EPA/ROD/R09-97/043
1997

EPA Superfund

Record of Decision:

LAWRENCE LIVERMORE NATL LAB (SITE 300)
(USDOE)

EPA ID: CA2890090002
OUOl

TRACY, CA
01/29/1997

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EPA/541/R-97/043


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

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

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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

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

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

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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

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 aguifer
(Qt-Tnsc 1) in the central GSA (4th guarter 1995 data).

Figure 7. TCE concentrations in ground water from the Tnbs 1 regional aguifer
in the central GSA (4th guarter 1995 data).

Figure 8. Total VOC concentrations in ground water in the alluvium (Qal) and

shallow bedrock (Tnbs 1) in the eastern GSA (4th guarter 1995 data).

Figure 9. TCE concentrations in ground water from the deeper Tnbs 1 regional
aguifer in the eastern GSA (4th guarter 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 1) in the eastern GSA (4th guarter 1991 data).

Figure 13. TCE concentrations in ground water from the deeper Tnbs 1 regional
aguifer in the eastern GSA (4th guarter 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 aguifer (Qt-
Tnsc 1) in the central GSA (3rd guarter 1992 data).

Figure 16. TCE concentrations in ground water from the Tnbs 1 regional aguifer
in the central GSA (4th guarter 1991 data).

Figure 17. Schematic of the central GSA remediation system for the selected
remedy (Alternative 3b).

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
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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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 IX 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.

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:

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•	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 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:

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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 eguipment 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 guantities 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,
eguipment 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 over-sight 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 reguirements 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 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 lb) 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

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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-1, 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.

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-Tnsc 1 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), Tnbs 2 (Neroly Formation-Upper Blue Sandstone), and Tnsc 1 (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
(Tnsc 1) 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.

•	Tnbs 1 Hydrogeologic Unit (Regional Aquifer): The regional aquifer occurs in the
lower Neroly Formation (Tnbs 1). 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.

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•	Qal-Tmss Hydrogeologic Unit: This hydrogeologic unit is composed of the
stratigraphic units: Qal (alluvium), Tnsc 1, Tnbs 1, and Tmss (Cierbo Formation).
For the most part, the Tnsc 1 aguitard is absent in the eastern GSA, and the shallow
water-bearing zone (Qal) is in hydraulic communication with the underlying regional
aguifer (Tnbs 1). As a result, some contamination has migrated downward from the
shallow-water bearing zone into the regional aguifer. Ground water flow in the
alluvium (Qal) and shallow Tnbs 1 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
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
guantity 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 Ig/L and xylene was detected in well W-7N at a concentration
of 0.96 Ig/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 freguency. The extent and freguency 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 (Ig/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 guarter 1994, the maximum TCE
concentration in ground water samples collected from the Building 875 dry well pad area was
10,000 I/L in well W-71 (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 agueous
solubility of TCE is 1,100,000 Ig/L, TCE concentrations in the range of 11,000 to 110,000 Ig/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 Ig/L) are wells W-875-07, -08, -09,
-10, -11, -15, and W-71. 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).

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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 a depth of 20
to 35 ft near the contact between the Tnbs 2 water-bearing zone and the underlying Tnsc 1
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-Tnsc 1 shallow aguifer 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 Tnbs 1 regional aguifer, the VOC plumes
appear to be confined to the Qt-Tnsc 1 hydrogeologic unit in this area, where the Tnsc 1
confining layer prevents the downward migration of contaminants. West of the sewage treatment
pond, TCE has been detected in ground water in the regional aguifer (Fig. 7) where the Tnsc 1
confining layer is absent. The low TCE concentrations have generally been decreasing in the
regional aguifer 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 aguifer in the vicinity of the debris burial trenches (Fig. 9). TCE in the regional
aguifer in this area is generally limited to portions of the regional aguifer which directly
underlie the contaminated shallow water-bearing zone. The maximum VOC concentrations in ground
water as of fourth guarter 1995 were 20 Ig/L in the shallow water-bearing zone and 19 Ig/L in
the regional aguifer.

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 Tnbs 2 water-bearing zone and the
underlying Tnsc 1 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.

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 technigues, 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.

