PB97-964512
                                          EPA/541/R-97/134
                                          January 1998
    EPA  Superfund
            Record of Decision:
             Castle Air Force Base
             Merced, CA
             5/21/1997
U.S. EPA Region III
Regional Center for Environmental
 Information
   Arch Street (3PM52)

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United States Air Force
Installation Restoration Program
Castle Airport

Record of Decision for
Comprehensive Basewide - Part 1
Groundwater
FINAL
December 1996

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  Final Record
          of
     Decision
Comprehensive Base wide Program-Part 1
            *-•
       (Groundwater)

     Castle Air Force Base
       31 January 1997

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                                                            31 January 1997

                   FINAL RECORD OF DECISION
 COMPREHENSIVE BASEWTOE PROGRAM—PART 1 (GROUNDWATER)
                     CASTLE AIR FORCE BASE

                       TABLE OF CONTENTS

Tab      .                                                Section/Page

1.0   INTRODUCTION	.	.	....	..	.	...1-1

2.0   DECLARATION FOR THE RECORD OF DECISION	2-1
2.1   SITE NAME AND LOCATION	2-1
2.2   STATEMENT OF BASIS AND PURPOSE	2-1
2.3   ASSESSMENT OF THE SITE	2-2
2.4   DESCRIPTION OF THE REMEDY	2-2
     2.4.1  Selected Remedy:  Main Base Plume	;	2-3
     2.4.2  Selected Remedy:  East Base Plume	2-4
     2.4.3  Selected Remedy:  Castle Vista Plume	2-5
     2.4.4  Selected Remedy:  Other Plumes	2-5
2.5   STATUTORY DETERMINATIONS	2-6
2.6   SIGNATURES FOR LEAD AND SUPPORT AGENCIES	2-6

3.0   DECISION SUMMARY	3-1
3.1   SITE NAME, LOCATION AND DESCRIPTION	3-1
     3.1.1  Site Name and Location	3-1
     3.1.2  Land and Water Use	3-1
     3.1.3  Regional Topography	3-1
     3.1.4  Geology/Hydrology	3-2
3.2   SITE HISTORY AND ENFORCEMENT ACTF/mES	3-6
3.3   HIGHLIGHTS OF COMMUNITY INVOLVEMENT	3-9
3.4   SCOPE AND ROLE COMPREHENSIVE BASEWIDE-PART 1	3-10
3.5   NATURE AND EXTENT OF GROUNDWATER CONTAMINATION	3-11
     3.5.1  Shallow Hydrostratigrapic Zone (HSZ)	3-12
     3.5.2  Upper Subshallow HSZ	3-13
     3.5.3  Lower Subshallow HSZ	3-13
     3.5.4  Confined HSZ	3-13
     3.5.5  Deep HSZ	3-14
3.6   SUMMARY OF GROUNDWATER PLUME RISKS	3-14
     3.6.1  Human Health Risk Assessment	3-14
     3.6.2  Ecological Risk Assessment (ERA)	3-23
     3.6.3  Screening of Contaminants and Groundwater Plume Regions	3-23
3.7   DESCRIPTION OF THE ALTERNATIVES	3-29
     3.7.1  Alternative 1 No Action	3-31

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31 January 1997

      3.7.2  Alternative 2 Impacted Area Weil-Head Treatment/Well Destruction
            and Monitor	3-32
      3.7.3  Alternative 3 Extraction with TCE Capture Objective of 5 ug/L	3-34
      3.7.4  Alternative 4 Extraction with TCE Capture Objective of 0.5 ng/L	3-37
      3.7.5  Alternative 5 Extraction with TCE Capture Objective of 3 ug/L	3-39
      3.7.6  Alternative 6 Extraction for Plume Control Combined with Potential
            Well-Head Treatment	3-41
3.8    DETAILED AND COMPARATIVE ANALYSES OF REMEDIAL
      ALTERNATIVES	3-43
      3.8.1  Main Base Plume Regions	3-45
      3.8.2  East Base Plume Region	3-50
      3.8.3  Summary of Analysis and Selected Remedy	3-54
3.9    STATUTORY DETERMINATIONS	3-61
      3.9.1  Main Base Plume	3-61
      3.9.2  East Base Plume	3-62

4.0    LIST OF APPLICABLE OR RELEVANT AND APPROPRIATE
      REQUIREMENTS (ARARs) AND TO-BE-CONSIDEREDS (TBCs)...	4-1
4.1    CHEMICAL-SPECIFIC ARAR AND TBCs	4-2
      4.1.1  Federal Chemical-Specific ARAR and TBCs	4-2
      4.1.2  State Chemical-Specific ARAR and TBCs	4-2
4.2    LOCATION-SPECIFIC ARAR AND TBCs	4-3
      4.2.1  Federal Location-Specific ARAR	4-3
      4.2.2  State Location-Specific ARAR	4-4
4.3    ACTION-SPECIFIC ARAR AND TBCs	4-4
      4.3.1  Federal ARAR	4-4
      4.3.2  State ARAR and TBCs	4-4

5.0    RESPONSIVENESS SUMMARY	Tab 5

APPENDIX A:  ADMINISTRATIVE RECORD^INDEX	Tab 6

TABLES	.'.	Tab 7

FIGURES	Tab8

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                  Reference List for Castle Air Force Base
            Comprehensive Basewide-Part 1 Record of Decision

 1.  Castle Air Force Base Draft Comprehensive Basewide Groundwater Remedial
 Investigation/ Feasibility Study - Part 1, Jacobs Engineering Group Inc., December 21,
 1995.

 2.  Castle Air Force Base Final Comprehensive Basewide Groundwater Remedial
 Investigation/ Feasibility Study - Part 1, Jacobs Engineering Group Inc., June 12, 1996.

 3.  Interim Record of Decision, Operable Unit No. 1, Castle Air Force Base, Merced
 County, California, August 7, 1991.

 4.  Record of Decision, Operable Unit No. 2, Castle Air Force Base, Merced County,
 California, November 1993.

 5.  Interim Guidance on Preparing Superfund Decision Documents: The Proposed Plan,
 the Record of Decision, the Explanation of Significant Difference, the Record of Decision
 Amendment, U.S. Environmental Protection Agency, Office of Emergency and Remedial
 Response, EPA/540/G-007, July 1989.

 6.  The Water Quality Control Plan (Basin Plan) for the California Regional Water Quality
 Control Board Central Valley Region, The Sacramento River Basin and the San Joaquin
 River Basin, Third Edition, 1994.

 7.  Castle Air Force Base Long Term Groundwater Sampling Plan, Jacobs Engineering
 Group Inc., January 1996.

 8.  Draft Revised Design Basis Report for Castle Airport, Jacobs Engineering Group Inc.,
 January 1996.

 9.  Final Revised Design Basis Report for Castle Airport, Jacobs Engineering Group Inc.,
 August 1996.

 10. Castle Air Force Base Comprehensive Basewide Program - Part 1: The Proposed
Plan for Remedial Action of Groundwater, Booz, Allen & Hamilton Inc., June 1996.

 11. United States Air Force Installation Restoration Program Castle Air Force Base
Community Relations Plan, Gutierrez-Palmenberg Inc., May  1995.

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                                                                  31 January 1997
                     FINAL RECORD OF DECISION

                        CASTLE AIR FORCE BASE

          COMPREHENSIVE BASEWIDE PROGRAM-PART 1
1.0      INTRODUCTION

This decision document presents the remedial actions (RAs) selected for the comprehensive
cleanup of groundwater at the formerly active Castle Air Force Base (AFB), Merced County,
California. The RAs under this Comprehensive Basewide Program-Part 1 (CB-Part 1) are
being carried out to complete the cleanup of all groundwater plumes at Castle AFB as the
first of a two part process leading to the final comprehensive cleanup of all soil and
groundwater contamination at the site (CB-Part 2).

The selected RAs for CB-Part 1 were developed in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended
by the Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
These decisions, documented herein, are based on the information contained in the
Administrative Record File for Castle AFB. The Administrative Record Index (Appendix A)
identifies documents that were considered or relied upon to make these decisions.

The purpose of this Record of Decision (ROD) is to decide the appropriate level of
groundwater remediation necessary to protect human health and the environment, and to
determine what requirements are applicable or relevant and appropriate requirements
(ARARs) based on the groundwater beneficial use designation and site-specific conditions.

This ROD has been divided into five sections to address the selected RAs for groundwater
remediation at Castle AFB. These five sections are:

Section 1.0 Introduction. This section serves as an overall introduction to the ROD.

Section 2.0 Declaration For The Record of Decision. This section documents the RAs
selected for groundwater cleanup at Castle AFB and serves as an abstract for the key
information contained in the ROD. It provides signatures of concurrence by the U.S. Air
Force (AF), the U.S. Environmental Protection Agency (EPA), and the State of California
Environmental Protection Agency (Cal/EPA).
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31 January 1997

Section 3.0 Decision Summary. This section provides an overview of the site
characteristics, the alternatives evaluated, and the analysis of those options. It also identifies
the selected remedy and explains how the remedy fulfills statutory requirements.

Section 4.0 Listing of Applicable or Relevant and Appropriate Requirements (ARARs)
and To-Be-Considereds (TBCs). This section describes the Federal and State ARARs
required to be complied with under this ROD.

Section 5.0 Responsiveness Summary. This section contains a summary of comments
received during the public comment period and responses to those comments. In addition, a
summary of agency comments on the Preliminary Draft and Draft Final ROD, and responses
to these comments, are included. The Responsiveness Summary can be found at Tab 5.

Appendix A provides the Administrative Record Index and can be found at Tab 6. Figures
and tables referenced in the ROD can be found at Tabs 7 and 8, respectively.
                            FINAL RECORD OF DECISION
         CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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2.0   DECLARATION FOR THE RECORD OF DECISION
This section documents the RAs selected for groundwater cleanup at Castle AFB and serves
as an abstract for the key information contained in the ROD. It provides signatures of
concurrence by the AF, the EPA, and the Cal/EPA.

For the groundwater plumes selected for RAs under CB-Part 1, the following determinations
are in effect:

•  Statutory Preference for Treatment as a Principal Element is Met and a Five-Year Review
   is Required for the Main Base and Castle Vista Plumes.

•  Statutory Preference for Treatment as a Principal Element is Not Met and a Five-Year
   Review is Required for the East Base Plume.

2.1    SITE NAME AND LOCATION

Castle AFB (currently known as Castle Airport) is a National Priorities List (NPL) Site
located in Merced County, California.

2.2    STATEMENT OF BASIS AND PURPOSE

This ROD presents and documents the RAs selected for the cleanup of groundwater at Castle
AFB. CB-Part 1 is intended to address the full range of contaminated groundwater under
both the Castle AFB site and the contiguous areas where contaminated groundwater has
migrated off base.

The objective of the Castle AFB CB-Part 1 RAs is to capture the contaminated groundwater
plume(s) within the Maximum Contaminant Level (MCL) boundary of the most restrictive
contaminant present, and clean up the contaminated groundwater to MCL levels. This ROD
supersedes previous groundwater RODs (i.e., the Operable Unit (OU) 1 Interim ROD and the
OU 2 ROD), and the ongoing and planned actions under these two prior RODs are integrated
into the selected remedy for the comprehensive cleanup of Castle AFB groundwater
contamination.

These RAs were chosen in accordance with the CERCLA, as amended by the SARA (42
U.S.C. Section 9601 etseg.,) and, to the extent practicable, the NCP (40 Code of Federal
Regulations (CFR) Part 300). The Castle AFB CB-Part 1 ROD is based on information
contained in the Administrative Record.  An Administrative Record Index (Attachment A)
identifies the documents upon which the decision is based. The Cal/EPA and the EPA
concur on the selected remedy.
                            FINAL RECORD OF DECISION
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2.3     ASSESSMENT OF THE SITE

The contamination of groundwater at Castle AFB was investigated under the Castle AFB
Installation Restoration Program (IRP) and is described and evaluated in the CB-Part 1
Remedial Investigation/Feasibility Study (RI/FS). As a result of past AF operations
conducted between 1941 and 1995, groundwater contamination exists at Castle AFB.
Contamination affects groundwater beneath the base and extends to off-base areas in the
immediate vicinity of the base. The main sources of contamination include industrial
activities, equipment maintenance, landfill disposal, and fuels storage and delivery.

The IRP at Castle AFB resulted in the identification and characterization of numerous
potential sources of groundwater contamination, and the division of the contaminated areas
into three OUs. Two of these OUs, OU 1 and OU 2, were location-specific areas
representing groundwater contamination, and the third OU, known as the Source Control
Operable Unit (SCOU) was defined to address soil contamination at a wide variety of
locations.

The CB program was subsequently defined to provide a comprehensive approach to
groundwater and soil cleanup, with the CB-Part 1 dealing with all groundwater
contamination at Castle AFB. Under CB-Part 1, seven plume regions were identified and
evaluated in the CB-Part 1 RI/FS. Two of these (Main Plume Regions 1 and 2) correspond
to the OU 1 and OU 2 areas, and are collectively referred to as the Main Base Plume. The
other plume regions evaluated are East Base Plume, Castle Vista Plume, North Base Plume,
Landfill 1 Plume, and Landfill 4 Plume.

Although groundwater cleanup actions are underway  at Castle AFB in the OU 1 and OU 2
areas, there are additional areas of groundwater contamination that are not currently being
addressed under these OUs. Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response adtions selected in this ROD, may present
a current or potential threat to public health, welfare or the environment.

2.4     DESCRIPTION OF THE REMEDY

The CB-Part 1 RI/FS considered all groundwater contamination plumes at Castle AFB and
performed detailed analyses of potential  remedial options to clean up elevated levels of
Trichloroethylene (TCE) and other contaminants for two of the plumes. The two plumes
evaluated in detail are the Main Base Plume and the East Base Plume.  In addition, further
action was recommended in the RI/FS for the Castle Vista Landfill Plume, although detailed
analyses were not carried out. Table 2-1 provides a summary of the remediation decisions for
groundwater plumes at Castle AFB.

The Main Base Plume regions contain most of the TCE present in the groundwater beneath
Castle AFB. The bulk of the contamination will be captured by a currently-operating system

                             FINAL RECORD OF DECISION
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                                                                     31 January 1997

(OU 1), a system that is scheduled to begin operating in 1996 (OU 2), and planned
enhancements and expansion of the OU 1 system. A pump and treat approach, building on
the existing and planned OU 1 and OU 2 systems, was recommended in the RI/FS and is the
selected remedy for the Main Base Plume.

The East Base Plume consists of a TCE-plume region associated with a source known as Fire
Training Area 1 (FTA-1), and an isolated area of contamination east of the main runway that
may be associated with the Main Base Plume. The remedy for the East Base Plume is the
sealing and abandonment of wells to protect against further cross contamination of
groundwater zones and monitoring to develop a more complete definition of the plume.  The
need for future active remediation (i.e., pump and treat) will be determined through an annual
reevaluation of the monitoring information, in accordance with trigger language established
in this ROD.

The Castle Vista Plume was not identified in the RI/FS for RA, but has been included for
active remediation because of additional data from data gap wells. This data indicates that
groundwater contamination exceeds MCLs and presents a greater extent of contamination
than was previously evaluated in the RI/FS. Because of this new information, an active pump
and treat remedy, similar to that of the Main Base Plume, has been selected as a presumptive
remedy for this plume.

No further active remediation is planned for the other remaining plume areas.

2.4.1  Selected Remedy: Main Base Plume. The selected remedy for the Main Base
Plume consists of plume capture and treatment to achieve groundwater cleanup to the MCL,
implemented with a phased approach; this remedy includes and integrates the ongoing and
planned remedial activities authorized in the OU 1 Interim ROD and the OU 2 Final ROD.
The phased approach was chosen in order to collect technical information from operation of
OU 1 and OU 2 systems and the Long-Term Groundwater Sampling Program (LTGSP). This
information will be used as input to the evaluation of technical and economic factors
associated with the design of subsequent system expansion.

The selected remedy for the Main Base Plume consists of the following three sequential
phases of pump and treat groundwater remediation:

Phase 1:  The first phase takes advantage of existing OU 1  treatment capacity, to expand the
treatment of groundwater in the OU 1 area to remove TCE and control migration of TCE "hot
spots" in the shallow hydrostratigraphic zone (HSZ) of OU 1. This is being accomplished by
expanding the OU 1  extraction system through installation of new extraction wells in the
shallow HSZ. Granular Activated Carbon (GAC) and/or air stripping groundwater treatment
systems will be utilized to achieve treated water release levels identified in Table 4-3 of this
ROD. Design of the OU 1 expansion is included in the ongoing effort known as the Revised
                             FINAL RECORD OF DECISION
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31 January 1997

Basis of Design Report (RBDR). In addition, the OU 2 groundwater extraction network will
be completed and operations initiated.

Phase 2: Phase 2 will enhance the OU 1 extraction network to a multiple HSZ groundwater
remediation system with the addition of extraction wells and the utilization of GAC or air
stripper treatment systems to achieve effluent release levels stipulated in this ROD (see Table
4-3 at Tab 5). A water reuse study will be conducted to determine the most appropriate
combination of reinjection, canal discharge, and water reuse to be utilized for the disposal of
treated groundwater. Pump tests will be conducted to obtain necessary hydrologic
information on HSZ properties.

Phase 3: Data collected from the first two phases will be evaluated and a Phase 3 Technical
Evaluation and Design Study will be prepared to determine what additional wells will be
needed to achieve the overall cleanup objectives. By the onset of Phase 3, both Phase 1 and 2
pump and treat systems will have been installed, data gap wells and the LTGSP network will
be in place, pump tests will have been evaluated, and the flow and transport models will have
been updated. That information will facilitate better predictions of the hydraulic control of
the HSZs and plume remediation time periods, and will provide the basis for design decisions
regarding Phase 3 expansion of the groundwater remediation system.  The Phase 3 Technical
Evaluation and Design Study is scheduled for completion in draft form in August 1998, with
finalization in January 1999. Construction on the Phase 3 groundwater system expansion is
scheduled to begin in  January 1999, with completion in October 1999.

The selected remedy is expected to cost-effectively remove TCE and other contaminants in
the Castle AFB groundwater to the MCL cleanup objective and prevent further plume
migration.  Based on the concepts evaluated in the CB-Part 1 FS, the preliminary range of the
estimated present worth costs of the selected remedy (not including OU 1 and OU 2 costs) is
from $15.7 million to $33.4 million over a period of 15 years.

The three phases of groundwater remediation will be fully defined during remedial design
(RD) and RA stages.  Based on current information, the selected remedy will address the
principal threat of hazardous material groundwater contamination. TCE in the groundwater
at Castle AFB will be removed to or below 5 micrograms per liter.

2.4.2  Selected Remedy: East Base Plume. To achieve the overall objective for cleanup
of groundwater at Castle AFB, the selected remedy for the East Base Plume (Impacted Area
Well Destruction and Monitoring) utilizes the sealing and abandonment of wells to protect
against further cross contamination of HSZs in the East Base Plume area, and monitoring to
develop a more complete definition of the contamination.  If further active remediation is
needed, appropriate RA will be implemented based on the conditions that trigger the need for
remediation; in particular, a pump and treat approach will be implemented as the presumptive
remedy for further cleanup action. The need for and design of this additional action will be
determined through an annual revaluation of monitoring information. The criteria defining

                              FINAL RECORD OF DECISION
          CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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                                                                       31 January 1997

the need for future pump and treat RA (i.e., the trigger conditions) are specified in Section 3 of
this ROD.

The estimated present worth cost of the Impacted Area Well Destruction and Monitoring
alternative for the East Base Plume, exclusive of additional action under the presumptive
remedy, is $0.5 million.  Additional active remedial measures have not been estimated, but
would be significantly greater than this value.

2.4.3 Selected Remedy: Castle Vista Plume. Although detailed analysis was not conducted
for the Castle Vista Plume, it was recognized in the RI/FS that the Castle Vista Plume had not
been fully characterized. Additional data collection is continuing in this plume area, and
analysis of the data collected to date indicates that active groundwater remediation in this area is
necessary. A presumptive remedy of pump and treat, similar to the remedy selected for the Main
Base Plume, will be used to meet the groundwater clean up requirements of the Castle Vista
Plume. The present remedy, established in this ROD, consists of capturing the contaminant
plume and remediating the groundwater to MCL levels.  For the Castle Vista Plume, further
analysis will be conducted to determine the appropriate cleanup level, consistent with Section
IIIG of SWRCB Resolution 92-49. This evaluation will be carried out as part of the RD/RA
activities. For reasons of operational and reporting convenience and efficiency, this additional
RA will be integrated  into the phase approach of the CB-Part I RD/RA, described under the
remedy for the Main Base Plume.

2.4.4 Selected Remedy: Other Plumes.  The AF, with the concurrence of the EPA and
Cal/EPA, has determined that active remediation of the North Base, Landfill I, and Landfill 4
Plumes is not warranted at this time because action is being taken to remediate the sources, and
because removing the  low concentration contaminants from the groundwater would provide little
benefit while incurring high costs.  However, because several of the contaminants are above
primary drinking water standards, institutional controls will be implemented to prevent the
installation of groundwater supply wells on Castle AFB that would jeopardize public health or
the environment from  North Base, Landfill 1  and Landfill 4 Plumes.  Additionally, long-term
monitoring will be performed under the LTGSP to monitor contaminant concentrations in these
plume areas. Contaminant concentration levels in the groundwater will be reevaiuated annually.
If the contaminant concentrations drop below the MCL and beneficial use concentrations for one
year, any institutional  controls may be removed. If, at any time, monitoring or modeling
indicates that the contaminants will not meet the MCL and beneficial use concentrations within a
reasonable time, or at  least forty years from the date of the ROD,  or that significant migration of
the contaminants may occur at levels above MCL and beneficial use concentrations which
impact public health or the environment, active remediation will be considered.
                           FINAL RECORDS OF DECISION
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  31 January 1997
  2.5  STATUTORY DETERMINATIONS

  The selected remedy is protective of human health and the environment, complies with federal
  and state requirements that are legally applicable or relevant and appropriate for the RAs, and is
  cost-effective. This remedy utilizes permanent solutions and alternative treatment technologies
  to the maximum extent practicable and satisfies the statutory preference for remedies that
  employ treatment that reduces toxicity, mobility, or volume as a principal element.
  2.6  SIGNATURES FOR LEAD AND SUPPORT AGENCIES
 QflL
  Albert F. Lowas, JR.^/
  Acting Director
  Air Force Base Conversion Agency
Dan Opalski
Chief, Federal Facilities Cleanup Branch
Region IX
U.S. Environmental Protection Agency
i
Anthony J. I^nflis, P.E."
Chief, Northern California Operations
Office of Military Facilities
Department of Toxic Substances Control
California Environmental Protection Agency
    Date
 State signature indicates concurrence with the selected remedy
                             FINAL RECORD OF DECISION
         CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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3.0  DECISION SUMMARY
This decision summary provides an overview of the environmental concerns posed by
groundwater plume regions at Castle AFB and the remedies selected to address them. It
includes a description of the site characteristics and the remedial alternatives considered in
the Castle AFB CB-Part 1 RI/FS.  It summarizes the analysis of these alternatives when
compared to criteria set forth in the NCP.  This Decision Summary explains the rationale for
the remedy selections for the Main Base, East Base, and Castle Vista Plumes, and how the
selected remedies satisfy the statutory requirements of CERCLA.

3.1    SITE NAME, LOCATION AND DESCRIPTION

3.1.1 Site Name and Location. Castle AFB (currently referred to as Castle Airport) is
located in Merced County, California (Figure 3-1). The site covers an area of 2,777 acres,
and is comprised of a runway and  airfield, industrial areas, housing, recreational facilities,
and several noncontiguous parcels.

3.1.2 Land and Water Use.  Land use within a two-mile radius of Castle AFB is primarily
agricultural,  with the exception of residential areas in the community of Atwater.  Crops
grown in the area consist mostly of almonds, peaches, and grapes. Several small dairies and
a large chicken farm are located to the east.  Open pasture lands are located to the north and
east. Residential areas are located primarily west of Castle AFB and include former base
housing, trailer parks, recently constructed residential suburban housing, and rural farm
residences. Land use along Wallace Road is mixed residential and agricultural (i.e.,
orchards). Land use on the airport currently includes a mixture of industrial and light-
industrial facilities and offices. Potential future land uses at Castle AFB include schools,  as
well as residential and recreational uses.
      Regional Topography. Castle AFB is located in the east central part of the San
Joaquin Valley. Neighboring communities include Atwater, located to the immediate west;
Winton, located to the north-west; and Merced which is approximately five miles to the east
south-east of Castle AFB.

The San Joaquin Valley forms the southern half of the Great Valley Geomorphic Province of
California. This province is approximately 400 miles long and averages about 40 miles in
width. It is bounded by the Sierra Nevada Mountain Range to the east, the Coastal Mountain
Range to the west, and is drained by the San Joaquin River. This river flows from the
southeast to the Sacramento-San Joaquin Delta region, which lies between the Central Valley
and the San  Francisco Bay.

Castle AFB  is located about halfway between the Merced River and Black Rascal Creek, two
southwest-flowing tributaries of the San Joaquin River. The valley floor in the vicinity of the
airport area  slopes gently to the west-southwest Natural drainage is to the southwest;

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31 January 1997

however, surface flow patterns are locally controlled by a system of drainage and irrigation
canals.

The total difference in elevation across Castle AFB is approximately 35 feet, ranging from
200 feet above mean sea level (MSL) at the northwestern comer to 165 feet above MSL at
the southern corner.

3.1.4  Geology/Hydrology. A description of the geologic setting, surface water conditions,
HSZs, groundwater flow conditions, and groundwater usage which comprise the conceptual
hydrogeologic model for Castle AFB is presented in this section.

3.1.4.1 Geology. The eastern San Joaquin Valley of Central California is underlain by a
basement complex composed of metamorphic and granitic rocks. In the vicinity of Castle
AFB, the basement is overlain by a thick sequence of sedimentary deposits of
Tertiary/Quaternary age (Figure 3-2).

Consolidated sedimentary units overlie the basement complex and have a minimum
combined thickness of over 700 feet. These consolidated units include, from oldest to
youngest, the lone, Valley Springs, and Mehrten Formations.

Unconsolidated sediments overlie these formations from an elevation of approximately 450
feet below MSL to an elevation of 165 feet above MSL. Beneath Castle AFB, the
unconsolidated units include the Laguna, Turlock Lake, Riverbank, and Modesto Formations.
Recent surficial dune deposits, which attain a maximum thickness of approximately 10 feet,
have occurred at the ground surface.

Castle AFB is located on an old Merced River flood plain that has been exposed and leveled
by progressive down-cutting of the Merced River and its tributaries and by wind erosion.
Quaternary-age sediments extend from the ground surface to about 350 feet below ground
surface (bgs).  The upper 20 feet of these deposits consist of eolian and flood plain sediments
of Holocene age.  The transition from Holocene age to Pleistocene age occurs at the base of
the eolian and flood plain sediments.             	

3.1.4.2 Nature and Occurrence of Groundwater. The migration and fate of dissolved
contaminants in groundwater at Castle AFB depends largely on natural hydrogeologic
conditions and pumping influences due to use of groundwater as a resource. The site-wide
conceptual model is presented schematically as Figure 3-2. The figure depicts major water-
bearing zones, contaminant sources, migration pathways, and potential receptors of
contaminated groundwater on and near Castle AFB.

The Merced River and Black Rascal Creek, two tributaries of the San Joaquin River, are the
major surface drainages near Castle AFB. Regional surface drainage is to the southwest, but
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is substantially altered by a network of agricultural drains and canals. These drains and
canals include Canal Creek near the eastern boundary of Castle AFB, Escaladian Canal in the
north, and Livingston Canal in the southwest.

Drainage on Castle AFB is controlled through a system of storm drains and open channels.
Runoff is diverted to the southern tip of the site where the water accumulates behind a weir.
Except for periods of prolonged or heavy rain, runoff does not discharge from Castle AFB.
Water collected behind the weir dissipates by evaporation and percolation. During heavy
rainfall, water overflows the weir and discharges through  culverts to either Livingston Canal
or Canal Creek.

3.1.4.3  Hydrostratigraphic Zones. The sedimentary deposits in the upper 600 feet beneath
Castle AFB are heterogeneous. Most sediments appear deposited in a fluvial system, though
eolian and alluvial deposits are not uncommon. These sediments are typically deposited
through an aggradational system of cutting and filling. This type of system is characterized
by laterally discontinuous lenses of channel-fill sands and gravels surrounded by less
permeable overbank deposits.

Prior to the CB-Part 1 RI/FS, the stratigraphy beneath the site was thought to be divided into
three general water-bearing zones: the shallow, subshallow, and confined. Based on the
results of the CB-Part 1 RI/FS, the stratigraphy was redefined into five HSZs: the shallow
HSZ, upper subshallow HSZ, lower subshallow HSZ, confined HSZ, and deep HSZ, as
shown on Figure 3-2.

Hydraulically isolated stratigraphic zones or aquifers are not generally found beneath Castle
AFB because of the complex fluvial/alluvial stratigraphy  dominated by localized stream
channel deposits.  Each HSZ is a sequence of sediments with the finer sediments generally
occurring at the top and the predominant water-bearing sections or lenses at the bottom. The
HSZs do not represent isolated aquifers, but provide the general stratigraphic correlation
(which can often be recognized during drilling) to guide the installation of monitoring wells
within correlative predominant water-bearing units. Significant vertical hydraulic connection
between HSZs is postulated to exist at certain locations.

The relatively high permeability coarse grained sands and gravels which generally occur near
the base of each HSZ make up the predominant water-bearing sections (PWBS) of the HSZs,
have little or no fines, and have been classified using the Unified Soil Classification System
(USCS) as GW or GP (clean gravels) and SW or SP (clean sands).

A brief description of each of the HSZs is presented in the following paragraphs:

Shallow Hydrostratigraphic Zone. The shallow HSZ extends from the water table
(typically 60 to 80 feet bgs) to the top of a clay layer at approximately 95 feet bgs. The
PWBS of the shallow HSZ is composed of fluvial deposits of sand and gravel which trend in

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a northwest to southeast direction. To the southwest the sands and gravels "pinch out"
transitioning to finer grained, less permeable deposits.

Upper Subshallow Hydrostratigraphic Zone.  The upper subshallow HSZ occurs at about
95 to 160 feet bgs and is stratigraphically equivalent to the upper portions of the Turlock
Lake Formation (Jacobs, 1995a). At Castle AFB, the upper subshallow HSZ is
heterogeneous both laterally and vertically, consisting mostly of fine-grained flood plain
deposits with medium-grained channel sands to the south of the airport. Upper subshallow
HSZ sands are lenticular and intermittent, but appear to broaden, thicken and grade into the
channel sands to the south of Castle AFB. These sand units comprise what is considered the
PWBS for the upper subshallow HSZ and appear to trend in a northwest to southeast
direction as in the shallow HSZ.

Lower Subshallow Hydrostratigraphic Zone.  The lower subshallow HSZ occurs from
about 160 to 220 feet bgs,  and is stratigraphically equivalent to the middle portions of the
Turlock Lake Formation (Jacobs, 1995a). This HSZ consists of laterally semi-continuous
segments of interbedded fine-grained sands, silts and clays between  160 and 180 feet bgs. It
contains more gravel and coarse-grained sands between 180 and 220 feet bgs.  The
sand/gravel units of the lower subshallow HSZ also trend northwest to southeast.

Confined Hydrostratigraphic Zone. The confined HSZ occurs from approximately 220 to
350 feet bgs. It contains thicker, more continuous zones of water-bearing sands than the
upper and lower subshallow HSZs. Most of the older Castle AFB production wells on site
produce from the confined HSZ. The lower part of the confined HSZ consists of the North
Merced Gravel (Jacobs, 1995a) which is the PWBS of the confined HSZ. The name
"confined" was used by previous investigators at Castle AFB. The HSZ as a whole is not
confined; however, the North Merced Gravel at the base of the confined HSZ is hydraulically
confined locally and trends in a north to south direction.

Deep Hydrostratigraphic Zone. The top of the deep HSZ is approximately 350 feet bgs.
Its vertical extent is not known.  The deep HSZ is an important water source in the San
Joaquin Valley (Weston, 1988). The PWBS of the deep HSZ occurs in the Laguna
Formation, about 510 feet bgs and extends into the upper part of the Mehrten Formation at
about 650 feet bgs (Jacobs, 1995a). The Laguna Formation consists of a poorly consolidated
mixture of clay, silt, sand, and conglomerate, while the Mehrten Formation is mainly a
mixture of consolidated claystone, sandstone, siltstone, and conglomerate.

3.1.4.4 Groundwater Flow Direction and Movement The general horizontal groundwater
flow direction beneath Castle AFB is west-southwest toward the San Joaquin River. This is
consistent with  the regional groundwater flow hi the eastern part of the San  Joaquin Valley.
Two regional pumping centers, located to the northwest and south-southwest of Castle AFB
influence local groundwater flow directions in the Atwater-Merced area.
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3.1.4.5 Description of Horizontal and Vertical Gradients.  Groundwater elevations have
been determined from data collected during the fourth quarter sampling event in November
1995. Based on calculations from this data, the horizontal gradient for the shallow, upper
subshallow, and lower subshallow HSZs is generally 0.001 feet/foot (ft/ft).

There is a small, natural vertical component of groundwater flow beneath Castle AFB
(Jacobs, 1995a). Hydrographs indicate that there is a relatively consistent downward vertical
gradient between the shallow and upper subshallow HSZs and that these two HSZs are in
relatively close hydraulic connection.

Hydrographs also indicate that there is essentially no difference in water elevation between
the lower subshallow and shallow HSZs, except during the third or fourth quarters of 1995,
when water levels in the lower subshallow HSZ dropped, creating a downward gradient.

The cyclic seasonal pattern observed in elevations in the confined HSZ is due to the pumping
of large volumes of groundwater for irrigation purposes during the late summer and fall. The
dissimilarity in water level fluctuations between the shallow and confined HSZs suggests
there is little direct hydraulic connection between these zones.

3.1.4.6 Groundwater Usage. Castle AFB, the City of Atwater, and the Merced Irrigation
District are three principal groundwater utilizing entities on or near Castle AFB. In addition
to on-site production wells, there are more than 100 municipal, domestic, irrigation, and
production wells within one mile of Castle AFB.  The deepest well (City of Atwater well,
AM 19, grid Q,3) is completed to 670 feet bgs while the shallowest wells are completed to
less than 100 feet bgs."Total groundwater pumping in the Atwater-Merced area ranged from
about 47,000 to 120,000 acres-feet per year during the 10-year period between 1963 and 1973
(Jacobs, 1996).

In 1988, 11 wells belonging to the City of Atwater were in service and produced about 6,300
acre-feet of water (see Figure 3-3).  AM-16 near Castle AFB is considered a prime potential
conduit/receptor. Well AM-16 is screened from 330 to 600 feet bgs within the confined and
deep HSZs. The well is located about 1,700 feet  west (downgradient) of the estimated
boundary of the TCE plume in the confined HSZ. Well AM-16 has a pumping capacity of
approximately 2,000 gallons per minute (gpm) and produces an average  monthly volume of
approximately 70 million gallons. The significant groundwater drawdown observed in the
confined HSZ in the southwest portion of the site is in part due to pumping from AM-16.

Castle AFB operates on base groundwater production wells. The production wells are
capable of producing 4,900 gpm. Based on data from the past year (when the base was still
open), summer usage is approximately 2,000 gpm, while winter usage is approximately 1,000
gpm. Currently, water usage is much less. The principal groundwater wells at the site are
PW-10, andPW-12. They extract groundwater from the confined and deep HSZs. The only
other active production wells at Castle AFB are PW-6 and PW-11.

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3.2    SITE HISTORY AND ENFORCEMENT ACTIVITIES

Castle AFB was first used as a military air base in December 1941. The primary mission of
the base through World War n was the training of Army air crews. The Strategic Air
Command (SAC) assumed responsibility of the base in 1946 and occupied the base with the
93rd Bombardment Wing until the base closed in September 1995. Fuels (JP-4), solvents
(TCE), and chemicals were handled at the base since the 1940s. Municipal and chemical
wastes were also generated as a result of maintenance operations, fuel management, fire
training, and other base activities. In the 1950s, expanded industrial activities related to the
SAC mission resulted in increased waste generation rates.

Originally, the major industrial activities related to aircraft maintenance centered in two
hangers (Buildings 47 and 51) and the machine shop (Building 52, later demolished in 1977),
located on the southwestern side of Apron Avenue. In 1955, an additional parking apron,
hanger (Building 1550), and other structures were added to support the newly arrived 456th
Fighter Interceptor Squadron. Since 1955, Building 1550 has been used extensively for
industrial activities. Buildings 1253 and 1260 were built in the late 1970s and assumed the
majority of the industrial activities previously performed in Building 52.  These activities
included metal plating and processing, and jet engine maintenance.

In 1978, following the sampling of several water production wells, the AF determined that
the groundwater beneath Castle AFB was contaminated with TCE and other volatile organics.
During the routine sampling of several base and private wells in 1980, trace levels of TCE
were detected in the four base water production wells.  Seven test wells were then installed in
the shallow aquifer by the base as part of the investigation. The results of this sampling
program prompted the base to construct a new deep aquifer water supply well (PW-10) and
provided the impetus for the AF's aggressive strategy to address the problem of groundwater
contamination under the IRP at Castle AFB. This strategy included extensive investigations
leading to the initiation of groundwater cleanup actions at Castle AFB designed to control
migration of contaminated groundwater and to protect human health and the environment.

The initial phase of the IRP at Castle AFB was conducted in 1981, at which time 35 potential
contaminant source sites were identified. Follow-on activities confirmed and partially
delineated the extent of the TCE groundwater contamination. Seven previously unknown
potential source sites were also defined.

In March 1984, the California Regional Water Quality Control Board - Central Valley Region
issued Cleanup and Abatement Order Number 84-027.  This order required the base to
provide users of the base water supply and impacted off-base wells with potable water
supplies. Also, the base was required to implement remedial measures to correct identified
and future groundwater degradation from waste discharges.
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In September 1984, an additional field investigation was begun including the installation of
27 monitoring wells and 11 unsaturated zone lysimeters into the shallow aquifer to sample
for groundwater contamination and to test for perched water zones. This investigation
determined that the soils and sediments at the base had not been significantly impacted at the
majority of the sites investigated, but that the groundwater needed further evaluation. This
conclusion was considered preliminary and was evaluated in the RI/FS for the overall base.
Significant TCE concentrations were detected in the central or Main Base Sector. The final
report of this field investigation recommended additional investigations of the landfill, fire
training areas, fuel spills, and disposal areas, and for further evaluation of the TCE plume in
the Main Base Sector.

Results of the investigation and the base's groundwater sampling program indicated that TCE
contamination may be present not only in the Main Base Sector, but also in the South Base
Sector and Disposal Areas Nos. 2 and 4. As a result of these findings, further investigation
was conducted which included additional evaluations of the landfills, fuel spills and leaks,
and selected disposal  areas. These field investigations included soil organic vapor (SOV)
monitoring at 205 points, the drilling of 48 soil borings, the installation of 27 monitoring
wells and 5 lysimeters or perched wells, and conducting two rounds of groundwater
sampling.  These investigations were completed in April 1987, and the final report was issued
in August  1988.

Castle AFB fell under the provisions of CERCLA when amended in 1986.  Castle AFB was
proposed for the NPL of hazardous waste sites on July 22,1987. The base was officially
listed as an NPL site on November 21, 1989. The AF, the EPA, and the state signed an
interagency agreement, now known as the Castle AFB Federal Facility Agreement (FFA) on
July 21, 1989. The FFA is a legal document that outlines the basic CERCLA process
required of the AF, including CERCLA procedures to address  state requirements, and
documents the regulatory agency enforcement authority.

Results of all the above field investigations and data collection activities were used to
develop the initial RI/FS program. The first phase of RI field activities was initiated in
August 1988. These activities included the installation of 63 monitoring wells in the upper
and lower zone of the shallow aquifer and nine monitoring wells in the confined aquifer. In
June 1989, the second phase of the RI was initiated and included conducting two rounds of
quarterly groundwater sampling in 160 wells. These wells included previously installed base
and Phase U wells, new RI base wells, and off-base private wells.  In addition, 77 soil borings
were drilled and sampled to assist in the future characterization of various investigative sites.
Two rounds of groundwater level measurements were made, and 15 short-term (4-hour)
pump tests were also  conducted. The second phase of the RI field activities was completed in
February 1990. The results of the above field activities are described in the Preliminary Site
Characterization Report, which is the basis for the Interim OU 1 Interim ROD.
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The third phase of RI field activities began in March 1990 and continued through May 1991.
These activities included quarterly groundwater sampling, 30-day aquifer pump tests, a
preliminary site assessment of Castle Vista landfills, six water level snapshots, development
of Work Plan No. 2, quarterly groundwater samplings, water level snapshots, and a sewer line
TV camera survey.

During the third phase, Castle AFB was divided into two OUs, known as OU 1 and OU 2.
OU 1 and OU 2 are location-specific areas defined in an attempt by the AF to identify
groundwater contamination plumes and their related source areas. The geographical location
and area! extent of OU 1 and OU 2 are depicted in Figure 3-4. An Interim ROD for OU 1
was finalized in August of 1991 that addresses the principal Main Base TCE Plume
groundwater threat posed by TCE concentrations in the shallow HSZ beneath the central
portion of the Main Sector of the base and contiguous areas to the south and southwest of the
base. The selected remedy for the OU 1 Interim ROD involves 1) groundwater extraction
from a series of shallow wells, 2) surface treatment of the extracted groundwater by air
stripping, 3) reinjection of treated groundwater back to the shallow HSZ, 4) application of
natural biological enhancement to accelerate degradation of hazardous constituents and 5)
abating the air stripper emissions with granular activated charcoal. A Dispute Resolution
document for OU 1 and subsequent correspondence from the Regional Water Quality Control
Board provided the basis for the quantitative requirements for treatment of groundwater for
the OU.

A final ROD for  OU 2 addressing RAs for groundwater contamination in the Wallace Road
and DA-4 areas was signed in December 1994. The selected remedy in the OU 2 ROD
consisted of 1) design, construction, and operation of a groundwater extraction and treatment
system to treat extracted groundwater with air stripping technology, 2) discharge by
reinjection of treated groundwater to the same aquifer from which it was extracted, and 3)
groundwater monitoring to demonstrate that the extraction system is effectively capturing the
volatile organic compound (VOQ contaminant plume, attainment of cleanup standards
established for OU 2, and compliance with ARARs. Subsequently, the treatment technology
for OU 2 was changed to GAC treatment, documented in an Explanation of Significant
Difference (ESD).

The SCOU was separately identified to characterize soil (vadose zone) contamination, and
the LTGSP was established to monitor groundwater contamination. From a total of 209 sites
considered in the initial draft SCOU RI/FS, the soil at 38 sites or groups of sites was
identified as having the potential to affect the underlying groundwater quality. Additional
investigation work under the SCOU Action Plan is currently in progress, and an update to the
initial RI/FS is scheduled following completion of the Action Plan investigations.

In an attempt to control off-base migration of contaminated groundwater and to protect
human health and the environment, RD/RA (Phase IV) began in 1992 and is currently
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underway at OU 1 and OU 2. The CB Program was established to incorporate the final
evaluation and cleanup of both soil and groundwater. Because of an extension of the
investigation activities under the SCOU, the CB program was segmented into two parts. The
CB-Part 1 addresses groundwater contamination, one of the principal threats posed by the
site, and CB-Part 2 will be the final integration of all cleanup activities for soil and
groundwater at Castle AFB.

The CB-Part 1 RI/FS was conducted to extend the results of previous groundwater
investigations to address all groundwater plumes at Castle AFB. The objectives of the CB-
Part 1 RI/FS were 1) to investigate the nature and extent of groundwater contamination, 2) to
assess the risks which the groundwater contamination poses to human health and the
environment, 3) to evaluate the feasibility of various groundwater RA alternatives, and 4) to
recommend a preferred alternative.  The site-wide soil and groundwater cleanup decisions at
Castle AFB will be culminated with the final cleanup decisions of CB-Part 2.

3.3    HIGHLIGHTS OF COMMUNITY INVOLVEMENT

The Community Relations Plan (CRP) for Castle AFB was completed in  1990 and officially
updated in  1992 and again in May 1995 by Castle AFB's Office of Public Affairs, in
accordance with EPA guidance.  Consistent with the base's CRP, the AF established a
Restoration Advisory Board (RAB) composed of EPA, Cal/EPA, the AF, Merced County,
and local representatives from adjacent communities. The RAB meets on a quarterly basis to
provide the community representatives with up-to-date information on recent milestone
events.  Castle AFB publishes and distributes "Environmental Update," a community
newsletter, which serves to keep the community informed of recent activities.

The CB-Part 1 RI/FS and Proposed Plan were released to the public in June 1996. These two
documents were made available to the public in both the Administrative Record and an
information repository at the Merced Public Library.  The initial public comment period for
the Castle CB-Part 1 RI/FS and Proposed Plan was held between June 25, 1996 and July 25,
1996. This initial comment period was subsequently extended through August 25, 1996.
The public notice for the Proposed Plan was published in the Merced Sun on June 22, 1996
and July 12,1996; and in the Atwater Signal and the Livingston Chronicle on June 22, 1996
and July 17,1996.  In addition, public meetings were held on July 23, 1996 in which
representatives from the AF, Cal/EPA and the EPA participated to answer questions about
problems at the site and the remedial alternatives under consideration.

A response to the comments received during this period has been prepared as the
Responsiveness Summary, which is included as Section 5 of this ROD.  This decision
document presents the selected RA for the Castle CB-Part 1 in Merced, California chosen in
accordance with CERCLA, as amended by SARA and, to the extent practicable, the NCP.
The decision for this site is based on information contained in the Administrative Record.
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The public participation requirements of CERCLA Sections 113(K)(2)(B)(I-v) and 117 have
been met.

3.4   SCOPE AND ROLE COMPREHENSIVE BASEWIDE-PART1

The CB Program was originally established to combine final evaluation and cleanup of both
soil and groundwater at Castle AFB. Because of an extension of the investigation activities
under SCOU, the CB program was segmented into two parts. The CB-Part 1 addresses
groundwater contamination, one of the principal threats posed by the site, and CB-Part 2
addresses final integration and implementation of all cleanup activities for soil and
groundwater at Castle AFB.

The CB-Part 1 RI/FS was conducted to complete the groundwater investigations at Castle
AFB. The objectives of the CB-Part 1 RI/FS were 1) to investigate the nature and extent of
groundwater contamination, 2) to assess the risks which groundwater contamination poses to
human health and the environment, 3) to evaluate the feasibility of various groundwater RA
alternatives, and 4) to recommend a preferred alternative. The CB-Part 1 RI/FS incorporates
data through the second quarter of 1994 from the LTGSP; field investigations for OU 2; the
SCOU RI; and the CB-Part 1 groundwater investigation.  RAs under the SCOU and CB-Part
1 will be integrated with the final cleanup decisions of CB-Part 2.
                                                                 i
The CB-Part 1 ROD addresses basewide groundwater contamination, including all
groundwater plumes resulting from past activities at Castle AFB, both within the original
boundaries of Castle AFB and extending beyond the boundaries where off-site plume
migration has taken place.  Seven groundwater plume regions (representing six plumes, since
Main Base Plume Regions 1 and 2 are treated as a single plume) were identified and
evaluated as part of the CB-Part 1 RI/FS and remedies were recommended for three of these
plumes:  Main Base Plume; East Base Plume; and Castle Vista Plume.
                                           *••
The Main Base Plume, the East Base Plumes, and the Castle Vista Plume (Figure 3-5),
represent the principal groundwater contamination problems among the seven groundwater
contamination plume regions. TCE is the most significant contaminant at the Main Base and
East Base Plumes; other contaminants at the Main Base Plume include Benzene; Carbon
Tetrachloride; cis-l^-dichloroethene (cis-l,2-DCE); and Perchloroethylene (PCE). At the
East Base Plume, bis (2-ethylhexyl) phthalate (DEHP) is present in addition to TCE. The
major contaminants at the Castle Vista Plume are PCE and cis-1,2 DCE. Contaminants at the
North Base, Landfill 1 and Landfill 4 Plumes include TCE, DEHP, PCE and Antimony.

Remedial actions at OU 1 and OU 2 are being conducted to address the majority of the mass
of the Main Base Plume groundwater contamination. The intent of CB-Part 1 is to address
all groundwater contamination associated with Castle AFB, including the OU 1 and OU 2
areas as well as the other plumes not associated with the Main Base Plume.
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CB-Part 1 consolidates the groundwater cleanup activities at Castle AFB by expanding the
RAs currently underway at OU 1 and OU 2 to address the additional groundwater
contamination at the base. CB-Part 2 is planned to finalize and close out any remaining
issues associated with the cleanup of Castle AFB.

3.5    NATURE AND EXTENT OF GROUNDWATER CONTAMINATION

The principal Chemical of Concern (COC) in groundwater at Castle AFB is TCE. An
estimated 6,605 pounds of TCE is in the groundwater at Castle AFB. Other contaminants
detected at lower concentrations include benzene, toluene, ethylbenzene, and xylenes
(BTEX), petroleum hydrocarbons, inorganics, and other VOCs. Small areas of
contamination were detected at various locations throughout the base, but in general, were
very close to MCL or beneficial use criteria levels, and do not  pose significant risks. The
majority of the contamination significantly above MCL levels  is contained within the larger
TCE plumes and will be remediated by the remedy for the TCE plumes.

Groundwater contamination at Castle AFB has been divided into seven plume regions based
on geographic location and source of contamination (see Table 3-1). These regions are
defined as:  Main Base Plume  1, Main Base Plume 2, Landfill  4, North Base Plume, East
Base Plume, Landfill 1 Plume, and Castle Vista Plume.  Groundwater contamination is
limited to the shallow HSZ in all plume regions except for Main Base Plume Regions 1 and
2. Contamination is present in the shallow, upper subshallow, lower subshallow, and
confined HSZs within the Main Base Plume regions.

The largest extent of TCE contamination is within the Main Base Plume Regions 1 and 2
(Figure 3-6). They contain approximately 98 percent, by mass, of the TCE contamination
beneath Castle AFB. TCE is also present at the East Base, Castle Vista, North Base, Landfill
1, and Landfill 4 Plume regions. Volumes and contaminant masses are estimated for the
plumes containing TCE in Table 3-2a.

Three plumes in the East Base Plume Region are estimated to contain approximately 1.8
percent, by mass, of the TCE contamination beneath Castle AFB.  One of these plumes in the
East Base Region, the plume under Buildings 1762 and 1709, has been incorporated as part
of the Main Base Plume and will be addressed by the selected  remedy for the Main Base
Plume. The TCE plumes in the other five regions account for less than 0.2 percent of the
total TCE mass beneath the site. The lateral extent of the plumes and the TCE concentrations
generally decrease with increasing depth.  Contaminants have  not been detected in the deep
HSZ.

Plumes of organic contaminants of concern other than TCE have been identified in the
shallow HSZ within the Main Base, North Base and Castle Vista Plume regions and in the
shallow, upper subshallow and confined HSZs within the Main Base Plume regions. In
general, the extent of the other plumes are within the extent of the TCE Plume regions.

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Exceptions are DEHP in the North Base Plume regions in the shallow HSZ, and benzene in
the Main Plume Region 1 in the confined HSZ.  Volume and contaminant mass are estimated
for Groundwater Plumes of organic compounds identified in the CB-Part 1 RI (other than
TCE) in Table 3-2b.

Of the seven regions, three were considered for RA in the CB-Part 1 RI/FS (Main Base
Plume Region 1, Main Base Plume Region 2, and East Base Plume). However, Regions 1
and 2 of the Main Base Plume are considered a single plume resulting from two different
sources and the existing and planned remedial systems (OU 1 and OU 2) will capture
contaminants from both regions. The screening and selection of groundwater plumes for
consideration of RA is discussed in Section 3.6.3. In addition, although active remediation
was not planned for the Castle Vista Plume, additional data has been collected and a pump
and treat presumptive remedy is now planned for this plume.

Ongoing activities at Castle AFB include the monitoring of these plume regions (under the
LTGSP) and the investigation of identified data gaps.  Surface and near-surface sources of
groundwater contamination are being addressed under the SCOU.

As part of the CB-Part 1 Rl/FS, wells upgradient from Castle AFB were sampled and
evaluated to determine background concentrations of inorganic contaminants in groundwater
unaffected by historic Castle AFB actions, but potentially impacted by regional activities in
the San Joaquin Valley (agriculture, forestry, etc.).  This data was statistically analyzed to
determine a background level such that 95 percent of the naturally occurring inorganic
concentrations from non-AF operations would be below this value.  Some inorganics
(metals), such as aluminum, antimony, lead, and selenium were detected above the
statistically derived background number.  However, further analysis of these evaluated
concentrations of metals determined that they are also part of the background, based upon the
geologic depositional environment at Castle AFB.

As detailed in Table 3-3, the shallow, upper subshallow, and lower subshallow groundwater
zones within the plumes noted above, contain TCE, petroleum hydrocarbons, and other
organic and inorganic contaminants. These contaminants generally decrease in
concentrations with depth of the zone. The confined groundwater zones contain
contaminants at lower concentrations, and in fewer regions; and the deep groundwater zone
contains no contaminants in any of the regions.  The nature and extent of contaminants in
groundwater beneath Castle AFB is discussed below by HSZ.

3.5.1 Shallow HSZ. Nine TCE plumes have been identified within the seven plume regions.
Figure 3-6 shows the lateral extent of TCE in the shallow HSZ. The plume identified in the
Main Plume Regions is by far the most extensive. It contains the highest concentrations of
TCE with a maximum reported value of 740 ftg/L. The extent of TCE plumes in the other
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plume regions is much smaller. TCE concentrations in the other plume regions are much less
with a maximum reported TCE concentration of 45 jig/L in the East Base Plume Region.

