alternatives 2-62
2.6.3 Summary of Comparative Analysis of Alternatives for the
TPH/VOC Sites 2-69
2.6.4 The Selected Remedies for the TPH/VOC Sites 2-77
2.6.5 Statutory Determinations for the TPH/VOC Sites 2-86
2.7 SITE OT-69 SUMMARY 2-87
2.7.1 Summary of Site OT-69 Characteristics and Risk Assessment 2-88
2.7.2 Description of Site OT-69 Alternatives 2-91
2.7.3 Summary of Comparative Analysis of Alternatives for Site OT-69 2-93
2.7.4 The Selected Remedy for Site OT-69 2-100
2.7.5 Statutory Determinations for Site OT-69 2-101
2.8 DOCUMENTATION OF SIGNIFICANT CHANGES 2-103
2.9 CURRENT SITE STATUS 2-103
2.9.1 Landfill Sites 2-104
2.9.2 TPH/VOC Sites 2-107
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TABLE OF CONTENTS
(Continued)
3.0 RESPONSIVENESS SUMMARY 3-1
3.1 OVERVIEW 3-1
3.2 BACKGROUND ON COMMUNITY INVOLVEMENT 3-1
3.3 SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC
COMMENT PERIOD 3-2
REFERENCES
FIGURES
TABLES
APPENDICES
A - Action Items to Meet ROD Requirements
B - Criteria for Active Site Remediation - Site OT-69
C - Administrative Record
D - Responses to Agency Comments to April 1997 Draft ROD
E - Responses to Agency Comments to November 1997 Draft Final ROD
F - Responses to Agency Comments to February 1998 Draft Final ROD
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LIST OF FIGURES
(Figures are located at the end of the text)
Figure
No.
1 Vicinity Map
2 Operable Unit Site Locations
3 Regional Physiography
4 Major Hydrogeologic Features in the Mojave River Basin
5 Approximate Locations of Known Municipal and Domestic Water-Supply Wells,
GAFB Vicinity
6 Operable Unit 3 Feasibility Study Site Locations
7 Conceptual Diagram of Surface Controls/Rehabilitated Soil Cover, OU 3 Landfill
Sites
8 Conceptual Diagram of Capping Alternatives, OU 3 Landfill Sites
9 Remediation Goals for Soils at the OU 3 TPH/VOC Sites
10 Remediation Goals for TCE in Soils at Site FT-19c
11 Schematic of SVE System Design
12 Schematic Diagram of Soil Vapor Sampling From Monitoring Point
13 Schematic of Bioventing System Design
14 Site OT-69 Location Map
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LIST OF TABLES
(Tables are located at the end of the text,)
Table
1 Recommended Remedial Alternatives for OU 3 Sites
2 Summary of OU 3 Landfill Site Characterizations
3 Summary of Detailed Analysis of Remedial Alternatives for OU 3 Landfill Sites
4 ARARs for GAFB OU 3 Landfill Sites DP-03, DP-04, LF-12. LF-14, and the SEDA
5 Summary of Preliminary Remedial Alternative Costs for OU 3 Landfill Sites
6 Preliminary Cost Estimate for Site DP-03 Preferred Alternative
7 Preliminary Cost Estimate for Site DP-04 Preferred Alternative
8 Preliminary Cost Estimate for Site LF-12 Preferred Alternative
9 Preliminary Cost Estimate for Site LF-14 Preferred Alternative
10 Preliminary Cost Estimate for Site LF-44 Preferred Alternative
11 Preliminary Cost Estimate for the SEDA Preferred Alternative
12 Summary of Operable Unit 3 TPH/VOC Site Characterizations
13 Numerical Cleanup Standards for TPH/VOC Ground water Sites
14 Summary of Detailed Analysis of Remedial Alternatives for OU 3 TPH/VOC Sites
15 ARARs for GAFB OU 3 TPH/VOC Sites WP-17, FT-19a, FT-19b, FT-19c. OT-51, and
OT-69
16 Summary of Remedial Alternative Costs for OU 3 TPH/VOC Sites
17 Preliminary Cost Estimate for Site WP-17 Preferred Alternative
18 Preliminary Cost Estimate for Site FT-19a Preferred Alternative
19 Preliminary Cost Estimate for Site FT- I9c Preferred Alternative
20 Preliminary Cost Estimate for Site OT-51 Soils Preferred Alternative
21 Preliminary Cost Estimate for Site OT-51 Groundwater Preferred Alternative
IV
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LIST OF TABLES
(Continued)
Table
No.
22 Summary of Detailed Analysis of Remedial Alternatives for Site OT-69
23 Summary of Remedial Alternative Costs for Site OT-69 Groundwater
24 Preliminary Cost Estimate for Site OT-69 Preferred Alternative (G-2)
25 Summary of Current Remedial Alternative Costs for OU 3 Sites with Accelerated Actions
Performed
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ACRONYMS AND ABBREVIATIONS
AFBCA Air Force Base Conversion Agency
AFCEE Air Force Center for Environmental Excellence
ARAR applicable or relevant and appropriate requirement
bgs below ground surface
BTEX benzene, toluene, ethylbenzene, and xylene
CDWR California Department of Water Resources
CFR Code of Federal Regulations
CERCLA Comprehensive Environmental Response,"Compensation, and Liability Act
cfm cubic feet per minute
cfs cubic feet per second
COPC compound of potential concern
COPEC compound of potential ecological concern
CRP Community Relations Plan
DCA dichloroethane
DCE dichloroethene
DHS Department of Health Services
DTSC Department of Toxic Substances Control
EM electromagnetic terrain conductivity
ET evapotranspiration
FFA Federal Facilities Agreement
FML flexible membrane liner
FS Feasibility Study
FSRA Full Service Remedial Action
ft/day feet per day
ftVday square feet per day
ft/ft feet per foot
GAC granular activated carbon
GAFB George Air Force Base
gpd gallons per day
gpm gallons per minute
GPR ground penetrating radar
HVOC halogenated volatile organic compound
IRP Installation Restoration Program
IT International Technologies Corporation
JMM James M. Montgomery Consulting Engineers, Inc.
LRA Local Reuse Agency
LSA LSA Associates, Inc.
LUFT Leaking Underground Fuel Tank
M&E Metcalf & Eddy, Inc.
MAG magnetometry
MAP Management Action Plan
MCL Maximum Contaminant Level
pg/kg microgram per kilogram
pg/L micrograms per liter
mg/kg milligram per kilogram
mg/L milligrams per liter
VI
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ACRONYMS AND ABBREVIATIONS
(Continued)
mph miles per hour
ms! mean sea level
MWA Mojave Water Agency
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NEDA Northeast Disposal Area
NFA No Further Action
NPL National Priorities List
O&M operations and maintenance
ORC Oxygen Release Compound
OU Operable Unit
OVA organic vapor analyzer
PAH polynuclear aromatic hydrocarbon
PCB polychlorinated biphenyl
PCE tetrachloroethene
POL petroleum, oil, and lubricant
ppm parts per million
PRG Preliminary Remediation Goal
RAB Restoration Advisory Board
RAO remedial action objective
RCRA Resource Conservation and Recovery Act
RfD reference dose
RI Remedial Investigation
ROD Record of Decision
RPM Remedial Project Manager
RSA Regional Statistical Area
RWQCB Regional Water Quality Control Board
SAIC Science Applications Internationa] Corporation
SARA Superfund Amendments and Reauthorization Act of 1986
SCIA Southern California International Airport
SEDA Southeast Disposal Area
STP sewage treatment plant
SVE soil vapor extraction
SVOC semivolatile organic compound
TBC to-be-considered
TCA trichloroethane
TCE trichloroethene
TE toxicity equivalent
TMV toxicity, mobility, and volume
TPH total petroleum hydrocarbons
TRC Technical Review Committee
USAF U.S. Air Force
USEPA U.S. Environmental Protection Agency
USFWS U.S. Fish and Wildlife Service
USGS U.S. Geological Survey
UST underground storage tank
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ACRONYMS AND ABBREVIATIONS
(Continued)
UV ultraviolet
VOC volatile organic compound
VVEDA Victor Valley Economic Development Agency
VVWRA Victor Valley Wastewater Reclamation Authority
WPA Work Plan Addendum
WQPS Water Quality Protection Standards
vin
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CO
Section 1
MONTGOMERY WATSON
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1.0 DECLARATION
1.1 SITE NAME AND LOCATION
George Air Force Base
Operable Unit 3
San Bernardino County, California
1.2 STATEMENT OF BASIS AND PURPOSE
This decision document, a Record of Decision (ROD), presents the selected remedies for
Operable Unit (OU) 3 sites at George Air Force Base (GAFB), which were chosen in accordance
with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the administrative record for these sites and
complies with 40 Code of Federal Regulations (CFR), Part 300. The format of this ROD is
consistent with the guidance provided in the U.S. Environmental Protection Agency's
(USEPA's) "A Guide to Developing Superfund Records of Decision" (USEPA, 1990).
OU 3 consists of 60 Installation Restoration Program (IRP) sites. Each of the OU 3 sites and any
proposed remedies are listed on Table 1. These sites are distributed throughout the base and
range in size from a few hundred square feet to over 90 acres. The purpose of this ROD is to set
forth the remedial actions to be conducted to remediate OU 3 IRP sites that were presented in the
OU 3 Feasibility Study (FS) Report (Montgomery Watson, 1997a) and to document the selection
of no further action (NFA) as final closure for the remaining OU 3 IRP sites.
The sites addressed in the OU 3 FS are presented in this ROD in two groups: 1) landfill sites
(DP-03, DP-04, LF-12, LF-14, LF-35, LF-44, and the Southeast Disposal Area [SEDA][the
SEDA remediation boundary includes nine separate sites]) (referred to as "landfill sites" in this
ROD); and 2) sites affected by total petroleum hydrocarbons (TPH) and/or volatile organic
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compounds (VOCs) (WP-17, FT-19a, FT-19b, FT-19c, FT-20 [soil], OT-51, SS-59, and OT-69)
(referred to as 'TPH/VOC sites" in this ROD). The TCE detected in groundwater in monitoring
wells in the vicinity of Site FT-20 (groundwater) is currently associated with the groundwater
contamination at OU 2. Therefore, final decisions regarding potential actions at Site FT-20
(groundwater) will be determined in the OU 2 ROD. The remaining OU 3 sites are
recommended for NFA (see Table 1).
The U.S. Air Force (USAF), USEPA Region IX, and the State of California concur with the
selected remedies.
13 ^ ASSESSMENT OF THE SITE
Actual or threatened releases of pollutants and contaminants from the landfill sites and
TPH/VOC sites, if not addressed by implementing the remedial actions presented in this ROD,
may present a risk to public health, welfare, or the environment. The remaining sites are
recommended for NFA (see Table 1).
1.4 DESCRIPTION OF THE SELECTED REMEDIES
Based on remedial investigations and alternatives evaluated in the OU 3 FS (Montgomery
Watson, 1997a), the USAF determined the final action for the 60 OU 3 IRP sites addressed in
this ROD as summarized in Table 1. The determination of these final actions was achieved with
the concurrence of the USEPA and the State of California. Section 2.0 provides further details
describing the remedies for sites requiring action. Risk assessment and remedy selection
considered reuse. As a result, selected remedies are compatible with intended property reuse.
The selected remedy for the affected specific parcel will be reviewed with the local reuse agency,
prior to a transfer, to ensure that it remains compatible with reuse.
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1.5 STATUTORY DETERMINATIONS
The selected remedies (Table 1) are protective of human health and the environment, comply
with federal and state requirements that are legally applicable or relevant and appropriate to the
remedial actions, and are cost-effective. The remedies utilize permanent solutions and
alternative treatment technology to the maximum extent practicable for these sites. The remedies
for the TPH/VOC sites satisfy the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, and volume (TMV) as a principal element. However, because
treatment of the principal threats of the landfill sites was not found to be practicable, the
remedies for the landfills do not satisfy the statutory preference for treatment as a principal
element.^ A review of this ROD will be conducted every 5 years to ensure that the remedies
continue to provide adequate protection of human health and the environment.
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1.6
APPROVED
ALBERT F.
Director
Air Force Base Conversion A^gency
Date
Concurrence
Chief, Federal Facilities Cleanup ;Branch
Environmental Protection Agency
Region:
JOHN E. SCAlgpURA
-hief, Southern California Operations
Office of Military Facilities
Department of Toxic Substances Control
f
HAROLD SINGER J
Date
Date
Executive Officer
California Regional Water Quality Control Board
Lahontan Region
Date
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§
Section 2
MONTGOMERY WATSON
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2.0 DECISION SUMMARY
This decision summary provides a description of OU 3 including the regional setting,
physiography, meteorology, demography and land use, hydrology, hydrogeology, and water use.
This section also summarizes the problems posed by the conditions at OU 3, the remedial
alternatives, and the rationale for the selection and how the selected remedy satisfies statutory
requirements.
2.1 SITE NAME, LOCATION, AND DESCRIPTION
GAFB encompasses an area of approximately 5,347 acres and is located in San Bernardino
County in the western Mojave Desert near the cities of Victorville and Adelanto, California.
Victorville is located on Interstate 15, approximately 70 miles northeast of the City of Los
Angeles, 35 miles north of San Bernardino, and 31 miles south of Barstow (Figure 1). In
evaluating environmental conditions at GAFB, all identified sites have been combined into three
OUs based on the type of waste present and the geographical location (Figure 2).
2.1.1 Description of Operable Units
OU 1 consists of three sites: (1) Site SD-25 (S-20), an Industrial/Storm Drain which in the past
received industrial waste; (2) Site WP-26 (S-21), the former sewage treatment plant (STP)
percolation ponds; and (3) the dissolved TCE plume detected in the groundwater beneath the
northeast portion of the base and adjacent off-base areas. A ROD has been finalized for OU 1
(Montgomery Watson, 1994).
OU 2 consists of six sites: (1) Site SS-30, a free-phase JP-4 jet fuel plume identified beneath the
Operational Apron; (2) Site ST-54, a pipeline leak near Building 708; (3) Site ST-57, Fuel Pit
No. 1; (4) Site SS-58, the underground storage tank (UST) complex at Building 690; and (5) Site
ST-67, the entire Liquid Fuel Distribution System, including five aboveground tanks, two major
pipelines (8-inch and 10-inch), and all hydrants (Fuel Pits 1 through 7) and associated piping.
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and (6) FT-20 (groundwater), TCE detected in the groundwater in the vicinity of the old sewage
treatment plant percolation ponds.
OU 3 consists of the 60 remaining IRP sites located throughout GAFB. The OU 3 sites consist
of a variety of potential contaminant source areas including landfills, other waste disposal and
storage sites, fire training areas, spill sites, and leachfields. Table 1 presents a summary of all
OU 3 IRP sites. These sites are distributed throughout the base and range in size from a few
hundred square feet to over 90 acres. These sites have been designated as disposal pit (DP), fire
training area (FT), landfill (LF), radiological waste (RW), spill site (SS), waste pit (WP), or
"other" (OT). The remedial investigations and site characterizations for the OU 3 sites are
detailed in the OU 3 Remedial Investigation (RI) Report (Montgomery Watson, 1996a). This
ROD presents the final decision for closure of all OU 3 IRP sites.
The pesticide dieldrin has been detected in monitoring wells in the eastern portion of the base in
the vicinity of the former residential housing area (i.e., monitoring wells NZ-63, NZ-64, and NZ-
66) (Montgomery Watson, 1996a and 1997d). These detections are not currently associated with
OU 3 and will be addressed as part of another OU; therefore, the are not addressed as part of this
OU 3 ROD. The manner in which these detections are addressed is to be determined based on
discussions between the Remedial Project Managers (RPMs) for the USEPA, the California
Department of Toxic Substances Control (DTSC) (formerly the California Department of Health
Services [DHS]), the Lahontan Regional Water Quality Control Board (RWQCB), and the
USAF.
Based on the OU 3 remedial investigations, the "landfill sites" and the 'TPH/VOC sites" were
assessed for remedial actions as detailed in the OU 3 FS Report (Montgomery Watson, 1997a);
the remaining sites were recommended for NFA. Table 1 lists all OU 3 sites and documents the
sites for which NFA is recommended. The discussions that follow regarding OU 3 sites refer to
the sites that require some form of remedial action (i.e., the landfill sites and TPH/VOC sites).
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2.1.2 Physical Characteristics of OU 3
The 60 OU 3 IRP sites arc located throughout GAFB. The area immediately surrounding the
base is the Victor VaJley portion of the Upper Mojave River Basin. The regional
geomorphology, surface water hydrology, geology, hydrogeology, regional planning, and
ecology of GAFB and the surrounding area are discussed in detail in the OU 3 RI Report
(Montgomery Watson, 1996a) and are summarized below.
2.1.2.1 Regional Physiography. GAFB is located in the Mojave Desert physiographic
province of California. Locally, the base lies within a wedge-shaped tectonic block in the
south-central portion of the Mojave Desert, flanked by the Sierra Nevada Mountains to the
northwest, the Radman and Cady Mountains to the northeast, the San Gabriel Mountains to the
southwest, and the San Bernardino Mountains to the southeast (Figure 3). The local region is
comprised predominantly of northward sloping alluvial fan deposits derived from the
surrounding mountains, and recent deposits associated with the Mojave River. Regional
elevations reach as high as 8.500 feet (near Crestline), where annual precipitation typically is
more than 40 inches. In contrast, the terminus of the Mojave River at Soda Dry Lake (elevation
923 feet) south of Baker receives 3 inches of precipitation annually. Elevations in the vicinity of
GAFB range from 2,650 feet at the northeast corner of the study area, to 2,920 feet at the
southwest comer of the base, south of Air Base Road. The average elevation at GAFB is
approximately 2,750 feet, with average slopes of approximately 2 to 4 percent to the northeast.
The base is relatively flat except at the eastern edge, where the surface elevation drops
approximately 200 feet to the Mojave River. The average elevation of the Mojave River flood
plain immediately east of the base is approximately 2,580 feet (Montgomery Watson, 1996a).
The Mojave River flows along the east side of GAFB in a northwesterly direction. Communities
within the Victor Valley area include the city of Adelanto, directly west and adjacent to GAFB,
the city of Victorville directly .southeast, and Oro Grande, Silver Lakes, Apple Valley, and
Hesperia. The Victor Valley Wastewater Reclamation Authority (WWRA) treatment plant is
located approximately one-half mile north of the northern border of GAFB.
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2.1 JU2 Meteorology. The climate in the GAFB area is typical of the high desert region
of California and Nevada. The summers are hot and dry, with maximum daily temperatures
often exceeding 100°F in July and August. Winters are cool and dry and nighttime temperatures
often fall below freezing in December and January (SAIC, 1987). The annual average
temperature is 62°F.
Based on Air Force records from 1942 to 1992, annual precipitation at GAFB ranges from 0.77
inch to 11.22 inches, with an average annual precipitation of 5.72 inches (Montgomery Watson,
1996a). Monthly precipitation typically ranges from 0.25 inch to 4.47 inches, with the period
from January through March being the wettest. During storm events, daily precipitation may
reach as much as 2.93 inches. Snowfall is infrequent, but may total a few inches per year and
was recorded to be as high as 17 inches in 1974. The average annual potential evapotranspiration
(ET) rate is about 83 inches (SAIC, 1987), far exceeding average annual precipitation.
Prevailing winds in the area of GAFB are from the south; however, the strongest gusts are
typically from the west. Westerly gusts of 50 miles per hour (mph) or more usually occur in the
spring. In the summer, strong southerlies blow over the San Bernardino Mountains (Cajon Pass)
in the evenings. Northerly winds occur more frequently in the fall and winter months (SAIC,
1987).
2.1.2-3 , Demography and Land Use. GAFB is located within Census Tract 91.02, and
Regional Statistical Area (RSA) 32B of San Bernardino County (US Census Bureau). RSA 32B
also includes the cities of Adelanto, Hesperia, and Victorville and the unincorporated
communities of Phelan, Apple Valley, and Lucerne Valley. According to the closure documents
for GAFB, the estimated combined GAFB military and civilian work force on base in mid-1992
was 3,725. However, because the base closure in December 1992, there no longer arc permanent
residents on base. The following are 1994 estimated populations of the surrounding cities and
communities, according to their respective city offices or San Bernardino County (Montgomery
Watson, 1996a):
Adelanto 13,000
Apple Valley 53,450
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Hesperia 58,050
Lucerne Valley 10,000
Oro Grande 430
Phelan 15,000
Silver Lakes 3,000
Victorville 57.830
TOTAL 210,760
The Victor Valley area has experienced significant population growth in the past two decades.
Between 1970 and 1980, the number of residents in RSA 32B increased approximately 70
percent (SAIC, 1987). Population growth in the area is projected to be approximately 5 percent
annually until 2010 (USAF, 1992). The projected annual growth figures may be greater than 5
percent depending on the ultimate reuse of GAFB.
The major land use activities of the Victor Valley area include residential development,
government and commercial services, cement manufacturing, railroad and highway
transportation, localized agricultural activities along the Mojave River, and industrial mining in
the outlying areas. The California Aqueduct carries water across the high desert approximately 5
miles south of the base and may impact long-term land use planning. A major fuels distribution
pipeline parallels Air Base Road for half the length of the base, and a high-voltage transmission
utility corridor crosses the southeast comer of the base.
GAFB was established during World War n and provided the foundation for a steady economic
base for the Victorville, Adelanto, and Apple Valley areas. Until 1992, GAFB was the largest
employer in the Victorville area. Residential and commercial development and growth of
community services was, in large part, due to the presence of the base. Despite the recent base
closure, the climate and recreational attractions within the region continue to contribute to the
development of vacation and/or second homes as well as the expansion of retirement
communities. Growth in the Victor Valley also has been impacted as increasing numbers of
people move to the area seeking to avoid the congestion and high cost of living in the Los
Angeles Basin.
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The proposed action for reuse of GAFB is development of an international airport and a
commercial, industrial, and business park development. The Local Reuse Agency (LRA) and the
Victor Valley Economic Development Agency (VVEDA) has designated the airport as the
Southern California International Airport (SCIA). There are currently light industry and
commercial companies using the facilities. There are no current plans for residential
development on former base property (CRSS Constructors, Inc., 1996). The above reuse was
considered during the development of risk assessments and remedy selection. As a result, the
selected remedies are compatible with reuse. The selected remedy for the affected specific parcel
will be reviewed with the local reuse agency, prior to a transfer, to ensure that it remains
compatible with reuse.
2.1.2.4 ^ Hydrogeology. GAFB is located in the George Groundwater Sub-Basin which is
a sub-basin of the Upper Mojave River Basin. The George Sub-Basin reportedly is a structural
trough containing up to 3,000 feet of alluvial sediments in the deepest parts of the basin. The
depth to bedrock is estimated to be approximately 1,350 feet below ground surface (bgs). Water
level and lithology data have been used to identify two distinct water-bearing zones in the GAFB
area: a shallow "Upper Aquifer" and a deeper "Lower Aquifer," separated by the "Aquitard."
The Upper Aquifer is a zone of saturated, highly to moderately permeable, interbedded silty
sands, poorly sorted sands, silts, and clays. Pumping test data indicate that the Upper Aquifer
has transmissivities ranging from 7 square feet per day (ftVday) to 2,400 ftVday and hydraulic
conductivities ranging from less than 0.01 feet per day (ft/day) to 35 ft/day. Groundwater
elevations within the area range from approximately 2,680 feet above mean sea level (msl) in the
northeastern portion of the base to 2,760 feet above msl in the southwest. The general
groundwater flow direction typically varies from the north to northeast with a hydraulic gradient
of approximately 0.003 feet/foot (ft/ft). North of the base, the groundwater gradient increases to
0.01 towards the northeast. The Upper Aquifer exists beneath GAFB; however, it terminates to
the north and eastern portion of the base. The saturated zone is up to approximately 80 feet thick
and thins to a thickness of zero where the aquifer terminates.
The Aquitard, consisting of interbedded very low to low permeability clays and silts, is present
from approximately 2,650 feet above msl to 2,740 feet above msl and is approximately 20 to 40
feet thick. The Aquitard is believed to have been deposited in a lake-filled basin which
historically occupied the vicinity of GAFB. The Aquitard hydrauiically separates the Upper and
Lower aquifers but is not continuous north of the base and east of the area along the Mojave
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River bluffs. However, the Aquitard is continuous to the west and southwest as determined by
investigation activities performed for OU 1 (Montgomery Watson, I995b), OU 2 (IT, 1992), and
OU 3 (Montgomery Watson, 1996a). The lack of hydraulic communication between the aquifers
through the Aquitard is supported by a zone of unsaturated moderately permeable materials
encountered below the Aquitard and above the Lower Aquifer and dry clays within the Aquitard
encountered in well borings during investigations for OU 1, OU 2, and OU 3. Geotechnical
testing has indicated hydraulic conductivities of Aquitard silts and clays ranging from 3.1E-4
ft/day to 1.7E-3 ft/day (Montgomery Watson, 1995b). Where the Upper Aquifer terminates to
the north and east of the area, the lateral edge of the Aquitard has been inferred.
The Lower Aquifer is present beneath the entire base and generally consists of interbedded sands,
gravelly sands, and silts with minor caliche beds. Groundwater elevations in the Lower Aquifer
within the area range from 2,590 to 2,584 feet above msl. The gradient in the central portion of
the base is 0.0002 ft/ft and increases to 0.001 ft/ft toward the east. Pumping test data indicate
that the Lower Aquifer has transmissivities ranging from 170 ftVday to 6,000 ftVday and
hydraulic conductivities that may exceed 80 ft/day based on an assumed aquifer thickness of 100
feet. The Lower Aquifer is geographically extensive and is hydraulically associated with the
Mojave River Aquifer. The Mojave River Aquifer occupies the river channel sediments east of
the base. The Mojave River deposits overlie and are interbedded with older Lower Aquifer soils.
This unit is relatively transmissive and provides good quality water to regional wells.
Potentiometric contours of the Lower Aquifer are perpendicular to the directions of flow in the
Mojave River. Therefore, groundwater flow in the Mojave River and Lower aquifers are
parallel.
2.1.2.5 Surface Water Hydrology. The Mojave River is the major surface drainage in
the Victor Valley. The Mojave extends for approximately 125 miles from its headwaters at the
Mojave Forks in the San Bernardino Mountains to its terminus at Soda Dry Lake south of Baker
(Figure 4). The river drains an area over 3,000 square miles (USAF, 1992). East of GAFB, the
river flows northward, coming as close as approximately 1,500 feet from the northeast corner of
the base. Surface flow in the Mojave River through most of the Victor Valley typically occurs
only during heavy rainstorms. In the Upper Mojave River Basin, however, perennial flow occurs
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for approximately 1 mile below the Mojave Forks because of the perennial flow of Deep Creek
(which merges with the Mojave at its headwaters), and again near Victorville through the Upper
Narrows and the Lower Narrows. The Narrows are formed by a bedrock ridge that creates a
subsurface flow barrier, causing river underflow to rise to the ground surface. U.S. Geological
Survey (USGS) topographic maps and aerial photographs indicate that, historically, surface flow
continued downstream as far as Bryman, 8 miles north of GAFB. Today, surface flow persists
only approximately 1 mile below the Lower Narrows, except during and shortly after heavy
rainfall. Regional withdrawal of groundwater apparently has lowered the Mojave River
underflow in the vicinity of GAFB.
Daily mean discharge values of the Mojave River through the Lower Narrows during 1993
ranged from 3 to 13,800 cubic feet per second (cfs), with an average daily discharge of 394 cfs.
Daily discharge in 1993, a very wet year, averaged nearly 28 times greater than 1990 values
(Montgomery Watson, 1996a). Discharge records maintained since 1899 indicate an average
discharge of 75.2 cfs, with a maximum discharge of 70,600 cfs recorded March 2, 1938 (USGS,
1992).
East of GAFB, the Mojave River has cut a channel approximately 1 mile wide and 200 feet deep.
No perennial streams are located within the boundaries of GAFB. Rainfall generally percolates
into the topsoil, collects in low areas and evaporates, or discharges through small natural
channels. Surface water from GAFB drains predominantly to the northeast and east. Runoff
from the flight line and the industrial and office areas is directed through roadways, storm drains,
culverts, and ditches to the Outfall Ditch on the northeast side of the base. Flow from this
drainage ditch reaches the Mojave River only during heavy storms. Runoff from the eastern
residential areas discharges through small natural gullies located to the north and east. This
runoff travels north and east toward the Mojave River wash. Much of the southern part of the
base drains northward into the industrial and flight line runoff system. Intermittent surface flow
on the western half of the base discharges north-northwestward into tributaries that discharge to
the Mojave River near Helendale.
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A large, north-trending arroyo dissects the northeast section of the base. The arroyo channel is
approximately 15 feet wide near the northern base fence line and 100 feet wide where the arroyo
discharges into the Mojave River wash. It was formerly fed by the Outfall Ditch from the base,
numerous gullies, and a smaller drainage ditch that originates from the Fire Training Area. The
arroyo intermittently receives treated effluent from the OU 1 groundwater extraction and
treatment system. This water percolates into the subsurface just north of the base boundary and
before the arroyo discharges to the Mojave River wash.
Discharge sources into the Mojave River upstream of GAFB are limited to agricultural and
recreational uses and several fish hatcheries. East of GAFB, the Riverside Cement Plant
discharges cooling water into the Mojave River Channel. The VVWRA sewage treatment
facility northeast of GAFB discharges treated water directly into the Mojave River wash east of
the plant. Although annual discharge volumes vary, they have been steadily increasing. Data
supplied by the VVWRA indicate that during 1993, the treatment plant discharged an average of
approximately 5 million gallons per day (gpd) into the Mojave River, and another 1 million gpd
through its percolation ponds (Montgomery Watson, 1996a).
2.1.2.6 Water Use. Water usage includes domestic, industrial, and agricultural. The per
capita rate of water demand has been estimated to be 200 to 285 gpd (SAIC, 1987). Because of
arid conditions and lack of surface water bodies in the Upper Mojave River Valley Groundwater
Basin, groundwater has been the principal source of water used in the Victor Valley desert
communities. The Mojave Water Agency (MWA) oversees the adjudication of groundwater
within the Mojave River Groundwater Basin. Consumptive groundwater usage in the Upper
Mojave River Groundwater Basin (the MWA's "Alto" portion of the basin) in 1990 was
estimated to be 89,400 acre-feet. The projected annual consumption for the year 1995 was
94,500 acre-feet.
Population increases in the study area caused domestic water demand to almost double during the
period between 1973 and 1983 (SAIC, 1987), and double again between 1983 and 1994
(Montgomery Watson, 1996a). The increase in demand has led to overdraft conditions (water
removed from the basin but not replenished) within the Mojave River Groundwater Basin.
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Groundwater overdraft in the Upper Mojave River Basin for the years 1990 and 1995 is
estimated to be 19,900 and 25,000 acre-feet, respectively (Montgomery Watson, 1996a).
Groundwater consumption in the George Groundwater Sub-basin has not been specifically
tracked by the MWA; however, tracking by smaller use areas is being pursued as groundwater
overdraft in the region continues to be a concern.
As of 1990, the MWA has been entitled to 50,800 acre-feet per year of water from the California
Water Project. However, due to recent statewide drought conditions, the MWA has not yet been
allotted their full entitlement. Once allotted, the MWA plans to begin utilizing their water
entitlement to directly recharge groundwater in the Mojave River Basin (Montgomery Watson,
1996a).
Limited information is available concerning supply wells on and in the vicinity of GAFB.
Available data indicate the existence of off-base wells beyond the northeast corner of the base,
below the southeast corner of the base, and along the Mojave River beyond the eastern base
boundary (Figure 5).
Two supply wells owned by the VVWRA are located northeast of the base. These two wells are
reported to be screened at depths of 65 to 75 feet bgs with pumping capacities of 500 gallons per
minute (gpm) each. Based on the location and approximate elevations of the wellheads, these
wells are believed to be screened in the Mojave River Aquifer. The groundwater table was
measured at 36 feet bgs. Groundwater from these WWRA wells is used only for non-potable
and industrial applications, while bottled drinking water is supplied for workers at the plant
(Montgomery Watson, 1996a).
According to the records maintained by the California Department of Water Resources (CDWR),
four production wells exist southeast of the base (Figure 5). The production capacities of these
wells range from 100 to 1,200 gpm. The wells are screened to depths ranging from 500 to 610
feet bgs, and may be screened in a deeper and possibly different aquifer system than the
monitoring wells installed at GAFB in the Lower Aquifer.
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Currently, seven production wells supply water to both GAFB and the adjacent city of Adelanto.
An eighth well was closed when production rates declined. Water elevations indicate that these
wells are screened below or in the deeper portions of the Lower Aquifer (Boyle. 1987). All of
the production wells are located near the Mojave River beyond the eastern base boundary, on the
west side of the Mojave River in Section 30 T6N, R4W, just north of the Lower Narrows (Figure
5). Five of the seven water supply wells near GAFB operated while the base was active;
however, production rates since base closure are not known. These wells will likely be used to
service the future uses of the base property.
Three additional wells are located northeast of GAFB production wells along the eastern bank of
the Mojave River (Figure 5), and supply water to the town of Oro Grande.
It is suspected that privately owned wells and smaller capacity domestic and irrigation wells in
the vicinity draw from the Upper Aquifer.
2.1.2.7 Vegetation. The most predominant type of vegetation is the creosote bush scrub
community, which includes creosote bush, cheesebush, burroweed, ricegrass, and Mormon tea.
This type of vegetation is typically found in the undeveloped areas of the base. Russian Thistle,
or tumbleweed, is often found in the disturbed areas. Riparian (associated with water) vegetation
communities including cottonwoods, willows, cattail rushes, and sedges are found along the
Mojave River channel, near the base golf course and the former GAFB STP percolation ponds
(Montgomery Watson, 1996a).
A biological assessment was conducted in 1989 in the northern portion of the base and in an
off-base section just north of the northern base boundary. This assessment was done as part of
the initial FS for the Northeast Disposal Area (NEDA) (JMM, 1988). The dominant plant
species found were creosote bush, sweetbush, cheesebush, paperbag bush, and indigo bush, all
Mojave Desert creosote bush scrub. Golden cholla cactus, beavertail cactus, and pencil cholla
were also found scattered throughout the site. Herbaceous plants included introduced grasses
such as abu-mashi and red brome, as well as native grasses and herbs such as Indian ricegrass.
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spurge, chia, and fiddlencck. Joshua trees occur along the base of the steep slopes in the area
(LSA, 1989).
Several sensitive plant species may occur in the area of GAFB. Good habitat exists for several of
the plant species; however, only Joshua trees were actually observed during the survey of the
area (LSA, 1989). Additionally, the U.S. Fish and Wildlife Service (USFWS) lists three
Category-2 species that may be present on GAFB. These are the alkali mariposa lily, Bars tow
woody sunflower, and the desert cymoperus. Category-2 species are those for which existing
information is insufficient to warrant listing as endangered or threatened species (USAF, 1989).
2.1.2.8 Animal Life. Animal life in the vicinity of GAFB includes both desert and
riparian species such as black-tail jackrabbit, cottontail rabbit, and antelope ground squirrel
(Montgomery Watson, 1996a). Seventy-five bird species have been identified in the area,
including ravens, hawks, owls, quail, flycatchers, larks, warblers, sparrows, and blackbirds.
Other wildlife includes lizards, snakes, pocket mice, raccoons, and coyotes. Generally, animal
activity is highest in the northern and southern portions of the base where native plants are least
disturbed. Animal activity typically has been lowest in the high traffic areas of the base, such as
the housing and industrial complex, the recreation areas, and the runways (USAF, 1989);
however, it is likely that some activity and reinhabitation has occurred since base closure.
The desert tortoise is the only animal species found on the base that is listed by the USFWS as a
threatened or endangered species. Two Category-2 animal species that may be present on GAFB
are the ferruginous hawk, and Mojave ground squirrel (USAF, 1989).
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2J2.1 Base History
GAFB is a 5,347-acre facility constructed between 1941 and 1943. GAFB was commissioned as
a flight training school. With flight training as primary activity at GAFB throughout its history,
bombardier and glider, single- and twin-engine, and jet flight training schools were all
*
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accommodated on the base at various times. Over the years, a wide variety of aircraft has been
stationed at GAFB.
To effectively carry out the primary mission of pilot training, GAFB engaged in a variety of
support operations such as aircraft maintenance and fire fighting training, that required the
handling, use, and disposal of hazardous and non-hazardous materials.
Since 1980, the USAF has had an active environmental cleanup program which is currently
known as the IRP. The purpose of the IRP at GAFB is to protect human health and the
environment by identifying and cleaning up environmental contamination resulting from past
disposal practices. The cleanup at GAFB is being conducted under the requirements of
CERCLA. Section 120 of CERCLA states that the facilities must investigate and remediate, if
necessary, past releases of hazardous waste.
In December 1988, GAFB was informed that it would be decommissioned as an Air Force base
in December 1992. In February 1990, the USEPA added GAFB to the Superfund National
Priorities List (NPL).
In October 1990, GAFB signed a Federal Facilities Agreement (FFA) with USEPA Region DC,
the DTSC, and the Lahontan RWQCB. The three OUs were created with the signing of the FFA.
The base was formally closed on December 15, 1992.
2J2.2 OU 3 Site Investigations
RI/FS activities at GAFB began in 1981 when the USAF performed a records search to identify
possible contaminated sites and potential problems that may result from contaminant migration
from these sites (CH2M Hill, 1982). Since 1981, the USAF has performed investigations in an
effort to confirm the presence of potential contamination at sites identified during the records
search and to define the extent of contamination at these sites.
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The first preliminary study conducted under the ERP at GAFB was completed in January 1982.
This study was a Phase I records search and was based on a review of available records
pertaining to chemical handling and disposal practices, interviews with site personnel, and a site
survey of activities at many sites within GAFB. The 1982 report indicated that potentially
hazardous waste from past activities was stored and disposed at GAFB (CH2M Hill, 1982).
In 1992, a work plan was prepared for OU 3 (JMM, 1992). This work plan summarized the
historical information for all known OU 3 sites including the results of any prior investigations.
The OU 3 Work Plan Addendum (WPA) assessed historical information, the Phase 1 records
search (CH2M Hill, 1982), and subsequent site inspections. Based on this assessment, the WPA
recommended NFA for 20 sites determined not to pose a threat to human health or the
environment and presented the recommended remedial investigation activities for the remaining
OU 3 sites.
The OU 3 remedial investigation activities began in 1992. Of the 60 OU 3 IRP sites that make
up OU 3, no further investigation was required at the 20 sites designated as NFA in the OU 3
WPA (JMM, 1992), land use restrictions were recommended for Site LF-35 in the WPA, and the
remaining sites were investigated. Of the sites investigated, Montgomery Watson investigated
27 IRP sites; Metcalf & Eddy (M&E) investigated eight sites; Montgomery Watson and M&E
investigated two sites, and International Technologies Corporation (IT) investigated two sites.
Table 1 summarizes this information. The 20 sites recommended as NFA in the WPA included
one site located in the SEDA (LF-11) and three sites (DP-02, LF-43, and LF-45) associated with
OU 3 sites that were investigated by Montgomery Watson. The OU 3 RI Report presented
results from the OU 3 remedial investigations including cumulative basewide human health and
ecological risk assessments.
The primary objective of the OU 3 RI was to obtain sufficient information to support an
informed decision regarding the most appropriate future action at each site. Specific objectives
of the RI report included identification of the extent of contamination, analysis of the fate and
transport of contaminants, and development of a baseline risk assessment.
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Specific field investigation activities included aerial ground penetrating radar (GPR) surveys,
surface GPR surveys, boundary confirmation borings, soil-gas surveys, surface and subsurface
soil sampling, test pit excavations, soil borings, monitoring well installation, downhole
geophysics, aquifer testing, monitoring well sampling, geotechnical sampling, HydroPunch®
sampling, record searches, biological testing, dioxin testing, surface mapping, and a radiological
survey.
To help identify compounds of potential concern (COPCs), background concentrations were
established for inorganics in soil and groundwater. Detected organic compounds were not
considered to be naturally occurring and, therefore, were considered to be above background.
Vadose zone contaminant migration modeling (SESOIL) was performed under hypothetical
worst case conditions to estimate potential impacts to groundwater. For most sites modeled,
results suggested that the most mobile constituents detected in soils would migrate less than 20
feet below the bottom of the site within 100 years. Therefore, utilizing the known data in a
conservative fashion, impacts to groundwater from the landfills are unlikely. However,
modeling suggested that groundwater will be impacted by vadose zone contamination at Sites
FT-19candOT-51.
Human health and ecological risk assessments were performed for the COPCs at each site as
appropriate. The risk assessment addressed public health impacts from ingestion, inhalation, and
dermal exposure to the COPCs in the soil. Specific receptors and exposure scenarios were
identified for each site. The exposure scenarios used to evaluate the potential risk for a particular
site were dependent on the proposed reuse of land parcel in which a site was located, the COPCs
identified at the site, and the potential completed exposure pathways. At the time of the remedial
investigation and performance of the risk assessment, the proposed reuse of land parcels at
GAFB were identified in the base Management Action Plan (MAP) (USAF, 1993). Exposure
scenarios that were used for each site-specific risk assessment included: industrial/commercial,
trespasser/visitor, construction worker (potential surface soil exposure), construction worker
(potential subsurface soil exposure), and future resident. Additional details describing the risk
assessment methodology are presented in the OU 3 RI Report (Montgomery Watson, 1996a).
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Based on the results of the RI activities and results of the risk assessment, sites that posed a
potential threat to human health and the environment were analyzed in detail in the OU 3 FS.
The sites assessed in the OU 3 FS Report were grouped in "landfill sites" and "TPH/VOC sites"
because of the similarity between the sites in each group with respect to contaminant type,
distribution, site characteristics, and potential cleanup activities. The "landfill sites" included:
Sites DP-03, DP-04. LF-12, LF-14, LF-44, and the SEDA (remediation boundary includes nine
sites; see Table 1). The "TPH/VOC sites" included: WP-17, FT-19a, FT-19b, FT-19c, FT-20
(soil), OT-51, SS-59, and OT-69. A separate detailed FS analysis of Site OT-69 was presented in
the RI/FS for the TCE/tetrachloroethene (PCE) Study Area (IT, 1995a).
Table 1 summarizes the 60 OU 3 IRP sites and the proposed remedy (i.e., NFA or the remedial
alternative selected through the FS process). The findings and conclusions of this ROD are
based on the analysis of OU 3 presented in the final FS Report (Montgomery Watson, 1997a)
and the accompanying Proposed Plan (Montgomery Watson, 1997b). The technical information
supporting each alternative is included in these reports and the OU 3 RI Report (Montgomery
Watson, 1996a).
23 HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Community Relations Plan (CRP) was completed in 1991 for GAFB by IT following
USEPA guidance (IT, 1991). Consistent with the CRP, the USAF established a Technical
Review Committee (TRQ which was composed of the USEPA, DTSC, Lahontan RWQCB, and
representatives from adjacent communities. The TRC met on a quarterly basis to provide
community representatives with up-to-date information on recent milestone events. In January
1994, GAFB established the Restoration Advisory Board (RAB) which replaced the TRC. The
RAB met on a quarterly basis until 1997 when it voted to move to an annual meeting. The
meetings are open to the public. The RAB is designed to act as a focal point for environmental
exchange between GAFB and the public.
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The OU 3 RI Report (Montgomery Watson, 1996a), OU 3 FS Report (Montgomery Watson,
1997a), and OU 3 Proposed Plan (Montgomery Watson, 1997b) were released to the public and
were made available in both the Administrative Record File and in information repositories
maintained at the following locations:
• The Air Force Base Conversion Agency (AFBCA) Office at GAFB
The Victorville Branch of the San Bernardino County Library
• The Adelanto Branch of the San Bernardino County Library
The availability of these documents and announcement of the public meeting and public
comment period were published in the Daily Press in Victorville, the Desert Dispatch in
Barstow, and the Sun in San Bernardino in September 1997. A press release was sent to five
other local newspaper and radio organizations announcing the public meeting and public
comment period.
The Proposed Plan was mailed in September 1997 to all parties identified in the CRP, including
government officials, media, private organizations, and interested members of the community.
A public comment period was held from September 22, 1997 to October 22, 1997. A public
meeting was held on October 8, 1997 at the Green Tree Inn, Victorville, California.
Representatives from the USAF, USEPA, DTSC, and Lahontan RWQCB were present at the
meeting. The Responsiveness Summary (Section 3.0 of this ROD) contains responses to
questions from the meeting and comments submitted by mail.
2A SCOPE AND ROLE OF OPERABLE UNIT WITHIN THE SITE
STRATEGY
As summarized in Section 2.1, the suspected hazardous waste sites present at GAFB were
grouped into three OUs based on the type of waste present and the geographical location (Figure
2). This ROD deals specifically with OU 3. Chemicals found at 60 OU 3 ERP sites potentially
relate to activities associated with equipment maintenance; fire training; fuel use and storage;
pest control; laboratory, shop, and hospital operations; and landfill and solid waste disposal.
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As summarized in Table 1,40 OU 3 sites were recommended for NFA based on the results of the
WPA (JMM, 1992) and the OU 3 RI investigation (Montgomery Watson, 1996a). Land use
restrictions were recommended for Site LF-35 in the OU 3 WPA (JMM, 1992). Final decisions
regarding the groundwater in the vicinity of Site FT-20 will be determined in the OU 2 ROD
because it is currently associated with the groundwater contamination at OU 2 (this affected
groundwater is now referred to as FT-20 [groundwater]). The remaining role for OU 3 is to set
forth the remedial action to be conducted to remediate the remaining sites that were presented in
the OU 3 FS Report (Montgomery Watson, 1997a). These remaining sites (Figure 6) are
presented in two groups: the landfill sites (DP-03, DP-04, LF-12, LF-14, LF-44, and the SEDA
[remediation boundary includes nine sites]); and the TPH/VOC sites (WP-17, FT-19a, FT-19b,
FT-19c, FT-20 [soil], OT-51, SS-59, and OT-69) and are discussed in detail below.
2JB LANDFILL SITE SUMMARY
This section summarizes the site characteristics, risk assessment results, descriptions of the
alternatives evaluated, alternatives comparison, and the selection of the final remedies for the OU
3 landfill sites requiring action (Sites DP-03, DP-04, LF-12, LF-14, LF-35, LF-44, and the
SEDA).
Site characterization activities were not performed for Site LF-35 as part of the OU 3
investigations. Site LF-35 is a reported landfill for asbestos and fiberglass located in Parcel A.
These constituents are not expected to be mobile in soils. Unless mobilized via excavation
activities, any asbestos or fiber glass present should not pose a threat to human health or the
environment. Therefore, land use restrictions are recommended in the OU 3 WPA (JMM, 1992).
By placing land use and deed restrictions on the site forbidding disturbance of buried materials,
the potential exposure pathways for asbestos or fiberglass .will not be completed and protection
of human health would be assured.
The site characterization activities for the remaining landfill sites arc discussed below.
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2.5.1 Summary of Landfill Site Characteristics and Risk Assessments
The OU 3 landfill sites presented in this ROD were investigated and evaluated using the same
rationale and investigative techniques, including geophysics, soil gas, test pits, and soil and
groundwater sampling. Table 2 presents a summary of the OU 3 landfill site characterizations on
a site-specific basis. The results of the each of the landfill site investigations were similar;
various inorganics were detected as were hydrocarbons, semi volatile organic compounds
(SVOCs), and dioxins. The results of the baseline risk assessments indicated that although there
were some sites with a maximum excess iifetime cancer risk above the California benchmark of
1E-06, all were within or below the USEPA guidelines of 1E-04 to 1E-06. The site-specific
ecological risk assessments indicated that a potential risk to ecological receptors was present at
Sites DP-03, DP-04, LF-12, LF-14, and the SEDA. Ecological risks were considered
insignificant at Site LF-44.
The site characterizations and risk assessments for the landfill sites requiring remedial action are
summarized below. Additional details regarding the site characterizations and risk assessments
are presented in the OU 3 RI/FS reports (Montgomery Watson, 1996a and 1997a).
2.5.1.1 Site DP-03. Site DP-03 is a suspected acid and oil burial site located
approximately 400 feet north of the northeast end of the Crosswind/Secondary Runway. The
following subsections summarize the site characterization and risk assessment for Site DP-03.
Site Characterization. To characterize Site DP-03, aerial GPR and surface geophysics
including GPR, electromagnetic terrain conductivity (EM), and magnetometry (MAG) were
performed. Additionally, an extensive soil-gas program was conducted, surface and subsurface
(test pit) samples were collected and analyzed, and physical site conditions were evaluated. Data
gathered were used to perform fate and transport modeling and were also incorporated into the
baseline risk assessment.
Geophysical anomalies suggested the presence of buried material concentrated near the center of
the site. VOCs in shallow soil-gas were detected sporadically throughout the site. Three test pits
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were excavated to depths up to 10 feet to investigate geophysical and soil-gas anomalies. In
general, geophysical anomalies corresponded to construction debris such as rebar, concrete, and
asphalt, and fill materials were encountered to depths greater than 9 feet bgs. No evidence of
buried drums were found, and no soil staining or visual indications of contamination was noted
in the test pits. Lead, 10 SVOCs, and hydrocarbons were detected sporadically in surface and
subsurface samples above background. Although benzene, toluene, ethylbenzene, and xylene
(BTEX) was detected in the soil gas, no VOC contamination was found in the surface or
subsurface soil samples. Vadose zone modeling results showed that even under the most
conservative conditions, the most mobile constituent detected at any OU 3 landfill site will not
migrate deeper than 20 feet below the bottom of the disturbed areas within 100 years. Therefore,
the less mobile contaminants detected at this site would not be expected to migrate deeper than
20 feet below the bottom of the disturbed areas. Because the depth to groundwater beneath Site
DP-03 is greater than 100 feet, modeling results indicate that there is no potential for
contaminant leaching to groundwater.
Risk Assessment. As described in Section 2.2.2, a baseline risk assessment was performed for
Site DP-03 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). Using the likely future land use of an
airfield and related facilities, the baseline human health risk assessment evaluated risk for the
following scenarios: industrial/commercial, trespasser/visitor, construction worker (potential
surface soil exposure), and construction worker (potential subsurface soil exposure). This
baseline risk assessment estimated the highest excess lifetime cancer risk of 1.9E-05, primarily
because of polynuclear aromatic hydrocarbons (PAHs) under an industrial/commercial scenario.