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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.

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 guantitative
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.

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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 12.0 ft) 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 particulates 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 conseguence 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

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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
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 CDI). 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 turnorigenic
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.

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 o d]) by one or more uncertainty factors (U.S. EPA,
1992a,b,c). Each of these uncertainty factors has a value that ranges from I 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.

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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.	Carcinogenic 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 CDI with a
RfD. When calculated for a single chemical, this comparison yields an HQ. For each chemical
at each location, path way-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.

2.6.6.3.	Additivity of Response

In every location at or near the GSA OU where cancer risk and noncancer HQs were calculated,

CDIs 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).

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.

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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 <
10 -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 -1). While the
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 10 -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 10 -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 5 60. 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

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excess cancer risk and unacceptable noncancer health effects.

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 10 -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 10 -1 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 10 -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.
Conseguently, 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 subseguently 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
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.

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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 aguatic 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
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 subseguent
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 reguirements.

2.7.1. Alternative 1-No Action

A no-action alternative is reguired 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
guality assurance/guality 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

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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.

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
aguifer. 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 aguifers.

Modeling indicates that TCE concentrations in the shallow aguifer in the central GSA dry well

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area need to be reduced to 100 Ig/L to prevent migration of VOCs above MCLs into the regional
aguifer. After the 100 Ig/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 1 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 aguifers.

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 reguired to reduce VOC
concentrations to MCLs in the shallow aguifer 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 aguifer 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 adeguate 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.

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).

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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 Tnbs 1
regional aguifer 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
Tnbs 1 regional aguifer 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
reguirements 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 reguirements of the Safe
Drinking Water Act, the Region V Basin Plan, and State Resolutions 68-16 and 92-49.

•	The goal of Alternative 3a is to use active soil vapor and ground water remediation
to meet the reguirements of the Safe Drinking Water Act, the Region V Basin Plan,
and State Resolutions 68-16 and 92-49 in the Tnbs 1 regional aguifer. This
alternative relies, in part, on natural attenuation and dispersion, and therefore
may not meet these ARARs in the alluvial aguifer in the central GSA.

•	Alternative 3b would use active soil vapor and ground water remediation to meet all
ARARs in both the alluvial and Tnbs 1 regional aguifer.

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.

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•	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 Tnbs 1 regional aguifer. However, this
alternative relies on natural attenuation to reduce VOC concentrations to MCLs in
the alluvial aguifer 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 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 Tnbs 1 regional aguifer 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. Inplementability

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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.

•	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 Tnbs 1 regional aguifer in the central GSA, and 2) the alluvial
aguifer and the Tnbs 1 regional aguifer 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 1 regional aguifers. The cost difference between Alternative 3a
and 3b represents the additional cost of remediating ground water in the Qt-Tnsc 1
aguifer in the central GSA to reduce VOC concentrations to MCLs.

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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.

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 DTSC 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 reguired 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.

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:

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1)	The remaining vadose zone VOC contaminants no longer cause concentrations in the leachate to
exceed the aguifer 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.
Aguifer 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 aguifer 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 reguirements 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 reguired 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.

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 guarterly, 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 freguency 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

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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.

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,

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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
guarterly, and wells W-2513-01 and -02 monitored semiannual. If VOCs are detected in well
W-24P-03, the monitoring freguency of this well will be increased to monthly, and wells W-25D-01
and -02 monitored guarterly. Should VOCs be detected in well W-24P-03, 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 agueous-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 eguivalent 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 ppm v/v in July 1994 to current
concentrations of 5 ppm v/v or below in the second guarter 1996. Similarly, VOC concentrations
in soil vapor samples from the individual SVE wells have decreased from a maximum concentration
of 600 ppm v/v in well W-71 at system startup to a maximum of 33 ppm v/v in well W-875-07 in the
second guarter 1996. As of second guarter 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 adeguately 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 eguivalent soil vapor treatment technologies may be considered, if

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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 guarter 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.

Data collected through fourth guarter 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 alluvial wells between the historical maximum concentration and
the concentration in third guarter 1994. The maximum observed TCE concentration in eastern GSA
alluvial wells in fourth guarter 1995 was 18 Ig/L in well W-26R-01, a significant decrease from
the historical maximum concentration of 74 Ig/L TCE in well W-26R-03 in January 1992.