PCE, chloroform, carbon tetrachloride, cis-l,2-DCE, and l,2-dibromo-3-chloropropane
(DBCP) plumes are also present in the Main Plume regions. These other plumes are within
the TCE plume of the Main Plume regions, with the exception of the DBCP plumes. DBCP
is an agricultural chemical regionally present in the groundwater and for which no Castle
AFB sources have been identified and is consequently not considered a COC.

A plume of cis-l,2-DCE, PCE, and TCE was identified in the Castle Vista Plume region, cis-
1,2-DCE being the primary contaminant of concern. Small plumes of PCE and DEHP were
identified in the North Base Plume region. The PCE plume is within the TCE plume in this
region, while the DEHP plume is located southwest of the TCE plume.  TCE is the only
organic 'compound for which plumes were identified in the Landfill  1, Landfill 4, and East
Base Plume regions. Within all seven plume regions, other organic chemicals were detected
at concentrations exceeding MCLs and Preliminary Remediation Goals (PRGs). However, in
most cases, these were isolated occurrences with insufficient data to define plumes. In
addition, the TCE plumes encompass the locations of these isolated occurrences.

3.5.2 Upper Subshallow HSZ. Groundwater contamination in the upper subshallow HSZ is
limited to the Main Plume Regions 1 and 2. TCE is the principal contaminant. The TCE
plume in the upper subshallow HSZ is smaller than the extent of the TCE plume in the
shallow HSZ. The concentrations of TCE in the upper subshallow HSZ (maximum reported
value of 160 lig/L) are lower than the concentrations in the shallow HSZ.

PCE and DBCP plumes are present in the Main Plume regions. The PCE plume is small and
occurs within the TCE plume.  The DBCP plume extends west of the TCE plume. Other
organic chemicals detected at concentrations exceeding MCLs and PRGs included
chloroform and DEHP. These are isolated occurrences with insufficient data to define
mappable plumes.

3.5.3 Lower Subshallow HSZ. TCE is the only mappable plume identified in the lower
subshallow HSZ and contamination is confined to the Main Plume regions. Concentrations
of TCE were generally lower than in the upper two HSZs, with the exception of a 190 pg/L
concentration in well MW863 (grid R,12).

3.5.4 Confined HSZ.  Contamination in the confined HSZ is limited to the Main Plume
regions with mappable plumes of TCE and benzene identified. The TCE plume in the
confined HSZ is smaller in size and relative concentration (maximum detected concentration
29 fig/L) than the TCE plume in the lower subshallow HSZ.  Two small plumes of benzene
are present in the confined HSZ with a maximum reported concentration of 1.6 Jig/L. Other
BTEX constituents are also reported, but none exceed MCLs or PRGs.
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3.5.5  Deep HSZ. Contaminants were not detected in the groundwater from the deep HSZ
well.

3.6    SUMMARY OF GROUND WATER PLUME RISKS

The CB-Part 1 RI/FS includes a Baseline Human Health Risk Assessment (BHHRA) that
includes 1) contaminant identification information, 2) potential exposure pathways, 3) the
toxicity of the Chemicals of Potential Concern (COPCs), and 4) an evaluation of the potential
human health risks and hazards associated with contaminated groundwater at Castle AFB in
the absence of RAs or institutional controls. Therefore, risk estimates are conservative in that
they do not reflect reductions in contamination arising from ongoing cleanup efforts where
groundwater remediation is currently in progress (e.g., OU 1). Ecological risks associated
with potential exposures of biota to soil and groundwater contaminants at Castle AFB have
been evaluated in the first of three phases of the Ecological Risk Assessment (ERA). It
should be noted that BHHRA uses conservative (i.e., health protective) hypothetical
assumptions to identify COPCs and to assess the possible impact of exposure to those
chemicals.

3.6.1  Human Health Risk Assessment The following discussion on Human Health Risk
Assessment for Castle AFB groundwater is based on the Castle CB-Part 1 RI/FS Volume 2 -
BHHRA Sections 4, 5, 6,7, and 8. The results of the BHHRA are summarized in Table 3-4.

3.6.1.1 Contaminant Identification Information. Groundwater sampling data obtained
from the RI was validated for usability in the risk assessment. Only the laboratory analytical
data that met or exceeded the EPA Level HI Quality Control guidelines were utilized.

A total of 66 analytes were reported as detected in groundwater samples collected on and off
base during field investigations; inorganics, VOCs, semi-volatile organic compounds
(S VOCs), Total Petroleum Hydrocarbons (TPH) (as gasoline and diesel) and radioactivity
(gross alpha and beta). Only contaminants detected in groundwater were included, with soil
contaminants being addressed in the SCOU BHHRA.

Not all analytes were selected as COPCs for evaluation in the risk assessment. EPA provides
several rationales for excluding chemicals from consideration as COPCs in  the risk
assessment.  These include the following: 1) reported concentrations of the chemical are due
to laboratory contamination, 2) reported concentrations of the chemical are representative of
naturally occurring levels, and 3) the chemical is an essential nutrient and is present at
concentrations that are unlikely to cause adverse health effects.

Certain detected analytes were thus excluded as COPCs. These were TPH (as gasoline and
diesel) and gross beta radiation.  Data reported as TPH is not suitable for risk  assessment
purposes, as the lexicological effects of the individual constituents must be  evaluated
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individually rather than as a group (i.e., hydrocarbons). Similarly, to evaluate health effects
due to exposure to radiation, it is necessary to identify individual radioisotopes in order to
quantitatively evaluate their health effects. Radionuclide levels identified at Castle AFB are
within the range expected from naturally-occurring sources.

Of the 66 analytes detected in groundwater, a total of 53 chemicals (13 inorganic and 40
organics) were identified as COPCs in groundwater at Castle AFB.  The COPCs are
presented in Table 3-5.  The contaminant of greatest concern is TCE.  TCE is a colorless
liquid that has been widely used as a metal degreasing agent in dry-cleaning processes; as a
solvent in refrigerants; and as a fumigant in pesticide activities.  It is a probable human
carcinogen; therefore, it is a contaminant that is associated with cancer risk.

3.6.1.2 Potential Exposure Pathways. In order to determine the magnitude, frequency,
duration, and route of exposure to the groundwater contaminants, potential  exposure
pathways were developed by identifying populations that currently, or may  in the future,
contact chemicals at the site and the potential routes of exposure. Exposure is the contact of
a chemical with a receptor; in this case a person. Magnitude is determined by estimating the
amount (concentration) of the chemical at the point of contact over a specified time period
(exposure duration) as well as the actual intake (dose) of the chemical.

The current land uses on Castle AFB proper are predominantly industrial with limited   .
residential use.  Residential areas are located west of Castle AFB and include off-base
housing,  trailer parks, suburban housing, and rural farm residences. However, within the 2-
mile radius around Castle AFB, the adjacent land use is primarily agricultural. Dependent  on
land use, potential receptors representative of the reasonable maximum exposure include the
on-site industrial worker, and on-site resident (adult and child).

Actual future land use of a site should also be considered when using risk estimates to drive
site RAs. Residential land use allows for the greatest exposure to contaminants; thus,
compliance with the most stringent standards are required. Therefore, if a site is not planned
for use as a residential area, and is unlikely to be considered desirable for development as a
residential area, the residential use scenarios may not be appropriate for developing cleanup
goals.

Currently, human receptors at Castle AFB are exposed only to groundwater that has been
filtered and treated to reduce groundwater contaminants to levels below those mandated by
federal and state drinking water standards (e.g., MCLs).  However, hypothetical future human
receptors may potentially be exposed through ingestion of untreated groundwater, ingestion
of produce irrigated with contaminated groundwater, dermal (skin) contact, and inhalation  of
chemicals volatilized from household uses of untreated groundwater.  Exposure pathways
evaluated in the BHHRA are presented in Table 3-6. Exposure point concentrations,
duration, and doses were estimated for 1) ingestion, 2) inhalation of volatiles while
showering, 3) dermal contact while showering, and 4) ingestion  of produce.

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3.6.13 Toxicity of Chemicals of Potential Concern. The toxicity of the COPCs was
assessed in two steps; hazard identification and dose-response assessment For each COPC,
it was determined whether exposure to that chemical may result in a deleterious health effect
in humans. This was done by characterizing the nature of the effect and the strength of the
evidence that the chemical will cause the observed effect Dose-response assessment
characterizes the relationship between the dose and the incidence and/or severity of the
adverse health effect in the exposed population.

Some of the COPCs identified in groundwater at Castle AFB are considered to be potential
human carcinogens.  However, both cancer risks and noncancer health hazards due to
exposure to these compounds were  evaluated in the BHHRA.

Cancer potency factors (CPFs) have been developed by EPA's Carcinogenic Assessment
Group for estimating excess lifetime cancer risks associated with exposure to potentially
carcinogenic chemicals. CPFs, which are expressed in units of (mg/kg-day), are multiplied
by the estimated intake of a potential carcinogen, in (mg/kg-day), to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure at that intake level.  The
term "upper-bound" reflects the conservative estimate of the risks calculated from the CPF.
Use of this approach makes underestimation of the actual cancer risk unlikely.  CPFs are
derived from results of human epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been applied.

Reference doses (RfDs) have been developed by the EPA for indicating the potential for
adverse health effects from exposure to chemicals exhibiting noncarcinogenic effects. RfDs,
which are expressed in units of mg/kg-day, are estimates of lifetime daily exposure levels for
humans, including sensitive individuals. Estimated intakes of chemicals from environmental
media (e.g.,  the amount of a chemical ingested from contaminated drinking water) can be
compared to the RfD. RfDs are derived from human epidemiological studies or animal
studies to which uncertainty factors have been applied (e.g., to account for the use of animal
data to predict effects on humans).  These uncertainty  factors help  ensure that RfDs will not
underestimate the potential for adverse noncarcinogenic effects to occur.

Toxicity values for COPCs used in the CD-Part 1 BHHRA are presented in Tables 3-7 and
3-8.

3.6.1.4 Potential Human Health Risks and Hazards Associated with Contaminated
Groundwater. Risk characterization presents both quantitative and qualitative expressions
of the likelihood of adverse effects on the potentially exposed populations. This is achieved
through integration of the information gathered in the  exposure assessment and toxicity
assessment.
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Risk characterization is performed separately for carcinogenic and noncarcinogenic effects.
Carcinogenic risk is expressed as the probability that an individual will develop cancer over a
lifetime as a result of exposure to the potential carcinogen.  Noncarcinogenic hazards are
characterized by comparing the estimated exposure level over a specified period of exposure
with RfDs to provide a numeric estimate of the likelihood of a toxic response.

Excess lifetime cancer risks are determined by multiplying that intake level with the CPF.
These risks are probabilities that are generally expressed in scientific notation (e.g., 1.0 x 10"*
or 1E-6).  An excess lifetime cancer risk of 1.0 x 10"6 indicates that, as a plausible upper-
bound, an individual has a one in one million chance of developing cancer as a result of site-
related exposure to a carcinogen over a 70-year lifetime under the specific conditions at a
site.

Cancer risk is expressed as the probability that an individual will develop cancer over a
lifetime as a result of exposure to the potential carcinogen for a long period (30 years).  The
guidance for calculating risks to human populations uses a range of cancer risk as a target for
establishing health protection goals.  The target risk range for cancer is 100 in one million
(10"4) to one in one million (10"6).

Potential concern for noncarcinogenic effects of a single contaminant in a single medium is
expressed as a hazard quotient (HQ)  (or the ratio of the estimated intake derived from the
contaminant concentration in a given medium to the contaminant's RfD). By adding the HQ
for all contaminants within a medium or across all media to which a given population may
reasonably be exposed, the Hazard Index (HE) can be generated.  The HI provides a useful
reference point for gauging the potential significance of multiple contaminant exposures
within a single medium or across media.

An HI above one  indicates that someone exposed to the contamination may experience some
adverse health effects.

As indicated in Table 3-6, three exposure scenarios were evaluated. The results of the risk
characterization show that VOCs in general and TCE in particular are the primary
contributors to the estimated carcinogenic risk and hazard basewide. Ingestion and dermal
absorption are the primary exposure  routes contributing to the overall risk. Risks resulting
from ingestion comprise between 25 to 60 percent of the total risk, while risks from the
dermal pathway account for between 30 and 60 percent of the total. Inhalation of volatilized
chemicals and food chain transfer via plant uptake are minor pathways, and account for
approximately 4 and 8 percent, respectively, of the total risk.

In the following sections, the risks/hazards resulting from exposure to COPCs are described
for each of the plumes and HSZs.
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Main Plume Region 1: Shallow HSZ. TCE is the most prevalent organic contaminant
found in the Main Plume Region 1 shallow HSZ. The total estimated upper-bound
carcinogenic risk for the adult residential receptor is 9.0 x 10~5. TCE is the primary
contributor and accounts for 72 percent of the total estimated risk. The estimated risk
associated with 1,1-dichloroethene (1,1-DCE), hexa-chlorobutadiene, and PCE contribute to
5 percent or more of the total risk.  The total HI is 2.67 and the primary contributor to the
total HI is TCE, which has an individual HQ greater than 1.

The total estimated upper-bound carcinogenic risk for the child residential receptor is 4.2 x
10"5. TCE is the primary contributor to the estimated risk total. The total HI is 6.54.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
4.1 x 10~5. TCE is the primary contributor to the total with 1,1-DCE and PCE having
individual contributions of 5 percent or greater to the  total estimated risk.  The total HI is
1.42 and TCE is the only COPC with an individual HQ greater than 1.

Main Plume Region 1: Upper Subshallow HSZ. TCE is the most widespread organic
contaminant found in the upper subshallow HSZ. The total estimated upper-bound
carcinogenic risk for the adult residential receptor is 2.2 x 10"4. The primary contributors to
the estimated risk are arsenic, TCE, and DBCP. The total HI is 4.15, and TCE is the primary
contributor to the total HI.

The total estimated upper-bound carcinogenic risk for the child residential receptor is 4.2 x
10~5. Arsenic, TCE, and DBCP are the primary contributors to the total risk. The total HI is
9.81, and TCE is the primary contributor to the HI, although arsenic and DBCP also have
individual HQs greater than 1.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
8.6 x 10'5. Arsenic and TCE are the primary contribetors to the total estimated risk with the
individual risk associated with DBCP greater than 5 percent of the total. The total HI is 2.12,
and TCE is the only COPC with an individual HQ greater than 1.

Main Plume Region 1: Lower Subshallow HSZ. Carbon tetrachloride, cis-l,2-DCE, PCE,
and TCE are the most commonly reported organic analytes in the Main Plume 2 lower
subshallow HSZ. The total estimated upper-bound carcinogenic risk for the adult residential
receptor is 1.9 x 10"5. PCE and TCE are the primary contributors to this risk, although carbon
tetrachloride also contributes greater than 5 percent of the total. The total HI is less than 1
and TCE is the primary contributor to the total HI.
The total estimated upper-bound carcinogenic risk for the child residential receptor is 8.4 x
 10~5.  PCE and TCE are the primary contributors to the total risk, although benzene and
carbon tetrachloride also have individual risks that contribute 5 percent or greater of the total.
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The total HI is 1.44, and TCE contributes more than half of the estimated HI, although its
individual HQ is less than 1.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
8.9 x 10"6. PCE and TCE are the primary contributors to the total estimated risk with the
individual risk associated with carbon tetrachloride greater than 5 percent of the total. The
total HI is less than 1, and TCE is the primary contributor to the HI.

Main Plume Region 1:  Confined HSZ. The total estimated upper-bound carcinogenic risk
for the adult residential receptor is 2.6 x 10"4.  Arsenic is the primary contributor to this risk,
although TCE also has an individual risk of 5 percent or greater of the total risk. The total HI
is 3.90, and arsenic is the only COPC with an individual HQ greater than 1.

The total estimated upper-bound carcinogenic risk for the child residential  receptor is 1.2 x
10"4. Arsenic is the primary contributor to the total estimated risk, although TCE has an
individual risk that contributes 5 percent or greater of the total. The total HI is 9.23,  and both
arsenic and TCE have individual HQs greater than 1.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
8.3 x 10"5. Arsenic is the primary contributor to the total estimated risk with the individual
risk associated with TCE greater than, 5 percent of the total. The total HI is 1.55. Although
no single COPC has an individual HQ greater than 1, arsenic is the primary contributor to the
estimated total hazard.

Main Plume Region 2:  Shallow HSZ. TCE is the most prevalent organic contaminant
found in the Main Plume Region 2 shallow HSZ. The total estimated upper-bound
carcinogenic risk for the  adult residential receptor is  1.9 x 1(T*. Ethylene dibromide (EDB)
and TCE are the primary contributors and together account for 86 percent of the total
estimated risk. DBCP also accounts for greater than*5 percent of the total estimated risk.
The total HI is 2.87, and  the primary contributors to the total HI are DBCP and TCE, with the
HQ for TCE greater than 1.

The total estimated upper-bound carcinogenic risk for the child residential  receptor is 9.1 x
10~5. EDB and TCE are the primary contributors to the estimated risk total, and together
account for 95 percent of the total risk.  DBCP also accounts for greater than 5 percent of the
total estimated risk. The total HI is 6.95, and both DBCP and TCE have individual HQs
greater than 1,

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
7.0 x  10"s. EDB and TCE are the primary contributors to the total and together account for
96 percent of the total estimated risk. DBCP also accounts for greater than 5 percent of the
total estimated risk. The total HI is 1.51, and TCE is the primary contributor to the HI and
the only COPC with an individual HQ greater than 1.

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Main Plume Region 2: Upper Subshallow HSZ. DBCP and TCE are the most prevalent
organic contaminants found in the Main Plume Region 2 upper subshallow HSZ. The total
estimated upper-bound carcinogenic risk for the adult residential receptor is 1.8 x 10"4.  TCE
is the primary contributor to the total estimated risk. DBCP and EDB, although less widely
distributed than TCE, have individual contributions of 18 and 33 percent, respectively,  to the
cumulative total.  The total HI is 3.21, and the primary contributors to the total HI are DBCP
and TCE, with each having an individual HQ greater than  1.

The total estimated upper-bound carcinogenic risk for the child residential receptor is 9.1 x
10~5. DBCP, EDB, and TCE are the primary contributors to the estimated risk total.  The
total HI is 8.19, and both DBCP and TCE have individual HQs greater than 1.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is 6.3 x
10'5. EDB and TCE are the primary contributors to the total risk. The total HI is 1.59,  and
TCE is the primary contributor to the HI and the only COPC with an individual HQ greater
than 1.

Main Plume Region 2: Lower Subshallow HSZ.  Only one well was screened in the Main
Plume Region 2 lower subshallow HSZ, and TCE was the only COPC identified. Because of
this limited amount of data, the spatial distribution of TCE in the HSZ is unknown, and the
calculated risks and hazards are based on an assumed plume-wide exposure to the single
measured concentration. The estimated upper-bound carcinogenic risks are 2.9 x 10"6 for the
adult residential receptor, 1.3 x 10"6 for the child residential receptor, and 1.4 x 10"6 for the
occupational receptor.  The HI is less than 1  for all evaluated exposure scenarios.
Main Plume Region 2: Confined HSZ. Three monitoring wells were screened in the Main
Plume Region 2 confined HSZ. Because of the limited amount of data, statistical analyses
were not performed, and the estimated risk and hazard is based on an assumed plume-wide
exposure to the maximum detected concentration for each analyte. Benzene is the primary
contributor to the total estimated risk and accounts for 60 percent or more of the cumulative
total in all exposure scenarios evaluated. The estimated upper-bound carcinogenic risks are
3.0 x 10"6 for the adult residential receptor, 1.4 x 10"6 for the child residential receptor, and
1.2 x 10"6 for the occupational receptor.  The HI is less than 1 for all evaluated exposure
scenarios.

Landfill 4 Plume Region.  PCE and TCE are the most commonly reported organic
contaminants found in the Landfill 4 region shallow HSZ. The total estimated upper-bound
carcinogenic risk for the adult residential receptor is 1.7 x 10**. Arsenic and DEHP are the
primary contributors to the total estimated risk. The total HI is 4.05, and arsenic is the only
COPC with an individual HQ greater than 1.
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The total estimated upper-bound carcinogenic risk for the child residential receptor is 9.3 x
10"5. Arsenic and DEHP are the primary contributors to the estimated risk total.  The total HI
is 9.34, and antimony, arsenic, DEHP, and DBCP have individual HQs greater than 1.
The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
4.4 x
1.70.
4.4 x 10"5. Arsenic and DEHP are the primary contributors to the total risk.  The total HI is
North Base Plume Region. DEHP and dichlorodifluoromethane are the most frequently
reported organic COPCs found in the North Base Plume region shallow HSZ.  The total
estimated upper-bound carcinogenic risk for the adult residential receptor is 5.2 x 10'5.
DEHP, PCE, and vinyl chloride are the primary contributors to the total estimated risk. The
total HI is less than 1.

The total estimated upper-bound carcinogenic risk for the child residential receptor is 3.6 x
10"5. DEHP, PCE, and vinyl chloride are the primary contributors to the estimated risk total.
The total HI is 1.40, and DEHP is the only COPC with an individual HQ greater than 1.

The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
1.0 x 10"5. DEHP, PCE and vinyl chloride are the primary contributors to the total risk,
although methylene chloride and TCE also have individual risks greater than 5 percent of the
cumulative total. The total HI is less than 1.

East Base Plume Region. TCE is the most frequently reported organic COPC found in  the
East Base Plume region shallow HSZ. The total estimated upper-bound carcinogenic risk for
the adult residential receptor is 8.7 x 10"5. The total HI is less than 1.
The total estimated upper-bound carcinogenic risk for the child residential receptor is 4.2 x
10"5. The total HI is 1.61, an<
individual HQ is less than 1.
10's. The total HI is 1.61, and arsenic is the greatest contributor to the total HI although its
The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
2.6 x  10'5. The total HI is less than 1.

Landfill 1 Plume Region: Shallow HSZ. Chloroform and PCE are the most frequently
reported organic COPCs found in the Landfill Plume Region 1 shallow HSZ. The total
estimated upper-bound carcinogenic risk for the adult residential receptor is 2.9 x 10"4.
Arsenic 1) accounts for greater than 95 percent of the estimated carcinogenic risk, 2) is the
most significant contributor to the HI for all three scenarios, and 3) has an individual HQ
greater than 1 in all three scenarios.

The total estimated upper-bound carcinogenic risk for the child residential receptor is 1.4 x
1Q-4.  The total HI is 4.36.

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The total estimated upper-bound carcinogenic risk for the adult occupational scenario is
8.6 x 10'5. The total HI is less than 1.

Landfill 1 Plume Region: Upper Subshallow HSZ. Two monitoring wells were screened
in the Landfill 1 upper subshallow HSZ. Because of the limited amount of data, statistical
analyses were not performed, and the estimated risk and hazard is based on an assumed
plume-wide exposure represented by the well with maximum detected concentration for each
analyte. In all three exposure scenarios evaluated, TCE is the primary contributor to the total
risk.

The estimated carcinogenic risks are 4.7 x 10'7 for the adult residential receptor, 2.3 x 10~7 for
the child residential receptor, and 2.2 x 10"7 for the occupational receptor. The HI is less than
1 for all three evaluated exposure scenarios.

Castle Vista Plume Region: Cis-l,2-DCE and PCE were each detected in two wells and
were the only contaminants detected in more than one well in the Castle Vista Plume region
shallow HSZ. The estimated carcinogenic risks are  1.1  x  10"4 for the adult residential
receptor, 5.2 x 10'5 for the child residential receptor, and 4.2 x 10'5 for the occupational
receptor. The HI is less than 1 for all three evaluated exposure scenarios.

Uncertainty Analysis. The presence of uncertainty is inherent in the risk assessment
process.  The sources of uncertainties in risk assessment range from the assumptions and
methodologies used in the evaluation of exposures and risks to data gaps in the qualitative
and quantitative information used to characterize site COPCs. Acknowledgment of the
uncertainties present is necessary to appropriately evaluate risk assessment results, and assists
in the identification of any further investigations that may be required. The uncertainties
associated with the CB-Part 1 BHHRA for Castle AFB result from limitations in the
available methods, information, and data.
                                             *•'
Human Health Risks and Hazards Summary.  The human health risk assessment
evaluated the current and future risks to exposed populations under several different
scenarios. Table 3-4 summarizes the results of the risk assessment for the plumes identified
in the RI/FS.  The table identifies the highest calculated cancer risks and hazards for the
scenarios evaluated:  the adult residential, the child  residential, and the adult occupational
scenarios. In this table, it can be seen that some plume regions have cancer risk estimates
that are above the upper limit of the target risk range (1.0 x 10"*), while others are below this
limit.  In addition, some of the plume regions have His that exceed 1.0, suggesting that a
health  hazard may be posed under the scenario considered.

Other factors, besides risk and hazard index, were taken into consideration when determining
the need to implement RAs for groundwater plumes. These factors include contaminant
mass, areal extent of the contaminant plume, and other plume characteristics. Based on all
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factors considered, the Main Base Plume and East Base Plume were advanced for further
detailed evaluation in the CB-Part 1 FS. In addition, the Castle Vista Plume was recognized
in the RI/FS as requiring additional characterization to determine whether or not RA was
warranted.

For the North Base, Landfill 1, and Landfill 4 Plumes, the mass of contaminants and the area]
extent of contamination are small and are associated with isolated detections. Remediation
would not be technically or economically feasible, nor would it significantly enhance the
beneficial uses of groundwater. As a result of these factors, no further active remediation is
planned for the North Base, Landfill 1, and Landfill 4 plumes. However, these plumes will
continue to be monitored under the LTGSP.

If the actual or threatened migration of contaminated groundwater at Castle AFB  is not
addressed by implementing the remedial response actions selected in this ROD, contaminated
groundwater at Castle AFB may present an imminent and substantial endangerment to public
health, welfare, and/or the environment. Although groundwater cleanup actions are
underway in the area of OU 1 and OU 2, there are additional areas of groundwater
remediation that are not currently being addressed; it is the purpose of CB-Part 1 to address
the need for further groundwater remediation.

3.6.2 Ecological Risk Assessment (ERA).  The scoping and Phase I ERA was completed in
December 1995 as a portion of the CB-Part  1 RI/FS. The goal of the Phase I ERA was to
evaluate the possible adverse ecological effects of past and current on-site chemical
contaminants to ecological receptors.  The ERA contains two other phases, each dependent
on the results of the preceding phase.  Phase n is the Validation/Verification Assessment,
which reduces the uncertainty in Phase I. Phase in is the Remedial Assessment, which is a
focused investigation to identify the remedial objectives. The Phase n ERA is scheduled to
be completed in December 1996 and will be included in the final documentation of CB-Part
2 RI/FS.

The groundwater at Castle AFB is located approximately 70 to 80 feet below ground level
and does not recharge to the surface.  Since it is too deep for ecological receptors to contact,
groundwater is not considered a medium of concern for the ERA. However, this medium
may need to be considered in the future if reuse plans for Castle AFB are changed to include
agricultural uses, which could expose surface receptors to groundwater via irrigation.
Institutional controls prohibiting pumping from contaminated groundwater plumes should
preclude exposure of surface receptors to the contaminated water.

3.63 Screening of Contaminants and Groundwater Plume Regions.  The seven
groundwater plumes and contaminants identified in Section 3.5 were screened for
consideration of RA by using the following five step process illustrated in Figure 3-7.  For
those plumes and contaminants identified for consideration of RA, preliminary RA options
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were formulated. The following conclusions were derived from the results that are
summarized in Section 2 of the CB-Part 1 FS.

3.63.1 Groundwater Plume and Contaminant Screening Process. The screening process
for evaluating groundwater plumes and contaminants for further consideration of remedial
analysis included the following interrogative steps.

•  Step 1.   Chemicals which occur regionally in groundwater either naturally (e.g.,
   arsenic) or due to regional contamination (e.g., DBCP and EDB), and are not due to
   Castle AFB sources were eliminated from the list of potential COCs.
•  Step 2.   Within each plume region and HSZ, the risks and hazards associated with
   individual COPCs were evaluated and the concentrations of the COPCs were compared to
   ARARs. The individual COPCs for which the risk exceeds 10^, the ffl exceeds 1.0, or
   the exposure point concentration exceeds the associated ARARs were retained. All other
   COPCs not previously excluded were eliminated in this step.
•  Step 3.   Those COPCs determined to have mappable groundwater plumes were
   identified.  COPCs which were only detected in isolated locations and for which no
   mappable plumes were identified were forwarded for consideration in the LTGSP for
   filling of data gaps and continuation of monitoring.
•  Step 4.   The groundwater plumes of COCs identified, following the screening process
   in the first three steps, were evaluated to determine plumes for the development and
   analysis of RA alternatives.  This evaluation included consideration of the areal extent
   and mass of the plume, the plume location, and comparison of the contaminant
   concentration to the associated MCL.  Plumes for which development of RA alternatives
   was not considered appropriate at this time were forwarded for consideration in the
   LTGSP for filling of data gaps and continuation of monitoring.
•  Step 5.    Preliminary Remedial Action Options (PRAOs) were developed for those
   COC plumes retained after the four screening steps described above. These PRAOs were
   utilized as the basis for development of potential RA alternatives in the FS.  •

The following sections present the application of this screening process to each of the seven
plume regions at Castle AFB.

With respect to step 1 of this process, arsenic, DBCP, and EDB were eliminated as COCs for
the reasons discussed in the following paragraphs.

Arsenic was chosen as an analyte during the CB Groundwater RI because it could have been
released during routine aircraft maintenance operations or from common solid wastes in
landfills, and it had been detected previously in groundwater at Castle AFB. Arsenic and
other metals were detected in wells located in all parts of Castle AFB, including background
monitoring wells. Arsenic has also been detected in a significant number of shallow wells in
the San Joaquin Valley. The City of Atwater Annual Water Quality Report for 1995 reports
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arsenic concentrations in eleven water supply wells ranging from nondetect to 9 ug/L, with
an average of 2.9 ug/L.

Although several inorganic analytes with concentrations exceeding the TBV95 values may be
found in single wells, no definable plumes of arsenic or other inorganic constituents have
been identified in any of the HSZs at Castle AFB.  Where arsenic is detected, concentrations
tend to be highest in the shallow HSZ, as is the case for all of the detected inorganics. The
highest concentrations (20 and 17 ug/L) of arsenic occur beneath Landfill 1. Other elevated
concentrations appear beneath Landfill 4(12 ug/L) and at the east boundary of the base (11
ug/L).  All other concentrations are well below 10 ug/L, generally in the 2 to 5 ug/L range,
and do not appear to be from Castle AFB sources.  Exposure point concentrations do no
exceed the MCL of 50 ug/L. The close relationship among the metal concentrations suggest
that there has not been and should not be a significant amount of metals transport via
advection of groundwater in the future. Based on 1) the low concentrations (below MCL) of
arsenic at Castle AFB, 2) the constituent relationship of these detections with other metals, 3)
the fact that the metals concentrations are conservative due to being total metals, and 4) the
general occurrence of arsenic at detectable concentrations below the MCL throughout the San
Joaquin Valley, arsenic is considered to be present as a regionally-occurring groundwater
characteristic, and the concentrations reported in groundwater at Castle AFB, with the
exception of the Landfill 1 and Landfill 4 Plume regions, are attributed to the regional
occurrence.  Although past activities at Landfill 1 and Landfill 4 may have contributed
arsenic to groundwater, the concentrations are below the MCL of 50 ug/L, the plumes are
relatively small, and the mass of contaminants possibly related to Castle AFB is small.

DBCP and EDB have no remedial  goals, and they are not considered COCs. No PRAOs
were developed for these chemicals because they are agricultural contaminants commonly
found in groundwater in the area around Castle AFB (Step 1).

3.6.3.2 Main Base Plume Regions. The organic COPCs that individually exceed
carcinogenic risks of  1.0 x 10"6 or a hazard index of 1, include benzene, carbon tetrachloride,
EDB, DEHP, 1,1-DCE, cis-l,2-DCE, hexachlorobutadierie, methylene chloride, PCE, TCE,
and DBCP. The exposure point concentrations of carbon tetrachloride, DEHP, EDB, 1,2-
DCE, TCE, and DBCP exceed MCLs.  The inorganic COPC that individually exceeds a
carcinogenic risk of 1.0 x 10"* or a hazard index of 1 is arsenic. For the reasons discussed
above, arsenic, DBCP and EDB are not considered COCs based on step 1 of the screening
process.

The COCs for the Main Base Plume regions are benzene, chloroform, carbon tetrachloride,
cis-l,2-DCE, PCE, and TCE. Based on total mass and associated risk, the principal COC for
the Main Plume region is TCE.  Contamination occurs in the shallow, upper subshallow,
lower subshallow, and confined HSZs. The extent of the TCE plume encompasses the extent
of other organic contaminants present,  with the exception of DBCP, which is not considered
a COC, and benzene.
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Two groundwater extraction systems have either been installed (OU 1) or are under
construction (OU 2) to address TCE contamination within the shallow and upper subshallow
HSZs in the Main Base Plume regions. The Main Base Plume accounts for 98 percent of the
TCE mass and 95 percent of the TCE-contaminated groundwater volume at Castle AFB
based on the 0.5 (ig/L (detection limit) plume boundaries (Table 3-1).

Three PRAOs for TCE were defined for the Main Base Plume:

•  Capture and cleanup of TCE to the MCL of 5 |ig/L
•  Capture and cleanup of TCE to 3 jig/L
•  Capture and cleanup of TCE to the detection limit of 0.5 ug/L

These PRAOs were based on an agreement between the AF and the regulatory agencies to
consider these levels; as documented in the ROD for OU 2 (AF 1993). The ultimate basis for
the first of these levels is the chemical-specific ARAR that defines the MCL for TCE. The
third PRAO was based on the detection limit for TCE, and the second PRAO represents the
EPA Alternative Water Quality Criteria (AWQC) for health and welfare protection.

The PRAOs for the other COCs were  set at their respective MCLs.
                                                                 i
3.63.3 East Base Plume Region. The East Base Plume region is located beneath two sites
with known soil contamination; FTA-1 and B1762 sites. Groundwater contamination is
limited to the shallow HSZ.

The organic COPCs that individually  exceed a carcinogenic risk of 1.0 x 10"6 or an HI of 1
include bromodichloromethane, DEHP, carbon tetrachloride, PCE, and TCE. Exposure point
concentrations exceed the MCL for DEHP.  The inorganic COPC that exceeds a carcinogenic
risk of 1.0 x 10"6 or an HI of 1 is arsenic. Based on the above screening criteria, arsenic (step
1) was excluded from consideration as a COC.

DEHP, bromodichloromethane, carbon tetrachloride, and PCE were also excluded from
remediation because they are only detected in isolated locations defining small plumes with
low concentration and small total  mass. Remediation of these plumes has been determined to
be economically or technically infeasible and impractical.  Further, beneficial uses of the
groundwater have not been significantly impacted. These contaminants will be monitored
under the LTGSP.

The COC  identified for the East Base Plume region is TCE. Three PRAOs for TCE are
defined for the East Base Plumes:

•  Capture and cleanup of TCE to the MCL of 5 ug/L
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•  Capture and cleanup of TCE to 3 ug/L
•  Capture and cleanup of TCE to the detection limit of 0.5 ug/L

The rationale for the selected PRAOs is similar to that for the Main Base Plume.

3.63.4 Landfill 4 Plume Region. The Landfill 4 Plume region is located beneath Landfill 4
in the West Base Sector.  Contamination is in the shallow HSZ. The organic COPCs that
individually exceed a carcinogenic risk of 1.0 x 10* or an HI of 1 includeJ>enzene, DEHP,
DBCP, and PCE.  The exposure point concentrations of DEHP and DBCf^exceedjhe MCLs.
The inorganic COPCs that individually exceed carcinogenic risks-ofTcf^ or an HI of
include arsenic and antimony.                                                 ~^~^

Based on the above screening criteria, antimony, arsenic, benzene, DBCP, DEHP, and PCE
are not considered to be COCs for the following reasons. Arsenic is excluded because it is
present as a groundwater characteristic throughout the San Joaquin Valley. DBCP is
excluded from consideration as a COC because it is an agricultural contaminant commonly
found in groundwater in the area around Castle AFB.  Antimony, benzene, DEHP,  and PCE
are excluded because they are only detected in isolated locations and the detections were not
defined as plumes in the RI. These contaminants will be monitored under the LTGSP.

There are no COCs for the Landfill 4 Plume region based on these results. Therefore, no
RAs are considered necessary for the Landfill 4 Plume and no PRAOs are defined.
Remediation of these plumes has been determined to be economically or technically
infeasible and impractical. Further, beneficial uses of the groundwater have not been
significantly impacted. This plume region would be forwarded to the LTGSP.

3.63.5 North Base Plume Region. The North Base Plume region is located beneath
Landfill 5 in the North Base Sector. Contamination has been detected in the shallow HSZ.
The organic COPCs that individually exceed a carcinogenic risk of 1.0 x 10"6 or an HI of 1
include benzene, DEHP,  1,4-dichlorobenzene, methylene chloride, PCE, TCE, and vinyl
chloride. The exposure point concentration of DEHP exceeds the MCL.

Benzene, 1,4-dichlorobenzene, methylene chloride, and vinyl chloride are not considered to
be COCs because they are only detected in isolated locations defining small plumes with low
concentration and small total mass. Remediation of these plumes has been determined to be
economically or technically infeasible and impractical and would not significantly enhance
the beneficial uses of groundwater. Further, beneficial uses of the groundwater have not been
significantly impacted. These contaminants will be monitored under the LTGSP.

3.63.6 Landfill 1 Plume Region. The Landfill 1  Plume is located beneath Landfill 1 in the
South Base Sector. Contamination is in the shallow HSZ.
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PCE is the only organic COPC that individually exceeds a carcinogenic risk of 1.0 x 10"6 or
an HI of 1. Arsenic is the only inorganic COPC that individually exceeds a carcinogenic risk
of 1.0 x 10"* or an HI of 1. Exposure point concentrations do not exceed MCLs for any
COPCs. No further active remediation was selected for Landfill 1.

For the reasons discussed above, arsenic is not considered to be a COC, based on step 1 of
the screening process. PCE was excluded from remediation because it was detected only in
isolated locations defining small plumes with low concentration and small total mass.

TCE was identified as the COC for Landfill 1.

3.63.7 Castle Vista Plume Region. The Castle Vista Plume is located beneath Castle Vista
Landfill B in the off-base sector. Contamination is in the shallow HSZ.

The COPCs that individually exceed a carcinogenic risk of 1.0 x 10"6 or an HI of 1 are
benzene, EDB, and PCE.  Exposure point concentrations exceed MCLs for cis-l,2-DCE,
EDB, and PCE.  EDB and benzene are excluded from consideration for the following
reasons.

Benzene is excluded because it is only detected in  isolated locations and it is not possible to
define a plume. This contaminant will be monitored under the LTGSP. PRAOs were not
developed for EDB because it is an agricultural contaminant commonly found in groundwater
in the Castle AFB area.

The COCs for the Castle Vista Plume region based on these results are cis-l,2-DCE and
PCE. There is less than 3 pounds of either compound present, and the areal extent of the
plumes is limited.  Therefore, no active  RAs were  originally recommended in the RI/FS for
the Castle Vista Landfill Plume and no PRAOs were defined.

Subsequent to the completion of the RI/FS, new monitoring information from data gap wells
indicated the need for active remediation.  In April and May 1996, three monitoring wells
(MW935,936 and 937) were installed in the shallow HSZ, downgradient of the Castle Vista
Plume to fill data gaps that had been previously identified in the LTGSP and in the CB-Part 1
RI/FS. Two initial rounds of sampling were carried out at these wells; in addition,
groundwater samples were collected from two existing monitoring wells (MW002 and 003)
in the Castle Vista area.

The results of these two rounds of sampling indicated an elevated level of volatile organic
compounds in the Castle Vista plume. Samples at MW936 indicated elevated levels of cis-
1,2-DCE (48  and 90 ng/L); TCE (.72 and 1.2 ug/L); and PCE (4.8 and 8.3 pg/L).  In
addition, elevated levels of these compounds were also found at the existing monitoring
wells, MW002 and 003. Because these levels indicate that groundwater contamination
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exceeds MCLs and presents a greater extent of contamination than was previously evaluated
in the CB-Pait 1 RI/FS, the AF, with regulatory agency concurrence, has decided to
implement an active pump and treat remedy as a presumptive remedy for this plume.

3.7    DESCRIPTION OF THE ALTERNATIVES

To clean up the contaminated groundwater of the Main and East Base Plumes at Castle AFB,
a wide  range of possible alternatives were considered in the CB-Part 1 FS. In general, there
are many potential options available to remediate groundwater. The most promising options
for the  Main and East Base Plumes were chosen on the basis  of effectiveness,
implementability, and cost. Each alternative is discussed on the following pages.

Currently, there are two groundwater treatment systems (OU  1 and OU 2) in the RD/RA
phase.  The OU I groundwater extraction and treatment system began operating in July 1994
to remediate groundwater in the shallow HSZ within the Main Base Plume Region 1. OU 2
RAs are being implemented to address groundwater contamination in the shallow and upper
subshallow HSZs within the Main Base Plume regions. The DA-4 removal action operated
to remove contaminated groundwater from the shallow HSZ within Main Base Plume Region
2. The Wallace Road groundwater extraction and treatment system began operating in
December 1991 to remediate groundwater in the shallow and upper subshallow HSZs within
Main Base Plume Region 2.  The Wallace Road system is scheduled to be shut down and
replaced by the OU 2 extraction and treatment system. This will provide for expanded
remediation of groundwater in the shallow and upper subshallow HSZs within Main Base
Plume  Region 2.

The remedial alternatives selected for analysis in the CB-Part 1 FS include a combination of
groundwater extraction and treatment options, generally referred to as pump and treat. Each
pump and treat alternative combines processes from the following four categories:

•  Groundwater extraction
•  Groundwater treatment
•  Disposal of treated  water
•  Monitoring of remedial systems

The groundwater treatment options considered were:

•  Air Stripping
•  Advanced oxidation using ultraviolet (UV) light and an oxidizing chemical
•  Liquid-phase granular activated carbon (L-P GAC) adsorption

After the treated groundwater is discharged from the treatment system, it can be reinjected
using injection wells, released to a surface discharge location near the treatment system, or
otherwise reused.  Reinjection has been included since it gives the option of conserving the

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groundwater resources in the area, and creating a hydraulic barrier to help contain the plume.
Surface discharge to irrigation canals provides seasonal beneficial use of extracted
groundwater to local agricultural interests, and the existing irrigation canals have the capacity
to handle the large volumes of discharge expected.  In addition, the supplying of treated water
for beneficial reuse may offset regional production well drawdown of groundwater levels.
Groundwater cleanup  activities to date at Castle AFB (i.e., those conducted under OU 1 and
the removal actions at Wallace Road and DA-4) have included both reinjection and surface
discharge. Other reuse options have been the subject of ongoing discussions with local water
authorities. The AF is currently conducting a water reuse study to further evaluate future
reuse options.

Main Base Plume Remedial Alternatives. The CB-Part 1 FS combined the extraction,
treatment, and disposal options selected from screening of the technologies and process
options to form the following remedial  alternatives for the Main Base Plume.

1. No Action
2. Impacted area well-head treatment
3. Extraction of Groundwater above 5 ug/L TCE combined with:
   A) Air Stripping and Canal Discharge
   B) Air Stripping with L-P GAC Adsorption and Canal Discharge
   C) UV/Oxidation and Reinjection
   D) L-P GAC Adsorption and Reinjection
4. Extraction of Groundwater above 0.5 ug/L TCE combined with:
   A) Air Stripping and Canal Discharge
   B) Air Stripping with L-P GAC Adsorption and Canal Discharge
   C) UV/Oxidation and Reinjection
   D) L-P GAC Adsorption and Reinjection
5. Extraction of Groundwater above 3 ug/L TCE combined with:
   A) Air Stripping and Canal Discharge          *
   B) Air Stripping with L-P GAC Adsorption and Canal Discharge
   C) UV/Oxidation and Reinjection
   D) L-P GAC Adsorption and Reinjection
6. Extraction for Plume Control combined with impacted well-head treatment
   A) Air Stripping and Canal Discharge
   B) Air Stripping with L-P GAC Adsorption and Canal Discharge
   C) UV/Oxidation and Reinjection
   D) L-P GAC Adsorption and Reinjection

East Base Plume Remedial Alternatives. The following remedial alternatives were
subjected to a detailed analysis in the CB-Part 1 FS for the East Base Plume.

1. No Action
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2. Impacted Area Well Destruction and Monitor
3. Extraction of Groundwater above 5 ug/L TCE combined with:
   A) Air Stripping and Reinjection
   B) UV/Oxidation and Reinjection
   Q L-P GAC Adsorption and Reinjection
4. Extraction of Groundwater above 0.5 ug/L TCE combined with:
   A) Air Stripping and Reinjection
   B) UV/Oxidation and Reinjection
   C) L-P GAC Adsorption and Reinjection
5. Extraction of Groundwater above 3 ug/L TCE combined with:
   A) Air Stripping and Reinjection
   B) UV/Oxidation and Reinjection
   C) L-P GAC Adsorption and Reinjection

To reduce redundancy and facilitate review, both the Main and East Base Plume remedial
alternatives are discussed together in the following sections.

3.7.1  Alternative 1:  No Action

Main Base Plume. CERCLA requires evaluation of a No Action alternative.  However, at
Castle AFB the No Action alternative involves implementation of existing (OU 1) and ,
planned (OU 2) groundwater remediation systems. Long-term groundwater monitoring will
also continue throughout the operating systems to ensure that each system attains its
remediation goals. Therefore, the Castle AFB CB-Part 1  RI/FS No Action groundwater
remediation option/alternative is applicable only to any groundwater contamination not
captured by the OU 1 and OU 2 systems. This alternative also assumes 30 years of continued
monitoring for the 244 existing monitoring wells associated with the Main Base Plume.
                                              *-•
This alternative has the lowest overall cost at approximately $2.9 million. Factors which may
affect the cost of this alternative are well maintenance and structural repairs of existing wells
due to deterioration over time.

The No Action alternative is not expected to meet PRAOs. Natural intrinsic processes of
biodegradation and adsorption may control the spread of the plume. While being technically
feasible, acceptance by community and regulatory agencies is unlikely. Costs for the first 15
years of monitoring are included as part of the Castle AFB OU 1 and OU 2 RAs, and the
Castle AFB LTGSP.

East Base Plume. The No Action alternative would involve up to 30 years of continued
monitoring of the 44 existing monitoring wells associated with the East Base Plume region.
Since no action would be taken to contain the contaminant plumes or reduce the TCE
concentrations (or other COCs) in the plumes, this alternative would not meet the PRAOs.
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This alternative may be considered easier to implement for the East Base Plume region than
for the Main Base Plume regions. The maximum concentration of TCE within the largest of
the three individual plumes in the East Base Plume region is approximately 45 pg/L,
compared to 740 ug/L for the Main Base Plume. Additionally, the maximum TCE
concentrations within the smaller East Base Plumes are only slightly above MCL levels.  This
alternative represents a low cost option because of the limited efforts required for
implementation.

Natural intrinsic processes of biodegradation and adsorption may control the spread of the
plume. Although technically feasible, acceptance by community and regulatory agencies is
unlikely.

This alternative has an overall cost of approximately $0.5 million.  Factors which may affect
the cost of this alternative are well  maintenance and structural repairs of existing wells due to
deterioration over time.

3.7.2 Alternative 2: Impacted Area Well-Head Treatment/Well Destruction and
Monitor

Main Base Plume.  Under the Impacted Area Weil-Head Treatment alternative for the Main
Base Plume, action would be taken to provide acceptable quality water at impacted wells.
Individual well-head carbon treatment units, similar to those currently in place at five off-
base domestic wells, would be installed when future monitoring of domestic and municipal
production wells indicates that it is necessary. In addition, administrative restrictions would
be instituted to prevent installation of new production wells in impacted areas or areas with
the potential to be impacted.

The  treatment process options incorporated into this alternative include intrinsic
biodegradation, GAC treatment units at individual domestic well-heads, and similar, larger
scale, GAC units at the single municipal well effected.

The  individual treatment units would be designed to reduce TCE concentrations in water to
the detection limit (0.5 fig/L). Other COCs would be similarly removed. A 16-gpm capacity
carbon treatment unit would be sufficient for each of the domestic wells. It was assumed that
four carbon treatment units, each with a capacity of 500 gpm, would be used in parallel to
treat each municipal well.

The CB-Part 1 RI/FS identifies vertical conduits and downgradient receptor wells,
respectively, that may be affected in the future by the migrating TCE plume. Based on an
analysis of factors including proximity to the TCE plume, well construction, existing
subsurface lithology, and localized hydraulic gradients, it was estimated that a total of 26
domestic wells and one municipal  well would require well-head treatment. In addition, seven
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domestic wells, one irrigation well, and one production well would be sealed because the
wells may have been screened across more than one HSZ, and may thus serve as conduits for
contamination.

Individual well-head treatment units have been effective in reducing the concentrations of
contaminants in ground water pumped from production wells to levels below MCLs;
however, this alternative does not include measures to prevent the migration of the
contaminated plumes.  A conservative assumption is that this alternative may not meet
PRAOs or prevent further migration of contaminant plumes. However, it was considered
protective of human health because it would address the toxicity and mobility of the
contaminated drinking water source prior to the point of exposure.

This alternative was found to be technically feasible and easily implementable because the
individual well-head carbon treatment units are commonly employed, and are based on
proven technology that has been used successfully for domestic well treatment in the past.
The domestic well-head treatment units currently in place consist of individual treatment
tanks containing one cubic foot of GAC.  According to the current Castle AFB domestic
well-head treatment maintenance contractor, they are typically backwashed monthly and can
last for up to two years without carbon replacement.

This alternative may also be considered feasible because well-head treatment units are
currently in place at five domestic wells in the Castle AFB area and appear to be acceptable
to the community. However, acceptance by community and regulatory agencies was believed
to be unlikely due to the potential for the contaminant plumes to continue spreading.

As with the No Action alternative, the 244 existing monitoring wells associated with the
Main Base Plume are assumed to be monitored for 30 years. In addition, twelve new
monitoring wells (including four in the shallow HSZ, two in the USS HSZ, three in the LSS
HSZ, and three in the CF HSZ) were proposed to further monitor plume migration. These
new monitoring wells were included in this alternative to further assess whether certain off-
base domestic, irrigation, and municipal wells would be impacted by the TCE plume. The
new monitoring wells would be placed between the plume and the potential receptor wells.
Additional sampling for contaminants would also be conducted at the potential receptor
wells.

This alternative was considered to be cost-effective with a total present worth estimated to be
approximately $ 12 million.  Of the 27 potentially impacted wells assumed in the cost
estimate to require the installation of well-head treatment units, only one is a production well
requiring the installation of 500-gpm carbon units. A smaller 16-gpm unit, which costs
$ 1,400, would be sufficient for domestic wells.

East Base Plume.  The Well Destruction and Monitoring alternative for the East Base Plume
would mitigate the potential health risks  arising from the East Base Plume region by sealing

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existing wells that provide a conduit for the introduction of contaminants to the groundwater.
The potential impact of the East Base Plume has been identified through consideration of
receptor well location and construction, existing subsurface lithology, localized hydraulic
gradients, and current plume boundaries.  Based on this analysis, certain wells have been
identified as potential receptor wells which may be impacted by migration of the East Base
Plume beyond 30 years. Two of these wells (PW-5 and PW-1 IE) are currently out of service.
Production wells having the potential for HSZ cross contamination would be sealed and
abandoned (following appropriate guidelines) to avoid the potential spread of contamination.
This alternative would include 30 years of continued monitoring of the 44 existing
monitoring wells associated with the East Base Plume region.

Because no action would be taken to contain the contaminant plumes, this alternative may not
meet the PRAOs.

The Well Destruction and Monitoring alternative is considered  to be more easily
implemented for the East Base Plume region than is the Weil-Head Treatment alternative for
the Main Base Plume.

3.7.3 Alternative 3: Extraction with TCE Capture Objective of 5 ug/L

Main Base Plume. The 5 ug/L Capture alternative includes the design of a groundwater
extraction well network to effectively capture and minimize the spread of the TCE-
contaminated plume within four contaminated groundwater zones. The extraction wells
proposed would be designed and constructed according to State of California Department of
Health Services Technical Standards for the Design and Construction of Extraction Wells at
Hazardous Waste Sites. The extraction wells should capture and remove the plume of TCE
(and other COCs) dissolved in groundwater; however, anticipated plume capture volumes
may not be achieved due to subsurface geologic characterization.  In addition,  TCE adsorbed
onto soils may be partially immobilized and escape freatment; however, as the liquid-phase
TCE is removed, the adsorbed phase will gradually return into the liquid phase to maintain
equilibrium and will eventually enter the treatment system.

This alternative assumes that  12 new monitoring wells will be placed downgradient of the
plume to monitor plume movement and hydraulic conditions over the 15-year  operation
period.

This Main Base Plume alternative requires the following extraction well totals (including
those wells implemented under OU 1 and OU 2):

•   Nineteen extraction wells for the shallow HSZ with total extraction rate of 2,625 gpm
•   Twelve extraction wells for the upper subshallow HSZ with total extraction rate of 1,650
    gpm
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•  One well for the lower subshallow HSZ with an extraction rate of 200 gpm
•  Two wells for the confined HSZ with total extraction rate of 250 gpm

The following extraction wells are the new wells that would be included beyond those for OU
1 and OU 2:

•  Three new extraction wells for the shallow HSZ with a total extraction rate of 500 gpm
•  Seven new extraction wells for the upper subshallow HSZ with a total extraction rate of
   850 gpm
•  One new extraction well for the lower subshallow HSZ with an extraction rate of 200
   gpm
•  Two new extraction wells for the confined HSZ with a total extraction rate of 250 gpm

The extraction well numbers, design pumping rates and the initial TCE concentrations for the
5 ug/L Capture alternative are summarized in Table 3-9. Calculations based on the modeling
results indicate that with a cleanup criterion of 5 ug/L, the groundwater remediation time may
range from ten to 60 years, depending on the HSZ that is being remediated. The lower
subshallow HSZ has the longest remediation time period (60 years), the shallow HSZ is 20
years, the upper subshallow HSZ is 30 years, and the confined zone has the shortest (ten
years). The actual remediation time is dependent on how aggressively (fast) the groundwater
is extracted.