The qualitative ecological benchmark screening indicated that there are potential risks to
ecological receptors because of the localized presence of PAHs. However, the results of
subsequent quantitative food chain modeling specifically for bioaccumulative compounds
indicated that bioaccumulative compounds of potential ecological concern (COPECs) pose no
significant risks to vegetation and wildlife at the site. Human activities associated with the
proposed land use for this parcel are expected to limit the selection of Site DP-03 as a primary
habitat for many ecological receptors.
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2.5.1.2 Site DP-04. Site DP-04 is a reported pesticide and oil drum burial site located
between Sites DP-03 and LF-14. The following subsections summarize the site characterization
and risk assessment for Site DP-04.
Site Characterization. To characterize Site DP-04, aerial GPR and surface geophysics
including GPR, EM, and MAG were performed. Additionally, an extensive soil-gas program
was conducted, surface and subsurface (test pit) samples were collected and analyzed, and
physical site conditions were evaluated. Data gathered were used to perform fate and transport
modeling and were also incorporated into the baseline risk assessment.
Geophysical anomalies suggested the presence of buried material concentrated near the center of
the site. VOCs in shallow soil-gas were detected sporadically throughout the site. Six test pits
were excavated to depths up to 15 feet to investigate geophysical and soil-gas anomalies. In
genera], geophysical anomalies corresponded to construction debris such as concrete, metal,
wood, and plastic, and fill materials we.re encountered to depths greater than 15 feet bgs. No
evidence of buried drums were found, and no soil staining or visual indications of contamination
were noted in the test pits. Lead, nickel, mercury, zinc, two pesticides, one polychlorinated
biphenyl (PCB) and hydrocarbons were detected sporadically in surface and subsurface samples
above background. Although benzene and total BTEX were detected in the soil gas, no VOC
contamination was found in the surface or subsurface soil samples. Vadose zone modeling
results showed that even under the most conservative conditions, the most mobile constituent
detected at any OU 3 landfill site will not migrate deeper than 20 feet below the bottom of the
disturbed areas within 100 years. Therefore, the less mobile contaminants detected at this site
would not be expected to migrate deeper than 20 feet below the bottom of the disturbed areas.
Because the depth to groundwater beneath Site DP-04 is greater than 100 feet, modeling results
indicate that there is no potential for contaminant leaching to groundwater.
Risk Assessment. As described in Section 2.2.2, a baseline risk assessment was performed for
Site DP-04 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this site
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included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), and construction worker (potential subsurface soil exposure). This baseline human
health risk assessment estimated the highest excess lifetime cancer risk of 6.7E-05, primarily
because of Aroclor 1260 (a PCB) under the industrial/commercial scenario.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., barn owl), primarily because of the highly localized presence of Aroclor
1260. However, human activities associated with the proposed land use for this parcel along
with the disturbed nature of the site are expected to limit the selection of Site DP-04 as a primary
habitat for many ecological receptors.
3 Site LF-12. Site LF-12 is an abandoned landfill site located in an unpaved,
relatively undeveloped area north of the base residential area and east of Phantom Street. The
following subsections summarize the site characterization and risk assessment for Site LF-12.
Site Characterization. To characterize Site LF-12, aerial GPR and surface geophysics
including GPR, EM, and MAG were performed. Additionally, an extensive soil-gas program
was conducted, surface and subsurface (test pit) samples were collected and analyzed, up- and
downgradient monitoring wells were installed and sampled, and physical site conditions were
evaluated. Data gathered were used to perform fate and transport modeling and were also
incorporated into the baseline risk assessment.
*
Geophysical anomalies suggested the presence of buried material concentrated near the center of
the site. VOCs in shallow soil gas were detected sporadically throughout the site. Five test pits
were excavated to depths up to 15 feet to investigate geophysical and soil-gas anomalies. In
general, geophysical anomalies corresponded to construction debris such as metal, plastic,
concrete, glass and plaster board, and fill materials were encountered to depths greater than 10
feet bgs. No evidence of buried drums were found, and no soil staining or visual indications of
contamination was noted in the test pits. Barium, lead, mercury, zinc, three dioxins, and
hydrocarbons were detected sporadically in surface and subsurface samples above background.
Although benzene, total BTEX, and TCE were detected in the soil gas, no VOC contamination
•
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was found in the surface or subsurface soil samples. One monitoring well was installed
upgradient of the site, and three monitoring wells were installed downgradient of the site.
Analysis of the soil samples collected from the borings and the groundwater samples collected
from the wells indicate that no leaching of contaminants has occurred at the site. Vadose zone
modeling results showed that even under the most conservative conditions, the most mobile
constituent detected at any OU 3 landfill site will not migrate deeper than 20 feet below the
bottom of the disturbed areas within 100 years. Therefore, the less mobile contaminants detected
at this site would not be expected to migrate deeper than 20 feet below the bottom of the
disturbed areas. Because the depth to groundwater beneath Site LF-12 is greater than 100 feet,
modeling results indicate that there is no potential for contaminant leaching to groundwater.
Risk Assessment As described in Section 2.2.2, a baseline risk assessment was performed for
Site LF-12 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this site
included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), construction worker (potential subsurface soil exposure), and future resident. This
baseline human health risk assessment estimated the highest excess lifetime cancer risk of 7.7E-
07, primarily because of dioxins under the future resident scenario. This is below the benchmark
values for risk assessment.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., barn owl), primarily because of the highly localized presence of dioxins,
lead, zinc, and barium. However, human activities associated with the proposed land use for this
parcel are expected to limit the selection of Site LF-12 as a primary habitat for many ecological
receptors.
Although the calculated risk to human health was below the benchmark, because the site was an
abandoned landfill and there is a potential risk to ecological receptors, closure actions were
considered in the OU 3 FS.
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25.1.4 Site LF-14. Site LF-14 is an abandoned landfill site located in an unpaved,
relatively undeveloped area east of the Alert Hangar. The following subsections summarize the
site characterization and risk assessment for Site LF-14.
Site Characterization. To characterize Site LF-14, aerial GPR, and surface geophysics
including GPR, EM, and MAG were performed. Additionally, an extensive soil-gas program
was conducted, surface and subsurface (test pit) samples were collected and analyzed, up- and
downgradient monitoring wells were installed and sampled, and physical site conditions were
evaluated. Data gathered were used to perform fate and transport modeling and were also
incorporated into the baseline risk assessment.
Geophysical anomalies suggested the presence of buried materials at the site. VOCs in shallow
soil-gas were detected sporadically throughout the site. Seven test pits were excavated to depths
up to 15 feet to investigate geophysical and soil-gas anomalies. In general, geophysical
anomalies corresponding to construction debris such as metal, wood, glass, plastic, asphalt,
concrete, gravel, trash, and fill materials were encountered to depths greater than 15 feet bgs.
Two of the test pits were located near crushed drums on the surface of the site. Empty and
crushed drums were also located in these test pits, but no evidence of soil staining was noted on
the surface of the site or in the test pits. Lead, cadmium, copper, mercury, manganese, zinc, four
SVOCs, three pesticides, toluene, and hydrocarbons were detected sporadically in surface and
subsurface samples above background. Although benzene, toluene, PCE, TCE, trichloroethane
(TCA), freon-11 (F-ll), and total BTEX were detected in the soil gas, no widespread VOC
contamination was found in the surface or subsurface soil samples. Toluene was the only VOC
detected at the site, and it was detected in two of the subsurface samples. Two monitoring wells
were installed downgradient of the site to assess the water quality. Analysis of the soil samples
collected from one boring and the groundwater samples collected from the wells indicate that no
leaching of contaminants has occurred at the site. Vadose zone modeling results showed that
even under the most conservative conditions, the most mobile constituent detected at any OU 3
landfill site will not migrate deeper than 20 feet below the bottom of the disturbed areas within
100 years. Therefore, the less mobile contaminants detected at this site would not be expected to
migrate deeper than 20 feet below the bottom of the disturbed areas. Because the depth to
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groundwater beneath Site LF-14 is greater than 100 feet, modeling results indicate that there is
no potential for contaminant leaching to groundwater.
Risk Assessment As described in Section 2.2.2, a baseline risk assessment was performed for
Site LF-14 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this site
included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), and construction worker (potential subsurface soil exposure). This baseline human
health risk assessment estimated the highest excess lifetime cancer risk of l.OE-05 primarily
because of cadmium under an industrial/commercial scenario. Although this is above the
benchmark values for risk assessment, the cadmium at the site is considered naturally occurring
and within background ranges.
The results of the ecological risk assessment indicate a potential risk to burrowing mammals and
their predators (e.g., bam owl), because of the localized presence of cadmium, lead, and
pesticides. However, human activities associated with the proposed land use for this parcel are
expected to limit the selection of Site LF-14 as a primary habitat for many ecological receptors.
Although the calculated risk to human health was due to constituents that are considered
naturally occurring, because the site was an abandoned landfill and there was a potential risk to
ecological receptors, closure actions were considered in the OU 3 FS.
2^.1.5 Site LF-44. Site LF-44 is an abandoned landfill site located about 1.000 feet
south of Site LF-14. The following subsections summarize the site characterization and risk
assessment for Site LF-44.
Site Characterization. To characterize Site LF-44 aerial GPR and surface geophysics including
GPR, EM, and MAG were performed. Surface and subsurface (test pit) samples were collected
and analyzed, and physical site conditions were evaluated. Data gathered were used to perform
the fate and transport modeling and were also incorporated into the baseline risk assessment.
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Geophysical anomalies suggested the presence of buried material concentrated near the center of
the site. VOCs in shallow soil gas were detected sporadically throughout the site. Four test pits
were excavated to depths up to 15 feet to investigate geophysical and soil-gas anomalies. In
general, geophysical anomalies corresponded to construction debris such as concrete and trash,
and fill materials were encountered to depths greater than 8 feet bgs. No evidence of buried
drums were found, and no soil staining or visual indications of contamination was noted in the
test pits. Antimony, lead, and hydrocarbons were detected sporadically in surface and subsurface
samples above background. No VOC contamination was found in the surface or subsurface soil
samples. Vadose zone modeling results showed that even under the most conservative
conditions, the most mobile constituent detected at any OU 3 landfill site will not migrate deeper
than 20 feet below the bottom of the disturbed areas within 100 years. Therefore, the less mobile
contaminants detected at this site would not be expected to migrate deeper than 20 feet below the
bottom of the disturbed areas. Because the depth to groundwater beneath Site LF-44 is greater
than 100 feet, modeling results indicate that there is no potential for contaminant leaching to
groundwater.
Risk Assessment As part of the screening for the baseline human health risk assessment, no
COPCs were identified, therefore, no human health risk assessment was completed.
The results of the ecological risk assessment suggest some potential ecological impacts at Site
LF-44 from physical disturbances. Some stress on vegetation exists at the site as a result of
physical disturbance related to former site activities. However, significant chemical risks to
vegetation or wildlife were not indicated by the site characterization data. Nevertheless, because
this site was an abandoned landfill with exposed debris, in order to restore the natural surface at
the site, closure actions were considered in the OU 3 FS.
2*5.1.6 Site SEDA. The geographic area known as the SEDA historically included 10
OU 3 sites: five landfill sites (Sites LF-07, LF-08, RW-09, DP-10, and LF-11), one burial site
(WP-40), one spill site (SS-52), and three munitions disposal areas (DP-15, DP-33, and DP-34).
The location of the SEDA relative to GAFB is presented in Figure 2. Site LF-11 is located
generally to the east of the other sites and was recommended for NFA in the OU 3 WPA (JMM,
*
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1992). Because of the geographical proximity of the remaining nine sites and the generally
indeterminable boundaries between them, the entire area has been handled as a unit. The
following subsections summarize the SEDA site characterization and risk assessment.
Site Characterization. To characterize the SEDA, aerial GPR and surface geophysics including
GPR, EM, and MAG were performed. Additionally, an extensive soil-gas program was
conducted, surface and subsurface (test pit and soil borings) samples were collected and
analyzed, up- and downgradient monitoring wells were installed and sampled, and physical site
conditions were evaluated. Data gathered were used to perform fate and transport modeling
using SESOIL and were also incorporated into the baseline risk assessment.
Geophysical anomalies suggested the presence of buried materials at the site. VOCs in shallow
soil-gas were detected sporadically throughout the site. Twenty-two test pits were excavated to
depths up to 15 feet to investigate geophysical and soil-gas anomalies. In general, geophysical
anomalies corresponded to construction debris such as concrete, asphalt, metal, paper, glass,
wood, rubber, and plaster board. This construction debris, burned debris, and fill material was
encountered to depths greater than 13.5 feet bgs. A few crushed and empty drums were noted as
surface debris at the site; however, no evidence of buried drums was found and no soil staining
or visual indications of contamination was noted in the test pits. Although total benzene, BTEX,
PCE, TCE, dichloroethene (DCE), TCA, Freon-11 (F-l 1), and carbon tetrachloride were detected
in the soil gas, no widespread VOC contamination was found in the surface or subsurface soil
samples. Toluene was the only VOC detected at the site, and it was detected in two subsurface
samples. Two monitoring wells were installed upgradient of the site, and seven monitoring wells
were installed downgradient of the site. Analysis of the soil samples collected from the borings
and the groundwater samples collected from the wells indicates that no leaching of contaminants
has occurred at the site. Vadose zone modeling results (SESOIL) showed that even under the
most conservative conditions, the most mobile constituent detected at any OU 3 landfill site will
not migrate deeper than 20 feet below the bottom of the disturbed areas within 100 years.
Therefore, the less mobile contaminants detected at this site would not be expected to migrate
deeper than 20 feet below the bottom of the disturbed areas. Because the depth to groundwater
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beneath the SEDA is greater than 100 feet, modeling results indicate that there is no potential for
contaminant leaching to groundwater.
Risk Assessment. As described in Section 2.2.2, a baseline risk assessment was performed for
the SEDA for which risk assessment scenarios were evaluated based on the proposed reuse of the
land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this site
included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), construction worker (potential subsurface soil exposure), and future resident. This
baseline human health risk assessment estimated the highest excess lifetime cancer risk of 8.4E-
05 primarily because of arsenic and chromium under the future resident scenario. Although this
is above the benchmark values for risk assessment, the arsenic and chromium values detected at
the SEDA are considered within background and naturally occurring.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., barn owl), because of the localized presence of several metals and
dioxin/furan congeners.
Although the calculated risk to human health was due to constituents that are considered
naturally occurring, because the site was an abandoned landfill and there is a potential risk to
ecological receptors, closure actions were considered in the OU 3 FS.
2.5.2 Description of Landfill Site Alternatives
Based on the results of remedial investigations, it was determined that remedial action was
potentially necessary at the OU 3 landfill sites (DP-03, DP-04, LF-12, LF-14, LF-44, and the
SEDA). An FS analysis was performed in which (1) remedial action objectives (RAOs) were
identified; (2) potentially applicable technologies were . identified and screened based on
effectiveness, implementability, and cost; (3) the technologies retained after the initial screening
were combined into potential alternatives for each site; and (4) the alternatives were then
subjected to a detailed analysis with respect to the nine criteria defined by the USEPA for
CERCLA sites (USEPA. 1988).
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Alternatives were developed and evaluated for the landfill sites as a group because of the
similarity between the sites with respect to contaminant type, distribution, site characteristics,
and potential actions. The RAOs established for the OU 3 landfill sites are summarized below:
• prevent direct contact with landfill contents;
• minimize infiltration that may result in waste constituents leaching to
groundwater;
• control surface water runoff and run-on, and erosion; and
• monitor groundwater quality to determine if landfill contaminants are leaching to
the groundwater.
Five remedial alternatives were developed for the OU 3 landfill sites from an analysis of
remedial technologies as part of the OU 3 FS (Montgomery Watson, 1997a). The five
alternatives, with their components, are as follows:
Alternative 1 (No Action with Monitoring)
1) Groundwater Monitoring
2) 5-Year Site Review
Alternative 2 (Institutional Controls)
1) Surface Restoration
2) Access Restrictions
3) Land Use Restrictions
4) Groundwater Monitoring
5) 5-Year Site Review
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)
1) Surface Controls
2) Surface Restoration
3) Access Restrictions
4) Land Use Restrictions
5) Groundwater Monitoring
6) 5-Year Site Review
Alternative 4 (Soil Cover)
1) Native Soil Cover
2) Surface Controls
3) Surface Restoration
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4) Access Restrictions
5) Land Use Restrictions
6) Groundwater Monitoring
7) 5-Year Site Review
Alternative 5 (Synthetic Cap)
1) Synthetic Cap
2) Native Soil Cover
3) Surface Controls
4) Surface Restoration
5) Access Restrictions
6) Land Use Restrictions
7) Groundwater Monitoring
8) 5-Year Site Review
These alternatives are presented in detail in the OU 3 FS and are summarized in the sections
below.
2.5.2.1 Alternative 1: No Action with Monitoring. As required by the NCP, the no
action alternative serves as a baseline against which other landfill site alternatives are compared.
Its components include groundwater monitoring and the 5-year site review.
Groundwater monitoring at the OU 3 landfill sites would be part of the an approved basewide
long-term monitoring plan for GAFB. Selected monitoring wells at each site would be sampled
annually, semi-annually, or quarterly, to determine if landfill contaminants are leaching to the
groundwater.
The no action alternative would leave the landfill contents in place with no closure activities
undertaken. Because contaminants would remain on site, a site review would be conducted
every 5 years as required by CERCLA. This would include a review of annual environmental
monitoring results to determine if landfill contaminants have migrated to the environment (i.e.,
moved beyond the known boundaries of the landfill sites). The purpose of the 5-year site review
and long-term monitoring would be to assess the effectiveness of an alternative.
2.5.2.2 Alternative 2: Institutional Controls. Alternative 2 includes access and land
use restrictions, surface restoration, groundwater monitoring, and the 5-year site review.
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Access restrictions would involve the installation of 8-foot-high chain-link fences with barbed
wire and/or posting of warning signs posted along the perimeter of the site. The locations of the
fences at each landfill would be determined as part of the design and would minimize access to
people, vehicular traffic, and terrestrial animals.
The implementation of land use restrictions at the OU 3 landfill sites would assure the
protectiveness of the remedy and human health. Deed restrictions would be recorded to restrict
use of the sites for the following purposes: 1) a residence, including any mobile home or factory-
built housing, constructed or installed for use as permanently occupied residential human
habitation, 2) a long-term care hospital for humans, 3) a traditional public or private school for
persons under 21 years of age, and 4) a day care center. In addition, the deed would prohibit the
disturbance of the landfill cover, subsurface soils, and fencing without prior approval from the
USAF and appropriate state and local agencies.
Surface restoration would involve the removal of municipal wastes and debris, such as plastics,
tires, paper products, rubble, etc., from the landfill surface. Use of backhoes and dump trucks to
remove wastes would be combined with manual collection, following the proper health and
safety procedures. Collected wastes would be disposed of at an off-site Class m landfill facility,
or may be consolidated with other wastes under an OU 3 landfill cap.
The definitions of the other components of this alternative (e.g., groundwater monitoring and the
5-year site review) are the same as for Alternative 1.
£5.2.3 Alternative 3: Surface Controls/Existing Cover Rehabilitation. Alternative 3
has the same components as Alternative 2 with the addition of surface controls. In addition, the
existing cover conditions would be evaluated and rehabilitated to functional parameters as
discussed below.
Surface controls include general site grading, drainage, and revegetation. General site grading
would be accomplished by using cut-and-fill techniques which involve excavation of clean soils
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from outside the landfill boundary and from elevated mounds of clean soils within the landfill
and consolidation of these soils in the "potholes" within the landfill. In order to minimize
intrusive activities at the OU 3 landfill sites, the remedial design for this alternative would ensure
that the fill volume is greater than the cut volume and the difference would be imported from and
off-site borrow source. This design would effectively produce a soil cover on the landfill with an
estimated thickness of 12 to 18 inches. The final grade for each site would have a minimum
slope of 1.5 percent, with the actual slope designed to fit the natural topography of the site. Site
drainage would be implemented by constructing drainage channels around the landfill boundary
to divert surface water away from the landfill site. A conceptual diagram of the implementation
of surface controls/existing cover rehabilitation is shown on Figure 7.
The land use restrictions for sites where surface controls would be implemented would include
the prohibition of subsurface development (e.g., excavation, pile-driving) and excessive
vehicular traffic (e.g., off-road vehicles, dirt bikes), in addition to the more general types of land
use restrictions which may be applied.
2.5.2.4 Alternative 4: Soil Cover. Alternative 4 has the same components as
Alternative 3 with the addition of a 24-inch-thick native soil cover installed over the graded
landfill surface. The soil cover would be compacted only for structural purposes because the
native soil at GAFB is expected to be difficult to compact to low permeability levels. The
primary purpose of the native soil cover is to provide a separation layer that would prevent direct
contact with landfill contents. A conceptual diagram of a native soil cover is shown on Figure 8.
Alternative 5: Synthetic Cap. Alternative 5 has the same components as
Alternative 4 with the addition of a synthetic flexible membrane liner (FML), 30-mil thick,
installed over the graded landfill surface. A native soil cover would then be installed over the
synthetic liner, as described for Alternative 4. In addition to preventing direct contact with
landfill contents, the synthetic cap also prevents surface water infiltration that could lead to the
leaching of landfill contaminants to the groundwater and/or storm water. A conceptual diagram
of a synthetic cap is shown on Figure 8.
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2.53 Summary of Comparative Analysis of Alternatives for the Landfill Sites
The remedial alternatives developed were analyzed in detail using the nine evaluation criteria
required by the NCP. These criteria are classified as threshold criteria, primary balancing
criteria, and modifying criteria. Threshold criteria are:
1) Overall protection of human health and the environment
2) Compliance with applicable or relevant and appropriate requirements (ARARs)
Primary balancing criteria are:
3) Long-term effectiveness and permanence
4) Reduction of TMV through treatment
5) Short-term effectiveness
6) Implementability
7) Cost
Modifying criteria are:
8) State/support agency acceptance
9) Community acceptance
The resulting strengths and weaknesses of the alternatives were then weighed to identify the
alternative providing the best balance among the nine criteria. Table 3 summarizes this
comparison.
&5.3.1 Overall Protection of Human Health and the Environment. This criterion is
an overall assessment of whether each alternative provides adequate protection of human health
and the environment. The evaluation focuses on a determination of the degree to which a
specific alternative achieves adequate protection and describes the manner in which site risks are
eliminated, reduced, or controlled through treatment, engineering, or institutional measures. The
potential for cross-media impacts is also assessed.
Alternative 1: Does not provide any direct protection of human health and the environment
because no landfill closure activities are undertaken. This alternative would not change the risks
currently associated with a site.
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Alternative 2: Provides the minimum requirements necessary to protect human health by
reducing the potential for direct contact with landfill contents through access and land use
restrictions and the removal of municipal wastes from the surface. However, Alternative 2 does
not satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion and
current risks associated with the site are only slightly reduced.
Alternative 3: Provides better protection of human health and the environment than Alternative
2 by providing a final cover with the proper grade and protected slopes. The potential for direct
contact with landfill contents is substantially reduced and the potential for contaminant leaching
is reduced. By eliminating potential exposure pathways to landfill contaminants, the initially
low risks associated with the site are additionally minimized.
Alternative 4: Provides better protection of human health and the environment than Alternative
3 by providing a thicker soil cover. The potential for direct contact with landfill contents is
practically eliminated and the potential for contaminant leaching is further reduced. Alternative
4 provides additional confidence that the risks associated with the site are minimized.
Alternative 5: Provides the same protection of human health and better protection of the
environment than Alternative 4 by providing a final cover that is more effective in reducing
infiltration. The potential for contaminant leaching is practically eliminated.
2.53.2 Compliance with ARARs. Pursuant to Section 121 (d) CERCLA, as amended,
the remedial actions must attain a degree of cleanup which assures protection of human health
and the environment. In addition CERCLA requires that remedial actions meet standards,
requirements, limitations, or criteria that are ARARs. ARARs are of three types: chemical-,
action-, and location-specific. The three types of ARARs are defined as follows:
• Chemical-Specific ARARs. Chemical-specific ARARs include those
environmental laws and regulations that regulate the release to the environment of
materials possessing certain chemical or physical characteristics or containing
specified chemical compounds. These requirements generally set health- or risk-
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based concentration limits or discharge limits for specific hazardous substances
(USEPA, 1989).
Location-Specific ARARs. As defined in the USEPA draft guidance (USEPA,
1988): "Location-specific ARARs are restrictions placed on the concentration of
hazardous substances or the conduct of activities solely because they are in
specific locations. Some examples of special locations include floodplains,
wetlands, historic places, and sensitive ecosystems or habitats."
Action-Specific ARARs. Action-specific ARARs are restrictions that define
acceptable treatment and disposal procedures for hazardous substances. These
ARARs generally set performance, design, or other similar action-specific
controls or restrictions on particular kinds of activities related to management of
hazardous substances or pollutants, such as Resource Conservation and Recovery
Act of 1976 (RCRA) regulations for waste treatment, storage, and disposal.
These requirements are triggered by the particular remedial activities that are
selected to accomplish a remedy. The type and nature of these requirements is
dependent upon the particular remedial or removal action taken at a site.
Therefore, different actions or technologies are often subject to different action-
specific ARARs.
Identification and consideration of potential ARARs associated with a site and its remedial action
is an ongoing process throughout site characterization and remediation.
An ARAR may be either "applicable" or "relevant and appropriate," but not both. The NCP
(contained in Title 40 of the CFR Part 300) defines "applicable" and "relevant and appropriate
requirements" as follows:
"Applicable requirements means those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under federal environmental
or state environmental or facility siting law that specifically address a hazardous
substance, pollutant, contaminant, remedial action, location, or other circumstance at a
CERCLA site. Only those state standards that are identified by a state in a timely manner
and that are more stringent than federal requirements may be applicable."
"Relevant and appropriate requirements means those cleanup standards, standards of
control, and other substantive requirements, criteria, or limitations promulgated under
federal environmental or state environmental or facility siting laws that, while not
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'applicable' to a hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance at a CERCLA site, address problems or situations sufficiently
similar to those encountered at the CERCLA site that their use is well suited to the
particular site. Only those state standards that are identified by a state in a timely manner
and that are more stringent than federal requirements may be applicable."
In other words, a requirement is "applicable" when the remedial action or the circumstances at
the site satisfy all of the jurisdictional prerequisites of that requirement. Relevant and
appropriate requirements must be complied with to the same degree as if they were applicable,
but there is more discretion in this determination and it is possible for only part of a requirement
to be considered relevant and appropriate in a given case.
•
Where no promulgated standards exist for a given chemical or situation, nonpromulgated
advisories and guidance ("to-be-considered" [TBC] materials) issued by federal or state
government may be used in determining the necessary level of cleanup for protection of human
health or the environment. TBCs do not have the status of potential ARARs; however, in many
circumstances they will be considered along with ARARs as part of the site risk assessment and
may be used in determining the necessary level of cleanup.
Identification of ARARs and TBCs must be done on a site-specific basis. Neither CERCLA nor
the NCP provides across-the-board standards for determining whether a particular remedy will
effect an adequate cleanup at a particular site. Rather, the process recognizes that each site will
have unique characteristics that must be evaluated and compared to those'requirements that apply
under the given circumstances.
Final ARARs for the OU 3 landfill sites were established through discussions between the
Lahontan RWQCB, DTSC, USEPA, and USAF. A listing of agreed upon federal and state laws
and regulations that are ARARs for the OU 3 landfill sites is provided in Table 4. Based on the
ARARs identified: Alternative 1 will not comply with all ARARs for the landfill sites;
Alternative 2 may not comply with all federal and state ARARs on landfill closure at all sites;
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and Alternatives 3. 4, and 5 are expected to comply with the pertinent federal and state ARARs
on landfill closure such as grading, drainage, slope protection through revegetation, etc.
2.5.3.3 Long-Term Effectiveness and Permanence. The purpose of this criterion is to
assess the residual risk and the adequacy and reliability of controls associated with a particular
alternative. The magnitude of risk resulting from the presence of untreated waste or treatment
residuals is assessed with respect to the volume or concentration of residual contaminants.
The second component, adequacy and reliability of controls, assesses the containment systems
and institutional controls in place to determine if they are sufficient to ensure that both human
and environmental exposure is within protective levels. The long-term reliability of management
controls to provide continued protection from residuals is also addressed with regard to (1) the
potential need to replace technical components of the alternative, and (2) the potential exposure
pathway and resulting risks should the remedial action need replacement.
Alternative 1: This alternative does not satisfy the RAOs for preventing direct contact with
landfill contents, minimizing infiltration, and controlling runoff and soil erosion. Therefore, the
risks from direct contact and the potential for contaminant leaching remains unchanged.
Alternative 2: This alternative partially satisfies the RAO for preventing direct contact with
landfill contents (through surface restoration and access and land use restriction), thereby slightly
reducing the risks. However, the long-term reliability of access restrictions and surface
restoration would not be as reliable as the soil cover rehabilitation and/or installation described
for Alternatives 3 through 5. In addition, land use restrictions may be difficult to enforce in the
long term. Alternative 2 does not satisfy the RAOs for minimizing infiltration and controlling
runoff and soil erosion. Therefore, the potential for contaminant leaching remains unchanged.
Alternative 3: This alternative satisfies the RAO for preventing direct contact with landfill
contents (through surface controls and cover rehabilitation), thereby effectively minimizing
potential risks. The alternative effectively meets the RAOs for reducing infiltration and
controlling runoff and soil erosion, thereby reducing the potential for contaminant leaching.
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However, surface controls require comprehensive long-term maintenance to prolong their
effectiveness.
Alternative 4: This alternative effectively satisfies the RAOs for preventing direct contact with
landfill contents, minimizing infiltration, and controlling runoff and soil erosion, thereby
eliminating the risks and the potential for contaminant leaching. However, a soil cover requires
comprehensive long-term maintenance to prolong its effectiveness.
Alternative 5: This alternative effectively satisfies the RAOs for preventing direct contact with
landfill contents, minimizing infiltration, and controlling runoff and soil erosion, thereby
eliminating the risks and the potential for contaminant leaching. However, a soil cover and a
synthetic cap both require comprehensive long-term maintenance to prolong their effectiveness.
2.5.3.4 Reduction of Toxicity, Mobility, and Volume through Treatment.
Alternatives are assessed to determine the extent to which they permanently reduce TMV of the
contaminants posing the principal threats at a site. The specific factors considered in this
assessment include:
• treatment or recycling process(cs) of associated target contaminants and the
amount of contaminants to be destroyed or treated;
• degree of expected reduction in the TMV and the degree to which treatment or
recycling will be irreversible;
» type and quantity of treatment residuals expected to remain following treatment;
and
• whether or not the alternative satisfies the statutory preference for treatment as a
principal element.
Alternative 1: This alternative does not provide any reduction of TMV of contaminants in the
landfill sites.
Alternative 2: The removal of municipal wastes from the surface reduces the amount of wastes
at the landfill sites.
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Alternative 3: The removal of municipal wastes from the surface reduces the amount of wastes
at the landfill sites. This alternative does not provide any reduction of toxicity or volume of
contaminants in the landfill sites. However, the surface controls/existing cover rehabilitation
nummizes surface water infiltration and runoff, thereby reducing the mobility of contaminants
through leaching.
Alternative 4: The removal of municipal wastes from the surface reduces the amount of wastes
at the landfill sites. This alternative does not provide any reduction of toxicity or volume of
contaminants in the landfill sites. However, the surface controls, existing cover rehabilitation
and soil cover, minimize surface water infiltration and runoff, thereby reducing the mobility of
contaminants through leaching.
Alternative 5: The removal of municipal wastes from the surface reduces the amount of wastes
at the landfill sites. This alternative does not provide any reduction of toxicity or volume of
contaminants in the landfill sites. However, the surface controls, existing cover rehabilitation
so,l cover, and synthetic cap all minimize surface water infiltration and runoff, thereby reducing
the mobility of contaminants through leaching.
Short-Term Effectiveness. Alternatives are evaluated with respect to their
effects on human health and the environment during implementation of the remedial action. This
evaluation addresses protection of site workers and the community during remedial actions.
potential environmental impacts, and the time until remedial action objectives are achieved.
Alternative 1: This alternative results in no risks to construction workers because no closure
activities are undertaken.
Alternative 2: This alternative results in minimal risks to construction workers during surface
restoration activities.
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Alternative 3: This alternative results in minimal risks to construction workers during surface
restoration, surface controls, and existing cover rehabilitation activities.
Alternative 4: This alternative results in minimal risks to construction workers during surface
restoration, surface controls, existing cover rehabilitation, and soil cover installation activities.
Alternative 5: This alternative results in minimal risks to construction workers during surface
restoration, surface controls, existing cover rehabilitation, and soil cover and synthetic cap
installation activities.
2.5.3.6 Implementability. This criterion has three components: (1) technical feasibility,
(2) administrative feasibility, and (3) availability of services and materials. Each alternative is
assessed on the basis of factors within these three categories.
The assessment of the administrative feasibility of a particular remedial alternative is based on
the number and complexity of activities needed to coordinate with other offices and regulatory
agencies during preparation and implementation of the alternative. Factors that are considered in
the assessment of technical feasibility include:
• potential for problems associated with construction and operation of an
alternative;
• reliability of an alternative and its components;
• ease of undertaking additional remedial action, if needed; and
• ability to monitor the effectiveness of the remedy and evaluate the risks of
exposure should monitoring be insufficient to detect a failure.
The availability of services and materials is to be considered. This includes such items as off-site
treatment, storage or disposal capacity, equipment, and specialists.
The implementability of each remedy becomes progressively more difficult from Alternative 1 to
Alternative 5 because of the consecutive addition of components as described below.
-------
Alternative 1: This alternative is easily implemented because no closure activities are
undertaken. Groundwater monitoring is easy to implement and the materials required are readily
available. There arc no administrative difficulties associated with this alternative.
Alternative 2: Although more difficult to implement than Alternative 1, surface restoration is
easy to implement, using standard equipment and technologies and readily available services and
materials. Some administrative difficulties may be encountered for land use restrictions
depending on property disposal and reuse plans.
Alternative 3: This alternative is more difficult to implement than Alternative 2 with the
addition of surface controls and existing cover rehabilitation. Additional components are
feasible, using standard equipment and technologies and readily available services and materials.
Some difficulties in site grading may occur because of uneven topography in some areas. Some
administrative difficulties may be encountered for land use restrictions depending on property
disposal and reuse plans.
Alternative 4: This alternative is more difficult to implement than Alternative 3 with the
addition of the soil cover component. Additional components arc feasible, using standard
equipment and technologies and readily available services and materials. Some administrative
difficulties may be encountered for land use restrictions depending on property disposal and
reuse plans.
Alternative 5: This is the most difficult to implement with the addition of the synthetic cap
component. Implementation of the synthetic cap is feasible, using standard equipment and
technologies and readily available services and materials. Installation of the synthetic cap can be
difficult and care must be taken so that punctures or tears to not develop during placement.
Some administrative difficulties may be encountered for land use restrictions depending on
property disposal and reuse plans.
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2,53.7 Cost. Both capital costs and operation and maintenance costs are considered for
each alternative, with a target accuracy of -30 to +50 percent. Capital costs include both direct
(e.g., equipment) and indirect (e.g., contingency allowances) costs. Costs are presented on a
present-worth basis over a period of 30 years, with a discount rate of 7 percent. Table 5 presents
a summary of the remedial alternative costs for the landfill sites for each of the five alternatives.
Detailed cost analysis is presented in the OU 3 FS Report (Montgomery Watson, 1997a).
2.5.3.8 State Acceptance. This assessment considers the technical and administrative
issues and concerns the state or support agency may have regarding each of the alternatives.
Final application of this criterion will occur in the approval of this ROD.
Alternative 1: It is likely the state would not accept this alternative because it does not include
components to achieve the RAOs, in particular, it does not actively prevent contact with landfill
contents or minimize infiltration.
Alternative 2: It is unlikely the state would accept this alternative for sites with COPCs
resulting in calculated human health or COPECs resulting in calculated ecological risk because it
does not actively minimize infiltration. However, this site is likely to be satisfactory for sites
with exposed debris but not having COPCs or COPECs (i.e., Site LF-44).
Alternative 3: This alternative would be considered more acceptable than Alternatives 1 and 2
because it eliminates the potential for direct contact with landfill contents and reduces the
potential for contaminant leaching through the rehabilitated existing landfill cover with the use of
surface controls.
Alternative 4: This alternative may be perceived as preferable to Alternative 3 because of the
additional protection from contact with landfill contents and reduction of infiltration provided by
the native soil cover.
Alternative 5: This alternative may be perceived as preferable to Alternative 4 because of the
additional protection from infiltration provided by the synthetic liner.
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2.5.3.9 Community Acceptance. Community acceptance indicates the public support
for a given alternative. Section 3.0 of this ROD documents the community acceptance of the
selected remedies, as presented in the Proposed Plan (Montgomery Watson, 1997b). Section 3.0
includes a responsiveness summary that addresses the comments received during the public
comment period. The community did not express any significant objections to the selected
remedies during the public meeting or public comment period.
2.5.4 The Selected Remedies for the Landfill Sites
This section provides a description of the preferred alternatives for remediation of the OU 3
landfill sites based on the detailed evaluation of alternatives presented in the OU 3 FS Report
(Montgomery Watson, 1997a). This section includes the basis for selection of a preferred
alternative, a description of the preferred alternative, and cost analyses.
2^.4.1 Selection of the Preferred Alternatives. The RAOs established for the landfill
sites in the OU 3 FS are summarized in Section 2.5.2. An evaluation of the five alternatives with
respect to the nine CERCLA criteria resulted in the selection of the following preferred
alternatives to meet the RAOs for the OU 3 landfill sites.
Site DP-03. Under the industrial/commercial scenario, the baseline human health risk
assessment estimated the highest cancer risk of 1.9E-05 for this landfill site, primarily because of
the presence of PAHs. This risk value is above the California and USEPA acceptable benchmark
value of l.OE-06.
The ecological risk assessment indicated that there were potential risks to ecological receptors
because of the localized presence of PAHs. However, the results of subsequent quantitative food
chain modeling specifically for bioaccumulative compounds indicated that bioaccumulative
constituents pose no significant risks to vegetation and wildlife at the site. Human activities
associated with the proposed land use for this parcel are expected to limit the selection of Site
DP-03 as a primary habitat for many ecological receptors.
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Because the benchmark for human health risk is exceeded and to expedite reuse, the RAO for
preventing direct contact with landfill contents must be satisfied by recommending either
Alternative 4 or Alternative 5 for Site DP-03 in the OU 3 FS. Both of these alternatives also
satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion. Alternative
4 is less expensive but equally effective in satisfying the RAOs as Alternative 5. The
implementation of surface controls and the installation of a soil cover at Site DP-03 would
constitute landfill closure and therefore make the site a potential candidate for delisting in the
future.
Therefore, Alternative 4 was the selected remedy for Site DP-03. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
Site DP-04. Under the industrial/commercial scenario, the baseline human health risk
assessment estimated the highest cancer risk of 6.7E-05 for this landfill site, primarily because of
the presence of Aroclor-1260. This risk value is above the California and USEPA acceptable
benchmark value of l.OE-06.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., bam owl), primarily because of the highly localized presence of Aroclor
1260. However, human activities associated with the proposed land use for this parcel along
with the disturbed nature of the site are expected to limit the selection of Site DP-04 as a primary
habitat for many ecological receptors.
Because the benchmark for human health risk was exceeded and to expedite reuse, the RAO for
preventing direct contact with landfill contents must be satisfied by recommending either
Alternative 4 or Alternative 5 for Site DP-04 in the OU 3 FS. Both of these alternatives also
satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion. Alternative
4 is less expensive but equally effective in satisfying the RAOs as Alternative 5. Therefore,
Alternative 4 was the recommended selected remedy for Site DP-04 in the OU 3 FS. The
implementation of surface controls and the installation of a soil cover at Site DP-04 would
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constitute landfill closure and therefore make the site a potential candidate for delisting in the
future.
Therefore, Alternative 4 was the selected remedy for Site DP-04. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
Site LF-12. Under the future resident scenario, the baseline human health risk assessment
estimated the highest cancer risk of 7.7E-07 for this landfill site, primarily because of the
presence of dioxins found in some burn pits. This risk value is below the California and USEPA
benchmark value of acceptable risk (i.e., risks calculated below this value would not require
attention).
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., barn owl), primarily because of the highly localized presence of dioxins,
lead, zinc, and barium. However, human activities associated with the proposed land use for this
parcel are expected to limit the selection of Site LF-12 as a primary habitat for many ecological
receptors.
In order to satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion.
Alternative 3 was the recommended remedy for Site LF-12 in the OU 3 FS. Alternatives 1 and 2
are not capable of satisfying these RAOs. In addition, the implementation of surface controN
and cover rehabilitation at Site LF-12 would constitute landfill closure and therefore make the
site a potential candidate for delisting in the future.
Therefore, Alternative 3 was the selected remedy for Site LF-12. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
Site LF-14. Under the industrial/commercial scenario, the baseline human health risk
assessment estimated the highest cancer risk of l.OE-05 for this landfill site, primarily because of
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the presence of cadmium values that are considered naturally occurring. Therefore, the probable
health risks at Site LF-14 are expected to be lower, thereby reducing the importance of the RAO
for preventing direct contact with landfill contents.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., bam owl), because of the localized presence of cadmium, lead, and
pesticides. However, human activities associated with the proposed land use for this parcel are
expected to limit the selection of Site LF-14 as a primary habitat for many ecological receptors.
In order to satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion.
Alternative 3 was the recommended remedy for Site LF-14 in the OU 3 FS. Alternatives 1 and 2
are not capable of satisfying these RAOs. In addition, the implementation of surface controls
and cover rehabilitation at Site LF-14 would constitute landfill closure and therefore make the
site a potential candidate for delisting in the future.
Therefore, Alternative 3 was the selected remedy for Site LF-14. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
Site LF-44. The screening risk assessment identified no COPGs for this landfill site. Therefore.
there are no human health risks for direct contact with landfill contents and there is no potential
for contaminant leaching. This practically eliminates the need to satisfy any of the RAOs for
Site LF-44.
The results of the ecological risk assessment suggested some potential ecological impacts at Site
LF-44 from physical disturbances. Some stress on vegetation exists at the site as a result of
physical disturbance related to former site activities. However, significant chemical risks to
vegetation or wildlife were not indicated by the site characterization data.
However, in order to restore the natural surface of the site, Alternadve 2 was recommended for
Site LF-44 in the OU 3 FS. The implementation of surface restoration and institutional controls
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at Site LF-44 would constitute landfill closure and therefore make the site a potential candidate
for delisting in the future.
Therefore, Alternative 2 was the selected remedy for Site LF-44. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
SEDA. Under the future resident scenario, the baseline human health risk assessment estimated
the highest cancer risk of 8.4E-05 for this landfill site, primarily because of arsenic and
chromium values that are considered naturally occurring. Therefore, the probable health risks at
the SEDA arc expected to be lower, thereby reducing the importance of the RAO for preventing
direct contact with landfill contents.
The results of the ecological risk assessment indicated a potential risk to burrowing mammals
and their predators (e.g., bam owl), because of the localized presence of several metals and
dioxin/furan congeners.
In order to satisfy the RAOs for minimizing infiltration and controlling runoff and soil erosion,
Alternative 3 was selected for the SEDA in the OU 3 FS. Alternatives 1 and 2 are not capable of
satisfying these RAOs. In addition, the implementation of surface controls and cover
rehabilitation at the SEDA would effectively produce a soil cover on the landfill with an average
thickness of 1.6 feet based on preliminary grading plans. Therefore, Alternative 3 would
constitute landfill closure and make the site a potential candidate for delisting in the future.
Therefore, Alternative 3 was the selected remedy for the SEDA. This alternative was
implemented as described in Section 2.9. Actions at the OU 3 landfill sites were completed in
April 1997.
2.5.4.2 Detailed Description of the Landfill Site Preferred Alternatives. The selected
alternatives from the OU 3 FS for the landfill sites (identified in Section 2.5.4.1) are described in
detail below.
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Sites DP-03 and DP-04. Installation of Alternative 4 for Sites DP-03 and DP-04 includes the
following specific activities:
• grading the existing soil cover to promote surface runoff and decrease infiltration
of surface water into landfill wastes;
• restoration of existing soil cover;
* installation of drainage ditches to prevent surface water from running onto the
sites;
* installation of a 2-foot-thick native soil cover to reduce the potential of exposure
to contaminants;
• re-establishment of native plant species on the graded surface;
0 implementation of long-term groundwater monitoring in accordance with an
approved basewide long-term groundwater monitoring plan;
0 installation and maintenance of site perimeter fencing to control site access
including signage warning against unauthorized vehicular traffic;
0 implementation of land use restrictions such as preventing construction activities
that would impair the integrity of the existing cover and preventing installation of
monitoring or injection wells in the site area (except where required for
environmental purposes); and
• 5-year site review to assess the effectiveness of the remedy.
Sites LF-12, LF-14, and the SEDA. Installation of Alternative 3 for Sites LF-12 and LF-14
includes the following specific activities:
• removal of surface debris; '
• grading or cutting of the surface to promote surface runoff and decrease
infiltration of surface water into landfill wastes;
• restoration of existing soil cover,
• installation of drainage ditches to prevent surface water from running onto the
sites;
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re-establishment of native plant species on the graded surface;
• implementation of long-term groundwater monitoring in accordance with an
approved basewide long-term groundwater monitoring plan;
• installation and maintenance of site perimeter fencing to control site access
including signage warning against unauthorized vehicular traffic;
• implementation of land use restrictions such as preventing construction activities
that would impair the integrity of the existing cover and preventing installation of
monitoring or injection wells in the site area (except where required for
environmental purposes); and
• 5-year site review to assess the effectiveness of the remedy.
Site LF-44. Contaminants of potential concern were not detected in soil samples at LF-44.
Installation of Alternative 2 for Site LF-44 includes the following specific activities:
• removal of surface debris and disposal at an off-site disposal facility;
• implementation of long-term groundwater monitoring in accordance with an
approved basewide long-term groundwater monitoring plan;
• implementation of land use notifications identifying the area as an NFA site; and
• 5-year site review to assess the effectiveness of the remedy.
Additional detail regarding the preferred action for the landfill sites has been presented in the
Closure and Post-Closure Technical Plans for the landfill sites (Montgomery Watson, 1996b). A
contingency plan would be implemented should it be determined that the remedy is no longer
protective of human health and the environment. Contingency plans will be described as
necessary as part of the operations and maintenance (O&M) documentation.
2.5,43 Cost Analysis. A preliminary cost estimate was prepared for the selected
alternatives for each landfill site as part of the OU 3 FS process. Tables 6 through 11 summarize
the cost analysis for the preferred alternative for each site.
2.5.4.4 System Implementation. In an effort to accelerate the remedial process, to
minimize present and future environmental risks, reduce potential impacts to groundwater, and
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facilitate timely transfer of property to the community, cleanup activities have been initiated
under the direction of the USAF, at some of the sites presented in this ROD. These accelerated
actions were performed in agreement with the RPMs including the USEPA, DTSC, Lahontan
RWQCB, and USAF. The accelerated actions were performed at landfill Sites DP-03, DP-04,
LF-12, LF-14, LF-44, and the SEDA as detailed in the Technical Plans for the landfill sites
(Montgomery Watson, 1996b) and the Site Closeout Report for the landfill sites (Montgomery
Watson, 1997c). The actions at the landfill sites began in June 1996 and were completed in April
1997. These actions arc summarized in Section 2.9 (Current Site Status). The effectiveness of
these remedies will be assessed as part of the ongoing O&M and long-term monitoring and will
be the focus of the 5-year site review.
Statutory Determinations for the Landfill Sites
The selected remedies satisfy the statutory requirements of Section 121 of CERCLA, as amended
by SARA, in that the following four mandates are attained:
" The selected remedies are protective of human health and the environment, will
decrease site risks, and will not create short-term risk nor have cross-media
consequences.
• The selected remedies comply with federal and state requirements that are
applicable or relevant and appropriate to the remedial action such as chernical-
specific ARARs, chemical-specific clean-up standards, and action-specific
ARARs.
• The selected remedies are cost-effective in its fulfillment of the nine CERCLA
evaluation criteria through remediation of the landfill sites in a reasonable period
of time.
• The selected remedies utilize permanent solutions and alternative treatment
technologies or resource recovery technologies, to the maximum extent
practicable.
Protection of Human Health and the Environment Protection of human
health and the environment at the OU 3 landfill sites is achieved by the selected remedy for each
site by reducing or eliminating the potential for direct contact with landfill contents and
minimizing infiltration.
*
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2.5.5.2 Compliance with ARARs. All pertinent ARARs identified for the OU 3 landfill
sites (Table 4) will be met by the selected remedies.
Cost Effectiveness. The USEPA, the USAF, and the State of California believe
that the selected remedies fulfill the nine criteria of the NCP and provide overall effectiveness
with respect to their costs.
2.5.5.4 Utilization of Permanent Solution and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Possible. The selected remedy represents, to
the maximum extent to which permanent solutions and treatment technologies can be used, a
cost-effective manner for remediating the OU 3 landfill sites. The remedies selected provide the
best balance of long-term effectiveness and permanence; reduction of TMV through treatment;
short-term effectiveness; implementability and cost effectiveness.
2.5.5.5 Preference for Treatment as a Principle Element The selected remedies will
leave contaminants in place at the OU 3 landfill sites. The size of the landfill sites and the
heterogeneous nature of the wastes present, preclude a remedy in which contaminants could be
excavated and treated effectively. Therefore, the selected remedies do not satisfy the preference
for treatment as a principle element. However, the selected remedies provide a cost-effective
method to reduce the mobility of contaminants.
2.6 TPH/VOC SITE SUMMARY
This section summarizes the site characteristics, risk assessment results, descriptions of the
alternatives evaluated, alternatives comparison, and the selection of the final remedies for the OU
3 TPH/VOC sites potentially requiring action (Sites WP-17, FT-19a, FT-19b, FT-19c, FT-20
{soil], OT-51, and SS-59). Because potential remedial alternatives for Site QT-69 were
evaluated separately (IT, 1995a), this site is discussed separately in Section 2.7.
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2.6.1
Summary of TPH/VOC Site Characteristics and Risk Assessments
The OU 3 TPH/VOC sites presented in this ROD were investigated and evaluated using the same
rationale and investigative techniques, which included a combination of soil-gas and soil
sampling (soil borings, HydroPunch®, and monitoring wells). Table 12 presents a summary of
the OU 3 TPH/VOC site characterizations on a site-specific basis.
