PB97-964505
                                EPA/541/R-97/043
                                November 1997
EPA Superfund
      Record of Decision:
       Lawrence Livermore Laboratory
       (USDOE) Operable Unit 1,
       Livermore, CA
       1/29/1997

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                              UCRL-AR-124061
   Final Record of Decision for the
General Services Area Operable Unit
    Lawrence Livermore National
         Laboratory Site 300
            January 1997
      Environmental Protection Department
      Environmental Restoration Program and Division

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Work performed  under  the  auspices of  the U. S. Department of Energy  by Lawrence  Livermore
National  Laboratory  under  Contract  \V-7405-Eng-48.

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UCRL-AR-124061           Final ROD for the GSA Operable Unit, Site 300              January 1997


                            Table of Contents
1. Declaration	1-1
    1.1.  Site Name and Location	1-1
    1.2.  Statement of Basis and Purpose	1-1
    1.3.  Assessment of the Site	1-1
    1.4.  Description of the Selected Remedy	1-1
    1.5.  Statutory Determinations	.%	1-2
    1.6.  Acceptance of the Record of Decision by Signatory Parties	1-3
2. Decision Summary	2-1
    2.1.  Site Name, Location, and Description	2-1
    2.2.  Site History and Summary of Enforcement	2-1
    2.3.  Highlights of Community Participation	2-2
    2.4.  Scope and Role of the GSA OU	2-2
    2.5.  Site Characteristics	2-3
          2.5.1. Chemical Releases	2-3
          2.5.2. VOCs in Ground Water	2-4
          2.5.3. VOCs in Soil/Rock	2-5
          2.5.4. VOCs in Soil Vapor	2-6
    2.6.  Risk Assessment	2-6
          2.6.1. Identification of Chemicals of Potential Concern	2-7
          2.6.2. Identification of Contaminated Environmental Media	2-7
          2.6.3. Estimates of Potential Exposure-Point Concentrations	2-7
          2.6.4. Human Exposure and Dose Assessments	2-8
          2.6.5. Toxicity Assessment	2-9
          2.6.6. Risk Characterization	,	2-10
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UCRL-AR-124061            Final ROD for the GSA Operable Unit, Site 300              January 1997

          2.6.7. Summary of Human Health Baseline Risks and Hazards
                Associated with Contaminants	2-11
          2.6.8. Summary of the Baseline Ecological Assessment	2-14
    2.7. Description of Remedial Action Alternatives	2-14
          2.7.1. Alternative 1—No Action	2-15
          2.7.2. Alternative 2—Exposure Control	2-15
          2.7.3. Alternative 3—Source Mass Removal and Ground Water Plume
                Control	2-16
    2.8. Summary of Comparative Analysis of Alternatives	2-17
          2.8.1. Overall Protection of Human Health and the Environment	2-18
          2.8.2. Compliance with ARARs	2-18
          2.8.3. Short-Term Effectiveness	2-19
          2.8.4. Long-Term Effectiveness  and Permanence	2-19
          2.8.5. Reduction of Contaminant Toxicity, Mobility, or Volume	2-20
          2.8.6. Implementability	2-20
          2.8.7. Cost Effectiveness	2-20
          2.8.8. State Acceptance	2-21
          2.8.9. Community Acceptance	2-22
    2.9. Selected Remedy	2-22
          2.9.1. Cleanup Goals	2-22
          2.9.2. Treatment System Design	2-23
          2.9.3. Performance Evaluations	2-32
          2.9.4. Innovative Technologies	2-35
          2.9.5. Reporting	2-36
          2.9.6. Summary of Preliminary Cost Estimates	2-36
    2.10.  ARARs	2-36
          2.10.1. Chemical-Specific ARARs	'.	2-37
          2.10.2. Location-Specific ARARs	2-39

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VCRL-AR-124061            Final ROD for the GSA Operable Unit. Site 300              January 1997

          2.10.3.  Action-Specific ARARs	2-39
          2.10.4.  Other Applicable Standards	2-40
    2.11.  Statutory Determinations	2-40
          2.11.1.  Overall Protection of Human Health and the Environment	2-40
          2.11.2.  Compliance with ARARs	2-41
          2.11.3.  Short-Term Effectiveness	2-41
          2.11.4.  Long-Term Effectiveness and Utilization of Permanent
                  Solutions	2-41
          2.11.5.  Reduction of Contaminant Toxicity, Mobility, or Volume as a
                  Principal Element	2-41
          2.11.6.  Implementability	2-42
          2.11.7.  Cost Effectiveness	2-42
          2.11.8.  State Acceptance	2-42
          2.11.9.  Community Acceptance	;	2-42
3.  Responsiveness Summary	3-1
    3.1.   Organization of the Responsiveness Summary	3-1
    3.2.   Summary of Public Comments and Responses	3-1
          3.2.1. Selected Remedial Action	3-1
          3.2.2. General Comments	3-13
References	R-l
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UCRLAR-124061            Final ROD for the GSA Operable Unit, Site 300             January 1997
                               List of Figures

Figure 1.  Location of LLNL Livermore Site and Site 300.
Figure 2.  Location of the General Services Area operable unit at Site 300.
Figure 3.  Conceptual hydrogeologic model of the General Services Area.
Figure 4.  Confirmed chemical release sites in the central GSA.
Figure 5.  Confirmed chemical release sites in the eastern GSA.
Figure 6.  TCE concentrations in ground water from the shallow aquifer
           (Qt-Tnsci) in the central GSA (4th quarter 1995 data).
Figure 7.  TCE concentrations in ground water from the Tnbs i regional aquifer
          in the central GSA (4th quarter 1995 data).
Figure 8.  Total VOC concentrations in ground water in the alluvium (Qal) and
          shallow bedrock (Tnbsi) in the eastern GSA (4th quarter 1995 data).
Figure 9.  TCE concentrations in ground water from the deeper Tnbsi regional
          aquifer in the eastern GSA (4th quarter 1995 data).
Figure 10. Locations of active water-supply wells.
Figure 11. Locations of existing and proposed ground water extraction and
          reinjection wells, soil vapor extraction wells and treatment systems.
Figure 12. Total VOC concentrations in ground water in the alluvium (Qal) and
          shallow bedrock (TnbS]) in the eastern GSA (4th quarter 1991 data).
Figure 13. TCE concentrations in ground water from the deeper Tnbs! regional
          aquifer in the eastern GSA (4th quarter 1991 data).
Figure 14. Schematic of the eastern GSA remediation system for the selected
          remedy (Alternative 3b).
Figure 15. TCE concentrations in ground water from the shallow aquifer (Qt-
          Tnsc,) in the central GSA (3rd quarter 1992 data).
Figure 16. TCE concentrations in ground water from the Tnbsj regional aquifer
          in the central GSA (4th quarter 1991 data).
Figure 17. Schematic of the central GSA remediation system for the selected
          remedy (Alternative 3b).
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UCRL-AR-I24061
Final ROD for the GSA Operable Unit, Site 300
January 1997
                               List of Tables

Table 1.   Contaminants of potential concern in ground water in the GSA.
Table 2.   Contaminants of potential concern in surface soil (<0.5 ft) in the GSA.
Table 3.   Contaminants of potential concern in subsurface soil (>0.5-12.0 ft) in the GSA.
Table 4.   Contaminants of potential concern in VOC soil flux in the GSA.
Table 5.   Summary of the fate and transport models applied to estimate human
          exposure-point concentrations in the GSA OU.
Table 6.   Cancer risk and hazard index summary, and reference list for the
          GSA OU.
Table 7.   Summary of GSA OU remedial alternatives.
Table 8.   Comparative evaluation of remedial alternatives for the GSA OU.
Table 9.   Chemical-specific ARARs for potential chemicals of concern in
          ground water at the GSA OU.
Table 10.  Selected remedy (Alternative 3b):  Capital costs for source mass
          removal and plume migration prevention in the GSA OU.
Table 11.  ARARs for the selected remedy at the GSA OU.
Acronyms and Abbreviations
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UCRL-AR-124061          Final ROD for the GSA Operable Unit, Site 300            January 1997
               Acronyms and Abbreviations

   For the convenience of the reader, a reference list defining acronyms and abbreviations used
throughout this document is presented after the Tables.
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UCRL-AR-124061           Final ROD for the GSA Operable Unit. Site 300             January 1997
                             1. Declaration


1.1.  Site Name and Location

   The site described in this Record of Decision (ROD) is known as the General Services Area
(GSA) operable unit (OU) located at Lawrence Livermore National Laboratory (LLNL) Site 300,
Tracy, California.  This OU is designated as OU-1 in the Site 300 Federal Facility Agreement
(FFA) signed in June 1992.

1.2.  Statement of Basis and Purpose

   This decision document presents the selected remedial action for the GSA OU at LLNL
Site 300.  This  remedial action  was developed in accordance with  the Comprehensive
Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by
the Superfund  Amendments and Reauthorization Act  of  1986 (SARA) and, to the extent
practicable, the National Contingency Plan (NCP). This decision is based on the Administrative
Record for this OU. The State of California Department of Toxic Substances Control (DTSC),
Central  Valley Regional  Water Quality Control Board  (CVRWQCB), and the U.S.
Environmental Protection Agency (EPA) Region DC concur with the selected remedy.

1.3.  Assessment of the Site

   Based on the baseline risk assessment, actual or threatened releases of hazardous substances
at  this OU, if not addressed by implementing the response actions selected in this ROD,  may
present  an  imminent  and substantial endangerment to public health  and welfare, or the
environment.

1.4.  Description of the Selected Remedy

   In June 1992, a FFA for the LLNL Site 300 Experimental Test Facility was signed by the
regulatory agencies (U.S. EPA Region IX, DTSC, CVRWQCB)  and the landowner (U.S.
Department of Energy [DOE]). The FFA defines seven OUs and designates the GSA OU as
OU-1. The GSA OU is located in the southeastern portion of Site 300 and was established to
address  soil and ground water contamination in the subsurface immediately beneath and
approximately 2,300 ft downgradient of the  GSA facilities.  Currently, a stream-lined CERCLA
process is being adopted for Site 300 cleanup. This process will not affect the GSA OU, which
will proceed on the current FFA schedule.
   Remedial actions for the GSA OU primarily target trichloroethylene (TCE) and other volatile
organic compounds (VOCs) in ground water and soil beneath the GSA.  The risks associated
with subsurface contamination at the GSA OU  are: 1) potential ingestion of ground water
containing VOCs, and 2) onsite worker inhalation exposure to TCE volatilizing from subsurface
soil (0.5-12.0 ft) to indoor air within Building 875.
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UCRL-AR-124061            Final ROD for the GSA Operable Unit. Site 300              January 1997


   Three remedial alternatives for the GSA OU were presented in the Final General Services
Area Feasibility Study (Rueth and Berry, 1995).  These remedial alternatives were evaluated by
the supervising Federal and State regulatory agencies and presented to the public.  DOE and the
regulatory agencies, the U.S. EPA, and the State of California DTSC and CVRWQCB  agreed
that Alternative 3b provides the most effective means of remediating VOCs in soil  and  ground
water to levels protective of human health and the environment. Alternative 3b is presented as
the selected remedy for the GSA OU. The major components of the selected remedy include:
   •   Monitoring throughout the predicted 55 years of remediation, plus five years of post-
       remediation monitoring.
   •   Contingency point-of-use (POU) treatment for existing offsite water-supply wells.
   •   Administrative controls to prevent human exposure by restricting access to or  activities in
       contaminated areas, if necessary.
   •   Soil vapor extraction (SVE) and treatment in the central GSA dry well source area. SVE
       will be conducted to: 1) reduce VOC concentrations in soil vapor to levels protective of
       ground water, 2) remediate dense non-aqueous phase liquids (DNAPLs) in the soil, and
       3) mitigate VOC inhalation risk inside Building 875.
   •   Dewatering of the shallow water-bearing zone in the  vicinity of the Building 875 dry well
       release area to enhance the effectiveness of SVE by exposing a larger soil volume to
       vapor flow.
   •   Extraction and treatment  of ground water in the GSA  until  drinking water standards
       (Maximum Contaminant Levels, or MCLs) are reached in both the regional and shallow
       aquifers.  Modeling indicates ground water extraction will reduce ground water VOC
       concentrations in the eastern and central GSA to the remediation goal (MCLs) within 10
       and 55 years, respectively.
   The 1995 present-worth cost of the selected remedy is estimated to be approximately  $18.90
million. This estimate assumes:  1) 10 years of SVE, and 55 years of ground water extraction in
the central GSA, 2) 10 years of ground water extraction in the eastern GSA debris burial trench
area, and 3) 60 years of ground water monitoring.  These time and cost estimates do not  include
the development, testing, or utilization of any future innovative technologies, which, if available,
could be used to expedite cleanup and/or reduce long-term costs.
   DOE and the regulatory  agencies will jointly determine the scope and  schedule of all
required post-ROD documents and reports (up to the Final Remedial Design document),  as well
as schedules for implementing the selected remedy.

1.5.  Statutory Determinations

   The selected GSA remedial action is protective of human health and the  environment and
complies with Federal and State applicable or relevant and appropriate requirements (ARARs).
The selected remedy provides both short- and long-term effectiveness in meeting ARARs and
protecting human health and the environment. This remedy satisfies the statutory  preference for
remedies that employ treatment technologies that reduce contaminant toxicity, mobility, or
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UCRL-AR- 124061               Final ROD for the GSA Operable Unit, Site 300           January 1997


volume as a principal element. The remedial  action is readily implementable and provides the
most cost-effective means of remediating VOCs in the affected media available at this time.

   The supervising Federal and State regulatory agencies participated in the evaluation of the
proposed  remedial alternatives and  concur  with the selected remedy.  Public input  was
considered and used, as appropriate,  in the selection and development of the final remedial
action.

   A review will be conducted within five years and every five years after commencement of
the remedial action to ensure that the remedy continues to provide adequate protection of human
health and the environment.

1.6.  Acceptance of the Record of Decision by Signatory Parties

   Each undersigned representative of a party certifies that he or she is fully authorized to enter
into the terms and conditions of this agreement and to legally bind such party to this agreement.

   IT IS SO AGREED:
   Daniel D. Opalski                Date
   Chief, Federal Facilities Cleanup  Branch
   Superfund Division
   U.S. Environmental Protection Agency
   Region IX
   Barbara Cook, P.E\J               Date
   Chief, Northern California Coastal Cleanup Operations Branch
   California Department of Toxic Substances Control


                                       "2-/S/T7
   Jam :s R. Bennett                   Date
   Interim Executive Officer
   Slate of California Regional Water Quality Control Board
   Central Vallev-R-eeion
   fames M. Turner, Ph.D.             Date
   Manager
   Oakland Operations Office
   U.S. Department of Energy
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UCRL-AR-124061               Final ROD for the GSA Operable Unit, Site 300            January 1997
                        2.  Decision Summary


2.1.  Site Name, Location, and Description

   Site 300, a DOE-owned experimental test facility operated by the University of California, is
located in the southeastern Altamont Hills of the Diablo Range,  about 17 mi east-southeast of
Livermore and 8.5 mi southwest of Tracy, California (Fig.  1).  The site is bordered by cattle
grazing land, a California Department of Fish and Game ecological preserve, an outdoor
recreational facility, and a privately owned high explosives (HE) testing facility. For the purpose
of this ROD, it is assumed that Site 300 will remain under the continued control of DOE for the
foreseeable future.
   The GSA OU is located in the southeastern part of Site 300, and was established to address
soil and ground water contamination in the  subsurface below the OU (Fig. 2).

2.2.  Site History and Summary of Enforcement

   Prior to the purchase of Site 300 land for development as  a DOE experimental test facility in
1953, the GSA was used for cattle ranching and livestock grazing.  Since the late 1950s, the GSA
facilities have been used as administration offices and equipment fabrication and repair shops
that support Site 300 activities.  Site 300 was in operation prior to the enactment of the Resource
Conservation and Recovery Act of 1976.
   Undetermined quantities of solvents containing TCE, a  suspected human carcinogen, and
other VOCs were released to the ground as  a result of past activities in the craft shops, equipment
fabrication and repair facilities in the GSA, and are in the soil/rock and ground water in the area.
Other chemical compounds commonly detected in soil/rock and ground water in the GSA
include tetrachloroethylene (PCE), 1,2-dichloroethylene (DCE), 1,1-DCE, and freon compounds.
   In  1982, DOE discovered contamination at the site and began an  investigation  under
CVRWQCB guidance.  All investigations  of potential chemical contamination at Site 300 were
conducted under the oversight of the CVRWQCB until August 1990, when Site 300 was placed
on the National Priorities List.  Since then, all  investigations have  been conducted in accordance
with CERCLA  under the guidance of three supervising regulatory agencies:  the U.S. EPA
Region IX, the CVRWQCB, and the DTSC. The DOE entered into a FFA with these agencies in
June 1992.
   In accordance with CERCLA requirements and the terms of the Site 300 FFA, DOE released
the Final  Site-Wide Remedial Investigation (SWRI) report (Webster-Scholten, 1994), the Final
General Services Area Operable Unit Feasibility Study (FS) (Rueth and Berry, 1995) and the
Proposed Plan  for Remediation of the Lawrence Livermore National Laboratory Site 300
General Services Area (U.S.  DOE/LLNL,  1996).  The SWRI documented  environmental
investigations that occurred at Site 300 since 1982, and characterized the extent of VOCs in the
subsurface and the Site  300 hydrogeology. The GSA FS developed and evaluated alternatives
for remedial  action at the GSA.  The SWRI and the FS form the basis for selecting technologies
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UCRL-AR-J2406J            Final ROD for the GSA Operable Unit. Site 300             January 1997


to remediate the GSA OU. The Proposed Plan for remediation of the GSA OU summarized site
conditions and remedial alternatives, and presented the preferred remedy.
   CERCLA Removal Actions were initiated in the eastern and central GSA in 1991 and 1993,
respectively. To date, 35,387 grams (79 Ib) of VOCs have been removed from the GSA through
ground water and soil vapor extraction as part of these Removal Actions.

2.3.  Highlights of Community Participation

   The SWRI and the FS for the GSA OU were made available to the public in April 1994 and
October 1995, respectively. The Proposed Plan was released to the public in March 1996. This
ROD presents the selected remedial action for the GSA OU. All documents were prepared in
compliance with CERCLA as amended by  SARA. The decision for this site is based on the
Administrative Record, which is available at the Information Repository at the LLNL Visitors
Center and the Tracy Public Library.
   A public review and comment period on the preferred remedial alternative began April 10,
1996,  and ended May 10, 1996.  Interested members of the public were invited to review all
documents and  comment on the considered remedial alternatives by writing to the Site 300
Remedial Project Manager or by attending a public meeting on April 24,  1996, at the Tracy Inn
in Tracy,  California. At this meeting, representatives from DOE, University of California,
U.S. EPA, and the State of California discussed the proposed remediation plan and addressed
public  concerns and questions.  Questions  and comments from the public are presented and
addressed in the Responsiveness Summary of this ROD.

2.4.  Scope and Role of the GSA OU

   The Site 300 FFA defines the following seven OUs at Site 300:
   •   OU-l.GSA.
   •   OU-2, Building 834.
   •   OU-3, Pit 6.
   •   OU-4, HE Process Area Building 815.
   •   OU-5, Building 850/Pits 3 and 5.
   •   OU-6, Building 854.
   •   OU-7, Building 832 Canyon.
   •   OU-8, Site 300 Monitoring.
   Investigations at the GSA OU address VOCs in soil/rock and ground water released to the
environment as a result of past activities in the GSA craft shops, and equipment fabrication and
repair  facilities. The principal potential threats  to human  health and the environment are:
1) ingestion of VOCs in ground water, and 2) exposure to VOC vapors volatilizing from shallow
soil into Building 875.
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VCRL-AR-124061            Final ROD for the GSA Operable Unit. Site 300             January 1997

   This ROD addresses both the potential human health ingestion risk posed by VOCs in ground
water, as well as the inhalation risk posed by VOCs in the vadose zone at the GSA OU. The
purpose of the selected remedy is to protect human health and the environment by reducing VOC
concentrations in soil vapor and ground water and controlling VOC migration.

2.5.  Site Characteristics

   Since environmental investigations began at the GSA in 1982, 75 exploratory boreholes have
been drilled and 98 ground water monitor wells have been completed.  Details of the geology
and hydrogeology of the GSA OU, as well as environmental investigations conducted in this OU
are presented in Chapter 14 of the Site 300 SWRI. Three water-bearing zones or hydrogeologic
units have been identified (Fig. 3):
   •  Qt-Tnscj Hydrogeologic Unit:  .This  shallow water-bearing zone occurs beneath the
      central GSA portion  of the OU and  is composed of stratigraphic units Qt (terrace
      alluvium), Tnbs2 (Neroly Formation-Upper Blue Sandstone),  and Tnsci  (Neroly
      Formation-Siltstone/Claystone).    Depending  on topography,  depth  to water is
      approximately 10 to 20 ft beneath the ground surface.  As a result of past releases, this
      shallow aquifer contains TCE and other VOCs. The VOC plume in this shallow aquifer
      is separated from the regional aquifer by a 60- to 80-ft thick aquitard (Tnsci) in most of
      the central GSA. Ground water data indicate that the VOC plume in the shallow aquifer
      has not affected the regional aquifer in this area. Ground water in this shallow aquifer
      flows south-southeast with  an estimated flow velocity of 0.09 to 3 ft/day.
   •  Tnbsj Hydrogeologic Unit (Regional Aquifer): The regional aquifer occurs in the lower
      Neroly Formation  (Tnbsj). This aquifer is encountered 35 to 145 ft below the ground
      surface under confined to semi-confined conditions in the central GSA. Ground water
      flow in this unit is to the south-southeast at a flow velocity of 0.3 ft/day.
   •  Qal-Tmss Hydrogeologic Unit:  This hydrogeologic unit is composed of the stratigraphic
      units: Qal (alluvium), Tnscj, Tnbsj, and Tmss (Cierbo Formation). For the most part, the
      Tnsci aquitard is absent in the eastern GSA, and the shallow water-bearing zone (Qal) is
      in hydraulic communication with the underlying regional aquifer (Tnbsi).  As a result,
      some contamination has migrated downward from  the shallow-water bearing zone into
      the regional  aquifer.   Ground water flow in the  alluvium (Qal)  and shallow Tnbsi
      bedrock  is eastward, turning north to follow the trend of the valley. Although  the flow
      velocity  is dependent on local hydraulic conductivity, the maximum flow  velocity is
      estimated to be about 200 to 1,200 ft/yr.

2.5.1.  Chemical Releases
   Historical information  and analytical data suggest that VOCs, in the dissolved form and/or as
DNAPLs, were  released  to  the ground  in wastewater from the craft and repair shops, as
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UCRL-AR-J2406J               Final ROD for the GSA Operable Unit, Site 300            January 1997


leaks/spills from solvent storage tanks or drums, and associated with debris buried in trenches in
the eastern GSA in the 1960s and 1970s. These releases include:
   •   VOCs in rinse-, process-, and wash-water discharged to four dry wells from the central
       GSA craft and repair shops.  Based on soil and ground water analytical data, the greatest
       VOC mass is concentrated in the vicinity of the Building 875 former dry wells.
   •   VOCs  released to the  ground  from a decommissioned drum storage rack  north  of
       Building 875.
   •   VOCs in rinse water discharged from a steam cleaning/sink area east of Building 879.
   •   VOCs associated with craft shop debris buried in trenches in the eastern GSA.
   The confirmed release sites for the  central and eastern GSA are shown in Figures 4 and 5.
The quantity of TCE released in these areas greatly exceeds that of other VOCs.

2.5.2. VOCs in Ground Water

   TCE is the most prevalent VOC in ground water, typically comprising 85 to 95% of the total
VOCs detected. Other VOCs that have been detected include PCE, 1,2-DCE, 1,1-DCE, 1,1,1-
trichloroethane, acetone, benzene, bromodichloromethane, chloroform, ethylbenzene, Freon 113,
toluene, and xylenes (total isomers) (Table 1).
   Detected concentrations  of ethylbenzene, toluene, and  xylene have decreased over time.
Toluene, ethylbenzene, and xylenes have not been detected in ground water from any GSA wells
in over 2.5 years.  The last detections of these compounds occurred in 1994 when toluene was
detected in well W-875-02 at a concentration of 0.5 u,g/L and xylene was detected in well W-7N
at a concentration of 0.96 u,g/L. No toluene, ethylbenzene, or xylenes have been detected in any
other GSA wells for  3.5 years or more.  Therefore, these constituents  are no longer considered
contaminants of concern. The CVRWQCB believes that it is appropriate to continue to monitor
for these constituents, but at a reduced  frequency. The extent and frequency of monitoring for
these constituents will be addressed in the Remedial Design document.
   The highest ground water VOC concentrations in the central GSA have been detected in the
vicinity of former dry well pad south of Building 875 (Figs. 4 and 6). TCE has been detected in
ground water in concentrations up to 240,000 micrograms per liter (u\g/L) in a bailed ground
water sample collected from well W-875-07 in March 1993. This concentration  suggests that
TCE is present as residual DNAPL in the  subsurface.  As of third quarter 1994, the maximum
TCE concentration in ground water samples collected from the Building 875 dry well pad area
was  10,000 jig/L in well W-7I (Fig. 6).  In general, if a ground water VOC concentration is 1 to
10% of the solubility of that VOC in ground water, a DNAPL may be present.  Because the
aqueous solubility of TCE is 1,100,000 jig/L, TCE concentrations in the  range of  11,000 to
110,000 Hg/L or greater may indicate DNAPL. The only wells in the GSA where ground water
sample data indicate  the possible presence  of DNAPLs (TCE concentrations > 11,000  u.g/L) are
wells W-875-07,  -08, -09, -10, -11,  -15, and W-7I.  As shown in Figure 6, these wells are all
located in  the Building 875 dry well pad area in the central GSA. The source of DNAPLs in this
area was the waste water disposed in the two former dry wells, 875-S1 and 875-S2, located south
of Building 875 (Fig. 4). Based on soil sample data from boreholes drilled prior to installation of
the dry well pad wells, the bulk of TCE contamination in the dry well pad area is concentrated at
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UCRL-AR-124061           Final ROD for the GSA Operable Unit, Site 300              January 1997


a depth of 20 to 35 ft near the contact between the Tnb$2 water-bearing zone and the underlying
Tnsci confining layer. These data support a DNAPL-type scenario where TCE, which is denser
than water, would tend to sink to the lowest point possible in a water-bearing unit, such as the
contact between the water-bearing zone and an underlying confining layer that prevents the
further downward migration of contaminants.
   No other wells in the GSA have  contained VOCs in  ground water in concentrations
indicative of DNAPLs, including wells  located at other source areas and the two wells (W-7F
and W-875-03) located within 50 to 75 ft of the dry well pad.  We have therefore concluded that
the DNAPLs are confined to the Building 875 dry well pad area in the central GSA.
   As shown in Figure 6, a VOC ground water plume in the Qt-Tnscj shallow aquifer extends
from the Building 875 dry well pad and Building 872 and Building 873 dry wells into the Corral
Hollow Creek alluvium. There is a smaller ground water plume with significantly lower VOC
concentrations to the north associated with the  drum storage  rack and steam cleaning release
sites.  Based on ground water data collected from the Tnbsj regional aquifer, the VOC plumes
appear to be confined to the Qt-Tnscj hydrogeologic unit in this area, where the Tnsci confining
layer prevents the downward migration  of contaminants.  West of the sewage treatment pond,
TCE has been detected in ground water in the regional aquifer (Fig. 7) where the Tnsci confining
layer is absent.  The low TCE concentrations have generally been decreasing in the regional
aquifer in this area since 1990.
   In the eastern GSA, the highest VOC concentrations in ground water occur in the vicinity of
the debris burial trench area (Fig. 8). TCE has been detected in ground water in concentrations
up to 74 ^ig/L in this area. A VOC ground water plume extends eastward from the debris burial
trench area and has migrated northward in the Corral Hollow alluvium. The plume with total
VOC concentrations exceeding 5 \ig/L currently extends approximately 550 ft from the debris
burial trench release area. TCE has also been detected at low concentrations in ground water in
the regional aquifer in the vicinity of the debris burial trenches (Fig. 9). TCE in the regional
aquifer in this area is generally limited to portions of the regional aquifer which directly underlie
the contaminated shallow water-bearing zone. The maximum VOC concentrations in ground
water as of fourth quarter 1995 were 20  |J.g/L in  the shallow water-bearing zone and 19 p.g/L in
the regional aquifer.
   Further details  on the extent of VOCs  in ground  water in  the GSA can  be  found in
Section 14-4.5, Chapter 14 of the Site 300 SWRI (Webster-Scholten, 1994), and Section 1.4.7 of
the GSA FS (Rueth and Berry, 1995).