The 5 ug/L TCE Capture alternative is expected to be effective in removing TCE and other
COC contamination since both the lithology and types of contaminants identified at Castle
AFB are well suited to groundwater pump and treat technologies. However,  pump and treat
systems have been shown to have limited success in achieving remedial objectives within a
reasonable time period.  Operation of this remedial alternative to reduce organic contaminant
concentrations to MCLs will be protective of public health for potential uses of the
groundwater.

This alternative has the potential to meet the PRAOs for treatment of contaminated
groundwater to MCLs within eight to 60 years depending on  the HSZ. The cleanup period is
estimated based on data and assumptions presented in the CB-Part 1 RI and Appendix C of
the FS.

All four treatment options considered for this alternative are proven, effective technologies
capable of reducing TCE and other COC concentrations below detection limits.  Therefore,
this alternative appears to protect human health and the environment because it is expected to
reduce the toxicity, mobility, and volume of contamination.

The 5 ug/L TCE Capture alternative is technically feasible since the process options for
extraction, treatment, and disposal are proven, accepted, and  widely used.
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The preliminary range of the estimated present worth costs for the 5 ug/L TCE Capture
alternative is from $15 to $34 million, and is dependent on the process options selected for
treatment and disposal.  The estimated costs for this alternative were developed under the
assumption that the RA will operate for a period of 15 years.  This assumption was made for
the purpose of comparative analysis among the alternatives considered, although it is
recognized that RA will likely be necessary over a longer period of time. The extraction well
numbers, design pumping rates and the initial TCE concentrations for the 5 ug/L capture
alternative are summarized in Table 3-9.  Calculations based on the modeling results indicate
that with a cleanup criterion of 5 ug/L, the groundwater remediation time may range from
eight to 60 years, depending on the HSZ that is being remediated.  The LSS HSZ has the
longest remediation time period (60 years).

The AF is committed to completion of the RA regardless of the  required time period of
remediation. The actual costs to construct and operate the groundwater extraction system to
achieve the 5 ug/L TCE cleanup objectives are likely to be significantly higher than the costs
presented.

East Base Plume. The 5 ug/L TCE Capture alternative includes an extraction system
designed to meet the PRAOs for the East Base Plume region of capturing all groundwater
with TCE concentrations exceeding the MCL. The same treatment options considered for the
Main Base Plume regions would be considered for this alternative; for groundwater disposal,
only reinjection was considered. This was due to the limited number of injection wells
required  and the distance of the  proposed treatment plant location from an existing irrigation
canal.  In addition, because the extraction and injection wells proposed for the East Base
Plume region would be  screened only within the shallow HSZ, the potential implementation
difficulties associated with injection of water derived from multiple HSZs does not arise for
this alternative.

The overall effectiveness of this alternative, including the  treatment and disposal options, is
considered good since it will meet the PRAOs and protect public health by reducing the TCE
concentrations in groundwater to MCL. The alternative is technically implementable because
the extraction, treatment, and disposal technologies are proven and a limited number of
extraction and injection wells are required. This alternative may be more acceptable to the
regulatory agencies and the public than the similar alternative for the Main Base Plume
regions due to the smaller plume volume, lower average TCE concentrations, and reduced
potential for impact to receptor  wells for the East Base Plume region.  The present worth cost
range for this alternative is $4 to $6 million (depending on the treatment option).

This capture alternative requires two extraction wells for the shallow HSZ (with total
extraction rate of 325 gpm). Calculations based on modeling results indicate that with  a
cleanup criterion of 5 ug/L, the  groundwater remediation time may range from eight to 60
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years. The actual remediation time is dependent on how aggressively (fast) the groundwater
is extracted.

3.7.4 Alternative 4: Extraction with TCE Capture Objective of 0.5 ug/L
Main Base Plume.  The 0.5 ug/L TCE Capture alternative includes an extraction system and
various treatment and disposal options designed to capture groundwater with any detectable
TCE above 0.5 Mg/L. The rationale for the development of the 0.5 ug/L Capture alternative
is similar to that for the 5 pg/L Capture alternative. The primary distinction between the two
alternatives is the much greater volume of groundwater requiring extraction and treatment,
and the associated higher cost.

As with the 5 ug/L Capture alternative, the 0.5 ug/L Capture alternative includes the design
of a groundwater extraction well network that would effectively capture and prevent the
spread of the TCE-contaminant plume within four contaminated groundwater zones, but to  a
lower residual limit. In addition, this alternative assumes that  12 new monitoring wells will
be placed downgradient of the plume to monitor plume movement  and hydraulic conditions
over the 15-year operation period.

This alternative would require the following wells:

•  Twenty-two extraction wells for the shallow HSZ with total extraction rate of 3,225 gpm
•  Fourteen extraction wells for the upper subshallow HSZ with total extraction rate of
   2,000 gpm
•  Three extraction wells for the lower subshallow HSZ with total extraction rate of 400
   gpm
•  Three extraction wells for the confined HSZ with total extraction rate of 450 gpm

The  extraction wells that would be included in addition to those for OU 1 and OU 2 are as
follows:

•  Seven extraction wells for the shallow HSZ with a total extraction rate of 1,100 gpm
•  Nine extraction wells for the upper subshallow HSZ with a total extraction rate  of 1,200
   gpm
•  Three extraction wells for the lower subshallow HSZ with a total extraction rate of 400
   gpm
•  Three extraction wells for the CF HSZ with a total extraction rate of 450 gpm

This alternative has the potential to reduce concentrations of TCE within  groundwater to the
0.5 mg/L detection limit within 18 to 170 years depending on the HSZ. The actual
remediation time is dependent on how aggressively (fast) the groundwater is extracted.  If the
proposed cleanup objective of 0.5 ug/L can be achieved, this alternative would be effective in
restoring groundwater in the Main Base Plume regions to near background conditions.
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The 0.5 ug/L TCE Capture alternative is technically more difficult to implement than the 5
ug/L and the 3 ug/L Capture alternatives, primarily because the 0.5 ng/L Capture alternative
would require the installation of a greater number of extraction and injection wells over a
larger area and their operation over a longer period of time. In addition, the presence of the
geophysical and geochemical conditions discussed previously are likely to make this remedial
alternative technically impractical. This alternative should be acceptable to the regulatory
agencies and the public since it attempts to restore groundwater quality to background levels.

The expected overall present worth costs for the 0.5 ug/L Capture alternative range from
approximately $25 to $53 million, depending on the process options selected for treatment
and disposal. The estimated costs for this alternative were developed under the  assumption
that the RA will operate for a period of 15 years.  The reasoning for this assumption is that
typically, groundwater extraction actions will be reevaluated within 15 years to assess if
continued operation is likely to result in achieving the RA objectives within a reasonable time
period.  However, the estimated time predicted to achieve the cleanup objectives for this
alternative may be as long as 170 years. Thus, the actual costs to construct and operate the
groundwater extraction system to achieve the 0.5 [ig/L TCE-cleanup objectives are likely to
be significantly higher than  the costs presented.

This alternative is more costly than the 5 ug/L Capture alternative because it would capture
and treat a much larger volume of groundwater, although the total mass of TCE that would be
removed is only 8 percent more.  Changing the cleanup objective from the MCL to the
detection limit would increase costs by 50 to 60 percent.

East Base Plume. The 0.5  ug/L TCE Capture alternative includes an extraction system
designed to capture all groundwater with TCE concentrations exceeding the detection limit.
The same treatment and disposal options considered for the 5 ug/L TCE alternative were
considered for this alternative.

The overall effectiveness of this alternative, including the treatment and disposal options is
considered good since it will meet the PRAOs and reduce'TCE and other COC
concentrations in  groundwater to near background level.  As discussed previously, the
technical feasibility of meeting a cleanup objective near the detection limit for TCE in
groundwater is not considered good. The alternative is technically implementable because
the extraction, treatment, and disposal technologies are proven and a limited number of
extraction and injection wells are required. This alternative should be acceptable to the
regulatory agencies and the public since it attempts to restore groundwater quality to
background levels.  The present worth cost range for this alternative is $6 to $8  million
(depending on the treatment option). The estimated costs for this alternative were developed
under the assumption that the RA would operate for a period of 15 years.
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This alternative would require two extraction wells for the shallow HSZ with total extraction
rate of 350 gpm.

The extraction well numbers, design pumping rates and the initial TCE concentrations for the
0.5 ug/L Capture alternative are summarized in Table 3-12.  This alternative has the potential
to reduce concentrations of TCE within groundwater to the 0.5 detection limit within 20 to 90
years. The actual remediation time is dependent on how aggressively (fast) the groundwater
is extracted.  If the proposed cleanup objective of 0.5 ug/L can be achieved, this alternative
would be effective in restoring groundwater in the East Plume regions to near background
conditions.

3.7.5  Alternative 5: Extraction with TCE Capture Objective of 3 ug/L

Main Base Plume. The 3 ug/L TCE Capture alternative includes an extraction system along
with various treatment and disposal options designed to capture all groundwater with TCE
concentrations exceeding  3 ug/L.  The rationale for the development of the 3 ug/L TCE
Capture alternative is similar to those for the 5 ug/L and 0.5 ug/L Capture alternatives.
However, this alternative has a lower residual limit than 5 ug/L (Alternative 3) and a higher
residual limit than 0.5 ug/L (Alternative 5).

As with the other fapture alternatives, the 3 ug/L Capture alternative includes the design of a
groundwater extraction well network that would effectively capture and prevent the spread of
the TCE-contaminant plume within four contaminated groundwater zones. In addition, this
alternative assumes that 12 new monitoring wells will be placed downgradient of the plume
to monitor plume movement and hydraulic conditions over the 15-year operation period.

This capture alternative would require the following wells:

•  Twenty-two extraction wells for the shallow HSZ with total extraction rate of 2,875 gpm
•  Thirteen extraction wells for the upper subshallow HSZ with total extraction rate of 1,600
   gpm
•  Two extraction wells for the lower subshallow HSZ with total extraction rate of 280 gpm
•  Two extraction wells for the confined HSZ with total extraction rate of 320 gpm

The  extraction wells that would be included in addition to those for OU 1 and OU 2 are as
follows:

•  Six extraction wells for the shallow HSZ with a total extraction rate of 750 gpm
•  Nine extraction wells for the upper subshallow HSZ with a total extraction rate of 1,000
   gpm
•  Two extraction wells for the lower subshallow HSZ with a total extraction rate of 280
   gpm
•  Two extraction wells for the confined HSZ with a total extraction rate of 320 gpm

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The extraction well numbers, design pumping rates and the initial TCE concentrations for the
3 pg/L capture alternative are provided in Table 3-10.

This alternative has the potential to reduce concentrations of TCE within groundwater to less
than 3 pg/L within 10 to 150 years, depending on the HSZ. This cleanup period is estimated
by interpolating the model results for the 5 pg/L and 0.5 ug/L Capture alternatives. The
actual remediation time is dependent on how aggressively (fast) the groundwater is extracted.
If the proposed cleanup objective of 3 ug/L can be achieved, this alternative would result in a
marginal increase in reduction of risk over the 5 ug/L alternative, while significantly
increasing the cost and time required for cleanup.

The 3 ug/L Capture alternative is technically more difficult that the 5 ug/L Capture
alternative, but less difficult technically than the 0.5 pg/L Capture alternative because it
requires an intermediate number of extraction and injection wells.

The overall present worth costs for the 3 ug/L Capture alternative range from $19 to $41
million.  The estimated costs for this alternative were developed under the assumption that
the RA will operate for a period of 15 years.  The reasoning for this assumption is that
typically groundwater extraction actions will be reevaluated within 15 years to assess if
continued operation is likely to result in achieving the RA objectives within a reasonable time
period.  However, the estimated time predicted to achieve the cleanup objectives for this
alternative may be as long as 150 years. Thus, the actual costs to construct and operate the
groundwater extraction system to achieve the 3 pg/L TCE-cleanup objectives are likely to be
significantly higher than the costs presented. This alternative represents a cost level between
those of the 5 pg/L and 0.5 ug/L Capture alternatives.

East Base Plume. The 3 ug/L TCE Capture alternative includes an extraction system
designed to capture all groundwater with TCE concentrations exceeding 3 ug/L TCE.  The
same treatment and disposal options considered for the 5 pg/L TCE alternative are
considered for this alternative.

The overall effectiveness of this alternative, including the treatment and disposal options is
considered good since it will meet the PRAOs. The technical feasibility of achieving the
cleanup objective of 3 pg/L TCE concentration in groundwater is intermediate between the
feasibility for the 5 pg/L and 0.5 pg/L objectives. The alternative is technically
implementable because the extraction, treatment, and disposal technologies are proven and a
limited number of extraction and injection wells are required.  The estimated present worth
cost range for this alternative is $4 to $6 million (depending on the treatment option).  The
estimated costs for this alternative were developed under the assumption that the RA would
operate for a period of 15 years.
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This capture alternative would require two extraction wells for the shallow HSZ with a total
extraction rate of 325 gpm. In addition, three injections wells would be required to be
installed in the shallow HSZ.  The extraction well numbers, design pumping rates and the
initial TCE concentrations for the 3 ug/L Capture alternative are summarized in Table 3-11.
This alternative has the potential to reduce concentrations of TCE within groundwater to 3
ug/L within 10 to 80 years. The actual remediation time is dependent on how aggressively
(fast) the groundwater is extracted.

3.7.6  Alternative 6: Extraction for Plume Control Combined with Potential Weil-Head
Treatment

Main Base Plume. The Plume Control alternative includes an extraction system and various
treatment and disposal options designed to control  the spread of TCE and other COCs from
the shallow groundwater zones to the confined groundwater zone and to provide well-head
treatment for any domestic wells impacted by TCE-plume migration, if necessary. This
alternative applies to the Main Base Plume regions only.

The Plume Control alternative would be a phased approach which builds on existing
groundwater cleanup operations and plans.  It includes the completion of planned OU  1
upgrades, and the expansion of the completed construction of OU 2 to mitigate and control
the vertical and horizontal migration of the plumes. The analytical results from the LTGSP
will be monitored and analyzed to determine the location, extension, and any movement of
the plume. The plume would be characterized in terms of a 5 ug/L TCE contour line.
Furthermore, well-head treatment would be implemented if needed to protect domestic and/or
irrigation wells, but would not serve as a primary RA.

The objectives of the Plume Control alternative are to control the plumes  in each
groundwater zone to their current areas; to mitigate and restrict the vertical migration of the
contaminants; and to remove the contaminants cost-effectively. This alternative would
continue until the discontinuation of the pump and treat systems would not result in a short-
term significant expansion or movement of the plume (5 ug/L contour) and natural
attenuation would be relied upon for further reduction. In addition, this alternative will be
accomplished by implementing a treatment system standard of 0.5 ug/L TCE.

This alternative also includes the abandonment and closure of the seven domestic wells, one
irrigation well, and one production well which are  contaminated and are screened across
multiple groundwater zones and have the potential to act as vertical conduits to allow the
vertical migration of TCE and other COCs. In addition, similar to the other extraction
alternatives, 12 new monitoring wells will be placed downgradient of the plume to monitor
the plume migration and hydraulic conditions over the expected 15 years  that this remedial
alternative would be in operation.
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The Plume Control alternative for the Main Base Plume regions would require the following
wells:

•   Nineteen extraction wells for the shallow HSZ with a total extraction rate of 2,325 gpm
•   Four extraction wells for the upper subshallow HSZ with a total extraction rate of 600
    gpm
•   Five extraction wells for the lower subshallow HSZ with a total extraction rate of 1,000
    gpm

The extraction wells that would be included in addition to those for the OU 1 and OU 2 are as
follows:

•   Three new extraction wells in the Main Base Plume regions  shallow HSZ with a total
    extraction rate of 200 gpm
•   Five new extraction wells in the Main Base Plume regions lower subshallow HSZ with a
    total extraction rate of 1,000 gpm

The extraction well numbers, design pumping rates and the initial TCE concentrations for the
Plume Control alternative are summarized in Table 3-12.

This alternative is expected to be effective in removing TCE and other COCs and controlling
TCE-plume migration, since both the subsurface lithology and types of contaminants present
at Castle AFB are well suited to groundwater pump and  treat technologies. Though pump
and treat systems have been shown to have limited success in achieving the remedial
objectives within a reasonable time period, this alternative is different from the other pump
and treat alternatives since its primary objective is to control vertical TCE plume migration to
the confined HSZ rather than meet a TCE-cleanup objective. Based on the analysis of the
two-dimensional modeling results, this alternative is expected to be very effective in
achieving its primary objective of mitigating the vertical migration of TCE to the confined
HSZ. However, this alternative may not achieve the objective of remediating the TCE plume
to meet the PRAOs.

The Plume Control alternative is technically feasible since the process options for extraction,
treatment, and disposal of groundwater are proven, accepted, and widely used.  In addition,
the impacted well-head carbon treatment units are commonly employed, and are also based
on proven technology that has been used successfully for domestic well treatment in the past.
The administrative feasibility is expected to be good because well-head treatment units are
currently in place at five domestic wells and appear to be acceptable to the community, and
because the potentially impacted municipal production well will be protected from TCE
plume migration. In addition, there will be reduction in the mobility, toxicity, and volume of
contamination. There may be opposition from some of the public and regulatory agencies
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concerned about the possible inability of this alternative to meet TCE and other COC cleanup
objectives.

The preliminary range of the estimated present worth costs for the Plume Control alternative
is from $12 to $21 million, and is dependent on the process options selected for treatment and
disposal. The estimated costs for this alternative were developed under the assumption that
the RA will operate for a period of 15 years. The reasoning for this assumption is that
typically groundwater extraction action will be reevaluated within 15 years to assess its
effectiveness in achieving desired objectives. There is a possibility that the operation will
need to extend beyond the 15-year period, so actual costs may be higher than the costs
presented in this FS^. This alternative is expected to be significantly more cost-effective than
the groundwater pump and treat alternatives designed to meet cleanup objectives because of
the lower volume of groundwater requiring treatment.

3.8    DETAILED AND COMPARATIVE ANALYSES OF REMEDIAL
       ALTERNATIVES

This section presents a comparative analysis of the remedial alternatives based on CERCLA
criteria (EPA, 1988a) for the Main Base Plume and the East Base Plume regions.

The comparative analysis of alternatives for the Main Base Plume regions and for the East
Base Plume regions are presented separately. Summaries of these analyses are presented in
Tables 3-16 and 3-17. Each of the remedial alternatives is compared against seven of the
nine CERCLA criteria:  1) Overall Protection of Human Health and the Environment, 2)
ARARs, 3) Long-Term Effectiveness and Permanence, 4) Reduction of Toxicity, Mobility
and Volume through Treatment, 5) Short-Term Effectiveness, 6) Implementability, and 7)
Cost. The modifying criteria, 8) State/Support Agency acceptance and 9) Community
Acceptance, have also been considered in the selection of remedies, and are discussed in
Sections 3.8.3.1 (Main Base Plume) and 3.8.3.2 (East Base Plume).

Each remedial alternative was scored using a range of 1 to 5 for each of the seven evaluation
criteria. The basis for scoring each  criterion is detailed below:

Overall Protection of Human Health and the Environment: Evaluation according to this
criterion provides an overall assessment of how adequately the alternative eliminates risks to
human health and the environment. A score of 1 indicates that the remedial alternative would
provide an unacceptable level of protection for human health and the environment. A score
of 5 indicates that die COCs would be captured and treated to meet the PRAOs. Scores of 2,
3, and 4 were assigned on a relative basis to account for qualitative differences among
remedial alternatives that do not warrant a score of 1  or 5.

ARARs:  A score of 1 indicates that the remedial alternative would fail to satisfy ARARs,
and a score of 5 indicates that the alternative would satisfy all ARARs.  A score of 2, 3, or 4

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was assigned to those remedial alternatives that would possibly meet all ARARs or would be
eligible for one or more of the statutory waiver conditions for an ARAR.

Long-Term Effectiveness and Permanence: Evaluation of alternatives under this criterion
addresses the risks posed after the alternative response objectives have been met This
evaluation considers the magnitude of residual risk remaining after completion of the
alternative and the adequacy and reliability of controls, if any, that are used to manage
untreated contaminants at the site. A score of 1 indicates that no reduction in potential risk
would be achieved.  A score of 5 indicates that no unacceptable potential risk remains after
the response objectives have been met. Scores of 2,3 and 4 were assigned on a relative basis,
taking into account differences in the site conditions after response objectives have beerrmet.

Reduction of Toxicity, Mobility, and Volume Through Treatment: This evaluation
criterion addresses the preference for alternatives that permanently and significantly reduce
the toxicity, mobility, or volume of the hazardous substances. A score of 1 indicates that the
remedial alternative would not reduce the toxicity, mobility, or volume of contamination at
the site. A score of 5 was assigned  when the reduction in toxicity, mobility, and volume of
contamination would be sufficient to restore the site to near background conditions. Scores
of 2, 3, and 4 were assigned on a relative basis to account for qualitative differences between
remedial alternatives that do not warrant a score of 1  or 5.

Short-Term Effectiveness: This evaluation criterion addresses human health and
environmental risks arising from implementation of the remedial alternative. The factors
considered include protection of workers and the surrounding community, environmental
impact, and the length of time required to meet the response objectives. A score of 1  was
assigned if the actions to implement the alternative will produce unacceptable health or
environmental impacts and the actions will take an unacceptable time to complete. A score
of 5 was assigned if the actions to implement the alternative will produce no significant
unacceptable health or environmental impacts and wet actions can be completed in a short
time.  Scores of 2,3, and 4 were assigned on a relative basis to account for qualitative
differences between alternatives that do not warrant a score of 1 or 5.

Implementability: This criterion addresses the technical and administrative feasibility of
implementing an alternative. Technical feasibility factors include the availability and reliability
of equipment and services required to implement the alternative. Administrative feasibility
addresses factors such as anticipated difficulties in obtaining access to off-site locations. A
score of 1 indicates that significant uncertainty would exist as to the reliability or availability of
equipment or services required, or that significant difficulty is anticipated in obtaining required
access. A score of 5 indicates that all equipment and services required are proven reliable and
are readily available, and that no problems are anticipated in obtaining access. Scores of 2,3,
and 4 were assigned on a relative basis to account for qualitative differences between remedial
alternatives that do not warrant a score of 1 or 5.
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Cost: Scores are assigned on a relative scale based on the range between zero cost and the
most expensive alternative.  A score of 5 indicates costs between 0 and 20 percent of the cost
of the most expensive alternative; a score of 4 indicates relative costs between 21 and 40
percent; a score of 3 indicates relative costs between 41 and 60 percent; a score of 2 indicates
relative costs between 61 and 80 percent; and a score of 1 indicates relative costs between 81
and 100 percent of the most expensive alternative.

The scores in Table 3-13 indicate that the alternatives for the Main Base Plume regions differ
significantly in environmental protection and cost. The alternatives emphasizing institutional
responses generally cost less, but the alternatives including groundwater remediation provide
more environmental protection. Similarly, as indicated in Table 3-14, cost differences
between the alternatives considered for the East Base Plume region are significant. However,
the alternatives including only institutional responses provide nearly as much environmental
protection as the alternatives including groundwater remediation.

Costs for the Main Base Plume alternatives are summarized in Table 3-15 and costs for the
East Base Plume alternatives are summarized in Table 3-16. Detailed cost analyses of the
alternatives are presented in Appendix D of the FS.

3.8.1  Main Base Plume Regions. The shallow and USS HSZs within the Main Base Plume
regions contain the bulk of the TCE present in the groundwater beneath Castle AFB. The
comparative analysis for the Main Base Plume regions considers only the contamination  that
is outside of the capture zones for the OU 1 and OU 2 systems. About 50 percent (3,000
pounds) of the mass of TCE in the Main Base Plume regions is outside of the capture zones
for the OU 1 and OU 2 systems.

The following summary of the comparative analysis of the alternatives for the Main Base
Plume regions is structured by the seven evaluation criteria. Under the heading of each of the
criteria, the performance of the six alternatives is discussed in descending order from the
highest to lowest performance.

3.8.1.1 Overall Protection of Human Health and the Environment. With the exception
of the No Action alternative, all of the remedial alternatives considered for the Main Base
Plume regions provide some degree of protection of human health and the environment.

The 5 ng/L TCE Capture alternative, 0.5 ug/L TCE Capture alternative, and 3 ng/L TCE
Capture alternative provide capture and treatment of the contaminants  to the MCL or more
stringent standards and each has been assigned a score of 5 for all process options.

The Plume Control alternative removes contaminant mass from the shallow, upper
subshallow, and lower subshallow HSZs and controls plume migration in these HSZs. The
modeling of TCE transport in the confined HSZ for this alternative (CB-Part 1 FS Appendix

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C) indicates that existing municipal wells will be protected. Individual well-head treatment
units would be installed on any impacted domestic wells. However, this alternative provides
less overall environmental protection than the extraction alternatives that would capture and
clean up the concentrations of COCs in groundwater to MCL standards. Therefore, this
alternative was assigned a score of 4 for all process options.

Alternative 2, Impacted Area Weil-Head Treatment may not prevent the Main Base Plume
from reaching domestic wells, but it will remove contaminants from the water before it is
used.  This  alternative, however, provides  less overall environmental protection than
alternatives that will capture and clean up COCs in groundwater to MCL standards, and has
therefore been assigned a score of 3.

The No Action alternative will potentially expose users of specific water supply wells to
significant ingestion and dermal contact should the Main Base Plume be tapped by their
wells. The No Action alternative therefore provides an unacceptable level of protection and
was assigned a score of 1.

3.8.1.2 Compliance with Applicable or Relevant and Appropriate Requirements .
Tables 3-17 and 3-18 are tables that summarize the RI/FS analysis of alternatives for the
Main and East Base Plumes with respect to federal and State of California ARARs. Section
4 provides detailed information regarding ARARs governing groundwater cleanup at Castle
AFB.

The AF has determined, with concurrence of the EPA and the State of California, that the 5.0
ug/L TCE Capture alternative complies with State Water Resources Control Board
(SWRCB) Resolution 92-49. This is based on a cost/benefit analysis, public comments on
the Proposed Plan, and state review. The benefit to remediate to 0.5 ug/L and 3  ug/L
concentrations is determined not to be cost-effective for the additional benefit derived.
Therefore, the 5.0 ug/L TCE Capture alternative meets all chemical- and action-specific
ARARs.

The Well-Head Treatment alternative is not expected to comply with state groundwater - ••
protection standards. The Weil-Head Treatment alternative was therefore assigned a score of
2, indicating that the proposed remedial alternative fails to satisfy some of the ARARs.

3.8.13 Long-Term Effectiveness and Permanence. The 5 ng/L, 3 jig/L, and 0.5 ng/L TCE
Capture alternatives will capture and clean up the Main Base Plume to MCLs or lower
concentrations, and will leave no significant potential health or environmental risks,
therefore, these alternatives were^assigned a score of 5 for all process options.

The Plume Control alternative will capture and  remove most of the contaminant mass from
the shallow, upper subshallow, and lower subshallow HSZs that is not within the capture
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zones of the OU 1 or OU 2 systems. This would allow natural attenuation to mitigate the
remaining contamination in these HSZs as well as the confined HSZ. Installation of
individual well-head treatment units at any impacted receptor wells would mitigate the
potential health impacts from use of groundwater in areas containing concentrations of COCs
above MCLs. Therefore, this alternative was assigned a score of 4 for all process options.

Although the Impacted Area Weil-Head Treatment alternative would not reduce the extent of
groundwater contamination, the installation of individual treatment units at receptor wells
will mitigate the potential health impacts from use of groundwater impacted by the
contamination.  Therefore, this alternative was assigned a score of 2.

The No Action alternative would not reduce the extent of groundwater contamination, aside
from any natural attenuation, and no measures would be taken to prevent human exposure or
further degradation of the environment. Therefore, the No Action alternative was assigned a
score of 1.

3.8.1.4  Reduction of Mobility, Toxicity, or Volume. The 0.5  ug/L TCE Capture
alternative would capture and clean up the plume to near background conditions, achieving
significant reductions in plume toxicity, mobility, or volume. Except for air stripping, which
would transfer the contaminants to the atmosphere, the associated treatment technologies
would directly (UV/oxidation) or indirectly (thermal reactivation of spent GAQ permanently
destroy the contaminants. Therefore, while Alternatives 4B, 4C, and 4D were assigned a
score of 5, Alternative 4A was assigned a score of 4.

The volumes of the 5 ug/L and 3 ug/L TCE plumes  are 54 percent and 69 percent,
respectively, of the volume of the 0.5 ug/L TCE plume. However, the associated masses of
these plumes are 92 and 94 percent, respectively, of the mass of TCE for the 0.5 ug/L plume.
Therefore, the 5 ug/L and 3 ug/L TCE Capture alternatives were assigned a score of 4 for all
process options with the exception of the air stripping with canal discharge, which was
assigned a score of 3.

No computer modeling was conducted to predict the capture zone for the Plume Control
alternative. However, by considering the number of extraction wells, well locations, and total
extraction rates, it is estimated that this alternative will capture and remove at least 70 percent
of the volume and mass associated with the 0.5 fig/L TCE Capture alternative. Therefore, the
Plume Control alternative was assigned a score of 3 for all process options.

The Impacted Area Weil-Head Treatment alternative would not reduce the volume or
mobility of contaminants, but would address potential toxicity to end-users at individual
wells.  Therefore; this alternative was assigned a score of 2.
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The No Action alternative would not, aside from natural attenuation, produce any reduction
in the volume, mobility, or toxicity of the Main Base Plume. Therefore, No Action was
assigned a score of 1.

3.8.1.5 Short-Term Effectiveness. The No Action alternative does not pose any risk to
workers or the public since no actions are taken and this alternative requires no time to
complete. Therefore, the No Action alternative is assigned a score of 5.

The Plume Control alternative would require installation of fewer wells and trenches than any
of the three TCE Capture alternatives. This alternative is also much more likely to achieve its
objectives in a reasonable length of time. Therefore, the Plume Control alternative was
assigned a score of 4 for all process options.

The Impacted Area Well-Head Treatment alternative poses little risk to workers or the public
and the time required to implement this alternative is short. However, workers would have
some potential for exposure to contaminants during installation of the well-head treatment
units, therefore, this alternative was assigned a score of 4.

More significant worker exposure may occur during implementation of the extraction
alternatives; especially during construction of extraction and injection wells and trenching for
installation of conveyance piping.  The air stripper process option may pose a slight risk due
to the emission of VOCs to the atmosphere. However, the risk posed by a properly designed
and operated air stripper should be negligible.  The primary differences among the 5 Mg/L, 3
Hg/L, and 0.5 ug/L TCE Capture alternatives are the increase in potential for worker
exposure as the capture objective is made more stringent due to the increased number of
wells and amount of trenching required, and the increased time required to complete the RA.
Therefore,jorjLn processoptions. the 5 ug/LTCE Capture; alternative.was. assigned a score
of 4. the 3 ug/L TCE Capture alternative was assigned a score of 3, and the 0.5 ug/L TCE
Capture alternative was assigned a score of 2.

3.8.1.6 Implementability. No technical or administrative difficulties are anticipated for the
No Action alternative, therefore, it was assigned a score of 5. The Impacted Area Well-Head
Treatment alternative poses no technical problems in implementation. However, permission
must be obtained from all public and private well owners before the well-head treatment units
can be installed and operated. Therefore, this alternative was assigned a score of 4.

The ground water extraction alternatives all utilize proven technologies for ground water
extraction, treatment, and disposal. Given the extent of the TCE plumes in the Main Base
Plume regions and the complex site geology, the AF is concerned that it could be technically
impractical and cost prohibitive to capture and clean up to the MCL or lower levels.  The
uncertainty of ever achieving the cleanup objective increases as the cleanup objective is made
more stringent. The injection disposal option may be difficult to implement, particularly if
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the differences in inorganic chemical concentrations among HSZs create technical problems.
The scoring of the extraction alternatives considered these various factors. The scores
assigned to the options for each of the four groundwater extraction alternatives were:

•  Plume Control alternative: option 6A, score 3; option 6B, score 4; option 6C, score 3;
   option 6D, score 3.

•  5 ng/L TCE Capture alternative: option 3A, score 2; option 3B, score 3; option 3C, score
   2; option 3D, score 2.

•  3 pg/L TCE Capture alternative: option 5A, score 2; option 5B, score 3; option 5C, score
   2; and option 5D, score 2.

•  0.5 ng/L TCE Capture alternative:  option 4A, score 1; option 4B, score 2; option 4C,
   score 1; and option 4D, score 1.

3.8.1.7  Cost. Cost comparisons of the alternatives for the Main Base Plume regions are
presented in Table 3-15 and in the summary below.  No Action has the lowest cost of all
alternatives, as the cost of continued groundwater monitoring is all that is included; score 5.

The highest-cost alternative is the.0.5 ug/L TCE Capture alternative with UV/oxidation
treatment and disposal by injection.  The estimated costs for the 5, 3, and 0.5 u,g/L TCE
Capture alternatives were developed under the assumption that the RA will operate for a
period of 15 years.  The costs of achieving these cleanup objectives may be affected because
of technical impracticability.  The actual costs for cleanup to these concentrations would thus
be much higher than the costs presented in this FS. Scores were assigned to each of the
alternatives according to the relative-cost method described at the beginning of this section.
Alternative
No Action

Impacted Area Well-Head Treatment

The 5 pg/L TCE Capture Alternative
(a) Air Stripping with Canal Discharge
(b) L-P GAC with Canal Discharge
(c) UV/Oxidation with Injection
(d) L-P GAC with Injection

The 0.5 ng/L TCE Capture Alternative
(a) Air Stripping with Canal Discharge
(b) L-P GAC with Canal Discharge
Cost($M)
. 2.9

2.9


15.7
22.9
34.5
33.4


25.9
38.4
Score
5

5


4
3
2
2


3
2
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Alternative
(c) UV/Oxidation with Injection
(d) L-P GAG with Injection
The 3 Mg/L TCE Capture Alternative
(a) Air Stripping with Canal Discharge
(b) L-P GAC with Canal Discharge
(c) UV/Oxidation with Injection
(d) L-P GAC with Injection

The Plume Control Alternative
(a) Air Stripping with Canal Discharge
(b) L-P GAC with Canal Discharge
(c) UV/Oxidation with Injection
(d) L-P GAC with Injection
Cost($M)
53.1
51.2

19.8
28.7
41.3
40.0


12.4
17.7
21.8
21.0
Score
1
1

4
3
2
2


4
4
3
4
3.8.2 East Base Plume Region. The East Base Plumes, which are confined to the shallow
HSZ, contain approximately 116 pounds of TCE, or less than 5 percent of the TCE estimated
to be outside of the capture zones for the OU 1 and OU 2 remedial systems.

In general, the alternatives for the East Base Plumes, including institutional responses,
received scores (based on the seven CERCLA criteria) similar to those received by the same
alternatives for the Main Base Plume regions. However, there are some differences because
the East Base Plume region is much smaller, contains less TCE, and has a lower potential for
impacting production wells. In addition, contamination in the East Base Plume region only
occurs in the shallow HSZ.

As with the comparative analysis of the alternatives for the Main Base Plume regions, each of
the remedial alternatives is compared against seven of the nine CERCLA criteria:  1) Overall
Protection of Human Health and the Environment, 2) ARARs, 3) Long-Term Effectiveness
and Permanence, 4) Reduction of Toxicity, Mobility and Volume through Treatment, 5)
Short-Term Effectiveness, 6) Implementability, and 7) Cost. The modifying criteria, 8)  *-
State/Support Agency Acceptance, and 9) Community Acceptance have also been considered
in the remedy selection process and are discussed in Section 3.8.3.2.  Under the heading of
each of the criteria, the performance of the five alternatives is discussed in descending order
from highest to lowest performance.

3.8.2.1 Overall Protection of Human Health and the Environment All of the
groundwater extraction and treatment alternatives provide capture and treatment to MCL
standards (or more stringent levels), and have therefore been assigned a score of 5 for all
process options.
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The primary health concern raised by these plumes is that the TCE they contain may be
drawn into nearby Castle AFB production wells.  Because these wells are screened across the
shallow and USS HSZs, they could act as potential vertical conduits for the transfer of
contaminants from the shallow to the deeper HSZs. For this reason, these wells are proposed
for destruction under the Impacted Area Well Destruction and Monitoring alternative.  The
East Base Plume region is characterized by much lower TCE mass and concentrations than
the Main Base Plume. Following a review of potentially impacted wells, it was assumed that
if the  production wells identified as having the potential for cross contamination are
destroyed, no other wells will require well-head treatment Should any receptor wells be
impacted in the future, well-head treatment would provide adequate protection for end-users.
For these reasons this alternative was assigned-a score of 4.                 • 3

The No Action alternative may not fully protect human health and the environment, since it
takes  no action to address the existing plume of contamination or potential future impact on
water supply wells. For this reason, the No Action alternative was assigned a score of 1.

3.8.2.2  Compliance with Applicable or Relevant and Appropriate Requirements. The
East Base Plume was analyzed against federal and State of California ARARs in the RI/FS
and the results of this analysis is summarized in Table 3-18.  Section 4 provides detailed
information regarding ARARs governing groundwater cleanup at Castle AFB.

The AF, with concurrence of the EPA and the state, has decided that active remediation of
the East Base Plume is not warranted at this time because removing these contaminants at
these  low concentrations gives little benefit compared to the high cost and because the
aquifer cleanup levels are expected to be reached in a reasonable period of time with the
selected Well Destruction and Monitoring alternative. Though some concentrations in the
East Base Plume exceed the cleanup levels, the Well Destruction and Monitoring alternative
is expected to be able to meet these aquifer cleanup levels in a reasonable period of time and
therefore comply with ARARs. This is based on monitoring data showing an overall
decreasing trend in contaminant concentration.

If, based on monitoring data, this trend does not continue or the concentrations start to
increase, the AF will implement active remediation.  The trigger conditions for active
remediation are described in more detail in Section 3.8.3.3.

3.8.23  Long-Term Effectiveness and Permanence.  All of the groundwater extraction
alternatives will capture and clean up the East Base Plumes to MCLs or more stringent
standards, leaving no significant potential health or environmental risks. Therefore, all were
assigned a score of 5 for all process options.

The Impacted Area Well Destruction and Monitoring alternative would not reduce the extent
of existing groundwater contamination. However, abandonment of the only existing receptor
wells impacted or potentially impacted by the East Base Plumes will eliminate potential

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health impacts. Operation of the OU 1 and OU 2 extraction systems will prevent off-site
migration of the East Base Plumes. Therefore, this alternative was assigned a score of 3.

The No Action alternative would not reduce the extent of groundwater contamination, aside
from any natural attenuation, and no measures would be taken to prevent human exposure or
further degradation of the environment. Therefore, the No Action alternative was assigned a
score of 1.

3.8.2.4 Reduction of Mobility, Toxicity, or Volume. The O.S ug/L TCE Capture
alternative would capture and clean up the plumes to near background conditions, achieving a
significant reduction in plume toxicity, mobility, and vokime.  Two of the associated
treatment options would directly (UV/oxidation) or indirectly (thermal reactivation of spent
GAC) permanently destroy the contaminants. Therefore, for this alternative, these process
options are assigned scores of 5. The air stripper would release the contaminants to the
atmosphere. Therefore, for this alternative, the air stripper option was assigned a score of 4.

The volumes of the 5 ug/L and 3 ug/L TCE plumes are 39 percent and 47 percent,
respectively, of the volume of the plumes defined by the 0.5 pg/L TCE Capture alternative.
The associated masses of TCE for these plumes are 56 percent and 67 percent, respectively,
of the mass of TCE for the 0.5 ug/L TCE plumes. Therefore, the 5 pg/L and 3 ug/L TCE
Capture alternatives were assigned scores of 4 for the UV/oxidation and L-P GAC process
options.  The air stripper process option was assigned a score of 3 for these two alternatives.

The Impacted Area Well Destruction and Monitoring alternative would not actively reduce
the volume or  mobility of the East Base Plumes, but may prevent significant cross
contamination between the HSZs. Therefore, this alternative was assigned a score of 3.

The No Action alternative would not, aside from natural attenuation, produce any reduction
in the volume, mobility, or toxicity of the East Base Plumes.  Therefore, the No Action
alternative  was assigned a score of 1.

3.8.2.5 Short-Term Effectiveness. The No Action alternative does not pose any risk to
workers or the public since no actions are taken and the alternative requires no time to
complete. Therefore, the No Action alternative was assigned a score of 5.  The only
anticipated action for the Impacted Area Well Destruction and Monitoring alternative is
destruction of on-site wells. These actions will pose no significant risk to workers or the
public and  can be completed quickly. Therefore, this alternative was also assigned a score of
5.

More significant worker exposure could occur during implementation of the three extraction
alternatives, especially during construction of extraction and injection wells and trenching for
installation of conveyance piping. The air stripper process option may pose a slight risk due
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to the emission of VOCs to the atmosphere. The primary differences among the three
extraction alternatives are the increase in potential for worker exposure as the capture
objective is made more stringent due to the increased number of wells and trenching required
and the increased time required to complete the RA. Therefore, the 5 ug/L TCE Capture
alternative was assigned a score of 4; the 3 ug/L TCE Capture alternative was assigned a
score of 3; and the 0.5 ug/L TCE Capture alternative was assigned a score of 2 for all process
options.

3.8.2.6 ImplementabUity. There are  no technical or administrative difficulties for the No
Action alternative, therefore, it was assigned a score of 5. The only action proposed for the
Impacted Area Well Destruction and Monitoring alternative is the destruction of on-site wells
and associated monitoring. No technical or administrative difficulties are anticipated for this
alternative, therefore, it was assigned a score of 5.

The three extraction alternatives all utilize proven technologies for groundwater extraction,
treatment, and disposal. However, the uncertainty of ever achieving the cleanup objectives
increases as the concentration set for the cleanup objectives is decreased.  Cleanup to 0.5
ug/L TCE in groundwater may be technically impractical and cost prohibitive.  Groundwater
extraction and injection is limited to the shallow HSZ for the East Base Plume region.
Therefore, few technical problems are anticipated for the injection disposal option
alternatives. The scoring of the three extraction alternatives considers these factors. The 5
Mg/L TCE Capture alternative was thus assigned a score of 4 for the UV/oxidation and L-P
GAC treatment options, and 3 for the air stripping treatment option. The 3 ug/L TCE
Capture alternative was assigned a score of 4 for the UV/oxidation and L-P GAC treatment
options and 3 for the air stripping treatment option.  The 0.5 pg/L TCE Capture alternative
was assigned a score of 3 for the UV/oxidation and L-P GAC treatment options and 2 for the
air stripping treatment option.

3.8.2.7 Cost A cost comparison of the alternatives fofthe East Base Plumes is presented in
Table 3-16 and below.  No Action has the lowest cost of all alternatives, as costs for
continued groundwater monitoring are all that are involved. The 0.5 ug/L TCE Capture
alternative with UV/oxidation treatment has the highest cost Costs estimated for each of the
groundwater extraction and treatment  alternatives consistently indicate that the air stripping
treatment alternative is the least costly of the three treatment technologies.

Scores were assigned to each of the alternatives based on present worth costs according to the
method described in the introduction of this section.
Alternative
No Action

Impacted Area Well Destruction and Monitor
Cost ($M)
0.5

0.5
Score
5

5
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Alternative

The 5 ug/L TCE Capture
(a) Air Stripping with Injection
(b) UV/Oxidation with Injection
(c) L-P GAC with Injection

The 0.5 ug/L TCE Capture
(a) Air Stripping with Injection
(b) UV/Oxidation with Injection
(c) L-P GAC with Injection

The 3 ug/L TCE Capture
(a) Air Stripping with Injection
(b) UV/Oxidation with Injection
(c) L-P GAC with Injection
Cost($M)


4.0
6.0
5.8


5.8
7.9
7.7


4.0
6.0
5.8
Score


3
2
2


2
1
1


3
2
2
3.8.3 Summary of Analysis and Remedy Selection.  This section provides a summary of
the scoring of the alternatives for the Main and East Base Plume regions and more complete
descriptions of the selected remedies.

3.8.3.1 Main Base Plume Regions. The total scores for the remedial alternatives analyzed
and ranked for the Main Base Plume regions ranged from 21 to 28 (Table 3-13).  The highest
ranking sub-alternative, with a score of 28, was 3B, the 5 u,g/L TCE Capture alternative using
L-P GAC and canal discharge of treated water. A score of 27 was received by several sub-
alternatives including 3A, 5 ug/L TCE Capture with air stripping and canal discharge; 5B, 3
ug/L TCE Capture with L-P GAC and canal discharge; and 6B, Plume Control with L-P
GAC and canal discharge.

Based on these results, the Proposed Plan identified Alternative 3, Plume Capture with a 5
Mg/L TCE-cleanup objective, as the recommended remedy- Community acceptance-and state
concurrence for the recommended remedy was established through the public comments
received during the comment period for the Proposed Plan, and through the incorporation of
substantial additional state input based on comments on the Preliminary Draft and Draft Final
ROD.  The Responsiveness Summary (found at Tab 3) provides a summary of both public as
well as state comments and comment responses.

3.8.3.2 East Base Plume Region.  The total  scores for the remedial alternatives analyzed
and ranked for the East Base Plume region ranged from 23 to 28 (Table 3-14). The highest
ranking alternative was Alternative 2; Well Destruction and Monitoring.  The Impacted Area
Well Destruction and Monitoring alternative for the East Base Plume region consists of.
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destroying production wells that are screened across the shallow and USS HSZs and have the
potential to act as vertical conduits to transfer contaminants to the lower HSZs followed by
continued monitoring and further action, if necessary.

Based on these results, the Proposed Plan identified Alternative 2, Well Destruction and
Monitoring, as the recommended remedy. Community acceptance and state concurrence for
the recommended remedy was established through the public comments received during the
comment period for the Proposed Plan, and through the incorporation of substantial
additional state input based on comments on the Preliminary Draft and Draft Final ROD.
The Responsiveness Summary (found at Tab 3) provides a summary of both public as well as
state comments and comment responses.

3.8.3.3 Selected Remedy

Main Base Plume. The selected remedy for the Main Base Plume is Alternative 3, Plume
Capture with a 5 ng/L cleanup objective, implemented with a phased approach; this remedy
will build on and incorporate the ongoing and planned remedial activities authorized in the
OU 1 Interim ROD and the OU 2 Final ROD. Implementation of the selected remedy would
be the most effective remedial strategy to capture and clean up the contaminated groundwater
to MCLs.  The phased approach was chosen in order to allow for the collection and use of
information from technical effectiveness studies of OU 1 and OU 2 systems and to provide
direction for installation of additional treatment systems.

It is intended that the selected remedy under this ROD will incorporate and therefore
supersede the previous groundwater cleanup RODs (i.e., OU  1 and OU 2). Consequently, the
selected remedy includes flexibility in the treatment technology and treated water disposal
approaches to be applied for the Main Base Plume. The remedy includes a provision for the
use of both GAC and Air Stripping treatment technologies and the application of reinjection,
surface discharge, and other reuse for the disposal of the treated groundwater.  Refer to the
RI/FS and the RBDR reports for additional detail on each element of this selected remedy.

The selected remedy for the Main Base Plume consists of the following three sequential
phases of pump and treat groundwater remediation:

Phase 1: Phase 1  takes advantage of existing OU 1 treatment capacity as well as additional
system expansion, to remove TCE and control migration of TCE "hot  spots" in the shallow
HSZ. This is being accomplished by expanding the OU 1 extraction system through
installation of new extraction wells in the shallow HSZ.  GAC and/or air stripping
groundwater treatment systems will be utilized to achieve effluent release levels discussed in
Section 3.8.3.4 and presented in Section 4 of this ROD. Design of the OU 1 expansion is
being included in the RBDR. In addition, the OU 2 groundwater extraction network will be
completed and operations initiated.
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Phase 2: Phase 2 will enhance the OU 1 extraction network to a multiple HSZ groundwater
remediation system with the addition of extraction wells and the utilization of GAC or air
stripper treatment systems to achieve effluent release levels stipulated in this ROD (see
Section 3.8.3.4 and Section 4). A water reuse study will be used to determine the most
appropriate combination of reinjection, canal discharge, and water reuse to be utilized for the
disposal of treated groundwater.  Pump tests will be conducted to obtain necessary hydrologic
information on HSZ properties.

Phase 3: Data collected from the first two phases will be evaluated and a Phase 3 Technical
Evaluation and Design Study will be prepared to determine what additional RAs will be
needed to achieve the overall cleanup objectives. By the onset of Phase 3, both Phase 1 and 2
pump and treat systems will have been installed, data gap wells and the LTGSP network will
be in place, pump tests will have been evaluated, and the flow and transport models will have
been updated. That information will facilitate better analysis of the hydraulic control of
HSZs and plume remediation time periods and will provide information needed in the design
of additional treatment systems.

The selected remedy is expected to cost-effectively remove TCE and other contaminants in
the Castle AFB groundwater to the MCL cleanup objective and prevent further plume
migration. The preliminary range of the estimated present worth costs of the selected remedy
is from $15.7 to $33.4 million over a period of 15 years.  The remedy is protective of human
health and the environment and is in compliance with all ARARs.

The three phases of groundwater remediation will be fully developed during RD/RA stages.
The selected remedy will address the principal threat of groundwater contamination.
Contaminants in the Castle AFB groundwater will be captured within the boundary of the
5 pg/L TCE iso-concentration contour and cleaned up to  the MCLs (i.e., 5 ug/L TCE).
Section 4 provides the release levels for treated groundwater.
                                               a
Groundwater treatment technologies incorporated in this  remedy include air stripping and
L-P GAC treatment. The optimal combination of these selected treatment technologies will
be based on engineering and cost analysis conducted in the RBDR.- Selection factors may
include the availability of capacity from the OU 1 (air stripping) and OU 2 (L-P GAC)
systems, the proximity of well locations to existing systems, and the economics of local
versus central treatment. The optimal combination of reinjection, canal discharge and reuse
for groundwater disposal will also be evaluated in the RBDR. Similar factors will impact
discharge alternatives, namely available capacity of existing systems, proximity to existing
systems, alternative discharge locations such as the sewer or canal, economics, and
agreements with water resource authorities.

Schedule for Implementation of Three Phase Approach. The approximate schedule for
the three phases of the selected remedy will be as follows:
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       Phase                     Year
         1                       1996
         2                       1997-1998 (approximately 18 months)
         3                       1998 to completion of RA

East Base Plume. Implementation of the selected remedy (Alternative 2: Impacted Area
Well Destruction and Monitoring) for the East Base Plume utilizes the sealing and
abandonment of wells to prevent further cross contamination of HSZs in the East Base Plume
area, and monitoring to develop more complete definition of the plume.  An annual
evaluation will be done as part of the LTGSP to determine if implementation of a pump and
treat technology^ necessary. The AF will continue monitoring the East Base Plume region
to enhance characterization of the plume(s) and detect any changes. Within one year of the
approval date of this ROD, the AF will provide a reassessment of the need for active
remediation to the agencies.  In the event this reassessment results in a decision not to
implement active remediation, the plume area will be reassessed annually until either active
remediation is initiated or the level of contamination is determined to have fallen below
cleanup levels for a period of at  least one year.  In addition, if any of these assessments show
through .model ing. and/or jnpnitpring, tjiajjhejcpntaminant concentrations wjlHncrease-Qi. not
continue to^al[ below the cleanup le^vels within a reasonable time, or at least forty years from
the date ofjhis^ ROD, or that plume migration of the contaminants may occur at levels above
the cleanup levels, active remediation will be implemented. The estimated present worth cost
of the Impacted Area Well Destruction and Monitor alternative for the East Base Plume
(excluding any costs associated with the Main Base Plume Selected Remedy) is $0.5 million
over 30 years. Alternative 2 is the most cost-effective RA.

Castle Vista Plume. Although detailed analysis was not conducted for the Castle Vista
Plume in the CB-Part 1  RI/FS, it was recognized that additional data collection was needed.
Data collected since the RI/FS indicates the need for active groundwater remediation in the
Castle Vista area; therefore, the pump and treat approach will be implemented as the
presumptive remedy for the needed further cleanup action. These cleanup requirements,
identified in the overall objective of the Castle AFB CB-Part 1 RAs, entail capturing the
contaminant plume and cleaning up the contaminated groundwater to the MCL level of the
most restrictive contaminant present.  For the Castle Vista Plume, further analysis will be
conducted to determine the appropriate cleanup level. Consistent with the approach of
Section fflG of SWRCB Resolution 92-49. This evaluation will be carried out as part of the
RD/RA activity.  For the purpose of operational and reporting convenience and efficiency,
this additional action will be integrated into the phased approach of the CB-Part 1 RD/RA
described under the remedy for the Main Base Plume.

Other Plumes. The AF, with the concurrence of EPA and Cal/EPA, has determined that
active remediation of the North Base, Landfill 1, and Landfill 4 plumes is not warranted at
this time because action is being taken to remediate the sources, and because removing the
low concentration contaminants from the groundwater would provide little benefit while

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incurring high costs. However, because several of the contaminants are above primary
drinking water standards, institutional controls will be implemented to prevent the
installation of groundwater supply wells on Castle AFB that would jeopardize public health
or the environment from these plumes. Additionally, long-term monitoring will be
performed under the LTGSP to monitor contaminant concentrations in these plume areas.
Monitoring will be conducted pursuant to Title 23, California Code of Regulations (CCR),
Section 2550.10 (Corrective Action Monitoring) for at least one year from the date that MCL
and beneficial use concentrations for each respective COC are attained.  After that time,
landfill monitoring will be conducted pursuant to Title 23, CCR, Section 2550.8 (Detection
Monitoring), in order to detect potential future releases from Landfill 5, Landfill 4, and
Landfill 1 sites. Contaminant concentration levels in the groundwater will be reevaluated
annually. If the contaminant concentrations drop below the MCL and beneficial use
concentrations for one year, any institutional controls may be removed.  If, at any time,
monitoring or modeling indicates that the contaminants will not meet the MCL and beneficial
use concentrations within a reasonable time, or at least forty years from  the date of the ROD,
or that significant migration of the contaminants may occur at levels above MCL and
beneficial use concentrations which impact public health or the environment, active
remediation will be considered.