The 1 Ig/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 Ig/L isoconcentration
contour extended 4,625 ft downgradient based on fourth guarter 1991 (SWRI) data (Fig. 12).

Fourth guarter 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
Ig/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 aguifer 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 Tnbs 1 regional aguifer from a maximum of 71 Ig/L in third
guarter 1992, to a maximum of 19.2 Ig/L in fourth guarter 1995 as shown in Figures 13 and 9,
respectively. In this area, the alluvium and underlying regional aguifer are hydraulically
connected, and contamination in the regional aguifer is a result of downward vertical migration
of contaminants from the alluvial aguifer. An extraction well in the regional aguifer in the
debris burial trench area was not considered due to concerns that pumping the regional aguifer
would accelerate/facilitate downward vertical contaminant migration from the overlying source in
the alluvium into the Tnbs 1. If remediation of the alluvial aguifer does not appear effective

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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:

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 GAC units effectively removed VOCs from ground water to NPDES permit levels (<0.5
Ig/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 Ig/L in September of 1991 to an average of 8.2 Ig/L 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:

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1. Effective in removing VOCs from ground water to NPDES permit levels (<0.5 Ig/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, agueous-phase GAC has replaced air stripping as the preferred technology for the
treatment of ground water in the eastern GSA.

Extracted ground water will continue to be treated by two to three agueous-phase GAC units
connected in series (Fig. 14). Other eguivalent 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 reguirements of 0.5 Ig/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
reguirements 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 reguired by the sewage treatment pond, and the limited time frame when makeup water is
reguired (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 aguifer.

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 1 regional aguifer west of the sewage treatment pond (Fig. 7), the
highest ground water VOC concentrations are in the upgradient overlying alluvial aguifer (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 Tnbs 1
regional aguifer.

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 guarter 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-Tnsc 1 wells during the third guarter 1994 to the historical
maximum observed concentrations indicates an overall decrease in VOC concentrations.
Specifically, the maximum observed TCE concentration for all Qt-Tnsc 1 wells in samples
collected in the third guarter of 1994 was 10,000 Ig/L, representing a decrease from the
historical maximum observed concentration of 240,000 Ig/L in a bailed ground water sample
collected from well W-875-07 in March 1992 (Fig. 15). Third guarter 1994 analytical data suggest
that ground water samples collected from the Building 875 dry well pad wells do not 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 guarter 1994 because these wells have been
effectively dried out preventing ground water sample collection.

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Historically, TCE has been detected in ground water samples from monitor wells located west of
the sewage treatment pond, which are completed in the Tnbs 1 regional aguifer (Fig. 16). Data
indicates that VOC contaminants are in the regional aguifer in the central GSA only where the
regional aguifer directly underlies contaminated portions of the alluvial aguifer, such as the
area immediately west of the sewage treatment pond. "Where present, the Tnsc 1 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-Tnsc 1 aguifer into the underlying Tnbs 1 regional
aguifer.

Data indicate that TCE concentrations have generally been decreasing in all Tnbs 1 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 Tnbs 1 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 Tnbs 1 and, as a result, the TCE concentration in the bedrock aguifer have
decreased.

In addition to the seven existing ground water extraction wells, six existing monitor wells
(W-7F, W-70, 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 Tnbsl regional aguifer.
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 1 regional aguifer west of the sewage treatment pond. However,
extraction from this well may not be initiated until alluvial aguifers extraction stabilizes
capture zones and further reduces contamination in the alluvial aguifer.

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
aguifer 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 Tnbs 1 regional aguifer. 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 reguired 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 aguifer in these
source areas has reached MCLs, as modeling predicts.

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, agueous-phase granular activated carbon (GAC), or other eguivalent 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
Reguirement of 0.5 Ig/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 Reguirements
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 reguired by the sewage treatment
pond, and the limited time frame when makeup water is reguired (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 aguifer.