2.5.3. VOCs in Soil/Rock

   The highest TCE concentrations in soil/rock  (up to 360 milligrams per kilogram [mg/kg]) in
the central GSA were detected in the vicinity of the Building 875 former dry wells 875-S1 and
875-S2 at a depth of 20 to 35 ft near the contact between the Tnbs2 water-bearing zone and the
underlying Tnscj confining layer.  Also, low concentrations of VOCs were detected in soil/rock
samples collected from boreholes in the  vicinity of the other four confirmed release sites in the
central GSA:  the  decommissioned solvent drum rack, dry wells  872-S and 873-S, and the
Building 879 steam-cleaning facility. VOC concentrations ranged from 0.0002 mg/kg to 0.9
mg/kg in these samples collected in  1989.
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   TCE, PCE and 1,2-DCE have been detected in concentrations up to 0.19 mg/kg in borehole
soil samples collected in 1989 in the vicinity of the debris burial trenches in the eastern GSA.
   Further details on the extent of VOCs in soil/rock in the GSA are described in Section 14-4.3,
Chapter 14 of the Site  300 SWRI (Webster-Scholten, 1994) and Section  1.4.6 of the GSA FS
(Rueth and Berry, 1995).

2.5.4. VOCs in Soil Vapor

   Extensive soil vapor surveys, including both active and passive techniques, were conducted
between 1988 and 1994 to:  1) assist in the identification of release sites, 2) determine the extent
of VOC contamination, and 3) monitor the progress of soil vapor remediation efforts.
   Further  details  on  the extent  of  VOCs in soil  vapor  in the  GSA can  be found  in
Section 14-4.2, Chapter 14 of the Site 300 SWRI (Webster-Scholten, 1994), and Section 1.4.3 of
the GSA FS (Rueth and Berry, 1995).

2.6.  Risk Assessment

   The baseline risk assessment provides the basis for taking action and identifies the potential
exposure pathways that need to be addressed by the remedial action. It serves as the baseline to
indicate what potential  risks might exist if no action were taken at the  site. This section of the
ROD reports the results of the  baseline risk assessment conducted for this site.  Additional details
may be found in Chapter 6 of the Site 300 SWRI  (Webster-Scholten, 1994), and Section 1.6 of
the GSA FS (Rueth and Berry, 1995).
   The baseline risk assessment evaluated potential present and future public health and
ecological risks associated with  environmental  contamination in the GSA OU, using the
assumption that no cleanup or remediation activities would take place at the site.  Selection of a
specific remediation strategy is based in part on the extent to which it can reduce potential public
health and ecological risks.
   The baseline risk assessment presented in the SWRI consists of six components:
   •   Identification of chemicals of potential concern.
   •   Identification of the contaminated environmental media.
   •   Estimation of potential exposure-point concentrations of contaminants.
   •   Human exposure and dose assessment.
   •   Toxicity assessment.
   •   Risk characterization.
Each of these components are summarized in the following sections. Additional details are
available in the Site  300 SWRI and in the GSA FS.
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2.6.1. Identification of Chemicals of Potential Concern

   Tables 1 through 4 present the chemicals of potential concern identified in the GSA OU.
Details of the methodology used to identify these contaminants are described in the Site 300
SWRI (Webster-Scholten, 1994).

2.6.2. Identification of Contaminated Environmental Media

   Based on the assessment of the nature and extent of contamination obtained  during site
characterization, contaminants of potential concern were identified in different environmental
media in the GSA  OU:  ground water, surface soil, subsurface soil, and soil vapor (Tables 1
through 4, respectively). The 95% upper confidence limit (UCL) of the mean concentration and
exposure-point concentrations of each contaminant are listed in Table 5.

2.6.3. Estimates of Potential Exposure-Point Concentrations

   Conceptual models were developed to identify the probable migration processes and routes
of the chemicals of concern from release sites and source media  in the GSA OU  to selected
potential exposure points.  The  conceptual models provided the basis for  selection of the
quantitative models  used  to generate estimates of contaminant  release rates and  potential
exposure-point concentrations. The exposure-point concentrations were used to estimate the
magnitude of potential exposure to contaminants in the baseline risk assessment.  The release
areas, migration processes, and exposure points identified in the GSA OU are given in Table 5.
In addition, this table lists the mathematical models used to estimate contaminant migration rates
and the  calculated exposure-point  concentrations for the  chemicals of concern  in each
environmental medium.
   Direct measurements of VOC soil flux were obtained in the GSA that  were used in a
mathematical model to estimate exposure-point  concentrations of contaminants  in the
atmosphere  when  VOCs volatilize from subsurface  soil in the  vicinity of three exposure
locations in  the GSA OU:   1) the Building 875 dry  well area, 2) the central GSA, and 3) the
eastern GSA.  A mathematical model was applied, using subsurface soil (0.5 to 12.0ft) VOC
concentrations in the vicinity of the Building 875 dry well pad, to estimate the  potential
exposure-point concentrations of contaminants in  indoor air of Building 875 when VOCs
volatilize from subsurface soil  underneath  the building and  diffuse into the building.
Measurements of actual VOC concentrations inside Building 875 were not conducted or used in
the estimate of exposure-point concentrations in indoor air as the work activities  which still
occur in  Building  875 involve the use of VOC-containing solvents.  Therefore,  it would  be
difficult,  if not impossible to distinguish between VOC vapors migrating from the subsurface
through the concrete floor and those present in indoor air as a result of current work  activities
utilizing solvents.   As a result, we took a health conservative approach and utilized  soil sample
data from the Building 875 dry well  pad approximately 35 ft from the building to calculate
exposure-point concentrations inside Building 875.
   In addition, estimates were made of the concentrations of surface soil (< 0.5 ft) contaminants
that are bound to  resuspended particles throughout the OU.  The 95% UCLs of the mean
contaminant  concentration in  the surface  soil, and site-specific  data on total resuspended
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participates were used to estimate the concentration of surface  soil contaminants bound to
resuspended particles throughout the OU. For direct dermal contact and incidental ingestion, the
exposure-point concentrations of contaminants in surface soil are the same as the 95% UCLs of
the mean concentration of the chemicals.
    The fate and transport of VOCs in ground water were considered for both the central and
eastern GSA,  as well as a combined central and eastern GSA plume.  For the central GSA,
exposure-point concentrations were estimated at the site boundary  and then modeling was used
to estimate exposure-point concentrations at the California Department of Forestry water-supply
well, CDF-1, located approximately 300 ft southeast of the Site 300 boundary. For the eastern
GSA, exposure-point concentrations were estimated for a theoretical well at the site boundary
and for two plumes commingling at well CDF-1; these concentrations were modeled  to
downgradient water-supply well SR-1 (Fig. 10).

2.6.4. Human Exposure and Dose Assessments

    Exposure scenarios and pathway exposure factors (PEFs) used to assess the magnitude of
potential human exposure and dose are described below.

2.6.4.1. Exposure Scenarios

    The exposure scenarios used to evaluate potential adverse health effects associated with
environmental contamination in the GSA OU were developed based  on assumptions about
present and future uses of the site and lands in the immediate vicinity.
    Two principal  scenarios  were developed  to evaluate potential  human exposure  to
environmental contaminants in the GSA OU. The first of these  scenarios pertains to adults
working in the  GSA OU.  This  scenario addresses potential health risks attributable  to
contaminants in subsurface soil and surface soil, where an adult on site (AOS) is presumed to
work in the immediate vicinity of the contamination over their entire period of employment at
the site (25 years).  Subsurface soil contaminants can  volatilize into air, where they may  be
inhaled by individuals who work in the vicinity of the contamination. Surface soil contaminants
bound to resuspended soil particulates may also be inhaled by individuals in the course of work-
related activities at the site. In addition, we evaluated AOS exposure as a consequence of dermal
absorption and incidental ingestion of contaminants on surface soil.
    The second scenario pertains to residential exposures (RES), which are associated with use of
contaminated  ground water from:  1) theoretical wells installed at  the central and eastern GSA
site boundaries, 2) well CDF-1, and 3) well SR-1. The identification and selection of exposure
pathways related to  residential use of contaminated ground water were based on the assumption
that well water will be used to supply all domestic water needs, such as those associated with
showering or bathing, cooking, dishwashing, and laundry.  We also assumed that contaminated
ground water will be used to irrigate home gardens, and will be supplied to dairy and beef cattle
raised for domestic  consumption.  Accordingly, we evaluated potential  residential exposure to
contaminants  in  ground water at theoretical wells and existing wells CDF-1 and SR-1  due to:
1) direct ingestion of water, 2) inhalation of VOCs that volatilize from water to indoor air,
3) dermal absorption of contaminants while showering or bathing, 4)  ingestion of  fruits and
vegetables grown using contaminated ground water, and 5) ingestion of meat and milk from
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homegrown beef and dairy cattle supplied with contaminated ground water. For the purpose of
the risk assessment, we assume residents could be exposed to contaminants in ground water for
30 years.

2.6.4.2.  Pathway Exposure Factors

   To estimate the magnitude of potential human exposure to contaminants in the GSA OU, we
developed PEFs, which convert the exposure-point concentrations of contaminants into estimates
of average contaminant intake over time (the chronic daily intake, or GDI).  These PEFs are
based on a series of reported and/or assumed parameters regarding current and potential  land use
patterns in and around the GSA OU, residential occupancy patterns,  and length of employment.
PEFs also account for a number of physiological and dietary factors such as the daily ingestion
rates of water and homegrown fruits, vegetables, beef, and milk; daily breathing rate; and surface
area of exposed skin.
   Reference documents for PEF data that were used to evaluate potential adult onsite and
residential exposure to contaminants and summary values are listed in Table 6.

2.6.5. Toxicity Assessment

   For each location with  environmental contamination,  we began by identifying those
chemicals of concern that are classified by the U.S. EPA (U.S. EPA, 1992a) or  by the State of
California EPA (1992) as carcinogens. This classification is based on data from epidemiological
studies, animal bioassays, and in vivo and in vitro tests of genotoxicity.

2.6.5.1.  Cancer Potency Factors

   The Cancer Potency Factors (CPFs) used in our estimations of cancer risk were obtained
from  values published in either the Integrated Risk Information  System (IRIS) (U.S. EPA,
1992b), the Health Effects Assessment Summary Tables (U.S. EPA,  1992a,c), or by the State of
California, EPA (1992). CPFs for TCE and PCE were also provided by Region IX of the U.S.
EPA (1993a).  All CPFs were derived using versions of the linearized, multistage dose-response
model (U.S. EPA, 1989a,b); generally, the dose- and tumor-incidence data used in the model are
from animal bioassays. For contaminants of potential concern at Site 300, the  exceptions are
cadmium, benzene, and beryllium,  where human tumor data are available. The model calculates
the potential increased cancer risk, where increased risk is linearly related to dose for low-dose
levels  typical of environmental exposure.  Use of  animal bioassay data to predict human
tumorigenic response assumes that  animals are appropriate  models of human carcinogenic
response, and that the dose-response relationships observed in high-dose animal bioassays can be
extrapolated linearly to  the low doses generally associated   with human exposure  to
environmental contaminants. When CPFs were available for a particular contaminant from both
a U.S. EPA source and the State of California, the highest potency values were used.
   Reference documents for CPFs (slope factors) used to calculate cancer risks in our evaluation
are listed in Table 6.
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2.6.5.2. Reference Dose

   The reference doses (RfDs) used to evaluate potential noncarcinogenic adverse health effects
were based, when possible, on long-term (i.e., chronic) exposures, and were derived by dividing
an experimentally-determined no-observed-adverse-effect-level or lowest-observed-adverse-
effect-level (each has units  of mg/[kg  • d]) by one or more uncertainty  factors (U.S. EPA,
1992a,b,c). Each of these uncertainty factors has a value that ranges from 1 to 10 (U.S. EPA,
1992a,b,c). Pathway-specific RfDs were used, when available (U.S. EPA, 1992a,b,c; Cal-EPA,
1992), to calculate a corresponding Hazard Quotient (HQ). If pathway-specific RfDs were not
available, the published RfDs (typically  developed for oral exposures) were used to calculate an
HQ for all exposure pathways.
   Reference documents and reference doses used to calculate noncancer hazard indices in our
evaluation are listed in Table  6.

2.6.6. Risk Characterization

   The risk assessment  was performed in accordance with Risk Assessment Guidance for
Superfund (U.S. EPA, 1989a,b). Carcinogenic risks, an evaluation of potential noncarcinogenic
exposure health hazards, and  the additivity of response are described below.

2.6.6.1. Carcinogen ic Risks

   For carcinogens, we calculated the potential incremental cancer risk associated with long-
term exposure to chemicals in surface soil, subsurface soil, and ground water. For each chemical
at each exposure  location,  the  total risk attributable to that  chemical was estimated by
multiplying each pathway-specific intake (e.g., the dose due to ingestion of water or to inhalation
of contaminants that volatilize from water to indoor air) by the corresponding pathway-specific
CPF.  The products of each pathway-specific intake and pathway-specific CPF were summed to
obtain the potential  incremental cancer risk for a specific chemical.  Parallel sets of calculations
were completed for all chemicals at each exposure location, then values of chemical-specific risk
from  all chemicals  were summed to  yield  an estimate of total incremental risk for exposures
associated with  a given location.

2.6.6.2. Evaluation of Hazard from Exposure to Chemicals that Cause
Noncancer Health Effects

   For chemicals  of potential concern that  are not classified as carcinogens, and for those
carcinogens known to cause  adverse health effects other than cancer, the potential for exposure
to result in noncarcinogenic  adverse health effects was evaluated by comparing the GDI with  a
RfD.  When calculated for a  single chemical, this comparison yields an HQ. For each chemical
at each location, pathway-specific HQs were  summed (where  applicable) to obtain an HQ
estimate for a given chemical. We then summed all HQs from all chemicals to yield a hazard
index (HI) estimate for exposures associated with a given location.
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2.6.6.3. Additivity of Response

    In every  location at or near the GSA OU where cancer risk and noncancer HQs were
calculated, GDIs were estimated for exposures attributable to multiple pathways for each of
several contaminants. As noted previously, the total potential cancer risk and/or total HI were
estimated by summing risk or HQs for all contaminants at a given location,  where each
chemical-specific estimate of risk or hazard represents exposures from multiple pathways.
Implicit in the summation of risk and hazard is the assumption that the effects of exposure to
more than one chemical are additive. This simplifying assumption does not consider similarities
or differences in target organ toxicity, mechanism(s) of action, or the possibility of synergistic or
antagonistic effects of different chemicals in the mixture.

2.6.7. Summary of Human Health Baseline Risks and Hazards Associated
with Contaminants

    Estimated baseline risks and hazards for the GSA OU were evaluated for adults on site
exposures and residential exposures, as well as additive potential risk.  These are  described
below, followed by a brief discussion of uncertainty.

2.6.7.1. Adult Onsite Exposures

    The AOS exposure Scenario addresses potential health risk attributable to contaminants in
soil, where an AOS is presumed to work in the immediate vicinity of the contamination over the
entire period of employment at the site (25 years).
                                                    v
    We evaluated potential AOS exposure to contamination by calculating the associated risk and
hazard for two scenarios.  The first of these scenarios pertains to potential AOS  exposure to
contaminated subsurface soil through inhalation of VOCs volatilizing from  subsurface soil to air.
The second scenario pertains  to potential AOS exposure  to contaminated surface  soil from
inhalation of resuspended particulates, dermal absorption of contaminants following direct
contact with contaminated soil, and incidental ingestion.
    Risk and hazard associated with AOS exposure to contaminated subsurface soil through
inhalation of VOCs volatilizing from subsurface soil (0.5 to 12.0 ft) to ambient air was evaluated
in the vicinity of three exposure locations in the GSA OU:   1) the Building 875 dry well area,
2) the central GSA, and 3) the eastern GSA. Individual potential excess lifetime  cancer risks
were 2 x 10~7 for the Building 875 area, 7 x 10~7 for the central GSA,  and 2 x  10~7 for the
eastern GSA.  The  estimated noncancer His were  6.2 x 10~3 for the Building  875 area,
1.2 x 10-3 for the central GSA, and  1.3 x 10-3 for the eastern GSA.
    The potential excess lifetime cancer risk and noncancer His for the  AOS exposure to
contaminants volatilizing from subsurface soil to  ambient  air are within  the acceptable range
(cancer risk < 1Q-6 and HI <1) specified by the NCP (U.S. EPA, 1990a).
    Risk and hazard were also evaluated for AOS inhalation exposure to VOCs volatilizing from
contaminated subsurface soil underneath Building 875 and diffusing into the building.  The
exposure scenario for an AOS working inside Building 875 resulted in estimates of individual
potential excess lifetime  cancer risk (1 x 10~5)  and noncancer HI (3 x 10~')-  While  the
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noncancer HI for this scenario is within acceptable limits (HI <1), the potential excess lifetime
cancer risk is within the range (between 10"4 and  lO"6) where risk management measures are
necessary.
   The baseline evaluation of risk and hazard associated with AOS exposure to surface soil
contaminants  yielded estimates of individual excess lifetime cancer risk of 2 x  10~7 for
inhalation of resuspended particulates and 2 x  10~10 for ingestion and dermal absorption of
surface soil contaminants. The corresponding His  are 5.6 x  10~5 for inhalation and 8.5 x 10~3
for ingestion and dermal absorption. The potential excess lifetime cancer risk and noncancer His
for the AOS exposure to surface soil contaminants are within the acceptable range (cancer risk of
<10-6 and HI <1) specified by the NCP (U.S. EPA,  1990a).
   Reference documents for calculations and estimates of potential cancer risk and hazard index
and the results are summarized in Table 6.

2.6.7.2.  Additive Risk and Hazard for Adults Onsite

   Adults working outdoors in the GSA OU could be exposed simultaneously to contaminants
in surface soil (by inhalation of resuspended particulates, and ingestion and dermal absorption of
surface soil contaminants) as well as by inhalation  of the VOCs that volatilize from subsurface
soil.  The vicinity of the central GSA was selected for our calculations of additive risk and HI
associated with AOS exposures because our calculations  indicated higher levels of cancer risk
and HI for this location than for exposures  associated with  the Building 875 dry well area and the
eastern GSA.  Because the Building 875 dry well area, central  GSA,  and eastern GSA are
separated by approximately 200 ft, we did not examine concurrent exposures to  VOCs from the
three sources.
   Table 6 presents the potential additive individual excess lifetime cancer risk and HI estimates
for AOS exposures in the GSA OU.  The values given in Table 6 indicate an estimated total
additive cancer risk of 9 x IQ-7 and a total  additive HI of 9.7 x 10~3.
   The potential additive individual excess cancer risk and additive noncancer His for the AOS
exposure in the GSA OU are within the acceptable range (cancer risk <10~6 and HI <1) specified
by the NCP (U.S. EPA, 1990a).

2.6.7.3.  Residential Exposures

   Risk and  hazard were evaluated for potential  RES use of contaminated ground water at:
1) hypothetical wells located at the site boundary  near the Building 875 dry wells and the eastern
GSA debris burial trenches,  and 2) at existing water-supply wells CDF-1 and SR-1.
   We calculated the risk and hazard associated with potential RES use of contaminated ground
water from a hypothetical water-supply well  located  at the site boundary  nearest to the
Building 875 dry wells. The  individual excess lifetime cancer risk attributable to the potential
use of ground water at this location is 7 x 10~2, and the corresponding HI is 560. These values
estimate that if ground water at  the site boundary  in the central GSA were to be used for
residential purposes on a regular basis for  30 years, there would be an unacceptable incremental
excess cancer risk and unacceptable noncancer health effects.
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   We also evaluated risk and hazard associated with potential residential use of contaminated
ground water at the site boundary nearest to the eastern GSA debris burial trenches.  The
individual excess lifetime cancer risk attributable to the potential use of ground water at this
location is 5 x 10~5, and the corresponding HI is 5 x lO"1.  In addition, we calculated the risk
and hazard associated with potential use of contaminated ground water at two offsite locations,
wells CDF-1 and SR-1.  The individual excess lifetime cancer risks attributable to the potential
use of ground water at these locations are 1 x  10~5 and 2 x  10~5, respectively.  The
corresponding His are 1.4 x 1(H and 1.6 x 10~1. While the noncancer HI for these scenarios are
within acceptable limits (HI <1), the potential excess lifetime cancer risk is within the range
(between 10"4 and lO"6) where risk management measures are necessary (U.S. EPA, 1990a).
   Reference documents for calculations and estimates of potential cancer risk and hazard index
and the results are summarized in Table 6.

2.6.7.4.  Uncertainty in the Baseline Public Health Assessment

   Uncertainties are  associated with  all estimates  of  potential carcinogenic risk  and
noncarcinogenic hazard. For example, the exposure parameters recommended by the U.S. EPA
(1990b; 1991) are typically obtained from the 90th or 95th percentile of a distribution; they are
not necessarily representative of an average individual or of average exposure conditions.
Consequently, use of multiple upper-bound parameters may contribute to overly conservative
estimates of potential exposure, risk, and hazard.
   In addition, the total cancer risk and/or total HI was calculated by summing risk of HQs for
all contaminants at a given  location, where each chemical-specific estimate  of risk or hazard
represents exposures from multiple pathways. Implicit in the summation of risk and hazard, is
the assumption that the effects of exposure to more than one chemical  are additive.  This
simplifying  assumption does not consider similarities or differences in target organ toxicity,
mechanism(s) of action, or the possibility of synergistic or antagonistic  effects  of different
chemicals in the mixture.
   Other uncertainties associated  with the estimates of risk and hazard are OU-specific and are
related to  assumptions  made  in  the  modeling  conducted  to  provide exposure-point
concentrations, which were subsequently used to calculate risk and hazard. Modeling was
conducted to provide estimates of exposure-point concentrations that were used to calculate risk
and hazard associated with exposure to contaminated ground water migrating from the central
and eastern GSA source areas to potential  receptor wells CDF-1, SR-1 and at hypothetical wells
at the site boundary as discussed in Section 2.6.3.
   The following assumptions were made in the ground water modeling, which may result in
uncertainties associated with the risk and hazard estimates:
    1.  The health conservative assumption was made that the 95% UCL for TCE at the central
       and eastern GSA source areas will  reach the site boundary.
   2.  Human exposure was assumed to result from potentially contaminated  ground water if a
       hypothetical well were to be installed .at the site boundary in the near future and was used
       for residential purposes on a regular basis.  However, water in this area is not currently
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       used for domestic purposes, and Removal Action remediation activities are currently
       underway to remove ground water contaminants.
       In addition, the private land directly adjacent to the GSA source areas is open rangeland,
       and we are not aware of any plans to build homes or install wells there in the near future.
   3. The source terms for plume migration in both the central and eastern GSA were assumed
       to remain constant despite ongoing and planned remediation activities in the GSA. Any
       change in the source term would result in a direct proportional change in the exposure-
       point concentration used to calculate risk and hazard.
   4.  Both the source concentration and volumetric flow rate, which define the source term,
       were estimated at the high end of their expected range.
   5. A dilution factor was applied to well  CDF-1 to estimate exposure-point concentrations
       based on contaminant concentrations detected in different water-bearing  zones from
       which well CDF-1 pumps water.  Changes in the dilution factor would cause a direct
       proportional change in the estimated TCE exposure-point concentration used to  calculate
       risk and hazard.
   6. Other assumptions were made to define model parameters such as porosity, ground water
       velocity, dispersivity ratio, and TCE decay half-life used in modeling.  The sensitivity of
       the  predicted maximum  exposure-point concentration to these  input parameters  is
       discussed in Appendix P-20 of the Site 300 SWRI.
   The cumulative excess cancer risk calculated for Building 875 indoor air was based on VOC
concentrations from soil samples collected from the vicinity of the Building  875 dry  well pad
prior to startup of the SVE system. It is likely, due to ongoing soil remediation activities through
SVE, that current VOC soil concentrations are lower than  what was used to calculate excess
cancer risk in the baseline risk assessment. In addition, Building 875 is located approximately
35 ft from  the dry well pad source area.  Therefore, the soil concentration and resulting soil
vapor concentrations under Building 875 are likely to be lower than those used to calculate the
inhalation risk inside Building 875.

2.6.8. Summary of the Baseline Ecological Assessment

   The baseline ecological assessment, conducted to evaluate the potential for adverse impact to
plants and animals from long-term exposure to contaminants in the GSA OU, determined that
VOCs do not pose ecological risk in this area. This  determination was based on estimates of
potential hazard from exposure to contaminants that  were calculated  for mammal and aquatic
species that could potentially inhabit this area, as well as biological surveys conducted to
determine which species actually inhabit or migrate through the GSA.
   A detailed discussion of the baseline ecological assessment can be found in  Section 1.6.4.1 of
the GSA FS (Rueth and Berry, 1995).

2.7.  Description of Remedial Action  Alternatives

   The FS for the GSA OU presented three  remedial action alternatives to address 1)  potential
risk posed by ingestion of VOCs in ground water, and 2) potential VOC inhalation risks inside
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Building 875. The three remedial action alternatives are summarized in Table 7. It should be
noted that the estimated costs for all alternatives presented in this ROD are lower than the cost
estimates presented in the GSA FS and Proposed Plan. This is due to subsequent modifications
to the  1) contingency point-of-use treatment component based on negotiations with the well
owner, and 2) ground water monitoring component based on changes made to the eastern and
central GSA treatment facility monitoring program permit requirements.

2.7.1. Alternative 1—No Action

   A no-action alternative is required by CERCLA as  a  basis from  which to develop and
evaluate remedial alternatives and is the postulated basis of the baseline risk assessment. Under
a no-action response, all current remedial activities in the GSA OU would cease.  However, the
following activities would be performed:
   •   Monitoring of VOCs in ground water, reporting, maintenance, database management, and
       quality assurance/quality control (QA/QC).
   •   Administrative controls including restricting access to or activities in certain areas  of
       contamination, as necessary.
   Modeling indicates that ground water VOC  concentrations  would be reduced to drinking
water  standards through natural  attenuation  and degradation  after 75  years  under the
Alternative 1 scenario.  Ground water monitoring would be conducted for the 75-year period
plus five years of post-"remediation" monitoring.
   The estimated 80-year present-worth cost of Alternative 1 is $3.47 million.  Present-worth
cost analysis is a method of evaluating total costs (i.e., the cost of each remedial alternative) for
projects that vary in duration by discounting all costs to a common base year (1995) to adjust for
the time value of money.  The  present-worth cost represents the  amount of money, which  if
invested in the initial year (1995) of the remedial action and dispersed over the life of the project,
would be sufficient to cover all associated costs.

2.7.2.  Alternative 2—Exposure Control

   The objective of Alternative 2 is to protect human health by preventing human exposure  to
TCE and other VOCs through ingestion  of ground water from existing water-supply wells by
reducing VOC concentrations in water from these wells to drinking water standards (MCLs)
through POU treatment. Drinking water standards and MCLs are  discussed in Section 2.10.1.
Hereafter, drinking water standards will be referred to as MCLs throughout this ROD.
   Alternative 2 includes:
   •   Monitoring and administrative control components of Alternative  1.
   •   Contingency POU treatment for three offsite water-supply  wells: CON-1, CDF-1, and
       SR-1 (Fig. 10).
   As with Alternative 1, reduction of VOC concentrations in ground water through natural
attenuation and degradation  would take approximately 75 years under the Alternative 2 scenario.
Ground water monitoring  would  be conducted for the 75-year period plus  five years  of
post-"remediation" monitoring.
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   The present-worth cost of Alternative 2 is $3.69 million.

2.7.3. Alternative 3—Source Mass Removal and Ground Water Plume
Control

   The objectives of Alternative 3 are to provide increased protection of human health and the
environment by:   1) reducing VOC concentrations in ground  water to MCLs, 2) reducing
residual VOC (DNAPL) mass/volume, 3) reducing VOC concentrations in soil vapor to levels
protective of ground water, and 4) mitigating VOC inhalation risk inside Building 875.  These
objectives will be accomplished through VOC mass removal from contaminant source areas and
plume migration control.
   Alternative 3 includes all the elements of Alternatives 1 and 2 and adds ground water and soil
vapor extraction to remove TCE and other VOCs from ground water, soil and rock. Alternative
3 is divided into two scenarios: Alternatives 3a and 3b.  Both are the same with respect to the
objective and method of subsurface soil/rock remediation, but differ in their ultimate objectives
for ground water remediation. Both Alternative  3a and 3b include:
   •   All elements of Alternatives 1 and 2.
   •   Soil vapor extraction and treatment in the central GSA dry well source area.
   •   Ground water extraction and treatment in the central and eastern GSA.
   Under both Alternatives 3a and 3b, DOE would continue to operate the existing soil vapor
extraction system at the central GSA dry well area to reduce VOC concentrations in soil vapor to
levels protective of ground water and to mitigate VOC inhalation risk inside Building 875.
Modeling indicates that soil vapor extraction would reduce soil vapor VOC concentrations to the
remediation goals within  10 years. The ground water remediation components  of Alternatives
3a and 3b are discussed further below.