3.8.3.4 Discharges from the Groundwater Treatment Systems.  The remedies selected for
groundwater cleanup of the Main Base and Castle Vista Plumes involve multiple treatment
and groundwater disposal options, as described previously. Four other plumes, the East Base,
the North Base, Landfill 1 and Landfill 4 plumes, are subject to continued monitoring and
trigger conditions to prompt, when necessary, future implementation of pump, treat and
discharge systems, after this ROD has been finalized.

Discharges of treated water have the potential to affect beneficial uses of surface and/or
groundwater. The ARARs and requirements triggered for any discharge are dependent on
many factors, including the constituent composition of the treated water, the location of the
discharge, and the quality and beneficial uses of the receiving water.

This ROD encompasses the following four discharges: 1) reinjection of treated groundwater
generally upgradient of the OU 1 treatment system (existing discharge); 2) reinjection
downgradient of the OU 2 treatment system (existing discharge); 3) discharge to Casad
Lateral as backup to the existing OU 2 system (existing permit); and 4) discharges to the
storm drain and Canal Creek (new discharge).  Alternative discharge methods and/or
locations for the Main Base Plumes discharges will be evaluated in the Water Reuse Study
and supporting documents in Phase 2.  The AF may propose discharges other than those
described above in future design reports.

The two existing reinjection systems for the OU 1 and OU 2 groundwater treatment systems
discharge treated water into the same aquifer or zone from which the water was extracted.
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Both reinjection systems are designed to maintain hydraulic control of the plumes.  The OU 1
reinjection system is at the upgradient edge of the Main Base Plume and includes injection
wells JI-1 through 9.  The OU 2 reinjection system is at the downgradient and northern edges
of the OU 2 Plume and includes injection wells HPIW-1 through 11. The discharge limits for
reinjection and surface discharge of treated groundwater, regardless of the plume area, are
provided in Section 4.

The third discharge of treated groundwater is to the Casad Lateral and is a backup to the OU
2 reinjection system in case this system has operational problems and cannot handle the flow
(temporary discharge) or if the reinjection system cannot handle the design flows and
additional discharge capacity is needed (long-term discharge). Any discharge to the Casad
Lateral will comply with the ARARs identified in Section 4 and regional water board
requirements.

The fourth discharge of treated groundwater is a new discharge to the storm drain system that
discharges to Canal Creek, a surface water. Stormwater from the base is also collected in this
storm drain system. These two discharges will commingle prior to discharge to Canal Creek.
The stormwater portion of the discharge is regulated according to a National Pollutant
Discharge Elimination System (NPDES) Permit issued by the Regional Water Quality
Control Board.  The discharge point to Canal Creek is in Section 4, T7S, R13E, MDB&M, at
the  point latitude N37° 2 11" and longitude W120° 33* 36".

The present design flow for discharge of treated groundwater to the storm drain is  144,000
gallons per day (100 gpm). The flow is expected to increase in phases in the future. The
maximum discharge flow from the groundwater treatment system is 1,440,000 gallons per
day (1,000 gpm). In the event of a need to increase surface discharge rates above the present
design flow (100 gpm), the AF will submit a technical report, prior to implementing any such
increase, as a primary document under the Castle AFB Federal Facility Agreement. The
report will demonstrate that the treatment system, the conveyance system (the storm drain)
and Canal Creek has sufficient capacity to accommodate the new design flow. The
stormwater drain flow will include the effects of the treatment system flow rate and the flow
from a 24-hour, 100-year flood. All discharge requirements in this ROD, including effluent
limits and receiving water limits, will apply to the new flow rate.

Alternative discharge options will be evaluated during remedial design.  The design will
incorporate the discharges described in this ROD, and evaluate other discharge options and
locations according to the Regional Board's Policy for Reuse that are (a) consistent with
attainment of cleanup standards, and (b) cost-effective. The design will include contingency
planning to avoid or minimize disruption of treatment operations should the primary
discharge options be compromised (i.e., if reinjection capacity declines).  Any means  of
discharge must meet substantive requirements of ARARs, if on site, or be permitted as
required  if off site. A ROD Amendment or ESD will be prepared for any discharge or
disposal  alternatives other than the four discharges documented in this ROD. Prior to

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adoption of a ROD Amendment or BSD, the AF will solicit state and federal ARARs and
provide for public notice and comment and response to comments.

Examples of discharge options and locations are:

•  injection to a deeper aquifer;
•  recharge through the vadose zone using injection wells, infiltration ponds, or infiltration
   galleries;
•  surface water discharge;
•  provisions of water to industrial/agricultural users;
•  provisions of water to municipal supply; and
•  irrigation (landscaping, wetlands).

The selected remedy 1) prohibits the bypass or overflow of untreated or partially treated
waste; 2) limits discharge to injection of treated water to those injection systems described
above; 3) requires that the pH of any treated water shall be between 6.5 and 8.5 or equivalent
to receiving waters.

Prior to any new discharge, initial background concentrations of all potential pollutants in the
receiving water shall be determined (in each water-bearing zone for reinjection, or in the
surface discharge). If the data necessitate the establishment of reinjection standards for
additional constituents in order to meet ARARs, an amendment to the ROD or other
appropriate decision procedure  will be considered by the AF, EPA, DTSC and Regional
Board.  These constituents will  be monitored in the effluent during RA to determine that the
discharge meets all requirements.

3.8.3.5  Monitoring for Groundwater Treatment Systems. All of the selected remedies
include groundwater and groundwater effluent monitoring. The objectives for the
Monitoring Program are described below. In addition, the Program will meet ARARs listed
in Section 4 of this ROD and will be used to evaluate when the selected remedy will meet the
cleanup objectives. Therefore,  the monitoring well network and sampling frequency, and
treatment system sampling locations and frequency need to be sufficient to meet the
monitoring objectives. The following are the Program objectives:

•  Demonstrate that the extraction system capture zone is completely containing the plume
   at the aquifer cleanup standards for each COC.

•  .Demonstrate the overall effectiveness of the groundwater treatment system (i.e., are the
   contaminant concentrations being reduced? Is the remedy on schedule to meet aquifer
   cleanup standards?).
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•  Demonstrate for plumes that are not being actively remediated, that plume boundaries are
   not expanding, contaminant concentrations are decreasing, and the aquifer cleanup
   standards will be met within the prescribed period.

•  Demonstrate that the aquifer cleanup level has been met for a sufficient period of time to
   allow termination of pumping at an extraction well.

•  Demonstrate that the treated groundwater is meeting effluent limits, receiving water
   limitations and all other requirements contained in this ROD.

The demonstration that the monitoring has met these objectives will be presented in the
LTGSP reporting.

3.9    STATUTORY DETERMINATIONS

3.9.1  Main Base and Castle Vista Plumes. The selected remedy is protective of human
health and the environment as required by Section 121 of CERCLA.  The selected RA, when
complete, will comply with applicable or relevant and appropriate environmental standards
established under federal and state environmental laws. The selected remedy is cost-
effective, uses permanent treatment technologies to the maximum extent practicable, and
includes treatment as a principal element. The following sections discuss how the selected
remedy meets the statutory requirements. (Table 3-13 provides a comparative analysis of
alternatives considered for the Main Base Plume.)

3.9.1.1 Protection of Public Health and the Environment The selected remedy uses
proven pump and treat remediation technology to capture the contaminated groundwater
plume(s) within the existing boundary and clean up the groundwater to MCLs. This remedy
will significantly reduce the threat of exposure to residents and occupational workers. The
implementation of this remedy will not create unacceptable short-term risks nor any negative
cross-media impacts.

3.9.1.2 Attainment of ARARs. All ARARs will be met by the selected remedy. The
remedy will achieve compliance with chemical-specific ARARs by treating groundwater to
concentrations equal to or below the chemical-specific effluent standards.  Action-specific
ARARs will be met for the disposal of groundwater. RCRA requirements will be met for the
treatment facility, and storage and handling of spent carbon.

3.9.1.3 Cost-Effectiveness. The AF, the EPA,  and the state believe that the selected remedy
provides overall effectiveness in relation to its cost. Based on the evaluation of alternative
remedial approaches, the selected alternative for the Main Base Plume has a capital cost of
approximately $20.1 million and an approximate present value Operations and Maintenance
(O&M) cost of $13.3 million. The total net present value is $33.4 million, based on a 15-
year estimate for the time required to clean up the Main Base Plume. These cost estimates

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are based on the concepts evaluated in the CB-Part 1 FS analyses for the Main Base Plume.
The actual remedial costs of the CB-Part 1 selected remedy which integrates OU 1 and OU 2
systems may differ significantly from these values, but will represent a cost-effective
approach to the cleanup of the Main Base Plume.

3.9.1.4 Use of Permanent Solutions and Alternative Treatment Technologies or
Resource Recovery Technologies to the Maximum Extent Practicable. The selected
remedy utilizes permanent solutions and treatment technologies to the maximum extent
practicable. Of those alternatives that are protective of human health and the environment
(and comply with ARARs), the AF, with concurrence from the EPA and the state, have
determined that the selected remedy provides the best balance of long-term effectiveness and
permanence; reduction of toxicity, mobility and volume through treatment; short-term
effectiveness; implementability and cost-effectiveness.

The groundwater extraction and treatment to be utilized for the selected remedy offers the
best long-term effectiveness and permanence for groundwater remediation at Castle AFB. It
also offers the second best method for the reduction of groundwater contaminant toxicity,
mobility, and volume of those alternatives that included treatment. Short-term effectiveness
was highest of any plume capture alternative. With the chosen phased approach, utilizing the
pump and treat technology, the selected remedy has moderate implementability, although
those alternatives with less aggressive cleanup approaches have higher feasibility. The
selected remedy has the lowest costs of any plume capture alternatives considered.

Of the five primary balancing criteria, the most decisive factors in the selection of the remedy
were the long-term effectiveness and permanence, reduction of toxicity, mobility, and volume
through treatment and cost.

The state and the EPA acceptance of this remedy were factored into the decision by
establishing an agreed-upon cleanup objective, and identifying which alternative(s) met the
objective. In addition, state and EPA inputs significantly affected the decisions documented
in this ROD.  Agency comments and responses to  these comments can be found in the
Responsiveness Summary at Tab 3.                                - «•

3.9.1.5  Preference for Treatment as a Principal Element The selected remedy provides
the best balance of trade-offs among the alternatives with respect to the evaluation criteria.
The principal threat of current well contamination, plume migration and further
contamination of production wells posed by the contaminated groundwater at Castle AFB
will be remedied with the pump and treat system utilized by the selected remedy.

3.9.2 East Base Plume. The selected remedy is protective of human health and the
environment as required by Section 121 of CERCLA. The selected RA, when complete, will
comply with applicable or relevant and appropriate environmental standards established
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under federal and state environmental laws.  The selected remedy is cost-effective, but does
not use permanent treatment technologies or treatment as a principal element unless a pump
and treat presumptive remedy is implemented. The following sections discuss how the
selected remedy meets the statutory requirements. (Table 3-14 provides a comparative
analysis of alternatives considered for the East Base Plume.)

3.9.2.1 Protection of Public Health and the Environment Alternative 2 provides for
protection of the public health and the environment by preventing the flow of contaminants
into the groundwater and monitoring to determine the need for further active treatment. In
the event further actions are appropriate, pump and treat remediation technology will be
implemented as the presumptive remedy. This remedy will significantly reduce the threat of
exposure to residents and occupational workers. The implementation of this remedy will not
create any short-term risks nor any negative cross-media impacts.

3.9.2.2 Attainment of ARARs.  All ARARs will be met by the selected remedy. The
remedy will achieve compliance with chemical-specific ARARs by preventing their
migration to the groundwater, and to the extent needed, by treating groundwater to
concentrations at or below the chemical-specific cleanup standards. Action-specific ARARs
will be met for the injection of groundwater if the presumptive remedy pump and treat
technology is implemented. RCRA requirements  will be met for the treatment facility, and
storage and handling of spent carbon, if required.

3.9.2.3 Cost-Effectiveness. The AF, the EPA, and the state concur that the selected remedy
provides overall  effectiveness in relation to its cost.  Alternative 2 has a capital cost of
approximately $0.01 million and an approximate present value O&M cost of $0.53 million.
The total net present value is $0.54 million based on a 30-year estimate for the time required
to clean up the East Base Plume.

3.9.2.4 Use of Permanent Solutions and Alternative Treatment Technologies or
Resource Recovery Technologies to the Maximum Extent Practicable. The selected
remedy does not utilize permanent solutions and treatment technologies. However, of those
alternatives that are protective of human health and the environment (and comply with
ARARs), the AF, the EPA, and the state concur that the selected remedy provides the best
balance of long-term effectiveness and permanence; reduction of toxicity, mobility and
volume through treatment; short-term effectiveness; implementability; and cost-effectiveness.

Of the five primary balancing criteria, the most decisive factors in selection of the remedy
were the short-term effectiveness, implementability, and cost.

The state and the EPA acceptance of this remedy were factored into the decision by
establishing an agreed-upon cleanup objective, and identifying which alternative(s) met the
objective. In addition, state and EPA inputs significantly affected the decisions documented
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in this ROD. Agency comments and responses to these comments can be found in the
Responsiveness Summary at Tab 3.

3.9.2.5 Preference for Treatment as a Principal Element The selected remedy provides
the best balance of trade-offs among the alternatives with respect to the evaluation criteria,
but does not meet the preference for treatment as a principal element.  In the event further
active remediation is indicated, pump and treat technology will be implemented as the
presumptive remedy for further cleanup action, and this would meet the preference for
treatment as a principal element.
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4.0   LIST OF APPLICABLE OR RELEVANT AND APPROPRIATE
      REQUIREMENTS AND TO-BE-CONSIDEREDS

In this section, the ARARs for CB-Part 1 are identified and discussed. The ARARs
presented here are based on analyses carried out during the evaluation of remedial
alternatives at Castle AFB and on input and discussions between the AF, the EPA and the
state.

Pursuant to Section 121(d)(l) of CERCLA, RAs must attain a degree of cleanup which
assures protection of human health and the environment. Additionally, RAs that leave
hazardous substances, pollutants, or contaminants on site must meet standards, requirements,
limitations, or criteria that are ARARs. Federal ARARs include requirements under any
federal environmental laws, while state ARARs include promulgated requirements under
state environmental or facility-siting laws that are more stringent than federal ARARs, and
that have been identified to the AF by the State of California in a timely manner.

Applicable requirements are those cleanup standards, control standards, and other substantive
environmental protection requirements, criteria, or limitations promulgated under federal or
state law that specifically address a hazardous substance, pollutant, contaminant, RA,
location, or other circumstance at a CERCLA site. In general, on site actions need comply
only with the substantive aspects of ARARs, not with corresponding administrative
requirements (such as, but not limited to, permits, record keeping, and reporting).

Relevant and appropriate requirements include those that, while not "applicable" to a
hazardous substance, pollutant, contaminant, RA, location, or other circumstance at a
CERCLA site, nevertheless address problems or situations sufficiently similar to those
encountered at the CERCLA site to indicate their use is well suited to the particular site. A
requirement must be either applicable or both relevant and appropriate to be an ARAR.  If no
ARAR addresses a particular situation, or  if an ARAR is insufficient to protect human health
or the environment, then nonpromulgated standards, criteria, guidance, and TBC advisories
may be used to develop a protective remedy.

ARARs are identified on a site-specific basis from information about site-specific chemicals,
specific  actions that are being considered as remedies, and specific features of the  site
location. There are three categories of ARARs:

•  Chemical-specific ARARs are numerical values or methodologies which, when applied to
   site-specific conditions, result in the establishment of numerical values. They  are used to
   determine acceptable concentrations of specific hazardous substances, pollutants, and
   contaminants in the environment;
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•  Location-specific ARARs are restrictions placed on the concentration of hazardous
   substances or the conduct of activities solely because the site occurs in, or may affect, a
   special location such as a wetland or floodplain; and

•  Action-specific ARARs are technology- or activity-based requirements or limitations on
   actions taken with respect to hazardous waste.

The ARARs and TBCs were developed using the following guidelines and documents:
CERCLA Compliance with Other Laws Manual, Part I: Interim Final [EPA 1988];
"CERCLA Compliance with Other Laws Manual, Part II: Clean Water Act and Other
Environmental Statutes and state Requirements" [EPA 1989b]; and "California SWRCB
ARARs Under CERCLA" [State Water Resources Control Board 1992].

The following sections present the federal and state regulations and guidance under each
appropriate ARAR category (i.e., chemical-, location-, and action-specific). Chemical-
specific ARARs and TBCs are addressed in Section 4.1, location-specific ARARs and TBCs
in Section 4.2,  and action-specific ARARs and TBCs in Section 4.3.

4.1     CHEMICAL-SPECIFIC ARARs AND TBCs

COCs for groundwater plumes are discussed in the following subsections. The chemical-
specific ARARs and TBCs for these COCs are presented based on whether they are ARARs
or TBCs, the type  of contamination, and applicable media. Table 4-1 lists the chemical-
specific ARARs for drinking water and groundwater.

4.1.1   Federal Chemical-Specific ARARs and TBCs. Section 121 of CERCLA indicates
that RAs shall attain federal water quality guidance (WQG) or AWQC where they are
relevant and appropriate. National Primary Drinking Water regulation, 40 CFR Part 141,
established MCLs and MCL goals for organic and inorganic constituents as ARARs.

4.1.2   State Chemical-Specific ARARs and TBCs. The Porter-Cologne Water Quality
Control Act is  one of the statutory bases for remediation of contaminants that threaten water
quality in California.  It establishes the authority of the SWRCB and the Central Valley
Regional Water Quality Control Board (CVRWQCB) to protect the quality of surface water
and groundwater in California.

SWRCB Resolution 68-16 has been identified as an applicable requirement for the protection
of surface water and groundwater of the state. The AF and the state do not agree on the full
applicability of all the substantive requirements contained within the resolution and the
impact on the remedial activities needed to clean up Castle AFB. The AF disagrees with the
state's contention  that the narrative language establishes chemical-specific ARARs for both
soil and groundwater, and that discharges subject to the resolution include post-1968
migration of in situ contamination from the vadose zone to groundwater. The AF believes

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that only active discharges directly to surface water or groundwater of the state are subject to
the provisions of SWRCB Resolution 68-16. However, the remedies selected are intended to
control further migration and, therefore, comply with Resolution 68-16 as interpreted by the
RWQCB.

Portions of the CVRWQCB Basin Plan [CVRWQCB 1995] for Sacramento-San Joaquin
Basin which are listed in Table 4-2 contain narrative water quality objectives which were
used to arrive at chemical-specific requirements that pertain to the Castle AFB area. The
Basin Plan [CVRWQCB 1995] designates the beneficial uses of the groundwater in the
Castle AFB area as domestic, municipal, irrigation, stock water, process, and service supply
waters.  Based on these uses, the methodology for arriving at the numeric standards necessary
to attain the narrative taste and odor objective (an ARAR) is a TBC requirement. In addition
to the TBCs, the Basin Plan establishes the following qualitative chemical-specific ARARs
based on the designated use(s) of the groundwater: the domestic or municipal water supply
shall not contain concentrations of chemicals in excess of state required MCLs; and the
agricultural water supply shall not contain concentrations of constituents that adversely affect
its beneficial use.

4.2    LOCATION-SPECIFIC ARARs AND TBCs

Location-specific ARARs and TBCs are requirements that place restrictions on the
concentration of a COC or the conduct of activities because of the presence of unique site
features such as surface waters and wetlands. The location of the groundwater site for RA
was analyzed for unique site features to identify location-specific ARARs. The unique site
features considered were:

•  surface water;
•  floodplain and wetlands;
•  habitats of rare, threatened, endangered, and special status species;
•  earthquake faults;
*  historically or culturally significant properties;
•  wilderness areas;
•  wild and scenic rivers, and coastal zones.

At Castle AFB, 100-year floodplains occur on Canal Creek; the floodplains overlap the
southeastern and southernmost portions of the base.  Vernal pools, which may contain an
endangered species, have been identified at Castle AFB.  Currently there has been
documentation that endangered species exist in these pools and investigations are ongoing.
No other unique site features were identified.

4.2.1   Federal Location-Specific ARARs. The Endangered Species Act and implementing
regulations at 50 CFR 17,222,226,227, and 402 apply to some of the RAs at Castle AFB if
they impact endangered wildlife. These impacts may be identified by a final biological

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assessment finding that the vernal pools on Castle AFB contain an endangered species. No
vernal pools have been identified in the vicinity of any of the groundwater sites for which RA
is selected in this ROD. The direct cleanup activities are not expected to impact any
endangered species; however, associated cleanup activities (i.e., construction of pipelines for
groundwater injection) may impact habitat or critical resources. All activities must ensure
that regulatory requirements are followed and impacts avoided or mitigated.

4.2.2  State Location-Specific ARARs. The Fish and Game Code Section 1600 requires
that any work within the 100-year floodplain (consisting of, but not limited to, diversion or
obstruction of the natural flow or changes in the channel, bed, or bank of any river, stream or
lake) will involve mitigation measures to avoid or minimize impacts on natural resources.
Certain provisions of the Fish and Game Code Section 1600 would be relevant and
appropriate for this groundwater RA site if the site or any of the associated cleanup activities
(i.e., construction of pipelines for groundwater injection) is actually  located in the 100-year
floodplain.

4.3    ACTION-SPECIFIC ARARs AND TBCs

Action-specific ARARs are technology or activity-based requirements or limitations on
actions taken with respect to the hazardous waste. The following sections describe the state
and federal action-specific ARARs and TBCs. All ARARs are listed in Table 4-2 with each
substantive requirement identified as applicable, relevant and appropriate, or TBC. Several
of the requirements are marked with a footnote giving clarification to either their ARAR
status or the legal interpretation of why they are considered ARARs for a particular site or
RA. The TBCs are discussed in Section 4.3.2.3. Sections 4.3.1 and 4.3.2 include
descriptions of the sources of the action-specific ARAR regulations and the authorization the
state regulatory agencies have to enforce these requirements. In addition, the AF position on
substantive requirements of ARARs and how they apply to the selected RAs are described.

4.3.1  Federal ARARs.  The following federal action-specific ARARs have been identified.
The federal action-specific ARARs are listed in Table 4-2", and a brief description of the
sources of action-specific ARARs are provided in this  section.

The Federal Safe Drinking Water Act regulates the injection of waste into injection wells.
These wells are identified by unique characteristics such as depth, location of drinking water
source, and material injected. The Underground Injection Control Program (40 CFR 144) is
the regulation listing the requirements for the operation and use of injection wells.

4.3.2  State ARARs and TBCs.  The state action-specific ARARs and TBCs are listed in
Table 4-2, and are discussed in the following sections. Included are brief descriptions of the
source of the ARARs and identification of the regulations derived under the source. Also
presented is the AF position on substantive requirements of these ARARs and how they
apply to the selected remedial actions.

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43.2.1  State Air ARARs.  The California Clean Air Act, under the Federal Clean Air Act
and 1990 Amendments, authorizes the State of California to develop a State Implementation
Plan (SIP) to enforce clean air regulations and laws. The SIP, developed through state
legislation, divided the state into local air control districts and allowed each district to enforce
the requirements of the Federal and State Clean Air Acts. Castle AFB is located in the San
Joaquin Valley Unified Air Pollution Control District (SJVUAPCD); state air regulations are
the most stringent ARARs. The applicable regulations are:  Rule 2201 Sec. 4.1 - Best
Available Control Technology; Rule 2201, Sec. 4.2 - Offsets for Stationary Sources; Rule
4101 - Visible Emissions; Rule 4102 - Air Contaminant Discharge; Rule 8010 - Fugitive
Dust; Rule 4201  - Paniculate Matter; and Rule 4202 - Dust and Condensed Fumes. Table 4-
2 contains the applicable or relevant and appropriate sections of these regulations identifying
the ARARs' status and a brief description of the substantive requirements and applicability to
either the site, RA, or technology used to clean up the site and contaminated material.

4.3.2.2  State Groundwater ARARs. The Federal Clean Water Act regulates discharge to
surface waters and groundwater. Under this statute is the 40 CFR 122 - EPA Administrative
Permit Program: NPDES regulation for stormwater and other discharges to surface waters.
This program has been delegated to the state and is a state ARAR.

The CVRWQCB has issued a stormwater NPDES permit for Castle AFB.  It controls
stormwater requirements for this ROD.

The Porter-Cologne Water Quality Control Act establishes the authority of the SWRCB and
the CVRWQCB  to protect the quality of surface water and groundwater. The California
Water Code sections used as a source for action-specific ARARs and TBCs are presented in
Table 4-2 along with the associated regulatory citations.  Under the Porter-Cologne Act, the
following regulations or resolutions regulating and protecting the waters of the state are
considered either applicable or relevant and appropriate (as indicated in Table 4-2) and are
therefore ARARs:  Portions of the Central Valley Region (CVR) Basin Plan which
establishes numerical and narrative water quality objectives to ensure the reasonable
protection of beneficial uses of water; SWRCB Resolution 68-16;-SWRCB Resolution
88-63; and Section IHG of SWRCB Resolution 92-49. Table 4-2 contains the applicable or
relevant and appropriate sections of these regulations identifying the ARAR status and a brief
description of the substantive requirements and applicability to either the site, RA, or
technology used to clean up the site and contaminated material.

SWRCB Resolution 68-16 has been identified as an applicable requirement for the protection
of surface waters and groundwater of the state. The AF and the state do not agree on the full
substantive requirements of this resolution and the impacts on the RA activities needed to
clean up Castle AFB. The AF disagrees with the state's contention that the narrative
language establishes chemical-specific ARARs for both  soils and groundwater, and that
discharges subject to the resolution include post-1968 migration of in situ contamination

                              FINAL RECORD OF DECISION
          CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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31 January 1997

from the vadose zone to groundwater.  The AF believes that discharges encompass only
remedial activities that actively discharge to surface water and groundwater of the state.
However, the remedies selected are intended to control further migration and, therefore,
comply with Resolution 68-16 as interpreted by the RWQCB.

SWRCB Resolution 68-16, the water anti-degradation policy, is a state ARAR for the
establishment of numerical limits for the reinjection of treated groundwater into clean areas
(i.e., high quality waters) of the aquifer, (i.e., outside of the contaminated plume). The
numerical limits established on a monthly median and on a daily maximum basis to meet the
requirements of SWRCB Resolution 68-16 are set forth in Table 4-3. With respect to the
injection of treated groundwater  within the contaminated plume, treatment shall be such that
the concentration level of the contaminant in the injection groundwater must not exceed the
concentration in the groundwater at the point of injection measured on a monthly median
basis, and also not exceed the federal and state ARARs.  With respect to injection of treated
groundwater outside the contaminated plume,  the effluent is required to attain a discharge
level for each constituent measured on a monthly median basis, with the maximum
enforceable discharge standard not to exceed the federal or state ARARs. To meet the
requirement that the selected  remedy be protective of human health and the environment, the
AF shall maintain hydraulic control of the plume while extracting contaminated groundwater
and reinjecting treated groundwater into the contaminant plume or the clean portion of the
aquifer.

SWRCB Resolution 92-49 establishes policies and procedures for the Regional Water
Boards' oversight of investigations and cleanup activities resulting from discharges which
affect or threaten water, including groundwater, quality.  In July 1994, the State Water Board
duly promulgated Resolution 92-49 in accordance with the state's administrative law
requirements to cure defects pertaining to the initial promulgation of the resolution in 1992.
For purposes of Castle AFB groundwater contamination, the regional board is directed by
Resolution 92-49 to apply Section 2550.4 of Title 23T, California Code of Regulations, Div. 3.
Chapter 15, Section 2550.4(e) which requires that any alternate concentration level worse
than background water quality must be the lowest concentration level the discharger can
demonstrate is technologically and economically achievable, but under no circumstances can
the alternate concentration level  be worse than maximum concentrations allowable under
other statutes or regulations.

In September 1995, the Department of Defense (DOD) forwarded a DOD legal position
asserting that no portion of Resolution 92-49 was an ARAR because the same cleanup
standard of Section 2550.4 incorporated into the resolution was found in Section 66264.94 of
Title 22, CCR, Div. 4.5, Chapter 13. Since Section 66264.94 is part of the state's Resource
Conservation and Recovery Act  (RCRA) Subtitle C program as authorized by EPA, Section
66264.94 was a federal ARAR.  Since the cleanup standard incorporated into Resolution 92-
49, Section JUG was not more stringent than the federal ARAR, the federal ARAR is
controlling.

                              FINAL RECORD OF DECISION
          CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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                                                                       31 January 1997
The state disagrees with this position, but has determined that the substantive requirements of
Resolution 92-49 are being met by the RAs.

In addition, the Air Force has agreed to implement the following requirements:

1: [fr. P.5 - Reuse]
2: [fr. P.5 - Policy for investigation]
3: [fr. P.8 - Compilation of WQ goals]

While EPA and the Air Force do not agree that these requirements rise to the definition of
"applicable or relevant and appropriate requirements," the Air Force has nevertheless agreed
to implement these requirements.  The SWRCB's legal position is that the first two
requirements listed above are applicable ARARs since they were promulgated and establishes
criteria and limitations that are more stringent than Federal requirements. The RWQCB
reserves its legal position but the parties agree that the substantive requirements will be
complied with in implementing this ROD.

4.3.2.3  Other State Regulations. The State Fish and Game Code regulates to protect
aquatic life living in the waters of the state. All remedial activities that have the potential of
causing a discharge to any stream, lake, or other body of water must comply with the
requirements of the code.

A sampling and monitoring plan will be prepared in accordance with the ARARs in Table 4-
2. Particular attention should be paid to the requirements listed in Table 4-2 under 40 CFR
122. The following requirements are also TBC.

California Well Standards (California Department of Water Resources [DWR],
Bulletin 74-90, June 1991) and Sacramento County Code, Title 6, Chapter 6.28 - The
California Water Code (Chapters 1152, 1373, and 13801) requires the DWR to establish
standards for the construction, operation, and abandonment of water wells, monitoring wells.
and cathodic protection wells.  Any San Joaquin County-developed well construction
regulations based on authority granted to the county through enforcement of the state
standards should be considered as TBCs for construction of groundwater wells (injection,
extraction, and monitoring).

In addition to these well standards, the guidelines provided by the California Base Closure
Environmental Committee (March 1994) in "Long-Term Groundwater Monitoring
Guidance" are TBCs for:
                             FINAL RECORD OF DECISION
         CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART I

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31 January 1997
•   establishing background groundwater quality;
•   frequency of water level measurements;
•   suite of constituents in the monitoring program;
•   sampling frequency; and
•   inspection and well maintenance.

Several of the California regulations require certification by a professional geologist or
engineer, registered or certified by the State of California. These portions of the regulations
are considered procedural rather than substantive requirements. However, to the degree that
federal contractors perform and/or supervise the engineering and geotechnical work, they will
be certified professionals or under the supervision of certified professionals as appropriate.
                              FINAL RECORD OF DECISION
          CASTLE AIR FORCE BASE COMPREHENSIVE BASEWIDE PROGRAM-PART 1

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          RESPONSIVENESS SUMMARY




        FOR THE PROPOSED PLAN ON THE




COMPREHENSIVE BASEWIDE-PART1 (GROUND WATER)




    CASTLE AIR FORCE BASE (AFB), CALIFORNIA




               JANUARY 31,1997

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                                                            Responsiveness Summary for CB--Part 1
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                                                                                31 January 1997
A. OVERVIEW
At the time of the public comment period, the Air Force had already selected preferred
alternatives for groundwater plumes at Castle Airport (formerly Castle AFB), California. The
Air Force recommended cleanup alternatives for the Main Base and East Base plumes, and
potential presumptive remedies for the East Base and Castle Vista plumes.

The Air Force's recommended alternative for the Main Base Plume specified in the Record of
Decision (ROD) for the Comprehensive Basewide—Part 1 (CB--Part 1) involved pumping and
treating groundwater with two systems, one ongoing (operable unit 1 [OU-1]) and one planned
(OU-2). As part of the preferred alternatives, a phased approach was chosen as a clean up
program for groundwater at Castle Airport. The phased approach consists of three sequential
phases of pump-and-treat groundwater remediation.  The three phases were established in order
to allow for the collection and use of information from technical effectiveness studies of OU-1
and OU-2 systems, as well as other studies (e.g., long-term monitoring).  The phases are
explained below:

        Phase 1:  The first phase will take advantage of existing OU 1 treatment capacity, to expand the
        treatment of groundwater in the OU 1 area to remove TCE and control migration of TCE "hot spots"
        in the shallow groundwater zone of OU 1.  This will be accomplished by expanding the OU 1
        extraction system through installation of new extraction wells in the shallow groundwater zone.
        Granular Activated Carbon (GAC) and/or air stripping groundwater treatment systems will be utilized
        to achieve treated water release levels stipulated in this ROD.  Design of the OU 1 expansion will be
        included in the ongoing effort known as the Revised Basis of Design Report. In addition, the OU 2
        groundwater extraction network that is planned will be completed and operations initiated.

        Phase 2:  Phase 2 will enhance the OU 1 extraction network to a multiple groundwater zone
        remediation system with the addition of extraction wells and the utilization of GAC or air stripper
        treatment systems to achieve effluent release levels. AVater reuse study will be conducted to
        determine the most appropriate combination of reinjection, canal discharge, and water reuse to be
        utilized for the disposal of treated groundwater. Pump tests will be conducted to obtain necessary
        hydrologic information on groundwater zone properties.                -

        Phase 3:  Data collected from the first two phases will be evaluated and a Phase 3 Technical
        Evaluation and Design Study will be prepared to determine what additional wells will be needed to
        achieve the overall cleanup objectives.  By the onset of Phase 3, both Phase 1 and 2 pump and treat
        systems will  have been installed, data gap wells and the Long-term Groundwater Sampling Program
        network will be in place, pump tests will have been evaluated, and the flow and transport models will
        have been updated.  That information will facilitate better predictions of the hydraulic control of the
        groundwater zones and plume remediation time periods, and will provide the basis for design
        decisions regarding Phase 3 expansion of the groundwater remediation system.

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                                                                        31 January 1997

The recommended cleanup action for the East Base Plume involves the sealing and abandonment
of wells to prevent further cross contamination of groundwater zones. Monitoring will also be
accomplished to develop a more complete definition of the plume and to determine the need for
active remediation. Evaluation of the data collected during monitoring will be summarized as
part of the Technical Evaluation and Design Report, which will be developed during Phase 2 of
CD-Part 1 Remedial Design/Remedial Action.  If this evaluation indicates further active
remediation is required, pump-and-treat technology would be available as the presumptive
remedy and this additional action will be integrated into Phase 3.

Detailed analysis was not conducted for the Castle Vista Plume; however, it is recognized that
additional data collection is underway to better characterize this area.  In the event additional data
collected during monitoring events indicates the need for active groundwater cleanup, the pump-
and-treat approach would be available as the presumptive remedy.  Evaluation and
implementation of this additional action will be integrated as appropriate into Phase 3 of the CB-
-Part 1 Remedial Design/Remedial Action.

Judging from the comments received during the public comment period, the community
surrounding Castle Airport supports the pump-and-treat system recommended for the Main Base
Plume. However, the community prefers more proactive cleanup actions for the East Base and
Castle Vista plumes (such as pump-and-treat) than indicated in the draft ROD for CB—Part 1 as
the selected remedies/actions for these plumes.

These sections follow:

•  Background on Community Involvement

•  Summary of Comments Received During the Public Comment Period and Air Force
   Responses

•  Remaining Concerns

•  Attachment A:  Community Relations Activities at Castle Airport
B.  BACKGROUND ON COMMUNITY INVOLVEMENT

Community interest in groundwater at Castle Airport dates to February 1978, when the base
commander notified workers and residents at Castle Air Force Base that trichloroethylene (TCE)
was above the 5 parts per billion state action level, and required the boiling and use of bottled
water at the base hospital and all food-serving establishments. In late February, the state
Regional Water Quality Control Board formally ordered Castle Air Force Base to clean the TCE
out of the base water and neighboring property. On-going community concern, generated by the
clean-up order, dissipated when work was completed on a new TCE-free well in February 1985.

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                                                       Responsiveness Summary for CB—Part 1
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                                                                         31 January 1997

In November 1985, residents immediately affected by groundwater contamination expressed
concern about its effect on their health and property when TCE contamination above the 5 parts
per billion action limit was found in two of the three off-base wells at Castle Mobile Home Park.
In response to this discovery, the base began supplying bottled water to park residents until
activated carbon filtration systems could be  installed. Residents were connected to City of
Atwater water supply in March 1989.

By 1990, City of Atwater residents demonstrated little interest in the groundwater problem.  Part
of this was attributed to lack of knowledge about the restoration program, although a strong
community relations program had been in place addressing specific contamination problems
experienced at Castle  Air Force Base.  Additionally, City of Atwater residents were served by a
municipal  water source, which was unaffected by the contamination and closely supervised by
the state and local governments.

Community concerns and involvement have remained strong to date. The major concerns
expressed  during the remedial planning activities by property owners, interested groups, and
local officials involve: the possible health effects from contamination at the site; the amount of
funding needed for cleanup; and the Air Force's commitment to Castle's remediation which
could take 16 to 20 years.  These concerns and how the Air Force addressed them are described
below:

1) What are the health effects and risks associated with drinking, cooking, and bathing in water
contaminated with TCE in various concentrations?

Air Force response:  TCE is a chemical of concern identified by EPA in the early 1980s,
thus drinking water standards have been set at 5 micro grams per liter and drinking water
has been kept below this level. Where TCE has reached or exceeded this level in private
wells in the area, the Air Force has installed and maintained individual filter systems or
provided an alternate drinking water source.

2) Could funding be cut off before the base has been cleaned up?

Air Force response:  Funds for cleanup are programmed and will be included in the annual
funding request to congress.  We do not attempt to predict what congress will do nor
obligate them in any way; but history has shown that proper programming gets adequate
results.

3) Will the Air Force continue cleanup after they leave the base in 1995?

Air Force response:  Yes, the Air Force has formed the Air Force Base Conversion Agency
(AFBCA) to do just that We are part of that agency and plan to remain until the job is
done.

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                                                     Responsiveness Summary for CB~Pan 1
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                                                                      31 January 1997


4) Will the plume on base move and destroy my crops?

Air Force response: We have no evidence of TCE affecting crops in any way.

5) Why does the cleanup take so long?

Air Force response: Three reasons: (1) Thorough studies are required to identify the total
nature and extent, and potential impact(s) contaminants from the base may have on human
health or the environment (2) Cleanup timeframes are at the mercy of mother nature. It
took the Air Force almost fifty years to effectuate the soil and groundwater problems that
exist today. It may take that long for mother nature to give it back. Groundwater clean
ups are generally slow. (3) The Air Force wants to thoroughly coordinate action(s) so
problems are not created for others and reuse/economic redevelopement can  occur as soon
as possible.

6) How will TCE in the groundwater affect the City of Merced?

Air Force response: Data indicates TCE from Castle AFB does not have the potential to
affect Merced directly.

Recently, the Restoration Advisory Board (RAB) has been particularly vocal in expressing the
concerns of the community to the United States Environmental Protection Agency (EPA),
Regional Water Quality Control Board, Department of Toxic Substances Control, and Air Force
(Base Conversion Agency). They have been successful in changing the ROD to include primary
and secondary remedial options for the East Base and Castle Vista plumes. The choice of
options will be contingent upon evaluated data received during monitoring of the plumes.  The
Air Force has been active in disseminating information concerning the  groundwater
contamination at Castle Airport to the surrounding community. A chronological list of
community relations activities concerning groundwatei*at Castle Airport that has been conducted
by the Air Force is presented in Attachment A.


C. SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC
    COMMENT PERIOD AND AIR FORCE RESPONSE

The public comment period on the draft Feasibility Study and proposed plan for CB—Part 1 was
held from June 25, 1996, to August 25, 1996. Comments received during this time are
summarized below and are categorized by remedial alternative preferences, technical comments,
human health concerns, and public participation process. Most comments were received during
the public meeting, where the only local citizens in attendance were RAB members. Other
comments were received in writing from Merced County, Division of Environmental Health,
California Central Regional Water Quality Control Board, and Department of Toxic Substances
Control.

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                                                     Responsiveness Summary for CB—Part 1
                                                                         Page 5 of 12
                                                                      31 January 1997
Remedial Alternative Preferences and Other Technical Comments

(1) A RAB member questioned the identity of the contaminants in the East Base Plume. The
member also expressed concern that the contaminants may not be affected or corrected by the
East Base Plume preferred alternative presented in the proposed plan.

Air Force Response:  As stated in the Proposed Plan for CB-Part 1 (page 7, Table 1) the
principal contaminant identified for the East Base Plume is trichloroethylene (TCE) and it
is only found in the shallow groundwater zone. When compared to the Main Base Plume,
which contains 98 percent (by weight) of the TCE contamination at Castle Airport, the
East Base Plume only contains 1.8 percent (by weight) of TCE contamination, the East
Base Plume is minor both in concentration and distribution.  However, wells in and
downgradient from the East Base Plume will continue to be monitored on a quarterly basis
to ensure that contamination does not increase to levels of concern for human  health and
the environment  When and if the data indicates that the contamination has increased
substantially, a presumptive remedy (i.e., pump-and-treat groundwater) exists as a
secondary option for the East Base Plume. Data is continually being collected, analyzed,
and evaluated for all the plumes at Castle Airport.

(2) A RAB member is concerned that the balancing criteria (e.g., long-term effectiveness)
indicates that the selected alternative in the proposed plan for the East Base Plume  may not solve
all the problems associated with the contamination.  More specifically, the proposed plan states
that Alternative 2, Well Destruction and Monitoring (proposed remedy for East Base Plume),
may not comply  with all the groundwater protection standards and does not reduce  the extent of
groundwater contamination, but will stop the potential movement of additional contamination.

Air Force Response:  Long-term effectiveness of the selected remedy does not apply
because the preferred alternative will not physically remove the contamination. Since data
indicates a small percentage of contamination (1.8 percent) when compared to the Main
Base Plume (98 percent), it is assumed that natural processes (i.e., natural attenuation) will
reduce the contaminants over time. The preferred alternative will reduce the  potential of
introducing additional contamination into deeper, uncontaminated groundwater zones.

(3) A RAB member questioned if the EPA agrees that the ROD contains contingency language
that provide for two possible options (a primary and secondary option) for the East Base Plume.

Air Force Response:  At the public meeting for CB-Part 1, an EPA representative agreed
that the ROD should specify two remedial alternative options for the East Base Plume.
Contingency language will be stated hi the ROD for a primary remedial option (well
destruction and monitoring), and a secondary remedial option (pump-and-treat) for the
East Base Plume. The Air Force will continue to collect, analyze, and evaluate data from
monitoring wells at the East Base Plume. Evaluation of the data collected during
monitoring will be summarized as part of the Technical Evaluation and Design Report  If

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                                                     Responsiveness Summary for CB-Part 1
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                                                                       31 January 1997

data indicates something more than monitoring is required, the community will be
consulted for installation of a pump-and-treat system. However, if data indicates that the
plume is stable or decreasing in aerial extent, monitoring will continue.

(4) A RAB member is concerned about the two potential options chosen for the East Base
Plume. The member stated that it would be "more comfortable" if Alternative 4, pump-and-treat,
was chosen as the primary option instead of Alternative 2, Well Destruction and Monitoring.
The member continued that if data gaps warrant, the Air Force could downgrade to the less
conservative option (Alternative 2), instead of upgrading to the more conservative option
(Alternative 4).

Air Force Response:  The Regional Water Quality Control Board, California EPA, and
Department of Toxic Substances Control entered discussions with this proposition; but the
Air Force was able to convince these regulatory agencies that their charter is to protect
you (i.e. the community) in these matters and because the plume is minor in both
concentration and distribution and that active remediation could provide pathways for
deeper contamination; therefore maximum protection is attained with Alternative 2 using
Alternative 4 as a backup.

(5) A RAB member questioned if federal, state, and local agencies approved of the proposed
plan's selected remedy for the East Base Plume (Alternative 2)

Air Force Response:  The agencies are in agreement with the Air Force on the preferred
alternative selected for the Main Base Plume. However, a professional difference exists
between the Air Force and the agencies on the East Base and Castle Vista plumes. There
are two contingent options (primary and secondary) available for each of these plumes:
well destruction and monitoring, and pump-and-treat as a presumptive remedy for the
East Base Plume; and No Further Action and pump-and-treat as a presumptive remedy for
the Castle Vista Plume.  The agencies prefer the pump-and-treat alternative as the primary
remedy for the plumes and the Air Force prefers the weU destruction and monitoring and
No Further Action as the primary remedies for the East Base and Castle Vista plumes,
respectively.  However, both the Air Force and the agencies agree that further evaluation of
the data currently being collected at both plumes may indicate implementation of other
than the preferred option at either plume.

(6) The Merced County Department of Public Health recommends surface recharge basins for
the Merced Irrigation District (MID) as an additional discharge option other than reinjection
wells and existing irrigation canal.

Air Force Response: The Air Force will address the possibility of surface recharge basins
as a disposal option in a Water Reuse Plan to be prepared in late 1996.

(7) The Regional Water Control Board and Department of Toxic Substances Control
recommended that the report described in Phase 3 of the preferred alternative for the Main Base

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                                                      Responsiveness Summary for CB—Part 1
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                                                                       31 January 1997

Plume be entitled Technical Evaluation and Design Report  The EPA stated that the purpose of
Phase 3 is not to conduct an economic study but to evaluate the data from the previous two
phases and incorporate that evaluation into the report.

Air Force Response:  The Air Force agrees that the document to be prepared on Phase 3
for the Main Base Plume should be entitled "Technical Evaluation and Design Report."
The document will establish the baseline and format of the five year review reports as well
as summarize the data evaluated in the first two phases.

(8) The Regional Water Control Board and Department of Toxic Substances Control disagree
with the preferred alternative of No Further Action with a presumptive remedy in the event that it
is necessary. The action acceptable to the state for the Castle Vista Plume is the presumptive
remedy consisting of pump, treat, and data collection unless or until it is demonstrated that the
plume is small. In addition, the agencies state that the existing technology [No Further Action] is
not cost effective nor is it believed to offer acceleration of clean up beyond that which will occur
by natural attenuation.

Air Force Response:  The Air Force agrees that revaluation of existing data and the
collection of additional data is in order prior to a final decision. The Air Force is collecting
additional information in an attempt to characterize the nature and extent of the
groundwater contamination in the area of Castle Vista housing.
                              i
(9) A RAB member questioned the acceptable level of contamination and how migration of the
plume is determined?  Furthermore, the RAB member questioned, "Will the plume migrate and
gradually dilute itself to the point where it is not a problem"?

Air Force Response:  Currently the Maximum Contaminant Level (MCL) for TCE is 5
micrograms per liter or parts per billion. This level has been established by regulatory
authority. The migration of a plume is determined by placing monitoring wells in strategic
locations on and downgradient with respect to the plume. After analyzing and evaluating
groundwater sampling data received from the wells, computer models are used to
determine if, how fast, and which direction groundwater is migrating (moving). The
migration and dilution of the plume as well as natural attenuation (various natural forces
are effective in eliminating contamination) are evaluated. In addition, the data from
samples taken during monitoring events is evaluated.  If information indicates that the
plume is stable and the mass is small, the Air Force will continue monitoring. Monitoring
will continue unless the data indicate the plume is increasing in concentration and/or aerial
extent at which point the presumptive remedy will be implemented.

(10)  A RAB member questioned, after installing a well on adjacent property, if pumping from
the well would have adverse effects on the plume.

Air Force Response:  The affect of pumping from a potential new well on a contaminant
plume would be part of the evaluation stated in the Air Force response to question 16.

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                                                      Responsiveness Summary for CB—Part 1
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                                                                       31 January 1997

Technically, pumping from wells creates a cone of depression where groundwater flows
towards the well. The shape of the depression depends on many factors including soils,
amount of pumpage (e.g., gallons per minute), groundwater flow rate and direction, type of
aquifer (i.e., confined), and hydrogeplogic boundaries, including the edge of an aquifer and
a source of recharge (i.e^ stream or lake). Pumping on a new well could impact the existing
plume based on specific conditions of the new well and the plume.

(11) A RAB member is concerned with the computer model/plan that set up extraction wells
locations for OU-1 system. In addition, the member is disappointed with the well procurement
system that has occurred for the last two years.

Air Force Response:  The Air Force would refer to question 9 because modeling
(mathematical simulation) is more an art than a science. Again, experts check experts and
the Air Force uses the model to help make decisions.

(12) A RAB member questioned if any data from MID on strata and water flow was used when
choosing well locations for the OU-2 system.

Air Force Response:  The experts and the checking experts used data from every source.
The fear of every review panel is that local information will appear to detract from their
expert reputation; therefore, great care to gloss the last bit of data is exercised. This is a
contributing factor to the time it takes to do a thorough evaluation of underground
remediation efforts.

(13) A RAB member questioned the timeline for drilling additional wells for the East Base
Plume.

Air Force Response:  The Air Force has no formal timeline for this effort

(14) A RAB member questioned if data gaps from welts on the East Base and Castle Vista
plumes will be completed within the 30-day public comment extension (ending August 25,
1996). Furthermore, the RAB member wanted to know what "the timeline was on finishing the
data gaps.

Air Force Response:  The timeline for the data was within the 30 day period and the
secondary option was identified as preferred for the Castle Vista Plume.

(15) A RAB member is concerned that the Installation Restoration Program process (i.e.,
completing the ROD) is continuing with incomplete information/data.

Air Force Response: Since information/data is continually being collected, it is the Air
Force's proactive decision to begin cleanup of the plumes where data currently indicates a
contamination exists above regulatory limits. Data is collected, analyzed, and evaluated
quarterly. The evaluated data in conjunction with the contingency of primary and

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                                                     Responsiveness Summary for CB-Part 1
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                                                                      31 January 1997

secondary options, stated in the ROD for the East Base and Castle Vista plumes, will
ensure that groundwater contamination is addressed without an undue expense to the Air
Force and indirectly tax payers.

Contaminants Impact on Human Health Concerns

(16)  A RAB member questioned the impact of groundwater contamination on a potential
irrigation well to be installed on adjacent land.

Air Force Response: Any individual installing a well in Merced County must obtain a
permit from the county. Subsequently, the Ah* Force hi conjunction with the county or
MID will evaluate the potential impact of the well on the plume. Then the Air Force, the
county, and the landowner would determine if the location of well, the rate of pumpage,
and the depth of the well is acceptable.

(17)  The above response prompted a RAB member to question if the Air Force has an agreement
with  the Public Health Department to evaluate the adjoining property owners when they apply for
permits to drill.

Air Force Response: The Merced County Public Health Department is aware of Castle
Airport's contamination problem. The Merced County Public Health Department would
seek the Air Force's assistance in making sure that the well would not be affected by any
plumes at Castle Airport

(18) A RAB member is concerned  about plumes that are migrating into other areas, such as the
Castle Vista Plume. The member is also concerned that there has been additional findings of
contaminants in that area.

Air Force Response: The Air Force is also concerned and thus data is being collected.
(The data has indicated the need for a pump and treat system for this plume.)

(19)  The Department of Public Health commented that the TCE problem in the private wells
located at 4460 and 4472 Buckeye  Lane are not addressed in the proposed plan for CB—Part 1 /  -

Air Force Response: These wells are outside our normal monitoring zone. These wells
were sampled at the request of the RAB along with several others. TCE concentrations
well below drinking water standards  were encountered at these two wells; but no action is
required at this time. Monitoring through the long term groundwater sampling program
will continue and if changes occur the county will notify the property owners.

Public Participation Process

(20)  A RAB member is concerned that the MID had not been contacted after a suggestion by a
member, at a previous RAB meeting, was made to coordinate with the MID. The member was

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                                                                      31 January 1997

assured by the Air Force that MID was involved in the cleanup process at Castle Airport  In
addition, the RAB member stated that water is not pumped from an underground pond, but from
strata. The RAB member continued, "MED has extensive information on water strata in the
whole area; in fact, there's a comprehensive program going on between the City of Merced,
Atwater, and Livingston to insure that there will be water hi this area into the future."

Air Force Response:  Air Force personnel have coordinated and worked with MID
engineering staff over the years. The Air Force and MID have existing agreements in
regards to monitoring wells along MID easements and rights of way etc. Base personnel
did contact the MID when the Hydrotech memo for the Operable Memo 2 was prepared.
The memo documents the conversation with MID. The-point ofcontact  at MID for the     -
Hydrotech memo was Mr. Eric Abramson. MID and Air Force coordination was extensive
during the initial comprehensive surrounding pumping well survey conducted in 1989.
MID engineering staff have coordinated with the Air Force regarding the comprehensive
planning effort underway. Air Force will continue coordinating with MID as appropriate.
(21) A RAB member questioned community participation with respect to determining what type
of program or alternative is going to be used to mitigate problems that exist at Castle Airport.
The member additionally stated, "Just as we address the questions today and that they will be
given back to us by letter, or whatever, we have no assurances that these concerns are going to be
used in altering any decisions that you make." The member is concerned that if the plan is
"solidified" and the community does not make an impact, it will be more and more difficult to
make an impact in the future.

Air Force Response: The community is continually kept informed of the Installation
Restoration Program occurring at Castle Airport  Major community relations activities
include the distribution of fact sheets and news letters, tours of the sites at Castle Airport,
and communication during RAB meetings. The community's concerns are requested,
evaluated, considered, and recorded in this Responsiveness Summary.  However, when
determining the selected remedy for a site, the community is just one of the participants in
the decision making process; other participants include local entities, state agencies, EPA,
and Air Force. Further, with differing opinions and solutions the Air Force must select the- •
solution it thinks best and proceed in the interest of all participants.