Because of the similarities between these sites, they were initially investigated separately from
the other OU 3 sites. The data was presented in the Remedial Investigation Summary Report for
Soil Removal at Miscellaneous OU 3 Sites (M&E, 1994). Detected concentrations were
compared to "initial evaluation criteria" to determine whether FS analysis to assess potential
remedial action was required. The initial evaluation criteria were based on the Leaking
Underground Fuel Tank (LUFT) Manual (LUFT Task Force, 1989) and were presented in the
M&E RI Report as follows for soils less than 30 feet bgs (M&E, 1994):
TPH
benzene
toluene
ethylbenzene
total xylenes
1,000 milligram per kilogram (mg/kg)
1,000 micrograms per kilogram (ug/kg)
50,000 ug/kg
50,000 ug/kg
50,000 ug/kg
The results of the M&E investigation of the TPH/VOC sites were summarized in the subsequent
OU 3 RI Report (Montgomery Watson, 1996a) in which a risk assessment was performed for
each site.
Six of these sites (WP-17, FT-19a, FT-19b, FT-19c, OT-51, and SS-59) had TPH and BTEX
constituents detected in soil at concentrations exceeding the initial evaluation criteria for these
constituents.
*
The risk assessments performed for the TPH/VOC sites indicated that Sites FT-19a, FT-19b, FT-
19c, and FT-20 [soil] had risks exceeding the California benchmark value of 1E-06; however, the
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risks were primarily a result of the presence of inorganics which were considered naturally
occurring.
Two sites had groundwater affected by COPCs (Sites OT-51 and OT-69). Site OT-51 had
detectable concentrations of TPH (extractable as JP-4) and BTEX in the area of contaminated
soil. A detailed risk assessment was not performed for groundwater at Site OT-51 because there
is no completed exposure pathway to receptors (i.e., groundwater is at approximately 120 feet
bgs and is not used as a source for potable water, irrigation, etc., in the vicinity of Site OT-51).
Site OT-69 is defined as the TCE and PCE detected in groundwater in monitoring wells in the
flightline and operations support facilities area. Site OT-69 has been addressed separately in
Section 2.7. The groundwater beneath Sites FT-19a, b, and c is affected by TCE; however, this
contamination is addressed in the final ROD for OU 1 (Montgomery Watson, 1994).
The site characterizations and risk assessments for the TPH/VOC sites requiring remedial action
are summarized below. Additional details regarding the site characterizations and risk
assessments are presented in the OU 3 RI/FS reports (Montgomery Watson, 1996a and 1997a).
2.6.1.1 Site WP-17. Site WP-17 is located near Buildings 551 and 552 in the central
portion of the base. The site consists of a petroleum, oil, and lubricant (POL) leachfield used for
disposal of waste POLs from vehicle maintenance and a fuels laboratory. The following
subsections summarize the site characterization and risk assessment for Site WP-17.
Site Characterization. To characterize Site WP-17, M&E performed investigation activities
including a historical records review, a soil-gas survey, and soil boring installation. Subsurface
samples from the soil borings were collected and analyzed. Data gathered were used by
Montgomery Watson to perform the fate and transport modeling and were also incorporated into
the baseline risk assessment.
Elevated organic vapor analyzer (OVA) readings observed during the soil-gas survey were used
to locate the four initial soil borings. Soil-gas survey results indicated pronounced 0,-CO,
inversions at Site WP-17. The pronounced 0,-CO, inversions could indicate that aerobic
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degradation has occurred and may be occurring. Localized elevated (>200 parts per million
[ppm]) methane levels in locations with strong Oj-CO, inversion suggested that anaerobic
degradation of constituents may be occurring in some areas (M&E, 1994).
Eleven soil borings were advanced to further investigate the soil-gas results and to assess the
presence of POL and fuel constituents at the site. TPH and VOCs were detected in surface and
subsurface samples collected from borings throughout the site. Based on the soil boring
analytical results, it was concluded that detected concentrations exceeded the initial evaluation
criteria (see Section 2.6.1) for TPH and BTEX in the boring adjacent to the oil-water separator at
WP-17 (SBS-06). Concentrations exceeding these criteria were not detected deeper than 25 feet
bgs at this boring. Several of the other borings in the vicinity of the former leachfield showed
detectable concentrations of hydrocarbons and VOCs; however, these were lower than the
evaluation criteria. Based on an assumed depth to groundwater of 120 feet bgs, vadose zone
modeling results indicated that under the base case scenario (best estimate of site conditions for
calibrated model), benzene in the soil water (i.e., the water distributed between the soil particles
in the vadose zone) will not reach the water table and the soil water concentrations will reduce to
less than 1.0 micrograms per liter (ng/L) in 100 years. The TPH constituents detected at Site
WP-17 arc less mobile than benzene; therefore, petroleum hydrocarbons constituents detected at
Site WP-17 are not expected to adversely impact groundwater.
Risk Assessment. As described in Section 2.2.2, a baseline risk assessment was performed for
Site WP-17 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenario evaluated for this site
was the construction worker (potential subsurface soil exposure). This baseline human health
risk assessment estimated the highest excess lifetime cancer risk of 9.7E-07, primarily because of
total chromium. Although this is below the benchmark values for risk assessment, because the
initial evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX
were exceeded in soils at the site, the site was assessed in the OU 3 FS.
The results of the ecological risk assessment indicated that Site WP-17 was not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
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2.6.1.2 Sites FT-19a and FT-19c. Sites FT-19a and FT-19c are fire training areas
located north of the Crosswind/Secondary Runway (Figure 2). Site FT-19a is an older training
area located underneath a formerly concrete-lined training area. In addition to the main area,
smaller areas, also used for fire training, are located south and east of the main training area. The
smaller areas make up Site FT-19c. The following subsections summarize the site
characterization and risk assessment for Sites FT-19a and FT-19c. Groundwater beneath Site
FT-19 is considered part of OU 1.
Site Characterization. To characterize Sites FT-19a and FT-19c, M&E performed investigation
activities including a soil-gas survey, soil boring installation, composite sample dioxin testing
(with a risk assessment), biological testing, and removal activities (with associated confirmation
sampling). Samples from the soil borings and confirmation samples were collected and
analyzed. Data gathered were used by Montgomery Watson to perform the fate and transport
modeling and were also incorporated into the baseline risk assessment.
Concentrations of VOCs in shallow (7 feet bgs) soil-gas points were identified throughout the
site. Thirty-eight soil borings were advanced to investigate the fire training rings and to further
investigate the soil-gas results. Four composite samples from surface soil samples throughout
the site showed detectable concentrations of some dioxin constituents. Based on the application
of total equivalence factors to the dioxin results, M&E reported that the toxicity equivalents
(TEs) were below action levels (M&E, 1994). TPH, VOCs, and SVOCs were detected in surface
and subsurface samples in borings throughout the site. Based on the soil boring analytical
results, it was concluded that petroleum concentrations exceeded the initial evaluation criteria for
TPH and BTEX (based on the LUFT Manual; see Section 2.6.1) in several locations at the sites.
Biological testing suggests that, although some aerobic biological activity may be occurring at
the site, very little anaerobic biological activity was occurring (M&E, 1994). Vadose zone
modeling results indicated that under the base case scenario (best estimate of site conditions for
calibrated model), benzene in the soils at Sites FT-19a and FT-19c will not adversely affect
groundwater quality. However, under die base case scenario, model results predicted that TCE
present in the vadose zone at Site FT-19c would reach the water table within 75 years with
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concentrations increasing to greater than 400 milligrams per liter (mg/L) within 100 years.
Because FT-19 overlies the OU 1 TCE plume and is considered a potential source for this
contamination, the modeling of the groundwater beneath this area has been considered separately
as part of OU 1. The proposed OU 1 treatment system design, including modeling scenarios and
results, is presented in detail in the OU 1 Pre-Design Study (Montgomery Watson, 1995b).
Risk Assessment As described in Section 2.2.2, a baseline risk assessment was performed for
Sites FT-19a and FT-19c for which risk assessment scenarios were evaluated based on the
proposed reuse of the land parcel in which the site is located (USAF, 1993). The scenarios
evaluated for these sites included: industrial/commercial, trespasser/visitor, construction worker
(potential surface soil exposure), and construction worker (potential subsurface soil exposure)
This baseline human health risk assessment estimated the highest lifetime cancer risk of 4.0E-06
for Site FT-19a, primarily because of arsenic under a construction worker (subsurface soils)
scenario. Although this is above the benchmark values for risk assessment, the arsenic at the site
is considered naturally occurring. However, because the initial evaluation criteria (based on the
LUFT Manual; see Section 2.6.1) for TPH and BTEX were exceeded in soils at the site, the site
was assessed in the OU 3 FS.
The baseline human health risk assessment estimated the highest lifetime cancer risk of 3.UE-06
for Site FT-19c, primarily because of chromium under an industrial/commercial scenario.
Although this is above the benchmark values for risk assessment, the chromium at the site is
considered naturally occurring and within background ranges. However, because the initial
evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX were
exceeded in soils at this site and vadose zone modeling indicated TCE in soils may adversely
affect groundwater quality, the site was assessed in the OU 3 FS.
The results of the ecological risk assessment indicated that Sites FT-19a and FT-19c are not areas
of potential ecological concern because of the lack of suitable habitat for environmental
receptors.
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2.6.1.3 Site FT-19b. Site FT-195 is the Medical Waste Disposal Area adjacent to Site
FT-19c (Figure 2). The site is located approximately 800 feet south of the main fire training area
(Site FT-19a). Medical waste was discovered at the site during soil-gas investigations conducted
in the Site FT-19 area in 1987 (Montgomery Watson, 1996a). Because of the unique nature of
Site FT-19b, it was investigated separately from Sites FT-19a and FT-19c. The following
subsections summarize the site characterization and risk assessment for Site FT-19b.
Site Characterization. To characterize Site FT-19b, M&E performed investigation activities
including a soil-gas survey, soil boring installation, composite sample dioxin testing (with a risk
assessment), biological testing, and disposal area assessment with shallow test pits. Samples
from the soil borings and confirmation samples were collected and analyzed. Biological testing
and composite dioxin sampling was performed over the Site FT-19 area as a whole (sites a, b,
and c). Data gathered were used by Montgomery Watson to perform the fate and transport
modeling and were also incorporated into the baseline risk assessment. It was found that the soil
beneath the medical wastes was affected by hydrocarbons and VOCs similar to Sites FT-19a and
FT-19c as detailed below.
Concentrations of VOCs in shallow (7 feet bgs) soil-gas points were identified throughout the
site. Eleven soil borings were advanced to further investigate the soil-gas results and assess the
presence of fuel and VOC constituents at the site. TPH, VOC, and SVOCs were detected in
surface and subsurface samples in borings throughout the site. Based on the soil boring
analytical results, is was concluded that petroleum concentrations exceeded the initial evaluation
criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX in two borings at the
site. TPH was detected to a maximum depth of 25 feet bgs. Vadose zone modeling results
indicated that under the base case scenario (best estimate of site conditions for calibrated model),
the most mobile constituents in the soils at Site FT-19b will not adversely affect groundwater
quality. The disposal area assessment and test pits revealed that medical wastes were present
primarily in the surface soil.
It is believed that the TPH and VOC constituents detected at the site are related to activities at
Sites FT-19a and FT-19c. However, the summary of the site characterization at Site FT-19b
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have been presented separately from Sites FT-19a and FT-19c to be consistent with the original
data presentation in the M&E RI Report (M&E, 1994) and because of the unique site
characteristic of the medical waste being present. The approximate area where medical wastes
were observed was mapped by M&E (M&E. 1994) and is presented in the OU 3 RI Report
(Montgomery Watson, 1996a). The medical wastes at this site have been removed and disposed
of at an off-site disposal facility under the Full Service Remedial Action (FSRA) activities.
Risk Assessment As described in Section 2.2.2, a baseline risk assessment was performed for
Site FT-19b for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this site
included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), and construction worker (potential subsurface soil exposure). This baseline human
health risk assessment estimated the highest excess.lifetime cancer risk of 5.2E-06, primarily
because of incidental ingestion of beryllium and nickel in soils under the industrial/commercial
worker scenario. Although this is above the benchmark value for risk assessment, the beryllium
and nickel detected at the site were considered naturally occurring and within background ranges.
However, because the initial evaluation criteria (based on the LUFT Manual; see Section 2.6.1)
for TPH and BTEX were exceeded in soils at the site, remedial actions were considered in the
OU 3 FS for the TPH and VOCs detected at Site FT-19b.
The results of the ecological risk assessment indicated that Site FT-19b was not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
2.6.1.4
Site FT-20 (Soil)
Site FT-20 (soil) is the reported location of an abandoned fire training area (Figure 2). The site is
located in an unpaved area south of the STP percolation ponds (Site WP-26). Site FT-20 (soil) is
the designation for the soil in this area. The affected groundwater in this vicinity is designated as
FT-20 (groundwater) which is currently an OU 2 site; therefore, it is not addressed further in this
ROD. The following subsections summarize the site characterization and risk assessment for
Site FT-20 (soil).
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Site Characterization. To characterize Site FT-20 (soil), an active soil-gas program was
conducted, five borings were installed, and surface and subsurface (soil boring) samples were
collected and analyzed. Compiled data were used to perform fate and transport modeling and
were also incorporated into a baseline risk assessment.
TCE in shallow soil-gas was detected sporadically throughout the site. Five soil borings were
installed to depths of 15 feet to investigate soil-gas anomalies and reported bum areas. Arsenic,
barium, lead, mercury, zinc, and hydrocarbons were detected sporadically in surface and
subsurface samples above background. Although TCE was detected in the soil-gas, no VOC
contamination was found in the surface or subsurface soil samples. Hydrocarbons were detected
in two surface soil samples at concentrations of 4,200 mg/kg and 8,900 mg/kg. Vadose zone
modeling results showed that even under the most conservative conditions, the most mobile
constituent will not migrate deeper than 20 feet below the bottom of the disturbed areas within
100 years. Therefore, the less mobile contaminants detected at this site are not expected to
migrate significantly below the bottom of the disturbed areas and would pose no threat to the
groundwater.
Risk Assessment. As described in Section 2.2.2, a baseline risk assessment was performed for
Site FT-20 for which risk assessment scenarios were evaluated based on the proposed reuse of
the land parcel in which the site is located (USAF, 1993). The scenarios evaluated for this siie
included: industrial/commercial, trespasser/visitor, construction worker (potential surface soil
exposure), and construction worker (potential subsurface soil exposure). This baseline human
health risk assessment estimated a highest excess lifetime cancer risk of 4.0E-05, primarily
because of arsenic under an industrial/commercial scenario. Although this is above the
benchmark value for risk assessment, the arsenic at the site is considered naturally occurring and
within the background range. However, because elevated concentrations of petroleum
hydrocarbons were detected in surface samples, the site was assessed in the OU 3 FS.
The results of the ecological risk assessment indicated that Site FT-20 (soil) is not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
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2.6.1.5 Site OT-51/SS-59. The location of Site OT-51 is shown on Figure 2. The site
consists of five engine test cells. The section of the site designated as OT-51 is located near
engine test cell Facilities 799 and 807. Periodic jet fuel spills have reportedly occurred at the site
during testing. The section of the site designated as SS-59 is located near Facility 819. Site SS-
59 is the reported location of an 8,000-gallon jet fuel spill. The two remaining test cells are
located in revetments south of Site SS-59. Because the sites are closely related, they were
combined for investigation activities. The following subsections summarize the site
characterization and risk assessment for Site OT-51/SS-59.
Site Characterization. To characterize Site OT-51/SS-59, M&E performed investigation and
removal activities including soil boring and monitoring well installation, and UST and septic
system removal. Surface and subsurface samples from the soil borings were collected and
analyzed. Based on preliminary analytical data collected by M&E, Montgomery Watson
performed subsequent investigations at a "hot spot" identified at Site OT-51. The additional
investigation activities at Site OT-51 included: subsurface soil sampling during installation of
HydroPunch® borings, soil borings, and monitoring wells; downhole geophysics; aquifer testing;
and groundwater sampling. Data gathered from the M&E and Montgomery Watson
investigations were used by Montgomery Watson to perform the fate and transport modeling and
were also incorporated into the baseline risk assessment.
The results of the M&E investigations at Site OT-51/SS-59 are presented in detail in the M&E
RI Report (M&E, 1994) and arc summarized in the OU 3 RI Report (Montgomery Watson,
1996a). Based on the initial evaluation criteria presented in the M&E RI Report (based on the
LUFT Manual; see Section 2.6.1), it was concluded that no further action was warranted at the
soil ocrm at Facility 807 or the two revetment engine test cells south of SS-59. However,
consideration of potential remedial action warranted at Facility 819 (Site SS-59) and further
investigation was required at the soil berm at Facility 799 (Site OT-51) to define the extent of
constituent concentrations exceeding the initial evaluation criteria for TPH and BTEX.
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Subsequent investigations at Site OT-51, performed by Montgomery Watson to fill general data
needs, included collection of subsurface soil samples and groundwater sampling. Results of this
investigation showed that detectable concentrations of TPH and BTEX are present in the
groundwater in the area of the hot spot identified during the M&E investigations. Monitoring
wells installed upgradient (WZ-05) and downgradient (MW-1) showed no detectable
concentrations of TPH (extractable as JP-4) or BTEX during the September 1994 sampling
event. However, TPH (extractable as JP-4) and BTEX were detected in monitoring wells WZ-04
and WZ-06 (installed in the area of the hot spot), and in crossgradient HydroPunch® borings
SBS-25 and SBS-27. Soil sampling confirmed the elevated hydrocarbon constituent
concentrations reported by M&E with the highest concentrations of TPH (extractable as JP-4)
and BTEX occurring in samples collected from WZ-04. Soil sampling from the M&E and
Montgomery Watson investigations confirmed that the elevated TPH and VOC concentrations in
the soil are primarily limited to the area of the hot spot. Occasional hits of TPH and BTEX
compounds are present in some surrounding borings, with the highest detected concentrations
occurring at depths of approximately 100 feet bgs. Vadose zone modeling results indicated that
under the base'case scenario (best estimate of site conditions for calibrated model), benzene in
the soil will continue to reach the water table over the 100 years modeled. Based on the fact that
groundwater is affected by TPH and VOCs beneath Site OT-51, and vadose zone modeling
results, the affected groundwater was also modeled for the site using benzene as an indicator
compound. Results of this modeling indicated that over 50 years, the migration of benzene
leaching from the vadose zone will be limited. The base case scenario indicated that the leading
edge of a 0.5 ug/L benzene plume boundary would migrate approximately 400 feet from the
source area.
After the completion of the remedial investigations at the site in September 1994, subsequent
sampling rounds were performed as part of the basewide long-term monitoring plan in
September 1995, January 1996, May 1996, October 1996, February 1997, and July 1997
(Montgomery Watson, 1996c,d,e,f; Montgomery Watson, 1997d,e,f). All four monitoring wells
had detectable concentrations of TPH and BTEX in the September 1995 sampling event.
Concentrations of most of these compounds increased in subsequent sampling rounds, with peak
values in January and May 1996, after which concentrations generally decreased. BTEX
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compounds were near or below detection limits during the last sampling event (July 1997), and
TPH values ranged from <50 mg/L (non-detect) to 120 mg/L.
Risk Assessment Preliminary Remediation Goal (PRO) screening in accordance with the
methodology presented in the OU 3 RI indicated that further human health risk analysis was not
required because confirmed contamination was at depths that would not affect receptors in the
risk assessment scenarios. However, because the initial evaluation criteria (based on the LUFT
Manual as presented in the M&E RI Report [M&E, 1994]) for TPH and BTEX were exceeded in
soils at the site and because groundwater quality is affected, the site was assessed in the OU 3
FS.
The results of the ecological risk assessment indicated that Site OT-51/SS-59 is not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
2.6.2 • Description of TPH/VOC Site Alternatives
Based on the results of remedial investigations, it was determined that remedial action was
potentially necessary at OU 3 TPH/VOC Sites WP-17, FT-19a, FT-19b, FT-19c, OT-51. and SS-
59 to protect groundwater quality. An FS analysis was performed for these sites as described for
the landfill sites in Section 2.5.2. Alternatives were developed and evaluated for the TPH/VOC
sites as a group because of the similarity between the sites with respect to contaminant type,
distribution, site characteristics, and potential actions. The RAOs established for the OU 3
TPH/VOC sites are summarized below:
Soil Site?. The RAOs developed for the soils at the TPH/VOC sites are summarized below.
Protection of Human Health
Prevent human exposure to soil having 1E-04 to 1E-06 excess cancer risk from all
carcinogens.
Prevent human exposure to soil having noncarcinogens in excess of reference
doses (RfDs).
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Protection of the Environment
• Reduce the TMV of the contamination in unsaturated soil to reduce the potential
migration of contaminants to groundwater.
Remove, to the extent practical, the COPCs detected in unsaturated soils to meet
or exceed the remediation goals discussed below.
To protect groundwater quality, remediation goals for the BTEX and TPH in soils were
determined in the FS based on the LUFT Field Manual (LUFT Task Force, 1989) by completing
the scoring system presented in the LUFT manual for a general site at GAFB. Figure 9 presents
the remediation goals for TPH and BTEX in the form of depth-specific levels relative to the
groundwater table. The depth to groundwater for the TPH/VOC sites is approximately 120 feet
bgs.
The LUFT manual does not provide a method for determining remediation goals for TCE (the
primary constituent of concern for Site FT-19c); therefore, remediation goals were determined
using SESOIL modeling as detailed in the OU 3 FS Report (Montgomery Watson, 1997a). A
graphical presentation of the levels of TCE that must be obtained are presented on Figure 10.
Based on these remediation goals, a remedy would be implemented and operated until the mass
of contaminants remaining was such that no impact to groundwater was anticipated. Prior to
closure of a TPH/VOC site for which a remedy has been implemented, confirmation samples
(soil and vapor) would be collected as necessary to demonstrate that soil cleanup levels presented
on Figures 9 and 10 are achieved. If contamination remaining in soil can be demonstrated to
have no impact to groundwater quality, concentrations remaining in soil may exceed the
numerical values presented in Figures 9 and 10, and the site may be considered for closure.
Groundwater Sites. There are currently no complete exposure pathways for the contaminated
groundwater at Site OT-51. Groundwater in the site area is not used as a source of domestic,
industrial, or agricultural supply. Therefore, there is currently no danger of adverse exposure to
either base personnel or residents. In addition, the groundwater does not reach the ground
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surface within the base boundaries; therefore, there is no known current exposure pathway to
ecological receptors.
However, in accordance with ARARs which call for protection of groundwater resources,
groundwater at Site OT-51 should be protected. Therefore, the RAO for groundwater is as
follows:
• Reduce the dissolved concentrations for identified COPCs in the groundwater
beneath Site OT-51 so that the most stringent concentrations identified in the
ARARs are not exceeded (maximum contaminant levels [MCLs], secondary
MCLs, or quantifiable taste or odor criteria).
The groundwater numerical cleanup standards for Site OT-51 are presented on Table 13.
Remedial alternatives were developed for the TPH/VOC sites from an analysis of remedial
technologies as part of the OU 3 FS (Montgomery Watson, 1997a). The alternatives, with their
components, are presented in the following sections as applicable for soil and groundwater.
Soil Alternatives. Four remedial alternatives were developed for the TPH/VOC-affected soils
from an analysis of remedial technologies as part of the OU 3 FS (Montgomery Watson, 1997a).
The four alternatives, with their components, are as follows:
Alternative 6 (No Action for Soil)
1) Groundwater Monitoring
2) 5-Year Site Review
Alternative? (Removal/Disposal)
1) Removal of Contaminated Soils
2) Transport of Soils to Off-Site Treatment/Disposal Facility
3) .Surface Restoration
Alternatives (Soil Vapor Extraction [SVE])
1) Installation of SVE System to Remediate Soils
2) Groundwater Monitoring
3) Access Restrictions
4) Land Use Restrictions
5) 5-Year Site Review
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Alternative 9 (Bioventing)
I) Installation of Bioventing System to Remediate Soils
2) Groundwater Monitoring
3) Access Restrictions
4) Land Use Restrictions
5) 5-Year Site Review
Groundwater Alternatives. Two remedial alternatives were developed for TPH/VOC-affected
groundwater at Site OT-51 from an analysis of remedial technologies as part of the OU 3 FS
(Montgomery Watson, 1997a). The alternatives, with their components, are as follows:
Alternative 10 (No Action for Groundwater)
1) Groundwater Monitoring
2) 5-Year Site Review
Alternative 11 (Oxygen Enhanced Bioremediation)
1) Land Use Restrictions
2) Use of an oxygen-releasing chemical (i.e., Oxygen Release Compound
[ORCJ® or hydrogen peroxide [rLOJ) in existing wells if COPCs in
downgradient monitoring wells do not meet groundwater numerical cleanup
standards (Table 13) within a sufficient time frame
3) Groundwater Monitoring
4) 5-Year Site Review
2.6.2.1 Alternative 6: No Action for SoiL As required by the NCP, the no action
alternative serves as a baseline against which other TPH/VOC soil alternatives are compared. Its
components include groundwater monitoring and the 5-year site review.
Groundwater monitoring at the OU 3 TPH/VOC sites would be part of an approved basewide
long-term monitoring plan for GAFB. Selected monitoring wells at each site would be sampled
annually, semi-annually, or quarterly, to determine if TPH/VOC contaminants are leaching to the
groundwater. Additional monitoring wells may be required to satisfy this monitoring component
(i.e., at Site OT-51).
The no-action alternative would leave TPH/VOC-affected soils in place with no closure activities
undertaken; however, natural degradation of the TPH and VOCs would occur. Because
contaminants would remain on site, a site review would be conducted every 5 years as required
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by CERCLA. The purpose of the 5-year site review and long-term monitoring would be to
assess the effectiveness of the alternative.
2.6.2.2 Alternative 7: Removal/Disposal. Alternative 7 includes removal of
contaminated soils, transport to an off-site treatment/disposal facility, and surface restoration.
For this alternative, backhoes and dump trucks would be used to remove affected soils. Surface
restoration would involve importing clean fill and restoring the excavated area to a level,
compacted surface. Affected soils would be transported to the off-site treatment/disposal facility
and clean fill would be imported with dump trucks. Some demolition and/or cutting of existing
concrete pads would be required (i.e., at Site SS-59).
It is assumed that, after the contaminated soils are removed from the site, there would be closure
on the site and continued groundwater monitoring would not be conducted and the 5-year site
review would not be required.
2.6.23 Alternative 8: Soil Vapor Extraction. Alternative 8 consists of using SVE to
remediate soil with confirmation sampling, groundwater monitoring, land use and access
restrictions, and 5-year site review.
SVE is a soil remediation technology that uses vacuum blowers to pull large volumes of air
through contaminated soil. The air flow sweeps out the soil gas, causing desorption of volatile
contaminants from the soil into the vapor phase. A schematic of a typical SVE system design is
presented in Figure 11.
SVE for soil would be achieved using a series of extraction vents. Monitoring points would be
installed for soil vapor sampling to facilitate a pilot test study at the site and for subsequent
system evaluation. A schematic for a typical monitoring point and vapor sampling apparatus is
presented on Figure 12.
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To evaluate system performance for this alternative, confirmation samples would be collected
and groundwater monitoring would be performed. Confirmation sampling to determine
completion of the remediation could include soil and vapor.
In addition, land use and access restrictions would be employed until the remediation is
confirmed to be complete. Land use restrictions would prohibit disturbance of affected soils and
restrict installation of wells for use other than groundwater monitoring. Access restrictions
would protect the remedy while in place and would be achieved through fencing and/or standard
security procedures minimizing access from unauthorized personnel. When the remediation is
complete, the restrictions described above would be reassessed by the appropriate regulatory
agencies as part of the 5-year site review. The purpose of the 5-year site review and monitoring
would be to assess the effectiveness of the alternative.
2.6.2.4 Alternative 9: Bioventing. Alternative 9 consists of using in situ bioventing to
remediate soil with confirmation sampling, groundwater monitoring, land use and access
restrictions, and 5-year site review.
Bioventing uses forced aeration to stimulate soil-indigenous microorganisms to aerobically
metabolize organic compounds in unsaturated soils. Depending on air flow rates, VOCs may be
simultaneously removed through volatilization. A schematic of a typical bioventing system is
presented in Figure 13.
To evaluate system performance for this alternative, confirmation samples would be collected
and groundwater monitoring would be performed. Confirmation sampling to determine
completion of the remediation could include soil samples and vapor samples.
In addition, land use and access restrictions (as described in Section 2.6.2.3), and 5-year site
review would be employed until remediation is confirmed complete as described for Alternative
8.
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2.6.15 Alternative 10: No Action for Groundwater. As required by the NCP, the no
action alternative serves as a baseline against which other TPH/VOC groundwater alternatives
are compared. Its components include groundwater monitoring and the 5-year site review.
Selected monitoring wells would be sampled annually, semi-annually, or quarterly, to monitor
constituents present in the groundwater. Additional monitoring wells may be required to satisfy
groundwater monitoring requirements.
The no-action alternative would leave TPH/VOC-affected groundwater in place with no closure
activities undertaken. Because contaminants would remain on site, a site review would be
conducted every 5 years as required by CERCLA. The groundwater monitoring and 5-year site
review would be used to assess the effectiveness of the alternative.
2.6.2.6 Alternative 11: Oxygen Enhanced Bioremediation. Alternative 11 consists of
land use restrictions, use of oxygen-releasing chemicals (i.e., ORC® or H,O,) in existing
monitoring wells if COPCs in downgradient monitoring wells do not meet groundwater
numerical cleanup standards (Table 13) within a sufficient time frame, groundwater monitoring,
and 5-year site review.
With this alternative, the implementation of land use restrictions at the site would restrict access
to the affected groundwater and prohibit disturbance of existing monitoring wells and
appurtenances. Administrative measures would be taken to ensure that groundwater is not used
for domestic uses (i.e., drinking or irrigation).
The top portion of the groundwater would be oxygenated through the use of oxygen-releasing
chemicals (i.e., ORC® or H,O,) in the existing monitoring wells to accelerate natural
biodegradation. ORC® is a fine, insoluble magnesium peroxide compound that slowly releases
oxygen when it is activated by moisture. The oxygenation would enhance the degradation of
fuels and VOCs by naturally occurring aerobic microorganisms. ORC® is a passive process
which does not disturb the hydraulics of the plume. Installation would consist of installing an
appropriate number of inert filter socks containing the ORC® compound into the groundwater
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via the existing monitoring wells. The ORC® socks would require replacement every 6 to 12
months, depending on the concentrations of constituents in the groundwater.
Similarly, H2O2 can be used to oxygenate the groundwater by injecting a dilute solution into the
contaminated groundwater zone. For comparison purposes, the discussion that follows,
including the cost analysis, assumes the use of ORC®.
The groundwater monitoring and 5-year site review would be used to assess the effectiveness of
the alternative.
Subsequent to the remedial investigations at Site OT-51, groundwater at the site has been
routinely monitored as part of the Basewide Long-Term Groundwater Monitoring Plan
(Montgomery Watson, 1995c and 1996c). The groundwater data collected since September 1995
at Site OT-51 as part of the long-term groundwater monitoring effort (Montgomery Watson,
1996d,e,f; 1997d,e,f) have indicated that the COPCs in groundwater increased slightly and then
began decreasing. It is expected that the plume will be below detectable levels of benzene in 5
years. Under this alternative, if subsequent rounds of long-term monitoring do not continue to
show the trend of decreasing levels of COPCs, the contingent task of installation of the oxygen-
releasing chemicals described above would be implemented.
2.63 Summary of Comparative Analysis of Alternatives for the TPH/VOC Sites
The remedial alternatives developed were analyzed in detail using the nine evaluation criteria
required by the NCP as detailed in Section 2.5.3 for the landfill sites.
The resulting strengths and weaknesses of the alternatives were then weighed to identify the
alternative providing the best balance among the nine criteria. Table 14 summarizes this
comparison.
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'2.6 J.I Overall Protection of Human Health and the Environment This criterion was
defined in Section 2.5.3.1 for the landfill sites. The comparative analysis for this criterion for the
TPH/VOC sites is presented below.
Soil:
Alternative 6: This alternative does not provide any direct protection of human health arid the
environment at any of the TPH/VOC soil sites because no cleanup activities are undertaken.
Alternative 7: The overall protection of human health and the environment is high at the
applicable sites (FT-20 [soil] and SS-59). This alternative removes the potential for direct
contact with TPH/VOC-affected soils through removal, treatment, and disposal, and reduces the
potential for further leaching to the groundwater.
Alternative 8: The overall protection of human health and the environment is high at the
applicable site (FT-19c). This alternative would reduce the levels of TPH/VOC constituents in
soils to below remediation goals.
Alternative 9: The overall protection of human health and the environment is high at the
applicable sites (WP-17, FT-l9a, FT-19b, and OT-51). This alternative would reduce the levels
of TPH constituents in soils to below remediation goals.
Groundwater (Site OT-51):
Alternative 10: This alternative does not provide any additional direct protection of human
health and the environment because no enhanced remedial activities are undertaken and access to
the affected groundwater is not restricted. The process of natural attenuation would occur.
Alternative 11: This alternative provides overall protection of human health and the
environment through land use and deed restrictions prohibiting installation of domestic supply
wells until remediation can be demonstrated. This alternative enhances natural degradation of
contaminants.
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2.6.3.2 Compliance with ARARs, The definition of ARARs and this criterion was
presented in Section 2.5.3.2 for the landfill sites. Final ARARs for the OU 3 landfill sites were
established through discussions between the Lahontan RWQCB, DTSC, USEPA, and USAF. A
listing of agreed upon federal and state laws and regulations that are ARARs for the OU 3
TPH/VOC sites is provided in Table 15.
Soil:
Alternative 6: May not comply with all ARARs at all TPH/VOC sites because the existing
contamination remains in place with no active remediation to achieve cleanup goals.
Alternative 7: The active removal of contaminated soils and subsequent appropriate disposal is
expected to comply with the ARARs for TPH/VOC sites.
Alternative 8: The active remediation of contaminated soils through S VE is expected to comply
with the ARARs for TPH/VOC sites.
Alternative 9: The active remediation of contaminated soils through bioventing is expected to
comply with the ARARs for TPH/VOC sites.
Groundwater (Site OT-51):
Alternative 10: May not comply with all ARARs for groundwater because no enhanced
remediation of the groundwater plume is undertaken. Although natural attenuation processed
would occur, the state considers movement of the plume as a discharge which violates State
Water Resources Control Board Resolution 68-16; an ARAR for this site.
Alternative 11: This alternative is expected to comply with ARARs. Specifically, the proposed
action is expected to enhance biodegradation and address threatened impacts to waters of the
state.
2.63.3 Long-Term Effectiveness and Permanence. This criterion was defined in
Section 2.5.3.3 for the landfill sites. The comparative analysis for this criterion for the
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TPH/VOC sites is presented below. All of the TPH/VOC alternatives satisfy the RAO on
groundwater monitoring to assess potential migration of constituents to groundwater.
Soil:
Alternative 6: This alternative does not provide an active method to satisfy the RAOs for
preventing human exposure to soils having excess risk, to reduce concentrations of contaminants
to meet remediation goals, and to reduce the TMV of contaminants. However, the natural
degradation of fuel constituents would occur. Therefore, the risks from direct contact with the
TPH/VOC-affected soils remains unchanged.
Alternative 7: This alternative satisfies all of the RAOs at the applicable sites (FT-20 [soil] and
SS-59); therefore, long-term effectiveness of this alternative is expected to be high.
Alternative 8: This alternative satisfies all of the RAOs at the applicable site (FT-19c);
therefore, long-term effectiveness of this alternative is expected to be high. SVE has proven to
be effective in remediating soil contaminated with VOCs to below target remediation goals. In
addition, the aeration of the soil via vapor extraction may encourage biological degradation of
TPH constituents.
Alternative 9: This alternative satisfies all of the RAOs at the applicable sites (WP-17, FT-19a,
FT-19b, and OT-51); therefore, long-term effectiveness of this alternative is expected to be high.
Bioventing has proven to be effective in remediating soil contaminated with hydrocarbons to
below target remediation goals.
Groundwater (Site OT-51):
Alternative 10: This alternative does not satisfy the RAOs for preventing human exposure to
contaminated groundwater having excess risk. Therefore, the risks from direct contact with the
affected groundwater remain unchanged.
Alternative 11: For this alternative, restriction of access to the affected groundwater provides a
permanent solution. Biodegradation would ultimately reduce the contaminant concentrations.
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2.63.4 Reduction of Toxicity, Mobility, and Volume through Treatment. This
criterion was defined in Section 2.5.3.4 for the landfill sites. The comparative analysis for this
criterion for the TPH/VOC sites is presented below.
Soil:
Alternative 6: This alternative provides no active reduction of TMV of TPH/VOC-affected
soils at any of the sites.
Alternative 7: This alternative would reduce the TMV of soil contaminants at the applicable
sites (FT-20 [soil] and SS-59) by physically removing, treating, and ultimately disposing of the
affected soils.
Alternative 8t SVE would reduce the TMV of soil contaminants at the applicable site (FT-19c).
Alternative 9: Bioventing would reduce the TMV of soil contaminants at the applicable sites
(WP-17, FT-19a, FT-19b, and OT-51).
Groundwater (Site OT-51):
Alternative 10: This alternative provides no enhanced reduction of TMV of TPH/VOC-affected
groundwater at Site OT-51. The total mass of contaminants is reduced by degradation and the
concentrations are reduced by natural attenuation to below groundwater numerical cleanup
standards. The volume of affected groundwater is not reduced; however, the volume of water
that contains constituents above numerical cleanup standards would be reduced. Mobility is not
actively reduced; however, results of groundwater modeling for the site indicated that over 50
years, the benzene leaching from the vadose zone would not migrate far from the source areas.
The base case model scenario indicated that the leading edge of a 0.5 ug/L benzene plume
boundary would migrate approximately 400 feet from the source area.
Alternative 11: This alternative provides enhancement of the naturally occurring reduction of
TMV of TPH/VOC-affected groundwater at Site OT-51. The total mass of contaminants is
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reduced by degradation and the concentrations are reduced to below groundwater numerical
cleanup standards. The volume of affected groundwater is not reduced; however, the volume of
water that contains constituents above numerical cleanup standards would be reduced. Mobility
is not actively reduced; however, results of groundwater modeling for the site indicated that over
50 years, the benzene leaching from the vadose zone would not migrate far from the source areas.
The base case model scenario indicated that, left untreated, the leading edge of a 0.5 ug/L
benzene plume boundary would migrate approximately 400 feet from the source area.
Additional groundwater monitoring beyond Alternative 10 would provide data to allow efficient
evaluation of the natural degradation and potential migration of contaminants at the site.
Oxygenation of top portion of the groundwater with oxygen-releasing chemicals would
accelerate natural degradation of constituents.
2.6.3.5 Short-Term Effectiveness. This criterion was defined in Section 2.5.3.5 for the
landfill sites. The comparative analysis for this criterion for the TPH/VOC sites is presented
below.
Soil:
Alternative 6: This alternative entails no risks to construction workers because no cleanup
activities arc undertaken at any site. In addition, no short-term public health and environmental
impacts would be expected from this alternative.
Alternative 7: Short-term public health and environmental impacts associated with this
alternative at the applicable sites (FT-20 [soil] and SS-59) are expected to be minimal. Site
remediation workers would need to take appropriate precautions during removal and transport of
affected soils.
Alternative 8: Short-term public health and environmental impacts associated with this
alternative at the applicable site (FT-19c) are expected to be minimal. Site remediation workers
would need to take appropriate precautions during installation and operation of the SVE system.
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Alternative 9: Short-term public health and environmental impacts associated with this
alternative at the applicable sites (WP-17, FT-19a, FT-19b, and OT-51) are expected to be
minimal. Site remediation workers would need to take appropriate precautions during
installation and operation of the bioventing systems.
Groundwater (Site OT-51):
Alternative 10: This alternative entails no risks to construction workers because no cleanup
activities are undertaken at the site. In addition, no short-term public health and environmental
impacts would be expected from this alternative.
Alternative 11: Short-term public health and environmental impacts associated with this
alternative are expected to be minimal. Site remediation workers would need to take appropriate
precautions during installation of the selected soil remediation system and use of oxygen-
releasing chemicals in the existing monitoring wells.
2.63.6 Implementability. This criterion was defined in Section 2.5.3.6 for the landfill
sites. The comparative analysis for this criterion for the TPH/VOC sites is presented below.
Soil:
Alternative 6: This alternative is easily implemented because no closure activities are under
taken. Groundwater monitoring is easy to implement and the materials required are readily
available. There are no administrative difficulties associated with this alternative.
Alternative 7: Removal and disposal of soils is a feasible technology and is easily implemented
for shallow contamination (i.e., Sites FT-20 [soil] and SS-59). Materials and services required
are readily available.
Alternative 8: SVE is a demonstrated technology that is readily implemented. Materials and
services required are readily available. There are no administrative difficulties associated with
this alternative.
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Alternative 9: Similar to Alternative 8, bioventing is a demonstrated technology that is readily
implemented. Materials and services required are readily available. There are no administrative
difficulties associated with this alternative.
Groundwater (Site OT-51):
Alternative 10: This alternative is easily implemented because no closure activities are under
taken. Groundwater monitoring is easy to implement and the materials required are readily
available. There are no administrative difficulties associated with this alternative.
Alternative 11: Use of oxygen-releasing chemicals (i.e., ORC®) in the existing monitoring
wells is relatively easy. All services and materials required are readily available.
2.63.7 Cost. This criterion was defined in Section 2.5.3.7 for the landfill sites. Table 16
presents a summary of the remedial alternative costs for the TPH/VOC sites. Costs are presented
on a present-worth basis over a period of 30 years, with a discount rate of 7 percent. Detailed
cost analysis is presented in the FS (Montgomery Watson, 1997a).
2.63.8 State Acceptance. This criterion was defined in Section 2.5.3.8 for the landfill
sites. Final application of this criterion will occur in the approval of this ROD. The comparative
analysis for this criterion for the TPH/VOC sites is presented below.
Soil:
Alternative 6: It is likely the state would not accept this alternative for most TPH/VOC sites
because no active steps are taken to achieve the RAOs. However, this alternative may be
acceptable for shallow contamination at levels near or below the remediation goals (i.e., FT-19b,
FT-20 tsoil], and SS-59).
Alternative 7: It is likely the state would accept this alternative for shallow TPH/VOC
contamination because the affected soils are completely removed.
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Alternative 8: It is likely the state would accept this alternative for the applicable site (Site FT-
19c) because the contaminants are actively removed from the site.
Alternative 9: It is likely the state would accept this alternative for the applicable sites (Site
WP-17 and FT-19a) because the contaminants are actively degraded during the bioventing
process.
Groundwater (Site OT-S1):
Alternative 10; The state may not accept this alternative because no steps are taken to enhance
the natural processes that would ultimately achieve the RAOs.
Alternative 11: The state is likely to accept this alternative because the remedy would reduce
the contaminants in the state's waters with enhanced biodegradation.
2.6.3,9 Community Acceptance. As defined in Section 2.5.3.9 for the landfill sites,
Community acceptance indicates the public support for a given alternative. Section 3.0 of this
ROD documents the community acceptance of the selected remedies, as presented in the
Proposed Plan (Montgomery Watson, 1997b). Section 3.0 includes a responsiveness summary
that addresses the comments received during the public comment period. The community did
not express any significant objections to the selected remedies during the public meeting or
public comment period.
2,6.4 The Selected Remedies for the TPH/VOC Sites
This section provides a description of the preferred alternatives for remediation of the OU 3
TPH/VOC sites based on the detailed evaluation of alternatives presented in the OU 3 FS
(Montgomery Watson, 1997a). This section includes the basis for selection of a preferred
alternative, a description of the preferred alternative, and cost analyses.
2.6.4.1 Selection of the Preferred Alternatives. The RAOs established for the
TPH/VOC sites in the OU 3 FS are summarized in Section 2.6.2. An evaluation of the
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alternatives with respect to the nine CERCLA criteria resulted in the selection of the following
preferred alternatives to meet the RAOs for the TPH/VOC sites.
Site WP-17. Under the construction worker scenario (subsurface soils), the baseline human
health risk assessment estimated the highest cancer risk of 9.7E-07 for this TPH/VOC-affected
soil site, primarily because of the presence of total chromium found in subsurface soils. This risk
value is below the California and USEPA acceptable benchmark value of l.OE-06. However, the
initial evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX
were exceeded in the soils at the site.
The results of the ecological risk assessment indicated that Site WP-17 was not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
In order to satisfy the RAOs for preventing human exposure to contaminated soils, to reduce
concentrations of contaminants to meet remediation goals, and to reduce the TMV of
contaminants, Alternative 9 (Bioventing) was recommended for Site WP-17 in the OU 3 FS.
Alternative 6 (No Action) is not capable of satisfying these RAOs. The technologies
incorporated in Alternative 7 (Removal/Disposal) were screened out as not applicable for Site
WP-17 because of the prohibitive costs associated with the volumes of soil that would be
required to be removed. The technologies incorporated for Alternative 8 (SVE) were screened
out as not applicable for Site WP-17 because, although SVE encourages biodegradation of TPH
constituents, it is less effective and more costly than bioventing.
Therefore, Alternative 9 (Bioventing) was the selected remedy for Site WP-17. The bioventing
system has been installed as discussed in Section 2.9. The system became operational in
February 1996 and it is anticipated that remedy completion will be achieved within 5 years.
Site FT-19a. Under the construction worker (subsurface soils) scenario, the baseline human
health risk assessment estimated the highest lifetime cancer risk of 2.8E-06 for Site FT-19a,
primarily because of the presence of arsenic. Although this is above the benchmark values for
risk assessment, the arsenic at the site is considered naturally occurring. However, the initial
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evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX were
exceeded in soils at the site.
The results of the ecological risk assessment indicated that Site FT-19a was not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
In order to satisfy the RAOs for preventing human exposure to contaminated soils potentially
posing excess risk, to reduce concentrations of contaminants to meet remediation goals, and to
reduce the TMV of contaminants. Alternative 9 (Bioventing) was recommended for Site FT-19a
in the OU 3 FS. Alternative 6 (No Action) is not capable of satisfying these RAOs. The
technologies incorporated in Alternative 7 (Removal/Disposal) were screened out as not
applicable for Site FT-19a because of the prohibitive costs associated with the volumes of soil
that would be required to be removed. The technologies incorporated for Alternative 8 (SVE)
were screened out as not applicable for Site FT-19a because, although SVE encourages
biodegradation of TPH constituents, it less effective and more costly than bioventing.
Therefore, Alternative 9 (Bioventing) was the selected remedy for Site FT-19a. The bioventing
system has been installed as discussed in Section 2.9. The system became operational in April
1996 and it is anticipated that remedy completion will be achieved within 5 years.
Site FT-19b. The initial evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for
TPH and BTEX were exceeded in soils at the site; therefore, the site was evaluated in the OU 3
FS. However, the contamination at the site appears to be limited in distribution with
concentrations of TPH not detected below 25 feet bgs (M&E, 1994). Vadose zone modeling
results indicated that under the base case scenario (best estimate of site conditions for calibrated
model), the most mobile constituents in the soils at Site FT-19b will not adversely affect
groundwater quality. A subsequent risk assessment indicated that under the
industrial/commercial worker scenario, the baseline human health risk assessment estimated the
highest lifetime risk of 5.2E-06 for the site, primarily because of the presence of beryllium and
nickel. Although this is above the benchmark value for risk assessment, the beryllium and nickel
detected at the site is considered naturally occurring and within background range. The results of
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the ecological risk assessment indicated that Site FT-19b is not an area of potential ecological
concern because of the lack of suitable habitat for environmental receptors. The medical wastes
at this site have been removed and disposed at an off-site disposal facility under the FSRA
activities ongoing at the base.
Based on the detailed analysis of alternatives, Alternative 6 (No Action) was recommended for
Site FT-19b in the OU 3 FS. The technologies incorporated in Alternative 7 (Removal/Disposal)
were screened out as not applicable for Site FT-19b because of the prohibitive costs associated
with the volumes of soil that would be required to be removed. The technologies incorporated
for Alternative 8 (SVE) were screened out as not applicable for Site FT-19b because, although
SVE encourages biodegradation of TPH constituents, this technology is used primarily to
encourage volatilization of VOC contamination. Alternative 9 (Bioventing), is less costly than
SVE and more effective for treating TPH contamination. However, given the limited distribution
of detected TPH and VOCs, vadose zone model results indicating that groundwater quality will
not be adversely affected, and risk assessment results indicating excess risk are the result of
metals considered naturally occurring, remedial action at the associated costs are not believed to
be warranted. Therefore, the no action alternative is the selected remedy at this site.
Groundwater monitoring will be performed for this area as part of the remedial actions to be
performed for Sites FT-19a and FT-19c; therefore, there would be no costs associated with the no
action alternative for this site.
Site FT-19c. Under the construction worker (subsurface soils) scenario, the baseline human
health risk assessment estimated the highest lifetime cancer risk of 3.1E-06 for Site FT-19c,
primarily because of chromium under a construction worker (subsurface soils) scenario.
Although this is above the benchmark values for risk assessment, the chromium at the site is
considered naturally occurring and within background ranges. However, the initial evaluation
criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX were exceeded in
soils at the site. In addition, vadose zone modeling results indicate that TCE present in soils will
adversely affect groundwater beneath the site.
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The results of the ecological risk assessment indicated that Site FT-19c was not an area of
potential ecological concern because of the lack of suitable habitat for environmental receptors.
In order to satisfy the RAOs for preventing human exposure to contaminated soils, to reduce
concentrations of contaminants to meet remediation goals, and to reduce the TMV of
contaminants. Alternative 8 (SVE) was recommended for Site FT-19c in the OU 3 FS.
Alternative 6 (No Action) is not capable of satisfying these RAOs. The technologies
incorporated in Alternative 7 (Removal/Disposal) were screened out as not applicable for Site
FT-19c because of the prohibitive costs associated with the volumes of soil that would be
required to be removed. The technologies incorporated in Alternative 9 (Bioventing) were
screened out as not applicable for Site FT-19c because bioventing would not be effective at
removing the TCE detected in the subsurface soils at the site.
Therefore, Alternative 8 (SVE) was the selected remedy for Site FT-19c. The SVE system has
been installed as discussed in Section 2.9. The system became operational in March 1996 and it
is anticipated that remedy completion will be achieved within 5 years.