2.7.3.1 Alternative 3a—Source Mass Removal, Restoration of the Regional
Aquifer and Ground Water Plume Control

   Under Alternative 3a, DOE would expand the existing ground water extraction and treatment
system in the central GSA dry well area to prevent migration of VOCs above MCLs into the
regional aquifer. In addition, ground water in the eastern GSA debris burial trenches area and
the debris burial trench area west of the sewage  treatment pond would be extracted and treated to
reduce VOC concentrations to MCLs in the alluvial and regional aquifers.
   Modeling indicates that TCE concentrations in the shallow aquifer in the central GSA dry
well area need to be reduced to  100 u^g/L to prevent migration of VOCs above MCLs into the
regional  aquifer.  After the  100 u,g/L  remediation goal is achieved, ground water extraction
would be discontinued and natural attenuation would reduce VOC concentrations in the shallow
water bearing zone (Qt-Tnsc \ hydrogeologic unit) to MCLs.
   The existing ground water extraction and treatment system in the eastern GSA debris burial
trenches area would continue to operate to reduce VOC concentrations in ground water to MCLs
in the shallow and regional aquifers.
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   Modeling  indicates that  ground water extraction would reduce  ground water VOC
concentrations in Building 875 and debris burial trenches areas to MCLs within 30 years and
10 years, respectively.  Modeling also indicates that an additional 35 years may be required to
reduce VOC concentrations to MCLs in the shallow aquifer in the central GSA through natural
attenuation and dispersion.  The configuration and operation of both the central and eastern GSA
treatment systems would be optimized during remediation to maximize system efficiency.
Ground water monitoring would be conducted throughout this 65-year period to achieve MCLs.
in both the shallow and regional aquifer plus five years of post-remediation monitoring.
   The estimated 70-year present-worth cost of Alternative 3a is $17.17 million.

2.7.3.2 Alternative 3b—Source Mass Removal, Restoration of the Shallow
and Regional Aquifer and Ground Water Plume Control

   Alternative 3b consists of all components of Alternative 3a but continues active ground water
extraction and treatment in the central GSA dry well area until MCLs are reached in all affected
ground water.  Modeling indicates that ground water extraction in the central GSA dry well area
would reduce VOC concentrations to current MCLs in 55 years.  Ground water monitoring will
be conducted  throughout the 55 years of remediation, plus five years of post-remediation
monitoring.
   The estimated 60-year present-worth cost of Alternative 3b is $18.90 million.  This estimated
cost for Alternative 3b is slightly lower than the estimated cost presented in the GSA  FS
($19.75 million) for reasons already discussed in the introduction to Section 2.7.

2.8.  Summary of Comparative Analysis of Alternatives

   The characteristics of the three alternatives were evaluated against the nine EPA evaluation
criteria:
   •   Overall protection of human health and environment.
   •   Compliance with ARARs.
   •   Short-term effectiveness.
   •   Long-term effectiveness and permanence.
   •   Reduction of contaminant toxicity, mobility, or volume.
   •   Implementability.
   •   Cost effectiveness.
   •   State acceptance.
   •   Community acceptance.
   As specified by EPA, the two most important criteria are adequate protection of public health
and the environment and compliance with all Federal and State ARARs.  In the following
sections and Table 8, Alternatives 1  through 3  are  compared against these nine criteria.
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Additional details of the evaluation of these remedial alternatives  with  respect to the EPA
evaluation criteria can be found in Chapter 5 of the GSA FS (Rueth and Berry, 1995).

2.8.1. Overall Protection of Human Health and the Environment

   •   Alternative 1 does not actively  remediate contaminated soil or ground water and thus
       would not protect human health or the environment because the potential beneficial uses
       of ground water would not be readily  restored and the potential risk associated with the
       inhalation of VOCs above health-based concentrations in Building 875 are not mitigated.
   •   Alternative 2 protects human health by preventing ingestion of ground water containing
       VOCs above MCLs.  However, because VOCs are not actively remediated, potential
       beneficial uses of ground water would  not be readily restored. As with Alternative 1,  this
       alternative does not prevent  potential inhalation of VOCs above  health-based
       concentrations  in Building 875.

   •   Alternative 3a uses  exposure control  methods and administrative  controls to provide
       initial protection to human health. This alternative would also protect human health by
       restoring and protecting the beneficial  uses of ground water in the Tnbsi regional aquifer
       through active remediation. Alternative 3a protects human health by preventing potential
       inhalation of VOCs  above health-based concentrations in Building 875 by reducing  soil
       vapor VOC concentrations through soil vapor extraction.  Alternative 3a would employ
       ecological  surveys  and appropriate  response actions,  if necessary, to protect  the
       environment.

   •   Alternative 3b uses exposure control methods and administrative  controls to provide
       initial protection to human  health.  This alternative also protects  human health by
       restoring and protecting the  beneficial uses of ground water in both the shallow  and
       Tnbsj regional aquifer through active remediation. Alternative 3b protects human health
       by preventing potential inhalation of VOCs above health-based concentrations in
       Building 875 by  reducing soil vapor VOC concentrations through soil vapor extraction.
       Alternative 3b employs ecological surveys and appropriate response actions, if necessary,
       to protect the environment.

2.8.2. Compliance with ARARs

   A complete discussion of potential  ARARs related  to  the  three  proposed remedial
alternatives is presented in the GSA FS, and summarized in Section 2.10 of this report.
   •   Alternative  1  meets all ARARs  if natural  attenuation  and dispersion  reduce  VOC
       concentrations in ground water to MCLs. If natural  attenuation and dispersion do  not
       occur, VOC concentration would remain well above  MCLs, which would not meet the
       requirements of the  following ARARs:  Safe Drinking Water Act, the Region V Basin
       Plan, or State Resolutions 68-16 and 92-49.
   •   Like Alternative 1, Alternative 2 would rely  solely on natural attenuation to meet
       remediation goals, and therefore  may not comply with the requirements of the Safe
       Drinking Water Act, the Region V Basin Plan, and State Resolutions  68-16 and 92-49.
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UCRL-AR-124061            Final ROD for the GSA Operable Unit, Site 300              January? 7997


   •   The goal of Alternative 3a is to use active soil vapor and ground water remediation to
       meet the requirements  of the Safe Drinking Water Act, the Region V Basin Plan, and
       State Resolutions 68-16 and 92-49 in the Tnbsi regional aquifer.  This alternative relies,
       in part, on natural attenuation and dispersion, and therefore may not meet these ARARs
       in the alluvial aquifer in the central GSA.

   •   Alternative 3b would use active soil vapor and ground water remediation to meet all
       ARARs in both the alluvial and Tnbsj regional aquifer.

2.8.3. Short-Term Effectiveness

   •   Alternative 1 would not remove VOCs from the subsurface.  Therefore, this alternative
       would not be effective in short-term remediation of the site.
   •   Alternative 2, while preventing human exposure through ingestion of VOCs in ground
       water from existing water-supply wells, does  not address risk to human health from
       potential exposure to VOC vapors inside Building 875. Because this alternative does not
       actively reduce VOC mass, it would not provide short-term remediation of the site.
   •   Alternative 3a would immediately protect the public from potential exposure pathways.
       This alternative uses ground water and soil vapor extraction  to  immediately begin
       removing VOCs and reducing VOC  concentrations in ground  water and soil vapor, and
       would be effective in the short term.
   •   Like Alternative 3a, Alternative 3b immediately protects the  public  from potential
       exposure pathways.  This alternative uses ground water and soil vapor extraction to
       immediately begin removing VOCs  and reducing VOC concentrations  in ground water
       and soil vapor.
   •   All  alternatives would be effective in the short term by protecting site workers and the
       community during the remedial action by preventing potential exposure through the use
       of administrative controls. No adverse environmental impacts are anticipated.

2.8.4. Long-Term Effectiveness and Permanence

   •   Alternative 1 would not use active measures to reduce VOCs in ground water. It does not
       address potential risk  from  ingestion  of VOCs in ground water from existing water
       supply wells or potential inhalation risk inside Building 875. Therefore, this alternative
       would not be effective in long-term remediation of the site.
   •   Alternative 2 would provide protection from exposure risk at existing water-supply wells
       by providing immediate and long-term response if VOCs greater than MCLs reach these
       wells.  However, since  this alternative does not reduce VOC mass or address potential
       inhalation risk inside Building 875, it would not be an effective long-term remedy.
   •   Alternative 3a would use ground water and soil vapor extraction to permanently reduce
       VOC concentrations to MCLs in the Tnbsj regional aquifer.  However, this alternative
       relies on natural attenuation to reduce VOC concentrations to MCLs in  the alluvial
       aquifer in the central GSA.  Because the reliability of natural attenuation to reach MCLs
       is uncertain, this alternative may not  provide an effective long-term remedy.  Alternative


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UCRL-AR-124061            Final ROD for the GSA Operable Unit, Site 300              January 1997


       3a would permanently reduce VOC soil vapor concentrations to levels protective of
       ground water and mitigate inhalation risk inside Building 875.
    •   Alternative 3b would provide an effective long-term remedy by permanently reducing
       VOCs  to  MCLs  in both the alluvial and Tnbsi regional  aquifer  through active
       remediation. Alternative 3b will permanently reduce VOC soil vapor concentrations to
       levels protective of ground water and mitigate inhalation risk inside Building 875.

2.8.5. Reduction of Contaminant Toxicity, Mobility, or Volume

    •   Alternatives 1 and  2 do  not actively remove VOCs from  the subsurface.  These
       alternatives are dependent on natural attenuation processes that may not be effective in
       reducing toxicity, mobility, or volume of the VOCs.
    •   Soil vapor and ground water extraction in Alternative 3a would significantly reduce the
       toxicity, mobility, and volume of  contaminants  in  the subsurface  through active
       remediation measures.
    •   Alternative  3b will significantly reduce  the toxicity, mobility,  and volume  of
       contaminants in the subsurface through active ground water and soil vapor remediation.

2.8.6. Implementability

    •   Alternative 1 could be  easily implemented by utilizing the  existing ground water
       monitoring program.
    •   Alternative 2 could be implemented using the existing ground water monitoring program
       and readily available services and materials for POU treatment system construction and
       operation.
    •   Alternative 3a could be easily implemented utilizing soil vapor and ground water
       extraction and treatment systems which are currently in place, permitted, and operating in
       the GSA.   Modifications to these systems proposed in Alternative 3a are readily
       implementable.
    •   Alternative  3b could  be easily  implemented  utilizing soil vapor and ground water
       extraction and treatment systems which are currently in place, permitted, and operating in
       the GSA.   Modifications to these systems proposed in Alternative 3b are readily
       implementable.

2.8.7. Cost Effectiveness

    The cost estimates prepared for the remedial alternatives, as well as the assumptions made in
preparing these estimates,  are described  in detail in Appendix F of the GSA FS.   The cost
estimates may change as the result of modifications during the remedial design and construction
process.   Any revisions to the cost estimates will  be presented in the Remedial Design
Document.
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   •   The estimated present-worth cost of Alternative 1 is $3.47 million for up to 80 years of
       ground water monitoring.  This alternative has the lowest cost because it does not include
       active remedial actions.
   •   The estimated present-worth cost of Alternative 2 is $3.69 million.  This includes up to
       80 years of ground water  monitoring and contingency POU treatment at existing water
       supply wells, if necessary.  Alternative 2 has a higher cost because it includes capital
       construction projects  (construction and installation of POU  treatment systems) and
       ground water  monitoring,  but  no active  remediation by long-term  extraction and
       treatment.
   •   The estimated present-worth cost of Alternative 3a is $17.17 million.  This includes up to
       10 years of SVE, ground water extraction for up to 10 years in the eastern GSA and 30
       years in the central GSA, and up to 70 years of ground water monitoring.  The higher cost
       of Alternative 3a is due to capital- construction projects, extraction and treatment system
       modifications, installation  of additional extraction wells and piezometers, as well as long-
       term extraction and treatment system  operation and maintenance and ground water
       monitoring.  The costs incurred to implement  Alternative 3a are  associated with the
       active remediation of soil and ground water in the GSA.  Remediation  would continue
       until VOC concentrations in ground water are reduced to MCLs in: 1) the Tnbsj regional
       aquifer in the central GSA, and 2) the alluvial aquifer and the Tnbsi regional aquifer in
       the eastern GSA.  Also, VOC concentrations in soil vapor will be reduced to levels
       protective of ground water and to mitigate inhalation risk inside Building 875.
   •   The estimated present-worth cost of Alternative 3b is $18.90 million.  This includes up to
       10 years of SVE, ground water extraction for up to 10 years in the eastern GSA and 55
       years in the central GSA, and up to 60 years of ground water monitoring.  This alternative
       has the highest present-worth cost because it includes all the costs of Alternative 3a but
       operates the central GSA ground water extraction system for an additional 25 years. As
       with Alternative 3a, the costs incurred to implement Alternative  3b are associated with
       the active remediation of soil and ground  water in the  GSA.  However,  the cost of
       Alternative 3b is higher due to the continued remediation of ground water to reduce VOC
       concentrations to MCLs  in  both the  alluvial and Tnbs, regional  aquifers.  The cost
       difference between Alternative 3a and 3b represents the additional cost of remediating
       ground water in the Qt-Tnsci aquifer in the central GSA to reduce VOC concentrations to
       MCLs.

2.8.8. State Acceptance

   The State regulatory agencies, DTSC, and CVRWQCB have  provided ARARs for the site,
reviewed and evaluated the remedial technologies and alternatives, participated in the selection
of the final remedy, and provided oversight and enforcement of State environmental  regulations.
The DTSC and the CVRWQCB concur with the U.S. EPA and DOE that Alternative  3b provides
the best balance of trade-offs with respect to the  evaluation criteria.
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2.8.9. Community Acceptance

   The regulatory agencies have monitored and reviewed public acceptance of the final selected
remedy.  Public comments concerning each alternative and the selected remedy have been
considered and used, as appropriate, in the preparation of this ROD. All public comments on the
Proposed Plan, and selected remedy for the GSA are addressed in the Responsiveness Summary
section of this document.

2.9.  Selected Remedy

   DOE, U.S. EPA, CVRWQCB, and DISC agree that Alternative 3b is the most appropriate
remedial alternative, considering the CERCLA evaluation criteria. Under Alternative 3b, DOE
will continue subsurface remediation using ground water extraction coupled with SVE to reduce
potential risk and contaminant mass. Throughout the remediation process, other more innovative
remediation technologies will be considered to enhance VOC mass removal and treatment of
extracted soil vapor and/or ground water. In situ innovative technologies for VOC remediation
will also be considered.
   This discussion of the selected remedy includes cleanup goals for the media of concern,
details of the  remedy  components,  extraction  and treatment system design and operation,
performance evaluations, consideration of innovative technologies, reporting, and a summary of
preliminary cost estimates.

2.9.1. Cleanup Goals

   The objectives of the selected remedial alternative are to:  1) reduce VOC concentrations in
ground water  to levels protective of human health and the environment, 2) reduce VOC
concentrations in soil vapor to meet ground water cleanup goals, and 3) mitigate VOC inhalation
risk inside Building 875.
   Objectives 1 and 2 will be accomplished by ground water extraction and treatment to reduce
VOC  concentrations to MCLs, supplemented with soil vapor extraction and treatment to reduce
soil vapor concentrations to meet ground water cleanup goals.  Objective 3 will be accomplished
with the existing SVE system used to accomplish objectives 1 and 2.  Soil vapor concentrations
protective of ground  water  are  significantly lower than concentrations  required to reduce
inhalation risk inside Building 875.

2.9.1.1.  Ground Water Cleanup Goals

   The cleanup goal for ground water is to reduce VOC concentrations to MCLs in all impacted
ground water in the GSA. The current MCLs for the VOC contaminants of concern in ground
water in the GSA are presented  in Table 9.  Ground water monitoring will be conducted as
discussed in Sections 2.9.2.1 and 2.9.3.1 to determine when MCLs for the contaminants of
concern have been achieved in ground water.
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2.9.1.2. Soil Vapor Cleanup Goals

Protection of Ground Water

    One objective of SVE at  the Building 875 dry well pad is to reduce VOC mass and
concentrations to meet ground water cleanup goals. The VOCs in the vadose zone will be
remediated to the extent technically and economically feasible to minimize further degradation
of the ground water by the contaminants in the vadose zone. It is generally preferable from a
technical and cost perspective to cleanup contamination in the vadose zone before it reaches the
ground water. The vadose zone cleanup will be achieved when it is demonstrated that:
    1)  The remaining vadose zone VOC contaminants no longer cause concentrations in the
       leachate to exceed the aquifer cleanup levels, based on an interpretation of soil vapor data
       using an appropriate vadose zone model. Leachate is the mobile portion of water in the
       vadose zone containing soluble constituents that has been leached from the soil in the
       vadose zone.  Aquifer  cleanup levels have been established as MCLs  as  defined in
       applicable Federal and State safe drinking water standards; and
    2)  VOCs have been removed to the extent technically and economically feasible in order to
       meet the aquifer cleanup levels sooner, more cost-effectively, and more reliably.
    The SVE system will be operated until the demonstration is made that  Items 1 and 2 above
have been met, unless the parties consent to the use of an alternate technology for the purpose of
meeting the requirements outlined in Items  1  and 2 above. DOE, U.S. EPA, DTSC, and the
CVRWQCB agree to evaluate the performance of the SVE system, as well as to determine when
vadose  zone cleanup has  been achieved  based on  the  technical  criteria  discussed  in
Section 2.9.3.2.

Risk Reduction within Building 875

    The SWRI baseline risk assessment indicated that the cumulative potential excess cancer risk
from inhalation of indoor air within Building 875 was 10~5. This calculation was based on VOC
concentrations from soil samples collected in the vicinity of the Building 875 dry well pad prior
to the July 1994 startup of the SVE system.  It is likely, due to nearly two years of ongoing SVE
soil remediation, that current VOC soil concentrations are lower than what was used to calculate
this excess cancer risk in the baseline risk assessment. Soil vapor concentrations protective of
ground water are significantly lower than  concentrations that will be required to reduce potential
inhalation risk inside Building 875.  DOE will conduct soil vapor monitoring, as discussed in
Section 2.9.3.2, and use these data to  validate reduction of potential inhalation risk inside
Building 875.

2.9.2. Treatment System Design

    The majority  of the  remediation components are  readily implementable with minor
modifications to the existing soil vapor and ground water extraction and treatment systems at the
GSA OU.
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   The major components of the selected remedy (Alternative 3b) include:
   •   Ground water monitoring  throughout the  predicted 55  years of remediation plus
       five years of post-remediation monitoring.
   •   Administrative controls including access restrictions and  procedures for construction  in
       areas where possible exposure to contaminated media may occur.
   •   Contingency POU treatment for offsite water-supply wells.
   •   Soil vapor extraction and treatment in the central GSA dry well source area.
   •   Extraction and treatment of ground water in the central and eastern GSA.

   The design, operational, and/or implementation details of these  components are discussed  in
detail in the following sections.

2.9.2.1. Monitoring and Administrative Controls

Monitoring

   Currently, the  preliminary ground water monitoring  program for the  selected  remedy
(Alternative 3b) consists of sampling 7 wells quarterly, 89 wells  semiannually, and 12 wells
annually for the first 10 years.  Between years 11 and 55, after  the eastern GSA ground water
extraction system and two of the central GSA extraction wells have been turned off, sampling
frequency will be reduced to semiannually for 39 wells,  and annually for 50  wells. After 55
years, when ground  water  fate and transport modeling predicts that VOC concentrations  in
ground water have  been reduced to MCLs and the central GSA ground water extraction system
can be turned off, ground water sampling will be reduced further to semiannually for 37 wells
and annually for 37 wells for the five  years of post-remediation monitoring.   Samples will be
analyzed for VOCs by EPA Method 601, and some wells in the  central GSA would  also be
analyzed for fuel hydrocarbons by EPA Method 602. If remediation does not show that  cleanup
is proceeding as the modeling predicts, remediation methods will be revisited.
   Consistent with the NCP, the ground water data obtained as part of the monitoring program
will be reviewed at least every five years. If these data indicate that VOC concentrations, ground
water flow direction, and/or velocity  have  changed and significantly affect  the cleanup, the
monitoring program would be re-evaluated.
   Soil vapor concentrations will  be monitored periodically from the  seven  extraction wells
during the predicted 10 years  of SVE to evaluate remediation  progress and provide data for
system optimization.  VOC concentrations in soil vapor  samples  can be  used to determine if
there is preferential VOC  removal from certain SVE wells. This information will be used to vary
the extraction configuration to optimize VOC mass  removal from  soil vapor; i.e., extract from
wells  with  higher VOC soil  vapor  concentrations  while using wells with lower VOC
concentrations as air inlet wells. The  configuration and  operation of the SVE system will be
optimized during remediation to maximize system efficiency.
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    In addition, existing soil vapor monitoring points in the vicinity of Building 875 will be
monitored for TCE and PCE. The TCE and PCE concentrations will be used to periodically
evaluate the effectiveness of SVE in mitigating inhalation risk inside Building 875.  .
    Although the inhalation risk inside Building 875 was calculated by adding the individual
lifetime cancer risk for a total of six VOCs, the sum of the  individual cancer risks for TCE and
PCE (1.11 x 10~5) constitutes the largest portion of the total  additive inhalation cancer risk inside
Building 875 (1.17 x 10~5). For this reason, TCE and PCE will be used as the indicator VOCs
for periodically assessing additive inhalation cancer risk inside Building 875. Once the additive
inhalation risk reaches acceptable levels for TCE and PCE,  soil vapor samples will be collected
and analyzed for all six VOCs originally used to calculate inhalation risk inside Building 875 in
the SWRI. These data will then be used as direct input parameters to the models that were used
to calculate inhalation risk in the SWRI to calculate a total additive inhalation cancer risk inside
Building 875.
    Soil vapor monitoring will be discussed in detail in the remedial design document.
    Specific details of the ground water and soil vapor monitoring network will be presented in
the Remedial Design document.
    Additionally,  surface water from springs 1, 2, and GEOCRK will be sampled and analyzed
for VOCs, drinking water metals, general minerals, high explosives, tritium, and gross alpha and
beta as part of ongoing site-wide program of ecological studies.  The current program of
conducting ecological resource surveys for sensitive species  prior to the initiation of any ground-
disturbing activities will also continue. The need for detailed ecological resource surveys will be
evaluated every five years as part of the contract renewal negotiations between the University of
California and DOE.

Administrative Controls

    The following administrative controls are a component of the selected remedy and are either
currently  in effect or easily  implementable.  Because DOE intends to retain stewardship of
Site 300 for the foreseeable future, existing security patrols, site access restrictions, and fencing
along the  entire perimeter of Site 300 will be maintained. These restrictions will prevent public
access, and thus potential exposure, to the source areas and  areas of highest ground water VOC
concentrations. Additionally, DOE will continue to consider site conditions (especially in the
vicinity of vadose zone contamination) prior to implementing construction of  any facility to
prevent potential worker exposure to subsurface contaminants.

2.9.2.2.  Contingency Point-of-Use Treatment

    POU treatment systems will be installed at offsite water-supply wells CON-1, CDF-1 and
SR-1  (Fig. 10) if VOCs in these wells are at or above MCLs. As part of the monitoring plan,
water-supply wells CON-1 and CDF-1  will be monitored for  VOCs monthly. Guard wells W-
25D-01, W-25D-02, and W-24P-03, located the farthest  downgradient from the  source and
upgradient from water-supply well SR-1, will also be monitored for VOCs.  Well W-24P-03 will
be monitored quarterly, and wells W-25D-01 and  -02 monitored semiannual.  If VOCs are
detected in well W-24P-03, the monitoring frequency of this well will be increased to monthly,
and wells W-25D-01 and -02 monitored quarterly. Should VOCs be detected in well W-24P-03,


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provisions will be made to routinely sample well SR-1.  In the event that VOCs at or above
MCLs are detected and confirmed in wells CDF-1, CON-1, or SR-1, implementation of POU
treatment at that well will be discussed with the regulatory agencies and well owner(s).
   Wells CDF-1 and CON-1 are located approximately 100 and 200 ft, respectively, from the
Site 300 GSA boundary.  Due to the close proximity of these wells to the VOC plume, DOE
currently  has a POU  contingency plan in place for these wells  in a  Memorandum  of
Understanding that has been reviewed and approved by the well owner.
   Well SR-1 is located approximately  1.5 miles downgradient from guard well W-24P-03.  No
VOCs have  ever been detected in ground  water collected from W-24P-03, the furthest
downgradient well. In addition, the VOC plume has been receding upgradient back toward Site
300 as result  of remediation efforts and is currently over 2 miles from well SR-1.  However, if
VOCs were detected in guard well W-24P-03, the property owner would be contacted to set up a
contingency plan similar to that established for wells CON-1 and CDF-1.
   The conceptual POU treatment system design consists of a gravity-flow aqueous-phase GAC
treatment system utilizing two GAC canisters connected in series and mounted on a double-
containment skid.  Sampling ports will be provided between the canisters, as well as at the inlet
and exit pipes. Other equivalent treatment technologies may be considered, if appropriate.
   In the event that POU treatment becomes necessary, DOE will develop and submit a plan for
regulatory approval to permanently remedy the affected water supply.

2.9.2.3. Soil Vapor Extraction and Treatment

   SVE will be  used as the primary remedial  technology to:   1)  reduce vadose zone
contamination, including potential DNAPLs in unsaturated bedrock, to concentrations protective
of ground water, and 2) reduce potential inhalation risk inside Building 875.  Most vadose zone
contamination is found in the immediate vicinity  of the Building 875 dry well pad, so SVE
efforts will be focused in that area.
   Residual DNAPLs may be in the vadose zone and dewatered bedrock in the vicinity of the
Building 875  dry well pad. The dewatered zone consists of bedrock that was formerly saturated
prior  to the  initiation of ground water extraction  activities in the  central  GSA,  but is now
unsaturated or dry due to pumping. SVE and treatment would also address residual DNAPLs.
SVE has been identified as a  technology that can effectively remediate volatile DNAPLs in the
unsaturated zone and prevent uncontrolled migration of VOCs in soil gas (U.S. EPA,  1992d;
1993b).  In addition, when SVE is coupled with lowering of the water  table through ground
water extraction, residual DNAPLs can  be removed from the area below the original water table
elevation (U.S. EPA, 1992d).
   In July 1994, soil vapor extraction and treatment activities were initiated in the central GSA
Building 875  dry well pad area. The current SVE system uses seven extraction wells and treats
the vapor with two 140-lb vapor-phase  GAC canisters connected in series prior to discharge to
the atmosphere. The locations of the SVE wells are shown in Figure 11. VOC concentrations in
the SVE-combined influent stream have decreased from a high of 450 ppmv/v in July 1994 to
current concentrations  of 5  ppmv/v or below in the second quarter  1996.  Similarly, VOC
concentrations in soil vapor samples from the individual SVE wells have decreased  from a
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UCRL-AR-124061           Final ROD for the GSA Operable Unit, Site 300              January 1997


maximum concentration of 600 ppmv/v in well W-7I  at system startup to a maximum of 33
ppmv/v in well W-875-07 in the second quarter 1996. As of second quarter 1996, 27,238 grams
of VOCs have been removed in the central GSA through SVE.
   Soil vapor is currently extracted at rate of approximately 20 standard cubic ft per minute.
Based on field observations, we estimate that the current system adequately captures the soil
vapor plume in the Building 875 dry well pad source area and that no additional SVE wells are
necessary. The necessity of performing SVE at other locations in the GSA OU will be evaluated
as remediation progresses.   Other equivalent soil vapor treatment technologies may be
considered, if appropriate.
   The seven SVE wells are also used for ground  water extraction and are successfully
maintaining a dewatered zone in the immediate vicinity of the Building 875 dry well pad.
Dewatering has exposed more soil/rock to the applied vacuum of SVE,  thereby significantly
enhancing VOC mass removal. This dewatered zone will continue to be maintained while SVE
is operating.
   The central GSA treatment is a  dual soil vapor and ground water extraction and treatment
system, and both systems will initially be operated simultaneously. Upon reaching conditions
presented in Section 2.9.3.2, the soil vapor system will be shut down and only the  ground water
extraction and treatment system will operate.  Should  site conditions change or  ground water
monitoring indicate that soil vapor concentrations have rebounded and will cause ground water
to exceed ground water cleanup goals, the soil vapor system will be restarted  and operated as
appropriate until such conditions cease. DOE agrees to operate the dual soil vapor and ground
water extraction and treatment system to reduce ground water VOC concentrations to meet
ground water cleanup goals in the most efficient manner.
   During preparation of the remedial design report and throughout the life of the project, DOE
may conduct more extensive testing to determine the effective vacuum influence and to optimize
performance.  Optimization may include expanding the SVE system with additional existing
wells to increase the area of influence, and/or implementing cyclic operation (e.g., alternating
periods when the system is on and off) to maximize the rate of VOC mass removal.