(22) A RAB member questioned the latest date the community could comment on the proposed
plan for CD-Part 1 and could the community obtain an extension of the public comment period.

Air Force Response: The initial 30-day comment period ended on July 25,1996. A
community member can obtain a 30-day extension of the public comment period by an oral
statement requesting an extension.

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                                                     Responsiveness Summary for CB—Part 1
                                                                       Page 11 of 12
                                                                      31 January 1997

(23)  A RAB member expressed the intent of a public meeting is to have the community express
their concerns and to have those concerns mean something, and to have that elated into the
decision-making process.

Air Force Response: Prior to signing the ROD, all comments and additional data received
subsequent to the preparation of the proposed plan will be evaluated and considered.
Subsequent to the evaluation of comments and data, the ROD will be finalized and signed
by the EPA, California EPA, and Air Force Base Conversion Agency.  The signed final
ROD will enable remedial work to begin on the subject sites or operable units.

After the ROD is signed, new information may be generated during the Remedial
Design/Remedial .Action process that could affect the remedy selected in the ROD. The Air
Force will analyze the new information to determine if changes should be made to the
selected remedy. Three types of changes could occur:  non-significant changes, significant
changes, or fundamental changes. If non-significant changes are made, they will be
recorded in the post-decision document file; if significant changes are made to a component
of the remedy in the ROD, these changes will be documented in an Explanation of
Significant  Differences; and if fundamental changes are made to the overall remedy, these
changes should be documented in a ROD amendment. All changes will be reviewed at
regular RAB meetings as well as at Public Hearings when required.

(24)  A RAB member asked why community acceptance was number nine of the evaluation
criteria presented in the proposed plan for CB—Part 1. In addition, the member asked why only
the first seven criteria where considered during the evaluation.

Air Force Response: The evaluation criteria are not in order of priority. The first seven
criteria are evaluated in the feasibility study, the phase of project progress we are now in.
The draft final is issued for state and community comment and as an integral and continual
part of the Installation Restoration Program process, from the assessment phase of the
process through the remedial phase, these comments are addressed.

(25) A RAB member stated that based on the community concerns on the East Base and Castle
Vista plumes, the member asked for a 30-day extension of the public comment period.  The
member continued that the extension would allow the RAB and the people in the community to
have an opportunity to make impacts that they feel necessary and to insure  that the decision is
made in a way that will benefit the community.

Air Force Response: The public comment period started on June 25,1996. During the
comment period, the Air Force held a public meeting on July 23,1996, to receive any
questions on the Proposed Plan. The comment period initially allowed 30 days to comment,
but was extended to allow.an additional 30 days. With the extension, the comment period
ended on August 25,1996, but if there are any comments tonight (August 27,1996) we will
accept them.

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                                                      Responsiveness Summary for CB—Part 1
                                                                         Page 12 of 12
                                                                       31 January 1997
D.  REMAINING CONCERNS
Issues and concerns that the Air Force was unable to address during remedial planning activities
include the following:

(1)  RAB members had concerns regarding the landfills at Castle Airport.

(2)  The Department of Public Health commented that the cleanup of leaking underground
storage tanks sites, which are not in the TCE plume areas, are not addressed in the proposed plan
forCB-Part 1.

(3)  The Department of Public Health questioned if the recommendations of the Lawrence
Livermore Report will be used in the cleanup of petroleum contaminated sites.

Air Force Response to above three concerns: These issues are not related to groundwater
at Castle Airport. The Air Force will hold a 30-day comment period and public meeting on
the Source Control Operable Unit (SCOU) after completion of the Remedial
Investigation/Feasibility Study for the SCOU to allow the public to voice their questions
and concerns regarding the sources of contamination at Castle Airport

(4)  A RAB member is concerned that contamination is leaking into the ground and the Air Force
is putting soil and grass on top of it, and then is pumping the water for the next  100 years. In the
meantime, the RAB member indicates, the contaminants are continually leaking into the
groundwater.

Air Force Response: The major sources of contamination at Castle Airport have remedial
activities in operation or planned (i.e., bioventing, soil vapor extraction). Since this
comment is more relevant to the sources of contamination (i.e., SCOU activities), it will be
fully responded to during the SCOU public comment period. This may be a perception,
and as such must be addressed.  Water is being pumped to treat groundwater that is
already contaminated.  When contamination above standards reaches groundwater it must
be removed before it affects citizens. To protect the groundwater after it has been cleaned
surface (soil) actions must be taken.  These actions generally intercept the pathways
contaminants take to get to the groundwater and provide seals to the atmosphere so that
soil gases can be extracted and treated accelerating remediation. The Air Force is
dedicated to taking these actions where needed and not taking action where it is not
needed. We are not perfect, stay with us, help us in our decisions  and together we will
accomplish cleanup at Castle in a beneficial manner.

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              ATTACHMENT A



                  TO THE




        RESPONSIVENESS SUMMARY FOR



COMPREHENSIVE BASEWIDE-PART1 (GROUNDWATER)








      COMMUNITY RELATIONS ACTIVITIES




         AT CASTLE AIR FORCE BASE

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                                 ATTACHMENT A

                     COMMUNITY RELATIONS ACTIVITIES
                              AT CASTLE AIRPORT

Community relations activities conducted at Castle Airport regarding Comprehensive Basewide-
Part 1 (e.g., groundwater) activities have included:

•   The Air Force conducted interviews with community leaders and interested residents of the
    cities of Atwater and Merced, and Merced County (May 16,1988).
•   The Air Force developed an environmental mailing list (1988). The mailing list is updated on
    a monthly basis.
•   The Air Force prepared a Community Relations Plan (1990).
•   The Air Force established an Information Repository at the Merced County Library (1990).
•   The Air Force conducted interviews with local community officials, residents, and business
    people (August/September, 1994).
•   The Air Force revised the Community Relations Plan (1994).
•   The Air Force developed the Restoration Advisory Board (April 22, 1994). Meetings are held
    every other month to inform the local community of Castle Airport's cleanup and reuse
    efforts.
•   The Air Force conducted interviews with local property owners, a Restoration Advisory
    Board member, government officials, and a representative from the Sierra Club (March,
    1995).
•   The Air Force updated the Information Repository (1995).
•   The Air Force prepared and distributed a fact sheet entitled, "Air Stripping and Granular
    Activated Carbon (GAC) Treatment Technologies"  (March, 1995).
•   The Air Force prepared and distributed a fact sheet entitled, "Information Repository"  (June,
    1995).
•   The Air Force prepared and distributed a fact sheet entitled, "Base Conversion Process"
    (June, 1995).                                 *
•   The Air Force revised the Community Relations Plan (1995).
•   The Air Force prepared and distributed a fact sheet entitled, "Risk Assessment" (November,
    1995).
•   The Air Force conducted interviews with the representatives from the Merced Board of
    Supervisors, Merced Irrigation District, and Merced County Economic Development
    Corporation, and concerned citizens (January, 1996).
•   The Air Force prepared and distributed a fact sheet entitled, "Environmental Laws Affecting
    IRP" (February, 1996).
•   The Air Force prepared and distributed a fact sheet entitled, "Castle Airport IRP Sites" (June,
    1996).
•   The Air Force conducted a tour of various sites at Castle Airport (1996).
•   The Air Force prepared and distributed a fact sheet entitled, "Trichloroethylene" (April,
    1996).
                                         A-l

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                          ATTACHMENT A
                              (completed)

               COMMUNITY RELATIONS ACTIVITIES
                        AT CASTLE AIRPORT

The Air Force revised the Community Relations Plan (June, 1996).
The Air Force held a public hearing at the Atwater City Council Chambers to record
comments by the public (July 23, 1996). A transcript of this meeting is available at the
Merced County Library.
The Air Force extended the public comment period.  The comment period was held-from June-
25 to August 25, 1996.
                                 A-2

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              ATTACHMENT B

                 TO THE

        RESPONSIVENESS SUMMARY FOR

COMPREHENSIVE BASEWTOE--PART 1 (GROUNDWATER)
      RESPONSE TO AGENCY COMMENTS
                   ON
 PRELIMINARY AND DRAFT RECORD OF DECISION
                       Or'
         AT CASTLE AIR FORCE BASE

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                                                        DRAFT RESPON3BFTO COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                       11/15/96
DTSC-G-1.
General
The selected remedy for Main Base, East Base, and Castle
Vista Plumes should contain language for institutional controls
(deed restrictions) to prohibit the installation of domestic or
agricultural wells or any well that might interfere with the
groundwater treatment and protect the user of the new well.
Institutional controls, jn addition to active remedial actions, were
not specifically included in the RI/FS recommendations nor the
Proposed Plan. However, a footnote has been added to Table 2-1
indicating that administrative controls in addition to the active
remediation will be implemented as necessary.	
DTSC-S-1.
PageS,
Section 2.4.1
Selected
Remedy: Main
Base Plume,
Phase 1
Second to the last sentence. Please replace with "Design of the
Operable Unit 1 expansion is included in the ongoing effort
known as the Revised Basis of Design Report."
Recommended text change has been made.
DTSC-S-2.
Page 5,
Section 2.4.1
Selected
Remedy: Main
Base Plume,
Phase 3
Detailed time lines for Phase 3 should be included in this
section. Dates for the submittal of the Evaluation and Design
Study Report and the expansion of the groundwater
remediation system should be included. The proposed dates
should be discussed and agreed upon by the agencies prior to
finalizing the Record of Decision (ROD).	
Additional text describing time lines has been incorporated.
DTSC-S-3.
Page 6,
Section 2.4.3,
Selected
Remedy:
Castle Vista
Plume
The text states that the remedial action for the Castle Vista
Plume will be:integrated into Phase 3 of the Comprehensive
Basewide (CB) - Part 1 Remedial Design/Remedial Action.
Please provide the reasoning for conducting the remedial
action during Phase 3.
The integration of Castle Vista Plume remediation into Phase 3 is
for reasons of operational and reporting convenience.  Text has been
modified to provide clarification.
DTSC-S-4.
Section 2.4
Description of
the Remedy
This section is missing a subsection on the discussion of "other
plumes." We suggest that a Section 2.4.4 be added with a title
of "Selected Remedy: Other Plumes." Using the language in
the last paragraph of Page 65 will satisfy.	
Text changes have been made as suggested.
                                                                     Page 1 of 20

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                                                         DRAFT RESPONSES TO COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                        11/15/96
 DTSC-S-5.
 Page 18,
 Section 3.5,
 Nature and
 Extent of
 Groundwater
 Contamination
 Third paragraph. The text should be revised to state that the
 third plume of the East Base Plume under Buildings 1762 and
 1709 has been incorporated as part of the Main Base Plume
 and selected remedy for this Plume is Alternative 3, same as
 Main Base Alternative.
 Text changes have been made as suggested.
 DTSC-S-6.
 Page 31,
 Section 3.6.2,
 Ecological
 Risk
 Assessment
First paragraph, last sentence. Please revise the text to state
when the Phase II Expedited Response Action will be
completed.
Text has been updated as requested.
DTSC-S-7.
Page 35,
Section
3.6.3.4,
Landfill 4
Plume Region
Per our discussion at Castle Air Force Base (AFB), please
revise this section to state that the listed chemicals will remain
as Chemicals of Concern (COCs) even though PRAOs were
not defined.

Last paragraph. The text states "there are no COCs for
Landfill 4 Plume  Region based on these results. Therefore, no
remedial actions are considered necessary for the Landfill 4
Plume and no PRAOs are defined." This statement is
incorrect As discussed in previous meetings, the rationale for
not selecting a remedial action is the predicted high cost and
the little benefit obtained for removing small amounts of
contamination from the groundwater.	
This section has been revised to indicate the correct rationale for
dropping this plume from active remediation (i.e., the high cost and
little benefit obtained for removing small amounts of contamination
from the groundwater).  COC discussion has been modified
accordingly.
DTSC-S-8.
Page 35,
Section
3.6.3.6,
Landfill 1
Plume Region
First paragraph, last sentence. Please revise the last sentence
to state "No active remediation was selected for following
consideration."
Text has been revised to state: "No active remediation was selected
based on the following factors."       ,
                                                                     Page 2^2
                                                               20

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                                                         DRAFTRESPOfJiKo COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                        11/15/96
DTSC-S-9.
 Page 35,
 Section
 3.6.3.7, Castle
 Vista Plume
 Region
 Last paragraph. This paragraph confuses the reader as it does
 not provide a clear rationale for reaching the final conclusion.
 First, in the second sentence, it states that no active remedial
 actions are recommended and no PRAOs are defined and the
 following sentence, it states that the selected remedial
 approach is to pump and treat.

 We suggest that this paragraph be rewritten. It should clearly
 state that the Remedial Investigation/Feasibility Study and
 Proposed Plan recommended no further action with the
 installation of additional wells. It should also discuss the
 sampling results from the new monitoring well which showed
 that the Plume is larger than originally believed and hence
 pump and treat was selected as the remedial action.
 Additionally, listTrichloroethylene as a COC and list the
 PRAO for cis-1,2-Dichloroetnylene.	
The paragraph has been rewritten and additional text has been
included to further describe the basis for remediation of Castle Vista
plume.
DTSC-S-10.
Page 64,
Section
3.8.3.3,
selected
remedy, Phase
3
First paragraph. Please revise the first sentence to read "Data
collected from the first two phases will be evaluated and a
Phase 3 Technical and Evaluation and Design Study will be
prepared to determine what additional wells will be needed to
achieve the overall cleanup objectives."
Text has been modified to state "Data collected from the first two
phases will be evaluated and a Phase 3 Technical Evaluation and
Design Study will be prepared to determine what additional
remedial actions will be needed to achieve the overall cleanup
objectives."
DTSC-S-11.
Page 65,
Section
3.8.3.3.,
Selected
remedy, East
Base Plume
The text states that the Air Force will reassess the need for
active remediation/ It is not clear if the reassessment will be
conducted as part of the LTOSP. If this is the case, then the
LTGSP must be modified to present the criteria used for the
reassessment. Additionally, the criteria must be agreed upon
by the agencies and included as an attachment to the ROD.
The text states that the reassessment will be done under the LTGSP.
The basis for these reassessments is also stated in the present text,
developed based on agency input and response to comments on the
Preliminary Draft ROD.               ,
DTSC-S-12.
Tab 3, Page 2,
Draft
responsiveness
summary
Second paragraph. The text states "In the event additional data
collected during monitoring events indicates the need for
active groundwater cleanup, the pump and treat approach
would be available as the presumptive remedy." This
paragraph should be rewritten to state that the AFB will
actively pump and treat groundwater.	
Text has been changed in accordance with comment.
                                                                      Page 3 of 20

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                                                        DRAFT RESPONSES TO COMMENTS ON
                                                            FINAL DRAFT CB-PART1 ROD
                                                                       11/15/96
DTSC-S-13.
                Tab 7, Table
                4.2, action
                specific
                Applicable or
                Relevant and
                Appropriate
                Requirement
                (ARARs),
                Pagel
                Second ARAR. California Hazardous Waste Control Law.
                The column under the description of ARARs incorrectly
                defines the ARAR standards as either applicable or relevant
                and appropriate. The correct description of the standard
                should be "applicable" as listed under the ARAR Status
                column.
                                                          Table has been changed in accordance with comment.
                                                                                        Substantial changes to the ARARs section (Section 4) have been
                                                                                        considered through additional discussions between the Air Force
                                                                                        and the Regulatory Agency representatives. As a result of these
                                                                                        discussions, agreed-upon modifications to the text have been
                                                                                        incorporated.
DTSC-S-14.
Page 76,
Section
4.3.2.4, Other
State
Regulations
The last paragraph states that the California regulations
requiring a certification by a professional geologist or engineer
registered or certified by the State of California are considered
procedural rather than substantive requirements. Department
of Toxic Substance Control considers registration or
certification by the State of California is a substantive
requirement However, we agree that the CB-Part 1 ROD does
not need to be certified since it does not provide a new
information requiring review by a professional geologist or
engineer.	
                                                                    Page4jif20

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                                                       DRAFTRESPOlfi&O COMMENTS ON
                                                           FINAL DRAFT CB-PART1 ROD
                                                                      11/15/96
RWQCB-I.
Section 4
The ARARs Table 4-2 is incomplete. Many of Board's
ARARs are missing from this table and the description of
others are inadequate or incorrect. Attached is a table listing
missing ARARs (Attachment 1) which should be added to
Table 4-2, with the descriptions of the requirements. The Air
Force should modify this ARARs Table prior to the
finalization of this ROD.	
The ARARs Table was prepared as a revision to the ARARs Table
in a previously-approved ROD for Mather AFB. The proposed
additional ARARs have been considered through additional
discussions between the Air Force and the Regulatory Agency
representatives. As a result of these discussions, agreed-upon
changes have been incorporated in the ARARs Table as well as the
text of the ROD.
RWQCB-II.
Section 4
Many of the treated groundwater discharge locations are not
established at this time. As such the remedial actions are
incomplete. The ROD proposes conceptual discharge
locations. Therefore, treatment and discharge standards
cannot be fully established. As discharge locations are
established after this ROD has been finalized, ROD
amendments are require, or another regulatory mechanism to
assure the discharge of treated groundwater is adequately
regulated. For example, reference in the ROD to the
adoptions of future Waste Discharge Requirements and/or
NPDES permit that would be incorporated as part of the
ROD. This procedure would be quicker, more cost effective
and more flexible.
Additional text has been added to the ROD to address limitations of
the discharge of treated groundwater to the surface and to identify
the process for implementing specific surface discharge options.
RWQCB-IH.
Section 4
Specific objectives for the monitoring are required in the
ROD. Although we consider monitoring to be substantive,
detailed monitoring requirement in the ROD itself would be
cumbersome to change in the future. Attachment 2 is
suggested language	
Changes based on the suggested language have been incorporated in
the ROD..
                                                                   Page 5 of 20

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                                                        DRAFT RESPONSES TO COMMENTS ON
                                                            FINAL DRAFT CB-PART1 ROD
                                                                      11/15/96
 RWQCB-IV.
 Section 4
 Many chemicals were eliminated from the list of potential
 chemicals of concern. While this appears be appropriate for
 determining cleanup levels for the ground water, the presence
 of the chemicals should be considered in setting effluent
 limits for discharges, particularly for surface water
 discharges. Neither the substantive waste discharge
 requirements or the ARARs table contains effluent limits for
 constituents such as DBCP or EDB. The document should be
 clarified to state that discharge requirements will address all
 constituents that may effect receiving water or its beneficial
 use, not just constituents of concern	
 Additional language has been included in the ROD to address
 surface water discharge.
RWQCB-V.
Section 3
The ROD should evaluate all nine CERCLA criteria,
including the modifying criteria. It is not clear that the State
or public acceptance has been obtained. Public acceptance
was achieved during the Proposed Plan process and we are
working toward State acceptance. Please incorporate
modifying criteria in CERCLA criteria evaluation.	
Revisions have been incorporated in Section 3.8 to address State
and community acceptance.
RWQCB-S-1.
Section 2.4.1
Selected
Remedy: Main
Base Plume,
Phase 1
The fourth sentence should be removed, because this ROD
establishes cleanup levels, objectives and technologies not in
the OU-1 Interim ROD. This sentence infers that we are still
implementing the OU-1 ROD. Clearly this ROD is the Final
ROD for the OU-1 Interim ROD.
Reference is made here and elsewhere to the OU 1 and OU 2 areas
and systems, but the CB-Part 1 ROD does not imply that the earlier
RODs, under which these systems were implemented, remain in
effect. The CB-Part 1 ROD clearly states that these earlier
groundwater RODs are superseded and replaced by the CB-Part 1
ROD.
RWQCB-S-2.
Section 2.6 -
Signature for
Lead and
Support
Agencies
Section 2 should clarify that by signing the document, the
State is concurring with the remedy but is not making
statutory determinations under the Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA) and is not "approving" the remedy.	
The signature page is consistent with EPA guidance for ROD
preparation and is similar to that of previously-approved RODs. If
desired by the State, a footnote will be added stating that the State
signature indicates'concurrence with the selected remedy.
RWQCB-S-3.
Section 3.5.4 -
Confined HSZ
This Section states that BTEX constituents have been
reported, but none exceed MCLs or PRGs. Secondary MCLs
should be included and evaluated, which incorporates taste
and odor thresholds.
This section summarizes findings from the CB-Part 1 RI which did
not include taste and odor.

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                                                        DRAFT RESPONSJTO COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                        11/15/96
RWQCB-S-4.
 Section 3.6.3.1
 - Groundwater
 Plume and
 Contaminant
 Screening
 Process
This Section specifies that certain chemicals were eliminated
from the list of potential chemicals of concern. While this
may be appropriate for determining cleanup levels for the
groundwater, the presence of the chemicals should be
considered in setting effluent limits for discharges,
particularly for surface water discharges. Neither the
substantive waste discharge requirements or the ARARs table
contains effluent limits for DBCP or EDB. There are several
other sections where this issue is raised, for example in
section 3.5.3.2. The document should be clarified to state that
discharge requirements will address all constituents that may
effect receiving water and its beneficial uses, not just
constituents of concern.	
The ROD contains treatment requirements for constituents other
than COCs.  Revised language based on input from RWQCB has
been incorporated to clarify discharge requirements.
RWQCB-S-5.
Section 3.6.3.3
- East Base
Plume Region
It states in this Section that bromodichloromethane, DEHP,
carbon tetrachloride and PCE are excluded from
consideration because they "occur regionally in groundwater
either naturally or due to regional contamination." We do not
agree with this conclusion since it is not supported by data.
All these constituents exceed the carcinogenic risk or hazard
index level and should be included as a COC.
This section has been revised to clarify the basis for not including
bromodichloromethane, DEHP, carbon tetrachloride and PCE. For
bromodichloromethane and DEHP, the basis is step 3 of the FS
screening strategy (COPC does not form a plume as defined in the
RI). For carbon tetrachloride and PCE, the basis is the low
concentration, mass, plume size and isolated occurrence.
RWQCB-S-6.
Section 3.7.3,4
and 5
These sections describe the extraction alternatives and states,
"the groundwater remediation time may range from ten to 60
years, depending on the HSZ that is being remediated." The
remediation time is also dependent on how aggressively (fast)
the groundwater is extracted. The more aggressive (the higher
the pumping rate) the shorter time period for remediation.
This concept should be added to this sentence or paragraph.
Text revised as suggested.
RWQCB-S-7.
Section 3.7.3 -
Alternative 3
Extraction with
TCE Capture
Objectives of 5
ug/1    	
On page 43, last paragraph, twice "5 mg/1" is printed and it
should be 5 ug/1, please change.
Text revised as suggested.
                                                                     Page 7 of 20

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                                                         DRAFT RESPONSES TO COMMENTS ON
                                                              FINAL DRAFT CB-PART1 ROD
                                                                        11/15/96
 RWQCB-S-8.
 Section 3.8 •
 Detailed and
 Comparative
 Analyses of
 Remedial
 Alternatives
 The second paragraph, last sentence, it states, "The modifying
 criteria, (8) State/Support Agency acceptance and (9)
 Community Acceptance, will be evaluated during the public
 review and comment period." This statement should be
 updated since Community acceptance has already been done,
 and we are working toward State acceptance.
 Text revised as suggested.
 RWQCB-S-9.
 Section 3.8.2 -
 East Base
 Plume
 Please see comment 4 on the modifying criteria.
 Text revised as suggested.
 RWQCB-S-10.
 Section 3.8.2.2
 - Compliance
 with Applicable
 or Relevant and
 Appropriate
 Requirements
 In this Section, last paragraph, and the East Base Plume
 discussion on page 65 refer to the trigger for active
 remediation. The two discussions are inconsistent. Page 60
 states that it the trend to decrease does not continue or the
 concentrations increase active remediation would be
 implemented. Page 65 refers to an evaluation of whether the
 concentrations will not fall below the cleanup levels or if
 "significant" migration occurs then active remediation will be
 implemented. Page 65 should be changed to be consistent
 with Page 60. In addition, "significant" migration is vague
 and therefore, not useful. Migration above the cleanup levels
 should not be allowed at all.
Text revised as suggested. The word "significant" will be replaced
by "plume".
RWQCB-S-11.
Section 3.8.2.4
- Reduction of
Mobility,
Toxicity, or
Volume
The third paragraph of this section states, "...but would
reduce the potential for additional contamination to be
introduced." This sentence is unclear on where this
"additional contamination" is being introduced. This
alternative does not prevent additional contamination from
leaching from the vadose zone but, it may prevent significant
cross-contamination between the HSZs. This should be made
clear in the text
Text revised as suggested.
RWQCB-S-12.
Section 3.9.2.3
-Cost-
Effectiveness
This Section states that the State concurs that the selected
remedy fulfills the nine criteria. It is not within the
jurisdiction of the State to make any final determination about
compliance with CERCLA. The reference to the State should
be deleted.
The reference to concurrence on fulfilling nine criteria of the NCP
has been deleted.
                                                                      Page

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                                                        DRAFTRESPONSHFO COMMENTS ON
                                                            FINAL DRAFT CB-PART1 ROD
                                                                      11/15/96
RWQCB-S-13.
 Section 4.1.2-
 State Chemical-
 Specific
 ARARsand
 TBCs
 The second paragraph in Section 4.1.2 should be clarified by
 adding the following sentence:
 "However, the remedies selected are intended to control
 further migration and, therefore, comply with Resolution No.
 68-16 as interpreted by the SWRCB."	
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated.	
RWQCB-S-14.
 Section 4.2 -
 Location-
 Specific
 ARARsand
 TBCs
Last paragraph states, "no permanent surface water occurs on
Castle AFB." This infers that there is no proposed surface
water discharge and thereby, no locations specific ARARs for
surface water. This ROD proposes surface water discharge.
Two specific discharges are proposed currently, the discharge
via the West Base Drain (storm drain), to Canal Creek, and
alternative discharge to Casad Canal if the OU-2 reinfection
field is unable to handle the total flow from the treatment
system. Both discharges are to surface water and Location-
Specific ARARs apply. This section needs to be changed and
subsequently Sections 4.2.1 and 4.2.2	
The statement concerning the absence of permanent surface waters
on Castle AFB has been deleted.
RWQCB-S-15.
Section 4.3.2.2
State
Groundwater
ARARs
The third paragraph states that the Central Valley Region
Basin Plan, SWRCB Resolution 68-16, SWRCB Resolution
88-63 and SWRCB Resolution 92-49 are relevant and
appropriate. We believe that these ARARs are applicable.
This paragraph also is not consistent with Table 4-2 of this
document, which states th.at the Central Valley Region Basin
Plan, SWRCB Resolution 68-16, and SWRCB Resolution 88-
63 are applicable/ SWRCB Resolution 92-49 we believe is
applicable, not relevant and appropriate for groundwater
cleanup. This paragraph needs to be changed to state that
Central Valley Region Basin Plan, SWRCB Resolution 68-
16, SWRCB Resolution 88-63 and SWRCB Resolution 92-49
are applicable.	
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives.  As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated.
                                                                    Page 9 of 20

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                                                        DRAFT RESPONSES TO COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                       11/15/96
 RWQCB-S-16.
 Section 4.3.2.2
 - State
 Groundwater
 ARARs
 On Page 74 (he following sentence should be added to the
 end of the second full paragraph on this page:
 "However, the remedies selected are intended to control
 further migration and, therefore, comply with Resolution No.
 68-16 as interpreted by the SWRCB."

 In the fourth sentence of the third full paragraph, COC should
 be deleted and replaced with "constituents." Effluent limits
 should be specified for all constituents that might impact the
 receiving water or its beneficial uses, not just for COCs.
 Changes to the ARARs section (Section 4) have been considered
 through additional discussions between the Air Force and the
 Regulatory Agency representatives. As a result of these discussions,
 agreed-upon modifications to the ARARs Table and text have been
 incorporated.

 The recommended change to the fourth sentence of the third full
 paragraph has also been incorporated.  '

 See also response to comment RWQCB-S-4.	
 RWQCB-S-17.
 Section 4.3.2.2
 • State
 Groundwater
 ARARs
The fourth paragraph needs to be changed to state that
SWRCB Resolution 68-16 will be the basis for establishing
numerical limits for discharge to surface water. The
paragraph discusses only reinjection into groundwater.
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated.
RWQCB-S-18.
Section 4.3.2.2
-State
Groundwater
ARARs
On Page 75 and 76 the remedies selected in this ROD are for
groundwater not vadose zone so this discussion about the
interpretation of Resolution No. 92-49 as it applies to the
vadose zone seems out of place. It should be clarified in the
first full paragraph that the State believes that there are
sections of Resolution No. 92-49 that are substantive in
addition to Section ffl.G. The second full paragraph should
state that the State responded with a legal position that
Resolution No. 92-49 is an applicable State ARAR.	
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As  a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated.
RWQCB-S-19.
Section 4.3.2.2
-State
Groundwater
ARARs
On Page 76 the use of professionals licensed and/or certified
in California should be a substantive requirement.
Changes to the ARARs section (Section^) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As a result of these discussions,
agreed-upon modifications to the ARARs'Table and text have been
incorporated.	
RWQCB-S-20.
TAB 4-
Substantive
Requirements
There should be effluent limits for pesticides, such as DBCP,
EDB and DEHP. They are found in the groundwater and
should not be removed and transported to areas with lower
concentrations or no detectable levels. This will comply with
SWRCB Resolution 68-16.
The Substantive Requirements document has been removed and
replaced by revised text in the ROD.
                                                                    Page Jtef 20

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DRAFT RESPONSWW COMMENTS ON
   FINAL DRAFT CB-PART1 ROD
            11/15/96
RWQCB-S-21.
RWQCB-S-
ATTCH2
Table 4-3 -
Groundwater
Discharge
Treatment
Standards
Section 2.8.3. 3a
Monitoring
Table 4-3 is specific to groundwater reinjection not to surface
water discharge. Surface water discharged is planned as one
of the alternatives and needs to be included. Also, this table
does not include the different chemical characteristics of the
HSZs. For example DBCP, EDB, nitrates and some metals
are found at higher concentrations in the Shallow HSZ than in
Confined HSZ, a major drinking water aquifer. Reinjection of
water containing nitrates, DBCP etc. into Confined HSZ
would affect the high quality of the Confined HSZ and is
therefore, not acceptable. We concur with the concentrations
in the tables but, the table does not cover the complete
spectrum of chemical constituents found in the groundwater.
This is required for establishing receiving water and effluent
discharge limits and may be impossible to do at this time
without knowing the specific discharge.
Suggests incorporation of monitoring requirements summary
Table 4-3 indicates its applicability to surface discharge as well as
reinjection. The title of the table has been modified to refer to
'Treated Groundwater Discharge Standards'
Discharge limitations have been addressed in revised text added to
the ROD based on input from RWQCB.
Suggested changes based on input from RWQCB have been
incorporated to address monitoring.
         Page 11 of 20

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                                                          DRAFT RESPONSES TO COMMENTS ON
                                                              FINAL DRAFT CB-PART1 ROD
                                                                         11/15/96
 EPA-G-1.
                  I understand the approach being advocated by the Water
                  Board, which is to leave the options open for discharging the
                  treated effluent, to allow the Air Force the opportunity to
                  conduct a water reuse study. Nevertheless, the discussion in the
                  ROD regarding the discharge of the treated effluent is too
                  sparse. The ROD has to include more discussion regarding the
                  various discharge  options and the rationale for leaving these
                  options open, and  the process.for informing the public and
                  identifying the ARARs once the Air Force determines which
                  discharge option will be used.	
                                                           New text has been added to further define the discharge options for
                                                           treated water. In particular, this new text identifies the bounds for
                                                           surface discharge (i.e., discharge rate and locations) that are
                                                           included within the selected remedy. The ARARs table has been
                                                           expanded to include additional ARARs associated with surface
                                                           discharge within the selected remedy.
EPA-S1-1.     p.5
                 Phase I, sixth line, refers to treated water release levels
                 stipulated in this ROD. What are these and where are they set
                 out? Are these the same as the effluent release levels in Table
                 4-3, Section 4? Aside from EPA's problem with this table, i.e.,
                 it looks like a Permit, don't these discharge levels only apply to
                 surface discharge? Perhaps we should leave these release
                 levels out until the Air Forte decides it will discharge the
                 treated effluent to land or surface water.
                                                          Clarification has been added to indicate that the effluent release
                                                          levels are found in Table 4-3, Section 4. Note that the release levels
                                                          apply to both reinjection as well as surface discharge, both of which
                                                          are included in the selected remedy.
EPA-S1-2.
p.7
The signature, line for EPA should be changed to Dan Opalski,
Branch Chief.
The signature line has been changed as requested.
EPA-S1-3.
p.13
There are several typo/grammatical errors on this page. First
paragraph, second to the last sentence, delete "been,"; third
paragraph, second to the last sentence is not a complete
sentence.
Corrections have been made.
EPA-S1-4.
p.15
Second full paragraph, last sentence refers to a dispute
resolution for OU1 which established the quantitative
requirements for treatment of groundwater for the OU. We
should just state briefly what those requirements are.
Text has been modified as suggested.
EPA-S1-5.
p. 18,
Section 35, third paragraph states the volume and mass of
TCE in the Main Base Plumes and the East Base Plume
Region. What about in the Castle Vista Plume?	
Values for the Castle Vista plume have been added
                                                                      Page ]^ 20

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DRAFTRESPO^frO COMMENTS ON
   FINAL DRAFT CB-PART1 ROD
            11/15/96
EPA-S1-6.
EPA-S1-7.
EPA-S1-8.
EPA-S1-9.
EPA-S1-10.
EPA-S1-11.
EPA-S1-12.
EPA-S1-13.
EPA-S1-14.
p. 19
p.20
p.21
p.22
p.28
p.29
p.30
p.30
p.37
First full paragraph mentions a pump and treat prescriptive
remedy for the Castle Vista Plume. What are the cleanup levels
for this plume?
Section 3.5.4 does not state what the TCE levels are in the
confined HSZ.
First paragraph states that the risk estimates do not reflect
reductions in contamination arising from ongoing cleanup
efforts where groundwater remediation is currently in progress.
Do we mean here that the risk estimates are conservative
because it does not take into account the fact that there are
ongoing cleanup efforts?
Section 3.6.1.2, second paragraph. last sentence - it is unclear
as to which of the land uses identified earlier was used for the
risk assessment.
Landfill 4 Plume Region states that the total HI is 9.34. Yet,
this is a no-action site. Please explain why. Conversely, in the
East Base Plume Region (on the same page), the risk is within
the acceptable range and HI is below 1. Yet, remedial action is
being taken at this site. Explain why.
Again, in Landfill 1 Plumfc Region, the total HI is over 1, yet
this is a no-action site. On the same page, the risk range is
acceptable for Castle Vista Plume Region, yet a remedial
action (presumptive pump and treat) is begin taken at this site.
Second paragraph last sentence states that Castle Vista requires
additional characterization to determine whether remedial
action is warranted. Elsewhere in the ROD, it states that a
presumptive pump and treat remedial action will be taken at
this site.
Second to the last paragraph, last sentence states that there are
additional areas of groundwater remediation that are currently
not being addressed. What are these?
First paragraph, last sentence refers to current monitoring
information which indicates the need for active remediation at
the Castle Vista Plume. What is this information?
The overall cleanup objective for CB-Part 1 is stated elsewhere as
MCL for the plume contaminants. "Prescriptive remedy" has been
changed to "Presumptive remedy".
TCE concentration in the confined HSZ have been added.
Yes. The risk values are conservative for this reason.
The risk assessment values summarized in Table 3-4 are the most
conservative of the calculated risk values.
This section summarizes the results of the risk assessments. The
disposition of each plume is discussed in section 3.6.3.
This section summarizes the results of the risk assessments. The
disposition of each plume is discussed in section 3.6.3.
This statement refers to the findings of the RI/FS.
i
This statement will be clarified to indicate that it is the purpose of
CB-Part 1 to address the remaining areas of groundwater
remediation.
Additional text has been included to describe the new information
and the rationale for the remedial action at Castle Vista plume.
          Page 13 of 20

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DRAFT RESPONSES TO COMMENTS ON
   FINAL DRAFT CB-PART1 ROD
            11/15/96
EPA-S1-1S.
EPA-SI-16.
EPA-S1-17.
EPA-S1-18.
EPA-S1-19.
EPA-S1-20.
EPA-S1-21.
EPA-S1-22.
EPA-S1-23.
p.38
p.38
p.42
p.44
p.49
p.54
p.55
p.56
p.60
First paragraph partly addresses my concern regarding the
limited information in the ROD regarding the reasons for
leaving the discharge options open. [Please see general
comment above.] Why don't we state in this section that the
Air Force is conducting a reuse study?
This section only addresses the alternatives for the Main Base
Plume and the East Base Plume. What about the Castle Vista
Plume?
There is a statement that "(bjbecause no action would be taken
to contain the contaminant plumes, this alternative may not
meet the PRAOs." What is this referring to? Is it referring to
the selected remedy for this plume, which is well destruction?
East Base Plume - it states that only disposal by injection was
considered for this plume. Does this mean that the other
discharge options discussed elsewhere are only being
contemplated for the Main Base Plume Region. This should be
made clear.
How long will this alternative take?
Compliance with ARARs - second paragraph states that the 5.0
ug/1 TCE capture alternative complies with 92-49. What about
plume control? Delete reference to location-specific ARARs
here and in the next paragraph as I don't believe there are any
location-specific ARARs here.
Reduction of Mobility - second paragraph is difficult to
understand. Third paragraph, second sentence refers to "this"
alternative. Which one?
Implementability - bullet for Plume Control Alternative refers
to options 6A, 6B, 6C, and 6D. Which are these? Perhaps,
there should be some narrative description of these
alternatives.
Last paragraph - see comment 21 above.
This has been updated to refer to the water reuse study.
This section summarizes the Feasibility Study findings which were
limited to these two plumes.
Yes.
This section summarizes the results of the Feasibility Study with
respect to the alternatives considered. The selected remedy is
detailed elsewhere.
The projected time for active remediation (IS years) is provided in
paragraph 4; the last paragraph of this section also notes that there
is a possibility that the operation may extend beyond this period.
Reference is made to the 5 ug/1 capture alternative as the selected
alternative, and does not provide discussion of the other, non-
selected alternatives, including the plume control alternative.
Reference to location-specific ARARs has been deleted in both
paragraphs and in the referenced tables.
The second paragraph has been re-worded to improve readability.
The first sentence of the third paragraph identifies the "Plume
Control alternative".
The Description of Alternatives, including sub-alternatives, is
presented in Section 3.7.
This paragraph has been re-worded to improve readability.
          Page 14-of20

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DRAFT RESPO^frO COMMENTS ON
   FINAL DRAFT CB-PARTI ROD
            11/15/96
EPA-S1-24.
EPA-S1-25.
EPA-S1-26.
EPA-S1-27.
EPA-S1-28.
EPA-S1-29.
EPA-S1-30.
EPA-Sl-31.
p.64
p.65
p.65
p.66
p.66
p.72
p.74
p.74
Phase 3, third paragraph, refers to release levels for treated
groundwater. Aren't these levels only for land/surface
discharge?
East Base Plume - states that within one year of the ROD, the
AF will provide a reassessment of the need for remediation. Is
this because we expect to have monitoring data then? The
sentence following this states that reassessment will continue
annually until active remediation is initiated or the level of
contamination falls below cleanup levels for a period of at
least one year. How long does the AF need to maintain this
level (below cleanup levels) before the AF will not be required
to conduct any more reassessment?
Castle Vista Plume - again, refers to "data" without specifying
what this data shows.
Second line from the top of the page refers to corrective action
monitoring under Chapter 15. Why are we not using the
monitoring in Title 22, instead of Title 23? In the same
paragraph, last sentence, states that "if at any time" monitoring
or modeling indicates that contaminants will not meet mcls
within a reasonable time...." Is this after the one year (see
comment 25 above)?
Attainment of ARARs - states that action-specific ARARs will
be met for the reinjection of groundwater. What about the
ARARs for the other disposal options?
First bullet, surface water, should be deleted here and moved
to the action-specific ARARs. Likewise, in the paragraph
following theie bullets, delete first sentence which refers to
surface water.
First full paragraph refers to the CVR Basin Plan. Please add
the following phrase: "which establishes numerical and
narrative water quality objectives to ensure the reasonable
protection of beneficial uses of water."
Last paragraph - identifies the ARARs for reinjection into
clean areas and the plume. Should we leave these out for the
future ROD amendment/ESD when the Air Force determines it
will reinject?
No; the levels in Table 4-3 include both reinjection and surface
discharge.
No; this refers to the Air Force's commitment to reassess on an
annual basis, with the first assessment being that of the ROD. The
text states that the Air Force would continue the annual reassessment
until either active remediation begins, or the levels fall below the
cleanup levels and remain there for a period of one year. If the
second condition is met, there would be no requirement to continue
annual reassessments.
Additional text has been included to describe the findings at Castle
Vista plume and the rationale for the remedial action.
The issue of the basis for monitoring is under review and
appropriate text changes will be implemented.
With regard to the second point, this is not necessarily "after the
first year," but in effect will likely be coordinated as part of the
LTGSP annual revaluation.
Modify text to include ARAR compliance for all water disposal
options.
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated '
Text has been changed as suggested.
No. Reinjection is included as pan of the selected remedy.
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                                                         DRAFT RESPONSES TO COMMENTS ON
                                                             FINAL DRAFT CB-PARTI ROD
                                                                        11/15/96
 EPA-S1-32.
 p.75
 First paragraph, beginning with the sentence "[f]or any
 alternative cleanup levels less stringent than background,..."
 until the end of the paragraph. This language identifies Chapter
 15 as the ARAR. This language should be deleted (or
 rewritten) to make it clear that 92-49 is the ARAR here which
 directs establishment of cleanup levels that are above
 background levels based on the factors enumerated in
 2550.4(el	
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives. As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated.
EPA-S1-33.
p.75
Last full paragraph on this page through the first paragraph on
the next page should be deleted. These paragraphs address
vadose zone remediation which is not relevant to this ROD.
Changes to the ARARs section (Section 4) have been considered
through additional discussions between the Air Force and the
Regulatory Agency representatives.  As a result of these discussions,
agreed-upon modifications to the ARARs Table and text have been
incorporated	
EPA-S1-34.
Table 3-17
Compliance with ARARs: alternative 6 - states "probably" not
comply with state groundwater protection ARARs. Why not
just state it will not comply?	
This table is a summary of the RJ/FS evaluation that says "probably"
won't comply.
EPA-S1-35.
Table 4-1
Chemical-Specific ARARs for Drinking and Groundwater: Are
these the cleanup levels for the groundwater or the treatment
levels for the water that will be discharged? Since this ROD
will not specify what discharge option the AF will take, we
should just have aquifer cleanup levels.
These are drinking water standards, regardless of discharge source.
Note that the selected remedy does not state that the discharge
option will be selected later, only that the most appropriate design
mix of reinfection, surface discharge and reuse will be determined in
RD/RA.  The remedy will include both reinjection and surface
discharge, but in an as-yet undetermined mix.
                                                                     Page
                                                                20

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                                                        DRAFT RESPONSETfO COMMENTS ON
                                                             FINAL DRAFT CB-PART1 ROD
                                                                       11/15/96
EPA-S1-36.
Table 4-2
 Action-Specific ARARs:
 p.4: second row. NPDES - only an ARAR if there will be a
 surface water discharge. If we are going to keep this in, please
 delete second sentence in first paragraph. Change second
 paragraph (single sentence) to read: "These sections of the
 regulation governing impacts to water quality apply to the
 discharge of treated water to surface water." p.4: third row,
 Order 92-0$ - clarify that the substantive requirements of this
 general stormwater permit apply to the remedial activities at
 Castle AFB. It may help if the fourth paragraph is moved to
 the beginning of the description column, making it the first
 paragraph.

 p.5: first row. Water Quality Objectives - unless SMCls have
 been promulgated by the State, these are not ARARs, just
 TBCs. Last sentence which reads "California standards which
 may be ARARs for the site include 22 CCR 6444 Tables A
 and B and 22 CCR 64449 Tables A and B." should be deleted.
 First,  what are these standards? Second, if these standards are
 ARARs, they should be set out.

 p.5: second row, Wastewater reuse policy - rewrite first
 sentence to read: "Requires evaluation of land disposal as an
 alternative to discharge to surface waters.'

 p.6: first row - second paragraph seems redundant and should
 be deleted. If we keep this paragraph, delete last sentence, or
 specify what these requirements are and state whether they are
ARARs, instead of the present statement which is that they
 "may  be ARARs for the site."

p.6: second row - second paragraph should be deleted. Last
paragraph should be rewritten to read: "Subject to the
 limitations described above, this requirement is relevant and
appropriate for establishing cleanup levels of groundwater
affected by releases of contaminants.."	
Table 4-2 has been revised based on discussions between legal staff
of USAF. US/EPA and Cal/EPA.
                                                                    Page 17 of 20

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DRAFT RESPONSES TO COMMENTS ON
   FINAL DRAFT CB-PART1 ROD
            11/15/96
EPA-S1-37.
EPA-S1-38.
EPA-S1-39.
EPA-S1-40.
EPA-S1-41.
EPA-S1-42.

EPA-S1-43.
EPA-S1-44.
Table 4-3
RE: DTSCs
Comments:
RE: Regional
Board's
Comments:






Groundwater Discharge Treatment Standards:
Again, since we don't specify what is the chosen discharge
option, we should take this table out. If we decide to keep this
table, I have the following questions:
1) why are we using CA EPA cancer potency factors for the
daily maximum standard for injection into the clean portion of
the aquifer. Are these standards promulgated, and are they
more stringent than Federal standards?
2) Am I correct in assuming that when we use (he CA MCL for
the standard for injection into the contaminated portion of the
aquifer, this standard is more stringent than the Federal MCL?
p.4, #11: shouldn't the criteria for reassessing the need for
active remediation be in the ROD?
p.l, Major Comment # II: Are there detailed monitoring
requirements in the ROD?
What is attachment 2?
p.2. Major Comment #V: I'm not sure I understand the reason
for the distinction being made here regarding State
"acceptance" versus "concurrence." Regardless, of the
language chosen, it should be clear in the ROD that the State
agrees with the remedy.
p.2, #3: secondary mcls for taste and odor thresholds should be
TBCs.
p.4, #15: only those portions of the Basin Plan which establish
water quality objectives, including numerical and narrative
standards that protect the beneficial use of surface and
groundwater are potential ARARs.
p.4, #17: Res. 68-16 is the basis for setting the limits for
reinjection while the Basin Plan is the basis for establishing the
limits for discharge to surface water.
p.4,#19: The use of professionals licensed in CA is not a
substantive requirement.
1) The use of Cal/EPA potency factors was based on the approach
taken in the previously-approved ROD at Mather AFB.
2) Yes
See response to comment DTSC-S-1 1.
The text of the ROD has been revised to include monitoring
requirements. Attachment 2 to the RWQCB comments was an
initial draft of their suggested language.
Concur.
Changes have been made to the ARARs section of the ROD to
address SMCLs.
Changes have been 'made to the ARARs section of the ROD in
consultation with the agencies.
Changes have been made to the ARARs section of the ROD in
consultation with the agencies.
Concur. The text for the ARARs section has been revised based on
discussions between agency and Air Force representatives.
         Page

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DRAFT RESPONS^tO COMMENTS ON
   FINAL DRAFT CB-PARTI ROD
            11/15/96

EPA Specific CoirimentS(2ha;scty|g^g^^ ^*. > v. :V' £•.*.-., .$fcv, '& • ^ :.** ^T&s-»$$^
EPA-S2-I.
EPA-S2-2.
EPA-S2-3.
EPA-S2-4.
EPA-S2-5.
EPA-S2-6.
EPA-S2-7.
EPA-S2-8.
Page 5, Phase 1
Page 6, Section
2.4.2
Page 6, Section
2.4.3
Page?
Page 13, Last
Paragraph
Page 17, Last
Paragraph
Page 18,
Section 3.5,
First Paragraph
Page 19,
Second
Paragraph, Last
Sentence
The text in this section should be edited to reflect that the Main
Base Plume work described here has been completed.
The statement, "If further active remediation is needed, 	 ",
should be modified to indicate simply that appropriate
remedial action will be selected based on the conditions that
trigger the need for remediation and existing technology at the
time.
The second sentence needs to be rewritten so it makes sense.
The third sentence will need to be revised since the decision
has been made to treat the Castle Vista plume contamination.
The signature name for Chief, Federal Facilities Branch should
be changed to Dan Opalski.
The Installation Restoration Program (IRP) phases I, II, and III
described here may be confused with the three phases of
groundwater cleanup identified for the Main Base Plume that
are introduced in Section 2.0 (Declaration For The Record Of
Decision). It may be helpful to include a parenthetical
comment "(not to be confused with the three phases of the
Main Base plume RD/RA )" or to rewrite the text to better
differentiate between the IRP phases and the CB Part 1
remedial design and remedial action (RD/RA) phases.
Figure 3-5 does not show the Castle Vista Plume. Figure 3-5
should be modified to show the location of the Castle Vista
Plume.
Since the ROD identifies the need to clean up the Castle Vista
Plume, cis- 1,2-dichloroethene (cis-l,2-DCE) also should be
identified as a Chemical of Concern in this section.
"Prescriptive" remedy should be replaced with "presumptive"
remedy. It should be noted that an addendum should be
prepared for the CB Part 1 Remedial Investigation/Feasibility
Study (RI/FS) Report to describe the additional data obtained
on Castle Vista Plume and why the decision was made to
remediate this plume.
Text clarification has been incorporated.
Text clarification has been incorporated as suggested.
Revisions have been made as suggested.
Revision have been made as suggested.
Text clarification has been incorporated as suggested.
Figure 3-5 has been modified to show the location of Castle Vista
plume.
i
Text has been changed as suggested.
i
The term "prescriptive" has been corrected. No addendum is
planned for the RI/FS; however, new text has been added to the
ROD to describe the additional data and rationale for remediation of
Castle Vista plume.
         Page 19 of 20

-------
                                                          DRAFT RESPONSES TO COMMENTS ON
                                                              FINAL DRAFT CB-PARTI ROD
                                                                         11/15/96
 EPA-S2-9.
 Page 31.
 Second
 Paragraph,
 Second
 Sentence
 This sentence should be changed to reflect (hat institutional
 controls prohibiting pumping from contaminated groundwater
 should preclude exposure of surface receptors to the
 contaminated water.
 Text clarification added as suggested.
 EPA-S2-IO.
 Page 37. First
 Paragraph, Last
 Sentence
 There needs to be a fuller explanation of why remedial action
 is justified for the Castle Vista plume.
See response to comment EPA-S2-8
 EPA-S2-11.
 Page 42. Third
 paragraph
This paragraph is very unclear. It implies is that well
destruction and monitoring is more implementable for the east
base plume than well head treatment is for the main base
plume. This statement should be clarified.	
The interpretation of the text is correct; nevertheless, the text has
been rewritten for better clarity.
EPA-S2-12.
 Page 42. Main
 Base Plume
The first sentence of the second paragraph is redundant with
the beginning of the first paragraph and should be removed.
The second sentence of the first paragraph does not make
sense. The other existing extraction process options other than
extraction wells should be clarified. This sentence should be
rewritten or deleted.
Text changes made as suggested.
EPA-S2-13.
Page 43, Last
Paragraph, Last
Sentence
It is unclear what is meant by administrative feasibility, and
how administrative feasibility influences the remedy selection.
Reference to administrative feasibility has been removed from this
discussion.
EPA-S2-14.
Page 44, Third
Paragraph,
Second
Sentence
It is unclear whether the same treatment options evaluated for
the Main Base plume were considered for the East Base plume,
and whether reinjection was considered as the only option for
disposal. It is believed that canal discharge or possible reuse
also were considered as disposal options for the East Base, but
were judged to be too costly or impractical. This section
should be rewritten to make it more clear and accurate.
Sentence revised for clarity.
EPA-S2-15.
Page 44, Last
Paragraph, Last
Sentence; Page
45, First
Sentence
It is unclear why the lower subshallow (LSS)
hydrostratigraphic zone (HSZ) is mentioned in conjunction
with the East Base plume since there is not any contaminatiori
in the LSS HSZ. The correct remediation time for the East
Base plume is that time estimated for the shallow HSZ.	
Text has been revised as suggested.
                                                                      Page 20 of 20

-------
LISTING OF ADMINISTRATIVE RECORDS




              FOR




      CASTLE AIR FORCE BASE

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or            FILE
DATS        SUBJECT OR TITLE                         CORP.  AUTHOR         NUMBER
04 Jan 84   HQ SAC Letter to USAF OEHL Regarding     Burnett,  Ronald D,     10
            Final Phase I Report Completion,  Oct     Col
            83,  and Request for Phase II to Begin    HQ SAC/SGPB
            ASAP
04 Jan 84   CDHS Letter to HQ SAC Regarding Phase I  Sandhu,  Mohinder S     11
            Completion and Phase II Progression      California
                                                     Department of Health
                                                     Services
16 Jan 84   Base Letter to HQ SAC Regarding          Astorino,  Loring R,    13
            Community Understanding and Support for  Col
            Phase.II IRP                             93  BMW/CC
02 Feb 84   Base Letter to HQ SAC Regarding Jan 84    Hedrick,  Stephen P,    14
            TCE Sample Results Collected from Wells  Capt
            1-4 and Four Distribution Points    .     93  MG/SGPB
03 Feb 84   Base Letter to CRWQCB Regarding          Dempsey,  Robert E,     15
            Estimated Timetable for Phase II         Col
                                                     93  BMW/CV


28 Feb 84   Phase II Presurvey Meeting Minutes       Hedrick,  Stephen P.    18
                                                     Capt
                                                     93  MG/SGPB


Mar 84      Phase II, Problem Confirmation and       Roy P Weston, Inc.     17
            Quantification Presurvey Report, Vol I,
            Technical Work Plan
05 Mar 84   Water Analysis Results, 02 Feb 84:        Hedrick, Stephen P,     19
            Wells 1-9 and 11, Test Wells 12-18,  and  Capt
            Four Distribution Points                 93 MG/SGPB


05 Mar 84   Internal Base Letter Regarding Phase II  Hedrick, Stephen P,     32
            Presurvey RPM Meeting Minutes, 28 Feb    Capt
            84                                       93 MG/SGPB

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
26 Mar 84   TCE Sample Results, Between 24 Oct 83    Hedrick, Stephen P,     20
            and 06 Mar 84                            Capt
                                                     93 MG/SGPB
26 Mar 84   TCE Sample Results, Mar 84
                                         Hedrick, Stephen P,    21
                                         Capt
                                         93 MG/SGPB
01 May 84   TCE Sample Results, Apr 84
                                         Hedrick, Stephen P,  1018
                                         Capt
                                         93 MG/SGPB
04 Jun 84   TCE Sample Results, May 84
                                         Hedrick, Stephen P,
                                         Capt
                                         93 MG/SGPB
  22
18 Jun 84   HQ SAC Letter to HQ AFESC/DEV
            Transmitting Phase II Stage 1, Task
            Description and Presurvey Report
                                         Hauver, Robert C,
                                         Col
                                         HQ SAC/SGPB
  25
27 Jun 84   TCE Sample Results, Jun 84
                                         Hedrick, Stephen P,     23
                                         Capt
                                         93 MG/SGPB
24 Jul 84   CDHS Letter to HQ SAC Regarding Review   Norman, William F
            of Phase II Stage 1                   -   Merced County
                                                     Department of Health
                                                                 26
28 Aug 84   HQ SAC Letter to USAF OEHL Regarding
            Comments on Phase II Stage 1 Task
            Description
                                         Burnett, Ronald D,
                                         Col
                                         HQ SAC/SGPB
  27
20 Mar 85   Tox Summary Report
                                         Hansen, Earl M, PhD
                                         Weston Analytical
                                         Laboratories
  34

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
19 Apr 85   TOC and Phenols Results - Water Samples  Hanseri, Earl M, PhD     35
                                                     Weston Analytical
                                                     Laboratories
Nov 85      Phase II Stage 1,
            Confirmation/Quantification Technical
            Report,  Vol I of II
                                         Roy F Weston, Inc.
  38
Nov 85      Phase II Stage 1,                        Roy F Weston, Inc.
            Confirmation/Quantification Appendices,
            Vol II of II
                                                                 39
17 Dec 85   MCDH Letter to HQ SAC Regarding Review   Norman, William F
            of Phase II Stage 1                      Merced County
                                                     Department of Health
                                                                 43
22 Jan 86   Base Message to HQ SAC Requesting
            Initiation of Phase IVA Action
            Coordination Meeting
                                         Buzak, Jan
                                         Kaiser, Donald w,
                                         LtCol
                                         93 CSG/DE
  44
24 Jan 86   HQ SAC Memorandum Regarding Meeting, 29  Brown, Doug, Maj
            Jan 86                           *"       HQ SAC/DEPV
                                                                 45
31 Jan 86   Newspaper Article, "CAFB Will Fund New   De La Cruz, Mike
            Water Well"                           .  The Merced Sun Star
                                                                 33
05 Feb 86   Meeting Minutes of Phase IV
            Coordination Meeting, 29 Jan 86
                                         Kaiser, Donald H,
                                         LtCol
                                         93 CSG/DE
23 Apr 86   EPA Comments on Phase IVA RAP Task       EPA Region IX
            Report No 1, Site Characterization Plan
            for Main Base, South and West
            Flightline Sectors
                                                                 46

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
Jun 86
Phase -IVA, Statement of Work RAP
Hazardous Materials     51
Technical Center
30 Jul 86   EPA Comments on Phase IVA RAP SOW
                                         EPA Region IX
                       53
30 Jul 86   EPA Letter to Base Regarding Comments    Seraydarian, Harry
            on Draft Memorandum of Understanding of  EPA Region IX
            Agreement for City of Atwater Potable
            Water Well, 20 Jun 86
                                                               911
Aug 86      EPA Letter to Base Regarding EPA Final
            Comments on Phase II Stage 1
            Confirmation/Quantification Technical
            Report and Phase IVA RAP SOW
                                         Takata,  Keith
                                         EPA Region IX
                        55
21 Aug 86   Summary of Meeting Regarding Domestic
            Well and Bellevue Road Water Main
            Project
                                         Reitz, Mark
                                         Boyle Engineering
                                         Corp.
                        56
11 Sep 86   Internal Base Letter Transmitting
            Copies of Phase IVA Kickoff Meeting
            Minutes, 29-30 Jul 86
                                         Kaiser,  Donald W,
                                         LtCol
                                         93 CSG/DEEV
                        57
18 Sep 86   Agreement for Installation of TCE
            Filtration System at Homeowners
            Residence
                                         Kirbie,  Darrel G,
                                         LtCol
                                         93 CSG/DEV
                        59
18 Sep 86   Phase IVA, RAP, Draft Task Report No 7
            CRP
                                         Oak Ridge National
                                         Laboratory
                        60
30
September
1986
PCB Spill Site -PCB Storage Facility
Building 1203
Volz, David E.        1049
Air Force HQ Combat
Support Group

-------
                            Castle AFB - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
15 October  PCB Clean-up Level for Spill Site
1986        Located Next to PCB Storage Facility,
            Building 1203
                                         Landis, Anthony J.
                                         P.E.
                                         Chief Site
                                         Mitigation Unit
                     1048
13 Nov 86   MCDH Letter to Base Petroleum            Palsgaard, Jeff H
            Contaminated Soils at East Perimeter     Merced County
            Road                                     Department of Health
                                                                65
18 Dec 86   Base Conversation with USACE Regarding   Randall, Steven G      68
            Procedures to Obtain Permit to Install   93 CSG/DEEV
            Monitoring Wells in MID Property


23 Dec 86   Base Letter to MID Requesting Permit to  Kaiser, Donald W,      70
            Construct and Maintain Pollution         LtCol
            Monitoring on MID Rights of Way          93 CSG/DE
87
Base Letter to Atwater Signal in
Response to Concerns of Resident
Wilson, James F, Col  164
93 CSG/CC
22 Jan 87   Phase IVA Meeting Minutes, 22 Jan 87     93 CSG/DEEV
                                                                87
28 Jan 87   ORNL Letter to HQ SAC Submitting         Loyd, John R
            Alternatives for Removal of TCE from •   Oak Ridge National
            Groundwater                              Laboratory
                                                                88
11 Mar 87   City of Atwater Letter to Base
            Regarding Status of Groundwater
            Investigation
                                         Haug, John A
                                         City of Atwater
                      899
09 Apr 87   CDHS Memo Regarding Preliminary Review   Buell, Reid
            of Phase IVA, RAP, Task Report No 1,     California
            Site Characterization for Main Base and  Department of Health
            South and West Sectors                   Services
                                                                71

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or             FILE
DATE        SUBJECT OR TITLE                         CORP. AUTHOR          NUMBER
24 Apr 87   EPA Letter to Base Transmitting          Takata, Keith           74
            Comments on Phase IVA Site               EPA Region IX
            Characterization Plan


22 May 87   CDHS Letter to Base Submitting Memos     Wang, David             84
            Summarizing Meeting/Conference Calls     California
            Addressing Phase IVA Work Plan           Department of Health
                                                     Services
Aug 87      Phase IVA, Site Characterization Plan    IT Corp.                96
06 Aug 87   Base Letter to EPA Transmitting Replies  Hodges, Harold W,       97
            to Comments on Phase IVA Work Plan       LtCol
                                                     93 BMW/CVE
16 Oct 87   EPA Letter to Base Regarding Comments    Martyn Goforth,        102
            on Sample Plan for Site                  Kathleen A
            Characterization Activities, Appendix D  EPA Region IX
            of Revised Phase IVA Site
            Characterization Plan
19 Oct 87   RI/FS and RD, Statement of Work          Martin Marietta        103
                                              *•      Energy Systems, Inc.