Site FT-20 (Soil). The baseline human health risk assessment estimates the highest excess
lifetime cancer risk of 4.0E-06, primarily because of arsenic under an industrial worker,
construction worker, and trespasser scenario. Although this is above the benchmark values for
risk assessment, the arsenic at the site is considered naturally occurring and within the
background ranges. The results of the ecological risk assessment indicated that Site FT-20 (soil)
is not an area of potential ecological concern because of the lack of suitable habitat for
environmental receptors. However, petroleum hydrocarbons were detected in surface samples at
this site.
Site FT-20 (soil) was recommended for NFA in the OU 3 FS. The technologies incorporated in
Alternatives 8 (SVE) and 9 (Bioventing) were screened out as not applicable at Site FT-20 (soil)
because they are not considered effective for shallow soils. Based on an evaluation of the
concentrations of petroleum hydrocarbons and metals detected at the site, the RPMs have
determined that the constituents would not pose a threat to groundwater. The detected levels of
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hydrocarbons are less than the remediation goals for TPH/VOC sites (Figure 9). Therefore, the
implementation of Alternative 6 (No Action with Monitoring) or Alternative 7
(Removal/Disposal) are not considered cost-effective for Site FT-20 (soil), and NFA was the
selected remedy.
Site OT-51. PRO screening in accordance with the methodology presented in the OU 3 RI
indicated that detailed human health risk analysis was not required. The results of the ecological
risk assessment indicated that Site OT-51/SS-59 is not an area of potential ecological concern
because of the lack of suitable habitat for environmental receptors. However, the initial
evaluation criteria (based on the LUFT Manual; see Section 2.6.1) for TPH and BTEX were
exceeded in soils at the site. Because this site is unique among the TPH/VOC sites in that TPH
and VOC constituents were detected in both soil and groundwater, potential remediation in the
soil and groundwater are addressed separately as discussed in the sections below.
SoiL Site SS-59 was recommended for NFA in the OU 3 FS. The technologies
incorporated in Alternatives 8 (SVE) and 9 (Bioventing) were screened out as not
applicable at Site SS-59 because they are not considered effective for shallow soils.
Based on an evaluation of the limited distribution of detected petroleum hydrocarbons at
the site, the RPMs have determined that the constituents would not pose a threat to
groundwater. Therefore, the implementation of Alternative 6 (No Action with
Monitoring) or Alternative 7 (Removal/Disposal) are not considered cost-effective for
Site SS-59, and NFA was recommended.
In order to satisfy the RAOs for preventing human exposure to contaminated soils, to
reduce concentrations of contaminants to meet remediation goals, and to reduce the TMV
of contaminants, Alternative 9 (Bioventing) is recommended for Site OT-51. Alternative
6 (No Action) is not capable of satisfying the RAOs. The technologies incorporated in
Alternative 7 (Removal/Disposal) were screened out as not applicable for this site
because of the prohibitive costs associated with the volumes of deep soil that would be
required to be removed. The technologies incorporated for Alternative 8 (SVE) were
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screened out as not applicable for Site OT-51 because, although SVE encourages
biodegradation of TPH constituents, it is less effective and more costly than bioventing.
Therefore, Alternative 9 (Bioventing) was the selected remedy for Site OT-51. The
bioventing system has been installed as discussed in Section 2.9. The system became
operational in April 1996 and it is anticipated that remedy completion will be achieved
within 5 years.
Groundwater. In order to satisfy the RAOs for reducing dissolved contaminants in
groundwater to below MCLs, natural attenuation is the selected remedy for the
groundwater at Site OT-51. Although Alternative 10 (No Action) will ultimately satisfy
the RAOs, it does not ensure that groundwater will not be used for domestic purposes in
the future. As part of natural attenuation institutional controls, continued groundwater
monitoring would be performed to assess potential future migration and degradation of
COPCs in the groundwater. Land use restrictions would prohibit domestic use of the
groundwater and ensure protection of human health and the environment. If the levels of
COPCs observed in the downgradient monitoring wells do not decrease to meet
groundwater numerical cleanup standards (Table 13) within a sufficient time frame,
oxygenation of the top portion of the groundwater using oxygen-releasing chemicals
(Alternative 11) would be implemented to accelerate natural degradation.
2.6.4.2 Detailed Description of the TPH/VOC Site Preferred Alternatives. The
selected alternatives from the OU 3 FS for the TPH/VOC sites (identified in Section 2.6.4.1) are
described in detail below.
Site ET-Wc. Alternative 8 has been selected for this site and soil will be treated with SVE. This
includes the following specific activities:
• installation of an SVE system including extraction vents, monitoring points, air
blower, abovcground piping, equipment pad, and associated appurtenances;
• implementation of a soil vapor off-gas monitoring program to assess system
performance;
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• implementation of access restrictions to prevent unauthorized access to installed
equipment;
• implementation of land use restrictions which will restrict construction activities
that would impair the integrity of the existing system (i.e., SVE and monitoring
wells) while it is in place and prevent installation of monitoring or injection wells
in the site area (except where required for environmental purposes); these would
be enforced until the soil remedy is completed (groundwater restrictions are
covered under the OU 1 ROD [Montgomery Watson, 1994]);
• collection of confirmation samples (soil and vapor) to assess remedy completion;
and
• 5-year site review to assess the effectiveness of the remedy.
Sites WP-17, FT-19a, and OT-51 (soil). Alternative 9 has been selected for these sites and soils
will be treated with bioventing. This includes the following specific activities:
• installation of bioventing systems including injection vents, monitoring points, air
blower, aboveground piping, equipment pad, and associated appurtenances;
• implementation of a soil vapor monitoring program to assess system performance;
• implementation of long-term groundwater monitoring in accordance with an
approved basewide long-term groundwater monitoring plan;
• implementation of access restrictions to prevent unauthorized access to installed
equipment;
• implementation of land use restrictions which will restrict construction activities
that would impair the integrity of the existing system (i.e., bioventing, SVE, anJ
monitoring wells) while it is in place and prevent installation of monitoring or
injection wells in the. site area (except where required for environmental
purposes); these would be enforced until the soil remedy is completed;
• collection of confirmation samples (soil and vapor) to assess remedy completion;
and
• 5-year site review to assess the effectiveness of the remedy.
Site OT-51 (groundwater). Natural attenuation has been selected as the remedy for this site.
As a contingency, Alternative 11 would be implemented such that groundwater would be treated
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with oxygenation of the groundwater using oxygen-releasing chemicals if COPCs observed in
downgradient monitoring wells do not decrease to meet groundwater numerical cleanup
standards (Table 13) within a sufficient time frame. This remedy includes the following specific
activities:
decommissioning the abandoned well casing downgradient of Site OT-51;
implementation of long-term groundwater monitoring in accordance with an
approved basewide long-term groundwater monitoring plan;
implementation of use restrictions which would prohibit domestic use of the
groundwater,
installation of one or two downgradient monitoring wells to satisfy long-term
monitoring requirement (the OU 3 FS cost estimate included well installation for
the soils alternative presented on Table 20);
implementation of oxygen-releasing chemicals (Alternative 11) as a contingency
if COPCs in groundwater do not decrease to groundwater numerical cleanup
standards within a sufficient time frame (see Section 2.6.2.5); and
5-year site review to assess the effectiveness of the remedy.
2.6.43 Cost Analysis. A preliminary cost estimate was prepared for the selected
alternatives for each TPH/VOC site as part of the OU 3 FS process. Tables 17 through 21
summarize the cost analysis for the selected alternative for sites WP-17, FT-19a, FT-19c, OT-51
(soil and groundwater [assuming the use of ORC®]). With the selection of NFA for Sites FT-
19b, FT-20 (soil), and SS-59, there would be no additional costs incurred for these sites.
2.6.4.4 System Implementation. In an effort to accelerate the remedial process, early
remedial actions have been initiated, under the direction of the USAF, at the TPH/VOC sites
presented in this ROD. These accelerated actions were conducted to minimize present and future
environmental risks and were performed in agreement with the RPMs including the USEPA.
DTSC, Lahontan RWQCB, and USAF. The accelerated actions were performed at TPH/VOC
Sites WP-17, FT-19a, FT-19c, and OT-51 as summarized in Section 2.6.4.3 and detailed in the
Work Plan for Remedial Activities at the TPH/VOC sites (Montgomery Watson, 1995a).
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Bioventing systems were installed at WP-17, FT-19a, and OT-51 from December 1995 through
April 1996. These systems are currently in operation. An SVE system was installed at Site FT-
19c from December 1995 through March 1996 and is currently in operation. These actions are
summarized in Section 2.9 (Current Site Status).
2.6.5
Statutory Determinations for the TPH/VOC Sites
The selected remedies satisfy the statutory requirements of Section 121 of CERCLA, as amended
by SARA, in that the following five mandates are attained:
• The selected remedies are protective of human health and the environment, will
decrease site risks, and will not create short-term risk nor have cross-media
consequences.
* The selected remedies comply with federal and state requirements that are
applicable or relevant and appropriate to the remedial action such as chemical-
specific ARARs, chemical-specific clean-up standards, and action-specific
ARARs.
• The selected remedies are cost-effective in their fulfillment of the nine CERCLA
evaluation criteria through remediation of the TPH/VOC sites in a reasonable
period of time.
• The selected remedies utilize permanent solutions and alternative treatment
technologies or resource recovery technologies, to the maximum extent practical.
• The selected remedies satisfy the preference for treatment as a principle element.
2.6.5.1 Protection of Human Health and the Environment Protection of human
health and the environment at the OU 3 TPH/VOC sites is achieved by the selected remedies for
each site by removal of the contamination through treatment (i.e., biodegradation and SVE).
2.6.5.2 Compliance with ARARs. All pertinent ARARs identified for the TPH/VOC
sites (Table 15) will be met by the selected remedies.
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2.6.5.3 Cost Effectiveness. The USEPA, the USAF, and the State of California believe
that the selected remedies fulfill the nine criteria of the NCP and provide overall effectiveness in
relation to their costs.
2.6.5.4 Utilization of Permanent Solution and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Possible. The selected remedy represents, to
the maximum extent to which permanent solutions and treatment technologies can be used, a
cost-effective manner for remediating the OU 3 TPH/VOC sites. The remedies selected provide
the best balance of long-term effectiveness and permanence; reduction of TMV through
treatment; short-term effectiveness; implementability and cost-effectiveness.
2.6.5.5 Preference for Treatment as a Principle Element. The preference for treatment
as the principle elements is satisfied to the extent practicable by the selected remedies.
Alternative 9 (Bioventing) at Sites WP-17, FT-19b. and OT-51 will remove and treat
contaminants in soils to below acceptable levels through biodegradation. Alternative 8 (SVE) at
FT- 19c will remove the primary COPC (TCE) from soils by physical transfer from soil to air and
discharging the TCE. The expected concentrations of TCE discharged to the air (less than 1
pound/day) do not require treatment. By selection of natural attenuation for groundwater at Site
OT-51, the COPCs will be treated through natural attenuation with contingent implementation of
oxygen-releasing chemicals (Alternative 11) if the levels of COPCs observed in the
downgradient monitoring wells do not decrease to meet groundwater numerical cleanup
standards (Table 13) within a sufficient time frame.
2.7 SITE OT-69 SUMMARY
This section summarizes the site characteristics, risk assessment results, descriptions of the
alternatives evaluated, alternatives comparison, and the selection of the final remedy for Site OT-
69.
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2.7.1 Summary of Site OT-69 Characteristics and Risk Assessment
Site OT-69 consists of the TCE and PCE groiindwater contamination that was detected in the
flightline and operations support facilities area. The site was investigated independently by IT
and results of the investigations are discussed in detail in the RI/FS for the OU 3 TCE/PCE
Study Area (IT, 1995a). Additional modeling for the groundwater in the northeast portion of the
flightline area was performed by Montgomery Watson (Montgomery Watson, 1996a). Figure 14
presents select affected wells that identify the five plumes that make up Site OT-69. The results
of the investigations are summarized below.
The TCE/PCE contamination in this area was first identified during the 1992 investigation of
aviation jet fuel (JP-4) contamination within OU 2. In 1993, the extent of the TCEi/PCE
groundwater contamination in the vicinity of the flight line and operational support facilities was
investigated by IT. The 1993 investigations determined that the Aquitard under the Upper
Aquifer would prevent contaminants from migrating to greater depths, and wells completed to
the base of the Upper Aquifer, or to the top of the Aquitard, contained no contaminants. The soil
and groundwater TCE/PCE contamination at well MW-49 was further delineated by IT in 1995.
The additional investigations performed to further characterize the extent of TCE and PCE
contamination in the vicinity of MW-49 included soil-gas, soil and groundwater sampling and
analysis, and installation of cluster monitoring wells (IT, 1995a).
The 1993 Site OT-69 RI performed by IT resulted in the following principal findings and
conclusions (IT, 1995a):
The highest concentration of TCE in groundwater (37.0 ug/L) was detected in
well MW-49 on the southern edge of the study area. TCE was detected above the
MCL of 5 ug/L in seven samples.
The TCE groundwater contamination in OU 3 occurs in several, small, isolated
plumes. The new wells placed limits on the extent of contamination detected
during the OU 2 investigation.
TCE and PCE were not detected in any of the 613 soil samples analyzed during
the JP-4 OU 2 RI, or the 115 soil samples analyzed during the 1993 TCE/PCE RI
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investigation. TCE was detected in only 4 of the 29 soil samples collected during
the MW-49 TCE investigation.
• Contaminant fate and transport indicated that the highest levels of TCE in OU 3
will attenuate to 5 ug/L in approximately 40 to 45 years by physical mechanisms.
• PCE groundwater contamination (highest concentration was 7.8 pg/L) occurs in
one area near the southwest end of the flight line.
• Analysis of groundwater samples from cluster wells indicated that the TCE
groundwater contamination was limited to the upper 30 feet of the aquifer. In the
middle and bottom portions of the aquifer, no TCE was detected.
• The total volume of TCE and PCE dissolved within the groundwater was
calculated in the OU 3 TCE/PCE draft RI/FS to be approximately 0.8 gallons of
TCE and 0.006 gallons of PCE.
Subsequent to the 1992 OU 2 RI and 1993 RI (for Site OT-69), it was determined that additional
data was required to evaluate the extent of TCE/PCE at Site OT-69. The primary objective was
to further characterize the extent of TCE/PCE in the vicinity of well MW-49. The 1995 RI/FS
for the TCE/PCE study area (Site OT-69) resulted in the following principal findings and
conclusions (IT, 1995a):
The highest concentrations of TCE contamination (78 ug/L) occur in the top 6 feet
of the water table. The TCE concentrations drop to 4 ug/L, 6 feet below the water
table, and are non-detect 30 feet and deeper below the water table.
• TCE contamination in the vadose zone soils is lower than the level in the
groundwater. The concentration of TCE in soil-gas is below the equilibrium
concentration for the associated groundwater contaminant level. Therefore, the
vadose zone contamination does not pose a source for further groundwater
contamination.
• The TCE concentrations have declined in well MW-49 and increased in MW-60,
suggesting the plume has moved downgradient during the previous 2 years.
• Soil-gas and soil sample analysis indicated that MW-49/MW-72 are closer to the
source than the wash rack (see IT, 1995a).
• Fate and transport modeling indicates that the TCE contaminant plume in MW-49
area will reduce to 5 ug/L within 46 years and move approximately 1,000 feet
north from the original location. The other plumes will attenuate to the MCL in
much less time.
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Contaminant dispersion modeling suggest that the TCE plume will degrade to the
detection level and before being intercepted by the OU 1 groundwater treatment
system.
Groundwater sampling of wells NZ-51, NZ-52, NZ-54, and NZ-68 near the STP percolation
ponds has indicated the presence of TCE in the groundwater in the northeast flightline area. This
area is now considered part of Site OT-69; however, it was not specifically addressed in the
RI/FS for the TCE/PCE Study Area (IT, 1995a). Therefore, Montgomery Watson performed
additional solute-transport modeling of this area to assess the natural attenuation of the
"northeast" OT-69 plume.
The results of the additional modeling for the northeast OT-69 plume showed the current
northeastward migration of TCE at the northeast OT-69 plume will be changed significantly by
percolation resulting from the OU 1 treatment system. Modeling suggests the plume will move
south and east after commencement of effluent percolation from this system, and concentrations
are predicted to drop below the current MCL for TCE (5 ug/L) in less than two years.
There are currently no complete exposure pathways for the contaminated groundwater at: Site
OT-69. Groundwater in the site areas is not used as a source of domestic, industrial, or
agricultural supply. Therefore, there is currently no danger of adverse exposure to either base
personnel or residents. In addition, the groundwater does not reach the ground surface within the
base boundaries; therefore, there is no known exposure pathway to ecological receptors.
However, a risk assessment was performed that considered the possibility that the groundwater
within the study area would migrate beyond the boundaries of the base or that the base would be
used for residential development in the future (FT, 1995a). The risk assessment found there were
no likely exposure pathways and consequently no risks to the on-base workers and off-base
residents from TGE/PCE contamination. The total carcinogenic risk from dichloroetlhane
(DCA), TCE, and PCE based on three groundwater exposure pathways (drinking water; dermal
contact, and inhalation) is 2E-05 for a basewide residential development case and 3E-08 for a
limited residential development case.
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2.7.2 Description of Site OT-69 Alternatives
Based on the results of remedial investigations, it was determined that remedial action
alternatives be assessed at Site OT-69. An FS analysis was performed for this site as described
for the landfill sites in Section 2.5.2. Part of the FS process included development of RAOs as
described below.
There are currently no complete exposure pathways for the contaminated groundwater at Site
OT-69. Groundwater in the site areas is not used as a source of domestic, industrial, or
agricultural supply. Therefore, there is currently no danger of adverse exposure to either base
personnel or residents. In addition, the groundwater does not reach the ground surface within the
base boundaries; therefore, there is no known exposure pathway to ecological receptors.
However, in accordance with ARARs that call for protection of groundwater resources.
groundwater at Site OT-51 should be protected. Therefore, the RAO for groundwater is as
follows:
• Reduce the dissolved concentrations for identified COPCs in the groundwater at
Site OT-69 so that the most stringent concentrations identified in the ARARs are
not exceeded (MCLs, secondary MCLs, or quantifiable taste or odor criteria).
The groundwater numerical cleanup standards for Site OT-69 are presented on Table 13.
Six alternatives were developed for Site OT-69 as detailed in the RI/FS for the TCE/PCE Study
Area (IT, I995a). The alternatives, with their components, are as follows:
Alternative G-l
1) No Action
Alternative G-2
1) Land Use Restrictions
2) Deed Restrictions
3) Natural Attenuation with Groundwater Monitoring
Alternative G-3
1) In Situ Air Sparging
2) SVE Recovery/Abatement
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3) Groundwater Monitoring
4) Institutional Controls
Alternative G-4
1) Groundwater Extraction
2) Surface Groundwater Treatment with Ultraviolet (UV) Oxidation
3) Reinjection of Treated Groundwater
4) Institutional Controls
Alternative G-5
1) Groundwater Extraction
2) Surface Groundwater Treatment with granular activated carbon (GAC)
3) Reinjection of Treated Groundwater
4) Institutional Controls
Alternative G-6
1) Groundwater Extraction
2) Surface Groundwater Treatment with Thermally Abated Air Stripping
3) Reinjection of Treated Groundwater
4) Institutional Controls
2,7.2.1 Alternative G-l: No Action. Alternative G-l serves as a baseline against which
other soil alternatives are compared. No institutional controls or remedial action would be
undertaken. Natural attenuation of groundwater contamination would be allowed to continue.
All monitoring would be discontinued.
2.7.23 Alternative G-2: Natural Attenuation/Institutional Controls. Alternative G-2
consists of natural attenuation with institutional controls which include land use restrictions
prohibiting installation of wells for domestic purposes in the affected aquifer and deed
restrictions prohibiting use of contaminated water. In addition, continued monitoring of the
natural attenuation of the plume would be achieved through annual groundwater monitoring of
approximately 10 wells.
2.7.23 Alternative G-3: In Situ Air Sparging, SVE Recovery/Abatement in Vadose
Zone, Groundwater Monitoring. Alternative G-3 includes installation of approximate 58
sparge wells at isolated detection points. Air injection at each well would occur at 25 cubic feet
per minute (cfm) into the bottom 10 feet of the Upper Aquifer. Approximately 183 SVE vents
would be used to capture VOCs transferred from the liquid to vapor phase (assuming a radius of
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influence of 50 feet). Vapor abatement from SVB system would be accomplished using a
catalytic thermal oxidation system or an internal combustion engine (to be determined based on
the results of pilot tests).
2.7.2.4 Alternative G-4: Groundwater Extraction, Surface Groundwater Treatment
with UV-Oxidation, Reinjection of Treated Groundwater. Alternative G-4 includes
installation of approximately 21 extraction wells at isolated detection points. Extraction wells
would be pumped at an average rate of 25 gpm (totaling 525 gpm). Extracted groundwater
would be pumped to a central surface treatment plant where contaminants would be removed
using aqueous enhanced UV-oxidation. Approximately 225 gpm of treated groundwater would
be reinjected directly to the Upper Aquifer using nine injection wells located around the
perimeter of isolated detection points. Because of hydraulic limitations, the remaining 300 gpm
of treated groundwater would be discharged to the surface.
2.7JL5 Alternative G-5: Groundwater Extraction, Surface Groundwater Treatment
with GAC, Reinjection of Treated Groundwater. Alternative G-5 is the same as G-4 with the
exception that contaminants would be removed from the groundwater with GAC (rather than
UV-oxidation).
2.7.2.6 Alternative G-6: Groundwater Extraction, Surface Groundwater Treatment
with Thermally Abated Air Stripping, Reinjection of Treated Groundwater. Alternative G-
6 is die same as Alternatives G-4 and G-5 with the exception that contaminants would be
removed from the groundwater with an air stripper with a thennal fuel-assisted combustor for
vapor abatement (rather than UV-oxidation or GAC).
2.7.3 Summary of Comparative Analysis of Alternatives for Site OT-69
The remedial alternatives developed for Site OT-69 were analyzed in detail using the nine
evaluation criteria required by the NCP as detailed in Section 2.5.3 for the landfill sites.
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The resulting strengths and weaknesses of the alternatives were then weighed to identify the
alternative providing the best balance among the nine criteria. Table 22 summarizes this
comparison.
2.7.3.1 Overall Protection of Human Health and the Environment This criterion was
defined in Section 2.5.3.1 for the landfill sites. The comparative analysis for this criterion for
Site OT-69 is presented below.
Alternative G-l: Would reduce concentrations of contamination to levels affording acceptable
risk levels in approximately 46 years. There are currently no exposure pathways that would
result in a threat to human health. Given future land use plans, completed exposure pathways are
not anticipated in this time frame.
Alternative G-2: Would reduce concentrations of contamination to levels affording acceptable
risk levels in approximately 46 years. There arc currently no exposure pathways that would
result in a threat to human health. Given future land use plans, completed exposure pathways are
not anticipated in this time frame. In addition, land use and deed restrictions provide protection
of human health.
Alternative G-3: Would reduce concentrations of contamination to acceptable levels in
approximately 1 year. Potential additional risk introduced through the transfer of COPCs to the
air would be reduced to acceptable levels through treatment via catalytic thermal oxidation
system. A potential residual risk remains associated with off-site disposal of SVE condensate;
therefore, proper disposal is required.
Alternative G-4: Would reduce contaminated groundwatcr to acceptable levels in
approximately 10 years.
Alternative G-5: Would reduce contaminated groundwater to acceptable levels in
approximately 10 years. Potential residual risk remains associated with off-site disposal of spent
GAC; therefore, proper disposal is required.
*
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Alternative G-6: Would reduce contaminated groundwater to acceptable levels in
approximately 10 years. Potential additional risk introduced through the transfer of COPCs to
the air would be reduced to acceptable levels through treatment via a thermal fuel-assisted
combustor. Potential residual risk remains associated with off-site disposal of spent acid from
stripping tower wash down; therefore, proper disposal is required.
2.7.3.2 Compliance with ARARs. The definition of ARARs and this criterion was
presented in Section 2.5.3.2 for the landfill sites. A listing of federal and state laws and
regulations that are ARARs for the OU 3 TPH/VOC sites is provided in Table 15. These are also
the ARARs for Site OT-69. ARARs are expected to be met with all alternatives. Chemical-
specific ARARs will be met by ultimately achieving the cleanup standards. Action-specific
ARARs will be met by appropriate design and implementation of remedial alternatives.
2.7.3.3 Long-Term Effectiveness and Permanence. This criterion was defined in
Section 2.5.3.3 for the landfill sites. The comparative analysis for this criterion for Site OT-69 is
presented below.
Alternative G-l: Natural attenuation is expected to reduce risk to acceptable levels. Controls
for on-site residuals are not required.
Alternative G-2: Natural attenuation is expected to reduce risk to acceptable levels. Controls
for on-site residuals are not required.
Alternative G-3: Remediation through air sparging and SVE is expected to reduce risk to
acceptable levelsr Potential residual risk remains associated with off-site disposal of SVE
condensate; therefore, proper disposal is required. Controls for on-site residuals are not required.
Alternative G-4: Remediation groundwater extraction and surface treatment is expected to
reduce risk to acceptable levels. Controls for on-site residuals are not required.
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Alternative G-5: Remediation groundwater extraction and surface treatment is expected to
reduce risk to acceptable levels. Potential residual risk remains associated with off-site disposal
of spent GAC; therefore, proper disposal is required. Controls for on-site residuals are not
required.
Alternative G-6: Remediation groundwater extraction and surface treatment is expected to
reduce risk to acceptable levels. Potential residual risk remains associated with off-site disposal
of spent acid from stripping tower wash down; therefore, proper disposal is required. Controls
for on-site residuals are not required.
2.7.3.4 Reduction of Toxicity, Mobility, and Volume through Treatment. This
criterion was defined in Section 2.5.3.4 for the landfill sites. The comparative analysis for this
criterion for Site OT-69 is presented below.
Alternative G-l: Toxicity and mobility is not reduced. However, concentrations of
contaminants are reduced to levels detennined to be protective of human health. In addition, the
volume of affected groundwater is not reduced; however, the volume of groundwater with
concentrations of contaminants resulting in excess risk is ultimately reduced to zero.
Alternative G-2: Same as Alternative G-l.
Alternative G-3: A high degree of TMV reduction is achieved because contaminants are
destroyed on site through SVE abatement (catalytic thermal oxidation system or an internal
combustion engine).
Alternative G-4: A high degree of TMV reduction is achieved because contaminants are
destroyed on site through UV-oxidation.
Alternative G-5: A high degree of TMV reduction is achieved locally because contaminants are
removed from groundwater with GAC. Some chemical toxicity is transferred to an off-site
location with spent GAC.
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Alternative G-«: A high degree of TMV reduction is achieved locally because contaminants are
destroyed on site through thermal abatement. Some chemical toxicity is transferred to an off-site
location with spent acid wash.
2.7J.5 Short-Term Effectiveness. This criterion was defined in Section 2.5.3.5 for the
landfill sites. The comparative analysis for this criterion for Site OT-69 is presented below.
Alternative G-l: Under current or expected base land use, there are no completed exposure
pathways. However, in the event land use changes such that exposure pathways are completed,
this alternative would not eliminate exposure pathway reduction of concentrations to below
MCLs for 46 years. Because there is no remedial action taken, there is not potential exposure to
remedial workers.
Alternative G-2: Under current or expected base land use, there are no completed exposure
pathways. In addition, this alternative prevents the completion of exposure pathways in the
future by implementing institutional controls. There is possible exposure to remedial workers
during groundwater sampling which can be mitigated by following appropriate health and safety
procedures.
Alternative G-3: This alternative prevents the completion of exposure pathways in the future by
implementing institutional controls. A small potential risk to the community is generated by
transfer of contaminants to the vapor phase which is partially mitigated through SVE vapor
abatement/recovery. A relatively small short-term risk exists with the transport and disposal of
SVE condensate. There is possible exposure to remedial workers during monitoring activities
which can be mitigated by following appropriate health and safety procedures.
Alternative G-4: In addition, this alternative prevents the completion of exposure pathways in
the future by implementing institutional controls. There is possible exposure to remedial
workers during monitoring activities which can be mitigated by following appropriate health and
safety procedures.
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Alternative G-5: In addition, this alternative prevents the completion of exposure pathways in
the future by implementing institutional controls. A relatively small short-term risk exists with
the transport and disposal of spent GAC. There is possible exposure to remedial workers during
monitoring activities which can be mitigated by following appropriate health and safety
procedures.
Alternative G-6: In addition, this alternative prevents the completion of exposure pathways in
the future by implementing institutional controls. A small potential risk the community is
generated by transfer of contaminants to the vapor phase which is partially mitigated through
vapor abatement. A relatively small short-term risk exists with the transport and disposal of
spent acid wash water. There is possible exposure to remedial workers during monitoring
activities which can be mitigated by following appropriate health and safety procedures.
2.7.3.6 Implementability. This criterion was defined in Section 2.5.3.6 for the landfill
sites. The comparative analysis for this criterion for Site OT-69 is presented below.
Alternative G-l: No remedial action is undertaken for this alternative; therefore, there arc no
technical or administrative limitations and no services or materials are required.
Alternative G-2: There are no technical or administrative limitations for this alternative.
Services and materials required for groundwater monitoring arc readily available.
Alternative G-3: The technologies that make up this alternative arc technically implememtable,
proven, and available. Permitting may be required for off-site disposal of SVE condcnsate.
Services and materials required are readily available; however, significant amounts of
supplemental fuel would be required for SVE abatement system.
Alternative G-4: The technologies that make up this alternative are technically implementable,
proven, and available. Services and materials required are readily available.
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Alternative G-S: The technologies that make up this alternative are technically implementable,
proven, and available. Permitting may be required for off-site disposal of spent GAC. Services
and materials required are readily available.
Alternative G-6: The technologies that make up this alternative are technically implementable,
proven, and available. Permitting may be required for off-site disposal of spent acid wash water.
Services and materials required are readily available; however, significant amounts of
supplemental fuel would be required for vapor abatement system.
2.7.3.7 Cost This criterion was defined in Section 2.5.3.7 for the landfill sites. The
comparative analysis for this criterion for Site OT-69 is summarized in Table 23. Costs are
presented on a present-worth basis over a period of 30 years, with a discount rate of 7 percent. A
detailed cost analysis is presented in the RI/FS for the TCE/PCE Study Area (IT, 1995a).
2.7.3.8 State Acceptance. This criterion was defined in Section 2.5.3.8 for the landfill
sites. The comparative analysis for this criterion for Site OT-69 is presented below.
Alternative G-l: It is not likely the state would accept this alternative because it does not assure
prevention of exposure in the event future land use plans change.
Alternative G-2: It is likely the state would accept this alternative because it assures protection
of human health through periodic monitoring and deed restrictions. The Lahontan RWQCB has
accepted this alternative provided the assessment of other more active remedies is considered as
a contingency if the natural attenuation remedy is not restoring water quality in a timely manner.
Alternative G-3: It is likely that this alternative would be perceived favorably because of the
short duration of the remedial action (approximately 1 year). There may be objections to the
perception that there would be air emissions caused by this alternative; however, these would be
mitigated by proper abatement. There may also be objection to the production of residual waste
(SVE condensate).
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Alternative G-4: It is likely the state would accept this alternative because it assures protection
of human health through periodic monitoring, deed restrictions, and ultimate reduction of
contaminants to acceptable levels (in approximately 10 years).
Alternative G-5: It is likely the state would accept this alternative because it assures protection
of human health through periodic monitoring, deed restrictions, and ultimate reduction of
contaminants to acceptable levels (in approximately 10 years). There may be objection to the
production of residual waste (spent GAC).
Alternative G-6: It is likely the state would look favorably at this alternative because it assures
protection of human health through periodic monitoring, deed restrictions, and ultimate reduction
. of contaminants to acceptable levels (in approximately 10 years). There may be objections to the
perception that there would be air emissions caused by this alternative; however, these would be
mitigated by proper abatement. There may also be objection to the production of residual waste
(spent acid wash).
2.7.3.9 Community Acceptance. As defined in Section 2.5.3.9 for the landfill sites.
Community acceptance indicates the public support for a given alternative. Section 3.0 of this
ROD documents the community acceptance of the selected remedies, as presented in the
Proposed Plan (Montgomery Watson, 1997b). Section 3.0 includes a responsiveness summary
that addresses the comments received during the public comment period. The community did
not express any significant objections to the selected remedies during the public meeting or
public comment period.
2.7.4 The Selected Remedy for Site OT-69
This section provides a description of the preferred alternative for Site OT-69 based on the
detailed evaluation of alternatives presented in the RI/FS for the TCE/PCE Study Area (IT,
I995a). This section includes the basis for selection of a preferred alternative, a description of
the preferred alternative, and cost analyses.
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2.7.4.1 Selection of the Preferred Alternative. The RAOs established for Site OT-69
are presented in Section 2.7.2. The preferred alternative that best meets these objectives for Site
OT-69 based on the comparative analysis of the alternatives with respect to the nine CERCLA
criteria is Alternative G-2 (Institutional Controls/Natural Attenuation). This alternative assures
protection of human health and the environment through institutional controls, is effective at
ultimately reducing contaminant concentrations to acceptable levels though natural attenuation,
is very easy to implement, and is cost effective.
2,7.4.2 Detailed Description of the Site OT-69 Preferred Alternative. Alternative G-2
consists of natural attenuation with institutional controls which include land use restrictions
prohibiting installation of wells for domestic purposes in the affected aquifer and deed
restrictions prohibiting use of contaminated water. Continued monitoring of the natural
attenuation of the plume will be achieved through an approved long term groundwater
monitoring plan. More active remedies would be considered as a contingency if- the natural
attenuation remedy is not restoring water quality in a timely manner. The criteria under which
active remediation would be initiated at Site OT-69 were detailed in a memorandum prepared by
IT which is included as Appendix B to this ROD (IT, 1995b). Details regarding the criteria
established in this memorandum are summarized in Section 2.9.2.5. If it is determined that
natural attenuation is not restoring water quality, more active remedies would be assessed as part
of the 5-year review process and may include alternatives assessed as part of this ROD or
additional new technologies that may become available.
2.7.43 Cost Analysis. A preliminary cost estimate was prepared for the selected
alternative for Site OT-69 as part of the OU 3 FS process. Table 24 summarizes the cost analysis
for Site OT-69.
2.7.5 Statutory Determinations for Site OT-69
The selected remedy satisfies the statutory requirements of Section 121 of CERCLA, as amended
by SARA, in that the following mandates are attained:
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• The selected remedy is protective of human health and the environment, will
decrease site risks, and will not create short-term risk nor have cross-media
consequences;
• The selected remedy complies with federal and state requirements that are
applicable or relevant and appropriate to the remedial action such as chemical-
specific ARARs, chemical-specific clean-up standards, and action-specific
ARARs;
• The selected remedy is cost-effective in its fulfillment of the nine CERCLA
evaluation criteria through remediation of Site OT-69 in a reasonable period of
time;
• The selected remedy utilizes permanent solutions and alternative treatment
technologies or resource recovery technologies, to the maximum extent practical;
The distribution of contaminants at Site OT-69 and prohibitive costs associated with treatment
alternatives, preclude a remedy in which contaminants could be treated effectively. Therefore,
the selected remedy does not satisfy the preference for treatment as a principle element.
2.7.5.1 Protection of Human Health and the Environment. There are currently no
complete exposure pathways for the contaminated groundwater at Site OT-69. Groundwater in
the site areas is not used as a source of domestic, industrial, or agricultural supply. Therefore,
there is currently no danger of adverse exposure to either base personnel or residents. In
addition, the groundwater does not reach the ground surface within the base boundaries;
therefore, there is no known exposure pathway to ecological receptors. Protection of human
health and the environment at Site OT-69 is achieved through the selected remedy by ultimately
achieving acceptable concentrations through natural attenuation.
2.7.5.2 Compliance with ARARs. All pertinent ARARs identified for Site OT-69
(Table IS) will be met by the selected remedy.
2.7.5.3 Cost Effectiveness. The USEPA, the USAF, and the State of California believe
that the selected remedy for Site OT-69 fulfills the nine criteria of the NCP and provides overall
effectiveness in relation to their costs.
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2.7.5.4 Utilization of Permanent Solution and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Possible. The selected remedy represents, to
the maximum extent to which permanent solutions and treatment technologies can be used, a
cost-effective manner for addressing Site OT-69. The alternative selected provides the best
balance of long-term effectiveness and permanence; reduction of TMV through natural
attenuation; short-term effectiveness; implementability; and cost-effectiveness.
2.7.5.5 Preference for Treatment as a Principle Element
The preferred alternative does not incorporate active treatment. However, concentrations of
contaminants are reduced to levels determined to be protective of human health. The volume of
affected groundwater is not reduced; however, the volume of groundwater with concentrations of
contaminants resulting in excess risk is ultimately reduced to zero.
2.8 DOCUMENTATION OF SIGNIFICANT CHANGES
There are no significant changes in this ROD from the OU 3 Proposed Plan.
2.9 CURRENT SITE STATUS
The preferred alternatives described in this ROD are based on meeting the RAOs identified
during the OU 3 FS process (Montgomery Watson, 1997a and IT, 1995a). The findings of the
final OU 3 FS Report and the accompanying OU 3 Proposed Plan (Montgomery Watson, 1997b)
were used to develop this ROD. The technical information supporting each alternative is
included in these reports and the OU 3 RI Report (Montgomery Watson, 1996a).
In an effort to accelerate the remedial process, to minimize present and future environmental
risks, to reduce potential impacts to groundwater, and to facilitate timely transfer of property to
the community, cleanup activities have been initiated under the direction of the USAF, at some
of the sites presented in this ROD. These accelerated actions were performed in agreement with
the RPMs including the USEPA, DTSC, Lahontan RWQCB, and USAF. This work has been
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performed under the FSRA contract with the Air Force Center for Environmental Excellence
(AFCEE). Accelerated actions performed to date have implemented the proposed cleanup
activities.
The detailed alternatives evaluation for these sites presented in the OU 3 FS was performed prior
to the initiation of the accelerated action; therefore, the FS alternatives comparison and cost
analysis are presented in the previous sections of this ROD in its original form. Table 25
presents the current estimates of present worth costs for the selected remedial alternatives
incorporating the actual construction costs incurred to date for sites where accelerated actions
were performed.
The accelerated actions performed to date are summarized in the sections below. The
effectiveness of these remedies will be assessed as part of the ongoing O&M and long-term
groundwater monitoring and will be the focus of the 5-year site review. As part of the 5-year
review, the status of compliance with ARARs will be evaluated and reported. The specific
action items to meet the requirements of this ROD are presented in Appendix A.
2.9.1 Landfill Sites
Accelerated actions were performed at landfill sites DP-03, DP-04, LF-12. LF-14, LF-44, and the
SEDA (nine sites). The actions at the landfill sites began in June 1996 and were completed in
April 1997. The preferred alternatives implemented for the landfills minimizes or mitigates the
human health and ecological risks presented on Table 2 by providing a physical barrier to
potential contamination. A description of the barrier and the accelerated activities performed at
the landfill sites are discussed below.
Z9.1.1 Sites DP-03 and DP-04. Grading the existing soil cover to promote surface
runoff and decrease infiltration of surface water into the refuse; installation of a 2-foot-thick
native soil cover to reduce the potential of exposure to contaminants; installation of site
perimeter fencing to control site access; installation of drainage ditches above the landfill to
prevent surface water from running onto the landfill sites; and re-establishment of native plant
•
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species on the graded surface. Prior to construction of the soil cover at Site DP-04, hot spot
removal was performed by removing approximately 10 cubic yards of soil to reduce potential
risk to burrowing animals. This soil was disposed off site.
2.9.1.2 Sites LF-12, LF-14, and the SEDA (Nine Sites). Removal of surface debris;
rehabilitation of the existing soil cover to produce a cover with an estimated thickness of 12 to 18
inches; grading or cutting of the surface to promote surface runoff and decrease infiltration of
surface water into the refuse; installation of drainage ditches above the landfill to prevent surface
water from running onto the landfill sites; installation of site perimeter fencing to control site
access; and re-establishment of native plant species on the graded surface.
2.9.1.3 Site LF-44. Contaminants of potential concern were not detected in soil samples.
Activities performed at this site included the removal of surface debris in September and October
1995. This debris was disposed of off site.
2.9.1.4 Groundwater Monitoring For the Landfill Areas. Regulations require
groundwater monitoring for each landfill site. Groundwater monitoring at the landfill sites is
being performed as presented in the Basewide Long-Term Groundwater Monitoring Plan for
GAFB and the Site Closeout Report for DP-03, DP-04, LF-12, LF-14, and the Southeast
Disposal Area (Montgomery Watson, 1996c, 1997c). Several rounds of groundwater monitoring
have been completed under this plan (Montgomery Watson, 1996d,e; 1997d).
As part of the monitoring program, monitoring wells associated with the landfills are sampled
and analyzed for halogenated volatile organic compounds (HVOCs) (EPA method 8260
suggested), and landfill indicator parameters (pH, total dissolved solids, chloride, sulfate, and
nitrate). The sampling frequency and analyte selection may be modified as the program
progresses.
Monitoring is used to assess whether contaminants have migrated into the environment. Water
Quality Protection Standards (WQPS) will be developed to assess whether there has been a
release from the landfills. The WQPS will be developed within 6 months of the signing of this
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ROD and will be based on the available groundwater data to establish baseline values for which
future sampling results will be compared.
2.9.1.5 Ecological Monitoring For the Landfill Areas. The landfill remediation
consisted of activities that would minimize exposure of landfill wastes to ecological receptors.
For example, landfill remediation consisted of the installation of a 12- to 24-inch native soil
cover as described above. During construction of the remedy, the native soil was compacted by
grading. Site access is controlled by fencing. The fence was installed to a depth of 1 foot bgs.
The sites were revegetated with native plants.
Although the soil was compacted during construction, the sites provide potential habitat for
burrowing animals that can burrow under or move through small openings in the fence.
Burrowing animals could potentially compromise the effectiveness of the cap as a barrier
between the waste and the surrounding ecosystem. Burrowing animals that could potentially
enter the area include special-status species such as the Mojave ground squirrel, Mojave vole,
desert tortoise, San Diego homed lizard, and burrowing owl. Other species that may impact the
soil cover include the coyote, badger, and kangaroo rat.
The soil covers at each site will be maintained by surveying for animal burrows. The Air Force
will consult with the State Department of Fish and Game to develop a burrows management
protocol for the O&M document. A contingency plan for recurring burrow problems and the
specific details of the ecological monitoring plan will be presented in the subsequent O&M
document.
The maintenance activity schedule is presented in the Site Closeout Report for DP-03, DP-04,
LF-12, LF-14, and the Southeast Disposal Area (Montgomery Watson, 1997c). The schedule to
implement any recommended repairs noted during the routine maintenance inspections will vary
depending on the type of repair. Minor repairs may be implemented in 30 days, but more
difficult or more costly repairs may require more time to implement. Implementation of
revegetative repairs will be limited by seasonal conditions relating to the plant's life cycle. An
effort will be made to make revegetative repairs as soon as it is practical based on seasonal
2-106
-------
timing. The subsequent routine maintenance inspection will note if the recommended repairs
were made.
2.9.2 TPH/VOC Sites
Accelerated actions at petroleum TPH/VOC sites were conducted to minimize present and future
environmental risks, reduce potential impacts to groundwater, and facilitate reuse as described
below. Access and land use will be restricted at all sites. These restrictions on site use will be
subject to re-evaluation as remediation efforts progress. It is anticipated that this land will be
used only for industrial purposes.
2.9.2.1 Sites WP-17, FT-19a, and OT-51 (Soil). Soil at these sites is currently being
treated with bioventing. The bioventing systems were installed from December 1995 through
April 1996 and are currently in operation.
2.9^2 Site FT-19b. Petroleum contamination at this site was evaluated in the OU 3 FS
Report and the site is recommended for NFA (Montgomery Watson, 1997a). Medical waste
found on the surface was removed and disposed off site. Downgradient monitoring will continue
to assess groundwater quality.
2.9.2.3 Site FT-19c. Soil at this site is currently being treated with SVE. The SVE
system was installed from December 1995 through March 1996 and is currently in operation.
2.9.2.4 Site OT-51 (Groundwater). The groundwater data collected since September
1995 at Site OT-51 as part of the long-term groundwater monitoring effort (Montgomery
Watson, 1996d,e,f; 1997d,e,f) have indicated that the COPCs in groundwater increased slightly
and then began decreasing. It is expected that the plume will be below detectable levels of
benzene in 5 years. If subsequent rounds of long-term monitoring do not continue to show the
trend of decreasing levels of COPCs. the contingent remedy of installation of oxygen-releasing
chemicals described for Alternative 11 (Section 2.6.2.6) will be implemented.
2-107
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2.9.ZS Site O1V69. The Lahontan RWQCB has accepted Alternative G-2 (Institutional
Controls/Natural Attenuation) provided the assessment of other more active remedies is
considered as a contingency if the natural attenuation remedy is not restoring water quality in a
timely manner. The criteria under which active remediation would be initiated at Site OT-69
were detailed in a memorandum prepared by IT which is included as Appendix B to this ROD
(FT. 1995b). The contents of this memorandum are summarized below.
The monitoring and response plan proposed by the USAF was developed based on computer
modeling simulations that estimate specific future concentrations in particular wells projecting
that water quality objectives will be restored in approximately 50 years. If the expected
reductions do not occur in the projected time frame, plus or minus 15% of the projected
concentration, then the data will be evaluated. If the data are less than two standard deviations of
the projected concentrations, then monitoring may continue. If the data are greater than two
standard deviations, then the wells will be resampled and the data reevaluated. If the data are
still greater than two standard deviations of the original projected concentrations, then an active
remedy consisting of air sparging with soil vapor extraction will be implemented or the agencies
will reach consensus regarding a technical decision for implementing some other appropriate
active remedy. The ROD will be amended at that time to specify the ARARs for the contingent
remedy.
As part of the remedy for Site OT-69, groundwater will be monitored and the data will be
evaluated. If measured TCE concentrations exceed the predicted ranges presented in Appendix
B, the following steps will be taken:
1) Determine the variability of the analytical method employed at the time of the
analysis.
2) Consider the analytical standard deviation and calculate the possible contaminant
concentration range.
3) Determine if the calculated range in concentration is two standard deviations
above the predicted concentration range.
2-108
-------
4) If the concentration is two standard deviations above the predicted concentration
range, initiate verification measures.
S) If the concentration is less than two standard deviations above the predicted
concentration range, maintain routine sampling schedule.
If it is determined that natural attenuation is not restoring water quality, more active remedies
would be assessed as part of the 5-year review process. If a more ac.tive remedy is determined to
be warranted, the USAF will make a timely request for funds by identifying to the Department of
the Air Force the funding needed to complete the activities in accordance with Executive Order
12088 and OMB circular A-106 (which is updated bi-monthly and for which funding requests are
made at least two years in advance when possible), or any pertinent amendments to these
requirements.
In the event that Congress fails to appropriate necessary funding for OU 3 ROD activities at
GAFB, the following will occur:
the USAF will so advise all FFA signatories within 90 days of such failure; and
the USAF will provide to all FFA signatories documentation of all measures it
will undertake to ensure that ROD activities are completed. These measures may
include, but are not limited to, continuing to seek funding for implementing the
contingent remedy.
2.9.2.6 System Monitoring of the TPH/VOC Sites. A vapor monitoring program for
the bioventing and SVE systems was developed based on field observations and on the results of
pilot testing before system startup. Field monitoring at the bioventing and SVE sites includes
routine system maintenance and monitoring of soil vapor to document reductions in petroleum
TPH/VOC concentrations and to determine the effectiveness of cleanup. At the bioventing sites,
soil gases (oxygen and carbon dioxide) are monitored because they can indicate changes in
biological activity. Increased biological activity is an indicator of biodegradation of the
hydrocarbon compounds. Soil vapor monitoring is conducted by collecting soil vapor from
monitoring points installed at various locations at the sites. Confirmation samples (soil and
2-109
-------
vapor) will be collected as necessary from the TPWVOC sites to confirm completion of the
remedy prior to closure of the sites.
2.9.2.7 Groundwater Monitoring For the TPH/VOC Sites. Groundwater monitoring
at applicable sites will be performed as presented in an approved long-term groundwater
monitoring plan for GAFB. Several rounds of groundwater monitoring have been completed
under this plan (Montgomery Watson, 1996d,e,f and 1997d,e,f). The sampling frequency and
analyte selection may be modified as the program progresses. The rationale for system shut
down will be provided in subsequent RD/RA documents.
2-110
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§
w
Section 3
MONTGOMERY WATSON
-------
-------
3.0 RESPONSIVENESS SUMMARY
3.1 OVERVIEW
The public comment period for the proposed plan began on September 22, 1997 and ended on
October 22, 1997. A public notice summarizing the OU 3 Proposed Plan, and announcing the
public comment period and public meeting was printed in the Daily Press in Victorville, the
Desert Dispatch in Barstow, and the Sun in San Bernardino at the start of the public comment
period. A press release was sent to five other local newspaper and radio organizations also
summarizing the OU 3 Proposed Plan and announcing the public comment period and the public
meeting.
The public meeting was held on October 8, 1997 at the Green Tree Inn, Victorville, California.
Representatives from USAF, DTSC, USEPA, and Lahontan RWQCB were present at the
meeting. No members of the community attended. During the public comment period, written
comments were received from the SCIA and the City of Victorville in a letter dated October 3,
1997.
Judging from the comments received, the community accepts the USAF's preferred remedial
alternatives for the 60 OU 3IRP sites.
3.2 BACKGROUND ON COMMUNITY INVOLVEMENT
The USAF values public input and has endeavored to maintain public involvement since the
beginning of the environmental investigation and cleanup activities at GAFB. A chronological
history of the community involvement with environmental issues at the GAFB is summarized
below.
In November 1987, GAFB provided information about environmental concerns at the base as
part of the "GAFB Community Days" activities. In 1988, a repository of information for public
review was established at the GAFB library. In early 1990, similar repositories were established
3-1
-------
at the Adelanto and Victorville public libraries. Administrative files for the project are
maintained at the GAFB AFBCA located in Building 321. In October 1992, GAFB held an
informational open house to discuss the environmental cleanup program and visit the potentially
contaminated sites.
In July 1991, GAFB established a TRC that consisted of members of the community and local
agencies and governments. The TRC met on a quarterly basis. In January 1994, GAFB
established the RAB which replaced the TRC. The RAB is designed to act as a focal point for
environmental information exchange between GAFB and the public. The RAB met quarterly
until 1997 when it voted to meet annually. The meetings are open to the public. An RAB and
community update meeting was held June 4, 1997, in Victorville, California.