2.9.2.4.  Ground Water Extraction and Treatment

Eastern GSA

   As shown in Figure 8, ground water concentrations  exceed MCLs in the eastern GSA in the
vicinity of the former debris burial trench area, east of the sewage treatment pond.  Ground water
extraction and treatment in this area is designed to reduce ground water VOC concentrations to
MCLs.
   The eastern GSA ground water  extraction system has been operating since July 1991, and
currently consists of three extraction wells pumping a total of up to 46 gal per minute (gpm). As
of second quarter 1996, over 76 million gal of ground water have been extracted  and treated in
the eastern GSA  ground water treatment system with 4,417 grams of VOCs removed from
ground water.
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   Data collected through fourth quarter 1995 indicate that TCE concentrations have been
generally decreasing in all eastern GSA alluvial wells since 1992. There was an average TCE
concentration decrease of 75% in eastern GSA alluvia] wells between the historical maximum
concentration  and the concentration in third quarter 1994.  The  maximum observed TCE
concentration  in eastern GSA alluvial  wells in fourth quarter 1995 was 18 \ig/L in well
W-26R-01, a significant decrease from the historical maximum concentration of 74 jag/L TCE in
well W-26R-03 in January 1992.
   The 1 p.g/L isoconcentration contour for the ground water VOC plume in the eastern GSA
previously extended 4,750 ft downgradient from the debris trench area and  the 5  Jig/L
isoconcentration contour extended 4,625  ft downgradient based on fourth quarter 1991 (SWRI)
data (Fig. 12).  Fourth quarter 1995 data indicate that the 1 \ig/L isoconcentration contour for the
ground water VOC plume now extends only 1,950 ft downgradient from the debris burial trench
area, while the 5 Jig/L isoconcentration contour extends only 600 ft downgradient (Fig. 8).
Remediation efforts in the eastern GSA are thought to be at least partially attributable to this
decrease in plume length.
   VOC concentrations in the regional aquifer in the eastern GSA have also been significantly
decreasing as a result of existing alluvial ground water remediation. TCE concentrations have
decreased in ground water in the Tnbsi regional aquifer from a maximum of 71 Hg/L in third
quarter  1992, to a maximum of 19.2 jig/L in fourth quarter 1995 as shown in Figures 13 and 9,
respectively.   In this area,  the alluvium and underlying regional aquifer are hydraulically
connected, and contamination in the regional aquifer is a result of downward vertical migration
of contaminants from the alluvial aquifer.  An extraction well in the regional aquifer in the debris
burial trench area was not considered due to concerns that pumping the regional aquifer would
accelerate/facilitate downward vertical contaminant migration from the overlying source in the
alluvium into  the Tnbsi.  If remediation of the alluvial aquifer does not  appear  effective in
removing VOCs from ground water in the regional aquifer in the future, direct remediation of the
regional aquifer in the eastern GSA will be considered.
   Based on  modeling and field  data  associated with the existing extraction  system,  the
extraction well configuration shown in Figure  11 sufficiently captures the plume in the eastern
GSA to meet remediation goals. The portion of the  plume downgradient of the eastern GSA
extraction wells that is not being  actively captured  has been retreating since ground water
extraction was initiated. We anticipate this trend will continue.  Therefore, no additional  wells
are necessary at this time. The effectiveness of this system is discussed in Section 1.4.8.2 of the
GSA FS.
   Ground water modeling predicts  that the eastern GSA ground water extraction and treatment
system will remediate ground water to MCLs in five  years. However, we have conservatively
assumed that this system will need to operate for ten years.
   In the GSA FS,  a low-profile shallow-tray  air stripper was the chosen treatment system for
ground water in the eastern GSA. Aqueous-phase GAC was not a selected technology in the FS
due to concerns regarding possible biofouling  and clogging that might require premature GAC
replacement, and thereby  reduce system efficiency.  The FS also stated that aqueous-phase GAC
treatment was  being further evaluated as a component of the final system design. Since issuing
the GSA FS in October 1995, aqueous-phase GAC was evaluated for ground water  treatment in
the eastern GSA. This evaluation consisted of:
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VCRL-AR-124061          » Final ROD for the GSA Operable Unit, Site 300              January 1997


    1.  Reviewing ground water chemistry data from eastern GSA extraction wells to evaluate
       the potential for carbonate clogging or bacterial biofouling of the GAC system.
    2.  Performing a system  test by connecting two aqueous-phase GAC units to the eastern
       GSA treatment system to monitor the effectiveness of GAC in reducing VOCs, and to
       identify potential problems such as biofouling and clogging.
    Two aqueous-phase GAC units were connected in series prior to the air sparging tank. Water
from the eastern GSA extraction wells passed through sediment filters and then went directly
into the  GAC units.  The GAC units were sampled and monitored to ensure VOCs were
effectively removed to the NPDES permit required levels, and to evaluate the potential effects of
biofouling and carbonate clogging on GAC system efficiency. Following treatment in the GAC
units, the water passed through the air sparging tank. The GAC units were evaluated in this
manner for eight months, from December 1995 to August 1996. The  results of this evaluation
indicated that:  1) the aqueous-phase GAG units effectively removed VOCs from ground water to
NPDES permit levels (<0.5 Hg/L), and 2) there is no evidence of system efficiency reduction or
premature replacement of GAC due to biofouling and clogging of the GAC units.
    As discussed in Section 3.3.5.1.1 of the GSA FS, aqueous-phase GAC adsorption is a well
established and effective technology for treating chlorinated solvents in ground water. Activated
carbon removes contaminants from water by adsorbing them onto its surface. A GAC adsorption
system consists of a packed column with an internal plumbing system  to distribute the water
evenly through the carbon bed. Organic compounds adsorb onto the surface of the GAC as the
water flows through the fixed bed.
    Aqueous-phase GAC treatment is generally considered to be most effective for low-flow and
low-concentration  applications. Influent TCE concentrations to the eastern  GSA treatment
system have steadily declined from a high of 63 H-g/L in September of 1991 to an average of 8.2
\igfL for the last four quarters (3rd  quarter 1995 to 2nd quarter 1996) and continue to decline.
The GAC technology was demonstrated to be effective in treating the eastern GSA ground water
at these low concentrations.
    Aqueous-phase GAC adsorption is a one-step treatment process as opposed to two-step
treatment necessary with air stripping where VOCs are removed from water and are then driven
into the vapor phase. Following air stripping, the VOC-laden vapors are treated in vapor-phase
GAC units. The aqueous-phase GAC technology,  which is inherently less complex in both
design and  operation than air stripping technology, will incur lower operation and maintenance
costs over the long term.
    The aqueous-phase GAC  technology was evaluated in the eastern GSA and was determined
to be:
    1. Effective in removing VOCs from ground water to NPDES permit levels (<0.5 p.g/L),
    2.  Capable of treating water to  meet all other NPDES permit discharge limits; i.e., pH and
       total dissolved solids, and
    3. More cost effective for long-term operation and maintenance.
    As a result, aqueous-phase GAC has replaced air stripping as the preferred technology for the
treatment of ground water in the eastern GSA.
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UCRL-AR-J2406J            Final ROD for the GSA Operable Unit, Site 300              January 1997


    Extracted ground water will continue to be treated by two to three aqueous-phase GAC units
connected in series (Fig. 14).  Other  equivalent ground water treatment technologies may be
considered in the  future, if appropriate.  The system has a  treatment flow rate capacity of
50 gpm. Ground  water is  treated to reduce VOC concentrations to the National Pollutant
Discharge Elimination System (NPDES) permit requirements of 0.5 fig/L total VOCs.  Treated
water will continue to be discharged by gravity flow to Corral Hollow Creek about 750 ft to the
south.  Discharged treated water will continue to be monitored to ensure compliance  with
NPDES permit requirements issued by the CVRWQCB.
    A portion of the treated  water from the eastern GSA treatment facility may occasionally be
discharged to sewage treatment pond to the west as  makeup water.  During the hot, dry summer
months, approximately 1,000 to 1,500 gal of makeup  water is added to the  sewage treatment
pond to compensate for evaporation,  which is necessary to keep the sewage treatment pond
operating efficiently. It is currently being proposed that treated water from either the eastern or
central GSA treatment facilities be used as this makeup water. In the event that treated water
from the eastern GSA treatment facility is diverted to the sewage treatment pond as makeup
water, this will have little  overall impact on ground water or Corral Hollow Creek as this
treatment facility typically  discharges over 40,000 gal a month.  Due to the low volume of
makeup water required by the sewage  treatment pond, and the limited time frame when makeup
water is required (summer months only), the majority of the treated water from the eastern GSA
treatment facility would continue to be discharged to Corral Hollow Creek, providing recharge to
the  underlying aquifer.

Central GSA

    As shown in Figure 6,  most  VOCs in the GSA OU  subsurface are in  the central GSA,
primarily in the vicinity of the Building 875 dry well pad.  While VOC concentrations in ground
water are above MCLs in the Tnbs i regional aquifer west of the sewage treatment pond (Fig. 7),
the  highest ground water VOC concentrations are in the upgradient overlying alluvial aquifer
(Fig. 6) at the Building 875  dry well pad. Ground water extraction and treatment in this area is
designed to reduce ground water VOC concentrations  to MCLs in both the alluvial and Tnbsi
regional aquifer.
    Since April 1993, a ground water treatment system has been in operation in the central GSA
at the former Building 875 dry well pad area as part of  a CERCLA Removal Action.  Currently,
the  central GSA ground water extraction system pumps a  total of approximately 0.3 gpm from
seven extraction wells located in the vicinity of the Building 875  dry well pad (Fig. 11).  This
very low flow rate is a result of the successful dewatering of the area. As  of second quarter
1996, over 568,000 gal of  ground  water have been extracted and treated in the central GSA
ground water treatment  system and 3,932 grams of VOCs removed from ground water.  A
comparison of VOC ground water data collected from Qt-Tnscj wells during the third quarter
1994 to the historical maximum observed concentrations  indicates an overall decrease in VOC
concentrations. Specifically, the maximum observed TCE concentration for all Qt-Tnscj wells
in samples collected in the third quarter of 1994 was 10,000 JJ.g/L, representing a decrease from
the  historical maximum observed concentration of 240,000  u\g/L in  a bailed ground water sample
collected from well W-875-07  in  March 1992(Fig. 15).   Third  quarter 1994 analytical data
suggest that ground water samples collected from the  Building 875 dry well pad wells do not
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contain TCE at concentration indicative of the presence of DNAPLs  in the saturated zone.
However, the residual DNAPLs may  be present in soil in the dewatered zone and/or vadose
zone.  The drop in TCE concentrations is thought to be attributable to  ground water and soil
vapor extraction and treatment efforts ongoing in the central  GSA.  We have been  unable to
collect ground water samples from the  dry well pad wells since third quarter 1994 because these
wells have been effectively dried out preventing ground water sample collection.
    Historically, TCE has been detected in ground water samples from  monitor wells located
west of the sewage treatment pond, which are completed in the Tnbsi  regional aquifer (Fig. 16).
Data indicates that VOC contaminants  are in the regional aquifer in the central GSA only where
the regional aquifer directly underlies contaminated portions of the alluvial aquifer, such as the
area immediately west of the sewage treatment pond.  Where present, the Tnscj confining layer
acts as a competent confining layer in the vicinity of Building 875 and the areas to the west,
preventing TCE migration from the shallow Qt-Tnscj aquifer into the  underlying Tnbsj regional
aquifer.
    Data indicate that TCE concentrations have generally been decreasing in all Tnbsi monitor
wells in the central GSA since 1990.  The measured decrease in TCE concentrations may be
attributable to the sealing and abandonment of wells 7 and 19 (Fig. 16) in 1988 and 1989. Prior
to sealing and abandonment, these wells pumped up to 200 gpm and may have reversed the
natural hydraulic gradient, thus causing TCE to migrate into the Tnbsj  from the overlying
alluvium.  When pumping ceased from wells 7  and 19, the pre-pumping hydraulic gradient
appears to have been re-established in the Tnbsi and, as a result, the  TCE  concentration in the
bedrock aquifer have decreased.
    In addition to the seven existing ground water extraction wells, six existing monitor wells
(W-7F, W-7O, W-872-02, W-7P, W-873-06,  and W-873-07) will be converted to ground water
extraction wells. Additionally, one new ground water extraction well, W-7Q, will be installed.
The purposes of these new ground water extraction wells are to maximize contaminant mass
removal in source areas and prevent plume migration in both the alluvial and Tnbsi regional
aquifer. Extraction from these new ground water extraction wells will increase the total central
GSA flow rate from the current 0.3 gpm to approximately 15 gpm.
    Ground water monitor well W-7P will be converted to an extraction well to reduce VOC
concentrations in the Tnbs i regional  aquifer west of the sewage treatment pond.  However,
extraction from this well may not be initiated until alluvial aquifers extraction stabilizes capture
zones and further reduces contamination in the alluvial aquifer.
    In conjunction with source area ground water extraction described above, ground water will
be extracted from three new extraction wells (W-7R, W-7S, and W-7T) to be installed in the
alluvial aquifer about 150 ft west of the sewage treatment pond (Fig. 11).  These three extraction
wells will capture VOCs not captured.by the source area extraction  wells, and prevent VOCs
from migrating into the Tnbsi regional aquifer. Ground water extraction from these three wells
will likely continue until ground water extraction in the source areas is discontinued.
    Modeling predicts that ground water extraction in the central GSA will likely be required for
55 years to reduce VOC concentrations to current MCLs. Extraction from  wells W-873-06 and
W-873-07 will be discontinued after 10 years if VOC concentrations in the alluvial aquifer in
these source areas has reached MCLs, as modeling predicts.
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   Ground water extracted in the central GSA will be treated using the existing treatment system
with upgrades including replacement of the existing air sparging tanks with a low-profile tray air
stripper, aqueous-phase granular activated carbon (GAC), or other equivalent technologies to
increase VOC removal efficiency and reduce electrical costs (Fig. 17).
   Ground water treatment will continue to reduce VOC concentrations to meet the Substantive
Requirement of 0.5 u.g/L total VOCs.  Treated water will continue to be discharged to a remote
canyon in the eastern  GSA where the water rapidly infiltrates into  the sandstone bedrock.
Discharged treated water will be monitored to ensure compliance with Substantive Requirements
issued by the CVRWQCB.  A portion of the treated water from the central GSA treatment
facility may occasionally be discharged to the sewage treatment pond to the east as makeup
water during the summer months. In the event that treated water from the central GSA treatment
facility is diverted to the sewage treatment pond as makeup water, the overall impact on ground
water would be minimal as this treatment facility typically discharges 15,000 to 25,000 gal a
month to the canyon in the eastern GSA.  Due to the low volume of makeup water required by
the sewage treatment pond, and the limited time frame when makeup water is required (summer
months only), the majority of the treated water from  the central GSA treatment facility would
continue  to be discharged to  the eastern GSA canyon, providing recharge to the underlying
aquifer.
   Once ground water extraction from Tnbsi well W-7P is initiated, treated ground water will
also  be reinjected into well W-7C, screened downdip of W-7P (Fig. 11).  Reinjection  will
enhance natural contaminant flushing toward extraction well W-7P and expedite remediation of
the Tnbsi regional aquifer.  Hydraulic testing will be performed prior to reinjection to ensure that
reinjection will not adversely affect remediation effectiveness or accelerate plume migration. In
addition to hydraulic testing and prior to reinjection, treated ground water will be analyzed to
verify removal of VOCs to discharge requirements (<0.5 jig/L total VOCs). Analyses will  also
ensure that concentrations of inorganic compounds do  not exceed levels found in water extracted
from the Tnbsj regional aquifer.
   If air stripping is selected as the treatment technology, the vapor stream from the air stripper
will be treated by two vapor-phase GAC canisters connected in series and discharged to the
atmosphere.  The treated vapor stream  will be monitored to ensure  compliance with the
San Joaquin Valley Unified Air Pollution Control District permit requirements. If aqueous-
phase GAC is selected as the remedial technology,  no vapor stream  will exist, therefore air
discharge permits will not be necessary.
   The exact number and location of ground water extraction  wells  will be presented in
subsequent design documents. Similarly, the choice of treatment technologies will be evaluated
on an ongoing basis to implement the most cost-effective technology that  meets all performance
criteria.

2.9.3. Performance Evaluations

   Ground water and soil  vapor monitoring will be conducted throughout the life of the GSA
OU remediation project to evaluate the performance and effectiveness of the treatment systems
in meeting remediation goals.
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UCRL-AR-124061           Final ROD for the GSA Operable Unit, Site 300              January 1997


2.9.3.1.  Ground Water Remediation

   Ground water monitoring, as described in Section 2.9.2.1  will be conducted to evaluate the
effectiveness of ground water remediation in reducing VOC concentrations to MCLs  in the
shallow aquifer and Tnbsi regional aquifer. Details of the ground water monitoring network will
be presented in the Remedial Design document.
   In addition, several new piezometers will be installed for measuring water levels near the
extraction wells to help evaluate ground water capture and remediation effectiveness. Locations
of these piezometers will be determined after ground water extraction begins in order to optimize
piezometer placement, and will be discussed in the Remedial Design report.
   When VOC concentrations in ground water have been reduced to cleanup goals (MCLs), the
ground water extraction and treatment  system(s) will be shut off and  placed on standby.
Modeling indicates that VOC concentrations in ground water in the eastern GSA should be
reduced to MCLs within 10 years following the initiation of remediation and  within 55 years in
the central GSA.  Ground water in the GSA will continue to  be monitored for a period of five
years following  shutdown of the system(s).  Should VOC concentrations in ground  water
"rebound" or increase above cleanup goals, reinitiation of remediation efforts will be discussed
with the  regulatory agencies.  If remediation does  not show that cleanup is proceeding  as
modeling predicts, remediation methods will be revisited.
   As presented in the National Research Council report (NRC, 1994), the ability of restoring
ground water to  MCLs using active pumping is  unlikely at most sites.  If, at some later date,
DOE, U.S. EPA, CVRWQCB, and DTSC determine that it is technically  and economically
infeasible to reduce VOCs in ground water to the cleanup levels established  in this ROD, after all
reasonable efforts have been made, these parties may re-evaluate the need to achieve these goals.
   Throughout the remediation process, innovative remediation technologies will be considered
to enhance VOC mass removal and treatment of ground water,  as discussed in  Section 2.9.4.

2.9.3.2.  Soil Vapor Remediation

   The primary objectives of soil vapor remediation at the central GSA are to: 1) reduce vadose
zone contamination  to concentrations to meet  ground  water cleanup goals, and 2)  reduce
potential  inhalation risk  inside Building 875.   Because the second objective will likely  be
achieved long before achieving the first objective, the performance evaluation  of the central GSA
SVE system will focus on ground water protection,  in accordance with ARARs, State  Water
Resources Control Board Resolution 92-49, and the Region V Basin Plan.
   To monitor the progress  of subsurface soil remediation,  soil vapor concentrations will  be
monitored at dedicated soil vapor sampling points and at SVE wells through the life of the SVE
remediation.  In  addition, DOE/LLNL will evaluate SVE remediation effectiveness by tracking
the cumulative mass of VOCs removed from the Building 875 dry well pad area. The mass of
VOCs removed  from soil vapor will be plotted as a function  of time to  determine when the
cumulative mass removed approaches asymptotic  levels.
   As part of the selected remedy, VOC concentrations in soil vapor will be monitored utilizing
soil vapor sampling points to ensure that the inhalation risk inside Building 875 is adequately
managed. Should existing dedicated soil vapor monitoring points in the vicinity of Building 875
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UCRL-AR-124061            Final ROD for the GSA Operable Unit, Site 300              January 1997
prove insufficient  to demonstrate the effectiveness of soil vapor extraction in mitigating the
potential inhalation  risk in Building  875, additional soil vapor  monitoring points will be
considered.
   The demonstration that the vadose zone cleanup has been achieved to the point where the
remaining vadose  zone VOC contaminants no longer cause concentrations in the  leachate to
exceed the aquifer cleanup levels will be made through contaminant  fate and transport modeling,
trend analysis, mass balance, and/or other means.  This demonstration will  include examination
of the current effects of remaining vadose zone contamination on  the ground water, using an
appropriate vadose zone model, if necessary. In the case that it is demonstrated that the soil
vapor concentration for TCE has  reached 360 parts per billion (ppb) on a volume-to-volume
basis (and similarly derived concentrations for other VOCs) in the vadose zone, the parties agree
that the demonstration has been made that the remaining vadose zone VOC contaminants will no
longer cause concentrations in the leachate to  exceed the aquifer  cleanup level.  If it is
demonstrated that there is no water moving through the vadose zone  and no potential for leachate
to be produced at the current time or in the future, the parties agree that the demonstration that
the remaining vadose zone VOC contaminants  will no longer cause concentrations in the
leachate to exceed aquifer clean-up levels has been made.
   The SVE system will be operated until it is demonstrated that VOC removal from the vadose
zone is no longer technically and economically feasible in order to meet the  aquifer cleanup
levels sooner, more cost effectively, and more reliably.  This feasibility analysis will include
consideration of the follow factors (these factors are not dispositive and other factors may be
considered upon agreement of the parties):
    1)  Whether the predicted concentration of leachate from the vadose (using an  appropriate
       vadose zone model that interprets soil gas data) will exceed the ground water cleanup
       standard;
   2)  Whether the predicted concentration of the leachate from  the vadose zone (using an
       appropriate vadose zone model that interprets soil gas data)  will cause the ground water
       to exceed the aquifer cleanup levels;
   3)  Whether  the  mass  removal rate is  approaching asymptotic levels  after temporary
       shutdown periods and appropriate optimization of the SVE system;
   4)  The additional cost of continuing  to operate  the SVE system at concentrations
       approaching asymptotic mass levels;
   5)  The predicted effectiveness and cost of further enhancements to the SVE system (e.g.,
       additional vapor extraction wells, air injection) beyond  system  optimization of the
       existing system;
   6)  Whether the cost of ground water remediation  will be significantly more if the residual
       vadose zone contamination is not addressed;
   7)  Whether residual mass in the vadose zone will significantly prolong the time to attain the
       ground water cleanup standard;
   8)  Historic data that present the SVE system operating costs per unit VOC mass removed
       from the vadose zone and the concurrent soil vapor VOC concentrations, both as a
       function of  time; and


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   9)  Historic  data that present the ground water extraction and treatment system operating
       costs per unit VOC mass removed from the ground water and the concurrent ground
       water VOC concentrations, both as a function of time.
   Other factors may be considered upon agreement between DOE, U.S. EPA, CVRWQCB, and
DTSC.
   The SVE system  may be cycled on and off in order to optimize SVE operation and/or to
evaluate the factors listed above. DOE, U.S. EPA, CVRWQCB, and DTSC will jointly make the
decision that VOC  cleanup of the vadose zone has been achieved and the SVE system may be
shut off permanently.
   If at  some  later  date, DOE, U.S. EPA, CVRWQCB,  and DTSC determine that it is
technically or economically infeasible to reduce VOCs in the vadose zone to levels which no
longer cause concentrations in the leachate to exceed aquifer cleanup levels, after all reasonable
efforts have been made, the parties will re-evaluate the need to achieve this goal, provided that
VOCs have been removed from the vadose  zone to the extent technically and  economically
feasible and to the satisfaction of the DOE, U.S. EPA, CVRWQCB, and DTSC. This situation
will require a more rigorous feasibility analysis because the incremental benefit of removing
VOCs from the  vadose zone is generally much higher as long as there are VOC contaminants in
the vadose zone that cause concentrations in the leachate to exceed aquifer cleanup levels.
Aquifer cleanup goals must be met even though the goal to reduce VOCs in vadose zone to
levels that no longer cause concentrations in the leachate to exceed aquifer cleanup levels is  not
achieved.
   Throughout  the  remediation process, innovative remediation technologies will  be considered
to enhance VOC mass removal and treatment of soil vapor, as discussed in Section 2.9.4.
   Once the ground water has reached cleanup levels, DOE, U.S. EPA, CVRWQCB, and DTSC
agree that:
   1)  It is not technically and economically feasible to operate the SVE beyond the point where
       the remaining  vadose zone VOC contaminants no longer cause the concentrations in  the
       leachate  to exceed the aquifer cleanup level; and
   2)  There is  relatively little benefit in continuing SVE because aquifer cleanup levels have
       been  achieved and  contaminants  in  the vadose zone will  not cause  contaminant
       concentrations in ground water to increase.

2.9.4. Innovative Technologies

   Innovative technologies that shorten cleanup time, improve cleanup efficiency, and reduce
cost  will continue  to be considered for application at the GSA throughout the remediation
process.   These technologies may be employed at the GSA if site  conditions change or
technology development and testing indicate a potential for cost-effective and  expedited
remediation. Innovative technologies will be employed with regulatory agency concurrence.
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2.9.5. Reporting

   Performance summaries for the ground water and soil vapor extraction and treatment systems
will be submitted to the U.S. EPA, DISC, and the CVRWQCB on a quarterly basis. A schedule
for submitting ground water and vadose  zone monitoring data and contaminant plume
concentration contour maps will be included in the remedial design document.

2.9.6. Summary of Preliminary Cost Estimates

   The 1995  present-worth cost of the selected remedy is estimated to be approximately
$18.90 million as  detailed in Table 10.  Many of the costs for technology development,
equipment purchases,  and facility construction associated  with  the implementation of the
selected remedy presented in Table 10 have already been incurred.  This cost estimate assumes
up to 10 years of SVE and monitoring,  up to 10 years of ground water extraction in the eastern
GSA, up to 55 years of ground water extraction in the central GSA, and up to 60 years of ground
water monitoring.  These time and cost estimates do not include the development, testing, or
implementation of innovative technologies.  Cost estimates and equipment may change as the
result of modifications during the remedial design and construction processes. Cleanup goals
and cleanup time estimates can be re-evaluated with the regulatory agencies every five years,
based on the effectiveness of the remediation system, changes in site conditions, and changes  in
regulatory requirements.