Once ground water extraction from Tnbs 1 well W-7P is initiated, treated ground water will also

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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 Tnbs 1
regional aguifer. 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 reguirements (<0.5 Ig/L total VOCs). Analyses will also
ensure that concentrations of inorganic compounds do not exceed levels found in water extracted
from the Tnbs 1 regional aguifer.

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 Joaguin
Valley Unified Air Pollution Control District permit reguirements. If agueous-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 subseguent
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.

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
aguifer and Tnbs 1 regional aguifer. 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

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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 adeguately
managed. Should existing dedicated soil vapor monitoring points in the vicinity of Building 875
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 aguifer 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 aguifer 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
aguifer 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 aguifer 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 aguifer 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

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vadose zone and the concurrent soil vapor VOC concentrations, both as a function of time;
and

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 ligted 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 aguifer 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 reguire 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 aguifer cleanup levels. Aguifer 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 aguifer 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 aguifer cleanup level; and

2)	There is relatively little benefit in continuing SVE because aguifer 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.

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, DTSC, and the CVRWQCB on a guarterly 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, eguipment
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 extiaction 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 eguipment may change as the result of modifications

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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 reguirements.

2.10. ARARs

CERCLA Section 121 (d)(2)(A) reguires that remedial actions meet any Federal standards,
reguirements, criteria, or limitations that are determined to be legally applicable or relevant
and appropriate. CERCLA Section 121 (d)(2)(A)(ii) reguires that State ARARs be met if they are
more stringent than Federal reguirements.

There are three general kinds of ARARs:

1.	Chemical-specific reguirements that define acceptable exposure concentrations or water
guality standards,

2.	Location-specific reguirements that may restrict remediation activities at sensitive or
hazard-prone locations such as wildlife habitat and floodplains, and

3.	Action-specific reguirements 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 reguirements 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 reguirements, only the State ARAR is
listed in the table.

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 aguifer
(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 i 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 DTSC, 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 [Ig/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-sguare 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 (gg/L), except for about a 100 ft-sguare 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 ppb (Ig/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

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economics of chlorinating a municipal water supply to remove pathogens and therefore does not
adeguately 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 tip 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.

The CVRWQCB believes that the California Safe Drinking Water and Toxic Enforcement Act of 1986,
Health and Safety Code Section 25249.5 et seg. (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 reguirements (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 guality 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 reguirements. This ROD does not resolve the
ARAR status of State reguirements regarding the establishment of soil cleanup levels.

Chapter 15, CCR Title 23, Sections 2550.7 and 2550.10 are chemical-specific ARARs, which reguire
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 Joaguin 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 reguirements of the NPDES Permit
(Order No. 91-052) for the eastern GSA and the Substantive Reguirements for the central GSA.
These permits are administered by the CVRWQCB. The discharge standards under the current permits
reguire that the monthly median VOC concentration in ground water are reduced to below EPA
Method detection limits for VOCs (<0.5 Ig/L), prior to discharge. Treated vapor will be
discharged according to the reguirements of the "Authority to Construct" or "Permit to Operate"
issued by the SJVUAPCD, which currently reguires that VOC concentrations in vapor be treated to
6 ppm v, prior to discharge to ambient atmosphere.

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:

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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 reguirement.

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 reguirements 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 reguirements 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 reguirements of CCR, Title 22,
Chapter 30 and the Health and Safety Code, Sections 25100-25395.

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.

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2.11. Statutory Determinations

The selected response action for the GSA OU satisfies the mandates of CERCLA Section 12 1. 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 reguirements, 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 Tnbsl
regional aguifer and potential beneficial use of the alluvial aguifer 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.

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 reguirements for CERCLA-NEPA integration. As part of these reguirements, 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

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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.

2.11.6.	I implement ability

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 DTSC 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) non-significant or minor,2)
significant, or 3) fundamental.

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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 guestions
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 Propoted 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, freguency 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 itfind 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.

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
freguency 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 reguired to be conducted at least every five years
to ensure that the selected remedy is effective and continues to adeguately 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

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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 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.

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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 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.

Response to Comment No. 4:

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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 adeguate 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.
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);

iii)	Conduct cleanup in such a way as to minimize time for remediation;

iv)	In the Central GSA, continue efforts to remove contaminant massfrom the ground water and
soil and locate the source of dense non-agueous phase liguid (DNAPL).