33 SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC
COMMENT PERIOD
Comments received during the GAFB OU 3 public comment period on the final FS and Proposed
Plan are summarized below. The comment period was held from September 22, 1997 to October
22, 1997. The comments are presented in the order in which they were received and copies of
comments arc included as part of the administrative record (Appendix C).
PubUc Meeting: No comments were received during the public meeting.
Written Comments:
1. The SCIA and the City of Victorville issued a letter dated October 3, 1997 containing
comments as summarized below:
a) Concerned was expressed that the implementation of Alternative 4 (Soil Cover) to
Sites DP-03 and DP-04 would restrict future reuse of the land in this area.
Additionally, the question was asked as to what would be the cost associated with
remediating the sites such that future reuse would not be limited.
3-2
-------
b) The SC1A inquired as to whether the preferred alternative constituted cleanup for
Sites DP-03 and DP-04.
c) A request for clarification was made as to what is meant by the "preferred
alternative," what alternatives were evaluated other than the "preferred
alternative," and whether the preferred alternative is permanent.
Air Force Response: The response to these comments is as follows:
a) As part of the FS process (Montgomery Watson, 1997a), technologies were
evaluated and screened as to whether they would be appropriate for the landfill
sites. The only technology that would allow unrestricted reuse of Sites DP-03 and
DP-04 would be removal of all wastes and disposal at an off-site facility.
Removal and disposal of was "screened out" as a potential technology largely
because of the impracticality of the technology given the heterogeneity and
volume of the wastes. The general CERCLA experience has led to the
establishment of containment as the appropriate response for landfill sites. This
issue is discussed in additional detail in Sections 4.2 and 5.4 of the OU 3 FS
Report (Montgomery Watson, 1997a). Because removal and disposal was
screened out as a technology, it was not considered in the alternatives evaluation
phase of the FS process. Therefore, a detailed cost analysis was not performed for
this option. However, it is anticipated that removal and disposal of all wastes at
these sites would be cost prohibitive.
b) The preferred alternative would constitute cleanup of the sites and its selection
would be documented with the signing of this OU 3 ROD.
c) The term "preferred alternative" refers to the remedial option that is determined to
best meets the nine CERCLA criteria of 1) overall protection of human health and
the environment, 2) compliance with ARARs, 3) long-term effectiveness and
3-3
-------
permanence, 4) reduction of TMV through treatment, 5) short-term effectiveness,
6) implementability, 7) cost, 8) state/support agency acceptance, and 9)
community acceptance.
The preferred alternative selected for Sites DP-03 and DP-04 is Alternative 4 (Soil
Cover). However, five separate alternatives were evaluated for these sites. The
alternatives evaluated for these sites were as follows:
Alternative 1 (No Action with Monitoring)
Alternative 2 (Institutional Controls)
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)
Alternative 4 (Soil Cover)
Alternative 5 (Synthetic Cap)
The selection of the Alternative 4 for Sites DP-03 and DP-04 is considered to be
the most effective to minimize present and future environmental risks, reduce
potential impacts to groundwater, and facilitate timely transfer of the surrounding
property to the community. The implementation of the preferred alternative
would be the permanent solution pending 5-year review of monitoring activities
as required by CERCLA.
3-4
-------
REFERENCES
Boyle Engineering Corporation (Boyle), 1987. "Alter Base Water Supply/George Air Force
Base, Victorville, California. Well Field Analysis." San Bernardino, California.
CH2M Hill, 1982. "Installation Restoration Program Phase I Records Search for George Air
Force Base, California." Gainesville, Florida
CRSS Constructors, Inc., 1996. "Activation Plan for the Southern California International
Airport." Irvine, California. July 1996.
Hinchee, R.E., S.K. Ong, R.N. Miller, D.C. Downey, and R. Frandt, 1992. Test Plan and
Technical Protocol for a Field Treatability Test for Bioventing, Revision 2. Prepared for
the U.S. Air Force Center for Environmental Excellence, Brooks Air Force Base, Texas.
May 1992.
International Technologies Corporation (IT), 1991. "Community Relations Plan for the
Installation Restoration Program at George Air Force Base, California." San Bernardino,
California, April 1991.
IT, 1992. "Remedial Investigation, Operable Unit 2, JP-4 Spill, George Air Force Base,
California." San Bernardino, California, April 1991.
IT, 1995a. "Remedial Investigation Feasibility Study, OU 3 TCE/PCE Study Area, George Air
Force Base, California." San Bernardino, California. July 1995.
IT, 1995b. "Criteria for Active Site Remediation - OT-69," from Kandi Brown of IT to Denise
Caron of the AFBCA. November 6,1995.
James M. Montgomery, Consulting Engineers, Inc. (JMM), 1988. "Installation Restoration
Program, Phase FV-A Feasibility Study. Northeast Disposal Area, Upper Aquifer
Remediation. George Air Force Base, California." Pasadena, California, April 1988.
JMM, 1992. "Work Plan Addendum, Operable Unit 3, George Air Force Base, California."
Walnut Creek, California. August 1992.
Leaking Underground Fuel Tank (LUFT) Task Force, State of California, 1989. Leaking
Underground Fuel Tank Field Manual: Guidelines for Site Assessment, Cleanup, and
Underground Storage Tank Closure. October 1989.
LSA Associates. Inc. (LSA), 1989. "Biological Assessment of the Montgomery Engineers
Groundwater Contamination Remediation System." July 1989.
Metcalf & Eddy (M&E), 1994. "Remedial Investigation Summary Report for Soil Removal at
Miscellaneous OU 3 Sites. George Air Force Base, California." Redwood City,
California. June 1994. *
R-l
-------
REFERENCES
(Continued)
Montgomery Watson, 1994. "Record of Decision, Operable Unit 1, George Air Force Base
California." Walnut Creek, California. March 1994.
Montgomery Watson, 1995a. "Work Plan for Remedial Activities at Sites WP-17 FT-19a FT-
19b, FT-19c, OT-51 and the Oil/Water Separators, George Air Force Base, California "
Walnut Creek, California. August 1995.
Montgomery Watson 1995b. "Pre-Design Study, Operable Unit 1, George Air Force Base,
California." Walnut Creek, California. October 1995.
Montgomery Watson, 1995c. "Basewide Long-term Groundwater Monitoring Work Plan/Field
Sampling Plan, George Air Force Base. California." Walnut Creek, California. October
Montgomery Watson, 1996a. "Remedial Investigation Report, Operable Unit 3, George Air
Force Base, California." Walnut Creek, California. April 1996.
Montgomery Watson, 1996b. "Closure and Post-Closure Maintenance Plan for DP-03 DP-04
LF-12, LF-14, and the Southeast Disposal Area, Technical Plan, and Quality Program'
Plan, George Air Force Base, California." Walnut Creek, California. April 1996.
Montgomery Watson, 1996c. "Basewide Groundwater Monitoring Sampling and Analysis Plan,
George Air Force Base, California." Walnut Creek, California. September 1996.
Montgomery Watson. 1996d. "Basewide Long-Term Groundwater Monitoring Report
September 1995 Sampling Event, George Air Force Base, California." Walnut Creek
California. March 1996.
Montgomery Watson, 1996e. "Basewide Long-Tenn Groundwater Monitoring Report, January
1996 Sampling Event, George Air Force Base, California." Walnut Creek. California
August 1996.
Montgomery Watson, 1996f. "Basewide Long-Term Groundwater Monitoring Report. May
1996 Sampling Event, George Air Force Base, California." Walnut Creek, California
October 1996.
Montgomery Watson, 1997a. "Feasibility Study Report, Operable Unit 3, George Air Force
Base, California." Walnut Creek, California. February 1997.
Montgomery Watson, 1997b. "Proposed Plan for Operable Unit 3, George Air Force Base
California." Walnut Creek, California. September 1997.
R-2
-------
REFERENCES
(Continued)
Montgomery Watson, 1997c. "Site Closeout Report for DP-03, DP-04, LF-12, LF-14, and the
Southeast Disposal Area, George Air Force Base, California." Walnut Creek, California
June 1997.
Montgomery Watson, 1997d. "Basewide Long-Term Groundwater Monitoring Report, October
1996 Sampling Event, George Air Force Base, California." Walnut Creek, California
February 1997.
Montgomery Watson, 1997e. "Basewide Long-Term Groundwater Monitoring Report, February
1997 Sampling Event, George Air Force Base, California." Walnut Creek, California
June 1997.
Montgomery Watson, 1997f. "Basewide Long-Term Groundwater Monitoring Report, July 1997
Sampling Event, George Air Force Base, California." Walnut Creek, California. October
Norris, R. M., and R. W. Webb, 1990. Geology of California. Second Editinn John Wiley &
Sons, Inc., New York, New York.
Regional Water Quality Control Board (RWQCB), 1995. "A Compilation of Water Quality
Goals." RWQCB, Central Valley Region, Sacramento. California. July 1995.
Science Applications International Corporation (SAIC). 1987. "Installation Restoration Program
- Phase II - Stage 2 Confirmation/Quantification (Final Report), George Air Force Base.
California." Bellevue, Washington. January 8, 1987,
Thomas Bros. Maps, 1992. California Road Atlas and Driver's Guide. Irvine, California.
U.S. Air Force (USAF), 1989. "Closure of George Air Force Base, San Bernardino County.
California, Draft Environmental Impact Statement." December 1989.
USAF, 1992. "Environmental Impact Statement, Disposal and Reuse of George Air Force Base
California." March 1992.
USAF, 1993. "Management Action Plan (MAP), George Air Force Base, California." October
19, 1993.
U.S. Environmental Protection Agency (USEPA), 1988. Guidance for Conducting Remedial
Investigations and Feasibility Studies Under CERCLA. Interim Final. Office of
Emergency and Remedial Response, Washington, D.C., EPA/540/G-89/004, October
1988.
R-3
-------
REFERENCES
(Continued)
USEPA, 1989. Risk Assessment Guidance for Superfand. Vol. 1: Human Health Rvaluatinn
Manual, Part A, Region EX Recommendations, Office of Solid Waste and Emergency
Response, December 1989.
USEPA, 1990. A Guide to Developing Superfund Records of Decision. Office of Emergency
Response, Hazardous Site Control Division, Directive: 9335.3-02FS-1. May 1990.
U.S. Geological Survey (USGS), 1992. "Streamflow Reports for the Mojave River, 1905
through 1992." Published and unpublished records.
R-4
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I
Figures
MONTGOMERY WATSON
-------
-------
• $ SILVER
= MTN S
B*M \ ~ SPARKHULE
I ' MTN
Lucun* Valtay^.
SAN
BERNARDINO
MOUNTAINS
"""OrllE!. x. J
,,„•,, / MOUNTAINS \\
'*. '^
GEORGE AIR FORCE BASE
VICINITY MAP
SCALE IN MILES
Source: ModHod from Thoow Btot. Maps (1W2)
-------
vs( shewn.
WV, DT-4S OT-61. OT-6Z. WP-63. OT-64. OT-ffi. asd OT-6S;
2l SEDA S4ift «K4XJ9 LF-tt?. IP-PS, RW-OS,OfMO. W. (5.
-------
5 •Jox*>
XV, \
"•.. \ "•-%„ Ji
/ p \ cr " 'X v-«- A v- ->. v
/ \ ™>ntlll \ VS. -. %\
/A***.***^ $ "', X. \JohnmX V\
^£!ssi^ '•""'*" ^"-, ^
•%,„
"mi,,,
GEORGE AIR FORCE BASE
REGIONAL PHYSIOGRAPHY
Sowc*: MMMM tan Thexno Bnw. Map* (1932) ant Nonfc «l «l. (1880)
-------
He*p«ria
MOJAVE
BASIN —
• X
GulnBoundoy
SCALE IN MILES
0 5 10
LEGEND
Psrann!*! Bowing Stream
InMonlMnt Flowing Stream
— AppKcdmatiLocallonofQ«orgaGreun«atin
{SUMUifKB Surveys, 1990)
SOOfCfc 3MC.IM7
MUNIhUMUl WHTSON
MAJOR HYDROGEOLOGIC FEATURES
IN THE MOJAVE RIVER BASIN
FIGURE 4
-------
0 ^^P \
APPROXIMATE SCALE IN MILES
LEGEND
O Municipal W*W Supply MM
O Domestic Wat«r Supply Wrt
£ Surface Spring
/
Approximate Dirtction erf
Groundwatw Row in Upper
AquKtr
Approximata Oiraction of
Qroundwatar Bow in Lower
AquHw
w««« •!• «ppTOjdmimy locawd bisod on C«lltoini« O«p«mr>«ni wuer Rnourew rncord*
MONTMMBIY MMTSON
APPROXIMATE LOCATIONS OF
KNOWN MUNICIPAL AND
DOMESTIC WATER-SUPPLY WELLS,
QAFB VICINITY
FIGURE 5
-------
N
•-_. —Ti < . -^ , ^ • ,/
1 - !L i.-j .*. f '—•'•. '-
LEGEND
Q OU3STTE
OT-69 TCE PLUMES (OU 3)
SCALE W FEET
GEORGE AIR FORCE BASE
OPERABLE UNIT 3 FEASIBILITY STUDY
SITE LOCATIONS
Figure
6
-------
Existing Condition
Wastes)
Implementation of Surface Controls
Add Native Soil .
From •QH'Sit© 5
Areas
Remove Wastes From the S;
k Grade to * 5% Jvfcnimun
Result
, Rehabilitated Sod Cover
,. Revegstc
±^L *
K
W
-------
Alternative 4: Native Sofi Cover
24-«ich Thick Soil Cowef
X"
Revegetati
* V ~ *
Drainage Channel
Graded Surface
{Min. l.S% Slope)
Attcrnative 5: Synthetic Cap
24-inch Thick Soi! Cover
/
Drainage Channel
-Surface
(M?n. 1.5% Slope)
-------
id Surfs
10,000
TPH(«»g«oljnt) 1,000
Benzene t
Toluene 50
Elhytfaanzena so
Total Xytenw so
8
TPH (as dies*)
TPH(ugaaolrM)
Bwuen*
Toktww
EOtyltenzww
Total Xytonw
1.000
100
0.3
0.3
1
t
TPH(MOlM«0 100
TPH (at gasoline) 10
BarcniM 0.005
ToltMn* o.OOS
0.005
0.015
Water Tabl*
Nods:
Not to •ate
Unttt •/• mg*g (pprn)
Soure»: (LUFTTuk Face*. 1988)
GEORGE AIR FORCE BASE
REMEDIATION GOALS FOR SOILS
AT THE OU 3 TPH/VOC SITES
RGURE9
-------
g"
A
i
S"
k
p
TCE
1
k
.
s
7,50
TOE
k
?
//%M^
f&*
900
TCE 37S
TCE 100
I
TCE 30 j
1 k
| TCE 12.5
§
' b — — — — — •
t TCE 0.6 I
?> I... .. I
[ v_ _„ __y**??$*___. _
Nou*:
Not to teal*
Unte v* M»*0 (ppb)
Souic*, SESCML MixMIng «t nr-ISedMtad k> ttw OU 3 FS.
MONTCOMBIYWftTSON
GEORGE AIR FORCE BASE
REMEDIATION GOALS FOR TCE
IN SOILS AT SITE FT-19C
FIGURE 10
-------
Discharge to
Atmosphere
Flow
control
valva
Air-water
separator
Temperature
gauge
Blower
Air velocity
rotameter
Vacuum
gauge
1
AIR
EXTRACTION
WELL
Not*: Not to Scale
SCHEMATIC OF SVE
SYSTEM DESIGN
FIGURE 11
-------
Male
quick
connect
\.
Moisture
FemaJa
quick
connect
A
Sampling
pump
^-^&-
Analyzer
'Soil vapor monitoring point
Not to Scale
Modilitd from Hnctwt. H. (1.1992.
MONTGOMDmHKTSON
SCHEMATIC DIAGRAM OF
SOIL VAPOR SAMPUNG FROM
MONITORING POINT
FIGURE 12
-------
Air from
Atmosphere
Vacuum gauge
Flow
control
valve
Temperature
gauge
Pressure
relief
valve
Pressure
gauge
Air filter
Blower
Air velocity
rotameter
AIR
INJECTION
WELL
Note: Not to Scale
MONTGOHEKVWKrSON
SCHEMATIC OF BIOVENTING
SYSTEM DESIGN
FIGURE 13
-------
KEY HAT
OT-69TCEPIumn
(OuUlo* is 5 H9/L Contour)
APPROXIMATE SCALE IN FEET
So«c»,
MONTGOMDIV MWCT50N
GEORGE AIR FORCE BASE
SITE OT-69 LOCATION MAP
Figure
14
-------
s-
8
Tables
MONTGOMERY WATSON
-------
-------
TA6lfil
RECOMMENDED REMEDIAL ALTERNATIVES FOR OU 3 SITES
Site
DP-OI
DP-02
DP-03
DP-04
LF-07"
LF-08*
RW-09*
DP-IO*
*
LF-ll
LF-12
LF-13
LF-14
DP-15*
WP-16
WP-17
SD-18
FT-19a
FT-19b
FT-I9C
FT-20(soil)
SS-21
OT-22
SS-23
SS-24
SD-27
SD-28
WP-29
WP-32
DP-33"
Description
Paint drum burial
Pesticide and paint burial
Acid and oil burial
Pesticide and oil burial
Base landfill
Tctraethyl Lead (TEL) disposal
Radioactive disposal
Landfill (cartridges)
Landfill (paper)
Landfill street sweeping: disposal site
Original base landfill
Base landfill
Munitions/oil
POL leach field
POL leach field
Fuel and oil disposal
Fire training area
Waste burn pit
Fire training area
Abandoned fire training area
Tip tank drainage area
Golf course/waste water treatment plant imgatioi
Salvage yard/hazardous waste storage yard
Building 580 unserviced transformer storage
Abandoned drain pit/dry well
Abandoned drain pit/dry well
Sludge drying beds
Leach field
Munitions
Presenting
Selected
Remedy
WPA
WPA
OU3FS
OU3FS
OU3FS
OU3FS
OU3FS
OU3FS
WPA
OU3FS
OU3R1
OU3FS
OU3FS
OU3RI
OU3FS
WPA
OU3FS
NA
OU3FS
OU3FS
OU3RI
WPA
OU3RI
WPA
OU3RI
OU3RI
WPA
OU3RI
OU3FS
Activities
Conducted
By:
MW
MW
MW
MW
IT
MW
-
MW
MW
MW
MW
M&E
M&E
-
M&E
M&E
M&E
MW
M&E
.
M&E
.
M&E
MW
.
MW
MW
Reuse
Parcel
(USAF.1993)
D
A,D
A
A
K
K
K
K
K
D
C
A.D
K
D
D
A, B
A
A
A
C
C
F.J
D
C
D
C
C
C
K
Selected Remedy
NFA
NFA
Alternative 4 (Soil Cover)
Alternative 4 (Soil Cover)
Alternative 3 (Surface Controls/Existing Cover Rehabilitation) *
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)*
Alternative 3 (Surface Controls/Existing Cover Rehabilitation) *
Alternative 3 (Surface Controls/Existing Cover Rehabilitation) *
NFA
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)
NFA
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)'
NFA
Alternative 9 (Biovenling)
NFA
Alternative 9 (Bioventing)
Alternative 6 (No Action With Monitoring)
.. Alternative 8 (Soil Vapor Extraction)
NFA
NFA
NFA
NFA
NFA
NFA
NFA
NFA
NFA
Alternative 3 (Surface Controls/Existing Cover Rehabilitation) '
-------
RECOMMENDED REMEDIAL ALTERNATIVES FOR OU3 SITES
(P*«e2or3)
Sttecled
DP-34*
LF-35
LF-36
LF-37
LF-38
LF-39
WP-401
SDMI
SD42
LF-43
LF-44
LF-45
DP-46
DP-47
OT-48
OT-49
OT-50
OT-51
SS-52*
SS-53
SS-55
ST-56
SS-59
DP-60
OT-61 ,
OT-62
WP-63
OT-64
OT-65
Munilioru/bombs
Landfill (wood/debrit di$pos«J)
Conslniclion debris/botrow pit
Landfill (road nuttritls buriil)
Trash disposal
Conilruction debris/trmh
Chemical toilet iludje
Riprap for industrial drain dischtrje
Ripnsp for off-base water supply
Rubble disposal
Misc. trash/rubble disposal
Conslniclion demolition
F-l 11 Aircraft burial
Aircraft parts burial
Salvage yard
Aircraft crash residues
Earth embankment
Test cells 799
Creosote spill area
Jet fuel spill
Fuel spill collection point
Spill near Building 549
Building 819 fuel spill
Sewerage sludge disposal
Shop waste disposal area
Rinse water disposal pit
Sewage sludge disposal areas
Transformer sites
Outlying revetments
OU3FS
WPA
WPA
OU3RI
OU3RI
OU3RI
OU3FS
WPA
WPA
WPA
OU3FS
WPA
OU3R1
OU3RJ
WPA
WPA
OU3RI
OU3FS
OU3FS
WPA
OU3RI
OU3RI
OU3FS
OU3R1
WPA
WPA
WPA
WPA
OU3RI
MW
.
,
MW
MW
MW
MW
.
.
.
MW
_
MW
MW
.
_
M&E
M4E.MW
MW
.
MW
MW
M&E
MW
.
_
,
_
MW
Activities
CtoKbcted P»«d
By: JUSAF. 19931
K
A.D
A
B
B
D.J
K
A
NA
A
D
A
D
C
D
NA
B
B
K
D
C
C
B
A
NA
NA
NA
NA
NA
Allemttive 3 (Surface Controls/Existing Cover Rehabilitation)'
Lind Use Restrictions/Posting of Warning Signs
NFA
NFA
NFA
NFA
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)1
NFA
NFA
NFA
Alternative 2 (Institutional Controls)
NFA
NFA
NFA
NFA
NFA
NFA
Alternatives 9 (Bioventing) and Natural Attenuation
Alternative 3 (Surface Controls/Existing Cover Rehabilitation)'
NFA
NFA
NFA
NFA
NFA
NFA
NFA
NFA
NFA
NFA
-------
T.
Site
Notes:
Description
RECOMMENDED REMEDIAL ALTERNATIVES FOR OU 3 SITES
(p«tt3of3)
it InvatJg»ti(m"
Presenting Activities Reuse
Selected Conducted Parcel
Remedy
OT-66 Nonpoinl-source residential housing WPA
WP-68 Paint disposal pit
OT-69 fCEfKE Plume
OU3RI MW
ITRI/FS IT
IRP Site Total 60 b
JUMF, mj)
NA
£
— - — - — — — — ___^_^^__ _
Selected Remedy
NFA
NFA
located outside of the FS remediation boundary
b Sites FT- I9a and FT- I9c mj counted as one site.
Alternative G-2 (Natural Attenuation/Institutional Omimlci
' ' M°' ™d SS'52' Slle LIM ' is P"1 of *" SEDA: «">*ev«r, it is
Acronyms: FS = OU 3 Feasibility Study Report (Montgomery Watson. I997a)
IT RI/FS = IT KUFS for OU 3 PCOTCE Study Area (IT. I995a)
M&E = Melcalf&Eddy
MW = Montgomery Watson
NA = Not Applicable
NFA = No Further Action
OU = OperaMeUnit
PCE = letrachloroelhene
RI = OU 3 Remedial Investigation Report (Montgomery Watson, I996a)
TCE = irichloroethene
WPA B Wotk Plan Addendum (JMM, 1992)
-------
TABLE2
SUMMARY OF OU 3 LANDFILL SITE CHARACTERIZATIONS
Site
Nam*
Sampling RatfaMalt/lnTcttijraUon Results
Human
Health Rhk b
DP-03
• CPR indicated buried debris covering approximately 2 acres.
•Trace soil-gas detected.
• Nine SVOCs delected in one of the three surface sampla.
• Fill maierialJ including concrete, asphalt, metal, and travel encountered at depths up to 7
feet in two of the three test pits.
• to the three subsurface samples, one VOC. 10 SVOCs. hydrocarbons, and lead detected
above background levels.
' Vadose zone modeling indicated no risk to groundwater.
• Cumulative Cancer
Riskd.9E-5
(industrial/commercial
worker scenario)
• Hazard Index < 1.0
•BloodLead < 10
A limited potential
for ecotopcal risk
due to a limited
distribution of PAHs.
• GPR indicated buried debris covering approximately 5.5 acres.
• Trace soil-gas detected.
• Three inorganics (lead, nickel and zinc) were detected above background in one of the
three surface samples. Three pesticides and hydrocarbons were also detected.
• Fill materials including concrete, asphalt, metal, plastic, wood, and gravel encountered at
depths below J5 feet in five of the six lest pits.
• Hydrocarbons, and two inorganics (lead and mercury) detected above background levels
in the subsurface samples.
• Vadose zone modeling indicated no risk to groundwater.
• Cumulative Cancer
Risk-6.7E-5
(industrial/commercial
worker scenario)
•Hazard Index < 1.0
• Blood Lead < 10
A potential ecological
risk 10 burrowing
mammals and their
predators due mainly
to the highly
localized presence of
Aroclor 1260.
• GPR indicated buried debris covering approximately 4 acres. . Qunui.^ CtDea
• Three dioxins. hydrocarbons and four inorganics (barium, lead, mercury and zinc) detected 2^, rl^nt^a^
above background in surface soil samples. rcswem scenano)
• Fill materials including concrete, metal, plastic, glass and plaster board encountered to . Hazard Inda < I 0
depths of 10 feet in ten pits. ™«iiin»«« i.u
• Hydrocarbons, and barium detected above background levels in the subsurface sample*. . Blood Lead < 10
• Inorganic constituents below or near background were detected in groundwater.
• Vadose zone modeling indicaled no risk to groundwater.
A potential ecological
risk to burrowing
mammals iind their
predators due mainly
to the highly
localized presence of
dioxins, kid. zinc.
and barium.
• GPR indicated buried debris covering approximately 9 acres.
• Trace soil-gas detected.
• Four SVOCi. two pesticides, hydrocarbons and five inorganics (cadmium, copper, lead.
mercury and zinc) detected above background in surface soil samples.
• Rll materials including concrete, asphah. metal, plastic, wood, glass and gravel
encountered at depths below 15 feet in lest pits.
• Two VOCs. one SVOC. hydrocarbons, and two inorganics (lead and manganese) detected
above background levels in the subsurface samples.
• loorganic constituents below or near background were detected in groundwater.
• Vadote zone modeling indicated no risk to grouodwater.
• Cumulative Cancer
RUk»I.OE-5
(industrial/commercial
worker scenario)
•HazardIndex < 1.0
•BloodLead < 10
A potential ecological
risk to burrowing
mammals and their
predators due to the
localized presence of
cadmium, lead, zinc.
pesticides, ind PAHs.
• GPR indicated buried debris covering approximately 0.41
• Trace toil-gas detected.
• Hydrocarbons and lead delected above background in surface soil samples.
• Fill materials including concrete, metal, wood, trash and burned debris encountered to
depths up 10 9 feet in test pits.
• Hydrocarbons and two inorganics (antimony and lead) detected above background levels
in the subsurface samples.
* Vadose zone modeling indicated no risk to groundwater.
• PRO screening
indicated site
chemicals are within
acceptable levels;
therefore a risk
calculation was not
perfuciiKd.
•Blood Lead < 10
Ecological impacts
not significant.
• • GPR indicated buried debris covering approximately 50 acres.
• Trace soil-fa* detected.
• Eight djoxint. one pesticide, hydrocarbons and 10 inorganics detected above background
in surface soil samples.
• Fill materials including concrete, asphalt, metal, rubber, wood, glass, plaster board, and
burned debru encountered al depths below 13.5 feet in test pits.
• Toluene, hydrocarbons, and 14 inorganics detected above background levels in the
subsurface samples.
• Inorganic constituents below or near background were detected in groundwater.
• Vadoae zone modeling indicated no risk to groundwater.
• Cumulative Cancer
Risk -S.4E-5 (future
adult resident scenario).
• Hazard Index -1.36
• Blood Lead < 10
A potential ecological
risk to burrowing
mammals and their
predators due; to the
localized pretence of
several metals and
dioxin/furan
congeners.
Notes:
a The SEDA remediation boundary includes 9 sites (LF-07, LF-08. RW-09, DP-IO. DP-IS. DP-33. DP-34. WP-40. and SS-J2).
b Highest cancer risk from all scenarios evaluated the scenario under which the highest cancer risk was calculated is presented.
-------
TABLE 3
SUMMARY OF DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES FOR OU 3 LANDFILL SITES
Alternative
Protection of
Human Health
and the Compliance with
Environment ARARs
Effectiveness Reduction of TMV
ImplementabilitY Total Cost
I. No Action with
monitoring
Does not reduce Does not comply.
potential for
future exposure.
Not effective. No reduction of TMV.
No technical
limitations.
See Table 5.
2. Institutional Controls
Reduces potential Complies with Moderate
for future ARARs. effectiveness.
exposure
Reduces volume through Easily implemented. See Table 5.
surface restoration.
3. Surface Controls/
Existing Cover
Rehabilitation
Significantly Complies with
reduces potential ARARs.
for future
exposure.
Effective. Reduces the mobility of General site grading See Table 5.
the landfill contaminants may be difficult in
< by reducing surface water areas of uneven
infiltration and controlling topography.
run-on/runoff.
4. Soil Cover
Significantly Complies with
reduces potential ARARs.
for future
exposure.
Effective. Same as Alternative 3, but Same as Alternative See Table 5.
provides greater reduction 3.
in infiltration through the
addition of a soil cover.
5. Synthetic Cap
Significantly Complies with
reduces potential ARARs.
for future
exposure.
Effective. Same as Alternative 4, but Same as Alternative See Table S.
provides a greater 3.
reduction in infiltration
through the addition of a
synthetic liner.
ARAR - applicable or relevant and appropriate
TMV - toxicity, mobility, or volume
-------
TABLE4
ARAR. FOR GAFB OU 3 LANDHLL SITES DP43. DP-W, LF-12, LF-I4, AND THESEDA
(P«C« t of »)
Sonrco
Standard Requirements,
Critorton, or Limitation*
ARARStataf'
Description
Coiucftt
California Integnted Watte
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Watte
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 ft 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
14 CCR 17766
Chapter 3. Article 7.8
Disposal Site Closure and
Poitclocure Maintenance
14CCRI7767c,d,e.f.&g
Chapter 3. Article 7.8
Disposal Site Closure and
Poitclosure Maintenance
14CCR1777la(2)
Chapter 3. Article 7.8
Disposal Site Closure and
Postclosure Maintenance
14 CCR 17772
Chapter 3. Article 7.8
Disposal Site Closure and
Postclosure Maintenance
14CCRI7773a&c-e
Chapter 3. Article 7.8
Disposal Site Closure and
Postclosuie Maintenance
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
14 CCR 17774 a-e{D & H Relevant and Appropriate
Emergency Response Plan: potential emergency conditions
that may exceed the design of the site and could endanger the
public health or environment must be anticipated. Response
procedures for these conditions must be addressed in the
RD/RA plans.
Security at Closed Sites: all points of access to the site must
be restricted, except permitted entry points. All monitoring.
control, and recovery systems shall be protected from
unauthorized access. Notification signs must be posted at the
site,
Structure Removal: dismantle and remove structures are
required by the closure plan.
Chapter 3, Article 7.8
Disposal Site Closure and
Poitcloiure Maintenance
Decommissioning of Environmental Control Systems:
components of the environmental control systems, which
have come into contact with leacbate or landfill gas need to
be dismantled and disposed of in a manner that will not pose
a potential health threat.
Final Cover: the design and construction of the final cover
must meet specific performance standards regarding
infiltration. landfill gas emissions, and reuse of the site. This
section incorporates the prescriptive standards of 23 CCR
2581(a); however, an engineered alternative that meets the
performance standards is being proposed and must meet the
engineered alternative criteria including 23 CCR
25IO(b)&(c)and2580(e).
Construction Quality Assurance (CQA): a CQA program
must be designed and irnpkineRisd. it must include specific
parameters (and for some components specific testing
methods) for the final cover.
Closure or Postclosure
Maintenance Standard of Title 14,
CCR, Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure of Poslclosure
Maintenance Standard of Title 14,
CCR, Chapter 3. Article 7 J.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14.
CCR, Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14,
CCR, Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14.
CCR, Chapter 3. Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14,
CCR. Chapter 3. Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
-------
TABLE4
ARARi FOR GAFB OU 3 LANDFILL SITES DP-03, DP-M, LF-12, LF-14, AND THE SEDA
(P«gt2of9)
Source
Standard Requirements,
Criterion, or LlmlUttoii'
ARAR Status*
Description
Comment
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 ft 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
14 CCR 17776
Chapter 3. Article 7.8
Disposal Site Closure and
Postclosure Maintenance
Relevant and Appropriate
14 CCR 17777m
Chapter 3, Article 7.8
Disposal Site Closure and
Postctofure Maintenance
14 CCR 17778
Chapter 3, Article 7.8
Disposal Site Closure and
Postclosure Maintenance
14 CCR 17779
Chapter 3. Article 7.8
Disposal Site Closure and
Postclosure Maintenance
14 CCR 17781 a&b
Chapter 3, Article 7.8
Disposal Site Closure and
Postclosure Maintenance
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Final Grades: the Anal grades for the covered landfill must
meet grading standards provided in 23 CCR 2581 (b). and be
based on local topography, climate condition!, and
postclosure land use; they must be appropriate to control
runoff and erosion. Survey monuments must be installed to
monitor settlement as required by 23 CCR 2580(d). Upon
completion of closure activities and in the postclosure
maintenance period, contour maps are required to calculate
settlement using 2 foot contour intervals and the scale
specified in 23 CCR 2S97(b).
Hnal Site Face: the design of the final site face must provide
for the integrity of the final cover both under static and
dynamic conditions.
Final Drainage: the design of the final cover and any
associated collection and holding facilities must control
runon and runoff produced by a 100-year 24-hour storm
event as required by 23 CCR 2S46(a),(c) & (D) and
2S9S(d)(2) and must be prepared according to CQA
requirements.
Slope Protection and Erosion Control: the design and
construction of the slopes must protect the integrity of (be
final cover and minimize soil erosion.
Leachate Control During Closure and Postclosure: if
leachate is being produced at the site, it must be monitored,
collected, treated, and discarded pursuant to 23 CCR 2SS9,
2543. and 2546(b), respectively.
Closure or Poslclosure
Maintenance Standard of Title 14,
CCR, Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14,
CCR. Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure or Postclosure
Maintenance Standard of Title 14,
CCR, Chapter 3. Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Closure and Postclosure
Maintenance Standard of Title 14,
CCR. Chapter 3, Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
The state does not intend that
subsurface leachate monitoring
and collecting systems need to be
added to existing landfills unless
leacbate production and/or
accumulation is evident.
-------
f
TABLE4
ARARf FOR GAFB OU 3 UNDFILL SITES DP43, DP.04, LF-12, LF-14, AND THE SEDA
(Fate 3 of 9)
Source
Standard Requirement*,
Criterion, or Lfanltatleo'
California Integrated Wute
Management Act of 1989
PRC 40502 & 43020
California Integrated Watte
Management Act of 1989 -
PRC 40502 ft 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43020
California Integrated Waste
Management Act of 1989
PRC 40502 & 43509
California Integrated Waite
Management Act of 1989
PRC 40502 & 43509
California Integrated Wute
Management Act of 1989
PRC 40502 & 43509
14 CCR 17783
(attempting m exemption)
Chapter 3. Article 7.8
DiipoMl Site Clowns and
Poitdonire Maintenance
14 CCR 17788
Chapter 3. Article 7.8
Disposal Site Cloiure and
Postckuure Maintenance
14 CCR 17796
Chapter 3. Article 7.8
Disposal Site Closure and
Poitclosure Maintenance
14 CCR 18262 Ja(l-5B)i
(8) Chapter 5. Article 3.4
Closure Plans
I4CCR18265.3a(l-7)and
(9 & 10) Chapter 5, Article
3.4, Poitclosure
Maintenance Plans
14 CCR 18275 Chapter 5,
Article 3.4, Postckuure
Maintenance Plans
ARAR Statue*
Relevant and Appropriate
Relevant and Appropriate
Applicable
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Description
Gas Monitoring and Control During Closure and Port
Closure: landfill gases must be collected and analyzed; (he
concentration of combustible gas at the landfill boundary
must be 5 percent or leu, (race gases must not be at levels
that cause adverse health or environmental impacts.
Postclosure Maintenance: the landfill must be maintained
and monitored for no less than 30 yean following closure
and in accordance with 23 CCR 2581 (c).
Postctosure Land Use: Site Closure Design shall show one
or more proposed uses of the closed site or show
development that is compatible with open space. The owner
of the site must notify the agencies of any proposed change*
in postclosure land. Changes in the land use must be
implemented in accordance with the standards in this section
to ensure that public health and the environment are
adequately protected.
Provides the content requirements for closure plans for solid
waste disposal sites.
Provides the content requirements for poatctosure
maintenance plans for solid waste disposal sites.
Provides the content requirements to obtain certification that
the solid waste disposal sites has closed pursuant to state
standards.
Comment
An exemption may be granted
pursuant (o 14 CCR 17783.17 once
the proposed monitoring data it
received,
Maintenance and monitoring is to
continue for 30 years following
closure until it can be
demonstrated that the landfill does
not pose a threat to public health
and safety or a threat to the
environment.
Closure or Postclosure
Maintenance Standard of Title 14.
CCR. Chapter 3. Article 7.8.
Scope and Applicability pursuant
to 14 CCR 17760.
Applies to solid waste disposal
site* that received waste after
January 1,1988.
Applies to solid waste disposal
sites that received waste after
January 1,1988.
Applies to solid waste disposal
sites that received waste after
January 1,1988.
-------
TABLE4
ARARi FOR GAFB OU 3 LANDFILL SITES DP-03, DP-04, LF-12, LF-14, AND THE SEDA
(P»«c 4 of 9)
Source
Standard Requirements,
CriUrioa. or Umrtalton*
ARAR Status'
Description
Conuacnt
Water Quality Control Plan Table 2-1, Beneficial Uses Applicable
for the Lahontan Region of Ground Waters in Upper
(Basin Plan) Mojave Hydro-logic Unit
(628.20)
Objectives for Ground
Water
California Water Code J
13176
California Water Code 5
13370 etteq.
Applicable
Applicable
Applicable
California Water Code §
13750
Applicable
California Water Code } Applicable
13750.5
California Water Code } Applicable
13752
Defines beneficial uses for groundwaters beneath GAFB as:
municipal, agricultural, industrial service, and freshwater
replenishment.
Defines the groundwater quality objectives for:
nondegradation, taste and odor, bacteria, chemical
constituents, radioactivity, and minerals.
Requires the analysis of material to be performed in a State
certified laboratory.
Requires compliance with Federal Clean Water Act
requirements for surface water discharges. Includes National
Pollutant Discharge Elimination System Requirements for
storm water runoff from certain construction or industrial
activities. The Air Force must comply with the substantive
requirements for a) eliminating most non-storm water
discharges, b) developing and implementing a storm water
pollution prevention plan, and c) performing monitoring of
storm water discharges. For landfills that are inactive, prior
to final closure, these regulations are contained in the
SWRCB General Industrial Storm Water Permit (Order No. .
91-13-DWQ. as amended by Order No. 92-12-
DWQXNPDES No. CAS000001). For Landfills that are
going through final closure, these regulations are contained
in the SWRCB General Construction Activity Storm Water
Permit (Order No. 92-08-DWQ)(NPDES No. CAS000002).
Requires an intent to drill notice to be filed with the State
Department of Water Resources for water wells, monitoring
wells, and cathodic protection wells.
Requires well drillers to possess a C-57 license.
Allows other governmental agencies to obtain and submit
well reports, provided (he public is allowed to see them only
after obtaining written permission from the owner.
The identification of the
groundwaters beneath landfill sites
as potential drinking water sources
forms a basis for selection of
concentration limits, cleanup
levels, and treatment levels.
Concentration limits, cleanup
levels, and treatment levels must
conform to the objectives.
For all investigation and remedial
actions.
For any well.
For any well.
For any well.
-------
TABLE*
ARAR, FOR GAFB OU3LANDFILLSnESDP^,DP^LF.12,LF.M,AND™ESEDA
(Pa je 5 of 9)
Source
Standard Requirements,
Criterion, or Limitation1
Discharges of Water to 5 25 1 0(g)
Land. Chapter 15, Title 23.
CCR. Article 2 - Waste
Classification and
Management
52520
* M£ Ml
$2523
Discharges of Waste to } 2546
Land. Chapter 15, Title 23.
CCR. Article 4-
Construction Slandards
52550.1
Porter-Cologne Act { 2550 4
Chapter 15
}2550.7(bXIXA)
|2550.7(bXIXB>
§ 2550.7(b)(2)
• .- .
— fttvin awuy
DMCriPtion Comment
Relevant «! Appropriate C.o^ inactive, or abandoned waste management units as
of 1 1/27/84 may be required to implement a monitoring
program. If water quality impairment is discovered
corrective action may be required.
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
^SSSS^^"*** ^ — withintheselandfiUs
solid waste.
Non-Hazardous Solid Waste - putrescible and non-
putrescible waste that may be discharged to a Class III unit.
Precipitation and Drainage Controls - criteria for diversion
and drainage of storm water.
Defines the type of monitoring programs that apply.
Different monitoring programs may apply at the same unit at
the same lime. TTie requirements (ROD) must specify the
type of program applicable to the unit.
Concentration Limits (CL) - Must be established for
groundwater. surface water, and the unsaturated zone. Must
be based on background, equal to background, or for
corrective actions, may be greater than background
(CLGTB), not to exceed the lower of the MCL or the
concentration technologically or economically achievable. ,
Have a "sufficient number" of background MPts.
For detection monitoring, have a sufficient number of MPts
at the POC. additional locations as necessary, unsaturaied
zone, perched aquifers, and zones of highest conductivity.
Background monitoring does not necessarily have to be
upgradient of unit, ii may be representative of uparadient
conditions.
* < • '
-------
TABLE4
ARARs FOR GAFBOU 3 LANDFILL SITES DP-03, DP-04, LF-12, LF-M, ANDTHESEDA
(Page C of 9)
Source
Standard Requirements,
Criterion, or Limitation'
ARAR Status1
Description
Comment
|2550.7(bM4)
|2550.7(bX5)
|2550.7(bX6)
12550.7(bX7)
J2550.7(eX2)
}2550.7(eX3)
S 2550.7(eX4)
J2550.7(e)(5)
{ 2550.7(eX6)
§ 2550.7(e)(7)
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Monitoring wells are to be constructed and cased in a manner
to prevent being a conduit for contaminant transport.
Sampling interval shall be appropriately screened and
equipped with a filter pack to enable representative
groundwater sample collection.
The annular space (hall be appropriately sealed to prevent
cross-contamination.
Monitoring wells are to be adequately developed.
Cuttings to be logged during drilling under supervision of a
registered geologist, lithology logs submitted to Regional
Boards: Soils - USGS, Rocks - as appropriate. Unsaturated
Zone • record depth and thickness.
Separate groundwater monitoring systems are not necessary
for contiguous units.
Consistent sampling and analytical procedures are required
incorporating: sample collection, sample preservation and
shipment, analytical procedure!, and chain-of-custody
control.
Monitoring program to include appropriate methods for each
COC and monitoring parameter (MPa).
For each unit collect all data necessary to select an
appropriate statistical method for establishing background.
As a minimum, quarterly sampling for one year, considering
highest and lowest groundwater elevations.
Propose a statistical method for evaluation of each COC and
MPa. Mutt be specified in requirements (ROD). Selection
criteria are given.
Far all wells.
For all wells.
For all wells.
For all wells.
For all wells.
The monitoring parameters are the
metal surrogates chloride, sulfate,
nitrate as nitrogen, total dissolved
tolids, and volatile organic
constituents as defined by
Appendix I of 40 CFR 258. The
constituents of concern are those
constituents listed in Appendix II
of 40 CFR 258.
-------
TABLE4
ARARi FOR GAFB OU 3 LANDFILL SITES DP-03, DP-W, LF-12, LF-14, AND THE SEDA
(P*C«7of>)
Source
Standard Requirement*,
§2550.7(eX8)
12550.7(eX9)
S 25S0.7(eX10)
52550.7(e)(ll)
} 2550.7(eX12)
52550.7(eXl3)
52S50.7(e)(14)
§ 2550.7(eXI5)
ARAR Statin*
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Description
Acceptable Statistical Methods:
- ANOVA using mean values
- ANOVA using median values
- Tolerance or Prediction Interval
- Control Charts
- Alternate Proposal, verification criteria are included.
Performance Standards are given for each statistical method.
Based upon the data collected and statistical method chosen
to analyze the data, propose and justify a procedure to
determine background for each COC and MPa, may use:
- background
- method to update background with new data.
The requirements (ROD) shall specify the method chosen
above.
for each COC and MPa the requirements (ROD) shall
specify the sampling methods to establish background and
for monitoring, consistent with:
- the appropriate number and kind of samples for the
statistical lest chosen
• (he sampling method, including frequency and interval.
ensuring independent samples.
Must collect groundwater surface elevation and field
parameters each time a well is sampled.
All data must be graphed at least manually, criteria are given
graphs.
Comment
Relevant and Appropriate The groundwater flow rate and direction must be determined.
For each well.
Except where there is no new data,
the guidelines of the PAT
documents entitled Lone Term
Manife^Md Reporting
Hvdf oeeologic Date arr
appropriate.
RPMs should adjust this
requirement as necessary. Semi-
annual determination should be
adequate.
-------
TABLE4
ARARi FOR GAFB OU 3 LANDFILLSITES DP-03, DP-04, LF-12, LF-I4, AND THE SEDA
(Pace 8 of 9)
Source
Standard Requirement!,
Criterion, or Limitation'
California Well Standards
for water wells, monitoring
wells, and camodic
protection wells
Hazardous Waste Control
Laws
California Health and Safety
Code, Div. 26, Chapter 13
i 2550.7(eXI6)
} 2550.8
12550.8(d)
12S50.8(e)
J 2550.8(1)
J 2550.8(g)
} 2S50.8(b)
{ 2550.g(i)
}2580(c)
BuUetin 74-90 and 74-81,
adopted pursuant to
California Water Code §
13800
Title 22, California Code of
Regulations (CCR). Division
4.5 Environmental Health
Standards for Management
of Hazardous Waste,
Chapters 11.12. 14, and 18
Mojave Desert Air Quality
Management District
(MDAQMD), Rule 401
ARAR Status'
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
Relevant and Appropriate
To Be Considered
Applicable
Comment
Applicable
All data collected shall be maintained. The requirements
(ROD) shall specify when data are to be reported.
Detection Monitoring.
The requirements (ROD) shall specify the WQPS.
MPas shall be proposed and specified in requirements
(ROD) to include physical parameters, hazardous
constituents, and reaction products to provide a reliable
Indication of a release. A list of items to consider is given.
Monitoring parameters and frequencies shall be as specified.
COCs to be monitored if there is statistic evidence of a
release.
All data must be maintained so that statistical evidence of a
release may be determined.
Lists criteria for determining statistical evidence of a release,
includes physical determination (i.e., rapid pond declines or
spills).
Prevents excessive irrigation on the final cover.
Provides minimum construction and destruction criteria for
water wells, monitoring wells, and cathodic protection wells.
Also includes criteria for borehole abandonment
Regulations governing hazardous waste control;
identification and listing of hazardous waste, standards
applicable to generators of hazardous waste waste transfer;
treatment, storage, and disposal facilities; and land disposal
restrictions.
This rule prohibits the discharge of air contaminants which
obscure visibility by more than 20 percent for a period of
more than 3 minutes in any I hour.
MPas may be known as the Short
List at opposed to the Long List of
COCs.
For all wells.
Only applicable if the wastes from
the sites are classified as
hazardous waste.
This regulation is applicable to any
remedial action activity, which
may cause a visible emission.
-------
TABLE4
ARAR. FOR GAFB OU 3 LANDFILL SITES DP4>3, DP-04, LF-12, LF-14, AND THE SEDA
Source
Siaadard Requirements,
Criterion, or LtmlUtkn*
ARAR Status*
Dqcriptlon
Couufit
California Health uid Safety MDAQMD, Rule 402 Applicable
Code, Div. 26. Chtpler 13
California Health and Safety MDAQMD. Rule 403 Applicable
Code, Div. 26, Chapter 13
California Health and
Safety Code, Div. 26,
Chapter 13
MDAQMD, Rule 1303 Applicable
This rule prohibits the discharge of air contaminants in
quantities which may cause injury, detriment, nuisance, or
annoyance to any considerable number of persons or which
endangers the comfort, response, health, or safety of any
such person or which causes or has natural tendency to cause
injury or damage to business or property.
This rule requires a person to lake reasonable precaution not
to cause or allow emissions of fugitive dusts from being
airborne beyond the property line from which the emission
originated.
This rule requires (he installation of best available
technology (BACT) to a new emission unit or modification
of existing emissions unit.
This regulation ii applicable to any
remedial action activity, which
may discharge air contaminants as
denned by the rule.
This regulation is applicable to any
remedial action activity, which
may cause the release of fugitive
dust
This regulation is applicable to any
remedial action activity that may
cause the emissions of 25 pound
per day or more of any
Nonanainment Air Pollutant
1 Sections of Title 14 CCR and Title 23 CCR have been recodified into Title 27 CCR.
' The State does not agree on the characterization of certain ARARs in this table to be
the ROD at ARARs, the State will ool dispute this ROD.
14 CCR - California Code of Regulations. Title 14
23 CCR - California Code of Regulation*. Tide 23
ANOVA - Analysis of Variance
ARAR - applicable or relevant and appropriate requirement
BACT - best available technology
CFR - Code of Federal Regulations
CL - concentration limits
CLGTB - Concentration Limit Greater than Background
COC - Constituent of Concern
CQA - Construction Quality Assurance
MCL - Maximum Contaminant Level
MDAQMD - Mojave Desert Air Quality Management District
Mrs - monitoring parameter
MPu - Monitoring Points
POC - Point of Compliance
RD/RA - remedial design/remedial action
ROD - Record of Decision
RPM - remedial project manager
WOPS - Water Quality Protection Standards
See Title 27 CCR for the new equivalent section numbers that apply.