2.10. ARARs

   CERCLA Section  121 (d)(2)(A) requires that remedial actions meet any Federal  standards,
requirements, criteria, or limitations that are determined to be legally applicable or relevant and
appropriate. CERCLA Section 121 (d)(2)(A)(ii) requires that State ARARs be met if they are
more stringent than Federal requirements.
   There are three  general kinds of ARARs:
   1. Chemical-specific requirements  that define acceptable exposure concentrations or water
       quality standards,
   2.  Location-specific requirements  that may restrict remediation activities at  sensitive  or
       hazard-prone locations such as wildlife habitat and floodplains, and
   3. Action-specific requirements that may control activities and/or technologies.
   A list of potential ARARs related to the three proposed remedial alternatives was presented
in the GSA FS. ARARs directly related to the selected remedy is contained in Table 11 of this
ROD. These ARARs: 1) cite the most directly pertinent requirements related to specific actions
to be taken as part of the selected remedy, and 2) provide a mechanism for enforcement  of
standards  directly related to  the selected remedy (i.e., NPDES waste water discharge and air
discharge  permits).  When State ARARs are more stringent than Federal  requirements, only the
State ARAR is listed in the table.
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2.10.1. Chemical-Specific ARARs

   SWRCB Resolution 92-49 entitled "Policies and Procedures for Investigation and Cleanup
and Abatement of Discharges Under Water Code Section  13304" is a chemical-specific ARAR
for aquifer (ground water) remediation goals.  Resolution 92-49 provides general policies on
investigation, monitoring, and reporting.  All ground water cleanup activities associated with
implementation of the selected remedy for the GSA will be conducted under the supervision of
the CVRWQCB and in accordance with  Resolution 92-49.  In  addition, Resolution 92-49
authorizes the CVRWQCB to determine cleanup goals which must consider cost effectiveness
and technical feasibility.
   DOE, the U.S. EPA, State DISC, and CVRWQCB have agreed to a cleanup goal of drinking
water standards (MCLs) for VOCs in ground water in the  GSA OU, except as specified below.
This cleanup goal is  based on the chemical-specific  ARARs  (State and Federal MCLs)
established in the Federal Safe Drinking Water Act and California Safe Drinking Water Act.
The Federal and State MCLs for the chemicals of concern in ground water in the GSA OU are
given in Table 9.  The most stringent concentration limit, in most cases the State MCL, is the
governing ARAR for each chemical of concern and will be the cleanup goal for  ground water
remediation in the GSA.
   The CVRWQCB's  decision to concur with MCLs as ground water cleanup goals was based
on technical and economic information in the GSA FS. The CVRWQCB stated  "LLNL/DOE
presented  costs and time needed to cleanup to MCLs  and non-detect for TCE.  Based on
numerical  fate and transport modeling, LLNL/DOE showed that concentrations of TCE would be
below the  limit of detection (0.5 ppb [fig/L]) in all but a 12-acre area in  the vicinity of the GSA
after 55 years of pumping.   The 12-acre area  would  be below the MCLs, except for an
approximately 100 ft-square area at 5 to 10 ppb (Hg/L). Simulation TCE fate and transport for
an additional 35 years (without pumping) showed TCE contamination at or below  1 ppb (ng/L),
except for about a 100 ft-square area which would be at or below the MCL.  LLNL/DOE also
simulate 90 years of pumping, which showed that TCE  concentrations would be at or below
1 ppb (fig/L) in  all locations.  The Board agrees that  35 years  of additional  pumping for
achieving the small amount of mass removal is not economically feasible." However, if
remediation does not show that cleanup is proceeding as the modeling predicts, remediation
methods will be revisited.
   The CVRWQCB and the U.S. EPA do not concur with the selection of MCLs as the cleanup
goal  for chloroform and bromodichloromethane, because  the MCL for total trihalomethanes is
based on the economics of chlorinating a municipal water supply to remove pathogens and
therefore does not adequately protect the beneficial uses of a drinking water source that has not
been, and may not be, chlorinated.  The modeling as described in Appendix E of the  GSA
Feasibility Study predicts that TCE in the area where chloroform and bromodichloromethane are
found will be cleaned up to five to ten parts per billion (ppb) after 55 years of pumping.  The
agencies predict  that this  will result in cleanup of chloroform and bromodichloromethane to
1.1 ppb and 0.27 ppb, respectively. If the remediation does not show that cleanup  is proceeding
as predicted, the cleanup goals for chloroform and bromodichloromethane will be revisited,
following the procedure to be outlined in the GSA OU Compliance Monitoring and Contingency
Plan.
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   The CVRWQCB believes that the California Safe Drinking Water and Toxic Enforcement
Act of 1986, Health and Safety Code Section 25249.5 et seq. (Proposition 65) is an ARAR for
the establishment of in situ ground water cleanup levels. DOE has not included Proposition 65
as an ARAR in this ROD because federal agencies are exempt from its requirements (California
Health and Safety Code Section 25249.11).  The CVRWQCB will  not  dispute the ROD,
however, because the cleanup of the listed constituents will meet or exceed Proposition 65 levels.
   Because numerical standards or chemical-specific ARARs for cleanup of contaminants in
soil vapor have not been established, DOE and the regulatory agencies agreed upon a cleanup
goal for soil vapor which is protective of ground  water as discussed in Section 2.9.1.2.  The
objective is to reduce VOC mass in the vadose  zone to levels protective of ground water and
remediate VOCs in the vadose zone to the extent technically and  economically feasible  to
minimize further degradation of ground water by contaminants in  the vadose zone. DOE, U.S.
EPA,  and the  State disagree  on  the applicability  of SWRCB Resolution No. 92-49 and the
CVRWQCB's Water Quality Control Plan with respect to using water quality objectives  to
establish soil vapor cleanup levels.  The  State  concurs with this ROD, however, because it
believes that the standard in  Sections 2.9.1.2 and 2.9.3.2 complies with those requirements. This
ROD does not resolve the ARAR status of State requirements regarding the establishment of soil
cleanup levels.
   Chapter 15, CCR Title  23, Sections 2550.7 and 2550.10 are chemical-specific  ARARs,
which require the monitoring of the effectiveness of remedial actions. In accordance with these
ARARs, in situ concentrations of VOCs in ground water and soil vapor will be measured during
and after the completion of the selected remedy for the GSA OU to monitor its effectiveness in
achieving cleanup goals.
   State Board Resolution No. 88-63 (Sources of Drinking Water  Policy) designates all ground
and surface water of the State as drinking water except where the TDS is greater than 3,000 ppm,
the water source does not provide sufficient water to supply a single well more than 200 gallons
per day, the water is a geothermal resource or in  a waste water conveyance facility, or the water
cannot reasonably be treated for domestic use using either Best Management Practices or best
economically achievable treatment practices.
   Chemical-specific ARARs related to the discharges of waste resulting from remediation
activities include:  1) the SWRCB  Resolution 68-16, which is applicable to  the discharge  of
treated ground water from the remediation systems, and 2) the San Joaquin  Valley Unified Air
Pollution Control District (SJVUAPCD)  Rules 463.5  and  2201  regulating the discharge  of
treated vapor.  Treated ground water will be discharged according to the requirements of the
NPDES Permit (Order No. 91-052) for the eastern GSA and the Substantive Requirements for
the central GSA. These  permits are administered by the CVRWQCB.  The discharge standards
under the current permits require that the monthly  median VOC concentration in ground water
are reduced to below EPA Method detection limits for VOCs (<0.5 Hg/L),  prior to discharge.
Treated vapor will be discharged according to the requirements of the "Authority to Construct"
or "Permit to Operate" issued  by the SJVUAPCD,  which currently requires that VOC
concentrations in vapor be treated to 6 ppmv, prior to discharge to ambient atmosphere.
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2.10.2. Location-Specific ARARs

   Location-specific ARARs are restrictions placed on the concentration  of  chemicals or
conduct of operations based on the location of a site. Potential location-specific ARARs include
the protection of:
   •   Wetlands.
   •   Floodplains.
   •   Historic landmarks.
   •   Coastal zones.
   •   Coastal barriers.
   •   Rare and endangered species.
   •   Cultural resources.
   The GSA does not contain any historic landmarks, coastal zones, or coastal  barriers.  No
wetlands have been identified within the area of the GSA where the remedial action would occur.
Although  the GSA OU  is located adjacent to the 100-year floodplain associated with Corral
Hollow Creek, no portion of Site 300 lies within the floodplain. 22 CCR 66264.18(B)(1) states
that TSD  facilities within a 100-year floodplain must be designed, constructed, operated,  and
maintained  to prevent washout of any hazardous waste  by a 100-year flood.  If it became
necessary  to install POU treatment for water-supply well CON-1, which is located offsite within
the 100-year floodplain, the system would be constructed in accordance with this requirement.
   Archaeological and ecological surveys conducted in the GSA are described in Chapter 6 of
the SWRI and the Site 300 EIR/EIS (U.S. DOE, 1992), respectively.  Additional surveys to
identify potential cultural resources  and the presence of  sensitive (rare, threatened,  or
endangered) species will be conducted, as necessary, prior to all ground-breaking activities
associated with remediation in the GSA in order to mitigate any adverse impacts of the project.
In addition,  the discharge of treated water to Corral Hollow Creek that could affect endangered
species that may be in the California Department of Fish  and Game ecological preserve
downstream, is regulated through the NPDES permit for the eastern GSA treatment facility.

2.10.3. Action-Specific ARARs

   Action-specific ARARs are usually technology- or activity-based limitations on actions taken
with respect to hazardous wastes. These requirements are triggered by the particular remedial
activities  that are selected  to accomplish a remedy.  For the selected remedy, there are  two
action-specific ARARs which are related to:  1) monitoring of the reinjection of treated water,
and 2) the management of  hazardous wastes generated as a result of remedial activities.  All
treated water to be reinjected will be analyzed/monitored prior to reinjection in accordance with
the requirements of the Safe Drinking Water Act Underground Injection Control Program (40
CFR  144.26-144.27).  All  hazardous waste generated as the result of the selected remedy,
primarily  spent GAC, will be handled in accordance with the requirements of CCR, Title 22,
Chapter 30 and the Health and Safety Code, Sections 25100-25395.
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2.10.4. Other Applicable Standards

   There are no ARARs as cleanup standards for contaminants in the vadose zone that may
present an inhalation risk to human health. Therefore, a cumulative potential excess cancer risk
of 10"6 (one in one million) will be  used as the cleanup goal for mitigation of VOC inhalation
risk inside Building 875 as specified in the NCP (U.S. EPA,  1990a).
   As discussed in Section 2.11.2, the selected remedy meets ARARs by actively remediating
VOCs in soil and ground water to protect human health and the environment.

2.11. Statutory Determinations

   The selected  response  action for the GSA OU satisfies the mandates of CERCLA
Section 121. The remedy will:
   •   Protect human health by reducing risk from soil  vapor inhalation and by achieving
       ground water remediation goals.
   •   Comply with ARARs.
   •   Provide both short- and long-term effectiveness.
   •   Reduce contaminant toxicity,  mobility,  or volume as  a principal element.
   •   Be readily implementable.
   •   Provide the most cost-effective means of achieving remediation goals.
   DOE, U.S. EPA, CVRWQCB, and DTSC believe that  among the three proposed remedial
alternatives, Alternative 3b provides  the best balance of trade-offs with respect to the CERCLA
evaluation criteria.  Site 300 will remain under the control and ownership of DOE for the
foreseeable future. This is a major factor in defining the scope of the remedy proposed in this
ROD.  A brief description  of how the selected remedy satisfies each of these statutory
requirements, as well as state and community acceptance, is provided below.

2.11.1. Overall Protection of Human Health and the Environment

   The selected remedy uses exposure control methods, such as contingency POU treatment and
administrative controls, to provide initial protection to human  health. It also provides long-term
protection to human health by restoring and protecting the  beneficial use of the Tnbsj regional
aquifer and potential beneficial  use of the alluvial aquifer through active remediation to reduce
VOC concentrations in ground water  to MCLs.
   The selected remedy  prevents  potential  inhalation  of VOCs above health-based
concentrations in Building 875  by reducing soil vapor VOC  concentrations through soil vapor
extraction.
   All extracted soil vapor and  ground water will  be treated  before  discharge to the
environment.  Soil vapor and ground  water monitoring will document  the progress and
permanence of all remediation methods.
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   The selected remedy employs ecological surveys and  appropriate response actions, if
necessary, to protect the environment. By actively reducing VOC concentrations in soil vapor
and ground water, potential future ecological risks are mitigated.
   In accordance with a DOE Secretarial Policy issued in June 1994, National Environmental
Policy Act (NEPA) values contained in the Environmental Considerations chapter of the GSA
FS satisfy the requirements for CERCLA-NEPA integration. As part of these requirements, the
potential impacts on the existing onsite and offsite environment due to implementation of the
remedial alternatives were evaluated. No significant adverse impacts due to implementation of
the alternatives were identified.

2.11.2. Compliance with ARARs

   Federal and State chemical-, location-, and action-specific ARARs affecting the selected
remedy are described in Table 11.  The selected remedy meets all ARARs. Ground water and
soil vapor extraction will reduce VOC concentrations to MCLs in ground water in the GSA OU,
as well as reduce inhalation risk inside Building 875 to health-protective levels.

2.11.3. Short-Term Effectiveness

   The selected remedy  immediately protects the public from existing exposure pathways
through exposure controls: contingency POU treatment and administrative controls.  It also uses
ground  water  and soil vapor extraction to continue to remove VOC mass and  reduce VOC
concentrations in ground water and soil vapor. It provides measures for the protection of site
workers and the community during remedial actions.  No adverse environmental impacts are
anticipated.

2.11.4. Long-Term Effectiveness and  Utilization of Permanent Solutions

   The selected remedy provides long-term effectiveness through contaminant mass removal
that will:  1) reduce VOC concentrations to MCLs in  all affected ground water, and 2) reduce
VOC soil vapor concentrations to levels protective of ground water and to acceptable health
inhalation risk levels.  Monitoring will be continued for five years  after  discontinuing ground
water extraction to ensure  long-term effectiveness and permanence.

2.11.5. Reduction of Contaminant Toxicity, Mobility, or Volume as a
Principal Element

   Contaminant toxicity, mobility, and volume in the soil and ground water will be reduced
irreversibly by ground  water and soil vapor extraction.  In addition,  SVE will significantly
reduce  the toxicity,  mobility, and  volume  of both dissolved and undissolved (DNAPL)
contaminants in the subsurface, enhance the progress of VOC removal, and be more protective of
the environment than if only ground water extraction was used.
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2.11.6. Implementability

   The selected remedy can be readily implemented utilizing existing soil vapor and ground
water  extraction and treatment systems that  are permitted  and operating in the GSA.
Modifications to these systems are readily implementable.

2.11.7. Cost Effectiveness

   DOE, U.S. EPA, CVRWQCB, and DISC agree that Alternative 3b provides the most cost-
effective means of remediating VOCs in soil and ground water  to levels protective of human
health  and the  environment.  The cost  of this  alternative was estimated on the basis of a
preliminary engineering design to reduce inhalation risk, remove VOC mass, and reduce  VOC
concentrations in ground water to MCLs.

2.11.8. State Acceptance

   The California DTSC and CVRWQCB provided ARARs which were used as the basis for
developing the  selected remedy.  These State agencies reviewed and evaluated the remedial
technologies and alternatives and participated in the selection of the final remedy and provided
oversight and enforcement  of state environmental  regulations.  In addition, the regulatory
agencies have monitored and reviewed public acceptance of the final selected remedy.

2.11.9. Community Acceptance

   Public comments concerning the selected remedy have been considered and used, as
appropriate, in the preparation of this  ROD.   All public comments are addressed in the
Responsiveness Summary section of this document.
   Any proposed changes to the ROD, such as the implementation of new remedial alternatives
or innovative technologies, re-evaluation of the technical and economic feasibility of achieving
cleanup goals, etc., will be submitted  to the regulatory agencies for review and approval.
Community members will be informed of any ROD change, and would be provided with the
opportunity to comment on significant or fundamental ROD changes. Following EPA guidelines
(U.S. EPA, 1991), the lead agency determines if the proposed ROD change is: 1) nonsignificant
or minor, 2) significant, or 3) fundamental.
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 UCRl^AR-124061            Final ROD for the GSA Operable Unit, Site 300             January 1997
                  3.  Responsiveness Summary

    This section responds to public comments directed to DOE, LLNL, U.S. EPA, and the State
of California regarding the  Proposed Plan for remediation of the GSA OU.  Responses to
community comments and concerns are incorporated into this ROD.
    The public comment period on the Proposed Plan began April 10, 1996, and ended May 10,
1996.  On April 24, 1996, DOE/LLNL and the regulatory agencies held a public meeting at the
Tracy Inn in Tracy, California to present the proposed remediation plan and allow the public to
ask questions and comment on the preferred remedial alternative.  Representatives from LLNL
summarized the information presented in the FS and Proposed Plan.  Following the presentation,
three members of the public read their concerns  into the formal public record.  Although no
letters  were received during the Proposed Plan comment period, members of the Tri-Valley
Citizens Against a Radioactive Environment (CAREs) provided a written record of their meeting
comments. The meeting transcript and a copy of the written concerns are available to the public
at the LLNL Visitors Center and the Tracy Public Library.

3.1. Organization of the Responsiveness Summary

    This Responsiveness Summary is organized  to clearly present the breadth of public concerns
while minimizing repetition. In keeping with EPA Superfund guidance and accepted practice,
comments are grouped by subject.  Whenever possible, comments are summarized verbatim
from either the meeting transcript or written comments.
    Public comments are grouped into the following sections:

    •   Selected Remedial Action.

    •   General Comments.

3.2. Summary of Public Comments and Responses


3.2.1.  Selected Remedial Action

Comment 1:

    Before the Proposed Plan is approved, it is important that the monitoring plan be specified,
(number of wells, depth  of wells,  frequency of sampling, duration of sampling, approximate
location  of wells) and that a contingency plan be specified which delineates what the Lab is
committed to do should it find that the plume is moving, or is not being remediated in the time-
frame expected.  This should be similar in content to the way contingency was addressed in the
document entitled "Remedial Alternatives for the Building 815 Operable Unit. " There, specific
information regarding what  the Lab was prepared to do if the plume migrated past a certain
point was established.
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 UCRL-AR-124061            Final ROD for the GSA Operable Unit. Site 300             January 1997


 Response to Comment No. 1:

    A preliminary monitoring plan was presented in the FS to support cost estimates for each
 remedial alternative. This preliminary monitoring plan presented the number of wells and the
 frequency and duration of sampling. The depths and approximate locations of these wells were
 also included in the FS.  This information was not reiterated in the Proposed Plan, which is
 intended to be a brief summary document. Consistent with EPA  guidance and practice at other
 U.S. EPA Superfund sites, the GSA  monitoring program will be presented  in the Remedial
 Design document.  As specified in the  Site 300 FFA, a discussion of the schedule for the
 Remedial Design for the GSA will be  initiated within 15 days of the signing of the Final ROD,
 which is scheduled for January 1997.
    A formal review of remediation progress is required to be conducted at least every five years
 to ensure that the selected remedy is effective and continues to adequately protect human health
 and the environment.  However, the evaluation of the progress  of remediation  will be an on-
 going, continuous process.  Progress of site cleanup will be published in periodic  progress
 reports. If monitoring data indicate that the selected remedy is not effectively remediating the
 site, DOE/LLNL and the regulatory agencies will evaluate whether to consider another remedial
 alternative.

 Comment 2:

    The plan should contain milestones by which the success of the subsequent remediation can
 be evaluated. In almost all Superfund cleanup projects, commitments and milestones concerning
 the cleanup performance (e.g.,  timing  of cleanup, how much contaminant will be removed) are
 disregarded in Records of Decision.  We  regard  this as a fundamental problem with the
 government's approach to  CERCLA enforcement. For example, we suggest that a timetable for
 cleanup be established. This could be based on performance milestones such as the amount of
 contaminant mass that is removed from the soil and groundwater within an expected time period,
 and regulatory milestones such as achieving cleanup standards or showing  a  trend towards
 meeting cleanup standards.  This timetable would then be used to monitor the performance of
 cleanup, and provide interested parties with some idea how cleanup will progress. As it  now
 stands,  after a final ROD is signed, the only legal requirements are that substantial on-site
 remedial action be commenced within 15 months and that the cleanup program be subject to a
five-year review.  It is  important that the Proposed Plan contain a measurable schedule and
 performance standards which can be verified.

 Response to Comment No. 2:

    Consistent with  U.S. EPA Superfund guidance and as specified by the CERCLA process,
 schedules and performance milestones  will be presented in the GSA Remedial Design document.
 As specified in the Site 300  FFA, a discussion of the  schedule for the Remedial Design
 document for  the GSA will be initiated  within 15 days of the signing of the ROD,  which is
 scheduled for January 1997.
    DOE will  make the Remedial Design document available to the  public  as part of the
 CERCLA public participation process.  The public will  have an opportunity  to review and
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comment on the Remedial  Design document. If concerns or issues concerning the Remedial
Design  document  are identified on the part of the public and regulatory agencies, a public
meeting may be considered.
   The Remedial Design document will define in detail the technical parameters, design criteria
and components, and assumptions of the Remedial Action including:
    1.  Waste characterization,
   2.   Pretreatment requirements,
   3.   Volume and types of each medium requiring treatment,
   4.   Treatment schemes, rates, and required qualities of waste water streams,
   5.   Performance standards,
   6.   Long-term performance monitoring and O&M requirements,
   7.   Compliance with all ARARs, codes, and standards,
   8.   Technical factors of importance to the design and construction,
   9.   Construction schedule,
    10.  Cost estimates,
    11.  Variances with the ROD, if necessary,
    12.  Land acquisition and easement requirements, and
    13.  Value Engineering Screening (including an evaluation of cost and function relationships,
        concentrating on high-cost areas.
   The final Remedial Design must be approved by the regulatory agencies before initiating the
Remedial Action.  Cleanup standards are included in Section 2.9.1 of this ROD.
   A formal review of remediation progress is required to be conducted at least every five years
to ensure that the selected remedy is effective and continues to adequately protect human health
and the environment. However, the evaluation  of the progress of remediation will be an on-
going, continuous process.
   If the selected remedy fails to meet the criteria set forth in the design documents, DOE/LLNL
and the  regulatory agencies will evaluate whether to consider another remedial alternative.

Comment 3:
   I want to emphasize the need for contaminant reduction milestones as a  method of
determining not only how well  the cleanup is doing, but whether or not the cleanup's budget
year to year is sufficient.  Right  now, and this is a problem we are running into at the Main Site
to some extent, and in other sites as well, where the  milestones are defined as production of
documents, we are  going to have a remedial design document by thus and such a date or the
milestone is the putting in of  a  monitoring well or the construction of an extraction well
irrespective of whether those things alone.  Well obviously the production of the document
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 doesn 't actually remediate the site, irrespective of whether those things alone together are going
 to accomplish the cleanup and keep it on schedule.
    In saying you have a 55-year cleanup time, somebody has done a curve. I mean, you are
figuring you are going to peg down the contaminant levels by certain amounts to get to cleanup
 in 55 years.  If you made them explicit, that would give the citizens a way to track how the
 cleanup is doing, say,  in five-year increments and that the cleanup was falling behind, we would
 then have something we could use in saying our community needs some more money to get this
 back on track. None of us wants to wait 55 years, which means our children and in some cases
 our children's children will then say oh, that wasn 't enough, it isn 't cleaned up.
    So we really (the public) need this stuff to be codified in the Record of Decision to help watch
 dog and ensure a full  cleanup.  As Peter mentioned, mass removal milestones is another entree
 into the same type of result.

 Response to Comment No. 3:

    As stated in the response to Comment 2, schedules and performance milestones will be
 presented in  the  design document; consistent  with U.S. EPA Superfund guidance and as
 specified by the CERCLA process.   Budgetary  issues are discussed in the  response to
 Comment 17.
    The 55-year projected time to reduce VOC ground water concentrations in the central GSA
 to MCLs was based on remediation and contaminant fate and transport modeling presented in the
 GSA FS.  The modeling for the selected remedy (Alternative  3b) was discussed  in Section
 E-2.9.2.2 of the FS, and presented simulated  VOC ground water concentrations for  10, 30, 55,
 and 90 years after initiation of remediation.
    The modeling indicated that the selected  remedy utilized the optimum  number and
 configuration of extraction wells for the most cost- and time-effective remediation of the GSA.
 Although this modeling was conducted primarily for the purposes of determining cost,  it
 estimates remediation progress.  Additional modeling using current data may be  conducted
 during the five-year review to evaluate remediation progress.

 Comment 4:

    The Proposed Plan or the ROD should identify criteria it will use to determine whether a
 remedy should be replaced with a new remedy, or that remediation should be discontinued.  In
 the case of the former, there are many new development activities which may improve upon the
 selected remedy.  At some  time in the future there may be a decision to replace old technology.
 The (Proposed Plan) or the ROD should outline what decision criteria will be used to re-assess
 the proposed technology.  In addition, there has  been a trend at some sites to stop remediation
 on the grounds of "Technical Impracticability".   The (Proposed Plan) or the  ROD should
 outline the decision criteria  that would be  used to make such a  determination, as the decision
 will not be subject to the same level of public scrutiny as is the ROD.
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UCRL-AR-124061           Final ROD for the GSA Operable Unit, Site 300              January 1997
Response to Comment No. 4:

   The decision criteria that will be used to determine:
   1. When remediation should be discontinued are discussed in Section 2.9.3 of the ROD.
   2. Whether to replace the technologies outlined in the ROD are discussed in Section 2.9.4 of
       the ROD.

   3. When to cease remediation activities based on Technical Impracticability are discussed in
       Section 2.9.3 of the ROD.
   U.S.  EPA's OSWER Directive 9234.2-25, "Guidance for Evaluating the Technical
Impracticability of Ground Water Restoration" (EPA, 1993c), provides guidance for evaluating
Technical Impracticability. If the cleanup levels are changed due to Technical Impracticability,
an ARARs waiver will be obtained and a ROD amendment will be necessary.
   Throughout the remediation process, innovative remediation technologies will be considered
to enhance VOC mass removal and treatment of soil vapor, as discussed in Section 2.9.4.
   In addition, a review will be conducted every five years after commencement of the remedial
action to ensure that the remedy continues to provide adequate protection of human health and
the environment.

Comment 5:

   If the Proposed Plan could contain some more detail about the types  of treatment
technologies that are being considered, a little bit of data on the effectiveness of the treatment
technologies being used as pilot projects so that we could then discuss in greater detail, what
kind of suite of treatment technologies we might want to codify in the Record of Decision.  That
would make for a much higher sort of level of decision.

Response to Comment No. 5:

   The types of treatment technologies considered for implementation at the GSA, including the
technologies included in the selected remedy, were screened and discussed in detail in the GSA
FS. The  effectiveness of the existing treatment systems was also evaluated and discussed in the
GSA FS. The Proposed Plan is designed  to be a brief summary of the major components of the
evaluated alternatives and the preferred remedy that are discussed in detail in the FS.

Comment 6:

   The criteria for choosing treatment technologies need to be a part of the Record of Decision.
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UCRL-AR-124061            Final ROD for the GSA Operable Unit. Site 300             January 1997
Response to Comment No. 6:

   Consistent with U.S.  EPA Superfund guidance, the criteria  for  choosing treatment
technologies was presented in the GSA FS, where each treatment technology was screened and
discussed. See also response to Comment No. 3.

Comment 7:

   Remedial action objectives should be identified in the Proposed Plan and include:
   i)   Protect human  health  and ecological  receptors from contact with  contaminated
       groundwater, soil or air;
   ii)  Attain the preliminary remediation goals (PRGs) set by EPA Region 9.  (PRGs are
       remediation goals with an estimated health risk of one in one million additional cancer
       deaths);
   Hi) Conduct cleanup in such a way as to minimize time for remediation;
   iv) In the Central GSA, continue efforts to remove contaminant mass from the ground water
       and soil and locate the source of dense non-aqueous phase liquid (DNAPL).

Response to Comment No. 7:

   i)   Section 2.5  of the FS defines Remedial Action Objectives (RAOs) which are media-
       specific goals for protecting  human health and the environment.  EPA guidance indicates
       that RAOs are to specify exposure routes for which potentially unacceptable risk has
       been identified, contaminants of concern, and an acceptable contaminant concentration or
       range of concentrations. We have addressed these points in the RAOs. Cleanup goals
       are discussed in Chapter 4 of the FS and are specified in more detail in Section 2.9.1 of
       this ROD.
   ii)  The U.S. EPA, and the State DTSC, and CVRWQCB have concurred with a cleanup goal
       of MCLs  for VOCs in ground  water in the GSA OU. The CVRWQCB's decision to
       concur with  MCLs as ground water cleanup goals was based on technical and economic
       information  in the Final FS for the GSA OU.  The CVRWQCB stated "LLNL/DOE
       presented costs and  time needed to cleanup to MCLs and nondetectable for TCE. Based
       on  numerical fate and transport modeling, LLNL/DOE showed that concentrations of
       TCE would  be below the limit of detection (0.5 ppb [jig/L]) in all  but a 12-acre area in
       the vicinity of the GSA after 55 years of pumping. The 12-acre area would be below the
       MCLs, except for an approximately 100 ft-square area at 5 to 10 ppb (u.g/L).  Simulation
       TCE fate and transport for an additional 35 years (without pumping) showed TCE
       contamination at or below  1 ppb (^ig/L) except for about a 100 ft-square area, which
       would be  at  or below the MCL. LLNL/DOE also simulate 90 years of pumping, which
       showed that TCE concentrations would  be at or below  1 ppb (Hg/L) in all locations.  The
       Board agrees that 35 years of additional pumping for achieving the small amount of mass
       removal is not economically feasible.  However, LLNL/DOE will be required to review
       the remedial system every five years to determine if the remedial objectives are being
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       met.  LLNL/DOE will optimize the system or propose an alternative remedial method if
       the plume is not being remediated as projected."
       MCLs are health based and equivalent to an excess cancer risk of 10"6, or one in one
       million, with consideration given to technologic and economic factors.  U.S. EPA Region
       IX Preliminary Remediation Goals, according to EPA, "can be used as a rapid reference
       for  screening concentrations in environmental  media, as  'triggers'  for further
       investigation at CERCLA/RCRA sites, and as initial cleanup goals, if applicable."  The
       NCP (U.S. EPA, 1990a) states that "PRGs should be modified, as necessary, as more
       information  becomes available during the RI/FS.  Final remediation goals will be
       determined when  the  remedy is selected."   Remediation  goals are  developed by
       considering ARARs under Federal or State environmental laws. The NCP also states that
       the "10"6 risk level shall be used as the point-of-departure for determining remediation
       goals for alternatives when ARARs are not available."
   iii) The preferred remedy is designed to  achieve soil and ground water cleanup goals in a
       time-effective manner  using proven, implementable technologies. Other remediation
       scenarios were evaluated, such as installing more  wells to determine  if an increased
       ground water extraction  rate  would expedite cleanup.  Modeling  indicated that the
       selected remedy provided the most expeditious, cost-effective means of remediating the
       GSA OU.
   iv) The selected remedy  (Alternative  3b) includes both ground water and soil vapor
       extraction to remove contaminant  mass from ground water and soil in the central GSA.
       Based on historical and sampling data,  DNAPLs may be present in the vicinity of the
       Building 875 dry well pad where the SVE remediation efforts are concentrated.  The only
       wells in the  GSA  where ground water sample data indicate the possible presence of
       DNAPLs (TCE concentrations  >11,000 ppb) are wells W-875-07, -08,  -09, -10, -11, -15,
       and W-7I.  These wells  are all located in the Building 875 dry well pad area in the central
       GSA.  The source of DNAPLs in this area was the wastewater disposed in the two former
       dry wells, 875-S1 and 875-S2, located south of Building 875. No other wells in the GSA
       have contained VOCs in ground water in concentrations indicative of DNAPLs, including
       wells located at other source areas. We have therefore concluded that the DNAPLs are
       confined to the Building 875  dry well pad area in the central GSA.  SVE has been
       identified as a technology that can effectively remediate DNAPLs in the vadose zone.
       Throughout the life of the remediation project, continued efforts will be made to evaluate
       whether DNAPLs  act as a continuing source of contamination.  The  methodology and
       schedule  for the evaluation of DNAPLs will be included in the remedial  design
       document. The objective of these  investigations is to validate whether the assessment of
       the location of DNAPLs, as well as efforts to remediate DNAPLs, are properly focused.