05 Nov 87   Newspaper Article, "Haug Clarifies CAFB  UNK                    90S
            Well Delay"


09 Nov 87   Base Letter to Resident Regarding        Chan, Arthur D         106
            Whether or not TCE is Absorbed into      93 BMW/CVE
            Skin and Inhaled While Bathing


09 Nov 87   CDHS Letter to Base Transmitting Review  Wang, David  .          107
            of Phase IVA Site Characterization Work  California
            Plan                                     Department of Health
                                                     Services

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP.  AUTHOR
FILE
NUMBER
13 Nov 87   EPA Letter to Base Transmitting
            Comments on Phase IVA Site
            Characterization Plan
                                         Zitnpfer,  Amy K
                                         EPA Region IX
 108
16 Nov 87   DOI Letter to Base Transmitting Plots
            of TCE Concentrations Sampled in Base
            Test Wells 13-18
                                         Avon,  Li zanne
                                         US Department of the
                                         Interior - Water
                                         Resources Division
 113
23 Nov 87   CDHS Letter to Base Transmitting Health
            and Safety Plan for Phase  IVA Site
            Characterization  Plan, Appendix B, Aug
            87
                                         Wang,  David
                                         California
                                         Department of Health
                                         Services
 112
08 Dec 87.  Base Letter Transmitting Agenda and
            Summary Regarding Meeting with
            Regulatory Agencies on Phase IVA Site
            Characterization Plan
                                         Chan,  Arthur D
                                         93 BMW/CVE
 111
15 Dec 87   Rl, SOW  for  Proposed JP-4 Fuel
            Distribution System and Update of Phase
            IVA Site Characterization Plan
                                         Martin Marietta
                                         Energy Systems, Inc.
 110
30 Dec 87   Base Letter  to  EPA Transmitting Minutes
            of  Phase  IVA Work  Plan Discussion
            Meeting,  17  Dec 87
                                         Chan,  Arthur D
                                         93 BMW/CVE
 114
08 Jan 88   EPA Letter to  Base  Regarding Receipt of
            Phase  IVA Site Characterization Plan
            Aug 87 and Sending  of  Comments 16 Oct
            87 and 13 Nov  87
                                         Anderson,  Julie
                                         EPA Region IX
 125
21 Jan 88   CDHS Thank You Letter to Base  for
            Responding to Comments on Phase IVA
            Work Plan,  SP,  and QAPP on TCE Plume
            Characterization Containing Concerns
            and Outstanding Issues
                                         Wang,  David
                                         California
                                         Department of Health
                                         Services
 124

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
03 Feb 88   EPA Letter to Base Regarding Receipt of  Anderson, Julie
            21 Jan 88 Letter Regarding Phase ZVA     EPA Region IX
            Work Plan
                                                                122
04 Feb 88   CDHS Letter to Atwater City
            Administrator Concerning Proposed
            Placement of Production Well Near
            Bellevue Elementary
                                         Wang,  David
                                         California
                                         Department of Health
                                         Services
                       910
07 Mar 88   EPA Letter to City of Atwater Regarding  'Anderson, Julie        904
            Oversight of Superfund RI Activities     EPA Region IX
28 Mar 88   Base Letter to EPA Regarding Response    Chan, Arthur D
            to Letters                               93 BMW/CVE
                                                                116
Apr 88
RI/FS, Work Plan, Vol I of IV
IT Corp.
 126
Apr 88      RI/FS, Sampling and Analysis Plan,  Vol   IT Corp.
            II of  IV
                                                                127
Apr 88      RI/FS, Health  and Safety Plan, Vol IV    IT Corp.
            of IV
                                                                129
May 88      Groundwater  Investigation, Northeast     Boyle Engineering      135
            Quadrant, Technical Report, Vol I of II  Corp.


May 88      Groundwater  Investigation, Northeast     Boyle Engineering      136
            Quadrant, Appendices, Vol II of II       Corp.
26 May 88   EPA Letter to Base Transmitting          Seid, Raymond
            Comments on Revised Basewide RI/FS Work  EPA Region  IX
            Plan of Apr 88
                                                                138

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORF.  AUTHOR
      FILE
      NUMBER
27 May 88   CDHS Letter to Base Transmitting Staff
            Review of Basewide RI/FS Work Plan of
            Apr 88
                                         Wang,  David
                                         California
                                         Department of Health
                                         Services
       139
23 Jun 88   Base Letter to CDHS Transmitting Well
            Installation Procedures Used for Test
            Wells 12-18
                                         Amerasinghe, S
                                         93 CSG/CVE
Felix  142
01 Jul 88   IT Corp. Letter to Base Transmitting
            Responses to EPA and CDHS Comments on
            RI/FS Work Plans of Apr 88
                                         IT Corp.
       147
06 Jul 88   IT Corp. Response to CDHS Comments on
            RI/FS Work Plans, Apr 88
                                         IT Corp.
       ISO
14 Jul 88   EPA Letter to Base Transmitting
            Documentation Requirements for Data
            Validation of Non-CLP Laboratory Data
            for Organic and Inorganic Analysis
                                         Seid,  Raymond
                                         EPA Region IX
       151
15 Jul 88   CDHS Letter to Base Encouraging
            Implementation of Toxic Waste Site
            Characterization Phase of RI/FS, Apr 88
                                         Wang,  David
                                         California
                                         Department of Health
                                         Services
       152
18 Jul 88   Base Letter  to EPA Transmitting Minutes
            from 03 Jun  88 Meeting on RI/FS Work
            Plans and Minutes  from Subsequent
            Conference Calls on  14 and 27 Jun 88
                                         Amerasinghe, S
                                         93 BMW/CVE
Felix  154
19 Aug 88   CDHS Letter  to Base  Regarding Receipt
            and Review of  18  Jul 88  Transcript of
            03 Jun  88  Meeting on RI/FS Work Plans
            and Subsequent Conference Calls on 14
            and 27  Jun 88
                                         Hang, David
                                         California
                                         Department of Health
                                         Services
       155

-------
                           Castle AFB. CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
29 Aug 88   IT Corp. Letter to Martin Marietta
            Transmitting Final Clarifications of
            Regulatory Comments Received Jun 88 on
            Work Plan, Sampling Plan, Health and
            Safety Plan, and Quality Assurance
            Project Plan Submitted Apr 88 for
            Upcoming RI/FS
                                         Erikson,  Dwight 6
                                         IT Corp.
                       156
Sep 88      RI/FS, Quality Assurance Project Plan,
            Vol III of IV
                                         IT Corp.
                       128
01 Sep 88   EPA Letter to Base Regarding Failure to  Anderson, Julie
            Receive Addendum to Work Plan            EPA Region IX
            Addressing Comments in Lieu of Revised
            Work Plan
                                                               159
14 Sep 88   Newspaper Article,  "TCE Evaluation
            Programs Under Way  at CAFB"
                                         The Atwater Signal
                       165
15 Sep 88   Newspaper Article:  "Please Output for
            Bill K" Regarding Air Force Article in-
            Signal, 14 Sep  88 "TCE Evaluation Under
            Way at Castle"
                                         Burke,  William J
                       163
Oct 88      EPA Letter to Base  Concerning Location
            of City of Atwater  Proposed Production
            Well
                                         Anderson,  Julie
                                         EPA Region IX
                       903
10 Oct 88   EPA Memorandum Regarding Review of
            Groundwater Documents
                                         Joma,  Hannibal
                                         EPA Region IX
                       909
19 Oct 88   Geo/Resource  Consultants Letter to EPA
            Regarding Review of  Letter to Martin
            Marietta Concerning  Clarifications of
            Responses to  EPA and ODHS Comments on
            Work  Plan
                                         Tryhorn,  Alan D
                                         Vanek,  Eva
                                         Geo/Resource
                                         Consultants, Inc.
                       169
                                      10

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
27 Oct 88   Preliminary Health Assessment
                                         Agency for Toxic
                                         Substances and
                                         Disease Registry
                       170
28 Oct 88   EPA Letter to City of Atwater Regarding  Anderson,  Julie
            Location of Proposed Production Well     EPA Region IX
                                                               908
31 Oct 88   EPA Letter to Base Regarding Completion  Flaherty,  Michael S
            of Review of QAPP for Work Plan          EPA Region IX
                                                               171
22 Nov 88   EPA Letter to Base Concerning Measures
            Taken to Mitigate Exposure to TCE
            Contaminated Water at Castle Mobile
            Home Park
                                         Flaherty,  Michael S
                                         EPA Region IX
                       902
Dec 88
RI/FS,  Work Plans, Addendum
                                                     IT Corp.
                       176
26 Jan 89   Newspaper Article, "Mobile Home Park
            Taps City Water"
                                         De La Cruz,  Mike
                                         The Atwater Signal
                       334
08 Feb 89   Newspaper Article, "H2O Spells
            Happiness for Park Residents"
                                         De La Cruz,  Mike
                                         The Atwater Signal
                       172
28 Feb 89   TCE Sampling Analysis Data
                                         California Water
                                         Labs.
                       187
10 May 89   Martin Marietta Letter to CDHS
            Regarding Addendum to RI/FS Work Plan
                                         Loyd,  John R
                                         Martin Marietta
                                         Energy Systems, Inc.
                       203
29 Jun 89   Newspaper Article: "Family Sues AF Over  McCarthy,  Charles
            Tainted Well"                            The Fresno Bee
                                                                209
                                     11

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATS
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
20 Jul 69   EPA Letter to Base Transmitting
            Comments Concerning Changes to
            Groundwater Sampling Events and Soil
            Boring Locations
                                         Flaherty,  Michael S   213
                                         EPA Region IX
10 Aug 89   EPA Letter to Base Regarding Ongoing RI  Flaherty,  Michael S   217
            Activities                               EPA Region IX
15 Sep 89   Geo/Resource Consultants Letter to EPA   Vanek,  Eva
            Regarding Review of Recent Water Level  'Tryhorn,  Alan D
            Data for Monitoring Wells                Geo/Resource
                                                     Consultants, Inc.
                                                               221
20 Sep 89   CRWQCB Letter to Base Regarding Review   Mosbacher,  Michael H  223
            of GAC Filtration Pump Test Results      California Regional
                                                     Water Quality
                                                     Control Board
16 Oct 89   Base Letter to HQ SAC Regarding RPM
            Meeting, 20 Sep 89
                                         Chan,  Arthur D
                                         93 BMW/CVE
                      225
03 Nov 89   Boyle Engineering Letter to Base         Reitz,  Mark           228
            Transmitting Letter Report Regarding 72  Boyle Engineering.
            Hour Pump Test                           Corp.
21 Nov 89   Base Letter to CDHS Transmitting 3rd  .  Bernier,  David R
            Quarter Results from Production Wells    93 MG/SGPB
            5, 6, 9, 10, and 11 for Review
                                                               23O
28 Nov 89   RI/FS, SOW for Step 3 Tasks
                                         Martin Marietta       369
                                         Energy Systems, Inc.
01 Dec 89   Base Letter to Resident Regarding
            Drinking Hater Samples
                                         Oyelowo, Layi A
                                         93 CSG/EM
                      232
                                     12

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
22 Dec 89   Base Letter to EPA and CDHS
            Transmitting RPM Meeting Minutes of
            RI/FS, Nov 89
                                         Chan, 'Arthur D
                                         93 CSG/EM
                      239
03 Jan 90   Certificate of Analysis, CAC Title 22    California Water
            Drinking Water Compliance                Labs
                                                               242
09 Feb 90   Martin Marietta Letter to Base
            Transmitting Minutes of RI/FS Review
            Meeting, 25 Jan 90
                                         Loyd,  John R
                                         Martin Marietta
                                         Energy Systems, Inc.
                      251
28 Feb 90   Base Letter to EPA and CDHS Regarding    Chan,  Arthur D
            Agenda for Next RPM Meeting              93 CSG/EM
                                                               255
07 Mar 90   RI/FS, Minutes of Project Status
            Meeting
                                         93 BMW/PA
                      257
21 Mar 90   CDHS Letter to Base Regarding Rationale  Mosbacher, Michael H  259
            for MW 713 and 714 Placements            California Regional
                                                     Water Quality
                                                     Control Board
23 Mar 90   CDHS Letter to Base Regarding Rationale  O'Kane, John A, Jr
            for Locating MW 713 and 714 in Order to  California
            Determine Potential TCE Source Areas     Department of Health
                                                     Services
                                                               260
06 Apr 90   EPA Letter to Base Confirming Agreement  Flaherty, Michael S
            with Rationale Provided by Air Force     EPA Region IX
            for Locating MW 713 and 714
                                                               264
09 Apr 90   Base Letter to EPA and CDHS
            Transmitting Minutes of Project
            Managers' RI/FS Status Meeting, 07 Mar
            90
                                         Ridenour, Charles B
                                         93 CSG/EM
                      265
                                     13

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
17 Apr 90   Base Letter to EPA and CDHS
            Transmitting Agenda for Next RPM
            Meeting, Technical Memo for Proposed
            Pilot Treatment Plant System for
            Review, and Map of Meeting Place
                                         Chan,  Arthur D
                                         93 CSG/EM
                       269
25 Apr 90   Base Letter Transmitting Minutes of TRC  93 CSG/EM
            Meeting, 25 Apr 90
                                                               273
02 May 90   Martin'Marietta Letter to Base           Loyd, John R
            Transmitting Minutes of 24 Apr 90 RI/FS  Martin Marietta
            Project Status Review Meeting            Energy Systems, Inc.
                                                               272
18 May 90   MID Letter  to Base Regarding Request
            for Use of  Casad Canal Right of Way to
            Drill/Test  for Monitoring Wells
                                         Reta,  Tom
                                         Merced Irrigation
                                         District
                       277
23 May 90   Base Letter  to  EPA and CDHS Regarding
            Next RPM Meeting
                                         Chan,  Arthur D
                                         93 CSG/EM
                       278
30 May 90   CDHS Letter  to Base Regarding Comments
            on Technical Memorandum for Proposed
            Long Term  Pumping Test             *
                                         O'Kane,  John A, Jr
                                         California
                                         Department of Health
                                         Services
                       283
31 May 90   Base Letter Transmitting RPM Meeting
            Minutes,  31 May 90
                                         Chan,  Arthur D
                                         93 CSG/EM
                       284
31 May 90   CDHS  Letter to DoD Transmitting DSMOA
                                         Kizer, Kenneth W
                                         California
                                         Department of Health
                                         Services
                       359
Jun 90       SOW,  TCE Filtration System for Wallace   93 CES/CEVR
             Road Residents
                                                                 72
                                      14

-------
DOC.
DATE
                          Caetle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
Jun 90      Base Letter to Residents Regarding       Sassaman, Brian L,
            Monthly TCE Samples Taken from Drinking  Lt
            Water                                    93 MG/SGPB
                                                               287
Jun 90      Base Letter to Residents Regarding
            Monthly TCE Samples Taken at OT-30 to
            Monitor Drinking Water Quality
                                         Sassaman,  Brian L,
                                         Lt
                                         93 MG/SGPB
 288
Jun 90      Base Letter to Resident Regarding
            Installation of GAC Filter at OT-30 to
            Remove TCE
                                         Sassaman, Brian L,
                                         Lt
                                         93 MG/SGPB
 289
Jun 90      Base Letter to Resident Regarding        Sassaman, Brian L,
            Installation of GAC Filter at Residence  Lt
            to Remove TCE                            93 MG/SGPB
                                                               290
Jun 90      Base Letter to Resident Regarding
            Monthly TCE Samples Taken at Residence
            to Monitor Drinking Water Quality
                                         Sassaman, Brian L,
                                         Lt
                                         93 MG/SGPB
Jun 90      Base Letter to Resident Regarding
            Monthly TCE Samples Taken at Residence
            to Monitor Drinking Water Quality
                                         Sassaman, Brian L,
                                         Lt
                                         93 MG/SGPB
 293
Jun 90      Base Letter to Resident Regarding
            Installation of GAC Filter at OT-30 to
            Remove TCE
                                         Sassaman, Brian L,
                                         Lt .
                                         93 MG/SGPB
 294
Jun 90      Base Letter  to Paul Harrison Co.
            Regarding Water Sample Collected from
            Well by Bioenvironmental Engineering
                                         Sassaman, Brian L,
                                         Lt
                                         93 MG/SGPB
 295
Jun 90      Base Letter  to Residents Regarding
            Water Sample Collected from Well by
            BioEnvironmental Engineering
                                         Sassaman, Brian L,
                                         Lt
                                         93 MG/SGPB
 299
                                     IS

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
11 Jun 90   Base Letter to EPA and CDHS
            Transmitting Meeting Agenda for Next
            RPM Meeting
                                         Chan,  Arthur D
                                         93 CSG/EM
                       301
29 Jun 90   Base Letter to EPA and CDHS
            Transmitting Draft Work Plan II for
            Review and Comment
                                         Chan,  Arthur D
                                         93 CSG/EM
                       308
Jul 90      Base Letter Regarding TRC Meeting        93 BMW/PA
            Minutes with Talking Paper, 14 Jun 90
                                                               303
17 Jul 90   RPM Meeting Minutes, 22 Jun 90 and
            Meeting Agenda, 24 Jul 90
                                         Chan,  Arthur D
                                         93 CSG/EM
                      312
30 Jul 90   Base Letter to Resident Regarding
            Merced Union High School Site
                                         Oyelowo,  Layi A
                                         93  CSG/EM
                      314
06 Aug 90   RPM Meeting Minutes, 24 Jul 90
                                         Chan,  Arthur D
                                         93 CSG/EM
                      320
08 Aug 90   EPA Letter to Base Regarding Need for
            TCE Removal Action
                                         Work,  Michael
                                         EPA Region IX
                       321
13 Aug 90   RPM Meeting Agenda, 16 Aug 90
                                         Chan,  Arthur D
                                         93 CSG/EM
                       325
22 Aug 90   Internal Martin Marietta Letter
            Transmitting SOW for Step 3 Tasks,
            Revision 2
                                         Loyd,  John R
                                         Martin Marietta
                                         Energy Systems, Inc.
                       326
31 Aug 90   EPA Letter to Base Regarding Completion  Work, Michael
            of Review of Draft RI/FS Work Plan No    EPA Region IX
            2, Jul  90
                                                               329
                                     16

-------
                          Castle AFB. CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or            FILE
DATE        SUBJECT OR TITLE                         CORP. AUTHOR         NUMBER
Sep 90      SOW, Maintenance and Servicing of Three  93 CSG/DEEV           907
            Existing Culligan Activated Carbon
            Water Filtration Systems


20 Sep 90   Base Letter to EPA Transmitting Agenda   Baker,  Thomas R,      336
            for Meeting 26-27 Sep 90                 LtCol
                                                     93 CSG/EM
27 Sep 90   RI/FS, Project Status Meeting Minutes,   93 CSG/EM             337
            26-27 Sep 90


28 Sep 90   RPM Meeting Minutes, 16 Aug 90           Chan,  Arthur D        338
                                                     93 CSG/EM


Oct 90      Environmental Update                     93 BMW/PA             340


Oct 90      Ambient Air Monitoring Report            California           ICC-3
                                                     Department of Health
                                                     Services
12 Oct 90   Base Letter to EPA and CDHS              Chan,  Arthur D        345
            Transmitting Draft Final of Work Plan 2  93 CSG/EM


16 Oct 90   RPM Meeting Minutes, 26-27 Sep 90        Chan,  Arthur D        348
                                                     93 CSG/EM
24 Oct 90   RPM Meeting Agenda, 30 Oct 90            Chan,  Arthur D        350
                                                     93 CSG/EM


24 Oct 90   EPA Letter to Base Regarding Failure to  Work,  Michael         351
            Submit Draft Final Work  Plan No 2        EPA Region IX
            Before 15 Oct 90
                                      17

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
02 Nov 90   EPA Letter to Base Transmitting
            Comments on RI/FS Long Term Sampling
            Program
                                         Work,  Michael
                                         EPA Region IX
 357
15 Nov 90   Soil Remediation Report
                                         Horizon Technologies  361
Dec 90      RFA, Facility Assessment Report
                                         California            373
                                         Department of Health
                                         Services
05 Dec 90   TRC Meeting Minutes with Slides and
            Talking Papers
                                         Vician, Todd M B, Lt  377
                                         93 BMW/PA
11 Dec 90   RPM Meeting Agenda, 18 Dec 90
                                         Oyelowo, I
-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
11 Feb 91   RPM Meeting Minutes, 23-24 Jan 91
                                         Chan,' Arthur D
                                         93 CSG/DEV
                      398
01 Mar 91   TRC Meeting Minutes, 23 Jan 90
                                         Vician, Todd M B, Lt  407
                                         93 BMW/PA
06 Mar 91   RPM Meeting Agenda, 13 Mar 91
                                         Baker,  Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      408
26 Mar 91   Base Letter to EPA Regarding Naming of   Baker, Thomas R,
            OUs                                      LtCol
                                                     93 CSG/DEV
                                                               415
Apr 91
Castle AFB Environmental Update
93 BMW/PA
 417
23 Apr 91   Base Letter Transmitting Minutes of      Baker, Thomas R,
            RI/FS Project Status Meeting, 13 Mar 91  LtCol
                                                     93 CSG/DEV
                                                               427
29 Apr 91   RPM Meeting Agenda, 08 May 91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      431
15 May 91   EPA Letter  to Base Transmitting Meeting  Work, Michael
            Minutes, 23-24 Jan 91                    EPA Region IX
                                                               443
16 May 91   Base Letter to Martin Marietta           Baker, Thomas  R,
            Transmitting EPA and CRWQCB Comments on  LtCol
            Jan RPM Meeting Minutes                  93 CSG/DEV
                                                               445
21 May 91   CRWQCB Letter  to Base  Regarding
            Completion of  Review of  Proposed
            Schedule Changes for OU-2 and Basewide
            RI/FS
                                         Mosbacher, Michael H   446
                                         California Regional
                                         Water Quality
                                         Control Board
                                      19

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Repor.t:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
22 May 91   EPA Letter to Base Transmitting Draft    Work. Michael
            RPM Meeting Minutes, 08 May 91           EPA Region IX
                                                                447
29 May 91   Base Letter to IT Corp Transmitting      Baker, Thomas R,
            Comments on Draft RPM Meeting Minutes,    LtCol
            08 May 91                                93 CSG/DEV
                                                                452
01 Jun 91   TRC Meeting Minutes, 24 Apr 91
                                         Leong,  Linda L, Maj    454
                                         93 BMW/PA
27 Jun 91   RPM Meeting Minutes, 27 Jun 91
                                         93 CSG/DEVR
                       464
Jul 91      Data Report, 15 VOC Probes Drilled in    IT Corp.
            OT-30 Area
                                                                467
12 Jul 91   Base Letter to EPA and CDHS              Baker, Thomas R,
            Transmitting Draft RPM Meeting Minutes,  LtCol
            28 Jun 91                                93 CSG/DEV
                                                                472
12 Jul 91   Base Letter to EPA and CDHS Regarding    Baker, Thomas R,
            Failure to Identify Requirement to       LtCol
            Consultant Preparing RI/FS Report, OU-2  93 CSG/DEV
                                                                473
18 Jul 91   EPA Letter to Base Regarding Late
            Receipt of Draft  Risk Assessment for
            OU-2 and FFA Schedule
                                         Work,  Michael
                                         EPA Region IX
                       475
Aug 91      Draft Soil Management Plan for Haste in  COM Federal Programs  483
            Drums and RI Derived Waste Originating   Corp.
            from VOC Probes
08 Aug 91   Base Letter Transmitting  Final RPM
            Meeting Minutes.  27  Jun 91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                       488
                                      20

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
                     FILE
                     NUMBER
15 Aug 91   Newspaper Article: "CRWQCB Public
            Hearing and Notice of Application for
            Waste Discharge Requirements"
                                         Pearson, J Lawrence
                                         The Merced Sun Star
                      490
20 Aug 91   Base Letter to EPA Transmitting Draft
            RPM Meeting Minutes, 01 Aug 91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      491
26 Aug 91   Base Letter to CDHS Transmitting
            Summary Sheet of Monthly TCE Results
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      430
Sep 91
RI/FS, Draft Report, OU-2
Metcalf & Eddy, Inc.  495
04 Sep 91   EPA Comments on Draft RPM Meeting
            Minutes, 01 Aug 91
                                         Work, Michael
                                         EPA Region IX
                      498
11 Sep 91   CDHS Letter to Base Regarding Review of  Wang, David
            Draft Soil Management Plan for Wastes    California
            in Drums and RI Derived Waste            Department of Health
            Originating from VOC Probes, Aug 91      Services
                                                              1021
16 Sep 91   Base Letter to EPA Transmitting Final
            RPM Meeting Minutes, 01 Apr 91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      500
17 Sep 91   EPA Letter to Base Transmitting          Work, Michael
            Preliminary Comments on Draft RI/FS for  EPA Region IX
            OU-2
                                                                502
25 Sep 91   Base Letter to EPA Transmitting Draft
            RPM Meeting Minutes, 17 Sep  91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                       SOS
Oct 91      Draft Work Plan/Technical Memorandum,
            Scoping Memorandum for OU-2
                                         Metcalf & Eddy,  Inc.   506
                                      21

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
            SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NtJMBBR
09 Oct 91   Base Letter to CDM Transmitting          Baker,' Thomas R,
            Comments on RPM Meeting Minutes, 17 Sep  LtCol
            91                                       93 CSG/DEV
                                                                           510
15 Oct 91   CDTSC Letter to Base Regarding           Wang, David
            Completion of Review of Draft RI/FS for  California
            OU-2                                     Department of Toxic
                                                     Substances Control
                                                                           516
15 Oct 91   EPA Letter to Base Regarding Comments    Work,  Michael
            on Draft RI/FS for OU-2                  EPA Region IX
                                                                            517
21 Oct 91   CDTSC Letter to Base Regarding Revised   Wang,  David
            Comments for Draft RI/FS for OU-2        California
                                                     Department of Toxic
                                                     Substances Control
                                                                            521
21 Oct 91   CRWQCB Letter to Base Regarding
            Completion of Review of Draft Final
            RI/FS for OU-2
                                                     Mosbacher,  Michael H  522
                                                     California Regional
                                                     Hater Quality
                                                     Control Board
25 Oct 91   EPA Letter to Base Regarding
            Completeness of RI/FS for OU-2
                                                     Work,  Michael
                                                     EPA Region IX
                      524
31 Oct 91   Summary of Conference Call Between
            Representatives to Discuss Critical
            Issues from EPA Comments on Draft OU-2
            RI/FS Report
                                                     Wilder,  William L
                                                     Oak Ridge National
                                                     Laboratory
                       529
19 Nov 91   Base Letter to  EPA Transmitting Draft
            RPM Meeting Minutes, 22 Oct 91
                                                     Baker,  Thomas R,
                                                     LtCol
                                                     93 CSG/DEV
                       535
                                     22

-------
DOC.
DATE
                          Castle AFB, CA  - AR DOCUMENTS
                                     Sorted by:
                            Date of  Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
20 Mov 91   EPA Letter  to Base Regarding Review and  Work, Michael
            Comment of  Action Plan  for Additional    EPA Region IX
            Domestic Well Sampling  Southwest of
            Base
                                                               537
22 Nov 91   Scoping Meeting Minutes on OU-2 Work
            Plan, 22 Nov  91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      542
Dec 91      RI/FS, Draft Final BRA, Vol I of  II,
            OU-2
                                         Metcalf & Eddy, Inc.  545
Dec 91      RI/FS, Draft  Final BRA, Vol II of  II,
            OU-2
                                         Metcalf & Eddy, Inc.  546
03 Dec 91   EPA Letter  to Base Transmitting     ,_
            Comments  on Draft Work  Plan/Technical
            Memorandum/Scoping Memorandum  for OU-2
                                         Work, Michael
                                         EPA Region IX
                      547
06 Dec 91   CDTSC  Letter  to Base Regarding Receipt
            and Review of EPA Comments Concerning
            OU-2 Work  Plan/Technical Memorandum
                                         O'Kane, John A, Jr
                                         California
                                         Department of Toxic
                                         Substances Control.
                      550
16 Dec 91   EPA  Letter "to  Base  Regarding Review of   Work, Michael
            Draft  Final  RI/FS for OU-2             ,  EPA Region IX
                                                               SS5
16 Dec 91   Base  Letter to EPA Transmitting  Final    Baker, Thomas R,
            RPM Meeting Minutes.  22  Oct  91           LtCol
                                                     93 CSG/DEV
                                                                556
18 Dec 91    EPA Letter to Base Regarding  Review of   Work, Michael
             Draft Proposed Plan for OU-2             EPA Region IX
                                                                557
                                      23

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP.  AUTHOR
FILE
NUMBER
18 Dec 91   TRC Meeting Minutes, 13 Nov 91
                                         Kehoe,  Michael J,
                                         Col
                                         93 BMW/CV
 558
20 Dec 91   CDTSC Letter to Base Requesting 30 Day
            Extension to Comment and Response
            Period in Order to Resolve Differences
            with Regard to Content of Draft Final
            RI/FS and Proposed Plan, OU-2
                                         Hang,  David
                                         California
                                         Department of Toxic
                                         Substances Control
 559
20 Dec 91   CDTSC Letter to EPA Requesting 30 Day
            Extension to Comment and Response
            Period  in Order to Resolve Differences
            With Regard to Content of Draft Final
            RI/FS and Proposed Plan, OU-2
                                         Wang,  David
                                         California
                                         Department of Toxic
                                         Substances Control
 561
Jan 92       RI/FS,  Draft  Final BRA, Vol I of II,.
             OU-2
                                         Metcalf & Eddy, Inc.  564
Jan 92       RI/FS,  Draft  Final BRA, Vol II of II,
             OU-2
                                         Metcalf & Eddy. Inc.  565
07 Jan  92    CDTSC Letter  to  Base Regarding Comments  Mosbacher, Michael. H  566
             on Draft  Final RI/FS and Proposed Plan,  O'Kane, John A,  Jr
             OU-2                                 -    California
                                                     Department of  Tcxic
                                                     Substances Control
09 Jan  92    EPA Letter to Base Requesting Delivery
             of Revised RI/FS Prior  to.Expiration
             Date of 21 Jan 92 and Draft Final
             Proposed Plan by 15 Feb 92
                                         Work, Michael
                                         EPA Region IX
 567
 16  Jan 92    EPA Comments on Draft  Work  Plan for
             Groundwater Plume Characterization,
             Scoping Memorandum for OU-3,  Dec 91
                                         EPA Region IX
 544
                                      24

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
21 Jan 92   EPA Letter to Base Transmitting Review   Work, Michael
            and Comment on Draft RPM Meeting         EPA Region  IX
            Minutes, 17 Dec 91
                                                                569
22 Jan 92   Base Letter to Different Residents
            Regarding TCE Sampling Near Their
            Residences to Monitor Quality of
            Drinking Water
                                         Baker,  Thomas R,
                                         LtCol
                                         93 CSG/DEV
 571
22 Jan 92   Base Letter  to Resident Regarding
            Monthly TCE  Samples Taken to Monitor
            Quality of Drinking Water
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
 572
22 Jan 92   Base Letter to CDHS Transmitting
            Monthly TCE Test Results for Months of
            Oct, Nov, and Dec  91
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
 573
22 Jan 92   Base Letter  to  CDTSC Transmitting
            Summary Sheet of Monthly TCE Results
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
 574
22 Jan 92   Base Letter  to  Resident Transmitting
            TCE Samples  Taken to Monitor Drinking
            Water  Quality
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
 576
22 Jan 92   Base Letter  to EPA Transmitting Summary  Baker, Thomas  R,
            Sheet  of  Monthly TCE  Results             LtCol
                                                     93 CSG/DEV
                                                                577
22 Jan 92   Base  Letter to EPA Regarding Amendments  Baker, Thomas  R,
            to Draft  Filial RI/FS  for OU-2            LtCol
                                                     93 CSG/DEV
                                                                578
27 Jan 92   EPA Letter to Base Transmitting
            Comments on 22 Jan 92  Revisions  to
            Draft  Final RI/FS,  OU-2
                                         Work, Michael
                                         EPA Region  IX
 5B2
                                      25

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or            FILE
DATE        SUBJECT OR TITLE                         CORP.  AUTHOR         NUMBER
29 Jan 92   CDTSC-Letter to Base Regarding Review    O'Kane,  John A, Jr    585
            of Draft Final RI/FS and Proposed Plan   California
            for OU-2, Jan 92                         Department of Toxic
                                                     Substances Control
30 Jan 92   CRWQCB Letter to Base Regarding Review   Vorster,  Antonia K J  586
            of Draft Final RI/FS, Jan 92 and         California Regional
            Proposed Plan, 27 Nov 92 for OU-2        Water Quality
                                                     Control Board
30 Jan 92   CDTSC Letter to Base Requesting for      Wang,  David           587
            Extension of IAG Schedule, 29 Jan 92     California
                                                     Department of Toxic
                                                     Substances Control
Feb 92      VOC Probe Results                        IT Corp.               589


06 Feb 92   EPA Letter to Base Regarding Receipt of  Work,  Michael         595
            Letter Requesting Extensions to FFA      EPA Region IX
            Schedules for Draft Final RI/FS for
            OU-2, Draft Work Plan for OU-3, and
            Draft Final Proposed Plan for OU-2
                                              *

10 Feb 92   CDTSC Letter Regarding Base Request for  O'Kane,  John A, Jr    597
            Identification of Applicable, Relevant   California
            and Appropriate Requirements for         Department of Toxic
            Remediation of Groundwater            ,  Substances Control
            Contamination at OU-2
11 Feb 92   California Department of Public Works    Fillebrown, Paul A    60O
            Letter to CDHS Regarding ARARs for       California
            Remediation of Groundwater               Department of Public
            Contamination for OU-2                   Works
12 Feb 92   Base Letter  to EPA Regarding Working     Baker, Thomas R,       601
            Session and  RPM Meeting Minutes, 04 Feb  LtCol
            92                                       93 CSG/DEV
                                      26

-------
DOC.
DATE
                          Castle APB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
12 Feb 92   Newspaper Article: "Carbon Filters Help  The Atwater Signal     602
            Castle with Groundwater Cleanup"
13 Feb 92   Newspaper Article: "Castle Clean-up
            Steps Forward"
                                         The Winton Times
                      605
14 Feb 92   MID Letter to Base Regarding Water       Selb, E C Ted, III
            Quality Results, DA-4 and Wallace Road   Merced Irrigation
                                                    . District
                                                               606
14 Feb 92   Base Letter to EPA Regarding Proposed
            Plan for OU-2
                                         Baker, Thomas R,
                                         LtCol
                                         93 CSG/DEV
                      607
21 Feb 92   EPA Letter to Base Regarding Delinquent  Work, Michael
            Draft Final Proposed Plan for OU-2  .     EPA Region IX
                                                               608
24 Feb 92   Base Letter to EPA Transmitting Final    Baker, Thomas R,
            Minutes, RPM Meeting, 17 Dec 91          LtCol
                                                     93 CSG/DEV
                                                               610
25 Feb 92   EPA Letter to Base Regarding Draft
            Minutes of RPM Meeting, 04 Feb 92
                                         Work, Michael
                                         EPA Region IX
                      612
02 Mar 92   EPA Letter to Base Regarding RD for
            OU-2
                                         Work, Michael
                                         EPA Region IX
                      614
04 Mar 92   CRWQCB Letter to Base Regarding Draft    Izzo. Victor J
            Work Plan and Field Sampling Plan,       California Regional
            Groundwater Plume Characterization OU-3  Water Quality
                                                     Control Board
                                                               615
05 Mar 92   Newspaper Article:  "Castle Cleans
            Groundwater"
                                         The Atwater New
                                         Times
                       617
                                      27

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
10 Mar 92   CRWQCB Letter to CDTSC Regarding ARARs
            for OU-2
                                         Izzo,  Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       621
11 Mar 92   EPA "Letter to Base Transmitting          Work,  Michael
            Comments on Draft Final Proposed Plan    EPA Region IX
            for OU-2
                                                               622
15 Mar 92   Castle AFB Environmental Update
                                         93 BMW/PA
                       626
17 Mar 92   EPA Letter to Base Regarding Cal EPA
            Letters on RI/FS for OU-2
                                         Work,  Michael
                                         EPA Region IX
                       627
23 Mar 92   CDTSC Comments to Base Regarding Draft
            Final Proposed Plan for OU-2
                                         O'Kane,  John A, Jr
                                         California
                                         Department of Toxic
                                         Substances Control
                       629
24 Mar 92   CRWQCB Letter to Base Regarding Draft
            Final Proposed Plan for OU-2
                                         Izzo,  Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       630
30 Mar 92   EPA Letter to Base Regarding Public
            Comment Period for OU-2
                                         Work,  Michael
                                         EPA Region IX
                       633
30 Mar 92   CRWQCB Letter to Base Regarding Data
            Needs for ROD, OU-2
                                         Izzo,  Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       634
Apr 92      Proposed  Plan  for  Remediation of
            Groundwater Contamination in Area of
            Wallace Road and DA-4
                                         93 CES/DEVR
                       638
                                      28

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or            FILE
DATE        SUBJECT OR TITLE                         CORP. AUTHOR         NUMBER
01 Apr 92   EPA Letter to Base Regarding Proposed    Work, Michael         640
            Plan for OU-2                            EPA Region IX
02 Apr 92   Newspaper Article: "Lack of Money for    The Winton Times      641
            Water Clean-up"
08 Apr 92   EPA Letter to Base Regarding EPA Review  Work, Michael         646
            of Aerial Photo Analysis and Draft CSA   EPA Region IX
            Report


16 Apr 92   EPA Letter to Base in Order to Clarify   Anderson, Julie       648
            EPA Positions on OU-2                    EPA Region IX
17 Apr 92   EPA Letter to Base Regarding Draft       Work, Michael         649
            Proposed Plan Fact Sheet, Public         EPA Region IX
            Comment Period and ROD, OU-2
29 Apr 92   Newspaper Article:  "Base Facilities to   Sanders, Tammy S      653
            Tie into Atwater Waste Water Treatment   The Atwater Signal
            Plant"
08 May 92   Newspaper Article: "Cleanup Plan Urged"  The Modesto Bee  _.    663


12 May 92   Newspaper Article: "Public Meeting       The Merced Sun Star   665
            Planned"                              ,
13 May 92   Base Letter to EPA Regarding RPM         Baker, Thomas R,      666
            Meeting, 14 May 92        .               LtCol
                                                     93 CSG/DE


14 May 92   Newspaper Article: "Castle's Proposed    The Atwater New       667
            Water Clean-up Plan"                     Times


29 May 92   EPA Letter to Base Regarding Draft ROD   Anderson, Julie       676
            for OU-2 and Requested Extension         EPA Region IX
                                     29

-------
DOC.
DATS
                          Castle AFB,  CA -  AR DOCUMENTS
                                    Sorted  by:
                            Date of  Report:   04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
03 Jun 92   CDTSC .Comments to Base  on Proposed Plan Austreng,  James C
            for OU-2                                California
                                                    Department of Toxic
                                                    Substances Control
                                                               682
03 Jun 92   CRWQCB Comments to Base on Proposed
            Plan for OU-2
                                         Izzo,  Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       683
15 Jun 92   Draft ROD,  OU-2
                                         EPA Region IX
                       681
16 Jul 92   SAP Letter to EPA Region IX and CDTSC
            Regarding Dispute Resolution
                                         Vest,  Gary D
                                         Deputy Assistant
                                         Secretary of the Air
                                         Force
                       688
29 Jul 92   Newspaper Article:  "Atwater in Line for  De  La Cruz,  Mike
            Big Federal Grant,  $1.5 Million Would    The Merced Sun Star
            Pay to Connect Castle AFB Sewer Lines
            to Treatment Plant"
                                                               700
05 Aug 92   EPA Letter to Base, CRWQCB,  and CDTSC    Work,  Michael
            Regarding Review of Draft ROD for OU-2    EPA Region IX
                                                               702
07 Aug 92   Base Letter to EPA Transmitting ROD
            Responsiveness Summary,  OU-2
                                         Parker,  Scarlette P,
                                         TSgt
                                         93 BMW/CVE
                       703
11 Aug 92   CRWQCB Letter to EPA Regarding Review
            Comments Due Date for Draft ROD for
            OU-2
                                         Izzo,  Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       707
                                     30

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
11 Aug 92   CDTSC Letter to EPA Regarding Draft ROD  Austreng, James C
            for OU-2 with Comments                   California
                                                     Department of Toxic
                                                     Substances Control
                                                               708
11 Aug 92   PRC.Letter to Base Transmitting          Scruggs, Mary
            Response to EPA Comments on Draft 100%   PRC Environmental
            Design Documents and Draft RA Work Plan  Management, Inc.
            for OO-l
                                                               709
13 Aug 92   Base Letter to EPA Concerning Comments   Hicks, Brad
            on Draft ROD, OU-2                       93 CES/DEVR
                                                               712
14 Aug 92   CRWQCB Letter to Base Transmitting
            Cpmments on Draft ROD, OU-2
                                         Izzo, Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                      713
IB Aug 92   EPA Letter to Base and Cal EPA           Work, Michael
            Requesting Review of Draft               EPA Region IX
            Responsiveness Summary for OU-2, 09 Sep
            92
                                                               715
03 Sep 92   CRWQCB Letter to Base Transmitting
            Comments on Draft OU-2 Responsiveness
            Summary
                                         Izzo, Victor J
                                         California Regional
                                         Water Quality
                                         Control Board
                       721
16 Sep 92   EPA Letter to Base. CDTSC, and CRWQCB
            Transmitting Draft Final ROD for OU-2
                                         Work, Michael
                                         EPA Region IX
                       726
21 Sep 92   EPA Letter to Base Regarding Draft
            Final ROD for OU-2 on Diskette
                                         Work, Michael
                                         EPA Region IX
                       728
                                      31

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
24 Sep 92   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John  R,  LtCol
            Regarding Retraction of Draft Final ROD  93 BMW/CVE
            for OU-2 (Reference EPA Letter, 16 Sep
            92)
                                                                730
25 Sep 92   EPA'Letter to Base Regarding Base
            Cleanup Information
                                         Takata, Keith
                                         EPA Region IX
                       732
26 Sep 92   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John  R,  LtCol   733
            Regarding Proposed FFA Schedule          93 BMW/CVE
Oct 92
Draft Final ROD, OU-2
93 CES/CEV
 739
02 Oct 92   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John R,  LtCol   197
            Regarding Transmission of Draft Final    93 SG/DE
            ROD for OU-2
09 Oct 92   EPA Letter to Base Transmitting Draft    Work, Michael
            Meeting Minutes, 16 Sep 92               EPA Region  XX
                                                                742
13 Oct 92   EPA Letter to Base Regarding Draft
            Proposed FFA Schedule.-
                                         Work, Michael
                                         EPA Region IX
                       743
21 Oct 92   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John  R,  LtCol   748
            Transmitting Proposed Agenda for RPM   ,  93 BMW/CVE
            Meeting, 04 Nov 92
23 Oct 92   Base Letter to EPA, CDTSC,- and CRWQCB
            Transmitting RPM Meeting Minutes, 16
            Sep 92
                                         Cole, John R,  LtCol   749
                                         93 BMW/CVE
29 Oct 92   EPA Letter to Base Regarding Draft
            Final ROD for OU-2
                                         Work, Michael
                                         EPA Region  IX
                       752
                                      32

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
02 Nov 92   Base Letter to EPA, CDTSC, and CRWQCB    Baker/ Thomas R,
            Regarding EPA's Comments on OU-2 Draft   LtCol
            Final ROD, 29 Oct 92                     93 CES/CEVR
                                                               759
04 Nov 92   RPM Meeting Minutes, 04 Nov 92
                                         Reith, Charles
                                         Jacobs Engineering
                                         Group, Inc.
                      761
05 Nov 92   CDTSC Letter to EPA and HQ ACC
            Regarding Dispute Resolution
                                        .Ward, Daniel T
                                         California
                                         Department of Toxic
                                         Substances Control
                      767
05 Nov 92   CRWQCB Letter to Base Regarding          Izzo, Victor J
            Approval of Building 84 Removal Action   California Regional
                                                     Water Quality
                                                     Control Board
                                                               768
09 Nov 92   Castle AFB Environmental Update
                                         93 BW/PA
                      769
09 Nov 92   Castle AFB Environmental Update
                                         93 BW/PA
                      784
20 Nov 92   E-    .tter to Base Regarding Draft       Work, Michael
            Pr-_.-r.iinary Accelerated  RD/RA Schedule   EPA Region IX
            for OU-2
                                                               772
25 Nov 92   EPA Letter to HQ ACC.  CDTSC, and CRWQCB  Takata, Keith
            Regarding Dispute  Resolution, ROD for    EPA Region IX
            OU-2
                                                               774
10 Dec 92   Newspaper Article:  "Castle AFB Receives  The Winton Times
            $21 Million  for Cleanup"
                                                                779
14 Dec 92   SOW, Title  I  Services for Groundwater
            Treatment,  OU-2  and Title II  Services
            for Groundwater  Treatment,  OU-1
                                         Jacobs Engineering
                                         Group, Inc.
                       946
                                      33

-------
                          Castle AFB,  CA -  AR  DOCUMENTS
                                    Sorted  by:
                            Date of Report:  04/25/96

DOC.                                                AUTHOR or            PILE
DATE        SUBJECT OR TITLE                        CORP.  AUTHOR         NUMBER
15 Dec 92   CRWQCB- Letter to Base Regarding Draft    Izzo,  Victor J        785
            Update of Monitoring and Reporting       California Regional
            Program of Board Order Number            Water  Quality
                                                     Control Board
16 Dec 92   Newspaper Article:  "Castle Gets  Cleanup  Parker,  Scarlette P,  786
            Funding"                                 TSgt
                                                     The Atwater Signal


05 Jan 93   TRC Meeting Minutes,  18 Nov 92            Bishop,  Raymond C,    788
                                                     Col
                                                     93  BW/CV
06 Jan 93   Base Letter to EPA,  CDTSC,  and CRWQCB    Cole,  John R, LtCol   789
            Transmitting Proposed Agenda for RPM     93 BW/CVE
            Meeting, 20 Jan 93


11 Jan 93   EPA Letter to Base Regarding Draft       Work,  Michael         790
            Quality Assurance Project Plan,  Nov 92   EPA Region IX.