"Relevanl and Appropriate" instead of "Applicable." However, because these requirements will be included in
WOPS-
-------
TABLES
SUMMARY OF PRELIMINARY REMEDIAL ALTERNATIVE COSTS FOR OU 3 LANDFILL SITES
Site Cost Criteria
Alternative 1 Alternative 2 Alternatives Alternative 4 Alternatives
DP-03
DP-04
LF-12
LF-14
LF-44
SEDA
^ VBHWVII^
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present- Worth Cost
Construction Cost
Direct Capital Cost
Total Capita! Requirement
30- Year Present-Worth Cost
— —
$5,000
$6,500
$8,000
$460,000
$5,000
$6,500
$8,000
$420,000
$0
$0
$0
$450,000
$0
$0
$0
$530,000
$0
$0
$0
$370,000
$0
$0
$0
$970,000
- ••--
$69,000
$90,000
$170,000
$680,000
$70,000
$91,000
$170,000
$640,000
$130,000
$170,000
$270,000
$830,000
$330,000
$420,000
$600,000
$1,400,000
$34,000
$44,000
$110,000
$510,000
$610,000
$780,000
$1,100,000
$2,600,000
$230,000
$290,000
$440,000
$1,100,000
$200,000
$260,000
$400,000
$980,000
$430,000
$540,000
$780,000
$1,600,000
$1,300,000
$1,600,000
$2,200,000
$3,800,000
$130,000
$160,000
$270,000
$740,000
$2,700,000
$3,400,000
$4,600,000
$7,800,000
$280,000
$360,000
$540,000
$1,200,000
$250,000
$320,000
$480,000
$1,100,000
$560,000
$710,000
$1,000,000
$1,900,000
$1,800,000
$2,300,000
$3,200,000
$5,300,000
$150,000
$190,000
$310,000
$800,000
$3,800,000
$4,800,000
$6,500,000
$11,000,000
$370,000
$470,000
$680,000
$1,400,000
$340,000
$440,000
$640,000
$1,300,000
$860,000
$1,100,000
$1,500,000
$2,700,000
$2,700,000
$3,400,000
$4,600,000
$7,400,000
$190,000
$240,000
$370,000
$900,000
$5,800,000
$7,300,000
$10,000,000
$16,000,000
" Costs are as presented in the OU 3 FS Report (Montgomery Watson, 1997a).
-------
TABLE 6
PRELIMINARY COST ESTIMATE FOR SITE DP-03 PREFERRED ALTERNATIVE
(Page 1 of 2).
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
GENERAL
Construction Trailer (Rental)
Temporary Utilities (Telephone/Power)
Decon Trailers
Health & Safety Equipment
Vehicle Decon Station
Vehicle Decon Equipment
Dust Control
Mobilization
Demobilization
SITE WORK
Clear and Grub (w/ Class in Disposal)
Soil Testing (compaction and density)
Excavate Native Soil (within 1 mile)
Haul and Dump Native Soil
Fill, Spread, and Compact Soil
General Site Grading (min. 3% slope)
Construct Drainage Channels (riprap)
Erosion Control and Revegetation
Maintain and Repair Haulage Roads
Chain-Link Fencing (8 ft high. Barbed)
Downgradient Monitoring Well (Installed)
Supervision. Health & Safety
Bid Contingency
Scope Contingency
INDIRECT CAPITAL COST
Land Use Restrictions
Prc-Design Studies
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
1 month $500
1 month $1, 500
month $2,400
month $3,000
each $5,000
month 5700
month $11.000
lump sum $20.000
lump sum $15.000
180.000 SF $0.07
20 each $100
26.000 CY $1
26.000 CY $2
26.000 CY $0.50
180.000 SF $0.05
1.500 LF $20
180,000 SF $0.05
16,000 SF $0.90
2400 LF $20
1 lump sum $5,000
Subtotal Construction Cost (CC)|
10% of CC
IO%ofCC
8%ofCC
Subtotal Direct Capital Cost (DCC)|
1 lump sum $50,000
5% of DCC
5% of DCC
10% of DCC
15% of DCC
TOTAL CAPITAL REQUIREMENT 1
PERIODIC OPERATING AND MAINTENANCE COST
Annual Maintenance for Soil Cover
Annual Groundwatcr Monitoring (4 wells) —
5% of DCC
4 sample $3,000
$500
$1.500
$2,400
$3,000
$5,000
$700
$11.000
$20.000
$15,000
$12,600
$2,000
$26,000
$52,000
$13,000
$9,000
$30,000
$9.000
$14,400
$50,000
$5.000
$280,000 |
$28.000
$28,000
$22,400
$360.000 ]
$50.000
$18.000
$18.000
$36,000
$54,000
$540.000 |
$18,000
$12,000
-------
TABLE 6
PRELIMINARY COST ESTIMATE FOR SITE DP-03 PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Semi-Annual Groundwater Monitoring (2 wells)
Quarterly Groundwater Monitoring (1 well)
Semi-Annual Storm Water Monitoring (2 locations)
5- Year Site Review
PRESENT WORTH
Quantity
2
2
4
1
Unit
sample
sample
sample
lump sum
Discount Rate
Years
Unit Cost ($)
$3.000
$3.000
$2.000
$10,000
7%
30
Total Cost ($)
$6.000
$6.000
$8,000
$10.000
30-YEAR PRESENT WORTH COST | $ 1.200.0001
-------
TABLE 7
PRELIMINARY COST ESTIMATE FOR SITE DP-04 PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
GENERAL
Construction Trailer (Rental)
Temporary Utilities (Telephone/Power)
Decon Trailers
Health & Safety Equipment
Vehicle Decon Station
Vehicle Decon Equipment
Dust Control
Mobilization
Demobilization
SITE WORK
Clear and Grub (w/ Class in Disposal)
Soil Testing (compaction and density)
Excavate Native Soil (within 1 mile)
Haul and Dump Native Soil
Fill, Spread, and Compact Soil
General Site Grading (min. 3% slope)
Construct Drainage Channels (riprap)
Erosion Control and Revegetation
Maintain and Repair Haulage Roads
Chain-Link Fencing (8 ft high. Barbed)
Downgradient Monitoring Well (Installed)
Quantity Unit
month
month
month
month
.each
month
month
lump sum
lump sum
190.000 SF
20 each
21.000 CY
21.000 CY
21,000 CY
190,000 SF
1,300 LF
190,000 SF
12.000 SF
2,000 LF
1 lump sum
Unit Coat ($)
$500
suoo
$2,400
$3,000
$5,000
$700
$11,000
$20.000
$15.000
$0.07
$100
$1
$2
$0.50
$0.05
$20
$0.05
$0.90
$20
$5,000
Subtotal Construction Cost (CC)|
Supervision. Health & Safety
Bid Contingency
Scope Contingency
10%ofCC
JO%ofCC
8%ofCC
Subtotal Direct Capital Cost (DCC)|
INDIRECT CAPITAL COST
Land Use Restrictions
Pre-Design Studies
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
1 lump sum
5% of DCC
5% of DCC
10% of DCC
15% of DCC
$50.000
TOTAL CAPITAL REQUIREMENT |
Total Cost ($)
$500
$1.500
$2.400
$3.000
$5.000
$700
$11,000
$20.000
$15.000
$13,300
$2.000
$21.000
$42,000
$10^500
$9.500
$26,000
19.500
*W*v^\AJ
$10.800
$40,000
$5.000
$250.000 |
$25,000
$25,000
$20.000
$320,000 1
$50.000
$16,000
$16,000
$32,000
$48,000
$480,0001
Annual Maintenance for Soil Cover
5% of DCC
$16,000
-------
TABLE?
PRELIMINARY COST ESTIMATE FOR SITE DP-04 PREFERRED ALTERNATIVE
(Page2of2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
Annual Groundwater Monitoring (3 wells)
Semi-Annual Groundwater Monitoring (2 wells)
Quarterly Groundwater Monitoring (1 well)
Semi-Annual Storm Water Monitoring (2 locations)
5- Year Site Review
PRESENT WORTH
3
2
2
4
1
sample
sample
sample
sample
lump sum
Discount Rate
Years
$3,000
$3,000
$3,000
$2,000
$10,000
7%
30
$9,000
$6.000
$6,000
$8,000
$10,000
30-YEAR PRESENT WORTH COST | $1.100.0001
-------
TABLE 8
Item/Description
| _
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
GENERAL
Contraction Trailer (Rental)
Temporary Utilities (Telephone/Power)
Decon Trailers
Health & Safety Equipment
Vehicle Decon Station
Vehicle Decon Equipment
Dust Control
Mobilization
Demobilization
SITE WORK
Clear and Grub (w/ Class in Disposal)
Soil Testing (compaction and density)
Excavate Native Soil (within 1 mile)
Haul and Dump Native Soil
Fill. Spread, and Compact Soil
General Site Grading (min. 3% slope)
Construct Drainage Channels (riprap)
Erosion Control and Revegetation
Maintain and Repair Haulage Roads
Chain-Link Fencing (8 ft high. Barbed)
Supervision, Health & Safety
Bid Contingency
Scope Contingency
INDIRECT CAPITAL COST
Land Use Restrictions
Pre-Design Studies
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
PERIODIC OPERATING AND IVUINTENANCE COST
Annual Maintenance for Surface Controls
Annual Groundwatcr Monitoring (4 wells)
Qwntity Unit Unit Cost ($) Total Cost ($)
2 month 5500
2 month $1.500
2 month 52.400
2 month $3(0oo
' each 55,000
2 month $700
2 month $11,000
1 lump sum $20.000
1 lump sum 515,000
600.000 SF $0.07
20.000 CY '??
20.000 CY $2
20.000 CY $050
600.000 SF $oo5
1.800 LF $20
600.000 SF $005
4.000 LF W$S
Subtotal Construction Cost (CC)|
8%ofCC
10% of CC
8% of CC
ff.ft. t it:
auoiotaj Direct Capital Cost (DCC)|
1 lump sum 550,000
5% of DCC
5% of DCC
10% of DCC
15% of DCC
^^^A^- v- A fJiAL REQUIREMENT |
j -
5% of DCC
4 ^Pfe 53.000
$1.000
$3,000
$4.800
$6,000
55,000
51,400
522,000
520,000
515,000
542,000
56,000
520,000
540,000
$10,000
$30,000
S36.000
530,000
554,000
580.000
5430.000]
534,400
543.000
534,400
5540,000^
550.000
527,000
527,000
554.000
581,000
5780.000]
•
527,000
512,000
-------
TABLE 8
PRELIMINARY COST ESTIMATE FOR SITE LF-12 PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
Semi-Annual Groundwaier Monitoring (2 wells)
Quarterly Groundwater Monitoring ( I well)
Semi-Annual Storm Water Monitoring (2 locations)
5- Year Site Review
PRESENT WORTH
2
2
4
]
sample
sample
sample
lump sum
Discount Rate
Years
$3,000
$3,000
$2.000
$10.000
7%
30
$6.000
$6.000
$8,000
$10.000
30-YEAR PRESENT WORTH COST | $1.600.000]
-------
TABLE 9
PRELIMINARY COST ESTIMATE FOR SITE LF-14 PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
GENERAL
Construction Trailer (Rental)
Temporary Utilities (Telephone/Power)
Decon Trailers
Health & Safety Equipment
Vehicle Decon Station
Vehicle Decon Equipment
Dust Control
Mobilization
Demobilization
SITE WORK
Clear and Grub (w/ Class in Disposal)
Soil Testing (compaction and density)
Excavate Native Soil (within 1 mile)
Haul and Dump Native Soil
Fill. Spread, and Compact Soil
General Site Grading (min. 3% slope)
Construct Drainage Channels (riprap)
Erosion Control and Revegetation
Maintain and Repair Haulage Roads
Chain-Link Fencing (8 ft high. Barbed)
Supervision. Health & Safety
Bid Contingency
Scope Contingency
INDIRECT CAPITAL COST
Land Use Restrictions
Pre-Design Studies
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
4 month $500
4 month $1,500
4. _
month $2,400
4 month $3,000
2 each $5.000
4 month $700
4 month $] 1,000
I lump sum $20,000
1 lump sum $15,000
1.900.000 SF $0.07
190 each $100
150.000 CY $|
150.000 CY $2
150,000 CY $0.50
1,900.000 SF $0.05
3.500 LF $20
1,900.000 SF $0.05
40,000 SF $0.90
9.000 LF $20
Subtotal Construction Coot (CC)|
8%ofCC
10%ofCC
8%ofCC
Subtotal Direct Capital Cost (DCC)|
I lump sum $50,000
5% of DCC
5% of DCC
10% of DCC
15% of DCC
TOTAL CAPITAL REQUIREMENT J
PERIODIC OPERATING AND MAINTENANCE COST
Annual Maintenance for Surface Controls
Annual Groundwater Monitoring (5 wells)
5% of DCC
5 sample $3.000
$2,000
$6.000
$9,600
$12,000
$10.000
$2,800
$44,000
$20.000
$15.000
$1133.000
$19.000
$150,000
$300,000
$75,000
$95,000
$70.000
$95.000
$36.000
$180,000
$1.3100.000 |
$104,000
$130.000
$104.000
$1. 600.0001
$50.000
$80,000
$80,000
$160.000
$240,000
$2.200.000 I
$80,000
$15.000
-------
TABLE 9
PRELIMINARY COST ESTIMATE FOR SITE LF-14 PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
Semi-AnnuaJ Groundwater Monitoring (3 wells)
Quarterly Groundwater Monitoring (1 well)
Semi-Annual Storm Water Monitoring (2 locations)
5- Year Site Review
PRESENT WORTH
3
2
4
1
sample
sample
sample
lump sum -
Discount Rate
Years
$3,000
53,000
52,000
$10,000
7%
30
$9,000
$6,000
$8,000
$10,000
30-YEAR PRESENT WORTH COST | $3.800.000|
-------
TABLE 10
PRELIMINARY COST ESTIMATE FOR SITE LF-44 PREFERRED ALTERNATIVE
Item/Description
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
Surface Restoration (w/ Class HI Disposal)
Chain-Link Fencing (8 feet high. Baited)
Supervision, Health & Safety
Bid Contingency
Scope Contingency
INDIRECT CAPITAL COST
Land Use Restrictions
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
Quantity Unit
70,000 SF
1.400 LF
Subtotal Construe
8%ofCC
10% of CC
10% of CC
Subtotal Direct Capil
1 lump sum
5% of DCC
10% of DCC
15% of DCC
TOTAL CAPITAL REQ
PERIODIC OPERATING AND MAINTENANCE COST
Annual Maintenance for Institutional Controls 5% of DCC
Annual Groundwater Monitoring (2 wells) 2 sample
Semi-Annual Groundwater Monitoring (2 wells) 2 sample
Quarterly Groundwater Monitoring (1 well) 2 sample
Semi-Annual Storm Water Monitoring (2 locations) 4 sample
5-Year Sile'Review 1 lump sum
PRESENT WORTH
Discount Rate
Years
30-YEAR PRESENT WO
Unit Cost ($)
$0.08
S20
lion Cost (CC)j^
al Cost (DCC)£
$50.000
UIREMENT £j
$3,000
$3.000
$3.000
$2,000
$10.000
7%
30
RTHCOST |
ToUl Cost ($)
$5,600
$28,000
$34.000 |
$2.720
$3,400
$3,400
$44,0001
$50,000
$2,200
2(4,400
$6,600
$110.0001
$2.200
$6.000
$6.000
$6.000
$8.000
$10.000
$510,000 I
-------
TABLE 11
PRELIMINARY COST ESTIMATE FOR THE SEDA PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost {$)
DIRECT CAPITAL COST (DCC)
Construction Cost (CC):
GENERAL
Construction Trailer (Rental)
Temporary Utilities (Telephone/Power)
Decon Trailers
Health & Safety Equipment
Vehicle Decon Station
Vehicle Decon Equipment
Dust Control
Mobilization
Demobilization
SITE WORK
Clear and Grub (w/ Class III Disposal)
Soil Testing (compaction and density)
Excavate Native Soil (within 1 mile)
Haul and Dump Native Soil
Fill, Spread, and Compact Soil
General Site Grading (min. 3% slope)
Construct Drainage Channels (riprap)
Erosion Control and Revegetation
Maintain and Repair Haulage Roads
Chain-Link Fencing (8 ft high. Barbed)
6 month
6 month
6 month
6 month
2 each
6 month
6 month
1 lump sum
1 lump sum
4.000,000 SF
400 each
375,000 CY
375,000 CY
375.000 CY
4.000,000 SF
8,500 LF
4.000.000 SF
80.000 SF
14,500 LF
$500
$1,500
$2.400
$3.000
$5,000
$700
$1 1,000
$20,000
$15,000
$0.07
$100
$1
$2
$0.50
$0.05
$20
$0.05
$0.90
$20
Subtotal Construction Cost (CC)|
Supervision. Health & Safety
Bid Contingency
Scope Contingency
INDIRECT CAPITAL COST
Land Use Restrictions
Pre-Design Studies
Engineering Design Services
Construction Management
Administrative Cost (GAFB/AFCEE)
8%ofCC
10% of CC
8* of CC
Subtotal Direct Capita]
1 lump sum
5% of DCC
5% of DCC
10% of DCC
15% of DCC
Cost (DCC)|
$50,000
TOTAL CAPITAL REQUIREMENT |
$3,000
$9,000
$14,400
$18,000
$10,000
$4,200
$66.000
$20.000
$15.000
$280,000
$40.000
$375,000
$750,000
$187,500
$200,000
$170.000
$200.000
$72.000
$290,000
$2,700,000 |
$216.000
$270,000
$216.000
$3,400.000 |
$50.000
$170,000
$170,000
$340,000
$510.000
$4,600,000 [
PERIODIC OPERATING AND MAINTENANCE COST
Annual Maintenance for Surface Controls
Annual Groundwater Monitoring (9 wells)
5% of DCC
9 sample
A
$3.000
$170,000
$27,000
-------
TABLE 11
PRELIMINARY COST ESTIMATE FOR THE SEDA PREFERRED ALTERNATIVE
(Page 2 of 2) t-
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
Semi-Annual Groundwaler Monitoring (6 wells)
Quarterly Groundwater Monitoring (3 wells)
Semi-Annual Storm Water Monitoring (2 locations)
5-Year Site Review
PRESENT WORTH
6
6
4
1
sample
sample
sample
lump sum •
Discount Rate
Years
$3,000
$3,000
$2,000
$10,000
7%
30
$18,000
$18,000
$8.000
$10.000
30-YEAR PRESENT WORTH COST \ $7.8000001
-------
TABLE 12
SUMMARY OF OPERABLE UNIT 3 TPH/VOC StTE CHARACTERIZATIONS
Site
WP-17
FT-l9a
SazDpUnc RctfefuJe/Imreititaflon Results
• Some aerobic activity: indications of anaerobic activity.
• TPH, VOCi (BTEX). and chromium were detected above background.
• Vadoie zone modeling indicaied that benzene in toib will not adversely impact the
groundwater quality.
• TCE, PCE. Chloroform. I.I.I-TCA. and 1,1 -DCE detected in soil-gas.
• TPH. VOCi (BTEX), SVOCs. and 5 metals were detected above background.
• Some aerobic activity occurring; very linle anaerobic activity occuninf at the site.
• Vadoie zone modeling indicated Uul benzene in toils will not adversely impact the
froundwater quality.
Human
Health Risk *
• Cumulative Cancer Risk <
1 .06-6 (construction worker
scenario)
•Hazard Index <1.0
•Stood Lad <10
• Cumulative Cancer Risk =«
4.06-6 (construction worker
scenario)
• Hazard Index 1.0
• Blood Lead < 10
Ecological Risk
There ij no h»bitu
available for ecological
receptors; therefore, there
is no potential ecological
risk.
There is no habitat
available for ecological
receptors: therefore, there
is no potential ecological
risk.
FT-19b . Various constituents delected in soil-gas.
• TPH, VOCs. SVOCs. and 6 metals were delected above background.
• Test pit excavations revealed that medical wastes were primarily in the surf*
; soils.
• Cumulative Cancer Risk » There is no habitat
5.2E-6 (industrial/ available for ecological
commercial worker scenario) receptors: therefore, there
• Hazard Index < 1.0 » no P<«»««' ecological
•Blood Lead < 10
risk.
FT-19C •TCE.PCEChloroform.and l.l.I-TCAdetectedmtoil-g«.
• TPH. VOCs (BTEX and TCE}. SVOCs. and 11 metals detected above background.
• Some aerobic activity occurring: very little anaerobic activity occurring at the site.
• Vadoie zone modeling indicated thai TCE in soils may migrate to the groundwater in
75 yean if untreated.
• Cumulative Coxa Risk »
3.1E-6 (industrial/
commercial worker scenario)
•Hazard Index < 1.0
• Blood Lead < 10
There is no habiut
available for ecological
receptors: therefore, there
is no potential ecological
risk.
FIXZOfsoil) « TCE detected in soil-gas.
• TPH. TRPHs. and seven metals detected above background in soil samples. No TCE
detected.
• inorganics below or near background were detected iBdowngradiem groundwater,
• Vadose zone modeling indicated thai contaminants detected at the site do not pose a
threat to groundwater.
• Cumulative Cancer Risk <
4.0E-S (industrial/
commercial worker)
•Hazard Index< 1.0
• Blood Lead < 10
There is no habitat
available for ecological
IfiCtpliil 4i tnCTCiOCCt tACfV
is no potential ecological
risk.
OT-Sl
SS-59
• No COPCs were detected in samples collected from the soil berm at Facility 807.
• TPH and BTEX detected in samples collected from the soil berm at Facility 799 from
10 to 1 20 feel bgs. Concentration! exceeded the screening criteria.
• TPH detected in samples collected from the engine less cells.
• TPH and BTEX were detected in crougradient groundwaier samples, but were noi
drtrrted in downgradient samples.
• Groundwater Modeling indicaied that benzene may migrate approximately 400 feet
from the source area in SO yean.
• TPH delected in groundwaier samples from two wells installed in the hot spot.
• TPH constituents detected in soil samples at concentralions exccedinc the screenini
• Preliminary screening
indicated thai the site does
not pose a risk because the
confirmed contamination is
at depths that would not
affect receptors in the risk
assessment scenarioc.
Therefore, a risk assessment
calculation was not
performed.
•Blood Lead < 10
See Site OT-Sl.
There is no habiut
available for 'ecological
receptors; therefore, there
is no potential ecological
risk.
There is no habitat
available for ecological
receptors: therefore, there
is no potential ecological
risk.
OT-69 -TCEand PCE detected above MCLsin groundwater.
• PCE not detected in soil samples: TCE detected in small percentage of soil samples.
• Highest levels of TCE will attenuate to 5 ug/L ia 4O to 45 years.
• TCE limited to the upper 30 feet of the aquifer.
• Total volumes of TCE = 0.8 gallons and PCE * 0.006 gallons.
• Total carcinogenic risk =
2E-05. No likely exposure
pathways to on-base workers
and off-base residents.
•Hazard Index < 1.0
• Blood Lead - not
applicable
Because the site is
comprised of
groundwaier, there is no
completed exposure
pathway for ecological
receptors.
Notes:
a Highest cancer risk from all scenarios evaluated and the scenario under which the highest risk was calculated is presented.
-------
TABLE 13
NUMERICAL CLEANUP STANDARDS FOR TPH/VOC GROUNDWATER SITES
Federal
Suggested
Concentration to
Meet Secondary
Constituent
*
Benzene
Ethylbcnzene
Toluene
Trichloroethene (TCE)
Tetrachloroethene (PCE)
Xylenes
••"•"
MCL
— •— ^— *•-
5
700
1,000
5
5
10,000
SMCL
—••*•—— ^•••—-B
NA
30
40
NA
NA
20
ii»
MCL
1
700
150
5
5
1,750
1 '" .
w» a»«w
SMCL
-
NA
NA
NA
NA
NA
NA
aM\*Li ui J
Odor Units
•^ — — •^— — _
NA
29
42
NA
NA
17
Cleanup
Standard
1
29
40
5
5
17
MCL = maximum contaminant level
NA = not applicable
SMCL =s secondary maximum contaminant level
Note: All concentrations are presented in pg/L.
Source: "A Compilation of Water Quality Goals," California RWQCB, Central Valley Region (RWQCB, 1995).
-------
tit
TABLE 14
SUMMARY OF DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES FOR OU 3 TPH/VOC SITES
Alternative
Applicable
Sites
Protection of
Human Health
and the
Environment
Compliance with
ARARs Effectiveness Reduction of TMV Implementability
Total Cost
6. No Action for Soil
7. Removal/Disposal
9. Bioventing
10. No Action for
Groundwatcr
I!. Oxygen Enhanced
Bioremediation
WP-17.FT- Does not reduce Does not comply. Not effective.
19a, FT-19b, potential for future
FT-l9c.FT-20 exposure.
(soil),OT-5l.
SS-59
FT-20(soil),
SS-59
8. Soil Vapor Extraction FT-l9c
WP-17.FT-
!9b.OT-5l
OT-51
OT-51
Reduces potential Complies with Effective.
for future exposure ARARs.
Significantly Complies with Effective.
reduces potential ARARs.
for future
exposure.
Significantly Complies with Effective.
reduces potential ARARs.
for future
exposure.
Does not reduce Does not comply. Not effective.
potential for future
exposure.
Significantly Complies with
reduces potential ARARs.
for future
exposure.
Effective.
No reduction of TMV. No technical See Table 16.
limitations.
Significant reduction of Easily implemented. See Table 16.
TMV through removal.
treatment, and disposal
of contaminated soils.
Significant reduction of Easily implemented. See Table 16
TMV.
Significant reduction of Easily implemented. See Table 16
TMV.
No reduction of TMV. No technical See Table 16.
limitations.
Significant reduction of Easily implemented. See Table 16
TMV.
ARARs - applicable or relevant and appropriate requirements
TMV - toxicily, mobility, or volume
-------
I
Source
Porter-Cologne Water
Quality Control Act
(California Water Code)
Porter-Cologne Water
Quality Control Act
(California Water Code)
Porter-Cologne Water
Quality Control Act.
California Water Code
Sections 13000,13140.
13240
Porter-Cologne Water
Quality Control Act,
California Water Code
Sections 13140,13240,
13304. 13307
TABLE 15
ARARs FOR GAFB OU 3 TPH/VOC
SITES WP-17, FM9a, FM9b, FT-lfc, OT-51, AND OT-69
(Pace 1 of 9)
Standard, Requirement,
Criterion, or Limitation' ARAR Status*
Description
California Water Code
9 13176
California Water Code
5 13750.5
Slate Water Resources
Control Board Resolution
68-16 Statement of Policy
with Respect to
Maintaining High Qua|j|y
of Waters of the Slate
(Resolution 68-16)
55 land 2
State Water Resources
Control Board Resolution
92-49 (as amended)
Policies and Procedures
for Investigation and
Cleanup and Abatement of
Discharges Under WflKr
Code Section I33Q4
(Resolution 92-49)
§ HI G.
Applicable Requires data analysis to be performed in a State certified laboratory.
Potentially applicable to cleanup alternatives involving sampling.
Applicable Requires well drillers to possess a C-57 license.
Potentially applicable to cleanup alternatives involving installation of wells.
See Description The resolution establishes requirements for activities involving discharges of contamination
directly into surface waters or groundwater (e.g., quality of pump and treat effluent into
surface waters or groundwater).
The Air Force and the State of California have not agreed whether State Water Resources
Control Board Resolution No. 68-16 is an ARAR for the remedial action at any of the OU 3
sites. Therefore, this FS does not identify the requirement as an ARAR for the remedial
action. The State asserts that the requirement is an ARAR. and that it requires soil
remediation where a discharge impacts or threatens to impact the beneficial uses of waters of
the State. The State has decided not to invoke dispute resolution because the proposed action
will address threatened impacts to waters of the State.
See Description The USAF and USEPA agree that Resolution No. 92-49, Section I1I.G. is an ARAR for
purposes of the OU 3 RI/FS with respect to groundwater remediation at all groundwater sites
and the soil remediation at OT-51 and FT-19. The USAF contends, for purposes of this
RI/FS, that Section 1H.G. is a "relevant and appropriate" requirement. The Slate contends
Section III.G is an "applicable" requirement. The cleanup standards set forth in Table 13
satisfy (he requirements of SWRCB Resolution 92-49.
-------
Source
TABLE IS
ARARs FOR GAFB OU 3 TPH/VOC
SITES WP-17, FT-19a, FT-19b, FT-19c, OT-51, AND OT-69
(Page 2 of 9)
Standard, Requirement,
Criterion, or Limitation' ARAR Status'
Description
Porter-Cologne Water
Quality Control Act,
California Water Code
Sections 13240,13241,
13242.13243,13382
Porter-Cologne Water
Quality Control Act,
California Water Code
Sections 13240,13241,
13242. 13243, 13382
Federal Safe Drinking Water
Act, 40 CFR Part 141,
Subpari G or California
Hazardous Waste Control
Law.22CCR
Water Quality Control
Plan for the Lahontan
Region (Basin Plan)
effective March 31,1995
Table 2-2. Beneficial Uses
for Groundwater of the
Lahontan Region,
Department of Water
Resources Basin No. 6-42,
Upper Mojavc River
Valley, page 2-46
Basin Plan
Water Quality Objectives
for Groundwatcrs, page 3-
2,3-12. and 3-13
40 CFR 141.61 or
Table 64444-A-
Maximum Contaminant
Levels - Organic
Chemicals
Applicable
Applicable
Relevant and
Appropriate
The beneficial uses of ground waters beneath GAFB are defined as:
a) Municipal;
b) Agricultural;
c) Industrial;
d) Fresh Water Replenishment; and '
e) Aquaculture,
Potentially applicable to alternatives addressing groundwater contamination at Sites OT-51
and OT-69.
The water quality objectives that apply to affected ground waters are for: Coliform Bacteria.
Chemical Constituents, Radioactivity, and Taste and Odor. Compliance will consider other
potential ARAR standards such as State and Federal MCLs. Potentially applicable to
alternatives addressing groundwater contamination at Sites OT-51 and OT-69 The cleanup
standards for this ROD are set forth in Table 13.
Primary MCLs for organic constituents which are contaminants of concern at the Site. State
MCLs which are more stringent than the Federal MCLs, or not addressed by Federal MCLj,
and therefore potentially ARARs are: benzene, toluene, and xylene. Potentially relevant and
appropriate to remedial alternatives addressing groundwater at Sites OT-51 and OT-69 The
cleanup standards for this ROD are set forth in Table 13.
-------
I
TABLE 15
Source
ARARi FOR GAFB OU 3 TPH/VOC
SITES WP-17, FT-19., FW», FT.19c, OT-S1, AND OT-69
(Page 3 of 9)
Standard, Requirement,
Criterion, or U mttation' ARARSutusk
CSDWA
Table 64449-A-
Secondary Maximum
Contaminant Levels,
Consumer Acceptance
Limits
Table 64449-B-
Secondary Maximum
Contaminant Levels -
Ranges
Relevant and Defines secondary maximum contaminant levels (SMCLs)
Appropriate Potentially rckvam ^d appropriate to remedial alternatives addressing groundwater at Sites
'"?•' *f ^ L° d'SagrcC"language has bcen estob«*«l between the Air Force and
"The State asserts that the narrative taste and odor water quality objective specified in the
Water Quality Control Plan for Lahontan Regional Water Quality Control Board which
incorporates state primary and secondary drinking water standards, is an ARAR that applies to
the esubhshment of cleanup levels at this OU. The Air Force agrees that the narrative taste
and odor water quality objective is an ARAR. but does not agree that the secondary odor
standard of three odor units is an ARAR because the measurement is subjective based upon
the sensory determination of a panel. The Air Force agrees to implement the taste and odor
objectwe for toluene, ethylbenzene. and xylenes by using the numeric taste and odor standards
proposed by USEPA, but not promulgated, as to be considered standards that will be
identified as performance standards in this ROD. The numeric values in Table 13 reflect this
agreement The Air Force also agrees to evaluate compliance with the three odor unit
objective, based on appropriate standard protocols, e.g., EPA Method 140 or Standard
Methods for the Examination of Water and Wastewater, in determining whether the remedial
action is complete. The State reserves its right to dispute, according to the terms of the
Federal Facility Agreement, whether the Air Force has achieved compliance with the taste
and odor objective in the Water Quality Control Plan »
-------
(»*•
TABLE 15
ARARs FOR GAFB OU 3 TPH/VOC
SITES WP-17, FT-lJi, FT-19b, FT-19c, OT-51, AND OT-«9
(Page 4 of 9)
Source
Standard, Requirement,
Criterion, or Limitation' ARAR Status*
Description
Basin Plan
Water Quality Objectives for
Groundwaters, page 3-2 and
3-12
Porter-Cologne Water
Quality Control Act (Porter
Cologne Act), California
Water Code Sections 13140
-13147.13172.13260,
13263,13267.13304
Discharges of Waste to
Land. Title 23. Chapter 15,
California Code of
Regulations (Chapter IS)
Porter-Cologne Act
Chapter IS
Porter-Cologne Act
Chapter IS
Porter-Cologne Act
Chapter IS
Memorandum titled
"Beneficial Use-Protective
Water Quality Limits For
Components of Petroleum-
Based Fuels", dated 17
May 1995 (replaces
memoranda dated 3/26/90,
1/14/91,7/6/92,5/13/93,
and 1/18/95)
Central Valley Regional
Water Quality Control
Board- Jon Marshack
§25ll(d)
J2550.l(a)(4)
§ 2SS0.4
J 2550.10
To Be
Considered
Applicable
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Provides beneficial use protective water quality limits for components of petroleum based
fuels.
ments
Exempts actions taken by or at the d,rection of public agencies from Chapter IS requirements
providedI wastes removed are discharged in accordance with Chapter 15. Article 2 and walS
contained implement Chapter IS requirements to the extent feasible
Requires monitoring performance of selected remedial alternative.
Potentially relevant and appropriate to remedial alternatives addressing groundwater
contamination (Sites OT-51 and OT-69).
Concentration Limits (CL) - Must be established for groundwater. surface water, and the
unsaturated zone. Must be based on background, equal to background, or for corrective
actions, may be greater than background (CLGTB), not to exceed the lower of the MCL or
the concentration technologically or economically achievable (Sites OT-51 and OT-69).
Specifies requirements for ground water remedial action to ensure that the water quality
pr«ect,on standard ,s achieved throughout the zone affected by the release including but not
hunted to, source control measures and monitoring 'nc.uamg. but not
-------
ARARi FOR GAFB OU 3 TPH/VOC
SITES WP-17, FT-19», FT-19b, FT-19c, OT-51, AND OT-
-------
i,E 15
ARARs FOR GAFB Ol) 3 TPH/VOC
SITES WP-17, FT-19a, FT-19b, FT-19c, OT-51, AND OT-69
(Page 6 of 9)
Source
Standard, Requirement,
Criterion, or Limitation* ARAR Status*
Description
Drilling, Coring, To Be
Sampling and Logging at Considered
Hazardous Substances
Release Sites
Monitoring Well Design To Be
and construction for Considered
Hydrogeological
Characterization
Representative Sampling To Be
of Ground Water for Considered
Hazardous Substances
Ground Water Modeling To Be
for Hydrogeological Considered
Characterization
Provides minimum construction and destruction criteria for water wells, monitoring wells,
and cathodic protection wells. Also includes criteria for borehole abandonment
Federal Safe Drinking
Water Act
Federal Clean Water Act 40
CFR122
40CFR144-
Underground Injection
Control Program
USBPA Administered
Permit Programs:
National Discharge
Elimination System 40
CFR122-26
Applicable Establishes substantive requirements for actions that involve injection of fluids into
subsurface through wells. The injection cannot cause a violation of primary MCLs, must be
maintained, must be monitored, and injection cannot take place until the well construction is
complete.
Applies to cleanup of OT-51.
Applicable Requirements ensure stormwater discharges from remedial action activities do not violate
surface water quality standards. To comply with this requirement, the US AF must comply
with the requirements contained in the State General Industrial Storm Water Permit (Order
No. 91-13-DWQ, as amended by Order No. 92-12-DWQ, NPDES CAS000001).
-------
ARARs FOR GAFB OU 3 TPHAVOC
SUES WP-17, FT.19*, FT.lSfc, FM9c, OT-5I, AND OT-69
Sourc*
Federal Clean Water Acl
40CFRPart264.SubpartB
(General Facility
Standards), as delegated to
the State and implemented
through Hazardous Waste
Control Law (HWCL) TiUe
22 Social Security, (22
CCR) Division 4.5.
(Environmental Health .
Standards for the
Management of Hazardous
Wastes), Chapter 11,
Articles 1-5, Chapter 12
(Standards Applicable to
Generators of Hazardous
Waste) and Chapter 14
(Standards for Owners and
Operators of Hazardous
Waste Transfer, Treatment,
Storage, and Disposal
Facilities), Articles 2
Stiadanl, Requirement,
Criterion, or Limitation* ARAR Status*
40CFR 5122.41(d),
122.41 (e), and 122.44(d)
40 CFR 5264.13
22 CCR $66262.11
22 CCR 566262.13
40 CFR 5264.14
22 CCR 566262.14
40 CFR 5264.15
22 CCR 566262.15
f
likelihood of causmg adverse impacts on surface water quality
*«•***»» «-« beproperiy operated and
Applicable
0rt0min^
Potentially applicable to cleanup alternatives at facilities which involve on-site treatment.
storage, or d,sposal of hazardous waste (i.c, investigation derived waste [1DWJX
-------
15
ARARs FOR GAFB OU 3 TPH/VOC
SITES WP-17, FT-19a, FT-19b, FM9c, OT-51, AND OT-69
(Page 8 of 9)
Source
Standard, Requirement,
Criterion, or Limitation*
ARAR Status'
Description
40 CFR Part 264, Subpart C
(Preparedness and
Prevention) as delegated to
the State and implemented
through HWCL 22
CCR, Division 4.5, Chapter
14, Ankle 3 (Preparedness
and Prevention)
40 CFR Part 264, Subpart D
(Contingency Plan and
Emergency Procedures) as
delegated to the State and
implemented through
HWCL 22
CCR, Division 4.5, Chapter
14, Article 4 (Contingency
Plan and Emergency
Procedures)
40 CFR Part 264, Subpart 1
(Use and Management of
Containers) as delegated to
the State and implemented
through HWCL 22 CCR,
Division 4.5, Article 9 (Use
and Management of
Containers
40 CFR 55 264.31-34
22 CCR 55 66264.31-34
40 CFR 55 264.51-
264.53.(a) and 264.55
22 CCR 5566264.51-
53(a) and 66264.55
40 CFR 55 264.171-
264.178
22 CCR 55 66264.171
66264.178
Applicable or Requires that hazardous waste TSD facilities be designed, constructed, operated and
Relevant and maintained to minimize the possibility of fire, explosion, or release of hazardous waste (40
Appropriate CFR 5 264.31 and 22 CCR 566264.31).
Potentially applicable or relevant and appropriate to cleanup alternatives at facilities which
involve on-site treatment, storage, or disposal of hazardous waste (i.e., IDW).
Applicable or Requires development and, if appropriate, implementation of a contingency plan to minimize
Relevant and hazards to human health or the environment from fire, explosion, or release of hazardous
Appropriate substances (40 CFR 1264.51 and 22 CCR §66264.51).
Plan must contain certain items (40 CFR 5264.52 and 22 CCR 566264.52).
Plan and emergency coordinator must be on-site (40 CFR 55 264.53.(a) and 264.55; 22 CCR
§566264.53(3) and 66264.55).
Potentially applicable or relevant and appropriate to cleanup alternatives at facilities which
involve on-site treatment, storage, or disposal of hazardous waste (i.e., IDW).
Applicable or Requires that containers used for storage be in good condition (40 CFR § 264.171 and 22
Relevant and CCR 566264.171).
Appropriate Requires that containers used for storage be compatible with the hazardous substance (40
CFR 5 264.172 and 22 CCR 566264.172).
Requires proper management of containers during storage and handling (40 CFR 5 264.173).
Requires inspections of containers used to store hazardous substances (40 CFR 5 264.174
and 22 CCR 566264.174).
Requires adequate secondary containment for stored hazardous waste, as specified (40 CFR
5 264.175 and 22 CCR 566264.175).
Requires isolating stored, ignitable waste (40 CFR 5 264.177 and 22 CCR 566264.177).
Requires removal of stored hazardous waste at closure of the TSD hazardous waste facility
(40 CFR 5 264.178 and 22 CCR 566264.178).
Potentially applicable or relevant and appropriate to cleanup alternatives at treatment,
storage, or disposal facilities which store hazardous waste on-site (e.g., IDW).
-------
ARARs FOR GAFB OU 3 TPH/VOC
SITES WP.17, FT-19., FM9b( FT-19C, OT-51, AND OT-
-------
; 16
SUMMARY OF REMEDIAL ALTERNATIVE COSTS FOR OU 3 TPWVOC SITES
Site
WP-I7
FT-19.
FT-19b
FT-JJc
FT-20(sotl)
OT-51
(soil)
OT-51
(groundwater)
SS-59
Cost Criteria Alternative 6 Alternative? Alternatives Alternative 9 Alternative 10 Alternative 11
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present- Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30-Year Present- Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30-Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30-Year Present- Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present-Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30- Year Present- Worth Cost
Construction Cost
Direct Capital Cost
Total Capital Requirement
30-Year Present-Worth Cost
$8.800
$12.900
$14,800
$110.000
$0
$0
$0
$170,000
$0
$0
$0
$170,000
$0
$0
$0
$170,000
$0
$0
$0
$170.000
$16,600
$24.200
$27,000
$280,000
NA
NA
NA
NA
$8.800
$12.900
$14.800
$110.000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$27,600
$40,300
$52.800
$52,800
NA
NA
NA
NA
NA
NA
NA
NA
$28,200
$41.200
$54,000
$54,000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$199,500
$326.900
$444.000
$680,000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$46.400
$73.100
$107.000
$270.000
$228,480
$369,900
$501.000
$780.000
$40.600
$64,600
$95.000
$250.000
NA
NA
NA
NA
NA
NA
NA
NA
$182.900
$280.700
$383.000
$660.000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$0
$0
$0
$250.000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$3.500
$6,500
$62,000
$280,000
NA
NA
NA
NA
NA - not applicable
-------
TABLE 17
PRELIMINARY COST ESTIMATE FOR SITE WP-17 PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
DIRECT CAPITAL COSTS (DCC) '
Equipment Costs (EC)
Aboveground collection Piping (2-inch PVC)
Bioventing Blower (IS horsepower)
Valve/gauge
Construction Costs (CC)
Surface Repair/Preparation
Extend Power from Bldg. 551 or 552
Fence
Visquecn
Pea Gravel
Vents and Monitoring Point Borings
Equipment Pad
Analytical
Mechanical
Instrumentation
Electrical
Supervision, Health & Safety
Bid Contingency
Scope Contingency
Contractors Overhead and Profit
INDIRECT CAPITAL COSTS
Treatability Study
Engineering Design Services
Construction Management
Administration Costs {GAFB/AFCEE)
Final O&M Manuals
Quantity Unit
30 linear foot
1 each
3 each
1 lump sum
1 lump sum
40 feet
4,800 square feet
20 cubic yards
1 lump sum
1 lump sum
! lump sum
40% of EC
10% of EC
20% of EC
8% of CC
10%ofCC
8%ofCC
20% of CC
Subtotal Direct Capital
lump sum
6% of DCC
10% of DCC
15% of DCC
2% of DCC
Unit Cost ($)
$30
$4.000
$150
Subtotal EC
$3,000
$2.500
$20
$2
$90
$15,864
$2,500
Subtotal CC
Cost* (DCC)
TOTAL CAPITAL REQUIREMENT)
Total Cost ($)
$900
$4.000
$450
$5.350
$3.000
$2,500
$800
$9,600
$1,800
$15,864
$2.500
$1.243
$2,140
$535
$1.070
$46,402
$3,7112
$4 MO
«^*T(»^rw
$3.712
$9,280
$73,096
$9.455
$4,386
$7,310
$10,964
$1,462
$107,000 1
PERIODIC OPERATING AND MAINTENANCE COSTS '
Bioventing (Years 1-3)
Energy
Labor
Maintenance Materials
10,000 kW-hr
250 hours
5% of EC
$0.10
$60
$1,000
$15.000
$268
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TABLE 17
PRELIMINARY COST ESTIMATE FOR SITE WP-17 PREFERRED ALTERNATIVE
(Page 2 of 2).
Item/Description
Quarterly Ground water sampling (1 well)
Demobilization (Year 3)
System Demolition
Vent/Well Abandonment
Site Closure Analyses
Confirmation Sampling (Year 5)
Boring Installation ( 1 boring)
Analytical
5- Year Site Review
PRESENT WORTH
Quantity
4
1
7
1
1
1
1
Unit
sample
lump sum
each
lump sum
lump sum
lump sum
lump sum
Discount Rate
Years
TOTAL PREI
Unit Cost ($)
$3,000
Subtotal
$20.000
$3.000
$45.000
Subtotal
$4.892
$1.388
Subtotal
$5.000
7%
5
SENTWORTH[
Total Cost ($)
$12.000
$28.268
$20.000
$21.000
$45.000
$86,000
$4.892
$1.388
$6,280
$5.000
$270.000 |
Assumptions:
1 After 3 year estimated cleanup time, there will be closure on the site and no continued monitoring.
2 One injection vent and 6 monitoring points will be installed as part of bioventing system.
3 One confirmation boring will be installed to a depth of 80 feet at the hot spot at the end of year 3. Five samples will
be collected from the boring.
-------
TABLE 18
PRELIMINARY COST ESTIMATE FOR SITE FT-19. PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
DIRECT CAPITAL COSTS (DCC)
Equipment Coots (EC)
Quantity Unit Unit Cost ($) Total Coat ($)
»u~>i.giuuiiu coiiccuon ripmg (2-incn PVC
Biovcnting Blower (5 horsepower)
Valve/gauge
Construction Costs (CC)
Surface Repair/Preparation
Extend power from OU I Treatment System
Fence
Vjsqueen
Pea Gravel
Vents and Monitoring Point Borings
Equipment Pad
Analytical
Mechanical
Instrumentation
Electrical
Supervision, Health
-------
TABLE 18
PRELIMINARY COST ESTIMATE FOR SITE FT-19* PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Quantity Unit
Unit Cost ($) Total Cost ($)
Maintenance Materials
Quarterly Groundwater Sampling (2 wells)
5% of EC
sample
$3,000 _
Subtotal
$1,818
$24,000
$44,148
Demobilization (Year 5)
System Demolition
Vent/Well Abandonment
Site Closure Analyses
Confirmation Sampling (Year S)
Boring Installation (4 borings)
Analytical
5- Year Site Review
PRESENT WORTH
1 lump sum
14 each
1 lump sum
1 lump sum
1 lump sum
lump sum
Discount Rate
Years
$20,000
$3,000
$45.000
Subtotal
$12.858
$4.484
Subtotal
$5.000
7%
5
$20,000
$42,000
$45,000
$107,000
$12,858
$4,484
$17341
$5.000
TOTAL PRESENT WORTH! $780,000 \
Assumptions:
1 After S year estimated cleanup time, there will be closure on the site and no continued monitoring.
2 Six injection vents and 9 monitoring points will be installed as part of bioventing system.
3 Three confirmation borings (one at each hot spot) will be installed each to a depth of 115 feet at the end of year 5.
Five samples will be collected from each boring.
-------
TABLE 19
PRELIMINARY COST ESTIMATE FOR SITE FT-19c PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
Quantity Unit Unit Cost ($) Total Cost ($)
uiKfcl 1 CAPITAL COSTS (DCC)
Equipment Costs (EC)
Aboveground Collection Piping (2-inch PVC)
SVE Blower ( 10 horsepower)
Valve/gauge
Construction Costs (CC)
Surface Repair/Preparation
Extend power from FT-19a treatment unit
Fence
Visqueen
Pea gravel
Vents and Monitoring Point Borings
Equipment Pad
Analytical
Mechanical
Instrumentation
Electrical
Supervision. Health & Safety
Bid Contingency
Scope Contingency
Contractors Overhead and Profit
INDIRECT CAPITAL COSTS
Treatability Study
Engineering Design Services
Construction Management
Administration Costs (GAFB/AFCEE)
Final O&M Manuals
400 linear foot $30 $12,000
1 each $20,000 $20.000
24 «!ach $150 $3.600
Subtotal EC $35,600
1 lump sum $3,000 $3.000
1 lump sum $10,000 $10.000
40 feet $20 $800
20,000 square feet $2 $40,000
380 cubic yards $90 $34.200
1 lump sum $45.945 $45,945
1 lump sum $2.500 $2,500
1 lump sum $2,524
4°* °f EC $,4,240
10% of EC $3,560
20% of EC $7,120
Subtotal CC $199.489
8% of CC $15,959
IO%ofCC $19,949
8%ofCC $15,959
20%ofCC $39.898
Subtotal Direct Capital Costs (DCC) $326,854
lump sum $9,455
6% of DCC $i9,6n
10% of DCC $32.685
15% of DCC $49,028
2% of DCC $6437
loi ALLAPiiAL REQUIREMENT) $444.000 |
PERIODIC OPERATING AND MAINTENANCE COSTS
SVE (Years 1-5)
S£f 67.000 kW-hr $0.10 $6.700
., . 250 hours $60 Sisnnn
Mamtcnance Materials 5%ofEC *" »*«»
-------
TABLE 19
PRELIMINARY COST ESTIMATE FOR SITE FT-19c PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Quantity Unit Unit Cost ($) Total Cost {$)
Quarterly Groundwater Sampling (2 wells)
sample
$3,000 _
Subtotal'
$3,000
$26,480
Demobilization (Year 5)
System Demolition
Vent/Well Abandonment
Site Closure Analyses
Confinnation Sampling (Year 5)
Boring Installation (4 borings)
Analytical
5- Year Site Review
PRESENT WORTH
1 lump sum
19 each
1 lump sum
1 lump sum
I lump sum
1 lump sum
Discount Rate
Years
$20,000
3,000
$45,000
Subtotal
$16.142
$9.368
Subtotal
7%
5
$20,000
$57.000
$45,000
$122.000
$16,142
$9,368
$25,510
$5.000
TOTAL PRESENT WORTHJ $680.000 I
Assumptions:
1 After 5 year estimated cleanup time, there will be closure on the site and no continued monitoring.
2 Seven injection vents and 12 monitoring points will be installed as part of SVE system.
3 Four confirmation borings (one at each hot spot) will be installed each to a depth of 115 feel at the end of year 5.
Five samples will be collected from each boring.