Comment 8:

   The Proposed Plan should include a continued search for the location of DNAPLs in the
central GSA, and the testing and/or development of new technologies to extract DNAPL, until
monitoring conclusively proves that they are no longer present in  the area. It does not appear
that the DNAPL problem will be solved by the Proposed Plan.  Without removal of DNAPL, the
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site will act as a continuing source of contamination, and may reverse the progress that has been
made in cleanup over the past several years.  While DNAPL or potential DNAPL exists at many
sites that I am aware of, solutions are elusive without knowing the precise location. I suggest the
(Proposed Plan) identify how many quarters (or years) that monitoring will be required to show
that DNAPLs are no longer present.

Response to Comment No. 8:

    As discussed in Chapters 1  and 4 of the FS, residual DNAPLs may exist in soil in the
dewatered zone and/or vadose zone in the central GSA in the vicinity of the Building 875 dry
well pad, as discussed in the response to Comment No. 7 (iv). Data from other nearby wells and
wells in other source areas allows us to conclude that DNAPLs are confined to the Building 875
dry well area.
    The preferred remedy (Alternative 3b) includes  SVE, which has been  identified  as  a
technology that can effectively remediate DNAPLs  in the vadose zone (U.S. EPA, 1992d,
1993b).  Historical sampling data indicate that DNAPLs may be in the vicinity of the
Building 875 dry well pad where the SVE remediation efforts are concentrated.  Ground water,
soil, and soil vapor data collected from other release areas do not indicate that DNAPLs are
present. DOE/LLNL will continue to investigate and evaluate innovative technologies that  may
be considered for application at the GSA if they could  be implemented cost effectively and
expedite remediation. Throughout the life of the remediation project, continued efforts will be
made to evaluate  whether DNAPLs  act as  a continuing source of contamination.   The
methodology and schedule for the evaluation of DNAPLs will be included in the remedial design
document.  The objective of these investigations is to validate whether the assessment of the
location of DNAPLs, as well as efforts to remediate DNAPLs, are properly focused.
    In general, if a ground water VOC concentration is 1 to 10% of the solubility of that VOC in
ground water, then a DNAPL may be present.  Because the aqueous solubility of  TCE  is
1,100,000 |ig/L, TCE concentrations in the range of 11,000 to 110,000 \iglL or greater would
indicate DNAPL. The cleanup goals established for ground water (i.e., 5 fig/L for TCE) are well
below the  concentrations  indicative  of DNAPLs (11,000 \ngfL for TCE).   When VOC
concentrations in ground water have been reduced to cleanup goals (MCLs), the ground water
extraction and treatment system(s) will be shut off and placed on stand-by.  Modeling indicates
that VOC concentrations in ground water in the central GSA should be reduced to MCLs within
55 years following the initiation of remediation.  Ground water in the central GSA will continue
to be monitored for a period of five years following shutdown of the system.  This will allow
tracking of ground water VOC concentration trends in the Building  875 dry well pad area  to
determine if:  1) ground water VOC concentrations in the area indicate DNAPLs, and 2) the
ground water remediation goal has been attained and maintained. Should VOC concentrations  in
ground water "rebound" or increase above cleanup goals,  reinitiation of remediation efforts will
be discussed with the regulatory agencies.

Comment 9:

    I am concerned on a number of levels.  One of them, let me just  use as an example the
problem with dense non-aqueous phase liquids with the concentrations of TCE that you have at


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 UCRL-AR-124061            Final ROD for the GSA Operable Unit, Site 300             January 1997


 Site 300, there probably are globs of pure TCE in there and as those dissolve over time it is
 going to continue as its own source of contamination and in order to get at those, you guys need
 money for something called source investigation.  John Ziagos will remember I am big on
 advocating money for source investigation to make sure that you have got the information you
 need so that you put in the right cleanup technologies in the right places to actually achieve a
 cleanup.  I think it's penny wise  and pound foolish to neglect source investigation, so I am
 looking at the Department of Energy's fiscal year 1998 draft priority list and for the one that's
for the Livermore Lab Main Site and Site 300. The first time I see source investigation, let me
just say for the record, this line here is put at a target of what is gonna be 19.4 million dollars
 they plan to ask for for FY1998 and everything that falls below this line they are not even gonna
 ask for money for and the first time source investigation is mentioned is about ten listings below
 the line.  So, there is not even any consideration  that DOE is going to even ask for money that
 will adequately fund source investigation in the time frame when you are really gonna need that
 money.  So codifying something in the'Record of Decision is a way to ensure that that gets
 bumped up, because then it becomes a legal requirement and it suddenly is part of what becomes
 necessary and not optional and in my opinion, some of these things, I mean, all of these that I am
 talking about are necessary.
    So then I looked at how it rates in the field office where the lab has to compete against the
 other DOE facilities and its four from the bottom  on page 5. So if it isn 't codified in the Record
 of Decision, I kind of think that you are probably not gonna get the money to do it and you are
 going to have ongoing problems that will threaten the entire cleanup because there is not the
 money to go out and do the source investigation  needed to fund the DNAPLs and also some of
 the other important parameters before cleanup can be accomplished.

 Response to Comment No. 9:

    Based on historical sampling data described in the response to Comment No. 7 (iv) and our
 extensive source investigations presented in the SWRI and FS, we have concluded that DNAPLs
 are confined to the Building 875 dry well pad area in the central GSA. The  source of potential
 DNAPLs in this area was the wastewater disposed in the two former dry  wells  875-S1 and
 875-S2 located south of Building 875.  No other wells in the GSA have contained VOCs in
 ground water indicative of the presence of DNAPLs.  Because the source of the DNAPLs has
 been confirmed as the two former dry wells 875-S1 and 875-S2, located south of Building 875,
 and analytical data confirms that the DNAPLs are confined to the vicinity of the Building 875
 dry well  pad, no additional source  investigation for DNAPLs in  the GSA is planned at this time.
 TCE concentrations in ground water in GSA monitor wells will be monitored  throughout the life
 of remediation. If future ground water analytic data indicate that DNAPLs have migrated or are
 present in  other  areas  of the  GSA, changes to  the remediation  system(s) to  address  the
 presence/remediation of DNAPLs will be considered at that time.
    Throughout the life of the  remediation project, continued efforts will be made to evaluate
 whether  DNAPLs act as a continuing source of contamination.  The methodology and schedule
 for the evaluation of DNAPLs will be included in the remedial design document.  The objective
 of these investigations is to validate whether the assessment of the location of DNAPLs, as well
 as efforts to remediate DNAPLs, are properly focused.
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Comment 10:

    I think essentially the points that both Peter Strauss and Marylia Kelly have made about
looking for these DNAPLs, as they are called, looking for the source of contamination which
obviously  could have an impact on the cleanup and how fast or how easy it would be to achieve
certain milestones, which I do believe should be in place, are critical.

Response to Comment No. 10:

    See responses to Comments Nos. 7 (iv) and 9. The potential presence of DNAPLs in the
central GSA was factored into the ground water modeling conducted for the selected remedy.
This modeling was the basis for estimating cleanup time for the selected remedy.

Comment 11:

    The Lab must demonstrate that natural attenuation is actually occurring at this OU.  At the
main site,  early modeling factored in natural attenuation to calculate cleanup time. A later study
invalidated  this assumption.  There has not been,  to the best  of my  knowledge, conclusive
evidence that natural attenuation is a relevant factor in the cleanup ofTCE at Site 300, although
models on the length of time for cleanup may use this assumption.  For example, vinyl chloride is
a natural  breakdown product ofTCE.  TCE has been found at extremely high concentrations in
the GSA, yet the baseline health risk assessment does not include an assessment of vinyl chloride
because it has not been found at Site 300. Vinyl chloride is a known human carcinogen, and is
harmful at very low concentrations,  i.e., 0.5 ppb is the  drinking water standard for vinyl
chloride.

Response to Comment No. 11:

    The selected remedy (Alternative 3b) does not rely on natural attenuation as a component of
the remediation of soil or ground water in the GSA. This remedy provides for active remediation
to reduce  VOC concentrations in soil and ground water to levels protective of human health and
the environment.

Comment 12:

    Something that our  group, working  with a  hydrologist, took a look at for the Main Site
cleanup which you will recall, John Ziagos, but I would like to see you folks take a crack at this
for the GSA  and that is taking a look at, okay, you have a cost estimate in present dollars. What
percentage  of that is your capital costs and what percentage is M&O costs?  How many
extraction wells, etc. do you plan to put in? How many could you put in optimally and if so, how
would that cut down on  your 55-year cleanup time and, therefore, perhaps really cut down on
the amount  of cost for the cleanup overall?  If it became a 30-year cleanup with some more
extraction wells instead  of a 55-year  cleanup, perhaps the overall cost would go down
dramatically.  I suspect that that's true. Again, this is information, that if it were discussed and
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 analyzed in your documents, you could pick up some allies in the citizens groups in terms of
 helping implement what DOE calls the accelerated cleanup.

 Response to Comment No. 12:

    Capital costs represent 18% of the total cost for implementing the selected remedy, while the
 operation and maintenance (O&M) costs  are 30% of the  total.  The other 52% consists of
 monitoring  and contingency (POU treatment,  etc.) costs. These percentages for the proposed
 alternatives, as well as the selected remedy, are  shown in Figure 5-1 of the FS.
    The number of extraction wells proposed for the selected remedy is discussed in Section 2.9
 of this ROD. The number and location of these extraction  wells were based on modeling that
 was used, in part, to determine the optimum configuration and number of extraction wells for the
 most cost- and  time-effective removal of VOCs from the GSA.  The modeling indicated that
 increasing the number of extraction wells, from the number currently  proposed, would not
 significantly decrease cleanup  time.  However,  these modeling data will be evaluated and
 incorporated into the final design presented in the Remedial Design document. Data obtained
 from future well installation may allow DOE/LLNL to optimize wellfield performance.

 Comment 13:

    I wanted just to emphasize a little bit aside from agreeing on the need for real milestones in
 achievement in  cleanup which should be built in,  I am particularly concerned about the
 budgetary aspects of this, and it occurred to me also that, as Marylia Kelly pointed out, really 3b
 was the only truly legal alternative and I am very pleased that the lab is, you know, proceeding
forth on that track; but, if you were to consider alternatives among legal alternatives, you might
 be  looking at alternatives with different time schedules and that, of course, also may have
 different budget schedules, you know, the 55-year schedule versus a 30-year or whatever and
 what different amount of technology that needs  to be put in at the front end of that and what kind
 of schedule you have.

 Response to Comment No. 13:

    As part of the modeling conducted to estimate cleanup times, various numbers of extraction
 wells were evaluated to estimate the optimum  configuration and number of extraction wells to
 achieve the  most  time- and cost-effective cleanup of the GSA. The optimum configuration and
 number  was included in the  ground water  extraction component  of  the selected remedy
 (Alternative 3b).  The modeling indicated that by increasing the number of extraction wells from
 that presented in the selected remedy, the time  and cost  of cleanup were  not significantly
 decreased.  Numerous remedial technologies were evaluated and screened as part of the GSA FS.
 The technologies in  the selected remedy represent the best available technologies, given site
 conditions, currently available.  DOE/LLNL will continue to  evaluate innovative technologies
 for possible use in the GSA if innovative technologies will expedite site cleanup and/or be more
 cost effective.
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Comment 14:

   The cleanup standards for TCE and other VOCs should be more stringent.  Because the GSA
connects with the regional aquifer, we believe that the cleanup standard should be set at the
incremental lifetime cancer risk (ILCR) of one in one million (1 x 10~^).  CERCLA guidelines
require cleanup to I x 1&-4 to 1 x 1Q-6 ILCR.  The Preliminary Remediation Goal (PRG)for
TCE is the most current attempt to define the 1 x 1Q-6 cleanup standard.  The PRG for TCE is
1.8 ppb.  We believe that PRGs should be adopted for VOCs that can migrate to the regional
aquifer.  I note that at two other Superfund sites where I serve as the Technical Advisor, the
PRPs (in one case a private party, in another the DoD and the City of Tucson) have adopted a
cleanup standard based on reducing risk to one in one million.  Thus, it is clear that EPA and
responsible parties can adopt these stricter standards.

Response to Comment No. 14:

   The U.S. EPA, and the State DISC, and CVRWQCB have concurred with a cleanup goal of
MCLs for VOCs in ground water in the GSA OU. The CVRWQCB's decision to concur with
MCLs as ground water cleanup goals was based on technical and economic information in the
Final FS for the GSA OU. The CVRWQCB stated "LLNL/DOE presented costs and time
needed to clean up to MCLs and non-detectable TCE.  Based on  numerical fate and transport
modeling, LLNL/DOE showed that concentrations of TCE would be below the limit of detection
(0.5 ppb [^g/L]) in all but a 12-acre area in the vicinity of the GSA after 55 years of pumping.
The 12-acre area would be below the MCLs, except for an approximately 100 ft-square area at 5
to 10 ppb (|ig/L).   Simulation TCE fate and transport for an additional 35 years (without
pumping) showed TCE contamination at or below 1 ppb (^ig/L) except for about a 100 ft-square
area, which would be at  or below the MCL. LLNL/DOE also simulate 90 years of pumping,
which showed that TCE concentrations would be at or below 1 ppb (Hg/L) in all locations. The
Board agrees that 35 years of additional pumping  for achieving the small amount of mass
removal is not economically feasible.  However,  LLNL/DOE will be required  to review the
remedial system every five years to determine  if the remedial objectives are being met.
LLNL/DOE will  optimize the system or propose an alternative remedial method if the plume is
not being remediated as projected."
   MCLs are health based and equivalent to an excess cancer risk of 10-6, or one in one million,
with consideration given to technologic and economic factors.  U.S. EPA Region IX Preliminary
Remediation Goals, according  to EPA, "can be used as a rapid reference for screening
concentrations  in environmental media, as 'triggers' for further investigation at CERCLA/RCRA
sites, and as initial cleanup goals, if applicable."  The NCP (U.S. EPA, 1990a) states that "PRGs
should be modified, as  necessary,  as more information becomes available during the RI/FS.
Final remediation goals will be determined when the remedy is selected." Remediation goals are
developed by considering ARARs under Federal or  State environmental laws. The NCP also
states that the "10~6 risk level shall be used as the point-of-departure for determining remediation
goals for alternatives when ARARs are not available."
l-97/124061:GSAROD:rtd                      3-12

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UCRL-AR-124061           Final ROD for the GSA Operable Unit. Site 300             January 1997
3.2.2. General Comments


Comment 15:

   Also, as a general comment, I would like to say that for each of the areas of Site 300,  the
DOE and the lab and the regulators would do well to interface with the DOE folks who  are
preparing the waste management programmatic environmental impact statement which gives as
one of the potential alternatives, the burial of large amounts of ash from mixed waste and low
level radioactive waste at Site 300 and how that potential burial of waste would impact  the
cleanup is something that they didn 't look at in the waste management PEIS and that was one of
our comments on that, but it's also something that you then can't incorporate in talking about
the cleanup of these various operable units because, in fact, they didn't even mention where they
planned to dump it at Site 300.  So for each of these, that is a question for you guys to ask and
get some clarification, and if you don't think dumping a lot of radioactive and still possibly toxic
ash is going to aid the cleanup, you might have some allies in the citizens group on that.

Response to Comment No. 15:

   Comment noted.

Comment 16:

   One last overarching issue,  and there is no delicate way to bring it up so I will just bring it
up bluntly.  Our group is really concerned about some of the changes that are being considered
in the Superfund laws and in particular, some of the changes that would affect the Livermore  lab
cleanup wherein if the state standard was stricter than the federal standard, the federal standard
would become the only thing that the lab  would have  to clean up to.   There  are a number of
areas where the Regional Water Quality Control Board and the state DTSC have stricter
standards than the federal EPA  and achieving those standards is an important part of achieving
an actual cleanup and so what I think should be investigated is the extent to which writing those
things in the Record of Decision will be one way of protecting against having  the standards be
lowered  as the  cleanup goes on,   and as we  all know, once  the  standards  change,  the
Departments of Energy's  target changes and so that target, in  terms of how clean is clean and
what they think they need to clean  up to  is in danger of becoming lower and lower and the
Record of Decision is the method that I see to ensure that today's cleanup standards are  the
cleanup standard's that are met.

Response to Comment No. 16:

   If Federal or State regulations were to change in the future, DOE and the regulatory agencies
would discuss how these changes might affect cleanup.  The community would be informed of
any regulatory changes that affect cleanup at Site 300. Any proposed changes to the ROD must
be submitted to the regulatory  agencies for review and approval.  Following EPA guidelines
(U.S. EPA, 1991), the lead agency determines if the proposed ROD change is:  1) nonsignificant
1-97/12406 l:GSAROD:rtd                       3-13

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 UCRL-AR-124061            Final ROD for The GSA Operable Unit, Site 300              January 1997


 or minor, 2) significant, or 3) fundamental.  Community members would be informed of any
 ROD change, and would be provided with the opportunity to comment on significant  or
 fundamental ROD changes.

 Comment 17:

    Our group has talked a number of times of the need for stable long-term funding and budget
 commitments. Having some kind of budget schedule for the preferred alternative and any other
 alternative time scenarios would be very useful for citizens to be able to monitor the commitment
 of the DOE and the lab to the cleanup as well as in combination with achievement milestones
 and whether they are on track with that, whether the funding is adequate and so 7 would argue
for some kind of additional information to be included on the budgetary aspect over time.

 Response to Comment No. 17:

   DOE cannot legally commit to funding cleanup or any other activities beyond the current
 budget year appropriation. However, DOE places a high priority on risk reduction, compliance,
 and associated environmental cleanup in its  annual budget submittals.  DOE understands that
 cleanup  delays will likely increase the  overall cost of the  LLNL cleanup as well as other
 facilities, so it is in DOE's best interest to support an adequately funded and progressive cleanup
 effort through its annual Congressional budget request each year. DOE does commit to request
 from Congress, through the Office of Management and Budget, funding necessary to control and
 remediate contaminant plumes, both on  and offsite.  In addition, DOE is also committed  to
 removing contaminants as efficiently as possible using available technologies within budgeting
 allocations.
 l-97/124061:GSAROD:rtd                      3-14

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References

-------
UCRL-AR-124061              Final ROD for the GSA Operable Unit, Site 300          January 1997
                                 References

Anspaugh, L. R.,  J. H. Shinn, P. L. Phelps and N.  C. Kennedy (1915), "Resuspension and
   Redistribution of Plutonium in Soils." Health Phys. 29.
California Environmental Protection Agency (Cal-EPA) (1992), Memorandum from Standards and
   Criteria Work Group to California EPA Departments, Boards, and Offices regarding California
   Cancer Potency Factors, dated June 18, 1992.
Hwang, S. T., J.  W. Falco, and C. H.  Nauman  (1986), Development of Advisory Levels for
   Poly chlorinated Biphenyls (PCBs) Cleanup, Office of Health and Environmental Assessment,
   Exposure  Assessment  Group, U.S.  Environmental Protection Agency, Washington,  D.C.
   (PB86-232774).
McKone, T.  E. (1992), Environmental  Engineer, Lawrence Livermore National Laboratory,
   Livermore, Calif., personal communication with Linda Hall.
NRC  (1994), Alternatives for Ground Water Cleanup,  National Research Council, National
   Academy  Press, Washington, D.C.
Rueth, L. S., and T. Berry (1995), Final Feasibility Study for the General Services Area Operable
   Unit,  Lawrence  Livermore National Laboratory Site 300,  Lawrence  Livermore National
   Laboratory, Livermore, Calif. (UCRL-AR-113860).
Turner, D. B. (1982), Workbook of Atmospheric Dispersion Estimates, Office of Air Programs,
   U.S. Environmental Protection Agency, Research Triangle Park, N.C.,  TD-18/Office of Air
   Program Publication No. AP-26.
U.S.  DOE (1992),  Environmental Impact  Statement and  Environmental  Impact Report for
   Continued Operation of Lawrence  Livermore National Laboratory and Sandia National
   Laboratories, Lawrence Livermore National Laboratory, Livermore, Calif., U.S. Department
   of Energy, Washington, D.C. (DOE/EIS-0157).
U.S. DOE/LLNL (1996), The Proposed Plan for Remediation of the Lawrence Livermore National
   Laboratory Site  300 General Services  Area, Lawrence Livermore  National Laboratory,
   Livermore, Calif. (UCRL-AR-122585).
U.S. EPA (1989a), Risk Assessment Guidance for Superfund, Vol. I:  Human Health Evaluation
   Manual, Interim  Final, Office of Emergency and Remedial  Response,  U.S. Environmental
   Protection Agency, Washington, D.C. (EPA/540/1-89/002).
U.S. EPA (1989b), Risk Assessment Guidance for Superfund, Vol. II:  Human Health Evaluation
   Manual, Interim  Final, Office of Emergency and Remedial  Response,  U.S. Environmental
   Protection Agency, Washington, D.C. (EPA/540/1-89/001).
U.S. EPA (1990a),  "National Oil and Hazardous Substances Pollution Contingency Plan,  Final
   Rule," U.S.  Environmental Protection Agency, Washington, D.C. (40 CFR Part 300), Fed.
   Re gist. 55(46), pp. 8666-8865.
U.S.  EPA  (1990b),  Exposure  Factors  Handbook,  Office  of Health  and Environmental
   Assessment, U.S. Environmental Protection Agency, Washington,  D.C. (EPA 600-8-89-043).
                                         R-l

-------
UCRL-AR-124061              Final ROD for the GSA Operable Unit, Site 300          January 1997


U.S. EPA  (1991), Risk Assessment Guidance for Superfund, Vol. I:  Human Health Evaluation
   Manual, Supplemental Guidance—"Standard Default Exposure Factors," Interim Final, Office
   of Emergency and  Remedial  Response, Toxics  Integration Branch, U.S.  Environmental
   Protection Agency, Washington, D.C. (OSWER Directive: 9285.6-03).
U.S. EPA (1992a), Health Effects Summary Tables, Supplement No. 2 to the March 1992 Annual
   Update, Office of Research and Development, Office of Emergency and Remedial Response,
   U.S. Environmental Protection Agency, Washington, D.C. (OERR 9200.6-303 [92-3]).
U.S. EPA  (1992b), Integrated Risk Information System-IRIS, an electronic database maintained
   by  the U.S.  Environmental Protection Agency,  Office of Research  and Development,
   Environmental Criteria and Assessment Office, Cincinnati, Ohio.
U.S. EPA (1992c), Health Effects Assessment Summary Tables, FY-J992 Annual, Office of
   Research  and  Development,  Office   of  Emergency  and  Remedial  Response,  U.S.
   Environmental Protection Agency, Washington, D.C. (OHEA ECAO-CIN-821).
U.S. EPA (1992d), Dense Nonaqueous Phase Liquids—A Workshop Summary, Dallas, Texas,
   April 16-18,  1991, Office of Research and  Development, U.S.  Environmental Protection
   Agency, Washington, D.C. (EPA/600/R-92/030).
U.S. EPA (1993a), Memorandum from D. Stralka, Ph.D., U.S. Environmental Protection Agency
   Region DC, to L.  Tan,  Remedial Project Manager, U.S. Environmental Protection Agency
   Region IX, regarding a 'Technical request from Linda Hall at Lawrence Livermore National
   Laboratory" for toxicity values for PCE, TCE, and tetrahydrofuran, dated February 25, 1993.
U.S. EPA (1993b),  Seminar on Characterizing and  Remediating Dense Nonaqueous Phase
   Liquids at Hazardous Sites, Office of Research  and Development, U.S.  Environmental
   Protection Agency, Cincinnati, Ohio (EPA/600/K-93/003).
U.S. EPA (1993c),  Guidance for Evaluating  the Technical Impracticability  of Ground Water
   Restoration,  Interim Final,  Office of Solid  Waste  and  Emergency  Response,  U.S.
   Environmental Protection Agency, Washington, D.C. (OSWER Directive 9234.2-25).
Webster-Scholten, C.  P., Ed. (1994), Final Site-Wide Remedial Investigation  Report, Lawrence
   Livermore  National Laboratory  Site   300,  Lawrence  Livermore National   Laboratory,
   Livermore, Calif.  (UCRL-AR-21010).
Wilson, J. L., and P. J. Miller (1978), 'Two-Dimensional Plume in  Uniform Ground-Water
   Flow," Journal of the Hydraulics Division, Proceedings of the American Society  of Civil
   Engineers, 104(HY4), pp. 503-514.
                                         R-2

-------
Figures

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
1997
          Miles
   0   5   10  15  20
ERD-GSA-ROO-0001
Figure 1.  Locations of LLNL Livermore Site and Site 300.

-------
UCRL-AR-J2406J
Final ROD for the GSA Operable Unit, Site 300
1997
                                                                 Site 300 boundary
           Legend
          General Services
          Area Operable Unit

          Road

        Scale: Feet
    0      2000    4000
                                        General Services
                                        Area Operable
                                        Unit
ERO-GSA-ROO-0002
Figure 2. Location of the General Services Area OU at LLNL Site 300.

-------
   t
    Legend

'Fault; arrows show
relative sense of
vertical offset

Water Table
Qt-Tnsc1
  hydro-
geologic
    unft
                                                                       Sewage treatment
                                                                       pond     Water
                                                                                      Qal-Tmss
                                                                                      hydrogeologic unit
                                                                                             Low permeability
                                                                                             sedimentary rock
                                                                                             (Tmss)
                                                                                                                                c:
                                                                                                                                §

                                                                                                                                50

                                                                                                                                §
                                                                                                                        l
                                                                                                                                 Co
                                                                                                                                 5?'
                                                                                                            Not to scale
          EHD-QSA-ROO-0003
 Rgure 3. Conceptual hydrogeologic model of the General Services Area.

-------
  '•""   871.-
  \	
                                      Steam-cleaning/
                                      sink facility

                                            \
    ' x    - Corp  i
   '/ ..••'•'  yard  j
/ /_A     storage!
                       874
Decommissioned        ;'-•-""'—IT""""""
solvent drum rack     /,'•'''.'••	^r    :
and solvent        /''/'  Sewage
retention tank   ..-//  j  treatment
                     /      pond '.;.-•"""
                                        Former dry wells
                                                                                                                  Scale : feet
                                                                                                                0     125    250

                                                                                                                                          §
                                                                                      i
ERO-GSA-flOO-OCXM
Figure 4. Confirmed chemical release sites in the central GSA.

-------
UCRL-AR-I24061
Final ROD for the GSA Operable Unit. Site 300
1997
         Scale : feet
       0     125    250
                       Site 300
                                Site 300
                              boundary
                                                             I'.-
      Debris burial
           trench
                           Debris burial
                            trench area
                                                         I//
                                                    //   .
                                                    *• •••     /
                                              /:<••
                                                                      Connolly
                                                                       Ranch
                                                   -California Department
                                                    of Forestry
     Corral ^

ERO-GSA-ROO-0005
                                      Sewage
                                      treatment
                                      pond
Figure 5. Confirmed chemical release sites in the eastern GSA.

-------
 .rJtTW-875-08
*V  .  .-•   Drv
           Dry
               W-875-09
               Dry
              Scale : feet
            0      25      50
                       S«wtg* treatment pond
 Inset map of dry well pad wells
             W-35A-08
              <0.5
                                                   W-35A-14
                                                    <0.5
ERO-GSA-ROO-0006
                             OillO-2
                                                                                                         Legend

                                                                                             -•V-  Monitor well completed In the Qt-Tnsc,
                                                                                                 hydrogeologic unit with TCE
                                                                                                 concentration In i
oaiio-2
Inactive water-supply well
Inferred ground water TCE
isoconcentration contour (ng/L), dashed
where uncertain, queried where unknown
      Scale : feet
    0     100    200
                                                                                                                                         s
                                                                                                                                          if
                                                                                                                                          £
                                                                                                                                          2
                                                   I
Figure 6. TCE concentrations in ground water from the shallow aquifer (Qt-Tnsc,) in the central GSA (4th quarter 1995 data).

-------
-4- W-7C
    
ERCM3SA-ROO-OOU
Figure 7. TCE concentrations in ground water from the Tnbs1 regional aquifer in the central GSA (4th quarter 1995 data).