12 Jan 93   EPA Letter to HQ ACC, CDTSC. and CRWQCB  Takata,  Keith         791
            Regarding Dispute Resolution, ROD for    EPA Region IX
            OU-2
14 Jan 93   CDTSC Letter to EPA Regarding Dispute    Wang,  David            792
            Resolution, ROD for OU-2              .   California
                                                     Department of Toxic
                                                     Substances Control
Feb 93      RD, Draft Work Plan, OU-2                Jacobs Engineering     798
                                                     Group, Inc.


Feb 93      Draft Conceptual Design Support          Jacobs Engineering     799
            Document Technical Memorandum for OU-2   Group, Inc.
                                     34

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
Feb 93      RI, Comprehensive Basewide Groundwater   Jacobs Engineering
            Health and Safety Plan                   Group, Inc.
                                                               959
03 Feb 93   Base Letters to Residents Regarding
            Sampling Results
                                         Baker,  Thomas R,
                                         LtCol
                                         93 CES/CEV
                      801
08 Feb 93   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John R, LtCol   803
            Regarding Draft Final RD/RA Schedule     93 BW/CVE
            for OU-2
09 Feb 93   EPA Letter to Base Regarding Draft
            Meeting Minutes, 20 Jan 93
                                         Work,  Michael
                                         EPA Region IX
                      805
19 Feb 93   CDTSC Letter to EPA Regarding Extension  Wang,  David
            of Review Period for OU-2          .„     California
                                                     Department of Toxic
                                                     Substances Control
                                                               813
23 Feb 93   Base Letter to EPA, CDTSC, and CRWQCB
            Documenting Phone Conversation on
            Approval of Contaminated Groundwater
            Disposal
                                         Baker,  Thomas R,
                                         LtCol
                                         93 CES/CEV
                      816
01 Mar 93   MCDH Letter to Resident Responding to
            Comments
                                         Palsgaard, Jeff H
                                         Merced County
                                         Department of Public
                                         Health
                       821
08 Mar 93   EPA Letter to MCDPH Regarding MCDPH
            Letters of Feb 9 and 11. 93
                                         Work,  Michael
                                         EPA Region IX
                       825
22 Mar 93   EPA Letter to HQ ACC, CDTSC, and CRWQCB  Takata, Keith
            Regarding Dispute Resolution, ROD for    EPA Region IX
            OU-2
                                                               835
                                     35

-------
                          Castle AFB, CA - AR DOCDMKMTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP.  AUTHOR
FILE
NUMBER
22 Mar 93   Base Letter to Residents Transmitting
            Results from Well Hater Sampling
                                         Baker, Thomas R,
                                         LtCol
                                         93 CES/CEV
 836
23 Mar 93   Newspaper Article: "Cleanup Efforts at
            Castle Continue"
                                         Lindsay, Alvie
                                         The Modesto Bee
 836
24 Mar 93   CDTSC Letter to EPA Regarding Extension  Wang,  David
            of Review Period for OU-2                California
                                                     Department of Toxic
                                                     Substances Control
                                                                839
01 Apr 93   Base Letter to Residents Transmitting
            Monthly TCE Samples
                                         Baker, Thomas R,
                                         LtCol
                                         93 CES/CEV
 843
07 Apr 93   HQ ACC Letter to EPA Region IX on
            Dispute Resolution, ROD for OU-2
            Regarding EPA Letter, 22 Mar 93
                                         Mogge, John w, Col
                                         HQ ACC/CEV
 847
14 Apr 93   EPA Letter to Base Regarding OU-2
            Conceptual Design Support Technical
            Memorandum
                                         Work,  Michael
                                         EPA Region IX
 851
23 Apr 93   EPA Letter to Resident Regarding
            Resident's Letter to Merced County
            Department of Public Health
                                         Work,  Michael
                                         EPA Region IX
 854
29 Apr 93   Base Letter to Resident Regarding Hell
            Sampling
                                         Baker, Thomas R,
                                         LtCol
                                         93 CES/CEV
 856
May  93      Draft  Final Conceptual Design Support
            Document Technical Memorandum for OU-2
                                         Jacobs Engineering
                                         Group, Inc.
  858
                                      36

-------
                          Castle AFB,  CA  - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or             FILE
DATE        SUBJECT OR TITLE         -                CORP. AUTHOR          NUMBER
10 May 93   Draft-RPM Meeting Minutes, 29 Apr 93     Watkiri, Geoff W        866
                                                     Jacobs Engineering
                                                     Group, Inc.
13 May 93   HQ ACC Letter to EPA Regarding Dispute   Mogge, John W, Col     871
            Resolution, ROD for OU-2                 HQ ACC/CEV
14 May 93   Base Letter to CRWQCB Regarding OU-2     Cole, John R, LtCol    872
            Waste Soil Disposal                      93 BW/CVE
18 May 93   Base Letter to CRKQCB Regarding OU-2     Cole, John R, LtCol    875
            Waste Water Disposal                     93 BW/CVE
21 May 93   EPA Letter to Base  Regarding Revised     Work, Michael,         878
            OU-2 Conceptual Design  Support           EPA Region  IX
            Technical Memorandum, May 93


26 May 93   HQ ACC Letter to EPA Regarding Dispute   Mogge, John W, Col     881
            Resolution, ROD for OU-2,  Cost to        HQ ACC/CEV
            Comply Summary
03 Jun 93   Base Letter to Jacobs  Regarding    *      Baker, Thomas R, _ .    890
            Disposition of Waste Generated by  OU-2   LtCol
            Activities                            .   93 BW/CVE
11 Jun 93   HQ ACC Letter to  EPA Regarding Dispute   Burnet, Gilbert N
            Resolution, ROD for OU-2                 HQ ACC/CEV
15 Jun 93   HQ ACC Letter  to EPA Regarding Dispute   Mogge, John  W,  Col      30
            Resolution,  ROD for OU-2,  Cost to       HQ ACC/CEV
            Comply Summary


22 Jun 93   EPA  Letter  to  HQ ACC, CDTSC,  and CRWQCB  Takata,  Keith         218
            Regarding Dispute Resolution,  ROD for   EPA Region IX
            OU-2
                                      37

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96

DOC.                                                 AUTHOR or             FILE
DATE        SUBJECT OR TITLE                         CORP. AUTHOR          NUMBER
22 Jun 93   Base Letter to CRWQCB Regarding          Baker, Thomas R,       219
            Temporary Shut Down of DA-4 and Wallace  LtCol
            Road                                     93 CES/CEV
29 Jun 93   CDTSC Letter to EPA Regarding Extension  Wang, David            258
            of Review Period for OU-2                California
                                                     Department of Toxic
                                                     Substances Control
12 Jul 93   Right of Entry Between Government and    Kotyk, Jack W          342
            Landowner                          .      AFBDA/OL
12 Jul 93   HQ ACC Letter to EPA Regarding Dispute   Mogge, John W, Col     346
            Resolution, ROD for OU-2, Cost to        HQ ACC/CEV
            Comply Summary


13 Jul 93   Base Letter to CRWQCB Regarding Summary  Baker, Thomas R,       380
            Sheet of All Monthly TCE Results         LtCol
                                                     93 CES/CEV
16 Jul  93   Base  Letter  to Resident Regarding Their  Baker, Thomas R,       400
            Culligan Water Filter                    LtCol
                                                     93 CES/CEV
30 Jul  93    Right  of Entry  for Environmental          93 CES/CEVR            457
             Testing and Monitoring


03 Aug  93    RPM Meeting Minutes, 22 Jul 93            Watkin,  Geoff  W       474
                                                      Jacobs  Engineering
                                                      Group,  Inc.


06 Aug  93    CRWQCB Letter to HQ ACC Regarding OU-2    Pearson,  J Lawrence   484
             Dispute Remaining Issues                  California Regional
                                                      Water Quality
                                                      Control Board
                                      3-8

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
09 Aug 93   Base Letter to Resident Transmitting     Fraher, Jeffrey T,    494
            Water Sample Results                     Maj
                                                     93 CES/CEV
09 Aug 93   EPA Letter to CRWQCB Regarding Dipute    Anderson, Julie
            Issues of OU-2 ROD                    •   EPA Region IX
                                                               504
12 Aug 93   Base Letter to CRWQCB, CDTSC, and EPA    Baker, Thomas R,
            Regarding Waste Water Disposal           LtCol
                                                     93 CES/CEV
                                                               508
16 Aug 93   EPA Letter to Base Regarding Updated
            Long-Term Groundwater Sampling Plan
                                         Work,  Michael
                                         EPA Region IX
                       533
19 Aug 93   CRWQCB Draft Memo Regarding OU-2
            Dispute Resolution Meeting Minutes, ,10
            Aug 93
                                         Vorster,  Antonia K J  540
                                         California Regional
                                         Water Quality
                                         Control Board
25 Aug 93   EPA Letter to CRWQCB Regarding Draft
            Minutes of OU-2 Meeting, 10 Aug 93
                                         Work,  Michael
                                         EPA Region IX
                       581
27 Aug 93   CRWQCB Letter to HQ ACC, CDHS, and EPA
            Regarding Resolution of OU-2 Dispute
                                         Pearson, J Lawrence
                                         California Regional
                                         Water Quality
                                         Control Board
                      654
Sep 93      Advance Draft Hydrogeological Technical  Jacobs Engineering    668
            Memorandum for OU-2       .               Group, Inc.


01 Sep 93   Base Letter to TRC Members Transmitting  Parker, Scarlette P,  711
            Meeting Agenda                           TSgt
                                                     93 BW/PA
                                      39

-------
                           Castle AFB, CA  - AR DOCUMENTS
                                     Sorted by:
                             Date of  Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
01 Sep 93   EPA Letter to  CRWQCB Regarding EPA
            Comments on Draft Minutes of OU-2
            Meeting, 10 Aug  93, and Draft Waste
            Discharge Requirement, 19 Aug 93
                                         Work, Michael
                                         EPA Region IX
                      738
02 Sep 93   EPA Letter to HQ ACC, CDTSC, and CRWQCB  Takata, Keith
            Regarding Dispute Resolution, ROD for    EPA Region IX
            OU-2
                                                               849
03 Sep 93   HQ ACC Letter  to CDTSC and CRWQCB        Burnet, Gilbert N
            Regarding Dispute Resolution, ROD for    HQ ACC/CEV
            OU-2
                                                               183
08 Sep 93   Base Letter to EPA, CDTSC, and CRWQCB    Fraher, Jeffrey T,    233
            Transmitting RPM Meeting Minutes, 19     Maj
            Aug 93                                   93 BW/CVE


15 Sep 93   Base Letter to Resident Regarding Well   Morris, Brett, Capt   758
            Sampling  Information                     93 BW/CVE


17 Sep 93   Base Letter to EPA, CDTSC, and CRWQCB    Cole, John R, LtCol   824
            Regarding Proposed Agenda  for R^M        93 BW/CVE
            Meeting,  14 Oct  93
20 Sep 93   EPA Letter  to  Base Regarding Revised
            Draft Final ROD for OU-2
                                         Work,  Michael
                                         EPA Region IX
                      831
22 Sep 93   EPA Letter to Base Regarding Delayed
            Draft  Preliminary Conceptual Design
            Document  for OU-2
                                         Work, Michael
                                         EPA Region IX
                      725
22 Sep 93   HQ ACC  Letter to Base Regarding Revised  Battaglia, Michael R   78O
            Draft Final  ROD for  OU-2                 HQ ACC/CEVR
                                      40

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
22 Sep 93   EA Letter to HSC Transmitting Hard Copy  Bugica,  David M
            of Requested Modeling of Groundwater     EA Engineering,
            Flow and Contaminant Dispersion at OU-1  Science, and
                                                     Technology, Inc.
                                                               953
24 Sep 93   HQ ACC Letter to EPA. CDTSC. and CRWQCB  Burnet,  Gilbert N
            Regarding Dispute Resolution, Draft      HQ ACC/CEV
            Final ROD Submission for OU-2
                                                               677
22 Oct 93   EPA Letter to Base Regarding Revised
            Draft Final ROD for OU-2
                                         Work,  Michael
                                         EPA Region IX
                       271
27 Oct 93   CDTSC Letter to Base Regarding Review    Ward,  Daniel T
            Comments on Revised Draft Final ROD for  California
            OU-2, Oct 93                .             Department of Toxic
                                                     Substances Control
                                                               562
Nov 93
Final ROD, OU-2
93 CES/CEVR
                                                                           206
Nov 93      Hydrogeological Technical Memorandum,
            Raw Field Data, OU-2.
                                         Jacobs Engineering
                                         Group, Inc.
                       968
08 Nov 93   EPA Letter to Base Regarding Revised
            Draft Final ROD for OU-2, Nov 93
                                         Work,  Michael
                                         EPA Region IX
                       181
10 Nov 93   Base Letter to EPA, CDTSC, and CRWQCB    Cole,  John R, LtCol   184
            Transmitting Requested Ammended Pages    93 BW/CVE
            of Final ROD for OU-2
12 Nov 93   CDTSC Letter  to Base Regarding Review
            Comments on OU-2 Hydrogeologic
            Technical Memorandum, Oct 93
                                         Ward,  Daniel T
                                         California
                                         Department of Toxic
                                         Substances Control
                       185
15 Nov 93   EPA Letter  to  Base Regarding OU-2 Draft  Work, Michael
            Hydrogeological Technical Memo           EPA Region IX
                                                                 99
                                     41

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
15 Nov 93   Finalized Boring Logs, OU-2  (Revised     Jacobs Engineering     969
            Appendix A)                              Group, Inc.
19 Nov 93   EPA Letter to Base Regarding OU-2 Draft  Work, Michael
            Preliminary Conceptual Design        '    EPA Region IX
                                                                101
23 Nov 93   Final Record of Decision for Operable    AFBCA/OL-I
            Unit-2
                                                               1064
14 Dec 93   Base Letter to CDHS, CRWQCB, and Jacobs  Chan, Arthur D
            Engineering Transmitting Monthly TCE     93 BW/CV
            Results
                                                               1024
Jan 94      Final Hydrogeological Technical
            Memorandum, Vol I of II, OU-2
                                         Jacobs Engineering     975
                                         Group, Inc.
05 Jan 94   Jacobs Engineering Conversation with     Heller, Noah R         932
            CRWQCB Regarding Upper Subshallow HSZ    Jacobs Engineering
            Data Gaps, Off Base OU-2                 Group, Inc.
05 Jan 94   RPM Meeting Minutes,  09 Dec 94
                                         Watkin, Geoff W        951
                                         Jacobs Engineering
                                         Group, Inc.
08 Feb 94   RPM  Meeting  Minutes,  27 Jan  94
                                         Watkin, Geoff W
                                         Jacobs Engineering
                                         Group, Inc.
                       950
Mar 94       Internal Base Memorandum Transmitting
             Proposed Agenda and Draft Charter for
             RAB for Review and Comment
                                         Bishop, Raymond C,
                                         Col
                                         93 BW/CV
                       957
 02 Mar  94    Base Letter to EPA,  CDTSC,  and CRWQCB
             Transmitting RPM Meeting Minutes,  27
             Jan 94
                                         Salgado, Rogelio R
                                         93 BW/CVE
                       926
                                      42

-------
DOC.
DATE
                          Castle AFB, CA  - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
07 Mar 94   Castle AFB Environmental Update
                                         93 BW/PA
                      984
09 Mar 94   Newspaper Article,  "Advisory Board
            Meets"
                                         The Merced Sun Star   985
21 Mar 94   Base Letter  to EPA, CDTSC, and CRWQCB
            Transmitting Final  RPM Meeting Minutes
            from 02 Mar  94 and  Meeting Agenda from
            22 Mar 94
                                         Cole,  John R, LtCol  1029
                                         93 BW/CV
22 Mar 94   SOW, Title  I Services  for Groundwater
            Treatment,  OU-2 and  Title II Services
            for Groundwater Treatment, OU-1
                                         Jacobs Engineering
                                         Group, Inc.
                      947
01 Apr 94   RAB Meeting Minutes,  09 Mar  94
                                         Bishop,  Raymond C,
                                         Col
                                         93 BW/CV
                      1032
19 Apr 94   RPM Meeting  Minutes,  24 Mar  94
                                         Cole, John R, LtCol   954
                                         93 BW/CVE
28 Apr 94   AFBCA Letter to  EPA Transmitting OU-2    Carr, John P
            ROD  Signature Page                      AFBCA/NW
                                                               929
28 Apr 94    EPA  Letter to Base Regarding Interim   •  Roberts, David  E
             Removal Action,  Extraction Well #SE-7    EPA Region  IX
             95%  Design Review,  OU-2
                                                              1035
29 Apr 94    Conceptual  Design Report,  Vol  I of  II,
             OU-2
                                         Jacobs Engineering
                                         Group, Inc.
                       979
29 Apr  94    Conceptual Design Report,  Outline
             Specification,  Vol II of II,  OU-2
                                         Jacobs Engineering
                                         Group, Inc.
                       980
                                      43

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
                                         AUTHOR or
                                         CORP. AUTHOR
FILE
NUMBER
06 May 94   CDTSC- Letter to Base Transmitting
            Comments on Long Term Groundwater
            Sampling Plan, Draft Final Haste
            Management Plan, Draft VLEACH Benzene
            Results, and Specifications for
            Construction of TCE Extraction Well
                                         Austreng,  James C
                                         California
                                         Department of Toxic
                                         Substances Control
1037
09 May 94   Jacobs Engineering Response to EPA
            Comments on Draft Conceptual Design
            Report, Groundwater Treatment, OU-2
                                         Leach,  James D
                                         Jacobs  Engineering
                                         Group,  Inc.
 928
10 May 94   Draft RPM Meeting Minutes, 28 Apr 94
                                         Watkin,  Geoff w
                                         Jacobs Engineering
                                         Group, Inc.
 927
20 May 94   Final RPM Meeting Minutes, 28 Apr 94
            and Meeting Agenda, 26 May 94
                                         Cole,  John R, LtCol  1038
                                         93 BW/CVE
23 May 94   Newspaper Article. "Public
            Notice/Notice of Availability"
                                         The Merced Sun Star  1039
26 May 94   Base Letter to EPA, CDTSC, and CRWQCB    Gaddy, Armon T, Jr,
            Regarding Documentation of Meetings      TSgt             _ .
            with Local Property Owners Impacted by   93 BW/PA
            Environmental Cleanup Efforts
                                                               923
Jun 94      Phase II, Comprehensive Basewide OU
            Risk Assessment. Technical Memorandum
                                         Jacobs Engineering
                                         Group, Inc.
 931
Jun 94      Jacobs Engineering Response to EPA and   Jacobs Engineering
            CRWQCB Comments on Draft Final           Group, Inc.
            Conceptual Design Report, OU-2
                                                               1041
01 Jun 94   Castle AFB Environmental Update
                                         93 BW/PA
 971
                                      44

-------
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
13 Jun 94   Meeting Minutes from AFBCA and ATSDR
            Health Consultations and Data Gap
            Reviews
                                         Stokes, Mark H, Col   1042
                                         AFBCA-AL/OEM
15 Jun 94   RA, Work Plan, OU-2
                                         Jacobs Engineering
                                         Group, Inc.
                       897
17 Jun 94   EPA Letter to Base Concerning Selection  Roberts, David  E
            of Service Center to Administer RD/RA    EPA Region  IX
            Contract for OU-2
                                                                930
03 Aug 94   EPA Letter to Brooks AFB Regarding
            Basic Concerns with SOWs
                                         Roberts,  David E
                                         EPA Region IX
                      1045
25 Aug 94   Summary of Modeling Recommendations anci  Utah State
            Anticipated Actions to be Performed ..    University
            Concerning OU-2
                                                               997
13 Sep 94   RAB Meeting Minutes, 13 Sep 94
                                         93 BW/CV
                      1000
06 Oct 94   Final RPM Meeting Minutes, 22 Sep 94
            and Meeting Agenda, 02 Nov 94
                                         Hicks,  Brad
                                         93 CES/CEVR
                      1006
25 Oct 94   EPA  Letter  to Base Regarding Review of   Roberts, David E
            Preliminary Draft Explanation of       •  EPA Region  IX
            Significance Difference for ROD, OU-2
                                                              1010
27 Oct 94   RAB Meeting Minutes, 13 Sep 94
                                         Mollison, John C,
                                         Jr. Col
                                         93 SPTG/CC
                      1011
11 Nov 94   Long Term Groundwater Sampling Program,  Jacobs Engineering
            Summary of Groundwater Monitoring,       Group, Inc.
            Quarter 3,  94
                                                               1012
                                      45

-------
                          Castle AFB,  CA -  AR DOCUMENTS
                                    Sorted  by:
                            Date of Report:  04/25/96
DOC.
DATE
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
28 Nov 94   Final RPM Meeting Minutes,  02 Nov 94
            and Meeting Agenda,  07 Dec  94
                                         Pohlmeier,  Mark A,    1014
                                         Capt
                                         93  BW/CEV
07 Dec 94   Explanation of Significant Difference
            for the ROD for OU-2
                                        Mollison,  John C.,  •  1063
                                        Col
                                        Roberts,  David E
                                        Ghazi,  Rizgar A
                                        AFBCA/OL-I
                                        EPA  Region IX
                                        California
                                        Department of Toxic
                                        Substances Control
15 Dec 94   CDTSC Letter to Base Regarding Review
            of Draft Comprehensive Basewide RI/FS
            Report
                                        Ghazi,  Rizgar A
                                        California
                                        Department of Toxic
                                        Substances Control
                     1017
15 Mar 95   Meeting Minutes of Remedial Project
            Managers Meeting held on 15 Mar 95
                                         Kumanchik,  Cynthia   1090
                                         Gutierrez-Palmenberg
                                         ,  Inc.
27 Mar 95   Meeting Minutes for 27 Mar 95
            Restoration Advisory Board Meeting
                                         Kumanchik,  Cynthia   1091
                                         Gutierrez-Palmenberg
                                         ,  Inc.
11 Apr 95   Summary of March 1995 Domestic Well
            Sampling Results
                                         McLeod,  Campbell
                                         Jacobs Engineering
                                         Group, Inc.
                     1103
May 95      Environmental Baseline Survey for
            .Twenty-Five Parcels of Land Located
            Near Castle AFB
                                         ACC CES/ESV (Geo
                                         Marine,  Inc.)
                      1069
12 May  95    Draft  Summary of Domestic Well           McLeod, Campbell     1075
             Monitoring January Through April 1995    Jacobs Engineering
                                                     Group, Inc.
                                     46

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
FILE
NUMBER
18 Jul 95   July 18 1995 Remedial Project Managers
            Meeting Minutes
                                         AFBCA/OL-I
                     1112
21 Jul 95   July 1995 Draft Remedial Project
            Managers and Technical Working Group
            Sessions Meeting Minutes
                                         AFBCA/OL-I
                     1114
31 Jul 95   Jacobs Engineering Group, Inc. Stop
            Work Order
                                         Smith,  Alice R.      1118
                                         Jacobs Engineering
                                         Group,  Inc.
24 Aug 95   Assumptions for Revised Design Basis     Hobbins, Christopher 1123
            Report  (RDBR) Groundwater Model          AFCEE/ESB
            Development
12 Sep 95   12 September 1995 Remedial Project
            Managers' Meeting Minutes
                                         AFBCA/OL-I
                     1145
29 Sep 95   12 September 1995 Restoration Advisory   AFBCA/OL-I
            Board Meeting Minutes
                                                              1135
15 Dec 95   21 November 1995 Restoration Advisory    Kumanchik, Cynthia   1151
            Board Meeting Minutes                    Gutierrez-Palmenberg
                                                     ,  Inc.
14 Feb 96   Final January 1996 Remedial Project
            Managers' Meeting Minutes
                                         AFBCA/OL-I
                     1175
19 Feb 96   Data Gap Well Installation for Long
            Term Groundwater Sampling Program
                                         Hobbins,  Christopher 1172
                                         AFCEE/ERB
22 Feb 96   21 February 1996 Draft Remedial Project  Kumanchik, Cynthia   1171
            Managers Meeting Minutes                 Gutierrez-Palmenberg
                                                     ,  Inc.
                                     47

-------
DOC.
DATE
                          Castle AFB, CA - AR DOCUMENTS
                                    Sorted by:
                            Date of Report:  04/25/96
SUBJECT OR TITLE
AUTHOR or
CORP. AUTHOR
PILE
NUMBER
12 Mar 96   CDTSC Geological Services Unit review    Scruggs,  Mary
            of Draft Revised Basis of Design Report  California
            (RBDR)                                   Department of Toxic
                                                     Substances Control
                                                              1167
14 Mar 96   CDTSC's review of Draft Revised Basis
            of Design Report
                                         Ghazi,  Rizgar
                                         California
                                         Department of Toxic
                                         Substances Control
                     1166
15 Mar 96   U.S.EPA comments on Draft Revised Basis  Roberts,  David
            of Design Report (RBDR)                  EPA Region IX
                                                              1165
UNK
Newspaper Article, "Meeting Today on
TCE in Mobile Home Park"
De La Cruz, Mike
The Merced Sun Star
                                                                            47
UNK
Phase II, SOW, Construct Water Line
Located at Wallace Road and Nearby
Hospital Road
                                                     UNK
                      906
                                     48

-------
Tables

-------
                                    TABLE 2-1
                         SELECTED REMEDIAL ACTIONS
Plume
Main Base Plume
East Base Plume .
Castle Vista Plume
North Base Plume
Landfill 1 Plume
Landfill 4 Plume
Selected Remedial Action
Plume capture and treatment to achieve groundwater cleanup to the MCL
level. Extraction of contaminated groundwater; treatment using a
combination of air stripping and carbon adsorption; disposal of treated
groundwater using reinjection, canal discharge, and/or reuse. Remedial
action to be implemented in a phased approach.*
Impacted area well destruction and monitoring utilizing the sealing and
abandonment of wells to protect against further cross contamination of
HSZs, and monitoring to develop more complete definition of the
contamination. If further active remediation is needed, a pump and treat
approach will be implemented as the presumptive remedy.*
Implementation of active pump and treat as a presumptive remedy. The
remedy consists of plume capture and treatment to achieve groundwater
cleanup to the MCL level; extraction of contaminated groundwater;
treatment using a combination of air stripping and carbon adsorption; and
disposal of treated groundwater using reinjection, canal discharge, and/or
reuse. Remedial action to be implemented in a phased approach.*
No further active remediation"
No further active remediation"
No further active remediation"
* Administrative controls, in addition to the indicated remedy, will be implemented as necessary.

** Active remediation of the North Base, Landfill 4, and Landfill 1 Plume Regions is not
warranted because action is being taken to remediate the sources, and because removing the low-
concentration contaminants from the groundwater would provide little benefit while incurring
high costs. However, because several of the contaminants are above the primary drinking water
standards, institutional controls (such as deed restrictions) will be applied to prohibit the
installation of groundwater supply wells on Castle AE3 that would jeopardize public health or
the environment from North Base, Landfill 4 and Landfill 1 Plume areas. Additionally, long-
term monitoring will be continued and modified as necessary to monitor contaminant
concentrations. Contamination concentration levels in the groundwater will be monitored as part
of the LTGSP and will be reevaluated annually.

-------
                                        TABLE 3-1
   GROUNDWATER ZONES AND PLUME REGIONS AT CASTLE AFB, CA

Plume/Region
Main Base
Plume 1
Main Base
Plume 2
Landfill 4
Plume
North Base
Plume
East Base
Plume
Landfill 1
Plume
Castle Vista
Plume
Location
Beneath the Main Base sector,
corresponding to the OU-1
remediation area (installed treatment
system)
Beneath the Main Base sector,
corresponding to the OU-2
remediation area (treatment system
under construction)
Beneath Landfill 4 in the West Base
sector
Beneath Landfill 5 in the North Base
sector
Beneath the East Base sector
Beneath Landfill 1 in the South Base
sector
Beneath the Castle Vista Landfill B in
the off-base sector
Principal
Contaminant(s)
TCE1 and other
VOCs
TCE and other
VOCs
VOCs
TCE and other
VOCs
TCE and other
VOCs
VOCs and
arsenic2
VOCs
Zones9 of
Contamination
shallow, upper
subshallow, lower
subshallow, and
confined
shallow, upper
subshallow. lower
subshallow, and
confined
shallow
shallow
shallow
shallow and upper
subshallow
shallow
1   Tricholorethylene (TCE) is a volatile organic compound (VOQ however, since TCE is the major gnundwater contaminant at
   Castle Airport, it is identified separately from the VOC grouping.
2   A naturally occurring chemical with elevated levels common in the region's groundwater.
3   The depth of groundwaier zones at Castle Airport are as follows: Shallow - 60 to 95 feel below ground surface (bgs); Upper
   Subshallow - 96 to 160 feet bgs: Lower Subshallow - 161 to 220 feet bgs; Confined • 220 to 350 feet bgs; Deep - 351 feel bgs.

-------
                                                                                       Table 3-2 a
                                                  Volume and Contaminant Mass Estimate for Groundwater Plumes Containing TCE
                                                                   'CE'-l/Uw and TC&&mwnln*tM; fliwrnrtwrttr Volum*-^
            LF4(pluma«1)
1.659
0.0

                                                                        2,943
                                                                                682.057.000
                                                                          0.0
                                                      10,308,000
                                                                                                (Ib)
                                                                       1.130
                                                     0.4
                                                               1.937
                                                    0.7
                                                                                                                    .T«tatlu«*
                                                              3.066
                                                            614.337.000
                                                     1.1
                                                                        1.096
                                                                          0.0
                                                       1.879
                                                         0.0
                                                                                                                    2.974
                                                                                                                                                                                   0.0
            LF4 (plume §2)
                                                0.0
                                                             0.0
                                               0.0
                                   3,500,000
                                                                                                    0.2
                                                                                                                0.3
                                                                0.4
                                                                                  0.0
                                                                                                                                                                       0.0
                                                                                                                                                        0.0
            NBP
                               420,000
                     0.1
                                                                          0.3
                                  14,000,000
                                                                                                    3.2
                                                    5.6
                                                                                                                            8.8
                                                              7.000.000
                                                                                                                               1.3
                                                                                       2.3
                                                                                                                                                        3.6
                                                                                                                                                        3.B
                                                                                                                                                        0.0
            EBP (»1)
                              3.360.000
                                                0.4
                                                             0.7
                                                                          1.1
                                  21.070.000
                                                                                                    2.0
                                                                                                                3.4
                                                                                                                             5.4
                                                                         5,600,000
                                                                                                                                                          1.4
                                                                                               2.4
            EBP (12)
                                                0.0
                                                             0.0
                                                                          0.0
                                   1J15.000
                                                                                                                0.3
                                                                                                                            0.4
                                                                                              0.0
                                                                                               0.0
            EBP(t3)
                             23.100.000
                      24l
              41
              64
         45.635,000
                     41
   70
                                                               111
                                                                         26.600.000
                                                                                                           27
                                                                                                                        47
                                                                                                                        74
                                                                                                                       O.C
                                                                                                                       0.0
            LF1
                                                0.0
                                  0.0
                          0.0
          1,260,000
                    0.1
  0.1
                                                               0.1
                                                                                                                                                          0.0
                                                                                                                                                                       0.0
           CVLF
                                                0.0
                                  0.0
                          0.0
          5.040,000
                    0.3
  0.5
                                                                                                                            0.9
                                                                                                                                                          0.0
                                                                                                                                                                       0.0
USS
            MP
                           308.946.000
                                1.083
                        1.779
                   458.190.000
                                                                                                   713
                                      1,109
                                           1,821
                      351.000.000
                                                                                            703
                                                                                                                                                                     1.094
                                                                                                                      1,797
LSS
            MP
213348.000
.393
674
1.067
470.764.000
                                                                                                   418
                                                                                                               714
             1,130
                                                                      308310.000
                                                                                                                                                         398
                                                                                                          683
                                                                                                                      V081
           MP
                           11S.1SO.OOO
                                                60
                                                            137
                                                                         217
                                                    353,675,000
                                                                                                               290
                                                                            459
                                                                       190.7SO.OOO
                                                                                                                                                          99
                                                                                                                       170
                                                                                                                                                                                  269
MBPToUl
                          1.069.096.000
                   2353
           3,763
           6,006
       1.864.666,000
                  2.428
4.049
                                                             6,477
                                                                       1.364397.000
 2396
3,825
6,121
3r«nd Total
                          1.085.976.000
                   2377
           3.794
           6.071
      2.087.114.000
                  2.47S
4.130
                                                             6,605
                                                                       1.403.497.000
_2.326
3J76
6302
ABBRttftATTOMS
HSZ        hydfo*lr*flgr*phJo zone
LMan      IquUimM
SUUi      (oRdmut
TCE
COV
cud        euUofMl
Ib          pound*
USS
LSS
MP
EBP
LF4
NBP
tFI
CVLF
           mleragnniiptrllMr
           upp*r*utahdow
           tower (Ubdulow
           MttoPlum*
           E«IB*MPIunM
           UfldlUi4
           North BtM Plum*
           Undffll
           C**«*VbtaUndlII
                                                                A98UMPTIOM9

                                                                Ou* to founding of numb*™, th« loUl mMM* miy not add up
                                                                TOO                     total OT)«nloe»rt>on-0.2%
                                                                KM                     orginte eaitaon partition oo*flld*nt> 125 mVg
                                                                SpwHIe gnvrty             2.65
                                                                WHwdwnNy               82.4lVcufi

                                                                TMekn*** o> wttw bearing ion* In uch HSZ
                                                                •hallow                   (SSIoHS-bgtlorSffthleknM*
                                                                uppwiutahallow            (IIS to 167 bgi) or 451 IMoknM*
                                                                towet .ub»hillow            (t60loZ4?ba*)or8S>tMekn***
                                                                oonflMd                  (245 lo 379 bg*) or 12F ttilekM**
                                                                Porotity ol walcr bearing zone
                                                                •haflow
                                                                upper •ubihallow
                                                                tower lubthallow
                                                                                                                           0.26
                                                                                                                            0.3
                                                                                                                           0.28
                                                                                                                           0.28
                                                                                      Pig* I Of I

-------
                                                                         Table 3-2 b
  Volume and Contaminant Mass Estimate for Groundwater Plumes of Organic Compounds Identified In the Remedial Investigation (other than TCE)
                                                         .ContamlnentAlMsearifndiGroundwateriiVolumeaj1-
 Shallow
                      NBP
                      CVLF
                                Chloroform
                                Cls-1 ,2-DlchloroethYlene
                                PCE
              PCE
                               Bis g-Ethylhexyl) Phttialate
              PCE
                               Cls-1 .2-Dlchtoroethylene
                                          2,340,000
                                          6.120.000
                                          8.460,000
                              225.000
                                           450.000
                              540.000
                                           990.000
                                                    1.54
                                                    4.60
                                                    4.40
                       3.10
                                                   54.00
                                                                                   3.00
                                                    3.00
                                       32.760.000
                                       85.680.000
                                       118.440.000
                 3,150,000
                                        6.300,000
                                        7,560.000
                                       13.860,000
                                   25
                                   33
                                   21
                                 24
                                                 28
                              57
 Jpper SubshaUow
     MP
PCE
 765.000
2.60
 10,327.500
 Confined
     MP
Benzene
9.720,000
0.70
340,200.000
15
                                                                 17
 ABBREVIATIONS
 HSZ
 LMass
 SMass
 TCE
 CQV
 cuft
 Ib
 Ptf
 USS
 LSS
hydrostraUgraphlc zone
liquid mass
solid mass
trichloroethene
contaminated groundwater volume
cubic feet
pounds
mlcrograms per liter
upper subahallow
lower subshallow
                                         MP
                                         EBP
                                         LF4
                                         NBP
                                         LF1
                                         CVLF
                                     Main Plume
                                     East Base Plume
                                     Landfill 4
                                     North Base Plume
                                     Landfill 1
                                     Castle Vista Landfill
                                            Calculation of the solid mass of
                                            bls(2-ethvthexyl) phthalate based
                                            on the published Koc and average
                                            contaminant level would yield a
                                            solid mass In excess of 80,000,000
                                            pounds. Since no procedure for
                                            calculating a reasonable estimate
                                            of solid mass Is available, none
                                            was calculated.
ASSUMPTIONS
TOC              total organic carbon •
Soil Specific gravity 2.65    •
Water density      62.4lb/cuft
                  02%
Thickness of water bearing zone In each HSZ:
shallow            (65 to 115' bgs) or 50* thickness
upper subshallow   (115 to 1W bgs) or 45' thickness
lower subshallow    (160 to 245' bgs) or 85' thickness
confined           (245 to 370'bgs) or 1251 thickness
                                         Porosity of water bearing zone:
                                         shallow                            0.28
                                         upper subshallow                     0.3
                                         lower subshallow                    0.28
                                         confined                           0.28

                                         Organic Carbon Partition Coefficient (Koc):
                                         Carbon Tetrachlortde                  439
                                         Chloroform                           44
                                         C/s-1,2-dichloroethylene                65
                                         Bis (2-ethylhexyl) phthalate       2.00E+09
                                         PCE                              364.0
                                         Benzene           ,                 65

-------
                                                               Table 3-3
                    Summary of COCs and PRAOs for Groundwater Contaminant Plumes
Main Plume

Shallow
Hydrostratigraphlc
Zone (HSZ)

Plume Is characterized by TCE and contains other HVOs and AVOs in excess of
regulatory and risk standards. Plume extends off-Base, and pinches out to the south
and west of the base. The areal extent of the TCE plume is approximately 1,000 acres.
The highest concentration of TCE recently detected was 740 pg/L  DBCP Is present
Inside and outside the TCE plume exceeding regulatory and risk criteria.  Benzene is
present in one well, JM11, at 780 ug/L.
Extent of the TCE plume adequately characterizes
organic contaminants except for OBCP.

DBCP forms a distinct plume (approximately 6,800
feet long), primarily to the west of the Base, which is
likely caused by agricultural sources. There appear
to be multiple on-Base sources for the TCE and other
organics that are present in the plume. Plume
location and extent appear to have been relatively
stable since 1990. This is possibly because of a
pinch-out of the predominant water-bearing section.

The COCs identified for the Main Plume Regions are
benzene, carbon tetrachlorlde, chloroform, c/s-1,2,-
dichloroethene, TCE, and PCE. DBCP is excluded
because it is considered to be an agricultural
contaminant. These COCs are applicable to all the
Main Base Plume Region HSZs discussed later in
this Table, and PRAOs have been developed.
 lain Plume
Upper Subshallow
HSZ
Plume Is smaller (approximately 330 acres) but the TCE concentration still exceeds
regulatory and risk screening levels. The highest TCE concentration detected was 160
ug/L at well MW-904. PCE'was detected at concentrations exceeding regulatory and
risk screening levels In wells located within the plume and Base boundaries. The TCE
plume boundary extends off-Base. A DBCP plume is present west of CAFB, beneath
tn agricultural area, at levels exceeding regulatory and risk screening values.
Ethylene dibromlde (a pesticide) Is also detected within the DBCP plume.
The TCE plume adequately characterizes organic
contaminants except for DBCP.  DBCP forms a plume
west of CAFB approximately 6,000 feet long In this
HSZ that commingles with the main TCE plume.  The
DBCP source Is present off-Base at concentrations
exceeding risk standards.
Main Plume

Lower Subshallow
HSZ
The plume decreases to approximately 300 acres in size. It corresponds to the
southern portion of the Main Plume. TCE concentrations exceed regulatory levels and
the plume boundary extends off-Base. The highest TCE concentration detected was
190 ug/L at well MW-863.  PCE concentrations (exceeding regulatory and risk
screening levels) were detected in one well, MW608 outside the boundaries of the TCE
plume. The boundary of the plume Is still Influenced by the pinch-out of the coarse
jraJned sediments south and west of the Base. Analytical data are limited due to the
ack of wells Installed In this HSZ. DBCP was not detected.	
Available analytical data indicates that the TCE
plume adequately characterizes reported organic
contaminants. The plume has decreased in size but
the configuration still appears to be influenced by the
trend of the fine-grained sediments to the southwest.
DBCP has not migrated to this HSZ.
                                                               Page 1 of 3

-------
                                                        Table 3-3 (Continued)
 S
 Main Plume

 Confined HSZ
The TCE plume size and concentration are less than in the overlying HSZ; however,
the plume still extends off-Base. The extent of the plume is over 230 acres, with 29
ug/L (at MW-927) the highest concentration of TCE detected. The plume configuration
is north to south, consistent with the trend of the primary pathway, the North Merced
Gravel. The North Merced Gravel Is an important groundwater source for irrigation and
domestic wells. Benzene, at a maximum of 1.6 ug/L, was detected in nine wells, six
being outside the TCE plume.  C/S-1.2-DCE was also detected above MCL values at
the TCE plume boundary. Other than TCE, no organic compound was identified by risk
screening.	
Available analytical data suggest the TCE plume
sufficiently characterizes the extent of contaminants.
TCE has impacted groundwater to a depth that
includes an important local groundwater source. TCE
has not been detected in the underlying deep HSZ
well (MW-832). Due to limited analytical data, plume
migration trends cannot be evaluated.
Landfill 4 Plume #1
Shallow HSZ
TCE concentrations detected did not exceed 1.1 ug/L (below regulatory and risk
screening criteria). Detected organic compounds were within the TCE plume which
covers approximately 17 acres. DEHP, DBCP, and PCE were detected at levels
exceeding MCLs or human health risk screening criteria.
The extent of the TCE plume sufficiently
characterizes detected organic compounds.  The
TCE plume concentrations do not exceed MCL, PRG
or risk screening values. There are no COCs
identified for the Landfill 4 Plume. No PRAOs were
identified.
Landfill 4 Plume #2

Shallow HSZ
The concentration of 0.75 ug/L TCE in well MW-846 defines this plume of
approximately 5.7 acres. DEHP was the only compound detected in this well above
regulatory guidelines. DBCP (identified by the risk assessment (RAJ) was detected in
nearby well MW-842).
DBCP forms a plume to the southwest, the plume is
considered to be the result of DBCP being an
agricultural contaminant.

See conclusion section above for Landfill 4 Plume #1
for COCs.
North Base Plume

Shallow HSZ
TCE was detected in three wells at concentrations not exceeding the MCL. Other
organic compounds (including 1.4-dichlorobenzene, methelyne chloride, and PCE)
were detected at levels exceeding regulatory and risk criteria in several wells within the
 wrimeter of the plume. The lateral extent of the plume Is approximately 23 acres.
 3EHP was reported in several wells outside the TCE plume and In the nearby
background wells. A small plume of DEHP Is located southeast of the TCE plume.
The extent of the TCE plume adequately
characterizes the extent of suspected organic
contaminants exceeding risk values with the
exception of DEHP. COCs include DEHP, TCE and
PCE. All COC plumes had limited extent and mass.
There are no PRAOs and no action Is recommended.
East Base Plume #1

Shallow HSZ
TCE concentrations of 5.5 ug/L, detected in well MW-849 (located off-Base), identify
the plume which extends over approximately 35 acres. Organic compounds (including
carbon tetrachloride and PCE) which exceeded risk values were detected in wells
ocated within the perimeter of this plume.
The extent of the TCE plume adequately
characterizes the extent of contaminants. The plume
extends off-Base. The COC for the East Base
 lumes Region is TCE. PRAOs have been
developed.	      	
East Base Plume #2

Shallow HSZ
TCE concentrations of 5.3 and 1.4 ug/L in wells MW-330 and MW-886, respectively,
 dentify the plume (approximately 9 acres). No other organic or inorganic compounds
were detected In wells at levels exceeding MCLs.	
The TCE plume boundaries effectively characterize
the extent of contaminants. See conclusions for East
Base Plume #1 Shallow HSZ for COCs.
                                                                PageJ? of 3

-------
                                                        Table 3-3 (Continued)
East Base Plume #3

Shallow HSZ
Concentrations of TCE (19 and 45 ug/L) detected during the first sampling round at
wells MW-883 and MW-884, respectively, identify the plume. The approximate extent
of the plume is 68 acres. PCE and chloroform were detected in wells MW-872 and
MW-858 near the upgradient boundary of the plume at concentrations exceeding
regulatory criteria.  PCE and TCE concentrations also exceeded risk based values.
Available analytical data suggest a TCE plume with
elevated levels of PCE detected at its upgradient
perimeter. See conclusions for East Base Plume #1
for COCs and PRAOs.
Landfill 1 Plume

Shallow HSZ
TCE concentrations of 0.60 ug/L in well MW-542 identifies the presence of this 2 acre
plume. Concentrations of chloroform above regulatory levels were reported outside the
plume perimeter in several wells; however, chloroform was also reported in several
sample blanks.	
TCE is the COC for Landfill 1 Plume.  No PRAOs
were developed and no action is recommended.
Castle Vista Landfill
Plume
Shallow HSZ
TCE concentrations of 1.4 ug/L In well MW-003 identify the plume located at Landfill B.
The plume's lateral extent is estimated to be over 18 acres. Other organic compounds
(PCE, C/S-1.2-DCE, and 1,2-dibromoethane [EDB], a pesticide commonly detected in
groundwater throughout the San Joaquin valley) were detected in well MW-003 at
levels exceeding either MCLs or risk screening values. TCE concentrations do not
exceed regulatory or risk levels. This plume is located in the agricultural area
downgradient of the Base. Elevated levels of metals were reported in well MW-006
located In Landfill-B.	   	
PCE and cis-1,2-DCE are COCs. All COC plumes
identified had limited extent and mass. There were
no PRAOs and no action is recommended In the
RI/FS.  Based on additional ppst-RI/FS data, a pump
and treat remedial action has been selected..
 LEGEND:
 1,2-DCPA      1,2-dichloropropane
 AVO           Aromatic volatile organics
 DEHP         bis-2-ethyl hexylphlate
 c/s-1,2-DCE    cis-1,2dichloroethene
 OBCP         Dibromo-3-chloropropane
 HSZ           Hydrostratigraphlc zone
 HVO           Halogenated volatile organics
                                                    MCL           Maximum contaminant level
                                                    PCE           Tetrachloroethene
                                                    PRAO         Preliminary Remedial Action Objectives
                                                    RAGS         Risk Assessment Guidance for Superfund
                                                    TCE           Trichloroethene
                                                    VC            Vinyl chloride
                                                                Page 3 of 3

-------
                                              TABLE 3-4
                               RISK ASSESSMENT SUMMARY
Table 3-4. Risk Assessment Summar
Plume
Region
Main
Plume 1
Main
Plume 2
East Base
Castle
Vista
North Base
Landfill 1
Landfill 4
Groundwater
Shallow
Upper
Subshallow
Lower
L .Subshallow
Confined
Shallow
Upper
Subshallow
Lower
Subshallow
Confined
Shallow
Shallow
Shallow
Shallow
Shallow
Principal
Contaminants'
TCE
HCBD
1.1 DCE
TCE
cis 1,2 DCE
TCE
TCE
TCE
TCE
DEHP
TCE
Benzene
TCE
DEHP
PCE
DEHP
PCE
DEHP
Antimony
Exposure Point
Concentra-
tion Cne/L)2
91
0.66
0.73
156
0.91
17.4
33.6
105
208
15
4
0.5
2.25
37
11
37
0.56
39
i
Standard
(ug/L)J
5
6
5
5
5
5
5
4
5
1
5
4
5
4
5
4
Cancer
Risk4
9.0xlO'5
2.2x10^
1.9xlO's
2.6x10*
1.9x10-"
l.SxlO-4
2.9x10^
3-OxlO-6
8.7X10'5
1.1x10-"
S.2xl05
2.9x10-*
1.7x10"*
Hazard
Index4
2.7
4.1
0.6
3.9
2.9
3.2
0.08
0.05
0.6
0.3
0.4
1.8
3.7
Contaminants lilted «re the principal contributor! to the total cancer risk and/or hazard index
F.xptmice point concentration is the concentration of the contaminant at the point of human exposure, a* analyzed in the Risk
Assessment
Standards are the more restrictive of federal or California standards for safe drinking water.
The ftaiKTr risk and hazard index are the total risk/hazard for aU contributions under the adult
leads to the highest value
                                                                                        exposure scenario that
ug/L      Micrograna of contaminant per liter of water
TCE      Trichloroetbyiene
PCE      Perchloroethyiene
                                                    DCE     Dichlorocthene
                                                    DEHP    Bis-(3-elhyu>eicyl)pbthalate
                                                    HCBD   Hexachlorobutadtene

-------
                            Table 3-5
Chemicals of Potential Concern (COPCs) in Groundwater by Plume Region
Detected Chemical
ORGANICS
1,1-Dlchtoroethene
1 .2-Dibromo-3-chloropropane (OBCP)
1,2-Dlbromoethane (ethylene dibromlde)
1 ,2-Dlchlorobenzene
,3-Dlchlorobenzene
1.4-Dlchforobenzene
,1-OlcWoroe thane
1,2-Dlchloroethane
1,2-Dtehloroethene
1.2-Dlcnloroprepane
.2.3-Trichlorobenzene
142,4-Trtchlorobenzene
1.1.1 -Trtchloroethane
.2.4-Trlmethvlbenzene
1.3.5-Trimethylbenzene (mesltvlene)
l-Chtorotoluene
Benzene
>l8(2ethylhexvl)Dhthalate
Bromodlchloromethane
Bromoform
Carbon Tetrachlortde
Chlorobenzene
JhtorofOfTn
Hs-1.2-Dlchloroflthene
Dlbromochloromethane
Dlchlorodlfluoromethane
Ethylbenzene
HexacMorobutadlene
Isooroovtbenzene
Methytena Chloride
laphthalene
i-Butylbenzene
hPropylbenzene
p-lsopropvttoluene
t-Butylbenzene
Fetrachloroethene
Main Plume
Region 1
(shallow
HSZ)

•



•
•
•
•



•

• *
•
•
•



•















Main Plume
Region 1
(upper sub*
shallow HSZ)


•


















•

•
•











•
Main Plume
Region 1
(lower sub*
shallow HSZ)










•



•


•



•

•
•

•
•

•



•
•
•
•
Main Plume
Region 1
(confined
HSZ)













•
•
•

•



•
•

•


•

•



•

•
•
Main Plume
Region 2
S U L CF


•
•
•





•
•
•

•








•
•

•



•





•


•
•
•












•
•




•






•




























































•




•




•

•
•


•



Castle Vista
Plume
Region



•













•





•
•











•
East Base
Plume
Region











•

•
•


•
•


•



•




•





•
Landfill 1
PJume
Region
(shallow
HSZ)























•


•









•
Landfill 1
Plume
Region
(upper sub-
shallow
HSZ)























•













Landfill 4
Plume
Region


•








•
•

•


•
•

•










•

•


•
North
Base
Plume
Region






•
e



•





e
•




•
•

•


•
•





•
                           Page 1 of 2

-------
                                                         Table 3-5
                          Chemicals of Potential Concern (COPCs) in Groundwater by Plume Region
Detected Chemical
Toluene
rrichloroethene
Trfchlorofluromelhane
Vinyl chloride
Xylenes
NORGANICS
Aluminum
Antimony
Arsenic
Barium
Boron
Chromium
Cobalt
Lead
Molybendum
Nickel
Silica
Silver
'anadium
Main Plume
Region 1
(shallow
HSZ)
•
•
•

•

•




•
•

•

•

•
Main Plume
Region 1
(upper tub-
shallow HSZ)
•
•


•













•
Main Plume
Region 1
(lower sub-
shallow HSZ)
•
•


•

•


•

•
•
•


•

•
Main Plume
Region 1
(confined
HSZ)
•
•


•

•

•
•

•
•



•

•
Main Plume
Region 2
S U L CF
•
•


•






•


•
•
•


•
•









•


•
•
•



•

















•



•














Castle Vista
Plume
Region
•
•

















East Base
Plume •
Region
•
•
•

•



•


•


•
•

•

Landfill 1
. ' Plume
Region
(shallow
HSZ)

•






•

•
•


.
•
•

•
Landfill 1
Plume
Region
(upper sub-
shallow
HSZ)

•







•
•








Landfill 4
Plume
Region
•
•


•

•
•
•


•
•



•

•
North
Base
Plume
Region
•
•
•
•
•







•


•
•


S«shallow HSZ
U»upper subshallow HSZ
Utower subshallow HSZ
OconflnedHSZ

-------
                 Table 3-6
Groundwater Exposure Pathways Matrix for CAFB

Exposure Route
Ingestion
Dermal Contact
(Showering)
Inhalation of
Volatiles
Ingestion of
Homegrown
Produce
Residential
Adult
X
X
X
X
Child
X
X
X
X
Industrial
Adult
X
X


                  Page 1 of 1

-------
                                                                      TABLE 3-7
Toxicity Criteria for Contaminants of Potential Concern: Carcinogenicity
Chemical
Welght-
of-
Evidence
SF. ,.
(mg/kg-day)
Reference
SF,
(mg/kg-day)'1
Reference
Target
Inorganics
Arsenic
Lead
A
B2
1.5E+00
NO
IRIS
IRIS
-1.5E+01
NO
IRIS
IRIS
human: skin, lungs
rat, mouse: kidney
Organics
Benzene
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromoform
Carbon tetrachloride
Chloroform
1,2,-Dlbromo-3-dichloropropane
Dibromochloromethane
t,2-Dlbromoethane
1 ,4-Dlchlorobenzene
1,1-Dichloroethane
1,2-Dichloroethane
1,1-Dlchloroethene
1 ,2-Dlchloropropane
Hexachlorobutadiene
Methylene chloride
Tetrachloroethene
Trichloroethene
Vinyl chloride
A
B2
82
B2
B2
B2
B2
C
B2
B2
C
B2
C
B2
C
B2
•«
B2/C
-
1.0E-01
1.4E-02
1.3E-01
7.9E-03
1.3E-01
6.1E-03
1.4E+00
8.4E-02
8.5E+01
4.0E-02
5.7E-03
9.1E-02
6.0E-01
6.8E-02
7.8E-02
1.4E-02
5.1E-02
1.5E-02
1.9E+00
Cal/EPA
IRIS
Cal/EPA
IRIS
IRIS
IRIS
HEAST
IRIS
IRIS
Cal/EPA
Cal/EPA
IRIS
IRIS
HEAST
IRIS
Cal/EPA
Cal/EPA
Cal/EPA
HEAST
1.0E-01
1.4E-02(R)
1.3E-01
3.9E-03
5.3E-02
8.0E-02
2.4E-03
8.4E-02(R)
7.7E-01
4.0E-02
5.7E-03
9.1E-02
1.8E-01
6.8E-02(R)
7.8E-02
3.5E-03
2.1E-02
1.0E-02
3.0E-01
Cal/EPA
IRIS
Cal/EPA
HEAST
IRIS
IRIS
HEAST
IRIS
IRIS
Cal/EPA
Cal/EPA
IRIS
IRIS
HEAST
HEAST
Cal/EPA
Cal/EPA
Cal/EPA
HEAST
human: leukemia, lymphomas
rat: liver
rat, mouse: liver, kidney
rat: liver
rat: liver
rat: liver, kidney
rat, mouse: stomach, liver, kidney
mouse: liver
rat: stomach, nasal cavity
mouse: liver
rat, mouse: liver, mammary
rat: lung, stomach, circulatory system
mouse: kidney
mouse: liver
rat: kidney
rat, mouse: liver, lung
rat, mouse: fiver, leukemia
rat:, mouse: liver, lung
rat: liver, lung
NO B No data are available
- 9 Indicated that the chemical Is not located In the references
Toxicity criteria developed by ECAO were obtained from EPA Region IX
R = indicates that the value for the Inhalation pathway was extrapolated from the oral SF/RID
                                                                 loM

-------
TABLE 3-8
Toxicity Criteria for Contaminants of Potential Concern: Chronic Toxlclty
Chemical
RfD0
mg/kg-day
UF
Reference
RfD,
mg/kg-day
UF
Reference
Target and Critical Effect
Inorganics
Aluminum
Antimony
Arsenic
Barium
Boron
Chromium
Cobalt
Lead
Molybdenum
Nickel
Selenium
Silica
Silver
Vanadium
1.0E+00
4.0E-04
3.0E-04
7.0E-02
9.0E-02
1.0E+00
6.0E-02
ND
5.0E-03 .
2.0E-02
5.0E-03

5.0E-03
7.0E-03

1000
3
3
100
100


30
300
3

3
100
ECAO
IRIS
IRIS
IRIS
IRIS
IRIS
ECAO
IRIS
IRIS
IRIS
IRIS

IRIS
HEAST


NO

5.7E-03

2.9E-04
ND

ND




















IRIS



ECAO
IRIS

IRIS





rat: blood glucose
human: hyperpigmentaion, vascular complications
human: increased blood pressure
dog: testlcular atrophy, human: bronchial irritation
rat: no effect


human: increased uric acid levels
rat: decreased organ weights
human: selenosis

human: argyrla

Organlcs
Benzene
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromoform
/?-Butylbenzene
/•Butylbenzene
Carbon tetrachloride
Chlorobenzene
Chloroform
2-Chlorotoluene
1 ,2-Dlbromo-3-chloropropane
Dibromochloromethane
1,2-Dibromoethane
1,2-Dlchlorobenzene
1,3-Dlchlorobenzene
1.4-Dlchlorobenzene
Dichlorodifluoromethane .
1.1-Dlchloroethane
1,2-Dlchloroethane
1.7E-03(R)
2.0E-02
2.0E-02
2.0E-02
-
~
7.0E-04
2.0E-02
1.0E-02
2.0E-02
5.7E-05(R)
2.0E-02
5.7E-02(R)
9.0E-02
-
2.3E-OKR)
2.0E-01
1.0E-01
NO

1000
1000
1000


1000
1000
1000
1000

1000

1000


100
1000

IRIS
IRIS
IRIS
IRIS


IRIS
IRIS
IRIS
IRIS

IRIS

IRIS

IRIS
IRIS
HEAST
IRIS
1.7E-03
2.0E-02(R)
2.0E-02JR)
2.0E-02(R)
-
-
5.7E-04
5.7E-03
1.0E-02(R)
2.0E-02(R)
5.7E-05
2.0E-02(R)
5.7E-02
9.0E-02(R)
-
2.3E-01
5.7E-02
1.4E-01
ND










1000

1000


100
10000
1000

ECAO
IRIS
IRIS
IRIS


ECAO
ECAO
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS

IRIS
HEAST
HEAST
IRIS

guinea pig: Increased liver weight
mouse: renal cytomegaly
rat: hepatic lesions


rat: liver lesions
dog: histopathologjcal liver and kidney effects
dog: fatty cyst formation in liver
rat: decreased whole body weight gain
rabbit: testicular effects
rat: reduced whole body weight gain, liver lesions
human: spermatic effects
rat: no observed effects

rat: Increased liver weights
rat: reduced body weight
rat: no observed effects

      1of3

-------
TABLE 3-8 (continued)
Toxlclty Criteria for Contaminants of Potentential Concern: Chronic Toxicity
Chemical
RfD.
mg/kg-day
UF
Reference
RfD,
mg/kg-day
UF
Reference
Target and Critical Effect
Inorganics
Aluminum
Antimony
Arsenic
Barium
Boron
Chromium
Cobalt
Lead
Molybdenum
Nickel
Selenium
Silica
Silver
Vanadium
1.0E+00
4.0E-04
3.0E-04
7.0E-02
9.0E-02
1.0E+00
6.0E-02
ND
5.0E-03
2.0E-02
5.0E-03

5.0E-03
7.0E-03

1000
3
3
100
100


30
300
3

3
100
ECAO
IRIS
IRIS
IRIS
IRIS
IRIS
ECAO
IRIS
IRIS
IRIS
IRIS

IRIS
HEAST


ND

5.7E-03

2.9E-04
ND

ND -




















IRIS



ECAO
IRIS

IRIS





rat: blood glucose
human: hyperkpigmentaion, vascular complications
human: increased blood pressure
dog: testicular atrophy, human: bronchial irritation
rat: no effect


human: increased uric acid levels
rat: decreased organ wieghts
human: selenosis

human: argyria.