-------
TABLE 20
PRELIMINARY COST ESTIMATE FOR SITE OT-SI SOILS PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
Quantity Unit Unit Cost ($) Total Cost ($>
DIRECT CAPITAL COSTS (DCC)
Equipment Costs (EC)
Aboveground collection Piping (2-inch PVC)
Bioveniing Blower (5 horsepower)
Valve/gauge
Construction Costs (CC)
Downgradiem Monitoring Well Installation
Surface Repair/Preparation
Extend power from OU 1 Treatment System
PWru*A
j^ncc
Visqucen
Pea Gravel
Vcnis and Monitoring Point Borings
Equipment Pad
Analytical
Mechanical
Instrumentation
Electrical
Supervision, Health & Safety
Bid Contingency
Scope Contingency
Contractors Overhead and Profit
INDIRECT CAPITAL COSTS
Treatability Study
Engineering Design Services
Construction Management
Administration Costs (GAFB/AFCEE)
Final O&M Manuals
30 linear foot
1 each
12 each
2 lump sum
1 lump sum
1 lump sum
40 feet
4.800 square feet
20 cubic yards
1 lump sum
1 lump sum
1 lump sum
40% of EC
10* of EC
20% of EC
8%ofCC
10%ofCC
8% of CC
20%ofCC
$30 $900
$11.000 $11.000
$150 $1,800
Subtotal EC $13,700
$16,605 $16,605
$3.000 $3,000
$75.000 $75.000
$20 $800
$2 $9,600
$90 $1,800
$45.113 $45.113
$2,500 $2,500
$5.151
$5.480
$1,370
$2.740
Subtotal CC $182.859
$14,629
$18.286
$14,629
$36.572
Subtotal Direct Capital Costs (DCC) $280,674
lump sum
6% of DCC
10% of DCC
15% of DCC
2% of DCC
$9,455
$16,840
$28,067
$42 1O1
«*•**» * VI
$5.613
TOTAL CAPITAL REQUIREMENT! $383.000 1
PERIODIC OPERATING AND MAINTENANCE COSTS : '
Bioventing (Years 1-5)
Energy
¥ 1.
Labor
Maintenance Materials
16.700 IcW-hr
250 hours
5% of EC
$0.10 $1,670
$60 $15000
***"* «*• I •*« VvV
$685
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TABLE 20
PRELIMINARY COST ESTIMATE FOR SITE OT-51 SOILS PREFERRED ALTERNATIVE
(Page 2 of 2)
Item/Description
Quantity Unit Unit Cost ($) Total Cost ($)
Quarterly Groundwater Sampling (2 wells)
Demobilization (Year 5)
System Demolition
Vent/Well Abandonment
Site Closure Analyses
Confirmation Sampling (Year 5)
sample
1 lump sum
10 each
1 lump sum
$3.000
Subtotal"
$20,000
$3,000
$45,000 _
Subtotal
$24.000
$41,355
$20,000
$30,000
$45.000
$95,000
Boring Installation (4 borings)
Analytical
5- Year Site Review
PRESENT WORTH
1 lump sum
i lump sum
lump sum
Discount Rate
Years
$16.652
$5.305
Subtotal
7%
5
$16.652
$5,305
$21,957
$5,000
TOTAL PRESENT WORTHl $660.000
Assumptions:
1 After 5 year estimated cleanup time, there will be closure on the site and no continued monitoring.
2 Four injection vents and 6 monitoring points will be installed as pan of bioventing system.
3 Four confirmation borings will be installed each to a depth of 120 feet at the end of year 5. Five
samples will be collected from each boring.
4 Installation of two 135-foot downgradient monitoring wells would be required to satisfy
long-term monitoring requirements.
-------
TABLE 21
PRELIMINARY COST ESTIMATE FOR SITE OT-51 GROUNDWATER PREFERRED ALTERNATIVE
(Page 1 of 2)
Item/Description
Quantity Unit Unit Cost ($) Total Cost ($)
Initial Equipment Costs (ffiC)
ORC Filler Sock Canister
Periodic Equipment Costs (PEC)
ORC filter socks (3 wells. 10 feet each)
Shipping for ORC filter socks
Construction Costs (CC)
Installation of ORC
Mobilization
Demobilization
Supervision. Health & Safety
Bid Contingency
Scope Contingency
Contractors Overhead and Profit
•
INDIRECT CAPITAL COSTS
Land Use Restrictions
Administration Costs (GAFB/AFCEE)
Engineering Design Services
Final O&M Manuals
PERIODIC OPERATING AND MAINTENANCE
Annual Groundwater Monitoring {4 wells)
Semi-Annual Groundwater Monitoring (4 wells)
Quarterly Groundwater Monitoring (2 wells)
Semi-Annual ORC sock replacement (years 1-3)
5- Year Site Review
PRESENT WORTH
30 feet
30 feet
138 Ibs
1 lump sum
1 lump sum
1 lump sum
8% of CC
10%ofCC
8% of CC
20%ofCC
Subtotal Direct Capita
1 lump sum
I lump sum
6%ofDCC
2% of DCC
TOTAL CAPITAL REQ
COSTS
4 sample
4 sample
4 sample
2 each
1 lump sum
Discount Rate
Years
$11 $330
subtotal IEC $330
$32.50 $975
$0.27 $37
subtotal PEC $1.012
$2400 $2.500
$500 $500
$500 $500
Subtotal CC $3.500
$280
$350
$280
$700
1 Costs (DCC) $6,452
$50.000 $50.000
$5.000 $5.000
$387
$129
fUlREMENTf $62.000 J
$3,000 $12.000
$3.000 $12,000
$3,000 $12.000
$6.122 $12.245
$5,000 $5.000
,— —
7%
5
TOTAL PRESENT WORTH["1280000""]
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TABLE 21
PRELIMINARY COST ESTIMATE FOR SITE OT-51 GROUNDWATER PREFERRED ALTERNATIVE
(Page 2 of 2)
Assumptions:
1 Oxygenation of upper portion of aquifer would be accomplished with system to be installed to remediate soils
and the use of oxygen release compound (ORC) in the top 10' of groundwater in the 3 existing monitoring wells.
2 Installation of ORC will require a 2 person crew for 2 days.
3 Source removal will be achieved through the use of a bioventing system.
4 ORC socks will be replaced every 6 months for 3 years starting at the end of the first 6 months.
5 Filter sock canister is reusable. They prevent socks from getting stuck in wells once spent.
6 Spent ORC socks can be disposed of in a sanitary landfill.
7 Groundwaier cleanup will be achieved in 3 years. Groundwater monitoring will continue through year 5.
-------
TABLE22
SUMMARY OF DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES FOR SITE OT-69
Alternative
G-l No Action.
Protection of
Human Health and
the Environment Compliance
wfthARAto Effectiveness
Does not reduce Complies with Effective.
existing potential for ARARs.
future exposure.
G-2 Natural Attenuation/Institutional Reduces potential for Complies with Effective.
Controls future exposure ARARs.
G-3 In Situ Air Sparging, SVE Significantly reduces Complies with Effective
Recovery/Abatement in Vadose potential for future ARARs.
Zone, Groundwater Monitoring, exposure.
G-4 Groundwater Extraction, Surface Significantly reduces Complies with Effective
Groundwater Treatment with potential for future ARARs.
UV-Oxidalion, Reinjection of exposure.
Treated Groundwater.
G-5 Groundwater Extraction, Surface Significantly reduces Complies with Effective
Groundwater Treatment with potential for future ARARs.
GAC, Reinjeciion of Treated exposure.
Groundwater.
G-6 Groundwater Extraction. Surface Significantly reduces Complies with Effective
Groundwater Treatment with potential for future ARARs.
Thermally Abated Air Stripping, exposure.
Reinjection of Treated
Groundwater.
* Present worth with 7% discount rate.
ARAR - applicable or relevant and appropriate
TMV - toxicity, mobility, or volume
Reduction of TMV ImplemqiUbUity Total Cost'
SO
Reduces concentrations to Very easy.
acceptable levels through
natural attenuation.
Reduces concentrations to Very easy.
acceptable levels through
natural attenuation.
Significantly reduces Technically
implementable.
Significantly reduces Technically
implemenlable.
Significantly reduces
TMV.
Significantly reduces
TMV.
Technically
implementable.
Technically
implementable.
$668,000
$14.876,000
$23,917,000
$11,005,000
$10,757.000
-------
TABLE 23
SUMMARY OF REMEDIAL ALTERNATIVE COSTS FOR SITE OT-69 GROUNDWATER
Site Cost Criteria
Alternative G-l Alternative G-2 Alternative G-3 AlternativeG-4 Alternative G-5 Alternative G-6
OT-69 Capital Cost
O&M Cost
30-Year Present Worth Cost
SO $122.000
$0 $40.000
$0 $668.000
$13.090,000
$1,911.000
$14,876.000
$12,693.000
$1.598.000
$23.917.000
$5.211,000
$825,000
$11.005.000
$3,705,000
$1.004.000
$10,757.000
Source: (IT, I995a)
-------
TABLE 24
PRELIMINARY COST ESTIMATE FOR SITE OT-69 PREFERRED ALTERNATIVE
(G-2)
Item/Description
Quantity Unit
DIRECT CAPITAL COST (DCC)
Natural Attenuation Work Plan , iumpsum
Install 10 Dedicated Sampling Pumps i |umpsum
Allowance for Unidentified Equipment i lump sum
Allowance for Offloading and Setting Equipment 1 Jump sum
Freight Allowance
Subtotal Construe!
Contingency 20%ofCC
Subtotal Direct Capita
TOTAL CAPITAL REQj
PERIODIC OPERATING AND MAINTENANCE COST
Annual Groundwater Monitoring (10 wells, 4 quarters)
Annual Maintenance Cost
40 wells
1 lump sum
PRESENT WORTH
Discount Rate
Years
30-YEAR PRESENT WO1
Unit Coat ($)
$56,000
$31,000
$9,000
$2,000
$4,000
Son Cost (CC)Q
•1 Cost (DCC)Q
UIREMENT f"~
$1.000
7%
46
RTHCOST |
Total Cost ($)
$56,000
$31.000
$9.000
$2,000
$4,000
$102,000 1
$20,000
$122,000 |
$122.000 I
$39,000
$1.000
$668.000 1
Assumptions:
Estimated duration of remediation is 46 years.
Source: IT, 1995a
-------
TABLE 25
SUMMARY OF CURRENT REMEDIAL ALTERNATIVE COSTS FOR OU 3 SITES
WITH ACCELERATED ACTIONS PERFORMED
Site
FS Estimated Actual
Selected Present Construction
Alternative Worth Cost *b Cost to Date*
Current Estimated
Annual O&M
Cost*
Current Estimated
Present Worth
Cost**
Landfill Sites
DP-03
DP-04
LF-12
LF-14
LF-44
SEDA
TPH/VOC Sites
WP-17
FT-l9a
FT-19c
OT-51 (Soil)
4
4
3
3
2
3
9
9
8
9
$1,200,000
$1,100,000
$1,600,000
$3,800,000
$510,000
$7,800,000
$270,000
$780,000
$680,000
$660,000
$340,000
$340,000
$1,093,000
$1.639,000
$51,000
$3,795,000
$72,000
$191,000
$224,000
$96,000
$4,000
$4,000
$16,000
$24,000
$500
$53.000
$4,000
$6,000
$11,000
$6,000
$1,100,000
$900,000
$2,200,000
$3,100,000
$390,000
$6,600,000
$210,000
$450,000
$520,000
$380,000
a) Includes long-term groundwater monitoring for an assumed period of time.
b) FS present worth costs are initial estimates as presented in the OU 3 FS Report (Montgomery Watson, 1997a)
developed prior to implementation of accelerated actions.
c) Based on actual construction costs for accelerated actions performed to date.
d) Current estimated present worth is modified from FS present worth by including actual construction costs
and current estimated O&M costs.
-------
-------
Q.
5*
>
Appendix A
MONTGOMERY WATSON
-------
-------
APPENDIX A
ACTION ITEMS TO MEET ROD REQUIREMENTS
-------
-------
APPENDIX A
ACTION ITEMS TO MEET ROD REQUIREMENTS
Table 1 of this document lists the Operable Unit (OU) 3 Installation Restoration Program (IRP)
sites and presents the selected remedy for each site. As described in Section 2.9, accelerated
actions have been initiated at some of the OU 3 Sites presented in this OU 3 Record of Decision
(ROD). The following is a summary of the action items identified in this document to be
performed to satisfy the requirements of this ROD for the OU 3 IRP sites:
• Develop OU 3 Landfill Post-Closure Maintenance and Monitoring Plan.
• Develop Water Quality Protection Standards (WQPS) for OU 3 Landfill sites. The
WQPS will be developed within 6 months of the signing of this ROD and will be
based on the available groundwater data to establish baseline values for which
future sampling results will be compared.
• Develop detailed language describing access and land use descriptions.
• Prepare periodic Site WP-17 Bioventing operations and maintenance (O&M)
Reports.
• Prepare Site WP-17 Closeout Report.
• Prepare periodic Site FT-19a Bioventing O&M Reports.
• Prepare Site FT-19a Closeout Report.
• Prepare periodic Site FT-19c SVE O&M Reports.
• Prepare Site FT-19c Closeout Report.
• Complete closure of large diameter casing well near Site OT-51.
• Prepare periodic Site OT-51 Bioventing O&M Reports.
• Prepare Site OT-51 Closeout Report.
• Prepare Site OT-69 Closeout Report.
A-l
-------
-------
TJ
Q.
5°
Appendix B
MONTGOMERY WATSON
-------
-------
APPENDIX B
CRITERIA FOR ACTIVE SITE REMEDIATION - SITE OT-69
-------
-------
Memorandum
lto: D. Caron, GAFB Dote: November 6, 1995
From:
K. Brown, IT /Ct* IT Project No. 409887
SubjectCRTTERIA FOR ACTIVE SITE REMEDIATION - SITE OT-€9
The following text addresses concerns stated by the California Regional Water Quality Control
Board (RWQCB) in their October 16, 1995 correspondence.
Model Projections
Specific trichloroethene (TCE) concentration projections, over time, for monitoring wells located
in the MW-49 and Operable Unit 2 (OU2) areas have been developed. Figure 3-1 of the
TCE/PCE Remedial Investigation/Feasibility Study is attached and presents the impacted area
locations. Tables 1 and 2 illustrate the decreasing concentration of TCE which is expected
during natural attenuation. Predicted concentrations are stated as a range, showing 15 percent
variation about the mean. This 15 percent range is used to account for non-analytical variances
which may occur during sampling. Analytical method variances will also be considered (see
Criteria for Evaluating Data).
Non-analytical variances are attributable to normal variations recognized with changes in
sampling personnel, procedures, and equipment These variances should be accounted for,
especially during the sampling of a volatile.
A two-dimensional numerical model, Solute, was used to model the fate and transport of TCE.
For a detailed discussion refer to Section 4.0 of the TCE/PCE RI/FS. Conservative estimates
of modeling parameters such as hydraulic conductivity, dispersitivity, density, and porosity were
used during modeling. As a result, no variability was built into the model that would account
for analytical and non-analytical variances. All model data was generated using 1995 sampling
results.
Ground Water Monitoring
Five monitoring wells located in the MW-49 area will be monitored three times per year from
September 1995 through July 1996. These monitoring wells include MW-43, MW-41, MW-15,
MW-49 and MW-60, and were selected for monitoring by the George Air Force Base (GAFB)
remedial project managers (RPM). All wells will be sampled using a combination of slow purge
and bailing techniques and analyzed for TCE via U.S. Environmental Protection Agency (EPA)
Method 8010. The first round of groundwater sampling was completed on September 29, 1995.
Additional rounds have been contracted and are scheduled for February and July 1996.
44.6-as
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081011 **«e 2 November 7, 1995
Fbllowing July 1996, these wells will be monitored yearly by Method 8010. During the
evaluation of groundwater data the appropriateness of well selection will be evaluated.
TCE/PCB-impacted wells within OU2 include MW-28, MW-30, MW-46, MW-23, and MW-14.
MW-23 and MW-14 were identified as no further action sites due to low concentrations; the
remaining OU2 well locations will be monitored for TCE/PCE quarterly during the JP4 Natural
Attenuation Treatability Study.
MW-23, included in 1995 sampling rounds, provides an illustration of the natural attenuation
of chlorinated solvents in the presence of aromatic cometabolites (i.e., toluene). Specifically,
the MW-23 7 micrograms per liter Gig/L) 1992 TCE concentration has been reduced to 2.8 j*g/L
(1995) with corresponding detection of biological byproducts (dichloroethane [DCA]).
The remaining OU2 wells (MW-28, MW-30, and MW-46) were not sampled directly in 1995,
however, wells downgradient of these primary wells were sampled and analyzed by EPA Method
8010. In association with MW-28, downgradient wells MW-47, MW-33, and MW-31 were
sampled twice in 1995 and will be monitored quarterly during 1996. TCE concentrations in
MW-47, MW-33, and MW-31 were 1.1,0.98, and 2.7 ftg/L, respectively. Each well also had
DCA, a degradation byproduct.
MW-36 and MW-64, downgradient of MW-30 and MW-46, were sampled in 1995 and contained
approximately 3.1 and 1.4 pg/L TCE, respectively. DCA was detected in MW-64.
Overall, there is evidence supporting the cometabolic removal of TCE during OU2 plume natural
attenuation. Sampling and analysis of selected OU2 wells will occur quarterly during 19% and
yearly thereafter.
Criteria for Evaluating Data
All data will be evaluated following the completion of each sampling event. Once data has been
accepted as valid through review of the data quality objectives, results will be compared with
the previous sampling results and predicted concentrations to screen for significant deviations.
If there is a significant deviation in contaminant concentration, the well(s) will be resampled in
a timely manner.
As noted in Model Predictions, predicted concentrations are stated as concentration ranges (15
percent around the predicted concentration). If the sampling data indicates that the TCE
concentration is above the predicted range, the analytical variability of the sampling method must
be determined. If the measured concentration is 2 analytical standard deviations above the
predicted concentration range, verification measures will be initiated. Two standard deviations
are necessary to assure that the contaminant concentrations are truly above the anticipated range
given the extremely low contaminant concentrations that are being considered.
-------
Cuoa ***« 3 November 7, 1995
For example, if TCE concentrations at MW-41 are predicted to range ftom 1.50 to 2.02 pg/L
during the second year of groondwater sampling, however, the actual concentration is measured
at 2.5 pg/L, the following steps win be taken.
1. Determine*the variability of the analytical method employed at the time of analysis.
2. Consider the analytical standard deviation and calculate the possible contaminant
concentration range.
3. Determine if the calculated range in concentration is 2 standard deviations above the
predicted concentration range.
4. If the concentration is 2 standard deviations above the predicted concentration range,
initiate verification measures.
5. If the concentration is less than 2 standard deviations above the predicted concentration
range, maintain routine sampling schedule.
If at the end of this process it is determined that the analytical standard deviation is 0.3 pg/L
for the above example, men the possible contaminant range is calculated to range up to 2.62
Mg/L. The measured concentration at MW-41 fall* within this concentration range, therefore,
the results indicate that the routine sampling schedule should be maintained.
Throughout data evaluation, the Air Force wffl maintain open lines of communication with all
FFA signatories, including the Water Board.
Verification Measures
If it is decided through evaluation with the Water Board that significant concentration increases
are documented per the criteria presented above in any of the wells sampled during a single
event, the well will be resampled in a timely manner. Additionally, the predictive model will
be rerun (baseline will not be changed - the model only calibrated) and selected monitoring wells
reevaiuated to determine their appropriateness in light of potential plume movement. All data
and modeling results will be submitted to the GAFB RPM members for discussion prior to
revising any sampling protocol.
Once the verification measurements are completed, the Air Force and regulatory agencies will
meet again to review all data generated and decide on the requirement for an active remediation
or further monitoring and recalibration of the predictive model. If no treatment or increased
monitoring is required then aquifer monitoring will revert back to yearly.
Triggers for Active Remediation
During increased monitoring, if any of the wells tested indicate increased contaminant
concentrations (per the method developed in Criteria for Evaluating Data), the Air Force will:
1. Implementation of the active remedy, or
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Caron
Pftge 4
November 7, 1995
2. Acceptance of a proposal to continue monitoring at an increased frequency, rerun the model
and/or re-evaluate the monitoring wells used.
In the event that an active remediation system is required, in situ air stripping/soil vapor
extraction (SVE) recovery will be implemented. The selection of this alternative is valid for at
least 10 years based on the information available during the development of the RI/FS No
additional feasibility studies are anticipated prior to implementation. Revised cost estimates
should be prepared for the year in which the contingent remedy would be implemented.
The implementation of in situ air stripping with SVE recovery at the MW-49 area would not
negatively impact any vadose zone remediation since none is required. (No contaminant source
areas were identified in the vadose zone.) It should also be noted that this contingent remedy
applies only to the MW-49 area and may not be recommended for remediation of the OU2 area.
As future advances in engineering practice may occur, a reevaluation of remedial alternatives
is recommended prior to implementation or selection of an active remedial system beyond the
next decade. The requirement for additional feasibility studies should be determined during the
reevaluation process.
Active remediation of OU2 will not adversely impact the natural attenuation of the MW-49
plume. The OU2 plume is downgradiem of MW-49 and will encompass this TCE plume.
It should also be noted that the Air Force wfll maintain deed restriction/institutional controls on
tbeproperty. In addition, the Air Force will pursue through the County of San Bernardino the
identification of all Base wells within impacted areas as well exclusion zones as a secondary
backup to deed restrictions. In the event that deed restrictions fail and a well is drilled into the
plume, the Air Force will initiate well head treatment to remove any contaminant prior to water
usage.
The Air Force also suggests that the protocol presented in this document be reviewed every five
years along with the ROD by all regulatory parties of the FFA to provide an additional layer of
surveillance to the process.
Financial Assurances
The U.S. Air Force will make a timely request for funds by identifying to the Department of
the Air Force the funding needed to complete the ROD activities described in the most recently
approved final ROD in accordance with Executive Order 12088 and OMB circular A-106 which
is updated bi-monthly and for which funding requests are made at least two years in advance
(when possible) and which are incorporated herein by reference, or any pertinent amendments
to those requirements.
t
'
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Caron Page 5 November 7, 1995
In the event that Congress fails to appropriate necessary funding for ROD activities at George
Air Force Base, the following will occur
a. The Air Force will so advise all FFA signatories within 90 days of such failure: and
b. The Air Force will provide to all FFA signatories documentation of all measures it will
undertake to ensure that ROD activities are completed in accordance with the most
recently approved ROD. These measures may include, but are not limited to, continuing
to seek funding for implementing the contingent remedy.
cc: J. Cass, Water Board
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8
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(V
Table 2
Predicted TCE Concent rations Selected OU2 Sites
George Air Force Base, California
IT Project No. 409887
Yetr
U«
I
2
3
4
S
10
15
20
25
30
35
40
45
50
MW-29
7.10
(I»S)
1.21
-
MW-29
Rufe
6.04-1.17
1.03 - 1.39
MW-M
10.00
(1993)
4.54
MW-34
luge
1.50-11.5
3.16-5.22
MW-2J
14.00
(1993)
1.74
7.54
7.27
7.03
6.14
4.64
MW-2S
lute
11.90-16.10
7.43 - 10.05
6.41 - 1.67
6.11-1.36
5.91 -l.0t
5.22-7.06
3.94- 5 J4
MW-4*
16.00
(1993)
5.77
5.10
5.56 .
5J3 •
J.34
4.66
•
M1M6
RwfC •
13.60-11.40
4.90-6.64
4.93 - 6.67
4.73-6.39
4.53-6.13
4.54-6.14
3.96- 5 36
Hate:
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!_Jls
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I
I
Appendix C
MONTGOMERY WATSON
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APPENDIX C
ADMINISTRATIVE RECORD
(On file at the GAFB Environmental Programs Office
Contact: Air Force Base Conversion Agency
Department of the Air Force
AFBCA/DD, Building 321
13436 Sabre Boulevard
Victorville, California 92394)
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Appendix D
I
§
Q.
5"
o
MONTGOMERY WATSON
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APPENDIX D
RESPONSES TO AGENCY COMMENTS TO APRIL 1997 DRAFT ROD
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RESPONSES TO USEPA COMMENTS DATED JULY 3,1997 ON THE
DRAFT RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
Comment No. 3:
Response:
Comment No. 4:
Response:
As previously agreed at RPM meetings and confirmed in the OU 3
FS, GAFB would not justify selected remedies based on exceeding
human health risk. Accordingly, delete or modify any reference to
the same within the document.
As discussed at the August 14, 1997 RPM meeting, the justification
for the selection of remedies is based on the nine CERCLA criteria,
which includes protection of human health and the environment.
Historically, the RPMs have requested that risk management decisions
be considered for sites where the risk exceeded l.OE-6. Text has been
added to Section 2.9 (Current Site Status) to state that "in an effort to
accelerate the remedial process, to minimize present and future
environmental risks, reduce potential impacts to groundwater, and
facilitate timely transfer of property to the community, cleanup
activities have been initiated under the direction of the USAF, at some
of the sites presented in this ROD" to clarify that site risk is not the
only reason the RPMs agreed to implement remedial actions.
An additional summary statement for Section 2 should cite that
ecological risk concerns will be managed through a monitoring
plan.
A discussion of the ecological monitoring plan has been added to
Section 2.9.
For clarity and consistency, Figure 6 should also show the location
of LF-35 it was categorized as a site requiring some action.
Site LF-3S has been added to Figure 6.
A brief summary should be made, for the results of GAFB's follow
through with U.S. Fish and Wildlife (Doug Laye), for desert
tortoise concerns related to the skeet ranges.
The subject of this ROD is the OU 3 IRP sites. The skeet ranges are
not IRP sites.
D.l-1
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RESPONSES TO USEPA JULY 3,1997 COMMENTS (Continued)
Comment No. 5:
Response:
Comment No. 6:
Response:
Comment No. 7:
Response:
OT-69 should be cited that it has been transferred to OU 2. A
very brief explanation should outline why it was transferred.
Site OT-69 is currently an OU 3 site. A sentence has been added to
Section 1.0 clarifying that the TCE in the vicinity of FT-20 is now part
ofOU2.
Landfill sites (left in place) should show the planned deed
restrictions and/or land use.
The text has been modified where appropriate to provide additional
detail regarding deed and land use restrictions. See responses to the
DTSC's (Ron Okuda's) comments. Actual restrictions will not be
written until how the land transfer will occur is known.
The pesticide dieldrin agreements for continuous monitoring
requirement, additional investigation (if needed), and related
contingent remedy discussed at the June 30, 1997 meeting should
be cited in the ROD.
As agreed during the RPM Meeting on September 17, 1997, the
dieldrin that has been detected in wells in the eastern portion of the
base (in the vicinity of LF-39) are not currently considered part of OU
3; therefore, it is not presented in this ROD. Text has been added to
Section 2.1.1 (Description of Operable Units) to state that the dieldrin
detected in wells in the eastern portion of the base will be addressed as
part of another OU.
D.l-2
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RESPONSES TO DEPARTMENT OF TOXIC SUBSTANCES CONTROL COMMENTS
DATED JUNE 27,1997 ON THE
DRAFT RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
RON QKUDA'S COMMENTS
Comment No. 1: Section 2.5.2.2, Alternative 2: Institutional Controls Pages 2-24
and 2-25. This section in part states:
"Alternative 2 includes access and land use restrictions, surface
restoration, groundwater monitoring, and the 5-year site review.
Access restrictions will involve the installation of 8-foot-high
chain-link fences with barbed wire and/or posting of warning signs
posted along the perimeter of the site. The locations of the fences
at each landfill would be determined as part of the design.
The implementation of land use restrictions at the OU 3 landfill
sites will depend highly on the disposal and reuse plans for the
GAFB property. There should be agreement between the USAF.
future owners of the property, and the concerned regulatory
acencles regarding the types of land use that may be restricted on
site-bv-site. parcel-bv-parcel basis.
Surface restoration will involve..."
The land use restrictions are a part of the remedy and are
necessary to assure the protectiveness of the remedy. The future
owners of the property should not have the ability to negotiate the
restrictions. The human health risk assessment was conducted to
determine the risks associated with a future commercial/industrial
use scenario. To protect human health, land use restrictions
should be recorded prohibiting residential uses.
I recommend that the above underlined sentences be revised as
follows:
"The implementation of land use restrictions at the OU 3 landfill
sites will assure the protectiveness of the remedy and human health.
Deed restrictions will be recorded to restrict use of the sites for the
following purposes: (a) A residence, including any mobile home or
factory built housing, constructed or installed for use as permanently
D.2-1
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RESPONSES TO DTSC JUNE 27, 1997 COMMENTS (Continued)
occupied residential human habitation, (b)A long-term care hospital
for humans, (c) A traditional public or private school for persons
under 21 years of age, (d) A day care center. In addition, the deed
andfe^g." diStUrbanCe °f the *""&« fOV"> ^surface soils
If the landfill is located over the contamination plume, the ROD
againsl Pu™Pin^nJection of
If the BCT is aware of other restrictions that would be necessary
to assure the protectiveness to human health and the environment,
those restrictions should also be discussed/disclosed in ROD.
There is a possibility that the remedy is not compatible with the
future reuse plan. If this is so, and the BCT does not (or cannot)
change the remedy to accommodate the reuse plan, the ROD
should provide a clear description of the constraints (land use
restrictions) that the Local Redevelopment Authority will have to
comply with in the future.
A^'^**1"!11*8" that *' Air Foree- *« Local Redevelopment
Authority and the regulatory agencies can negotiate would be a
protocol the future landowner or the Air Force will follow to seek
™ "^ m ** restrictions> or h«ve the restrictions removed.
The deed can have a section specifying that the future landowner
can petition the UA EPA or other regulatory agencies based on
revised/new data (he., data has demonstrated that bioremediation
has reduced the concentration of the COPCs to a level that would
allow residential development).
Response: The text has been modified as requested with minor revision for
consistency and clarity.
Comment No. 2: Section 2.6.2, Description of TPH/VOC Site Alternatives, Pag,* 2-
^^ onn 9_C^4
53 and
The description of the land use restrictions in this section is
inadequate. The discussion of Alternatives 8 (Soil Vapor
Extraction) and Alternative 9 (Bioventing) state that "land use and
access restrictions will be employed until remediation is confirmed
to be complete"; however, the specifics of the restrictions are not
discussed. Will the areas be fenced in a manner similar to the
D.2-2
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Response:
RESPONSES TO DTSC JUNE 27,1997 COMMENTS (Continued)
landfills? Will restrictions be imposed to prevent disturbance of
the remedy and groundwater monitoring wells? Will the future
landowner be prohibited from disturbing the soil? This section
needs further discussion of the restrictions.
Alternative 11 (Oxygen Enhancement with ORC) does mention
land use restrictions to prohibit use for domestic purposes. In
addition, I would recommend that the ROD include something
about the restrictions to prohibit disturbance of the remedy and
monitoring wells.
Sections 2.6.2 and appropriate subsections have been modified to
address these issues as follows:
• A separate paragraph has been added to Section 2.6.2.3 to
specify the nature of land use and access restrictions for
Alternative 8.
• A statement has been added to Section 2.6.2.4 that the land
use and access restrictions for Alternative 9 would be the same
as Alternative 8.
• The change requested for Alternative 11 (Section 2.6.2.6) has
been made.
Comment No. 3:
Response:
There are numerous sites in the Draft OU 3 ROD that are
proposed for NFA where the health risks were evaluated for a
commercial/industrial, exposure scenario. If the sites are not
protective enough for unrestricted uses (i.e., residential), land use
restrictions should be imposed at those sites. This would mean
that those sites are no longer eligible for a NFA decision.
The OU 3 RI Report details the approved methodology used for the
risk assessments performed for OU 3 sites. Table ES-4 of the final OU
3 RI Report (Montgomery Watson, 1996a) presents the complete
summary of the results of the human health risk assessment analysis.
Potential risk assessment exposure scenarios included:
industrial/commercial, trespasser/visitor, construction worker
(potential surface soil exposure), construction worker (potential
subsurface soil exposure), and future resident. The exposure scenarios
evaluated for a particular site were dependent on the expected
exposure pathway and the proposed land use as presented in the
Management Action Plan (MAP) (USAF, 1993). In most cases,
multiple scenarios were evaluated for a particular site including the
future resident scenario if the site was in a parcel with the potential for
residential use.
D.2-3
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RESPONSES TO DTSC JUNE 27,1997 COMMENTS (Continued)
To clarify this issue in the OU 3 ROD, the text that summarizes the
risk assessment for each site requiring action has been revised to
clearly present all risk assessment scenarios that were evaluated for
that site and reference the MAP and OU 3 RI Report where
aDDronriafe
appropriate
D.2-4
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RESPONSES TO DEPARTMENT OF TOXIC SUBSTANCES CONTROL COMMENTS
DATED JULY 9,1997 ON THE
DRAFT RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
During the Remedial Project Managers (RPM) meeting in
Walnut Creek where the remaining risk assessment issues were
discussed, it was agreed that the Air Force would include in the
Record of Decision, the basis for expediting the accelerated
actions was NOT risk based, rather it was for reuse
considerations. The ROD must be absolutely clear on this issue
and it need only state the agreements developed hi this process.
The meeting referred to above was held to discuss human health risk
assessment on October 1, 1996. This issue was discussed; however,
in that context, it was also stated by the Air Force that the decisions
to support the final remedy were based on the nine CERCLA criteria
which includes overall protection of human health and the
environment (i.e.f risks). The outcome of that meeting was presented
in minutes submitted to the RPMs October 7, 1996. Subsequent to
the October 1, 1996 meeting, the RI was approved as final and the
FS was revised (via inserts) and approved as final. The presentation
of the decisions in the OU 3 ROD are consistent with the
presentation in the final OU 3 FS.
In addition to the October 1, 1996 meeting, a ecological risk meeting
was held on September 19, 1996. Please note that ecological risks
are also considered in the determination of the most appropriate
remedy.
This issue was again discussed during the August 14, 1997 RPM
meeting regarding the preparation of the OU 3 Proposed Plan. At
that time, it was agreed that risk management factors were
considered in the decision whether to carry a site through the FS
process or to propose no further action.
The deed restrictions, land use limitations and access restrictions
must be further delineated. Mr. Ronald Okuda, Environmental
Assessment and Reuse Specialist has provided comments to
bring the document up to par. Said comments are attached.
See responses to Ronald Okuda's comments.
D.3-1
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 3:
Response:
Comment No. 4:
Response:
Comment No. 5:
Response:
This ROD must provide contingencies for the ongoing field
efforts in the event that the proposed remedies fail to perform as
expected. For example, if it is found, through verification
sampling that the Bioventing activities simply pushed the
contaminants away from their original locations, it will be
necessary to chase the contaminants, define their extent and
implement an agreed to remedy. We hope this will not be
necessary but it is necessary to consider the possibilities.
Text has been added to appropriate places in the document to clarify
that the effectiveness of the remedies are being assessed as part of
the ongoing O&M and long-term monitoring. Assessment of system
effectiveness will be the focus of the 5-year site review.
This ROD mentions OT-69 will be addressed as part of OU 2.
The situation has changed and as of May 6, 1997 during the
RPM meeting it was decided to include OT-69 groundwater
plumes with OU 3. Please revise the text, figures and tables as
necessary.
OT-69 has been added to the text as an OU 3 site.
The ecological risk management agreements which were agreed
to are missing and should be included in the ROD.
The primary agreement for ecological risk management was the
presentation of an ecological monitoring plan. This plan is now
summarized in Section 2.9. hi addition, this section documents the
actions that have occurred to date, including the hot spot removal
that was performed prior to construction of the soil cover at Site DP-
04 to reduce potential risk to burrowing animals.
SPECIFIC COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Pg. 1-1, Para. 3. Site OT-69 groundwater is described as having
been relegated to OU 2 to be addressed. This is no longer
accurate. It will stay with OU 3 and must be addressed in the
ROD See General Comment No, 4.
See response to General Comment 4.
Pg. 1-2, Para. 3. The last part of the first sentence, "and are cost
effective." should be deleted. The Air Force could have saved
D.3-2
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Response:
Comment No. 3:
Response:
Comment No. 4:
Response:
Comment No. 5:
Response:
considerable amounts of time and money had they pursed
additional Remedial Investigations as requested by regulators.
By expediting the accelerated actions in lieu of sampling, the Air
Force may have committed themselves to post closure activities
such as long term monitoring at the landfill sites. Which are
rather costly. This part of the sentence must be deleted.
All accelerated actions were performed with the consent and
participation of the regulatory agencies through the RPM meetings,
document reviews, remedial action work plans, etc. In addition, all
sampling met or exceeded that presented in the final OU 3 Work
Plan Addendum (JMM, 1992). The sites that were carried into the
FS process were agreed upon in the final OU 3 FS Report. In the FS,
cost analysis was performed to satisfy that aspect of the nine
CERCLA criteria and was considered in alternative selection.
Therefore, in that context, the most cost effective option for the site
that required action was selected.
Pg. 1-3, Para. 3. Please replace the name and title of the DTSC
person who will sign this document. The proper name and title
is:
John E. Scandura, Chief
Southern California Operations
Office of Military Facilities
Department of Toxic Substances Control
The text has been modified accordingly.
Pg. 2-1, Para 2. The last sentence implies that Figure 6 has all
the sites associated with all three Operable Units. This must be
revised. In addition, it seems that the sites included on Figure 6
are only those sites which are action recommended. Please
include sites LF-35 and OT-69 (groundwater) as well as any sites
which have actions recommended.
The text now refers to Figure 2 which presents all three Operable
Units. Sites LF-35 and OT-69 have been added to Figure 6.
Pg. 2-2, Para 1. See previous comments on site OT-69
groundwater. Revise the last sentence accordingly.
The text has been modified accordingly.
the text as an OU 3 site.
OT-69 has been added to
D.3-3
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 6:
Response:
Comment No. 7:
Response:
Comment No. 8:
Response:
Comment No. 9:
Response:
Pg. 2-7, Para 2. The last sentence which discusses OU 1
discharge of effluent into the arroyo is no longer accurate.
Please re-iterate the existing conditions for OU 1 discharge as of
the June 4, 1997 RPM meeting and the July 1, 1997 RPM
meeting. The final OU 1 discharge will be in agreement with the
ROD or the Team will have to go thru a ROD modification
procedure.
The text has been revised to state that the arroyo intermittently
receives discharge from the OU 1 extraction and treatment system.
Pg. 2-9, Para 2. The DTSC recommends that the last sentence in
paragraph 2 and paragraph 3 be deleted. The statements are
speculative and can either be investigated or left out of the ROD.
The first sentence in question has been deleted. The second sentence
has been revised.
Pg. 2-11, Para 3. Please modify the last sentence as follows:
replace "these investigations to" with "those investigations in an
effort to-.*' Basically the Air Force refused to do additional
characterization. The regulators did not force the issue since the
work which was performed satisfied the minimum requirements.
Never the less, the proposed revisions is more appropriate and
must be included hi this ROD.
The sentence is introductory and refers to basewide activities. To
clarify, the text has been revised to state "the USAF has performed
investigations in an effort to..." All OU 3 sampling met or exceeded
that in the final OU 3 Work Plan Addendum (JMM, 1992).
Pg. 2-13, Para. 6. The tense for this paragraph is incorrect, it
will take place but has not taken place. In addition the dates
have subsequently changed and must be updated. Currently the
public meeting is scheduled for August 14,1997 and the 30 day
public comment period should start around July/August time
frame. This section must be updated.
This version of the ROD is being submitted after the public meeting
and public comment period have occurred. The text has been revised
to state that the public meeting was held on October 8, 1997 and the
public comment period ended on October 22, 1997. Past tense is
now appropriate.
D.3-4
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 10:
Response:
Comment No. 11:
Response:
Comment No. 12:
Response:
Comment No. 13:
Pg. 2-14, Para. 3. See prior comments regarding site OT-69.
This site will not be addressed in the OU 2 ROD as stated in the
document This must be updated.
See responses to prior comments regarding site OT-69.
Pg. 2-14, Para. 5. The use of land use restrictions for LF-35 in
and of itself is insufficient. Deed restrictions, land use
restrictions and access restrictions must be specified for all sites
which have potential hazardous wastes and substances left in
place. See Ronald Okuda's comments.
The text has been modified to be more clear.
Ronald Okuda's comments.
See responses to
Pg. 2-16, Para. 1. The last sentence, in its present form is
misleading. Actually, die modeling, shows that there is no
potential for contaminant leaching in to the groundwater. The
model has certain assumptions which may or may not correlate
to the actual amount of contamination present In practical
terms, the post closure landfill requirements for monitoring
apply at these landfills due to the high uncertainties associated
with the data. This is due to the low quantity of analytical data
available. In addition the remedy is to leave wastes in place
which requires deed restrictions, access limitations and land use
restrictions in perpetuity. This sentence and all such sentences
may be deleted or replaced with language which incorporates the
above comments.
The sentence referenced (and other similar sentences in the
document) have been modified to state that "modeling results
indicate that there is no potential for contaminant leaching to
groundwater."
Pg. 2-16, Para. 3. The first and second sentences contradict each
other. Is there an ecological risk issue or not The DTSC
position is that there is since the desert tortoise can easily
burrow below the 12 to 18 inches of cover placed on the landfills.
The Air Force agreed to implement risk management measures
to limit the access and future use of all the landfills. See the Risk
Assessment meeting in Walnut Creek in December 1996. This
agreement was reached in lieu of additional Remedial
D.3-5
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Investigations which may have been performed. The agreements
from the meeting must be included in the ROD.
Response: The text has been revised to clarify the distinction between the
qualitative ecological benchmark screening and the subsequent
quantitative bioaccumulative food chain modeling.
At a meeting at the USEPA offices in San Francisco, California on
December 11, 1995, it was agreed that food chain modeling for
bioaccumulative compounds would be performed to address any
perceived insufficiency of data. The text now reads that the
localized presence of PAHs (not included in the bioaccumulative
food chain modeling) may be a potential risk to ecological receptors.
However, the food chain modeling performed for bioaccumulative
compounds at DP-03 did not suggest a risk to vegetation or wildlife.
This information is discussed in detail in the final OU 3 RI Report
(see Table ES-5 for a summary). In addition, these results were
presented at the ecological risk assessment meeting in Walnut Creek
on September 19, 1996. It is assumed that this is the meeting which
is referenced above.
A discussion of the ecological monitoring plan is now presented in
Section 2.9 of the OU 3 ROD.
Comment No. 14:
Response:
Comment No. 15:
Response:
Pg. 2-17, Para. 1. The last sentence needs a little clarification,
add "within 100 years." or delete the phrase "... no potential"
Once again due to the low confidence in the data sets used or
high uncertainties, ALL these comments must be revised or
deleted.
To clarify, this statement, and other similar statements for other sites.
have been revised to read "within 100 years." All prior comments to
the OU 3 RWS related to perceived concerns regarding the agency's
low confidence in data sets and uncertainties were addressed in the
final OU 3 RI/FS Reports. The text referenced is primarily a
summary of discussions presented in the OU 3 RI and/or FS (for
example, the specific text referenced is presented on page 3-7 of the
final OU 3 FS [Montgomery Watson, 1997aJ).
Pg. 2-18, Para. 1. Comment 2-17,1 applies at the end of the first
paragraph.
See response to Specific Comment 14. See also page 3-3 of the final
OU 3 FS (Montgomery Watson, 1997a).
D.3-6
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 16:
Response:
Comment No. 17:
Response:
Comment No. 18:
Response:
Comment No. 19:
Pg. 2-18, Para. 2. Why was the highest estimated excess cancer
risk estimated for the future risk scenario at this landfill?
Landfills which are not clean closed should be evaluated for
industrial/commercial scenarios like the other landfills.
To clarify this issue, the text that summarizes the risk assessment for
each site requiring action has been revised to clearly present all risk
assessment scenarios that were evaluated for that site.
For example, this site (LF-12) was evaluated for five scenarios (i.e.,
industrial/commercial, trespasser/visitor, etc.). The exposure
scenarios evaluated for a particular site were dependent on the
expected exposure pathway and the proposed land use as presented
in the Management Action Plan (MAP) (USAF, 1993). The text
referenced above is presenting the highest risk observed because it is
the risk that would drive risk management decisions. The final OU 3
RI (Montgomery Watson, 1996a) presents the complete results of
this analysis and discusses the approved methodology.
Pg. 2-18, Para. 4. The paragraph implies that the remedies were
selected based on risk. This is not the case and the paragraph
must be re-written or deleted. See general comment No. 1. This
section must be revised accordingly.
See response to General Comment 1. Risk was part of, but not the
only, determining factor for carrying a site through the FS process
(as stated in the text) for many sites. Through the FS process, risk
management decisions were a consideration for the most appropriate
remedy as part of the nine CERCLA criteria.
Pg. 2-19, Para. 2. Comment 2-17,1 also applies here.
See response to Specific Comment 14. See also page 3-4 of the final
OU 3 FS (Montgomery Watson, 1997a).
Pg. 2-19, Para. 3. Why does the Air Force evaluate risk for
industrial/commercial in LF-14 and for the future resident
scenario in LF-12? Landfills are landfills and should be
evaluated to one standard, commercial/industrial, based on
current EPA guidance which addresses evaluation for future use
under the current use scenario. The risk numbers must be
comparable, i.e., address the landfills In this ROD under the
industrial/commercial scenario for human health.
D.3-7
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Response:
Comment No. 20:
Response:
Comment No. 21:
Response:
Comment No. 22:
Response:
Comment No. 23:
Response:
See response to Specific Comment 16.
Pg. 2-20, Para. 2. This paragraph is in need of being re-written.
The Base Closure Team (BCT) agreed not to stop work on the
accelerated actions with the condition that the work would not
be justified under CERCLA by risk assessment methodologies.
The Air Force agreed. This paragraph, and other similar
paragraphs, can quantify the human risk for
commercial/industrial scenarios with its associated confidence
levels. However, the basis for proceeding with the work was the
Air Force's prerogative to expedite reuse. The DTSC wouJd like
to see these points stipulated clearly in the ROD.
See responses to General Comment 1 and Specific Comment 17
*0 P3gC 3"5 °f ** final °U 3 FS
-------
RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 24:
Response:
Comment No. 25:
Response:
Comment No. 26:
Response:
Comment No. 27:
Response:
Pg. 2-24, Para. 7. As regards to access restriction, see previous
comments and Ronald Okuda's comments. The last sentence
has an inappropriate tense, the location of the fences do not have
to be determined, they are in place. Do not be afraid to state the
facts, whatever they are.
See responses to Ronald Okuda's comments.
The tense is appropriate as written. This section (2.5.2) presents the
alternatives that were evaluated for all landfill sites, not necessarily
the actions that have occurred (i.e., it is pah of the summary of the
FS process and discusses what would be done if a particular
alternative were selected for a particular site). Section 2.9 has been
added to the ROD that details the actions that have occurred to date.
Pg. 2-24, Para. 8. See Ronald Okuda's comments. Specify who
the concerned regulatory agencies are which will determine the
types of land use that may be restricted on the next page.
See responses to Ronald Okuda's comments.
Pg. 2-27, Para. 5,6. The DTSC would prefer to see the term
"reduced" in place of "practically eliminate" for these two
paragraphs. Rodents will burrow into the cover, as well as the
desert tortoise if the fences are not maintained. There needs to
be details included in the ROD which addresses the need for
ecological monitoring, post closure land fill cover requirements
and access control in the future.
The text has been modified accordingly.
Pg. 2-30, Para. 6. Risks have been effectively reduced to zero?
This is stretching risk assessment too far. Risk reduction has
been accomplished to some degree and this amount of risk
reduction can be quantified. The quantified level of risk
reduction can replace "zero."
The statement regarding reduction of risks to zero has been revised
to clarify that potential risk is minimized. At a risk assessment
meeting between the RPMs on September 19, 1996 the issue of
recalculation of risk was a point of some discussion (see meeting
minutes). Subsequent to that time, all agency comments to the OU 3
RI and FS report were addressed and it was accepted that a post-
D.3-9
-------
RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Comment No. 28:
Response:
Comment No. 29:
Response:
Comment No. 30:
Response:
Comment No. 31:
Response:
Comment No. 32:
Response:
Comment No. 33:
T rfsk assessmen' wou'd not be prepared for
the sites. Therefore, quantitative risk numbers arc not available.
lt k P°SSible that "* state
Air ForCC done
quantlfy *« **»• There is a
that the Air Force wouid have done the accelerated
actions in spite of the low levels of risk for reuse
However the DTSC must consider and where appropria
accept the no action alternative. Alternatives 1 a£d 2
therefore be revised accordingly.
As discussed at the August 14, RPM meeting, the agencies did not
histoncally accept no action (Alternatives 1) for the
rwSen £hTtiVCn2 W "** ^^ f°r Site
as written is histoncally accurate.
Pg. 2-36, Para. 4. Please delete line 3. Alternative 4 is less
expensive but NOT equally effective in satisfying the RAO's.
Alternative 5 differs from Alternative 4 in that is has the addition of
a synthetic Imer. The purpose of the liner is to further protect a^nsf
sC r±T I^UOn' .AIthOUgh at first «lance AltoLlve /may
ST TnTlSririfr A/terna!ive 4' the dat^ does not support
Sal 35 ^ T? eV^Uati°n PCrf°nned aBd Prcsented ^
5Sfi^.i •! ^ that ^ synthetic ]iner W°"W not
significantly aid in meeting this RAO.
Pg. 2-37, Para. 2. Why is the resident scenario used for LF-12?
See previous comments on this issue.
See response to Specific Comment 16.
Pg. 2-38, Para. 5. Same comment as 2-37, 2 for the SEDA.
See response to Specific Comment 16.
Pg. 2-41, 3rd bullet Delete this bullet
See response to Specific Comment 2.
levek n
and the evaluation criteria to which it was compared. The term
"Mgnificantly lower than the evaluation" is nebulous
D.3-10
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Response:
Comment No. 34:
Response:
Comment No. 35:
Response:
Comment No. 36:
Response:
Comment No. 37:
The text has been revised to summarize the evaluation criteria in
Section 2.6.1. The term "significantly" has been removed from the
sentence in question. The text in this paragraph has been revised to
clarify the point that the evaluation criteria were exceeded in one of
11 borings.
Pg. 2-48, Para. 3. The DTSC does not consider the Air Force
contractors, M&E, the correct entity to conclude that no further
action was warranted. Normally, the potentially responsible
party proposes recommendations, such as no further action and
the base closure team can concur unless we disagree amongst the
BCT. In such cases the US E.P.A. concludes on the CERCLA
issues and the Regional Board or DTSC concludes on state
issues.
The text in this sentence, and any similar sentences, have been
revised to give the more appropriate explanation that the conclusions
were drawn, reported, and agreed to by the RPMs.