-------
7.1
        legend
Monitor well computed to (iluvtaVshaUm
bedrock equder ihoielngioul VOC
concentration (yoAJ
       -•-      Monitor well completed In the deiper
     •KOMI    bedrock equtfer thowMg total VOC
      (<•>)     concentration bioA.).O«a not used In
               conlourlno.
               Tool VOC concdMnilon contour
               OiyLK da*n*d ntxr* uncwuln,
               qtMrtod «rtt«f* unknown
                                                                                                                               I
                                                                                                                               I

Flgun S. ToUl VOC conc.nl/itlont In ground w*Ur In lh« tlluvluni (Qtl) -ind tUllow bMlroek (Tnb»,) In th» «ajtern CSA (4th qjartor        §
199SHIU).                                                            I                                                        ~J

-------
                      Legend

             Monitor well completed in the Tntas,
             hydrogeologlc unit (regional aquifer)
             with TCE concentration In ug/L
             Active water-supply well

             Inactive water-supply well

             Inferred ground water TCE
             isoconcentratlon contour (fig/L), dashed
             where uncertain, queried where unknown
       1.5
  W-26R-07

  \  18
 W-26R-01
  \\
   <0.5
W-26R-02
                                       Sewage trealmenl pond
                                                                       <0.5
                                                                    W-25N-10
                                                                     W-25N-13
                                                                        <0.5
                                                                                    I
                                                                                    I
                                                                                                                                            >3


                                                                                                                                            §
                                                                                    I



                                                                                    t


                                                                                    I
                                               Ccllfoml* Department
                                               of Forestry Fir*
                                               Department
                                                                                          <0.5
                                                                                          W-25N-25
ERD-GSA-ROD-0009
Figure 9. TCE concentrations in ground water from the deeper Tnbs1 regional aquifer in the eastern GSA (4th quarter 1995 data)

-------
UCRL-AR-12406I
Final ROD for the GSA Operable Unit, Site 300
1997
Base from U.S. Geological Survey.
Midway 7.5' quadrangle, 1953, photorevised, 1980.
Tracy 7.5' quadrangle. 1954, photoreviaed, 1981.
                    2/5
                                         1 MILE
ERD-GSA-R OO-O010
                   Scale
                                         Legend

                            CDF-1 "4"  Active water-supply well
                            —-——  Site 300 property boundary
                                       Ground surface elevation
                                C 900 1ft above MSL)
                                       Contour Interval: 100 ft
Figure 10. Locations of active water-supply wells.

-------
 VCM^Ut-IHMI
                                                                                           final KODforttu CM O>» mMr (/«/( fil, JOfl
                Ugand

           :  bdtUng wall lo ba uaad lor
             alluvial aqulfM ground watar
             attraction. Wall W-I76-OI
             alto lo ta* uMd lo aitracl
             aoll vapor.
    W.Jf •$•* EiliUng mil lo b* HMd lor
             Tnlii, r»fllon
-------
                                                                                                                         r-
                                                                                                                         i.
  +
  O
  24
                     Legend
                     eoinpM
           bedrock equMer showing lotslVOC
           Monitor well completed In the de«p«f
           beilroi*.*^ snowing tot* VOC
           canoMlrallenbignj.O«t«noluMdln
«£
  ^
 /
           Aettv««nMr-«upply«nU

           Spring
           TOM VOC eofmntntlon contour
           tiiQAJ, Omn*S ohtra uncvtaln,
           quwtod wtor* unknown
                  Seal*: !••!
                0     290    500
                   pond
                                                                                                                         §
                                                                                                                         |
                                                        CalHomU DopuUMM ot Fonwliy
Rgur* 12. Total VOC concentrations In ground inter In th* •lluvlum (Oil) and •hallow bedrock (Tnb«,) In the ••stem GSA (4th quartor
1991 data).

-------
    <0.5
    W-TD
   COM


   CON-2
         Legend

Monitor well completed In the Tnbsj
hydrogeologlc unit (regional aquifer)
with TCE concentration In ng/L

Active water-supply well

Inactive water-supply well

Inferred ground water TCE
Isoconcentratlon contour (ng/L), dashed
where uncertain, queried where unknown
                                                               15
                                                          W-26R-07

                                                          \ 71
                                                        W-26R-01
                                                          \\
                                                          <0.5
                                                       W-26H-02
                                                     W-TD   A_
                                                       '   <0.5  ,,
                                                       W-26N-10 »-W-2SN-11
                                                        W-25N-13   <0.5
                                                           <0.5   r—I
                                                                           to -*-
-------
                                                              Water treatment
                                                           (Aqueous phase GAC)
                                                                                               Discharge
                                                                                               of treated
                                                                                               ground water
                                                                                               to Corral
                                                                                               Hollow Creek
   Extracted
ground water
                                                                    Ground water
                                                                    extraction well*
                                                                                                                           §
                                                                                                                           g
                                                                                                                           f
                                                                                                                           i.
                                                                                                                           Ui
                                                                                                                           §
CRO-OM-AQO-OOtt
Figure 14. Schematic of the eastern GSA remediation system for the selected remedy (Alternative 3b).

-------
Approx. local
    of dry t
  875-S1, 87
 Inset map of dry well pad wells
                                                                   I

                         W-873-02
                              22
<0.5+
 W-35A-02
ERD-QSA-ROtMMU
                              Gallo-2
                                                                                         w"70
                                                                                        « .. ,
                                                                                        Gallo-2
                                                                                         /
             Legend
  Monitor well completed in the Qt-Tnsc,
  hydrogeologlc unit with TCE
  concentration In jig/L
i-  Inactive water-supply well
   Inferred ground water TCE
   isoconcentratlon contour (ng/L), dashed
   where uncertain, queried where unknown
 Note:  Data shown for Building 875 dry
       wells Is for 1st quarter 1992
            Scale : feet
         o      100     200
                                                                                                                                          §
                                                                                                                                         >
                                                                                                                                          3-
                                                                                                                                          <»
                                                                                                                                          §
                                                                                                                                         f
                                                                                                                                          I
                                                                                                                                          to
Figure 15. TCE concentrations in ground water from the shallow aquifer (Qt-Tnsc^ In the central GSA (4th quarter 1991 data)
                                                                                                                                          58

-------
             Legend
i w 7C    Monitor well completed
< 0.5
 m
               Tnbs, hydrogeologlc
          unit with TCE
          concentration In ng/L.
          Data in parenthesis (<0.5)
          not used In contouring.
          Inferred ground water
          TCE isoconcentration
          contour (tig/L), dashed
          where uncertain, queried
          where unknown.
           Scale : feet
        o     100     200
                                                                                                                                     Jo

                                                                                                                                        §
                                                                                                                                        1
                                                                                                                                        o-
                                                                                                                                        s-
                                                                                                                                        §
  ERD-GSA.ROD-0007
  Figure 16. TCE concentrations in ground water from the Tnbs1 regional aquifer in the central GSA (4th quarter 1991 data).

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                                                                    Vapor treatment (GAC)*
                                                                                                       Discharge of
                                                                                                       treated vapor
vapor from
air stripper
                                         Discharge
                                          of treated
                                    ground water to
                                     ground surface
              Vapor treatment (GAC)
                                 Water
                             treatment
                            (air stripper
                            oraqueous*
                            phase GAC)
               Extracted
               soil vapor

   Vacuum pump        ,  •
                     around water and soil
                     vapor extraction wtdls
                                          Extracted
                                       ground water
 Ground water
extraction well
                                                   Ciaystofteaquftard
                                                                                 c:
                                                                                 Q
                                                                                 r-
                                                                                 i.
                                                                                 5
                                                                                 5"
                                                                                                                                       i
                                                                                 I
                         Treatment of vapor from ground water treatment system Is not necessary if aqueous-phase GAC is used.
ERD-OU.ROO-OOt)
Figure 17. Schematic of the central GSA remediation system for the selected remedy (Alternative 3b).

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Tables

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 1.  Contaminants of potential concern in ground water in the GSA.
Contaminant
Central GSA
1,1,1-trichloroe thane
1,1 -dichloroethylene
cis-l,2-dichloroethylenec
Acetone
Benzene
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Trichlorofluoromethane (Freon 113)
Eastern GSA
1,1,1-trichloroe thane
1,1 -dichloroethylene
l,2-dichloroethylenec
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Maximum
concentration9

2.0 x 103
4.0 x 103
1.0 x 103
8.2 x 10°
5.0 x 10ld
3.3 x 10°
7.4 x 10°
2.5 x 104
2.4 x 10s
1.6 x 102

9.4 x 101
5.0 x KT1
6.0 x 10-1
3.3 x 10°
1.4 x 101
4.4 x 10°
6.1 x 101
Mean
concentration*'''

2.93 x ItT1
7.37 x KT1
2.56 x 10°
4.08 x 10°

4.05 x 1(T2
6.10 x 10-1
3.89 x 101
8.30 x 102
1.07 x 101

2.93 x KT1
4.30 x KT1
4.27 xHT1
4.05 x 10~2
9.60 x 10-1
1.32 x 10°
2.66 x 101
95% UCLa

1.62 x 10°
1.18 x 10°
3.75 x 10°
5.78 x 10°

6.62 x lO-2
8.98 x lO"1
7.73 x 101
3.09 x 103
1.89 x 101

1.62 x 10°
4.45 x ID"1
4.41 x ir1
6.62 x ID*2
4.25 x 10°
1.64 x 10°
3.39 x 101
a  All units are in Mg/L.
"  Estimate of the arithmetic mean of the underlying log normal distribution.
c  The chemical 1,2-dichloroethylene (1,2-DCE) exists as two isomers, cis-l,2-DCE and trans-l,2-DCE. At various
   times throughout the nine years of ground water analysis at Site 300, this chemical has been analyzed for as
   1,2-DCE (total), as one or both of the specific isomers, or as all three. When concentration data were available
   for one or both isomers, we used those values and omitted the less specific analysis for total 1,2-DCE from
   further consideration. The exceptions to this were in cases where the concentration reported for total 1,2-DCE
   was greater than that reported for one or both isomers.
"  The value given for benzene is the maximum measured concentration for this chemical in ground water in the
   central GSA. This maxima was reported from the last quarter of sampling data included in the SWRI database
   (first quarter, 1992) (Webster-Scholton, 1994), and came from the vicinity of the Building 875 former dry wells.
   A mean concentration and a 95% Upper Confidence Limit (UCL) were not calculated.
1/97/12406 l:GSAROD:rtd
                   T-l

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UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 2.  Contaminants of potential concern in surface soil (<0.5 ft) in the GSA.
Contaminant
1,1,1-trichIoroethane
Acetone
Cadmium
Chloroform
Copper
HMX
Tetrachloroethylene
Toluene
Trichloroethylene
Trichlorofluoromethane (Freon 113)
Trichlorotrifluoroethane (Freon 11)
Xylenes (total isomers)
Zinc
Maximum
concentration9
5.0 x 10~3
6.0 x NT2
1.6 xlO1
3.0 x ID"4
3.4 x 102
2.0 x NT2
S.OxlO-2
6.0 x 10~3
8.4 x 10~2
1.3 x 10~2
7.9 xlO-2
7.0 xlO-3
8.3 x 102
Mean
concentration*'*'
6.85 x 10-4
3 39 x 10~2
6.43 x 10°
3.82 x 10"4
3.94 x 101
NAC
1.61 x 10~3
1.30 x 10~3
3.75 x 1CT3
1.00 x 10~3
1.23 x 1(T2
1.47 x 10~3
2.06 x 102
95% UCLa
1.86 x l
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
January
Table 3.  Contaminants of potential concern in subsurface soil (>0.5-12.0 ft) in the GSA.
Operable unit
region
Building 875

Debris burial
trenches


Contaminant
1,1,1-trichloroethane
1,1-dichloroethylene
cis-l,2-dichloroethylene
Chloroform
Tetrachloroethylene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 11)
Chloroform
Methylene chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Trichlorofluoromethane
(Freon 113)
Trichlorotrifluoroethane
(Freon 11)
Maximum
concentration9
1.0 x Iff"2
5.0 x NT4
3.0 x 10-4
3.0 x 10-4
1.0 x 10-1
5.4 x 10-1
6.0 x ID"2
4J x ID-2
1.4 x 10-2
8.8 X lO-3
5.0 x 10~3
2.4 x 10-2
3 .3 X lO-3
4.0 x 10-4
Mean
concentration3'**
2.13 x 10~3
NCC
1.88 x ID"4
1.88 x 10-*
3.28 x 10~2
1.74 x ID"1
8.03 x ID"3
1.47 x ID"3
4.26 x KT4
1.95 x 10-3
2.73 x 1C-3
2.43 x ID-3
1.34 x 10-4
1.20 x 10-4
95% UCLa
4.38 x 10-3
5.0 x 10-*c
2.96 X lO"4
2.96 x Itr4
7.54 x ID"2
4.14 x 10-1
1.87 x ID"2
3.35 x ID-3
1.74 X ID"3
4.32 X ID"3
3.14 x ID"3
4.31 x ID"3
3.95 X ID"4
1.67 X 10-4
a  Units are mg/kg.
"  Estimate of the arithmetic mean of the underlying log normal distribution.
c  NC = Not calculated. For certain data sets, calculation of a UCL yielded a value greater than the
   maximum measured concentration (Webster-Scholten, 1994, Appendix P). In those instances, a mean
   concentration was not calculated, and the maximum concentration is given instead of a UCL.
1/97/124061 :GSA ROD:rtd
                  T-3

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 4. Contaminants of potential concern in VOC soil flux in the GSA.
Contaminant
Central GSA
1,2,4-trimethylbenzene
1,3,5-trimethylbenzene
Benzene
Methylene chloride
Toluene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Eastern GSA
1,1/1-trichloroe thane
1,2,4-trichlorobenzene
Dichlorodifluoromethane
(Freon 12)
Methylene chloride
Styrene
Toluene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Building 875 dry well area
1,2,4-trimethylbenzene
Chloromethane
Dichlorodifluoromethane
(Freon 12)
Ethylbenzene
Methylene chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Limit
of detection
(mg/m2*s)

1.05 x 10-*
1.10 x 10-*
6.79 x 10~7
9.50 x 1(T7
8.01 x 1(T7
1.13 x KT6
1.70 x 10"6

9.58 x ID"7
9.58 x 10-7

1.18 x 10-6
1.09 x 10-*
1.09 x 10-6

8.67 xlO-7
9.07 xl(T7
8.34 x 10~7
1.18 x 10-6
1.77 x 10~5

9.98 x 10~7
9.98 x 1(T7

1.09 x lO"6
4.63 x l
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 4.  (Continued)

Contaminant
Building 875 dry well area
(Continued)
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Limit
of detection
(mg/m2»s)

1.82 x KT6

9.98 x Itr7
9.98 x l
-------
                                                                              Final ROD for ike CM Operable Vnlt, Site MO
                                                                                                                                                                                   January 1997
PtfUrt (flitene) fat; CMftvrfwuw hoof If ntutftrnM all fartltlei
  ri.«- —1..-.--1 -  -
                                                                                                                                         MI..M«..(.)    Confld.nc.Umll     conc.nlr.Hoiu
                         	        i  «n*t pamftff
D.U mduiled >m from mirf.c* Mill iample«   Mau-Ioading (Anipaugh .1.1,1975).
coliKted throughout th« OU
                                                                                                                 1,1,1-trichloro.lhaiw
                                                                                                                 Action.
                                                                                                                 Cadmium
                                                                                                                 Chloroform
                                                                                                                                      Kmgftg*
                                                                                                                                      O0003 mg/kg*
«dlKtadaraagh*
                    UlxlO-'mg/m1*
 9JImg«g*
 O000873 mg/kg*
 SCJmgftg*
 WBmgAg*
 OAnsSmg/kg*
 OJXQSCmg/kg*
 04118 rag/kg*
 000219 mg/kg*

00384 mg/kg*

0X1034 mg/kg*
362 mg/kg*
 OODUCmg/kg*     LWx 10-* mg/kg*
 0049mg«g*      4^xlO->mg/kg*
 9 Jl mg/kg*        9JlxlO°mg/kg*
 0000675 mg/kg*    8.75 X 10~* mg/kg*
 56J mg/kg*        S47X101 mg/kg*
 O02mg/kg*        iJOO x 10-1 mg/kg*
 000358 mg/kg*     3.58 xlO-1 mg/kg*
 oomacmgflig*     racxio^mgflig*
 OOllBmg/kg*      U*xUT*mg/kg*
 00019 mg/kg*

0X081 mg/kg*

00034 mg/kg*
                            T-6
               3J4xlO-* mg/kg*

               3^0x10-* mg/kg*
               3«x«r»mgfl(g*

-------

UCKL-AX-IH062
Table S. (Continued)



Final HOD for the GSA Operable Unit. Site 300



Media/process
release area(s)
Model and/or method

Potential eiposure polnt(s)
Chemicals of concern
Maximum
concentration at
release areafs)

95% Upper
Confidence Limit
January 1991
Estimated exposure-
point
concentrations
VtlatUivUion of contaminant! from lukiurfoc* toil Into air wilk'ui a building
Immediate vicinity of Building 875.






















Volatilization of contaminants from
subsurface soil and diffusion of VOCs
through concrete Into a building. VOCs
(McKonel992).









Inside Building 875






















1,1-dlchloroelhylene
l.M-trichooroe thane
Benzene
Chloroform
cls-U-diehloroethylene
Mithylene chloride
Tetrachlonethylene
Trichloroethylene
Trlchlorofluoromethane
(Freonll)
Trlchlorotrifluoroethane
(FreonlU)
0X005 mg/kg*
OOlmg/kg'
OXOSmg/kgC
0X032 tag/kg*
OXlmg/kg*
00013 mg/kg«
aiing/kg*
0.75mg/kg<
0X016 mg/kg<

OX«mgftg<

OOOOlUmg/kg*
000286 mgftg<
0000917 mg/kg*
0X0199 mg/kg<
0X0317 mg/kg<
0000612 mg/kg<
0X697 mg/kg1
0596mg/kg<
0X016 Dig/kg*

0X209 Big/kg'

2J9xlO-«mj/m3b
L23xlO-*mg/mIb
169x10-* mg/orlb
5.71xl(r5mg/m5b
3^2xlO-»mg/mJb
I55xl0-*mgtalb
1.10xlO-» mg/mjl>
UaxlO-Jmg/m»'
2J3xlO-tmg/m3b

5.63 x 10-> mg/m3b

fr '—"=[—'~ -frrir' — *i — t/Tii r-frr/ — "" ** **" -*— p*—
Potential releases la the vldnlly of the debris
buial trench.

— — -





feafociurffnuiufiMi


«s>imi





Ur (Central GSA)
Building 875 dry well area, solvent drum rack
area. Building 879 steam cleaning/sink area.
Volatilization of contaminants from soil to
air (Hwang et al, 1986); air dispersion
(Tomer, 19J2).
. . • • •
^** — •* •






Wilson and Miller (1978) mathematical
ground water model.
Building 872 dry well. Building 874 dry well.
Building 873 dry well considered it a tingle
release.

In the vidnlty of the debris burial trench.


















Ground water from the Qt-Tnsci
hydrogeologlc unit. Assumes undiluted
transport of VOCs from Building 875 area
to the Site 300 boundary. Model Is used to
simulate the transport of TCE through the
alluvium to well CDF-1.
Chloroform
Methylene chloride
Tetradudocoethyiene
Toluene
Trichloroethyiene
Trichlorofluoromethane
(Freonll)
Trichlorotriflaoroethane
(FrwnlU)

Primarily
trlchloroethylene;
co-conlamlnants detected
In ground water samples In
the study area also
considered.
OJOOmsfktf
Oj014mg/kg<
00068 mg/kg<
OXOSmgykg<
0X024 mg*g<
0X033 mg/kg«
a0004mg/kg<



240X00 jlg/L«d





0X0335 mg/kg*
0X0174 mg/kg*
0X0432 rngfltg1
0X0314 mgft*/
OXObtnng/kg1
0X00395 ing/kg*
0X00167 mg/kg<



35^40 (uj/L* at site
boundary

Assumed
modeling source
term Is 1X00 flg/L
U5xlO-*mg/Bin>
«J3xlO-»«»/m*
lUxlO-^Bij/or*
UlxlO->ngnan>
L24xlO-»mg/nr">
7Xlxl(TsmgAnsb
$J3 x MT* mgAn^b



35^49 ugrt.^

SJSjig/L4^



T-7

-------
                                                                                                                                          1:
UCRL-M-114062


Tables. (Continued)
                                                                                    Final KOD/onht GSA Opttabk Unit, Silt 300
                                                                                                                                                      January 1997
               Medla/pnxee*
               relea** araa<»)
         Modal and/or method
                                               Potential expomir* polntit)
                                           Chemluli of concern
                                                                     Maximum                        Estimated expoeur*-
                                                                   concentration at      95% Upper            point
                                                                    release area(a)    Confidence Limit     concentration*
StUfntk «WfraW m*r (Bourn GSA)

  Oebrii burial trenches.
PLUME analytical ground water model.
  Available data throughout the OU conaidered  FS, Section 15J (Ruelh and Beery, 1995)
  (Section LU).
Alluvial ground water. Assumes transport   Primarily
of VOC* from release alle to the Site 300     Mddomthrlene;
boundary and CDF area. Modal Is used to   co-contaminant* detected
almulate the transport of TCE through the   In ground water (ample* In
alluvium to aheep ranch well SR-1.         the study are also
                                        considered.
General area of OU and vicinity of debris    Primarily TCE, PCE.
burial trenches. (Exposure pathway*
discussed In Section 15J of the FS)
                                                                  aug/lTCE"!
                                                                                                                                                                      modeling (oarc*
                                                                                                         FS, Section tSJ.   FS, Section 1JJ.    FS, Section 1JJ.
  Surface aolL
  Ali.
  rndkted auxboiui 70-vear average TCB coot.ntr.don and «|>o>ure?a|jit toix.nlr.llon at the Site MO boundary.
  Predicted i-r-*~"~ TD-yeat avenge TCB cont.ntr.aon and me eipoenre-peuit cont.ntr.tlon In ground water pumped (ram CDF-I.
  Predicted maxtmua 70-year average TCB concentration and the estimated eipowre-polnl concentration In ground water at the eastern CS A (awurnlng no plume commingling).
          I •uxtaua TD-year averafe TCE concentration and eetlauled eiposure-polnt comentralim at well SR-1.
Noleo
        mlOfnai per nbk metu;

        •dcncm per Ulei.
                                                                                                                                                                   T-8

-------
Table 6. Cancer risk and hazard index summary, and reference list for the GSA OU.
Potential
exposure pathway
Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the Building 875 dry well area in the central GSA
(AOS exposure)

Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the central GSA (AOS exposure)


Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the eastern GSA (AOS exposure)


Inhalation of VOCs that volatilize from subsurface soil into the
indoor air of Building 875 in the central GSA (AOS exposure)



Potential AOS exposure to contaminants in surface soil (0 to
0.5 ft) in the GSA for:

a) inhalation of particulates resuspended from surface soil, and
b) ingestion and dermal adsorption to surface soil

Additive incremental
excess lifetime Additive
cancer risk estimate hazard index
2 x 1(T7 6.2 x 10~3



7 x 1(T7 1.2 x 10~3



2 x 10~7 1.3 x 10~3



1 x 10~5 3.0 x 10-1







a) 2 X ID"7 a) 5 6 x 10-5
b) 2 x 1(T10 b) 8.5 x 1(T3

References for related tables
in supporting documents
FS:
Tables 1-28
1-31
1-34
FS:
Tables 1-29
1-32
1-35
FS:
Tables 1-30
1-33
1-36
SWRI (Chapter 6):
Table 6-51
Appendix P
Tables P-27-6.1
P-27-6.10
FS:
Table 1-25
SWRI (Appendix P):
Tables P-27-6
a) P-27-6.11
b) P-27-6.12
1
r-
1






5
!
o
§
*»
Ci
B
t
1
5"
c:
a
£
1





-------
Table 6.  (Continued)
Potential
exposure pathway
Adult Onsite Exposure in the GSA



Potential residential exposure to contaminated ground water
that originates in the GSA at:
a) Central GSA site boundary
b) Eastern GSA site boundary
c) Well CDF-1
d) Well SR-1

•


Additive incremental
excess lifetime
cancer risk estimate
9xlO~7





a) 7xl(T2
b) 5xl(T5
c)lxlO~5
d) 2 x 10~5




Additive
hazard index
9.8 x HP3





a) 5.6 x 102
b) 5.0 x 10-1
c) 1.4 x 10-1
d) 1.6 x 10"1




Location of related tables in
supporting documents
FS:
Table 1-37
SWRI (Chapter 6):
Table 6-55
FS:
Table 1-26
SWRI (Appendix P):
Tables P-27-6.5
P-27-6.6
P-27-6.7
P-27-6.8
P-27-6.13
P-27-6.14
P-27-6.15
P-27-6.16
Notes:
   AOS = Adult Onsite.
     FS = Final Feasibility Study for the General Services Area, LLNL Site 300 (Rueth and Berry, 1995).
   GSA = General Services Area.
  SWRI = Final Site-Wide Remedial Investigation Report, LLNL Site 300 (Webster-Scholten, 1994).
   VOC = Volatile Organic Compound.

                                                                                                                                              §
                                                                                                                                              g
                                                                                                                                              I
Oj
 '

-------
UCRL-AR-124061
   Final ROD for the CSA Operable Unit, Site 300
January 1997
Table 7. Summary of GSA OU remedial alternatives.
Alternative 1: No action
Alternative!: Exposure
control
Alternative 3a: Remediation
and protection of the Tnbsj
regional aquifer
•   Monitoring
    —  Quarterly water level measurements of monitor wells and
       supply wells.
    —  Periodic ground water sampling and analysis of monitor wells
       and supply wells.
    —  QA/QC samples.
•   Administrative controls
    —  Fencing and warning signs around site.
    —  Full-time security guards on site.
•   Continued ecological surveys.
•   Other
    —  Well and pump maintenance.
    —  Reporting.
    —  Project management.
    —  Database management
    —  QA/QC review.
Modeled project life: 80 years of ground water monitoring to reach
MCLs.	
All elements of Alternative 1 plus:
•   Contingency POU treatment
—  Install and operate POU GAC treatment system for offsite water-
    supply wells CDF-1, CON-1, and SR-1 if VOC concentrations
    exceed MCLs.
Modeled project life: 80 years of ground water monitoring to reach
MCLs.	
AH elements of Alternative 2 plus:
•   Ground water extraction well installation
    —  Install four new ground water extraction wells.
    —  Convert six existing monitor wells to ground water extraction
       wells and one to an injection well.
•   Ground water extraction and treatment
    —  Extract ground water from 20 extraction wells (19 shallow
       alluvial, 1 Tnbsi regional) and reinject into 1 well (Tnbsi
       regional).
    —  Install new ground water treatment systems using air stripping,
       VOC adsorption, and/or other appropriate technologies.
       Design capacity would be approximately 15+ gpm at the central
       GSA and 46-t- gpm at the eastern GSA.
    —  Extract ground water from Tnbsi regional aquifer until VOC
       concentrations reach MCLs.
    —  Extract ground water from the alluvial aquifer until ground
       water VOC concentrations are reduced to levels protective of
       the Tnbsi regional aquifer (approximately 100
 1-97/124061 :GSAROD:rtd
                    T-ll

-------
UCRL-AR-124061
   Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 7. (Continued)
                            •  Soil vapor extraction (SVE) and treatment
                               —  SVE from seven existing wells.
                               —  SVE and treatment using existing system until vapor
                                   concentrations reach levels that prevent recontamination of
                                   ground water above MCLs, and to reduce inhalation risk in
                                   Building 875.
                            •  Other
                               —  Permitting.
                               —  Ground water treatment system and SVE system maintenance.
                            Project life: 10 years of SVE, 10 years of ground water extraction and
                            treatment at the eastern GSA and 30 years at the central GSA, and
                            70 years of ground water monitoring to reach MCLs.
Alternative 3b: Ground
water plume remediation
All elements of Alternative 3a plus:
•  Continued ground water extraction and treatment at the central
   GSA until ground water VOC concentrations are reduced to MCLs.
Project life: 10 years of SVE, 10 years of ground water extraction and
treatment at the eastern GSA and 55 years at the central GSA, and
60 years of ground water monitoring to reach MCLs.
l-97/12406l:GSAROD:nd
                    T-12

-------
Table 8. Comparative evaluation of remedial alternatives for the GSA OU.
Alternative
Alternative 1
No action
Overall protection
of human health and
environment
Human health:
No
Environment: No
Compliance
with ARARs
Criterion may
be metc
Short-term
effectiveness
Protective of site workers
and the community during
monitoring by preventing
potential exposure through
the use of administrative
controls and/or use of
protective equipment.
Ground water and air risks
not addressed.
Long-term
effectiveness and
permanence
Not effective.
Reduction in
contaminant volume,
toxicity, and mobility
Dependent on
natural attenuation
and degradation.
Implementability
Implementable
Costa-b
3.47
                                                                                                                                      I
                                                                                                                                      E
                                                                                                                                      so
Alternative 2
Exposure
control
Human health:
Air    No
Ground water
       Yesd
Environment:  No
Criterion may
be metc
Alternative 3a  Human health:
Remediation   Air    Yes
and           Ground water Yes
protection of
the regional    Environment:  Yes
aquifer
                    Criterion may
                    be met
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment
Addresses ground water
risk with POU treatment at
existing water-supply
wells. Does not address air
risk.
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment
Addresses site risks with
active remediation of soil
and ground water.
Effective for ground
water risks at existing
water-supply wells.
Not effective for long-
term reduction of VOC
mass or air risk.
                       Dependent on
                       natural attenuation
                       and degradation.
Implementable     3.69
                                                                                                                                                    1
                                                                                                                                                   •§
                                                                                                                                                    f
                                                                                                                                                    ?'
                                                                                                                                                    J/J
                                                                                                                                                    «r
                                                                                                                                                    1
Effective for air and
ground water risks in
the Tnbsi aquifer.
May not be effective for
ground water risk in
shallow aquifer in the
central GSA.
Ground water and soil
vapor extraction
increases source
removal effectiveness.
                                                              Reduction in shallow
                                                              unsaturated zone,
                                                              and shallow and deep
                                           Implementable     17.17
                                                                                  contamination;
                                                                                  partially dependent
                                                                                  on natural
                                                                                  attenuation and
                                                                                  degradation.