Organics *
Benzene
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromoform
n-Butylbenzene
/-Butylbenzene
Carbon tetrachloride
Chlorobenzene
Chloroform
2-Chlorotoluene
1 ,2-Dibromo-3-chloropropane
Dibromochloromethane
1 ,2-Oibromoethane
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
1.7E-03(R)
2.0E-02
2.0E-02
2.0E-02
*•
••
7.0E-04
2.0E-02
1.0E-02
2.0E-02
5.7E-05(R)
2.0E-02
5.7E-02(R)
9.0E-02
•*
2.3E-01(R)

1000
1000
1000


1000
1000
1000
1000

1000

1000


IRIS
IRIS
IRIS
IRIS


IRIS
IRIS
IRIS
IRIS

IRIS

IRIS

IRIS
1.7E-03
2.0E-02(R)
2.0E-02(R)
2.0E-02(R)
••
-
5.7E-04
5.7E-03
1.0E-02(R)
2.0E-02(R)
5.7E-05
2.0E-02(R)
5.7E-02
9.0E-02(R)
«
2.3E-01










1000

1000


100
ECAO
IRIS
IRIS
IRIS


ECAO
ECAO
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS

IRIS

guinea pig: increased liver weight
mouse: renal cytomegaly
rat: hepatic lesions


rat: liver lesions
dog: histopathological liver and kidney effects
dog: fatty cyst formation in liver
rat: decreased whole body weight gain
rabbit: testicular effects
rat: reduced whole body weight gain, liver lesions
human: spermatic effects
rat: no observed effects

rat: increased liver weights
           2 of 3

-------
                                                                   TABLE 3-8 (continued)
Toxicity Criteria for Contaminants of Potentential Concern: Chronic Toxlcity
Chemical
Dichlorodifluoromethane
1,1-Dichloroethane
1 ,2-Dichloroethane
1,1-Dichloroethene
c/s-1 ,2-Dichloroethene
1,2-Dichloropropane
Ethylbenzene
Hexachlorobutadiene
Isopropylbenzene
p-lsopropyltoluene
Methylene chloride
Naphthalene
n-Propylbenzene
Tetrachloroethene
Toluene
1 ,2,3-Trichlorobenzene
A,2,4-Trichlorobenzene
1 ,1 ,1 -Trichloroethane
Trichloroethene
Trichlorofluoromelhane
1 ,2,4-Trimethylbenzene
1 ,3.5-Trimethylbenzene
Vinyl chloride
Xylenes
RfD.
mg/kg-day
2.0E-01
1.0E-01
NO
9.0E-03
1.0E-02
1.14E-03(R)
1.0E-01
2.0E-04
4.0E-02
~
6.0E-02
4.0E-02
—
1.0E-02
2.0E-01
--
1.0E-02
NO
6.0E-03
3.0E-01
-
~
ND
2.0E+00
UF
100
1000

1000
3000

1000
1000
3000

1 100


1000
1000

1000


iodo



100
Reference
IRIS
HEAST
IRIS
IRIS
HEAST
IRIS
IRIS
HEAST
IRIS

IRIS
ECAO

IRIS
IRIS

* IRIS
IRIS
ECAO
IRIS


IRIS
IRIS
RfD,
mg/kg-day
5.7E-02
1.4E-01
ND
9.0E-03(R)
1.0E-02(R)
1.14E-03
2.9E-01
2.0E-04(R)
4.0E-02(R)
—
8.6E-01
4.0E-02(R)
--
1.0E-02(R)
1.1E-01
--
1.0E-02(R)
ND
6.0E-03(R)
2.0E-01
-
—
ND
2.0E+00(R)
UF
10000
1000



300
300



100








10000




Reference
HEAST
HEAST
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS

HEAST


IRIS
IRIS

IRIS
IRIS
IRIS
HEAST


IRIS
IRIS
Target and Critical Effect
rat: reduced body weight
rat: no observed effects

rat: hepatic lesions
rat: decreased hematocrit and hemoglobin
rat: hyperplasia, irritation of nasal mucosa
rat: liver and kidney toxicity
mouse: reanal tubule regeneration
rat: increased kidney weight

rat: liver toxicity


mouse: hepatotoxicity
rat: changes in kidney and liver weights

rat: increased adrenal wieghts


rat, mouse: increased mortality



rat: hyperactivity
ND a No data are available
- a Indicated that the chemical Is not located in the references
Toxcity criteria developed by ECAO were obtained from EPA Region IX
R = indicates that the value for the inhalation pathway was extrapolated from the oral SF/RfD
                                                                                3 Of 3

-------
                          Table 3-9
Summary of New Extraction Wells, Designed Extraction Rates, and Initial TCE
            Concentrations in Each HSZ in Main Base Plume
                   (5 ng/L TCE Capture Alternative)
Total No. of
Extraction Wells
19
12
1
2
No. of New
Extraction Wells
3
7
1
2
HSZ
Shallow
Upper Subshallow
Lower Subshallow
Confined
Total New
Extraction Well Rate (gpm)
500
850
200
250
Estimated Initial
TCE Cone. (ug/L)
.40 - 60
60-80
10-25
6-7
                            Pa
11

-------
                   Table 3-10
Summary of New Extraction Wells, Designed Extraction Rates, and Initial TCE
            Concentrations in Each HSZ in Main Base Plume
                   (3 iig/L TCE Capture Alternative)
Total No. of
Extraction Wells
22
13
2
2
No. of New
Extraction Wells
6
9
2
2
HSZ
Shallow
Upper Subshallow
Lower Subshallow
Confined
Total New
Extraction Well Rate (gpm)
750
1,000
280
320
Estimated Initial
TCE Cone. (ug/L)
25-45
30-65
8-12
6-13
                            Page 1 of 1

-------
                   Table 3-11
Summary of New Extraction Wells, Designed Extraction Rates, and Initial TCE
            Concentrations In Each HSZ In Main Base Plume
(v.s fig/L i us ua
Total No. of
Extraction Wells
22
14
3
3
No. of New
Extraction Wells
7
9 *
3
• 3
HSZ
Shallow
Upper Subshallow
Lower Subshallow
Confined
>iure Alternative;
Total New
Extraction Well Rate (gpm)
3,225
2,000
400
450
Estimated Initial
TCE Cone. (ug/L)
10-20
40-60
3-6
2-5
                           Paiflkof 1

-------
                     Table 3-12
Summary of New Extraction Wells, Designed Extraction Rates, and Initial TCE
             Concentrations In Each HSZ in Main TCE Plume
                     (Plume Control Alternative)
Total No. of
Extraction Wells
19
4
5
0
No. of New
Extraction Wells
3
0
5
0
HSZ
Shallow
Upper Subshallow
Lower Subshallow
Confined
Total New
Extraction Well Rate (gpm)
200
0
1.000
0
.Estimated Initial
TCE Cone. (ug/L)
.25-45
30-65
8-12
6-13
                            Page 1 of 1

-------
                                                                                                  Table 3-13
                                                                        Comparative Analysis of CERCLA Criteria for Main Base Plume
\!iS»MBUNiiHdilii^^

CRITERIA
Overall Protection of Human
Hultn ind ill* Environment
Compliance "llh Apollcablo or
Relevant and Appropriate
Requlrementa (ARARa)
Long-Term Eflecilveneaa ind
Permanence
Reduction ol Toitclly, Mobllltv, or
Volum*
Short-Term Ettectlveneu
ImpUmenlaolllty
COM
Agency Acceptance
Community Acceptance
loul SCOT*
Ranking
HT''"" '^t:. . ^L:.:._%;i:.£iTL'_: ••,".;..
IP.-:"'"^-- •..• . If" "" :,'• r. '. ' .YWSI'-'I^W T1F; vT
ksasr^.v Ir- :-••-.•. : .. -^rc^^^r-'-?^
J!
NR
NR
1
1
S
8
8
N/A
N/A
17
17
ill
NR
NR
2
2
4
4
4
N/A
N/A
18
11
i!
NR
NR
8
a
4
2
4
N/A
N/A
11
'r
= •••:.-
h
NR
NR
8
4
4
3
a
N/A
N/A
11
1
Hj
is
NR
NR
8
4
4 •
2
2
N/A
N/A
17
»•
S)
h
NR
NR
8
4
4
2
2
N/A
WA
17
8'
(I
NR
NR
8
4
2
1
3
WA
N/A
18
ir
|3»P^ir-aMII>»BMMMKiJKiiiiJ»
Kate 4?Kre^ i aitnittjiiFr
taw* ^ftMMnnmfiri>M»^>'
5
h
NR
NR
S
8
2
2
2
N/A
WA
16
10'
ii
is
NR
NR
8
S
2
1
1
N/A
N/A
14
ir
9
l!
NR
NR
8
S
2
1
1
N/A
N/A
14
,8"
VtPOtstfMH&RtSiitlitl&iifiNMt^E&^^^^^SMfBiBi^RfA
SSSS^SSSSSSSrSSSSSSSflSiKSSSSSSSSSSSSifffifSCtmffiiUtfm^^
af
Si
NR
NR
s
3
3
2
4
N/A
N/A
17
e-
a
r
NR
NR
S
4
3
3
3
N/A
N/A
18
4*
if
NR
NR
8
4
3
2
2
N/A
N/A
18
14'
9
r
NR
NR
8
4
3
2
2
N/A
N/A
18
ir
*!
is
NR
NR
4
3
4
3
4
N/A
' N/A
18
S'
•Bta«ii
naniiiicy
Miifg*3*&
S
h
i ^
NR
NR
4
3
4
4
4
N/A
N/A
IB
3'
9WI3BG
fljPP^JlPI
rwmy
J«»«W1

^SB^KBBJ
S|
i§
NR
NR
4
3
4
3
3
N/A
N/A
17
ir
3'
h
ii
NR
NR
4
3
4
3 '
4
N/A
N/A
18
r
NR . ThMi ertlirl* ire not nmkod bociuM Ihoy mat b* cofflptad ««h. i m IMmiiV* «**»> U not pro(»dr»» or downol comply w«h AflARj, miHlttm«»v»cmnnotl)«»«l»ct»<).

-------
                                                                                             Tabl«3-13
                                                                    Comparative Analysis of CERCLA Criteria (or Main Base Plum*
        CRITERIA
Omnl Protection ol HUM*
H**lh ind tlw InvXm limit
                     s.
ComphM* wtt Appfcrnbto w
Rttorint ind Affrotffcte
A«*ilrMnMt»(AltAIU)
LonfhTwm BIMUVWM** (Ml
RftOUOttofl Of T OKIBVJfi
Vetaim
                     i Of
ttwrt-Twm CltMtkwMM
Ceo
                           NM
                                   NM
                                            NM
                                                    NM
                                                             NM
                                                                      NM
                                                                               NM
                                                                                         NM
                                                                                                  NM
                                                                                                            NM
                                                                                                                      NM
                                                                                                                                NM
                                                                                                                                          NM
                                                                                                                                                    NM
                                                                                                                                                              NM
                                                                                                                                                                        NM
                                                                                                                                                                                  NM
                                                                                                                                                                                            NM
                           NM
                                   NM
                                            NM
                                                    NM
                                                             NA
                                                                      NM
                                                                               NM
                                                                                         NM
                                                                                                  NM
                                                                                                            NM
                                                                                                                      NM
                                                                                                                                NM
                                                                                                                                          NM
                                                                                                                                                    NM
                                                                                                                                                              NM
                                                                                                                                                                        N/A
                                                                                                                                                                                  NM
                                                                                                                                                                                            N/A
Tout (eon
                           03
                                    21
                                                                               25
                                                                                         29
                                                                                                   24
                                                                                                             24
                                                                                                                       26
                                                                                                                                 27
                                                                                                                                           28
                                                                                                                                                    28
                                                                                                                                                               2«
                                                                                                                                                                         27
fUrtthfl
                           17
                                    11
                                                     i""
                                                                               ir
14*
         .18*
                                                                                                                                          14*
                                                                                                                                                                                  H«
                                                                                             P»t«1o(1

-------
                                                                                Table 3-14
                                                    Comparative Analysis of CERCLA Criteria for East Base Plumes

CRITERIA


Overall Protection of Human
HMltti and In* EnvlrenniMil
Compliance with Applicable or
Relevant end Appropriate
Requlrementa(ARARa)
Long-Term EftaeflvtnM* and
Ptrmananea
Raduetlon ol Torielty, Mobility, or
Volume
Short-Twin EHecttveneaa
ImplamantaMllly
Coal
Agancy Aceaptanea
Community Aeeaptanea
Total Seora
Ranking
„

i i '"
ig
NR

NR

1
1
S
s
5
N/A
N/A
17
11*
1 A
1||
•••'Is
ill
NR

NR

3
3
5
S
5
N/A
N/A
21
r
3.
Ji
1 g
is
NR

NR

5
3
4
3
3
N/A
N/A
18
4*
B _
«• S
||
I TJ
§ °
3 >
NR

NR

5
4
4
4
2
N/A
N/A
19
3'
u
m
Is
13
»
NR

NR

5
4
4
4
2
N/A
N/A
19
2*
**
|f
1 1
§5
NR

NR

5
4
2
2
2
N/A
N/A
15
10'
5c
11
1
§
NR

NR

5
5
2
3
1
N/A
N/A
16
9'
$
io
is
h
NR

NR

5
5
2
3
1
N/A
N/A
16
8'
2.
if
i §
52
NR

NR

5
3
3
3
3
N/A
N/A
17
7* I
n _
10 S
if
| O
§ >
NR

NR

S
4
3
4
2
N/A
N/A
18
6*
U
ID
)o
3
5
NR

NR

5
4
3
4
2
N/A
N/A
18
5'
NR a Thasa criteria am not rankad bacaua* thay muat ba oomptod with. H an aflamattv* which la not protaettva or does not comply with ARARs, that altamatlva cannot be aeleded.
                                                                                       oil

-------
                     Table 3-15
Cost Comparison for the Main Base Plumes Remedial Alternatives
Remedial Alternatives for Groundwater Remediation
Main Plume Costs




Capital Costs
O&M Costs (present worth)
Total Present Worth

Capital Costs
O&M Costs (present worth)
Total Present Worth
-
Capital Costs
O&M Costs (present worth)
Total Present Worth

Capital Costs
O&M Costs (present worth)
Total Present Worth
No Action
Well Head Treatment
Institutional Response


Alternative 1
$0
$2.926,000
$2,926,000





Alternative 2
$2,994,000
$9.356,000
$12,350,000

Atr Stripping
%
O
q.
UV Oxidation
L-PGAC
Groundwater Extraction Treatment A Disposal;.! :
5 pg/L TCE Capture
Canal Discharge .
Alternative 3A
$7.665.000
$8,075,000
$15,740,000
Alternative 38
$9,640,000
$13.244.000
$22.884,000
Injection
Alternative 3C
$19,314.000
$15,185.000
$34,499,000
Alternative 3D
$20,097.000
$13.338,000
$33.435,000
Alternative 4
0.5 pg/L TCE Capture
Canal Discharge
Alternative 4A
$13.141,000
$12,767,000
$25,908,000
Alternative 4B
$16.635,000
$21.808,000
$38.443.000
Injection
Alternative 4C
$27,894,000
$25.160.000
$53.054.000
Alternative 4D
$29.267.000
$21.922.000
$51.189.000
Alternative 5
3 pg/L TCE Capture
Canal Discharge
Alternative SA
$9,665.000
$10.131.000
$19,796,000
Alternative 5B
' $12.132,000
$16.587.000
$28.719.000
Injection
Alternative 5C
$22.320.000
$18.953.000
$41,273.000
Alternative 5D
$23.300.000
$16.690.000
$39.990.000
AltemauV* 6
Plume Control
Canal Discharge
Alternative 5A
$5.166.000
$7,266.000
$12,432.000
Alternative 5B
$6.647.000
$11.148.000
$17.795.000
Injection
Alternative 5C
$9.225.000
$12.570.000
$21.795.000
Alternative 5D
$9.813.000
$11.189.000
$21.002.000
                         Page 1 of 1

-------
                                       Table 3-16

                   Cost Comparison for the East Base Plumes Remedial Alternatives
                         Remedial AHernatlves for Grbundwater Remediation
East Base Plume Costs
                          ^ J^; *«
                                       ,'f  ''••<•+• >,-*»  •;
                                       it   *£'-;;''•<..&,

                                       / ;~'J^-£t
                             Institutional Response
                          Alternative 1  I Alternative 2
                                  Groundwater Extraction

                                   Treatment & injection
                                                                     Alternative 3
                                                                  5 ug/L TCE Capture
                       Alternative 3A
                         Alternative 38
                           Alternative dC
Capital Costs
      $0
  $9,000
$2.485.000
$2,786.000
$2,979.000
O&M Costs (present worth)
$529,000
$529,000
$1,495,000
$3,238,000
$2,854,000
Total Present Worth
$529,000
$538,000
$3,980,000
$6,024,000
$5,833,000
                                                                 0.5 pg/LTCE Capture
O&M Costs (present worth)
O&M Costs (present worth)
                                           Page 1 of 1

-------
                    Table 3-17
Compliance with Applicable or Relevant and Appropriate
           Requirements Main Base Plume

Alternative
Alternative 1
Alternative 2
Alternative 3
Alternative 4
Alternative 5
Alternative 6
Compliance with ARARs
Not a remedial action under the Comprehensive Environmental Response,
Compensation, and Liability Act
Not expected to comply with state groundwater protection standards that require
cleanup and abatement of effects of discharge to attain background water quality or
best water quality if background is not technically or economically feasible
Comply with state groundwater protection standards if it is determined that achieving
lower levels of cleanup is not technically or economically feasible
Meets all chemical- and action-specific ARARs
Comply with state groundwater protection standards if it is determined that achieving
lower levels of cleanup is not technically or economically feasible
Probably not comply with state groundwater protection ARARs

-------
                    Table 3-18
Compliance with Applicable or Relevant and Appropriate
                   Requirements
                  East Base Plume
Alternative
Alternative 1
Alternative 2
Alternative 3 .
Alternative 4
Alternative 5
Compliance with ARARs
Not a remedial action under the Comprehensive Environmental Response.
Compensation, and Liability Act
Not expected to comply with state groundwater protection standards that require
cleanup and abatement of effects of discharge to attain background water quality or
best water quality if background is not technically or economically feasible
Comply with state groundwater protection standards if it is determined that achieving
lower levels of cleanup is not technically or economically feasible
Meets all chemical- and action-specific ARARs
Comply with state groundwater protection standards if it is determined that achieving
lower levels of cleanup is not technically or economically feasible

-------
Table 4-1. Chemical-Specific ARARs for Drinking and Groundwater
             Chemical
       Concentration (ng/L)
      Plumes
 Benzene
 Carbon Tetrachloride
 Chloroform
 cis-l,2-Dichloroethene (cis 1,2-DCE)
 Di-ethylhexyl phthalate (DEHP)
 Tetrachloroethylene (PCE)
 Trichloroethene (TCE)
              1.0'
              0.5'
              1002
              6.0'
              4.0'
              5.02
              5.02
       MBP
       MBP
       MBP
     MBP.CVP
       NBP
  MBP,  CVP.NBP
MBP, EBP, NBP, LF1
pg/L = micrograms per liter
MBP = Main Base Plume
CVP=Castle Vista Plume
EBP=East Base Plume
ARARs = applicable or relevant and appropriate
         requirements
NBP= North Base Plume
LFl=Landfill 1 Plume
'"     California MCL

<2)     Federal MCL
California Regional Water Quality Control Board Central Valley Region (CVRWQB),
"A Compilation of Water Quality Goals," July 1995.

-------
Table 4-2. Action Specific ARARs
     [Revised 3/7/97 - Final]
,:m^*W,Km:,, , , , ...,. ,. : ^m^: ; • -^^igiaHHMM
Federal Safe
Drinking Water
Act
California
Hazardous Waste
Control Law
40 CFR 144 - Underground Injection
Contra! Program
Title 22. CCR. Division 4.5
(Environmental Health Standards for
Management of Hazardous Waste). Chapter
14 (Standards for Owners and Operators of
Hazardous Waste Transfer, Treatment,
Storage, and Disposal Facilities), Article 9
(Use and Management of Containers)
22 CCR 66264.94
22 CCR 66264. 171
22 CCR 66264. 172
22 CCR 66264. 173
22 CCR 66264. 174
22 CCR 66264. 175
22 CCR 66264. 176
22 CCR 66264.177
22 CCR 66264.178
22 CCR 66265.94
Applicable
Subsections as
Listed Below
Relevant and
Appropriate*
Relevant and
Appropriate
Relevant and
Appropriate1
Relevant and
Appropriate'
Relevant and
Appropriate'
Relevant and
Appropriate
Relevant and
Appropriate'
Relevant and
Appropriate'
Relevant and
Appropriate'
Relevant and
Appropriate1
EPA established substantive requirements for actions that involve injection of fluids into subsurface
through wells. The injection can not cause a violation of primary MCLs, must be maintained, must be
monitored, and injection can not take place until the well construction is complete.
This regulation applies to (he technologies selected for the cleanup of groundwater plumes for which
fluids are reinjected.
The management of contaminated waste will be consistent with RCRA requirements.
Addresses concentration limits for water quality monitoring of permitted facility
Addresses use of containers that are in good condition
Addresses use of containers to store the recovered product that are compatible with this material
Specifies that containers must be closed during transfer
Addresses inspection of containers
Addresses providing adequate secondary containment for the waste stored
Addresses isolating the waste from sources of ignition (if the material is ignitable)
Addresses segregating the waste from incompatible wastes
Specifies that all hazardous material must be removed at closure
Concentration Limits for water quality monitoring of interim slams facility
             Paoe.1

-------
                                                             Table 4-2.  Action Specific ARARs
                                                                     [Revised 3/7/97 - Final]
                                                                               DescHpTionrofvVpplicableor:R«leva5
          Slatt of California Air ARARs
California Clean
Air Act
SJVUAPCD Rule 2201
Section 4.1
Applicable
This section of the role requires the installation of Best Available Control Technology (BACT) to a new
emissions unit or modification of an existing emissions unit that will result in an emission of ROG.
NOx, SOx, PM10. or CO.

BACT for any emission unit is the most stringent of the following:

•    The most effective emission control device, emission limit or technique, singly or in combination,
     which has been required or used for the type of equipment comprising such an emissions unit For
     this type of process, a control efficiency (effluent/influent) of 95 percent is considered BACT.

•    Top-down analysis process is the selection of any alternative basic equipment, fuel, process,
     emission control device or technique, singly or in combination, determined to be technically
     feasible and cost-effective by the SJVUAPCD.

•    In making a BACT determination for each affected pollutant the Air Force will consider the overall
     effect on other affected pollutants.

This regulation will apply to the treatment processes that release or cause to be released the pollutants
listed in the regulation. The remedial alternatives utilizing air strippers  must ensure BACT is used to
control emissions in excess of levels specified in the rule.  The technology chosen will meet this
requirement	
California Clean
Air Act
SJVUAPCD Rule 2201
Section 4.2
Applicable
This section of the rule requires an applicant to provide offsets for any stationary source with the
potential to emit any pollutant in excess of the levels shown below.

          PM10....80lbs/day

All emission increases in excess of the levels specified above need to be offset for the same calendar
quarter.

Emissions are determined by using actual stack test data, emission factors, engineering calculations, or
other methods in accordance with Section 6.0 of Rule 2201.

This regulation will apply to the treatment processes that release or cause to be released the pollutants
listed in the regulation. The remedial alternatives utilizing air strippers must ensure offsets are used for
emissions in excess of levels specified in the rule.
                                                                                 Page 2

-------
Table 4-2. Action Specific ARARs
     [Revised 3/7/97 - Final]
iiiii
California Clean
Air Act
California Clean
Air Ad
California Clean
Air Act
^^Standai^Requlreiiient^v •
^critlSferli;iSi6tibn';.-:;-^
SJVUAPCDRule4l02
SJVUAPCD Rule 8010
SJVUAPCD Rule 4201
. i^ARAR'.-^v
S^Stetus^
Applicable
Applicable
Applicable
Stati of California GroundwaUrARARs
Federal dean
Water Act (40
CFRI22)
40 CFR 122 - EPA Administered Permit
Programs: The Nadonal Pollution
Discharge Elimination System (NPDES) *
40 CFR 122.26
NPOES. Stormwater portions of NPDES
Permit No. CA0083976.
Subsections(s) as
Listed Below
Applicable
Applicable
^^i^^^^^H^HttfHffff(
This rule prohibits the discharge of air contaminants in quantifies which cause injury, detriment,
nuisance, or annoyance to any considerable number of persons or which endangers the comfort,
response, health, or safety of any such person or which causes or has natural tendency to cause injury or
damage to business or property.
This regulation is applicable to any remedial action activity, which may discharge air contaminants as
defined by the rule.
This rule requires a person to take every reasonable precaution not to cause or allow emissions of
fugitive dusts from being airborne beyond the properly line from which the emissions originated.
This regulation is applicable to any remedial action activity, which may cause the release of fugitive
dust.
This rule prohibits the discharge of particulate matter from any source in excess of 0. 1 grains per
standard cubic foot.
This regulation is applicable to any remedial action activity, which may cause the release of particulate
matter.
• '. • .lO1-.. •:. . .-..'•
Requirements to ensure stormwater discharges from Castle AFB remedial action activities do not
contribute to a violation of surface water quality standards.
Stormwater permit requirements
Requirements to ensure stormwater discharges do not contribute to a violation of surface water quality
standards.
Apply to stormwater discharges from industrial areas and construction sites. Includes measures to
minimize and/or eliminate pollutants in stormwater discharges, and monitoring to demonstrate
compliance.
To the extent that permit » CA0083976 relates to stormwater practices at Castle AFB, its requirements
are applicable. The Air Force believes the portions of the permit which purport to regulate onsile
discharges from CERCLA groundwaier cleanup ore unenforceable. Groundwater cleanup at Castle is
properly regulated under CERCLA and the requirements of this ROD.

-------
Table 4-2. Action Specific ARARs
     [Revised 3/7/97 - Final]

Federal Clean
Water Act and
Porter-Cologne
Water Quality
Control Act
(California Water
Code Sections
13233. 13243.
13267. 13370c.
13370.5)
•'xfjJA Standard; Requirement,
^lg:enteri()h;'or imitation < > '
40 CFR 122 - EPA Administered Permit
Programs: TheNPDES.
40 CFR I22.41(d). (e). (j)(0. (3),(4). (l)(6).
(m), and (n)
40CFRI22.44(d).(g).and(i)
40 CFR 1 22.45 (c), (d). (e), (0. and (g)
40 CFR 122.48 (a) and (b)
ARAR
Status :
Subscclions(s) as
Listed Below
Applicable
Applicable
Applicable
Applicable
Description of Applicable or Relevant and AppropriatejRequJremejQtsdK*^fe&
These sections are the substantive requirements of a NPDES permit. They relate to effluent limitations
and monitoring requirements and should be applied during development of the monitoring plan.
The RWQCB is authorized to implement the NPDES program. The Air Force will coordinate with EPA
and the Regional Water Board when following the NPDES ARARs. The Air Force does not recognize
the procedural portions of the NPDES process nor the necessity to get a permit
Duty to mitigate, proper operations and maintenance, monitoring and records, twenty-four hour
reporting, bypass and upset requirements
Water quality standards, twenty-four hour reporting, and monitoring requirements
Calculating metals, setting limitations on continuous and noncontinuous discharges, mass limitations,
and adjusting for pollutants in intake water.
Requirements of maintenance and types of monitoring
            Page 4

-------
Table 4-2. Action Specific ARARs
     [Revised 3/7/97 - Final]
$£pW$*T;:^
i^Sdarcef;--"!'
Porter-Cologne
Water Quality
Control Act
(California Water
Code Sections
13000. 13140.
13240)






















Porter-Cologne
Water Quality
Control Act
(California Water
Code Sections
13000. 13140.
13240)
,«• Staridari, Requirement, Criterion, .
Hff>;*^$iOr liimitatidn^h;^' •:•/,••
RWQCB CVR Basin Plan "Water Quality
Objectives for Inland Surface Waters" and
"Water Quality Objectives for Ground Water"









•'










RWQCB. CVR Basin Plan. "Policy for
Investigation and Cleanup of Contaminated
Sites."
Section 1

Section h
RWQCB. CVR Basin Plan. "Policy for
Application of Water Quality Objectives"





ARAR Status
:*;. '.'•• ' ...
Applicable






















Sections as
indicated below

Relevant and
Appropriate1
Applicable
Applicable






.i^M JJMHBJfllBit Jill
Description of 'Applicable or Relevant afa ^Apprp^ril^||^^at5j^Bm
Establishes water quality objectives, including narrative and numerical standards, that protect the 1
beneficial uses of surface and groundwater in the region. The designated beneficial uses are
municipal and domestic; agricultural: and industrial supply.

Specific applicable portions of the Basin Plan include beneficial uses of affected water bodies and
water quality objectives to protect those uses.

Toxicity section requires that discharge not cause aquatic communities and populations, including
vertebrate, invertebrate and plant species, to be degraded and requires toxic pollutants not to be
present in the water column, sediments, or biota in concentrations under certain circumstances
specified in the objective.
Survival of aquatic organisms in 96-hour bioassays of undiluted waste shall be no less than:
minimum for an one bioassay 70%
Median for any three or more consecutive bioassays 90%
Chronic toxicity monitoring will be conducted to determine whether the effluent is contributing
toxicily lo the irrigation canal. The testing will be conducted as specified in EPA 600/4 89 001 .
Chronic toxicily samples shall be collected immediately prior lo the confluence of the West Base
Drain and Canal Creek. Sampling will coincide with Receiving Water Sampling throughout the
year, and Stormwater Sampling from October through April, unless otherwise specified in the
sampling and monitoring plan.
California state MCLs or SMCLs are applicable to the extent the state MCLs and SMCLs are more
stringent than federal MCLs and SMCLs. Only promulgated state SMCLs are applicable; all other
SMCLs are To Be Considered (TBCs).
Establishes and describes policy for investigation and remediation of contaminated sites. Also
includes implementation actions for setting groundwater and soil cleanup levels.

Water Quality assessment to determine impacts and threats to the quality of water resources.

Compliance with groundwater cleanup levels must occur throughout the pollutant plume.
This policy defines water quality objectives and explains how the Regional Water Board applies
numerical and narrative water quality objectives to ensure the reasonable protection of beneficial
uses of water. Applies to all cleanups of discharges that may affect water quality.

The portion of this section which describes the process by which narrative water quality objectives
are used to determine numeric values is considered in determining the cleanup levels in this ROD.


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                                                             Table 4-2.  AcTOn Specific ARARs
                                                                    [Revised 3/7/97 - Final]
                                                                                         5L*ki?**""• «"  1.1 -"ti'i''!w»v
                                                                                         iptitm of Applicable or Relevant
                   SWRCB Resolution 68-16
                                                Applicable
                   The resolution establishes requirements for activities involving discharges of contamination
                   directly into surface water or groundwater (e.g.. quality of pump and treat effluent into surface
                   water or groundwater).

                   Substantive requirements established by the resolution include use of "best practicable treatment or
                   control" for discharging the effluent.

                   This regulation applies to remedial action activities that cause active discharges to surface water or
                   groundwater.
                   SWRCB Resolution 88-63
                                                Applicable
                   Specifies that, with certain exceptions, all ground and surface water have the beneficial use of
                   municipal or domestic water supply. Applies in determining beneficial uses for water that may be
                   affected by discharges of waste.

                   SWRCB Resolution 88-63 applies to all sites that may be affected by discharges of waste to
                   groundwater or surface water. The resolution specifies that, with certain exceptions, all
                   groondwater and surface water have beneficial use of municipal or domestic water supply.
                   Consequently, California Slate primary MCU are relevant and appropriate, however the most
                   stringent federal or stale standard will be the ARAR for the remedial action. California standards
                   which may be ARARs for the site(s) are found in 22 CCR 66435.22 CCR 64444.5, and 22 CCR
                   64473.
Porter-Cologne
Water Quality
Control Act
(California Water
Code Sections
13140.13240.
13260.13263,
13267,13300.
13304, 13307)
SWRCB Resolution 92-49
(«s amended April 21,1994)
Subparagraph IIIO
  Relevant and
  Appropriate'
Section IIIO directs the Water Boards to ensure dischargers clean up and abate the "effects" of
discharges in a manner promoting attainment of either background water quality or the best
reasonable water quality if background quality is not feasible (feasibility determined by factors
listed in Section IIIG and 23 CCR Chapter 15, Section 2550.4).  Minimum water standards must be
protective of beneficial use.

Section IIIG directs the Water Board to apply 23 CCR Chapter 15, Section 2550.4 in approving
any alternative cleanup levels less stringent than background quality and to apply 23 CCR
Chapter 16, Section 2725 for alternatives cleanup levels for remediation of releases from USTs.
 Porter-Cologne
 Water Quality
 Control Act
 (California
 Water Code
 Sections  13140-
 13147,13172,
 13260.13263.
 13267,13304)
Title 23, CCR, Division 3. Chapter 15 (Section
25IOetseq.)
Subsections as
listed below3
 Applies minimum waste management standards for discharges of waste to land for treatment,
 storage, or disposal that may affect water quality. The application of specific sections of Chapter
 15 that are ARARs are discussed below.
                                                                                Page 6

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                                                             Table 4-2.  Action Specific ARARs
                                                                     [Revised 3/7/97 - Final]
                                                               .lARAR Status^
                                                                                   Dwcnpdoh of Applicable or Relevant
                    Title 23, CCR. Section 251 l(d)
                                              Relevant and
                                              Appropriate
                   Wastes removed from the immediate place of release must be discharged in accordance with the
                   classification and siting requirements of Chapter IS. Wastes contained or left in place must
                   comply with applicable provisions of Chapter 15 to the extent feasible.

                   Applies to all actions taken by or at the direction of public agencies to clean up unintentional or
                   unauthorized discharges of waste to the environment.
                    Title 23. CCR. Section 2550.4
                                              Relevant and
                                              Appropriate
                   Cleanup levels must be set at background concentration levels, or if background levels are not
                   technologically and economically feasible, then at the lowest levels that are economically and
                   technologically achievable. Specific factors must be considered in setting cleanup levels above
                   background levels.  Cleanup levels above background levels shall be evaluated every five years. If
                   the actual concentration of a constituent is lower than its associated cleanup level, the cleanup
                   level shall be lowered to reflect existing water quality.

                   Applies in setting groundwater cleanup levels for all discharges of waste to land.
                   Title 23. CCR. Section 2550.7
                                             Relevant and
                                             Appropriate
                   Requires general groundwater monitoring.

                   Applies to all areas at which waste has been discharged to land.
                   Title. 23. CCR. Section 2550.9
                                             Relevant and
                                             Appropriate
                   Requires on assessment of the nature and extent of the release, including a determination of the
                   spatial distribution and concentration of each constituent.

                   Applies to areas at which monitoring results show statistically significant evidence of a release.
                   Tide 23, CCR. Section 2550.10
                                             Relevant and
                                             Appropriate
                   Requires monitoring to determine the effectiveness of the cleanup.

                   Applies to all groundwater cleanup activities.       	
California Safe
Drinking Water
Act (California
Health & Safety
Code Section
40IOetseq.)
Title 22, CCR. Division 4, Chapter 15. Articles
4. 5.5. and 8
Relevant and
Appropriate
Requirements for public water systems. Includes Maximum Contaminant Levels (MCLs) and
Secondary Maximum Contaminant Levels (SMCLs).

Relevant and appropriate for setting water quality objectives for groundwaler to the extent the
slate MCLs and SMCLs are more stringent than federal MCLs and SMCLs.  State promulgated
SMCLs are relevant and appropriate; all other SMCLs are To Be Considered (TBCs).
Safe Drinking
Water and Toxic
Enforcement Act
of 1986.
'Proposition 65*
(California
Health & Safely
Code Section
25249.5 etseq.)
Health and Safely Code Section 25249.5; Title
22, CCR. Division 2, Subdivision I, Chapter 3
Relevant and
Appropriate
Prohibits the discharge or release  of a significant amount of any chemical known to the Slate of
California to cause cancer or reproductive toxicity to water or to land where the chemical will
probably pass through a source of drinking water.

Relevant and appropriate for discharges to a source of drinking water.

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                                                             Table 4-2.  Action Specific ARARs
                                                                    [Revised 3/7/97 - Final]
                                                                                          . ,                                 ,. _„.,
                                                                              Description of Applicable or Relevant andjAppjopria
  Other Stati ofCoUforniaAMRi
  40 CFR 122 122.26
Fish and Game Code
                        Sections 5650
Subsection(s) as
 Listed Below
 Relevant and
  Appropriate
It is unlawful to deposit in. permit to pass into, or place where it can pass into the waters of this state any
material listed in Fish and Came Code Sections 5650 and 5652.
AFB = Air Force Base
BACT = Best Available Control Technology
CCR = California Code of Regulations
CFR = Code of Federal Regulation
COC = contaminant of concern
DWQ = Department of Water Quality
NOx s nitrogen oxide
ppb B parts per billion
RCRA = Resource Conservation and Recovery Act
RWQCB = Regional Water Quality Control Board
SOx = sulfur oxide
USEPA = United States Environmental Protection Agency
     ARAR = applicable or relevant and appropriate requirement
     BMP = Best Management Practice
     CERCLA = Comprehensive Environmental Response. Compensation, and Liability Act
     CO a carbon monoxide
     CVR 3 Central Valley Region
     MCL = maximum contaminant level
     PM10 = paniculate matter
     ppm = parts per million
     ROC - reactive organic gas
     SJVUAPCD a San Joaquin Valley Unified Air Pollution Control District
     SWRCB = Stale Water Resource Control Board
     UST = underground storage lank
1  The following standard is set forth in Title 22 CCR section 66264.94. Title 22 CCR section 66265.94. Title 23 CCR section 2S50.4. and SWRCB Res. No. 92-49 section I1IG:

  Concentration limits for a constituent of concern greater than background values for that constituent can be established only if it is demonstrated that it is technologically or economically infeasible
  to achieve the background value for that constituent; in no event shall a concentration limit greater than background for a constituent of concern exceed the lowest concentration that is
  technologically or economically achievable.

  Deportment of Defense (DOD), the Air Force, and EPA reserve their position that this standard is a Federal ARAR via its incorporation in Title 22 CCR section 66264.94 which was federally
  authorized via EPA's authorization of the Slate of California RCRA program. DTSC and SWRCB reserve their legal position that this standard is an applicable state requirement promulgated under
  slate law. The parties agree that the substantive requirement is being met by the remedial actions.

'  DOD's legal position is that Title 23 CCR. division 3, chapter 15, is an ARAR only as invoked by Section 2511(d). The RWQCB disagrees with this and reserves its legal position.
                                                                               PageS

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TABLE 4-3
TREATED GROUND WATER DISCHARGE STANDARDS

Constituent
Acetone
Benzene
Bromoform
Carbon Tetrachloride
Chloroethane
Chloroform
Chloromethane
Chlorobenzene
Dibromochloropropane (DBCP)
Diethylhexyl phthalate (DEHP)
Dichlorobenzene (ortho)
Dichlorbenzene (para)
Dichlorodifluoromethane
,1DCE
,2, DCE (cis)
,2, DCE (trans)
.1DCA
,2,DCA
,2 Dichloropropane
Ethylbenzene
Ethlylene Dibromide
Methylene Chloride
PCE
Toluene
Trichlorofluoromethane
TCE
VOCs
Xylene

Diesel or Kerosene
TPH (gas)
TPH (Diesel)

Iron
Manganese
Nitrates

Other constituents
coc

YES1

YES1

YES'



YES6




YESU







YESU-'


YES1-2-4'6












Standards for Discharge •
30 Day Median (pg/L)
1
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.35
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.14
0.5
0.5
0.5
0.54
0.5
1
0.5

10
10
50

.
-
.

Daily Maximum (ug/L)
-
1
1
0.5
1
1
1
1
5
1





1
1
0.5
1
29
0.5
1
1
42
1
1
5
17

10
100
100

300"
50"
10 mg/L as Nitrogen"

All other constituents must be within background
concentrations in the receiving water at the point of
discharge. If this is not technically feasible, discharge
standards may be established.
'COC for East Base Plume    5 COC for Undfill 4 Plume
1 COC for Castle Vista Plume  * COC for North Base Plume

' For discharge into the contaminated regions of an aquifer, in lieu of the standards in this table, treated water cannot be discharged at concentrations that
exceed the specified aquifer cleanup level or the actual concentrations in the aquifer at the point of discharge, whichever is lower. For constituents where
no aquifer cleanup level has been specified, treated water cannot be discharged at constituents concentrations that exceed the actual concentrations at the
point of discharge for that constituents prior to any discharge.

"or 93% UTL background at point of discharge, if higher.
General Note:  All COC's will be included in routine Long-Tenn Groundwater Monitoring; other constituents will be sampled according to the approved
LTGSP sampling plan.

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Figures

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                CASTLE
                  RPORT
                LOCATION OF CASTLE AIRPORT
 FORMERLY CASTLE AIR FORCE BASE, CALIFORNIA
                                   f**stl* Aimnrt
Figure 3-1

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                                       _ 	
                             br AoooptaMd*pou» 'toot

                             >« femiin o( fctog*****
      • untf !•«••• •nam «
      Mn 5 to 10 IM. 1o M
                  120
 S5 IMI  BCS Oman miutr  of
  	
     O0afc9c
        ***'" 6°""9 S~to*
Gfovol telling •odwnonlB fnotitr
•onoolll OU1 tnd OUJ TCE Pbmol.
fcourt on boMfi pMt. Two pwiol
   .                 ,.
«M. «• «M ofMBS.  Mini.II. fc
M». M>j>o fen uigniOi
•ma kvnfoMd fc yiviol ta
KdtaMi k t» vh. •»«. Md
      •uoaoium
by feed pkui dopotti. Biodod
• r>l<>  oinlblll  mk.lloi.
 	M*   -
                                                                                                                           (SoonJCtoytl               "


                                                                                                                        GENERALIZED BASEWIDE CONCEPTUAL MODEl

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 lEQENO
 • MWOOI   Monrtoring We«       -   Oraunitwater Elmttofi Contour in  NOTE:      1
 • 04740   OomollicWWI       'XX r*it Atoov* Mun &M UMl IMSU  Only Monitoring WW« IMW. JM. TW
 • PW15    Production Well         •—                       tndOA4>«niw«edfor W«er £l«viiion
   11-01
   MIDI
IrngjiionWeD-Oonwiile  •""'.MM location with
Irrigation Well-Public        uioundwiur Elevation Data
Monitoring.
  • AMI!    Municipal Well
                           ABO  Abandoned VWeil
|
5
                                            GROUNDWATER ELfVATION CONTOURS, FIRST QUARTER 1995
                                  (JANUARY 9 TO JANUARY 18) CONFINED HYOROSTRATIGRAPHIC ZONE

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                                CASTLE

                             AIR FORCE BASE
           	-T^-^
      BELLEVUE
    LOCATION MAP
CALIFORNIA
          Site Locatioi(
Castle AFB, California
                            Figure 3-4

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                              OLIVE   AVENUE
ATWATER
                         CASTLE VISTA
                FIGURE 3-5

-------
••1
f
3
      B     BUILDING
      BT    BUILDING TEMPORARY
      DA    DISCHARGE AREA
      DP    DISPOSAL PIT
      ETC    EARTH TECHNOLOGY CORPORATION
      n     FUEL SPILL
      n     FIRING RANGE
      FTA    FIRE TRAINING AREA
      HUB    HAZARDOUS WASTE STORAGE
      If     LANDFIIL
8T
                                             TCE CONCENTRATION CONTOURS (IN u5A)
                                             2nd QUARTER. 1994
                                             PLUME REGION BOUNDARY
                                             BASE BOUNDARY

                                             GENERALIZED BOUNDARIES
                                             OF SCOU SITES
PC8   POLYCHLORINATEO OTHENYLS
m*  pa Fua FARM AREA
8     STRUCTURE
BA    STORAGE AREA
S3    SANITARY SEWER     '
flTA   STAIN
      STRUCTURE TEMPORARY
      SOLID WASTE MANAGEMENT UNIT
TOCI   TEST CENTER COMPLEX I
(JR.   UNDERGROUND FUEL LEAK
                         PLUME REGIONS, POTENTIAL SOURCE AREAS.
                                       AND SHALLOW HSZ O2 1994 TCE
                                               PLUME DELINEATION MAP
                                                                  CoiUe Airport
                                                                                                                     ••I

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                                       CB Groundwater Remedial Investigation
                                                 Identification of Analyte* That Excaad
                                                Background for Each Plum* Reglon/HSZ
                                                           (See. 8-2.7 J)
                                                  It Maxmuim Conoanantton of Inorganic
                                                Anafyte Less Than Threshold Braoround
                                                    (TBVP TBV for Orpanc- ' veto
                                              NO
                                                       Inorganic Anar/ies Deleted
                                                       frem Fvrtnor ConueenMn

                                                   ArtyiM Delete* Beiylium. CaOrwn.
                                                      ton. Manganese. Poassum.
                                               Selenium. ThjBojm, GnMa Alpn* Pane* Radiation




CB Grcjndwatcr Baseline

Identification of Classes c' Compoun
(S«c.4i-J)
la Analyte a Ctau r Compounds?
Human Health Risk Assessment

» I N".

M*nffficition of Ctntnl Mnants/lon*
* (Sec. 4.2.1 J)
Is Anatyte a Gcnen: Mineral or Ion?


                                               VHS
                                     | YES

                            C. Cnu beta '
                                                                              AnaiyiM DetotM CMond*.
NO ,


KwfinffC9Don of csAWTtuI MuMtyntv
(SM.O.1J)
Is Aralyta an Eswntia. Nutiienf?

I N0 .
Evaluation Of Riska and
Haarda from COPCa for
Each Pimm RcgienftfSZ
(S«c. 7 J-7 J)

h
                                               YES
                                      torn furmr C«nsn*own

                                    AnalrM (MMnt CMCMD. Ccpiwr.
                                      mgn.Hu.il. SatiOT. Zinc
                                           CB Groundwater Feasibility Study
                                  1. Evaluation Of COPCa With
                                 Raspacl To Ragfonal Oceuranca
                                      (Sac. 2.1 and Z2)
                              Is Concentration of COPC Charaaeristic
                                 Of Natmi Ragtonal Groundwater
                                 Concantntiona (a.p, AnanK) or
                              OvaracttrtBic of Raojona) CeUMim
                                   Oua to Noo-CAFB Soureaa
                                    (a.».OBCPOrEOe)7
               NO
                        2. Evaluation Of Risk, Hazard And
                                  ARARa
                     For EaOi COPC. Is Individual Risk <10* and
                      kxtvktual Hazard <1 and Expo«jra PoM
                            Concentration YARAR7
                                                        NO
                                                                                       YES
                                                                          COPC Not finamd m a COC kr FS
                              COfC Mot MaatoMl n a OMnnl Of Cancam
                                        OCOQforFS

                                    «Mi|kM CMrwr Ao«ne.
                                        D8CP.EDB
                              Anaiyin Easnt
                                    1.4O>
                               tj
                                                                                            •.PCEandTCE









J. kamtfncatton of COPC Plumes
(See. 2.1 end 12}
hi»RT7
(Figures A-1 to A-38 1> Appenda A
Of RIReporQ

i
• HO
eOPC Not AaBkied as a COC for FS.
Ho Eniusoon of Remedial AfamttM


YES.





4-EvaluatJooofN
RamexflaJAI
Does Combination of U
Conctnirtfion*
KuniekMrap ja>nD PM^ 1

]
No Evaluation Of Aa

lead to Dereeap
•ffutlnu
•r Mass. Sort ATM)
c Eattntano
ConcenBnon to
iapSampengorey

YES


NO



C
U
BCftaW)


1 Evaluate Remedial Altamatlvaa In FS for
f4aaiPajmeReoion.
E*St 8*aa) Pkara) Ragion

| 1
» ;
OCsgemredtaT COCs Seieatd It
MI Phme Region: East Base Pune Re






x
tan:
I
    Beta 6


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