Pg. 2-50, Para. 4. Figure 10 has a typographical error which
shows the cleanup goal for soils 20 feet above the groundwater at
125ug/kg. This must be corrected.
The figure has been modified accordingly.
Pg. 2-52, Para. 6. Which additional monitoring wells are
necessary to satisfy which specific monitoring components?
The monitoring wells referred to are hypothetical and therefore do
not have names. The text is summarizing the FS process (alternative
development) and is stating that additional monitoring well
installation might be required. For example, if an alternative with a
groundwater monitoring component was selected for a site were
sufficient downgradient monitoring wells were not available.
Pg. 2-53, Para. 7. Bioventing is an acceptable cleanup method.
However, it has been proven by confirmation sampling events
that this process simply moves certain contaminants from area X
to areas around X. We hope this is not the case here but a
contingency should be included where the Air Force commits to
remedying such a possibility.
D.3-11
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
Response:
Comment No. 38:
Response:
Comment No. 39:
Response:
Comment No. 40:
Response:
Comment No. 41:
Response:
Comment No. 42:
Response:
Text has been added to appropriate places in the document to clarify
that the effectiveness of the remedies are being assessed as part of
the ongoing O&M and long-term monitoring. Assessment of system
effectiveness will be the focus of the 5-year site review.
Confirmation sampling (soil or vapor) will be collected to confirm
the remedies have been completed prior to site closure.
Pg. 2-(55-61). The use of alternative 6,7,8 and 9 for soil and
alternatives 10 and 11 for groundwater makes it difficult to
compare, why not, rather, use the name of the process? This
will make it much clearer and easier to read.
Each alternative is defined at first use. In addition, a table is
presented cross referencing the number and name of each alternative
with the CERCLA criteria as follows: Table 3 for landfill sites,
Table 14 for TPH/VOC sites, and Table 22 for Site OT-69.
Pg. 2-(62-67). The DTSCs general comment No. 1 applies
throughout this section. The risk must be de-emphasized
throughout the ROD as agreed to by the BCT.
See response to General Comment 1.
Pg. 2-69, Para. 2. There are very few technologies which can
completely remove and treat contaminated soils. Lets replace
completely with adequately.
The text has been modified to state that the remedies "will remove
and treat contaminants in soils to below acceptable levels."
Pg. 2-69, Para. 5. In line 4 lets replace the term remedial with
accelerated actions since the work did not take place via an
approved ROD.
The text has been modified accordingly.
Pg. 3-1, Para. 2. The date has slipped form July 15, 1997 to a
proposed date of August 14, 1997 for the public meeting. Lets
keep the tense correct on these documents as they are being
revised.
See response to Specific Comment 9.
D.3-12
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RESPONSES TO DTSC JULY 9,1997 COMMENTS (Continued)
TableS T"6 Air F°rce should use the actual dollar amounts spent for the
actions taken thus far where the information is available. The
tables must be updated.
Response: Table 25 presents a summary of current present work cost estimates
as well as actual remedial action costs for the accelerated actions
performed for OU 3 sites. The text has been modified to clarify this
point.
D.3-13
-------
-------
RESPONSES TO LAHONTAN REGIONAL WATER QUALITY CONTROL BOARD
COMMENTS DATED JULY 11,1997 ON THE
DRAFT RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL
Comment No. 1:
Response:
Comment No. 2:
Response:
Comment No. 3:
Response:
Comment No. 4:
Board staff comments on the draft Proposed Plan are dated May
5,1997. Enclosed with Board staff comments was Regional Board
Resolution 6-97-62 authorizing the Executive Officer to sign the
OU 3 ROD provided there are not significant changes and that the
following comments are satisfactorily addressed.
Comment noted.
The ROD must indicate that the Regional Board has agreed to the
natural attenuation alternative for the Site OT-69 chlorinated
solvent plumes provided an active contingent remedy is specified
in the ROD and will be implemented. This contingency will be
implemented if the Regional Board deems that the natural
attenuation remedy is not restoring water quality objectives in a
timely manner.
Text presenting this information has been added to Sections 2738
and 2.9.2.
The cover letter to the draft ROD indicates that Site OT-69 has
not been included in the document because the remedial project
managers (RPMs) were still discussing whether to include the site
or not in the OU 3 ROD. The RPMs met on Tuesday, May 6 1997
and decided that the Site OT-69 plumes investigated by IT Corp
will be part of the OU 3 ROD.
The five plumes investigated by IT as Site OT-69 have been included
in the OU 3 ROD.
The RPMs also decided to consider the trichloroethylene
-------
RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
Response:
Comment No. 5:
Response:
Comment No. 6:
Response:
Comment No. 7:
Board staff request (May S, 1997) for a time schedule for
conducting additional investigations at this site.
The text has been revised to clarify that Site FT-20 (soil) is an OU 3
site for which No Further Action is recommended, and that "final
decisions regarding potential actions at the Site FT-20 (groundwater)
will be determined in the OU 2 ROD."
Closure activities at the landfill sites is now complete as indicated
in the draft ROD and long-term post closure maintenance shall
continue. Active soil remediation is in progress at Sites OT-51,
WP-17 and FT-19 as indicated in the draft ROD. The ROD
should reflect actual site closure and remediation costs as provided
by Montgomery Watson by letter dated April 22, 1997. During
the May 6, 1997 RPM meeting, Montgomery Watson indicated
that the table attached to the April 22,1997 letter did not include
monitoring costs. The long term costs should include collection of
groundwater monitoring data for an assumed period of time. The
cost estimate tables should include all costs (to date and projected)
and state assumptions.
The table referred to was included in the Draft OU 3 ROD as Table 22.
During the May 6, 1997 RPM meeting. Montgomery Watson stated
that the table column entitled "Current Estimated Annual O&M Cost"
did not include monitoring. However, it was also stated that
monitoring costs are included in the present worth cost (i.e., the total
costs include monitoring as written). This table (now Table 25) has
been revised to clarify that is presents the current estimates for sites
where accelerated actions have occurred to date using actual
construction costs. In addition, assumptions have been modified for
clarification.
Table 13 shows Quality Goals for TPH/VOC Groundwater Site
(OT-51). Changes should be made to this table. Comments 7-10,
below, pertain to this table.
See response to comments 7 through 10.
The numerical standard for odor (adopted secondary MCL) is 3
odor units and must be added to the table. Please see Table 64449-
A, Title 22, Cal. Code of Regulations. References should be made
to agreements made at the June 30, 1997 Applicable or Relevant
and Appropriate Requirements negotiations, meeting with
attorneys present, regarding the applicability of this criteria. In
D.4-2
-------
Response:
Comment No. 8:
Response:
Comment No. 9:
Response:
Comment No. 10:
RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
other words, the State and Air Force would disagree regarding the
applicability of the 3 odor unit secondary drinking water
standard, however the Air Force will clean up to that standard.
The header of the column titled 'Taste and Odor Threshold" in the
Draft ROD has been revised to "Suggested Concentration to Meet
Secondary MCL of 3 Odor Units."
The "agree to disagree" language established for OU 2 during the June
30, 1997 specifically regarding the 3 odor units has been added where
appropriate to Table 15 (ARARs for TPH/VOC sites).
A footnote should be added to the table clarifying that the
proposed federal secondary maximum contaminant levels are
constituent specific and may be used to represent the 3 odor units
for petroleum hydrocarbons, however when used independently,
they may not accurately reflect odor of a complex mixture. The
proposed federal secondary standards are not promulgated,
however the 3 odor unit secondary standard is promulgated.
See response to Comment 13. The requested language has been added
to Table 15.
Napthalene must be added to the table. A value of 20 ug/I is
recommended as 'To-Be-Considered" and is the numerical water
quality objective unless an alternate standard acceptable to the
Regional Board is proposed. This is the USEPA recommended
health advisory for toxicity other than cancer.
Napthalene is not a COPC for OU 3. Note that IT Corp. has sampled
for napthalene in and around the OU 2 plume and the results have been
nondetect (see "OU 2, Routine Plume Monitoring Informal Report,
September 1997," page 9). The use of napthalene as a surrogate
COPC is not an appropriate precedent to set in this ROD. Note that
text has been added to the ROD to indicate sampling frequency and
analyte selection for the long term monitoring program may be
modified as the program progresses (see response to Comment 23).
Dieldrin must be added to the table. A value of 0.0022 ug/I is
recommended as "To-Be-Considered" and is the numerical water
quality objective unless an alternate standard acceptable to the
Regional Board is proposed. This is the Cal-EPA cancer potency
factor as a water quality criteria.
D.4-3
-------
RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
Response:
Comment No. 11:
Response:
Comment No. 12:
Response:
Comment No. 13:
As agreed during the RPM Meeting on September 17, 1997, the
dieldrin that has been detected in wells in the eastern portion of the
base are not currently considered part of OU 3; therefore, dieldrin has
not been added to the table. Text has been added to Section 2.1.1
(Description of Operable Units) to state that the dieldrin detected in
wells in the eastern portion of the base is not considered part of OU 3
and will be addressed as part of another OU.
The ROD must indicate that collection of confirmation samples at
Sites WP-17, OT-51, and FT-19 is required to verify that the soil
cleanup levels indicated in Figures 9 and 10 are attained. Please
correct the 20 foot above ground water cleanup level shown on
figure 10 from 125 ug/kg to the correct numerical value.
Text has been added to Section 2.6.2 to state that "prior to closure of a
TPH/VOC site for which a remedy has been implemented,
confirmation samples (soil and/or vapor to estimate soil
concentrations) would be collected as necessary to demonstrate that
soil cleanup levels presented on Figure 9 are achieved." Note that this
section precedes the description of alternatives for the TPH/VOC sites.
The description of alternatives also indicates that confirmation samples
(soil and/or vapor) will be collected to confirm that remediation goals
have been achieved.
Figure 10 has been revised to state the correct value of 12.5 ug/kg.
The ROD must indicate that the active remediation systems (soil
vapor extraction and bioventing) will operate so long as the
systems continue contaminant mass reduction in a manner that is
technically and economically feasible.
Text has been added to Section 2.6.2 to state that based on the
remediation goals, a remedy would be implemented and operated until
the mass of contaminants remaining was such that no impact to
groundwater was anticipated.
Recently Board staff sent the Air Force a letter dated June 27,
1997 requesting a Preliminary Assessment/Site Investigation
(PA/SI) for the occurrence of the pesticide dieldrin in wells located
adjacent to Landfill Site LF-39. Dieldrin is present at levels of
approximately 0.12 ug/l. The draft ROD indicates that No Further
Action is appropriate based on the Air Force contention that Site
LF-39 was never a landfill. This request for additional site
information is not made at the "llth hour** as indicated by the Air
Force during the June 30, 1997 meeting. Board staff have
D.4-4
-------
Response:
RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
previously indicated that the western portion of the landfill
beneath base housing was not properly investigated, that No
Further Action was not appropriate, and that dieldrin was of
concern (May 2,1995 Board staff comments on the OU 3 Remedial
Investigation/Feasibility Study). The ROD must provide
supporting rationale for the recommendations made. As agreed to
during the June 30,1997 meeting, the ROD may include a remedy
for Site LF-39 that indicates long term monitoring for pesticides
will be conducted in the affected wells. The ROD should indicate
that a contingent remedy will be evaluated if: 1) water production
causes plume movement or 2) if the PA/SI results indicate a need.
The PA/SI may be conducted outside of OU 3, allowing the OU 3
ROD to be completed and decisions related to the dieldrin in
groundwater to be made outside of OU 3.
LF-39 is proposed for no further action (NFA) based on site-specific
data. Because dieldrin is located in wells upgradient of LF-39, this site
is not considered a source. Therefore it is appropriate that LF-39 be an
NFA site because dieldrin was not found in site soils.
The ROD does not make a statement regarding LF-39 never being a
landfill. All comments to the OU 3 RI/FS Reports were addressed in
writing and are presented in appropriate appendices to those reports.
These comments were provided to the RPMs with the final submittal.
As agreed during the RPM Meeting on September 17, 1997, the
dieldrin that has been detected in wells in the eastern portion of the
base (in the vicinity of LF-39) are not currently considered part of OU
3; therefore, it is not presented in this ROD. However, text has been
added to Section 2.1.1 (Description of Operable Units) to clarify this
point
Comment No. 14:
Response:
Comment No. 15:
The ROD must indicate that the abandoned well casing
downgradient of Site OT-51 will be properly sealed and
decommissioned. Please refer to Board staff memorandum dated
February 2, 1995 with information provided to the Air Force
regarding appropriate decommissioning methods.
Section 2.6.4.2 has been revised to state that the preferred alternative
for OT-51 includes the decommissioning of the abandoned well
downgradient of the site.
The ROD must clarify a number of issues for the Site OT-51 JP-4
plume comments, 16 to 19 pertain to this issue.
D.4-5
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RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
Response:
Comment No. 16:
Response:
Comment No. 17:
Response:
Comment No. 18:
Response:
Comment No. 19:
See response to Comments 16 through 19.
ORC is proposed as a contingent remedy for the Site OT-S1 JP-4
ground water plume. Based on information in the Basewide
Groundwater Monitoring Report for the February 1997 Sampling
Event, dated June 1997, prepared by Montgomery Watson, long
term monitoring of the JP-4 plume is appropriate.
Section 2.6.4.2 states that the preferred alternative for OT-51 includes
long term monitoring.
The criteria that will be used to determine when the contingent
remedy will be implemented must be stated. Board staff have
previously indicated that natural attenuation is acceptable if
plume stability is demonstrated and concentration reductions
occur as expected (May 5, 1997 Board staff memorandum with
comments on the draft OU 3 Proposed Plan and Staff Report
dated April 1997).
As agreed during the conference call between the RWQCB, USAF.
DISC, and Montgomery Watson on October 14, 1997, the text has
been modified where appropriate to state that the implementation of
the oxygen releasing chemicals would be contingent on the continued
reductions of COPCs in groundwater in a reasonable time frame. Data
collected as part of the basewide long-term monitoring program have
shown that the plume is characterized and concentrations are being
reduced.
The expected duration to attain cleanup to water quality
objectives must be stated. This duration calculation must include
all assumptions used.
s
Based on best engineering judgment, it is anticipated that the
groundwater will be remediated to within acceptable levels within 5
years. The is primarily based on the fact that the source is being
removed by installation of a bioventing system and the recent
basewide groundwater monitoring data indicating that levels of
COPCs are decreasing (Montgomery Watson, 1996 d, e, f and 1997 d,
e, f)- The text of the ROD has been revised to cite this recent
groundwater monitoring data.
Currently there are insufficient groundwater monitoring points
downgradient of the plume. Additional downgradient
D.4-6
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RESPONSES TO RWQCB JULY 1.1,1997 COMMENTS (Continued)
groundwater monitoring points are necessary to verify site
conditions during monitoring prior to closure.
Response: The draft ROD discussed the need for additional monitoring points
downgradicnt of Site OT-51 in Sections 2.6.2.1 and 2.6.2.5. In
addition. Table 20 included 2 wells as part of the FS cost estimate. An
additional statement has been added to Section 2.6.4.2 that one or two
wells will be installed to satisfy the long-term monitoring requirement
for Site OT-51.
Comment No. 20:
Response:
Comment No. 21:
Response:
Comment No. 22:
Response:
Because the closure activities at the landfill sites are complete, the
ROD should include references to Table 4 (Landfill ARARs)
describing the compliance status of each ARAR. This will allow a
determination of which ARARs apply during the post-closure
maintenance and monitoring phase.
Text has been added to Section 2.9 (Site Status) that "as part of the 5-
year review, the status of compliance with ARARs will be evaluated
and reported."
The ROD must clarify when the landfill post-closure maintenance
and monitoring plan will be submitted to meet the substantive
requirements of the following section of the California Code of
Regulations, Title 23, Chapter 15: §2580(a), §2581(c), and §2597.
The draft "Site Closeout Report for DP-03, DP-04, LF-12, LF-14, and
the Southeast Disposal Area" was submitted in June 1997. The
proposed maintenance activity schedule is presented in this report and
is summarized on Table 12-3 of the Closeout Report. This document
is referenced where appropriate in the text of the ROD.
The ROD must include information to determine if a landfill
release has occurred. Board staff have previously indicated that
the Water Quality Protection Standard (WQPS) must be specified
in the ROD.
As agreed during the conference call between the RWQCB, USAF,
DTSC, and Montgomery Watson on October 14, 1997, text has been
added in Section 2.9 as follows; "Water Quality Protection Standards
(WQPS) will be developed to assess whether there has been a release
from the landfills. The WQPS will be developed within 6 months of
the signing of this ROD and will be based on the available
groundwater data to establish baseline values for which future
sampling results will be compared."
D.4-7
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RESPONSES TO RWQCB JULY 11,1997 COMMENTS (Continued)
Comment No. 23:
Response:
Comment No. 24:
Response:
The Site Close-out Reports for DP-03, DP4M, LF-12, LF-14 and
the Southeast Disposal Area, dated June 1997, provided by
Montgomery Watson, Section 12, Table 12-2, gives useful
information regarding analyte selection. The elements of long
term monitoring should be incorporated in the ROD, giving
flexibility for future changes.
Text has been added to Section 2.9 to state that "as part of the
monitoring program, monitoring wells associated with the landfills are
sampled and analyzed for halogenated volatile organic compounds
(HVOCs) (EPA method 8260 suggested), and landfill indicator
parameters (pH, total dissolved solids, chloride, sulfate, and nitrate).
The sampling frequency and analyte selection may be modified as the
program progresses."
As discussed during July 1,1997 meeting, for long term detection
monitoring at landfills, it is not necessary to sample for metals
unless sufficient data has not yet been collected for determining
the WQPS. It is necessary to monitor for volatile organic
compounds in all landfill detection monitoring wells by USEPA
method 8260.
See response to Comment 23.
D.4-8
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Appendix E
MONTGOMERY WATSON
m
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APPENDIX E
RESPONSES TO AGENCY COMMENTS TO NOVEMBER 1997 DRAFT FINAL ROD
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RESPONSES TO USEPA COMMENTS
DATED DECEMBER 5,1997 ON THE NOVEMBER 1997
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
Page 1-3, Revise EPA's approval signature to the following:
Daniel D. Opalinski
Chief, Federal Facilities Cleanup Branch
Environmental Protection Agency
Region IX
Agree. The text has been modified accordingly.
Pages 2-17/18, y*/4* respective paragraphs. EPA's comment
number one on the draft ROD concerning human health risk was
not adequately addressed. There are still instances where the
ROD cites the remedy selection was based mainly on human
health risk, specifically with DP-03/04. Again, human health risk
was only one of several, but not the main deciding factor used for
remedy selection. This must be made clear throughout the
document as stated in our previous comments in the FS and the
Draft ROD comments.
The sentences in question have been removed from the document as
agreed during the December 23, 1997 RPM meeting.
Text in Section 2.9 (Current Site Status) of the November 1997 Draft
Final ROD states that "in an effort to accelerate the remedial process,
to minimize present and future environmental risks, reduce potential
impacts to groundwater, and facilitate timely transfer of property to the
community, cleanup activities have been initiated under the direction
of the USAF, at some of the sites presented in this ROD" to clarify that
site risk is not the only reason the RPMs agreed to implement remedial
actions.
The section referenced is 2.5.1, which summarizes the RI/FS activities
and presents the risk assessments performed. The sites were
considered in the OU 3 FS because of the exceedence of risk (human
and ecological). Remedy selection is based on the nine CERCLA
criteria as detailed in die subsequent Section 2.5.3.
El-1
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RESPONSES TO USEPA DECEMBER 5,1997 COMMENTS (Continued)
Comment No. 3:
Response:
Comment No. 4:
Response:
Section 15.4.2, first bullet, "grading existing soil cover to a slope
of 1.5 to 25 percent to promote surface runoff...wastes." Delete the
underlined as shown, and any reference to same throughout the
document, because our official landfill discussions only involved 1
to 3 percent grade. Although you responded to our concerns
about LF-14 that only "field changes" occurred, we disagree with
your response resulting that no changes were made withouit our
knowledge. Because of the steep slope on the landfill caps
modified during its construction, a contingency plan should
address potential erosion problems in the Operations and
Maintenance document.
Agree. The text has been modified to remove the statement specifying
1.5 to 25 percent slope.
Additionally, Section 2.5.4.2 been modified to state that a contingency
plan will be implemented should the remedy no longer be protective of
human health and the environment. Contingency plans will be
described as necessary as part of the O&M documentation.
EPA's draft ROD comment number six concerning land use
applies. The known land use restrictions, for the OU 3 sites,
should be described in more detail in the final ROD. If this is not
possible, the ROD should state that the language and form of the
land use restrictions will be provided to EPA for approval prior to
implementation. The sites for which land use restrictions are part
of the remedy are:
Sites DP-03 and DP-04 (page 2-40)
Sites LF-13, LF-14, and SEDA (page 2-41)
Site LF-44 (page 2-41)
Site FT-19c , (page 2-69)
Sites WP-17, FT-19a, OT-51 (soil) (page 2-70)
In addition, the description of Site OT-51 (groundwater) on page
2-69 mentions land use restrictions, but there is no parallel
reference in the detailed description on page 2-70. Assuming that
land use restrictions are intended to be part of the remedy alt Site
OT-51 (groundwater), appropriate language should be added to
page 2-70.
The text has been modified to contain the language agreed upon at the
December 23, 1997 RPM meeting. The sections describing the
selected remedy for each of the sites listed above (i.e., Sections 2.5.4.2
and 2.6.4.2) have been revised to include the agreed upon language
E.l-2
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RESPONSES TO USEPA DECEMBER 5, 1997 COMMENTS (Continued)
specific to the alternatives selected (i.e., landfill covers, bioventing,
opportunity to rcview ** language for
fAfcte typographical error in the comment: LF-13 should be LF-12.)
CommentNo.5: M--y Watson (MW> requested
m «* In *!y *• operation systems for various
TPH/VOC sites being remediated. Since mid 1995, the recurring
message by MW/GAFB was that these sites would be c£n™n
two years." GAFB should provide the rationale in the RD/RA
doT1^ ? !" ^ Why "* System «• ta -^"^ * ^ut
dZ'^118 ^f November RPM meetin8' ^ want«« ^ *«
down the moventing system at WP-17. EPA cannot concur with
R^D £J« rt"
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RESPONSES TO URSG CONSULTANTS COMMENTS
DATED DECEMBER 5,1997 ON THE NOVEMBER 1997
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL COMMENTS
Comment No. 1:
Response:
Response:
Response:
Section 2.6.4.2, Detailed Description of the TPH/VOC Site
Preferred Alternative, page 2-69.
a.) Site FT-19c, last bullet: "collection of confirmation samples
(soil or vapor [to estimate soil concentrations]) to assess
remedy completion."
Confirmation sampling should reveal concentrations of COPCs
in both soil vapor and soils. It is recommended that the phrase
"soil or vapor" be replaced by "soil and vapor."
Agree. The text has been revised to state "soil and vapor" samples will
be collected to assess remedy completion.
b.) Sites WP-17, FT-19a, OT-51 (soil), page 2-70.
The above comment applies to these sites.
See response to Comment la.
Third bullet: "implementation of long-term groundwater
monitoring in accordance with the basewide long-term
groundwater monitoring plan (Montgomery Watson, 1996c).
The 1996 basewide long-term groundwater monitoring plan
was never received and approved. This bullet should be
revised and state that a basewide long-term groundwater
monitoring plan will be developed for approval to address
groundwater quality concerns at these sites. This comment
also applies the second bullet under site OT-51 (groundwater),
page 2-70.
Please note that the base has been operating under an approved plan
(Montgomery Watson, 1995c and I996c). However, for clarity this
reference has been removed from the page in question. The 1996 plan
is now referenced in the document only when discussing specific
sampling events that have already occurred.
E.2-1
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RESPONSES TO URSG DECEMBER 5, 1997 COMMENTS (Continued)
When referring to future long-term monitoring in general, the text
throughout the document has been modified to refer to "an approved
long-term groundwater monitoring plan for GAFB."
Sections 2.9.1.4 and 2.9.2.7 discuss long-term monitoring and state
that "sampling frequency and analyte selection may be modified as the
program progresses."
d) Sites OT-51
The Remedial Investigation Report/OU 3 indicates that a
Hydropunch sample (groundwater at SBS-25) contains
benzene of 1,000 ug/L. GAFB should cite that additional
contingency plans may be required in case implementation of
oxygen release chemicals show little effect A potential
anaerobic state at the site would make ORC ineffective.
Response: (Note: no comment "c" was received. The numbering system has been
left unchanged to be consistent with the original comments submitted
bytheUSEPA.)
At the request of the RWQCB, the Draft Final ROD is written such
that the use of oxygen-releasing chemicals (Alternative 11) is a
contingency and natural attenuation is the final remedy (see Section
2.6.4.2). The text has been modified where appropriate to clarify this
decision. Additionally, note that an anaerobic state is a condition
under which the use of oxygen releasing chemicals would be
considered.
Regarding HydroPunch® sampling, Section 2.6.1.5 documents in the
Draft Final ROD that HydroPunch® samples were collected in borings
SBS-25 and SBS-27. This information is further detailed in the OU 3
RI, finalized in April 1996. This document explains that
HydroPunch® data is Level HI (nondefinitive) and therefore is suitable
for screening purposes only. The HydroPunch® samples were the
basis for monitoring well placement.
Comment No. 2:
Section 2.7.1, Summary of Site OT-69 Characteristics and Risk
Assessment, page 2-73.
First paragraph, line 1: "Site OT-69 consists of the TCE and PCE
groundwater contamination that was detected in the flight line and
operations support, facilities area."
E.2-2
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RESPONSES TO URSG DECEMBER 5,1997 COMMENTS (Continued)
Response:
Comment No. 3:
Response:
Locations of TCE/PCE contaminated areas were not clear to the
reader even though Figure 14 is referenced later in this paragraph.
The ROD is a primary document and is meant to be stand-alone.
GAFB should indicate the location of each TCE/PCE
contaminated area in the text and provide a name for each area so
that the reader may distinguish one from the other.
Formal "names" for the plumes have not currently been identified. As
agreed during the December 23, 1997 RPM Meeting, Figure 14 has
been revised to show select affected wells to aid in plume
identification.
Section 2.7.4.2, Detailed Description of the Site OT-69 Preferred
Alternative, page 2-84.
a) Line 3: "In addition, continued monitoring of the natural
attenuation plume will be achieved through annual
groundwater monitoring of approximately 10 wells'*
The frequency of monitoring and number of wells should be
deleted from ROD and be stated in a site-specific groundwater
monitoring plan.. GAFB should state that the site-specific
groundwater monitoring plan will be developed to address
monitoring details for OT-69.
Agree. The text has been modified to remove "approximately 10
wells."
When referring to future long-term monitoring in general, the text
throughout the document has been modified to refer to "an approved
long-term groundwater monitoring plan for GAFB."
Sections 2.9.1.4 and 2.9.2.7 discuss long-term monitoring and state
that "sampling frequency and analyte selection may be modified as the
program progresses."
b) The ROD should cite a contingency plan if TCE levels remain
high at OT-69 (e.g., well MW-72). The contingency plan can
be developed in the RD/RA document that should include the
following: (1) which contaminated areas will be involved, (2)
cite the predicted concentrations at each well, and (3) rationale
for any active remedial actions. It is recommended that active
remedial actions be taken when measured TCE concentrations
E.2-3
-------
RESPONSES TO URSG DECEMBER 5,1997 COMMENTS (Continued)
is 50 percent higher than the predicted concentration (mean
value).
Response: Agree The text has been modified to state, "More active remedies
wouJd be considered as a contingency if the natural attenuation remedy
«s not restoring water quality in a timely manner. The criteria under
which active remediation would be initiated at Site OT-69 were
detailed in a memorandum prepared by IT which is included as
Appendix B to this ROD (IT, 1995b)... If it is determined that natural
attenuation is not restoring water quality, more active remedies would
be assessed as part of the 5-year review process and may include
alternatives assessed as part of this ROD or additional new
technologies that may become available."
E.2-4
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•Tr
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RESPONSES TO DEPARTMENT OF TOXIC SUBSTANCES CONTROL COMMENTS
DATED DECEMBER 2,1997 ON THE NOVEMBER 1997
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
GENERAL COMMENTS
Comment No. 1: The DTSC concurs with the Regional Water Quality Control
Board, Lahontan Region, comments.
Response:, Comment noted.
Comment No. 2: High quality analytical samples will be required in order to
demonstrate that the remedial action objectives have been
satisfied for all remedies.
Response: Agree. The ROD identifies where analytical samples are proposed
(i.e., long-term groundwater monitoring, confirmation samples for
TPH/VOC sites).
SPECIFIC COMMENTS;
Comment No. 1: Page 2-40, para. 3. The ROD must clearly specify in general
terms that Operations and Maintenance (O&M) will be
implemented as outlined in a regulatory agency approved plan.
Response: As agreed during the December 23, 1997 RPM meeting. Section
2.5.4.2 has been modified to state that contingency plans will be
described as necessary as part of the O&M documentation. Section
2.9.1.5 has been modified to state that "if instances of burrowing
animal problems continue to persist, an appropriate contingency plan
will be developed and presented in a subsequent O&M document."
In addition, Section 2.5.4.4 references ongoing O&M activities and
Appendix C states that a Post-Closure Monitoring and Maintenance
Plan will be developed for the OU 3 landfill sites.
Comment No. 2: Page 2-52, para. 5. This section addressees groundwater
protection levels as outlined in Figures 9 and 10. Two revisions
must he made to this section:
E.3-1
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RESPONSES TO DTSC DECEMBER 2,1997 COMMENTS (Continued)
(a) First, it must be made clear that these levels are purely for
groundwater quality protection. This must be so indicated
in the text and hi the figures.
Response:
Comment No. 3:
Response:
Comment No. 4:
Response:
Comment No. 5:
(b)
Second, these levels appear to be unacceptable for human
and ecological health. The risk, especially at the surface
must be evaluated with a human and ecological health risk
assessment based on high quality data points which are to
be obtained when the remedies have run their course.
This risk assessment must take into account all pathways
and chemicals of potential concern.
*
Ultimately any remedy which is not deemed by a
regulatory agency to be protective is inadequate and must
be further remedied.
(a) Agree. The text has been modified accordingly.
(b) Agree. The remedy must be protective.
Page 2-53, para. 2. The same comment as Page 2-52 above
applies to this paragraph. '
See response to Comment 2.
Page 2-67, para. l. FT-19 groundwater does in fact have
groundwater contaminated with TCE above regulatory
thresholds. The agreement is to monitor nearby wells and take
any necessary actions. The ROD should include language state
that the groundwater monitoring plan which is implemented for
FT-19 must meet all the remedial action objectives either per
Operable Unit or on a basewide basis.
As discussed in Section 2.6.1.2, the TCE in the groundwater beneath
~1S P8It of OU L For this reason, it is not addressed in the OU
Response:
Page 2-69, para. 4, fifth bullet. The current bullet 5 spells out
that soil or vapor samples will be obtained for confirmation
purposes. Replace the word "or" with the word "and." Both are
needed for site closure.
Agree. The text has been modified accordingly.
E.3-2
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RESPONSES TO DTSC DECEMBER 2,1997 COMMENTS (Continued)
Comment No. 6:
Response:
Comment No. 7:
Response:
Page 2-70, para. 1. The same comment as for page 2-69 above
applies for sites WP-17. FT-19c and OT-51. In addition, the
OT-51 groundwater site may require a contingency plan if the
preferred alternative proves inadequate.
See Response to Specific Comment 5.
The text describing the selected remedy for OT-51 groundwater
states that the remedy includes "implementation of oxygen releasing
chemicals as a contingency if COPCs in groundwater do not
decrease to water quality goals within a sufficient time frame."
Section 2.9.2.4 goes into further detail by stating "If subsequent
rounds of long-term monitoring do not continue to show the trend of
decreasing levels of COPCs, the contingent remedy of installation of
oxygen-releasing chemicals described for Alternative 11 (Section
2.6.2.6) will be implemented."
Page 2-84, para. 3. The number of wells and the frequency of
sampling should be established in an appropriate long term
monitoring plan which addresses the remedial action objectives
for each ROD or basewide. Please delete "approximately 10
wells."
In addition, a contingency plan should be included for OT-69
should groundwater levels remain above action levels.
Agree. The text has been modified to remove "approximately 10
wells."
Regarding the contingency plan for Site OT-69, as agreed during the
December 23, 1997 RPM meeting, this comment has been addressed
as follows:
1) The text in Section 2.9.2.5 and has been modified to state "the
criteria under which active remediation would be initiated at Site
OT-69 were detailed in a memorandum prepared by IT which is
included as Appendix B to this ROD." This memorandum
includes the plume maps and concentration predictions made in
October 1995.
2) The text in quotations from the RWQCB's Specific Comment 3
has been included in Section 2.9.2.5.
E.3-3
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RESPONSES TO DTSC DECEMBER 2,1997 COMMENTS (Continued)
3) The "Criteria for evaluating data" and "Financial assurances"
sections of IT's November 1995 memorandum have been
summarized in Section 2.9.2.5.
Comment No. 8: page 2-89, para. 7. The discussion of the agreed upon remedy
for OT-69 is incomplete. The section is missing a summary of
the Internationa] Technology Memorandum dated November 6,
1995 which spells out the detailed methodology from passive
monitoring to active remedy. The ROD must include this
information.
In addition, the ROD must include the specific land use
prohibitions regarding the placement of water production wells
In the upper aquifer in the vicinity of the flightline. These land
use prohibitions must be agreed to and approved by the
governing regulatory agencies. The release from such
prohibitions must be agreed to, in writing by the Department of
Toxic Substances Control or the Lahontan Regional Water
Quality Control Board.
Response: See response to Specific Comment 7.
Regarding land use restrictions. Section 2.7.4.2 (Detailed
Description of the Site OT-69 Preferred Alternative) states that the
remedy will "include land use restrictions prohibiting installation of
wells for domestic purposes in the affected aquifer and deed
restrictions prohibiting use of contaminated water." In addition,
Section 2.7.4.2 refers the reader to Section 2.9.2.5 for further detail.
E.3-4
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RESPONSES TO LAHONTAN REGIONAL WATER QUALITY CONTROL BOARD
COMMENTS DATED DECEMBER 3,1997 ON THE NOVEMBER 1997
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
SPECIFIC COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
Comment No. 3:
Page 1-2, Section 1.4, Description of Selected Remedies. Please
delete the phrase "the USAF, the USEPA, and the Sate of
California have determined." Section 1.2 of the ROD states that
the State of California concurs with the remedy. The role of the
State is to concur with, not approve, the selected remedy. The
statement that the State "determined" a final remedy would
suggest that the State is making a discretionary decision subject to
the California Environmental Quality Act.
Agree. The text has been modified to state that the USAF has
determined the final action with the concurrence of the regulatory
agencies.
Page 2-53, Section 2.6.2, Description of TPH/VOC Site
Alternatives. Please change the last sentence of the paragraph on
this page as follows. "Prior to closure of a TPH/VOC site for
which a remedy has been implemented, confirmation samples (soil
or vapor [to estimate soil concentrations]) would be collected as
necessary to demonstrate that no farther impact to groundwater
remains using the soil levels presented" in Figure 9 and 10 as a goal
sail cleanup levels prtjtnt an Flguit 9 arc athitttd." As indicated
in the prior sentence, site closure is dependent on threat to water
quality and the numerical levels shown in the figures are a goal to
meet the cleanup objective.
As agreed during the December 23, 1997 RPM meeting, the text has
been modified as follows: "Prior to closure of a TPH/VOC site for
which a remedy has been implemented, confirmation samples (soil and
vapor) would be collected as necessary to demonstrate that soil
cleanup levels presented on Figures 9 and 10 are achieved. If
contamination remaining in soil can be demonstrated to have no
impact to groundwater quality, concentrations remaining in soil may
exceed the numerical values presented in Figures 9 and 10, and the site
may be considered for closure."
Page 2-89, Section 2.9.2.5, Site OT-69. The discussion of the
remedy agreed to by the Regional Board is incomplete and does
E.4-1
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RESPONSES TO RWQCB DECEMBER 3,1997 COMMENTS (Continued)
not reference the active contingent remedy spelled out in the
November 6,1995 Memorandum prepared by IT Corp, on behalf
of the Air Force. The ROD must clearly indicate the scope of the
Site OT-69 remedy agreed to the Regional Board. The ROD
should include the following language:
"The monitoring and response plan proposed by the Air Force
was developed based upon computer modeling simulations that
estimate specific future concentrations in particular wells
projecting that water quality objectives will be restored in about
50 years. If the expected reductions do not occur in the projected
time frame, plus or minus 15% of the projected concentration,
then the data will be evaluated. If the data are less than 2
standard deviations of the projected concentrations then
monitoring may continue. If the data are greater than two
standard deviations, then the wells will be resampled and the data
re-evaluated. If the data are still greater than two standard
deviations of the original projected concentrations, then an active
remedy consisting of Air Sparging with Soil Vapor Extraction will
be implemented or the agencies will reach consensus regarding a
technical decision for implementing some other appropriate active
remedy. The ROD will be amended at that time to specify the
ARARs for the contingent remedy."
In addition, the ROD must include a map of the plumes and tables
with predicted TCE concentrations in selected wells. The tables
must clearly indicate that projected future concentrations are
based upon data collected in the summer of 1995 and the time
projections were made in October 1995 as a reference date. The
monitoring frequency and specific wells niay vary as determined
by remedial project managers.
The ROD must specifically indicate that the Air Force will provide
for land use prohibitions regarding the placement of water
production wells in the upper aquifer in the vicinity of the
flightline. Such land use restrictions must be included in any
parcel, lease or deed and recorded with the County. The specific
language contained in the site parcel lease or deed restriction must
be reviewed and approved by the regulatory agencies. The ROD
must indicate that a Well Exclusion Zone, administered by San
Bernardino County will be considered and implemented, if
feasible. The State Department of Toxic Substances Control or
Regional Water Quality Control Board, Lahontan Region must
E.4-2
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RESPONSES TO RWQCB DECEMBER 3,1997 COMMENTS (Continued)
approve removal of the deed restriction. Further, the ROD must
include the Federal Certification of ensuring that financial
resources will be obtained to implement the active contingent
remedy. Refer to 22250, Title 27, Cal. Code of Regs for the
requirements of Federal Certification.
Response:
Comment No. 4:
Response:
As agreed during the December 23, 1997 RPM meeting, this comment
has been addressed as follows:
1) The text in Section 2.9.2.5 has been modified to state "the criteria
under which active remediation would be initiated at Site OT-69
were detailed in a memorandum prepared by IT which is included
as Appendix B to this ROD." This memorandum includes the
requested plume maps and concentration predictions made in
October 1995.
2) The text in quotations (with revision for consistency and clarity)
has been included in Section 2.9.2.5.
3) The "Criteria for evaluating data" and "Financial assurances"
sections of ITs November 1995 memorandum have been
summarized in Section 2.9.2.5.
4) Regarding land use restrictions, Section 2.7.4.2 (Detailed
Description of the Site OT-69 Preferred Alternative) states that the
remedy will "include land use restrictions prohibiting installation
of wells for domestic purposes in the affected aquifer and deed
restrictions prohibiting use of contaminated water." In addition,
Sections 2.7.4.2 refers the reader to Section 2.9.2.5 for further
detail.
Table 4, ARARs for GAFB OU 3 Landfill Sites, DP-03, DP-04, LF-
12, LF-14 and the SEDA. Board staff previously indicated to the
Air Force that Title 27, Cal. Code of Regs was recently adopted to
replace portions of Titles 14 and 23, Cal. Code of Regs. The
appropriate new section numbers should be cited in this table.
Otherwise, the following footnote should be placed at the end of
the table and flagged. "These sections of Title 14 Cal. Code of
Regs and Title 23 Cal. Code of Regs have been recodffied into Title
27 Cal. Code of Regs. See Title 27 Cal. Code of Regs for the new
equivalent section numbers that apply."
The above footnote has been added to Table 4 (on page 10 of 10) with
minor revision for consistency and clarity.
E.4-3
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RESPONSES TO RWQCB DECEMBER 3,1997 COMMENTS (Continued)
Comment No. 5:
Response:
Comment No. 6:
Response:
Table IS, page 1 of 9, fourth item [SWRCB Resolution 92-49J.
Please delete the last sentence in the description which states "In a
separate forum, the Department of Defense (DoD), USEPA Region
IX, and the State are attempting to globally resolve the ARAR
status of SWRCB Resolution 92-49, including Section III.G, for all
DoD sites within the State." Board staff understand that there are
no current efforts in progress, or planned, to resolve the ARAR
status of SWRCB Resolution 92-49.
The table has been modified accordingly.
Table 15, page 6 of 9, second item [NPDES Stormwater Program].
Please Include the following sentence after the existing sentence in
the description column. 'To comply with this requirement, the
Air Force must comply with the requirements contained in the
State General Industrial Storm Water Permit (Order No. 91-13-
DWQ, as amended by Order No. 92-12-DWQ, NPDES No.
CAS000001)." The State administers the federal NPDES
stormwater program.
The table has been modified accordingly.
E.4-4
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RESPONSES TO USEPA COMMENTS
DATED FEBRUARY 2,1998 ON THE NOVEMBER 1997
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
Comment No. 1:
Response:
Comment No. 2:
Pages 2-37 and 2-65, Selected Remedies. The DF ROD is
presented more like a FS rather than a decision document The
reader cannot easily identify the selected remedy for each site, the
main purpose of a ROD. Accordingly, the ROD should clearly
document the selected remedy along with the estimated cleanup
time for sites in active remediation. Sites that have already been
remediated should show the dates of their completion.
The presentation of the OU 3 ROD is consistent with the USEPA's "A
Guide to Developing Superfiind Records of Decision" (dated May
1990, Directive: 9335.3-02FS-1). In accordance with this guidance
document, the elements of the FS are summarized (i.e. summary of site
characteristics and risks, descriptions of alternatives, comparative
analysis of alternatives using the nine CERCLA criteria, and the
selected remedy). This guidance document is now cited in Section 1.2.
Statements have been added to Sections 2.5.4 and 2.6.4 explicitly
stating the "selected remedy" for each site and the estimated duration
of cleanup or date of remediation completion.
The selected remedies for OU 3 sites are also identified in other places
in the document as follows: 1) Table 1 summarizes all 60 OU 3 sites
and identifies the selected remedy, and 2) Section 2.9 summarizes the
current site status and presents the action that has occurred, dates that
remedial action was performed, and dates of completion (where
applicable).
Pages 2-40/41/69/70, various OU 3 sites. The revised tend use
comment developed during the December 22, 1997 meeting,
"implementation of access and land use restrictions such as
preventing construction activities that would impair the integrity
of the existing cover," is a good start, but still falls short of meeting
CERCLA and DoD requirements. The Under Secretary of
Defense's memorandum of July 25, 1997 (re: land use), which
outlined CERCLA requirements, requires the following specific
land use language in the ROD:
- Identify future land use assumptions or objectives.
E.5-1
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RESPONSES TO USEPA FEBRUARY 2,1998 COMMENTS (Continued)
- Specify land use restrictions and how they will be enforced
(e.g., deed restrictions, easements, inspection/monitoring,
zoning, etc.). Potential deed restrictions should also be
documented (e.g., no residential use, no groundwater use for
drinking, etc.). Refer to our December 5* letter for more
guidance.
Response The purpose of the meeting held on December 23, 1997 during which
the OU 3 ROD was discussed was to agree to the final language that
would be acceptable to all agency RPMs. During that meeting, the
comments from the USEPA's letter dated December 5, 1997 were read
and specific language to address each comment was developed.
In addition to the language agreed upon during the December 23, 1997
meeting, the text in the above referenced sections has been modified to
include language suggested by the USEPA in subsequent telephone
conversations with the USAR This includes notations that signage
will be posted on the fences at the landfills warning against
unauthorized vehicular traffic, restricting access to equipment at the
TPH/VOC sites, and preventing installation of monitoring or injection
wells accept for environmental purposes at the landfill and TPH/VOC
sites.
Comment No. 3:
Response:
Page 2-88, Ecological Monitoring Plan.
- Because of desert tortoise habitat identified in a 1990 survey,
GAFB should coordinate Section 7 consultation with the UJS.
Fish and Wildlife Service, and the State Fish and Game, to
develop a sound ecological monitoring plan.
• Section 2.9.1.5, 3" paragraph, last sentence: "If the burrows
are constructed by species common to the area,...conditJon."
This seems to imply that burrows made by species not common
to the area would not be repaired. Accordingly, the section,
"constructed by species common" should be deleted and
replaced with "If burrows are found in the area, the
burrows^.condition."
- A three month lapse time is not responsive in maintaining
landfill cap integrity for burrowing problems. Burrows in the
cap should be repaired as soon as possible to minimize
ecological risk problems.
- The ecological monitoring plan will be included as part of separate
remedial action documentation. Appendix C of the Draft Final
E.5-2
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RESPONSES TO USEPA FEBRUARY 2,1998 COMMENTS (Continued)
ROD identifies the action items to meet ROD requirements, which
included developing an OU 3 Landfill Post-Closure Maintenance
and Monitoring Plan.
- Details regarding the ecological monitoring plan will be presented
in the OU 3 Landfill Post-Closure Maintenance and Monitoring
Plan discussed above.
- The text as written indicates that minor repairs may be
implemented in 30 days. Additional details regarding the
ecological monitoring plan will be presented in the OU 3 Landfill
Post-Closure Maintenance and Monitoring Plan discussed above.
E.5-3
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X
Appendix F
MONTGOMERY WATSON
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APPENDIX F
RESPONSES TO AGENCY COMMENTS TO FEBRUARY 1998 DRAFT FINAL ROD
3
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RESPONSES TO LAHONTAN REGIONAL WATER QUALITY CONTROL BOARD
COMMENTS DATED MARCH 24, 1998 ON THE FEBRUARY 1998
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
SPECIFIC COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
Comment No. 3:
Table 15, Title 27 Cal. Code of Regs (CCR) - Board staff indicated
that the note added to Table 4, also applies to Table 15. That note
states: "Sections of Title 14 CCR and Title 23 CCR have been
recodified into Title 27 CCR. See Title 27 CCR for the new
equivalent numbers that apply." Please include this statement at
the end of Table 15 or indicate the correct Title 27 section
numbers in Table 15.
The statement previously included on Table 4 has been added to Table
15.
Tables 4 and 15, Footnote versus Note - The above referenced
statement was added to Table 4 as a "Note". Board staff strongly
believe that this statement should be included to Table 4 (and 15)
as a referenced footnote, to provide the proper emphasis. This is
because the current state standards are not as indicated in the
table. Title 23 currently only applies to hazardous waste. Board
staff provided the option of including the footnote rather than
revising the table (as preferred) to minimize the time spent in
finalizing this document Please include the above statement as a
footnote rather than a note.
The language previously included as a "Note" has been referenced
with a superscript "a" in the "Standard, Requirement, Criterion, or
Limitation" column of Tables 4 and 15 to reference the footnote
identified with a superscript "a" on the last page of the table.
Table 15, Inclusion of State Ground Water Standards for Cleanup
(Concentration Limits) - When the Applicable or Relevant and
Appropriate Requirements (ARAR) were negotiated between the
legal staff of the respective parties to the Federal Facilities
Agreement (FFA), Operable Unit Three did not contain Site OT-
69 (Small solvent plumes selected for natural attenuation).
Subsequent to the development of the ARAR tables, Site OT-69
was included with OU-3. Therefore, Section 2550.4
(Concentration Limits) must be added to Table 15. The correct
citation should be Title 27, § 20400. Please include reference to
F.l-1
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RESPONSES TO RWQCB MARCH 24,1998 COMMENTS (Continued)
this section in Table 15. <*
Response: The primary meeting to negotiate ARARs was held on August 20,
1996 at the USEPA offices in San Francisco, California. At that •/;
meeting, Section 2550.4 was deleted from the ARARs list for the
TPH/VOC sites and agreed to by all parties. Site OT-69 was part of
the discussion regarding the TPH/VOC sites.
F.I-2
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RESPONSES TO UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
COMMENTS DATED MARCH 19,1998 ON THE FEBRUARY 1998
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
SPECIFIC COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
Comment No. 3:
Response:
In Section 2.9.1.5., Ecological Monitoring For the Landfill Areas.
3rd paragraph, the next-to-last sentence states: "If the burrows
are constructed by species common to the area, the burrows will
be filled with native soil materials to restore the soil cover to its
original condition." This appears to mean that burrows will not
be repaired if the burrowing species are not common to the area.
When EPA questioned this language during the RPM meeting,
apparently inconsistent explanations were provided by
representatives of Montgomery Watson, to the effect that all
burrows would be filled, and/or that burrows used by special-
status species (such as burrowing owls or desert tortoises) would
not be filled. The section should be rewritten to make clear what
is intended. EPA's position is that all burrows should be filled.
The text has been modified accordingly.
In Section 2.9.1.5, 3rd paragraph, the last sentence should be
revised to specify that George AFB will coordinate with the State
Department of Fish and Game and the U.S. Fish and Wildlife
Service to develop the ecological monitoring plan as part of the
Operations and Maintenance document.
The text has been modified accordingly.
In Section 2.9.1.5,4th paragraph, EPA believes that a three-month
lapse tune is not responsive in maintaining landfill cap integrity
for burrowing problems. Burrows in the cap should be repaired
as soon as possible, when discovered during the scheduled landfill
inspections, to minimize ecological risks to burrowing mammals.
The text has been modified accordingly.
F.2-1
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RESPONSES TO UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
COMMENTS DATED MARCH 26,1998 ON THE FEBRUARY 1998
DRAFT FINAL RECORD OF DECISION FOR OPERABLE UNIT 3 SITES
GEORGE AIR FORCE BASE, CALIFORNIA
SPECIFIC COMMENTS
Comment No. 1:
Response:
Comment No. 2:
Response:
2.9.1.5., 3rd paragraph, page 2-106: delete the following in its
entirety; "If burrows are observed, the animals . . . O&M
document"
Replacement language: "The Air Force will consult with the State
Department of Fish and Game to develop a burrows management
protocol for the O&M document. A contingency plan for
recurring burrow problems and the specific details of the
ecological monitoring plan will be presented in the subsequent
O&M document."
The text has been modified accordingly.
2.9.1.5, 4th paragraph, page 2-107: delete the following in its
entirety; "An effort will be made to make repairs within 3 months
of the maintenance inspection, when possible."
Replacement language: "An effort will be made to make
revegetative repairs as soon as it is practical based on seasonal
timing."
The text has been modified accordingly.
F.3-1
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