-------
Tables.  (Continued)
Alternative
Alternative
3b
Ground water
and soil
remediation
of both
shallow and
regional
aquifers


Overall protection
of human health and Compliance
environment with ARARs
Human health: Criterion met
Air Yes
Ground water Yes
Environment: Yes






Short-term
effectiveness
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment.
Addresses site risks with
active remediation of soil
and ground water.
Long-term
effectiveness and
permanence
Effective for air and
ground water risks.
Ground water and soil
vapor extraction
address all soil and
ground water
contamination.




Reduction in
contaminant volume,
toxicity, and mobility Implementability
Reduction in shallow Implementable
unsaturated zone,
and shallow and deep
aquifer
contamination.






Costa-b
18.90









   Estimated tola] present worth in millions of 1995 dollars. Overall cost is highly dependent on the required length of pumping time.
   The estimated costs for all alternatives presented in this ROD are slightly lower than the costs presented in the GSA FS and PP. This is due to modifications to the
   1) contingency POU treatment component based on negotiations with the well owner, and 2) ground water monitoring component based on changes made to the eastern and
   central GSA treatment facility permit monitoring program requirements.
   Relies solely on natural attenuation and degradation to comply with Safe Drinking Water Act, Basin Plan, and State Resolutions 68-16 and 92-49.
   Protective of human health for ingestion of ground water from existing water-supply wells.

I
g
                                                                                                                                                                   I
                                                                                                                                                                   Jo
                                                                                                                                                                   ST
                                                                                                                                                                   I
                                                                                                                                                                   58

-------
UCRL-AR-124061                 Final ROD for the GSA Operable Unit, Site 300             January 1997
Table 9. Chemical-specific ARARs for potential chemicals of concern in ground water at the
GSA OU.
Chemical of concern
1,1,1-trichloroethane
1,1-dichloroethylene
cis-l,2-dichloroethylene
Benzene
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Cancer
group"
D
C
D
A
B2
B2
B2-C
B2-C
Federal MCL

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
        January 1997
    Table 10. Selected remedy (Alternative 3b): Capital costs for source mass removal and
    plume migration prevention in the GSA OU.
                                                                           Unit price    Total
    	Quantity  Unit type    (1995$)    (1995$)

                                           Capital costs
                                            Central GSA
    Ground water and soil vapor extraction system major
    equipment costs (MEC)
    Wellhead vaults, valves, sampling ports, gauges
    Additional wellhead vaults, valves, sampling ports,
    gauges
    Electrical line and conduit
    2-in. polyvinyl chloride (PVC) piping
    Electric submersible pumps (1 /2 horse power [hp])
    Additional electric submersible pumps (1/2 hp)
    PVC pipe fittings, unistrut
    SVE blower system (5 hp)
    SVE pitot tubes, vacuum gauges, sampling ports
                      7 previously installed

                          10       each         1,500     15,000
                        1,200      foot          1.75      2,100
                        1,200      foot          1.50      1,800
                      10 previously installed
                          10       each           800      8,000
                          1         lot         10,000     10,000
                          1        each         2,000      2,000
                      Previously installed
    SVE treatment MEC
    Moisture accumulation assembly, carbon canister
    hookup
    Vapor-phase carbon canisters (1,000 Ib)
    SVE manifold, piping
                     Previously installed
                          3        each
                     Previously installed
 6,000      18,000
    Ground water treatment MEC
    Particulate filter assembly
    Low-profile tray air stripper (includes blower and
    transfer pumps, total of 7 hp)
    Carbon dioxide injection equipment
    Discharge storage tank (20,000 gal.)
    Discharge pump (15 hp)
    Moisture accumulation assembly, carbon canister
    hookup
    Air heater (700 W)
    Vapor-phase carbon canisters (140 Ib)
    Manifold, piping, valves, gauges, sampling ports,
    totalizer, controllers
    Discharge piping and fittings
                          1        each

                          1        each
                          1        each
                      Previously installed
                      Previously installed

                          1        each
                          1        each
                      Previously installed

                          1         lot
                      Previously installed
 3,700      3,700

20,000     20,000
 1,500      1,500
 1,100      1,100
   500        500
15,000     15,000
                                                T-16

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
        January 1997
    Table 10. (Continued)
                                                                            Unit price    Total
                                                       Quantity   Unit type   (1995$)    (1995$)
                                             Eastern GSA
    Ground water extraction and treatment system MEC
    Wellhead vaults, valves, sampling ports, gauges
    Electrical line and conduit
    Electric submersible pumps (1/2 hp)
    2-in. PVC piping
    PVC pipe fittings, unistrut
    Particulate filter assembly
    Low-profile tray air stripper (includes blower and
    transfer pumps, total of 7 hp)
    Moisture accumulation assembly, carbon canister
    hookup
    Vapor-phase carbon canisters (140 Ib)
    Manifold, piping, valves, gauges, sampling ports,
    totalizer, controllers
    Discharge piping and fittings

    Total MEC for eastern GSA ground water treatment
    system

    Total MEC for GSA ground water extraction and SVE
    treatment systems

    Electrical components (20% of MEC)

    Installation cost (58% of MEC)

    Major equipment installed cost (MEIC)

                                          Other capital costs
    Wells/borings
    Ground water extraction well installation and
    development
    Piezometer installation and development
    Soil boring and initial water sample analyses
    Soil disposal (Class III)
    Hydraulic test for ground water extraction wells
    Hydraulic test for reinjection well
    Hydraulic test for piezometers
    Structures
                      3 previously installed
                      Previously installed
                      3 previously installed
                      Previously installed
                      Previously installed
                           1         each

                           1         each

                           1         each
                      Previously installed

                      Previously installed
                      Previously installed
 3,700

20,000

 1,100
 3,700

20,000

 1,100
                                                           24,800
                                                          123,500

                                                           24,700

                                                           71,630

                                                          219,830
4
10
14
35
10
1
10
well
well
well
cuyard
well
well
well
10,000
10,000
1,500
20
3,000
5,000
1,500
40,000
100,000
21,000
700
30,000
5,000
15,000
                                                T-17

-------
UCRL-AR-124061
Final ROD for the CSA Operable Unit. Site 300
         January 1997
    Table 10. (Continued)
Quantity
Equipment building for central GSA SVE treatment
system 1
Equipment building for central GSA ground water
treatment system 1
Equipment building for eastern GSA ground water
treatment system 1
Geotechnical testing 3
Contingency POU ground water treatment system for
off site water-supply wells CDF-1, CO AM, and SR-1
Wellhead modification 3
Particulate filter 3
Aqueous-phase carbon beds (1,000 Ib) 6
Double-containment skid (81 x 15') 3
System plumbing, totalizer, fittings 3
Total field costs (TFC)
Professional environmental services
Design/assist with project management
Permitting
Start-up labor and analyses
SVE performance evaluation
Total professional environmental services
Unit type
each
each
each
each

each
each
each
each
lot





Unit price
(1995 $)
300,000
300,000
300,000
20,000

1,000
2,000
6,000
4,000
2,000





Total
(1995 $)
300,000
300,000
300,000
60,000

3,000
6,000
36,000
12,000
6,000
1,454,530

50,000
50,000
60,000
25,000
185,000
    LLNL tax (11% of total field costs and professional
    environmental services)

    LLNL Environmental Restoration Division (ERD)
    team
    Full-time employee (Fit)
    Remedial Design Report

    Total LLNL ERD team
                                   FTE
180,000
                                                        180,348
540,000
300,000

840,000
                                               T-18

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
    Table 10. (Continued)
Unit price
Quantity Unit type (1995 $)
LLNL technical support services
LLNL Plant Engineering planning and Title I, II, and III
services
Total LLNL support services
Total capital costs


5


Operation and maintenance (O&M)
Fixed O&M costs for soil vapor and ground
Fixed annual O&M costs for SVE
Electricity
Electrical capacity charge
SVE air sampling analysis
Maintenance materials (10% of total installed MEG)
LLNL tax (11% of outside charges)
Project management
System optimization, engineer
Well field optimization, hydrogeologist
Operating labor
Clerical
Maintenance labor (15% of total installation cost)
Total fixed annual SVE O&M costs
Total present worth of fixed O&M for soil vapor
extraction, years 1-10 (factor = 8.317)
Fixed annual ground water extraction and treatment
O&M for central GSA


FTE


costs
water extraction and

30,000
3.7
12


0.15
0.20
0.10
0.30
0.10






Electricity 170,000
Electrical capacity charge
Scale prevention/recarbonation
Ground water treatment system air sampling analysis
Ground water treatment system analyses (water only)
Maintenance materials (10% of total installed MEC)
LLNL tax (11% of outside charges)
Project management
System optimization, engineer
21.6
4,000
12
12


0.10
0.15

kw»h
kw
event


FTE
FTE
FTE
FTE
FTE






kw»h
kw
lbCO2
event
event


FTE
FTE


180,000



treatment

0.07
36
560


238,500
173,500
173,500
129,800
92,600






0.07
36
0.60
560
200


238,500
173,500
Total
(1995$)


900,000
900,000
3,559,878



2,100
133
6,720
8,200
1,887
35,775
34,700
17,350
38,940
9,260
7,134
162,199

1,349,010


11,900
776
2,400
6,720
2,400
16,300
4,455
23,850
26,025
                                               T-19

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
    Table 10. (Continued)

Well field optimization, hydrogeologist
Operating labor
Clerical
Maintenance labor (15% of total installation cost)
Total fixed annual ground water extraction and
treatment O&M for central GSA
Total present worth of annual ground water treatment
O&M for central GSA, years 1-55 (factor = 24.264)
Quantity
0.15
0.30
0.10


Unit type
FTE
FTE
FTE


Unit price
(1995 $)
173,500
129,800
92,600


Total
(1995$)
26,025
38,940
9,260
14,181
183,232
4,445,937
    Fixed annual ground water extraction and treatment
    O&M for eastern GSA
    Electricity
    Electrical capacity charge
    Scale prevention /recarbonation
    Ground water treatment system air sampling analysis
    Ground water treatment system analyses (water only)
    Maintenance materials (10% of total installed MEC)
    LLNL tax (11% of outside charges)
    Project management
    System optimization, engineer
    Well field optimization, hydrogeologist
    Operating labor
    Clerical
    Maintenance labor (15% of total installation cost)
    Total fixed annual ground water extraction and
    treatment O&M for eastern GSA

    Total present worth of annual ground water treatment
    O&M for eastern GSA, years 1-10 (factor = 8.327)
60,000
7.6
12,000
12
12


0.10
0.15
0.15
0.30
0.10

kw»h
kw
lbCO2
event
event


FTE
FTE
FTE
FTE
FTE

0.07
36
0.60
560
200


238,500
173,500
173,500
129,800
92,600

4,200
274
7,200
6,720
2,400
10,000
3,387
23,850
26,025
26,025
38,940
9,260
8,700
                                                         166,981
                                                       1,390,453
    Total present worth of fixed O&M costs for 55 years
                                                       7,185,400
                                               T-20

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
    Table 10.  (Continued)
Unit price Total
Quantity Unit type (1995$) (1995$)
Variable operating costs for soil vapor and
Annual costs, year 1
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 1
Total present worth, year 1 (factor = 0.966)
Annual costs, year 2
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 2
Total present worth, year 2 (factor = 0.934)
Annual costs, year 3
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 3
Total present worth, year 3 (factor = 0.902)
Annual costs, year 4
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 4
Total present worth, year 4 (factor = 0.871)
Annual costs, year 5
SVE replacement of GAC
Ground water treatment system replacement of vapor
GAC
Total annual costs, year 5
Total present worth, year 5 (factor = 0.842)
ground water extraction and treatment

3,950 Ib 2.30 9,085
650 Ib 2.30 1,495
10,580
10,220

980 Ib 2.30 2,254
650 Ib 2.30 1,495
3,749
3,502

490 Ib 2.30 1,127
650 Ib 2.30 1,495
2,622
2,365

125 Ib 2.30 288
650 Ib 2.30 1,495
1,783
1,553

60 Ib 2.30 138
650 Ib 2.30 1,495
1,633
1,375
    Annual costs, years 6-20
                                               T-21

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
    Table 10.  (Continued)

SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 6-10
Total present worth, years 6-10 (factor = 3.801)
Annual costs, years 11-30
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 11-30
Total present worth, years 11-30 (factor = 10.075)
Annual costs, years 31-55
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 31-55
Total present worth, years 31-55 (factor = 5.872)
Total present worth of variable operating costs for
soil vapor and ground water extraction and treatment
Ground water and soil
Annual costs, years 1-10
SVE vapor VOC analysis
VCX: analysis (EPA Method 601)
VCX: analysis (EPA Method 602)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Quarterly monitoring reports
LLNL tax (11% of outside charges)
Monthly SVE vapor sample collection
Quarterly water level measurements (including 10
piezometers)
Quarterly ground water sample collection
Semiannual ground water sample collection
Annual ground water sample collection
Annual spring water sample collection
Maintenance of ground water sampling system
Quantity
5
325


75


5

Unit type
Ib
Ib


Ib


Ib

Unit price
(1995 $)
2.30
2.30


2.30


2.30

Total
(1995 $)
12
748
759
2,885

173
173
1,738

12
12
68
23,705
vapor monitoring

84
206
12
3

4

7
111
7
89
12
3
101

each
each
each
suite

report

well
well
well
well
well
spring
well

110
50
50
545

15,000

375
62.50
500
250
125
125
430

9,240
10,300
600
1,635
2,178
60,000
9,235
2,625
6,938
3,500
22,250
1,500
375
43,430
                                               T-22

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
    Table 10. (Continued)

Project management
Total annual costs, years 1-10
Total present worth, years 1-10 years (factor = 8317)
Annual costs, years 11-55
VOC analysis (EPA Method 8010)
VOC analysis (EPA Method 8020)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Annual monitoring report
LLNL tax (11% of outside charges)
Quarterly water level measurements (including 10
piezometers)
Semiannual ground water sample collection
Annual ground water sample collection
Annual spring water sample collection
Maintenance of ground water sampling system
Project management
Total annual costs, years 11-55
Total present worth, years 11-55 years (factor=15.947)
Annual costs, years 56-60
VOC analysis (EPA Method 601)
VOC analysis (EPA Method 602)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Annual monitoring report
LLNL tax (11% of outside charges)
Quarterly water level measurements (including 10
piezometers)
Semiannual ground water sample collection
Annual ground water sample collection
Quantity
0.35


128
12
3

1

111
39
50
3
91
0.35


111
12
3

1

111
37
37
Unit type
FTE


each
each
suite

report

well
well
well
spring
well
FTE


each
each
suite

report

well
well
well
Unit price
(1995 $)
238,500


50
50
545

15,000

62.50
250
125
125
430
238,500


50
50
545

15,000

62.50
250
125
Total
(1995 $)
83,475
257,280
2,139,796

6,400
600
1,635
864
15,000
2,695
6,938
9,750
6,250
375
39,130
83,475
173,111
2,760,598

5,550
600
1,635
779
15,000
2,592
6,938
9,250
4,625
                                               T-23

-------
tCRL-AR-124061
   Table 10. (Continued)
Final ROD for the GSA Operable Unit. Site 300
January 1997

Annual spring water sample collection
Maintenance of ground water sampling system
Project management
Total annual costs, years 56-60
Total present worth, years 56-60 years (factor = 0.681)
Total present worth of ground water and soil vapor
monitoring for 60 years (5 years after reaching MCLs)
Quantity
3
74
0.15

Unit type
spring
well
FTE

Unit price
(1995 $)
125
430
238^00

Total
(1995$)
375
31,820
35,775
114,938
78,273
4,978,667
                                 Contingency costs and totals
   Subtotal present worth of Alternative 3b



   Contingency (20%)



   Total present worth of Alternative 3b
                                                     15,747,651




                                                      3,149,530




                                                     18,897,181
                                              T-24

-------
Table 11. ARARs for the selected remedy at the GSA OU.
            Action
Ground water extraction
to
            Source
          Description
                                                                                                            Application to the
                                                                                                             selected remedy
Federal:
Safe Drinking Water Act [42
USCA 300 and 40 CFR 141.11-
141.16,141.50-141.51]
(Applicable: Chemical-specific)
                               State:
                               State Water Resources Control
                               Board (SWRCB) Resolution 92-49
                               (Applicable: Chemical-specific)


                               Cal. Safe Drinking Water
                               [California Health and Safety
                               Code Section 116365]
                               (Applicable: Chemical-specific)
                               Chapter 15, Code of California
                               Regulations (CCR), Title 23,
                               Sections 2550.7,2550.10
                               (Applicable: Chemical-specific)
Establishes treatment standards
for current potential drinking
water sources by setting MCLs
and non-zero Maximum
Contaminant Level Goals
(MCLGs), which are used as
cleanup standards. Those
standards for the GSA OU are
listed in Table 9 of the ROD.

Requires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water quality.
Establishes treatment standards
for current potential drinking
water sources by setting MCLs
which are used as cleanup
standards. Those standards for
the GSA OU are listed in Table 9
of the ROD.
Requires monitoring of the
effectiveness of the remedial
actions.
                                                                                              As part of the selected remedy,
                                                                                              VOC concentrations will be
                                                                                              reduced to MCLs in all ground
                                                                                              water in the GSA OU.
                                                               All cleanup activities associated
                                                               with implementation of the
                                                               selected remedy will be
                                                               conducted under the supervision
                                                               of the CVRWQCB.
                                                               As part of the selected remedy,
                                                               concentrations will be reduced to
                                                               MCLs in all ground water in the
                                                               GSA OU.
                                                               During and after completion of
                                                               the selected remedy,
                                                               concentrations of VOCs in in situ
                                                               ground water will be measured.
                                                                                                     c:
                                                                                                     g
                                                                                                                                    I
                                                                                                    §
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                                                                                                                                    u>
                                                                                                                                    jr
                                                                                                                                    8
                                                                                                                                    VI

-------
Table 11. (Continued)
            Action
            Source
          Description
Application to the
 selected remedy

Ground water extraction (cont.)    State: (cont.)
Soil vapor extraction
                                Water Quality Control Plan
                                (Basin Plan) for CVRWQCB

                                (Applicable: Chemical-specific)
SWRCB Resolution 88-63
(Applicable: Chemical-specific)



State:
Water Quality Control Plan
(Basin Plan) for CVRWQCB
(Applicable: Chemical-specific)
                                Chapter 15, CCR, Title 23,
                                Sections 2550.7,2550.10
                                (Applicable: Chemical-specific)
Establishes beneficial uses and
water quality objectives for
ground water and surface waters
in the Central Valley Region as
well as implementation plans to
meet water quality objectives and
protect beneficial uses.

Designates all ground and
surface waters in the State as
drinking water sources with
specific exceptions.
Establishes beneficial uses and
water quality objectives for
ground water and surface waters
in the Central Valley Region, as
well as implementation plans to
meet water quality objectives and
protect beneficial uses.
Requires monitoring of the
effectiveness of the remedial
actions.
                                                                As part of the selected remedy,
                                                                VOC concentrations in ground
                                                                water will be remediated to
                                                                levels listed in Table 9.
                                                                                                As part of the selected remedy,
                                                                                                VOC concentrations will be
                                                                                                reduced to levels protective of
                                                                                                drinking water beneficial use as
                                                                                                described in Section 2.10.1.
                                                                                                As part of the selected remedy,
                                                                                                VOC concentrations in soil vapor
                                                                                                will be remediated to levels
                                                                                                protective of ground water
                                                                                                (MCLs).
                                                                During and after completion of
                                                                the selected remedy,
                                                                concentrations of contaminants
                                                                in in situ soil vapor will be
                                                                measured.
                               i
                                                                       g
                               i.
                                                                                                                                       u>
                                                                                                                                       f

-------
       Table 11. (Continued)
                                                                                                     I
                                                                                                     i.

                   Action
            Source
          Description
       Application to the
        selected remedy
       Contingency POU treatment at
       water-supply wells
State:
Cal. Safe Drinking Water Act
(California Health and Safety
Code Section 116365)
(Applicable: Chemical-specific)
Establishes chemical-specific
standards for public drinking
water systems by setting MCL
goals.
As part of the selected remedy,
VOC concentrations will be
reduced to MCLs by POU
treatment at existing water-
supply wells, if necessary.
       Treated ground water discharge
to
-j
                                       SWRCB Resolution 92-49
                                       (Applicable: Chemical-specific)
State:
SWRCB Resolution 68-16
(Anti-degradation policy)
(Applicable: Chemical-specific)
Requires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water quality.


Requires that high quality
surface and ground water be
maintained to the maximum
extent possible.
All cleanup activities associated
with implementation of the
selected remedy will be
conducted with oversight by the
CVRWQCB.


In the context of the selected
remedy, this is applicable to the
discharges of treated ground
water. The eastern GSA ground
water treatment system (GWTS)
discharges treated water to Corral
Hollow Creek under the
requirements of the current
NPDES permit issued by the
CVRWQCB. The central GSA
GWTS discharges to bedrock in
an onsite canyon under the
requirements of the current
Substantive Requirements issued
by the CVRWQCB.
                                                                                                                                            §
                                                                                                                                           f
                                                                                                                                            I
                                                                                                                                            s-
                                                                                                                                            Ui

-------
Table 11. (Continued)
                                                                                                     I
            Action
            Source
Description
Application to the
 selected remedy
Treated ground water reinjection   Federal:
                                Safe Drinking Water Act
                                Underground Injection Control
                                Program (40 CFR 144.26-124.27)
                                (Applicable:  Action-specific)
                                SWRCB Resolution 68-16 (Anti-
                                degradation policy)
                                (Applicable:  Chemical-specific)
Treated soil vapor discharge
Local:
San Joaquin Valley Unified Air
Pollution Control District
(SJVUAPCD) Rules and
Regulations, Rules 463.5 and 2201
(Applicable: Chemical-specific)
Disposition of hazardous waste    State:
                                Health and Safety Code, Sections
                                25100-25395, CCR, Title 22, Ch.
                                30: Minimum Standards for
                                Management of Hazardous and
                                Extremely Hazardous Wastes
                                (Applicable:  Action-specific)
                               Requires monitoring for
                               reinjection of treated water.
                               Requires that high quality
                               surface and ground water be
                               maintained to the maximum
                               extent possible.
                                                               Regulates nonvehicular sources
                                                               of air contaminants.
                               Controls hazardous wastes from
                               point of generation through
                               accumulation, transportation,
                               treatment, storage, and ultimate
                               disposal.
                      During the selected remedy,
                      treated ground water would be
                      analyzed to verify complete
                      removal of VOCs to regulatory
                      treatment standards, prior to
                      reinjection.
                      During the selected remedy,
                      contaminated soil vapor will be
                      treated with GAC, or equivalent
                      technologies, and discharged to
                      the atmosphere. The compliance
                      standards for treated soil vapor
                      are contained in the current
                      Authority to Construct and
                      subsequent Permit to Operate
                      issued by the SJVUAPCD.


                      For the selected remedy, this
                      ARAR applies primarily to the
                      spent GAC vessels.
                                                                                                                                     50
                                                                                                                                     O
                                                                                                                                     i
                                                                                                                                    f

-------
Table 11. (Continued)
                                                                                                       I
                                                                                                       so
            Action
            Source
Description
Application to the
 selected remedy
Protection of endangered species
Floodplain protection
Federal:
Endangered Species Act of 1973,
16 USC Section 1531 et seq. 50
CFR Part 200, 50 CFR Part 402 [40
CFR 257.3-2J
(Applicable: Location-specific)
State:
California Endangered Species
Act, California Department of
Fish and Game Sections 2050-
2068
(Applicable: Location-specific)
State:
22 CCR 66264.18 (B)(l)
(Applicable: Location-specific)
                                                                Requires that facilities or
                                                                practices not cause or contribute
                                                                to the taking of any endangered
                                                                or threatened species of plants,
                                                                fish, or wildlife.
                                                                NEPA implementation
                                                                requirements may apply.
                      Prior to any well installation,
                      facility construction, or similar
                      potentially disruptive activities,
                      wildlife surveys will be
                      conducted and mitigation
                      measures implemented if
                      required.
                                                                Requires that TSD facilities
                                                                within a 100-year floodplain must
                                                                be designed/ constructed,
                                                                operated, and maintained to
                                                                prevent washout of any
                                                                hazardous waste by a 100-year
                                                                flood.
                      If it becomes necessary to install
                      point-of-use treatment for water-
                      supply wells CDF-1 or CON-1,
                      which are located offsite within
                      the 100-year floodplain, the POU
                      systems would be constructed in
                      accordance with this
                      requirement.	
                                                                                                                                       §
                                §
                               t
                                I
                                                                                                       t/3

                                                                                                       S?

-------
Acronyms and Abbreviations

-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January-1997
                 Acronyms and Abbreviations

AOS         Adult Onsite
ARARs      Applicable or Relevant and Appropriate Requirements
Cal EPA      State of California, Environmental Protection Agency
CARE       Citizens Against a Radioactive Environment
CCR         Code of California Regulations
CDF         California Department of Forestry
CDI         Chronic Daily Intake
CERCLA     Comprehensive Environmental Response, Compensation, and Liability
             Act of 1980
CFR         Code of Federal Regulations
CMB         Claystone Marker Bed
CPF         Cancer Potency Factor
CVRWQCB   Central Valley Regional Water Quality Control Board
DCE         Dichloroethylene
DNAPLs      Dense Nonaqueous Phase Liquids
DOE         Department of Energy
DTSC        California Department of Toxic Substances Control
EPA         U.S. Environmental Protection Agency
ERD         Environmental Restoration Division
FFA         Federal Facility Agreement
FS           Feasibility Study
FTE         Full Time Employee
GAC         Granular Activated Carbon
gal           Gallons
gpm         Gallons per minute
GSA         General Services Area
GWTS       Ground Water Treatment System
HE          High Explosives
HI           Hazard Index
hp           Horsepower
HQ          Hazard Quotient
HMX         Cyclotetramethylenetetranitramine
IRIS         Integrated Risk Information System

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UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
LLNL       Lawrence Livermore National Laboratory
MCLs       Maximum Contaminant Levels
MEC        Major Equipment Cost
MEIC       Major Equipment Installed Cost
mg/kg       Milligrams per kilogram
mg/L        Micrograms per liter
NCP         National Contingency Plan
NEPA       National Environmental Policy Act
NPDES      National Pollutant Discharge Elimination System
O&M        Operation and Maintenance
OSWER      Office of Solid Waste and Emergency Response
OU          Operable Unit
PCE         Tetrachloroethylene
PEFs         Pathway Exposure Factors
POU         Point of Use
ppbv/v        Parts per billion on a volume-to-volume basis.  Also referred to as ppbv
PRGs        Preliminary Remediation Goals
PVC         Polyvinyl Chloride
QA          Quality Assurance
Qal          Quaternary alluvial deposits
QC          Quality Control
Qt           Quaternary terrace deposits
RAOs       Remedial Action Objectives
RES         Residential Exposure
RfD         Reference Dose
ROD         Record of Decision
RWQCB      California Regional Water Quality Control Board
SARA       Superfund Amendments and Reauthorization Act of 1986
SJVUAPCD  San Joaquin Valley Unified Air Pollution Control District
SVE         Soil Vapor Extraction
SWRCB      State Water Resource Control Board
SWRI       Site Wide Remedial Investigation
TCE         Trichloroethylene
TFC         Total Field Cost
Tmss        Miocene Cierbo Formation
Tnbsi        Miocene Neroly Formation - Lower Blue Sandstone Member

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UCRL-AR-124061               Final ROD for the GSA Operable Unit, Site 300           January 1997

Tnb$2        Miocene Neroly Formation - Upper Blue Sandstone Member
Tnsci        Miocene Neroly Formation - Middle Siltstone/Claystone Member
UCRL       University of California Radiation Laboratory
UCL         Upper Confidence Limit
VOCs        Volatile Organic Compounds

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