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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 Ig/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-sguare 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-sguare 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 (Ig/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 reguired 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 eguivalent 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-7L 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.

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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 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 guarters (or years) that monitoring will be reguired 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 975 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 agueous solubility of TCE is 1,100,000
Ig/L, TCE concentrations in the range of 11,000 to 110,000 Ig/L or greater would indicate DNAPL.
The cleanup goals established for ground water (i.e., 5 Ig/L for TCE) are well below the
concentrations indicative of DNAPLs (11,000 Ig/L 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-agueous phase liguids with the concentrations of TCE that you have at 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 FY 1998 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

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below the line. So, there is not even any consideration that DOE is going to even ask for money
that will adeguately 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 reguirement 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 on going problems that will threaten the entire cleanup because there is
not the money to go out and do the source investigation needed to fimd 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.

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 of TCE 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 of TCE. 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 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.

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 -6). CERCLA guidelines require cleanup
to 1 x 10 -4 to 1 x 10 -6 ILCR. The Preliminary Remediation Goal (PRG) for TCE is the most
current attempt to define the 1 X 10 -6 cleanup standard. The PRG for TCE is 1.8 ppb. We believe
that PRGs should be adoptedfor 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 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 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 [Ig/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 (Ig/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."

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 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 needfor 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 adeguate and so I
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 adeguately funded and progressive cleanup effort
through its annual Congressional budget reguest each year. DOE does commit to reguest 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.

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References

Anspaugh, L. R., J. H. Shinn, P. L. Phelps and N. C. Kennedy (1975), "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

Polychlorinated 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-2 6.

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.11: 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.
Regist. 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).

U.S.EPA (1991), Risk Assessment Guidance for Superfund, Vol.1: 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]).

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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-1992 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 Nonagueous Phase Liguids-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 IX, to L. Tan, Remedial Project Manager, U.S. Environmental Protection Agency
Region IX, regarding a "Technical reguest 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 Nonagueous Phase

Liguids 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.

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Figures

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Tables

Table 1. Contaminants of potential concern in ground water in the GSA.

Contaminant
Central GSA

Maximum
concentration a

Mean

concentration a,b

95% UCL a

1,1,1-trichloroethane

2.

.0

X

10

3

2.

.93

X

10

-1

1.

.62

X

10

0

1,1-dichloroethylene

4.

.0

X

10

3

7.

.37

X

10

-1

1.

.18

X

10

0

cis-1,2-dichloroethylene c

1.

.0

X

10

3

2.

.56

X

10

0

3.

.75

X

10

0

Acetone

8.

.2

X

10

0

4.

.08

X

10

0

5.

.78

X

10

0

Benzene

5.

.0

X

10

Id





















Bromodichloromethane

3.

.3

X

10

0

4.

.05

X

10

-2

6.

.62

X

10

-2

Chloroform

7.

.4

X

10

0

6.

.10

X

10

-1

8.

.98

X

10

-1

Tetrachloroethylene

2.

.5

X

10

4

3.

.89

X

10

1

7.

.73

X

10

1

Trichloroethylene

2.

.4

X

10

5

8.

.30

X

10

2

3.

.09

X

10

3

Trichlorofluoromethane (Freon 113)

1.

. 6

X

10

2

1.

.07

X

10

1

1.

.89

X

10

1

Eastern GSA

1,1,1-trichloroethane

9.4

X

10

1

2.93

X

10

-1

1.62

X

10

0

1,1-dichloroethylene

5.0

X

10

-1

4.30

X

10

-1

4.45

X

10

-1

1,2-dichloroethylene c

6.0

X

10

-1

4.27

X

10

-1

4.41

X

10

-1

Bromodichloromethane

3.3

X

10

0

4.05

X

10

-2

6.62

X

10

-2

Chloroform

1.4

X

10

1

9. 60

X

10

-1

4.25

X

10

0

Tetrachloroethylene

4.4

X

10

0

1.32

X

10

0

1.64

X

10

0

Trichloroethylene

6.1

X

10

1

2.66

X

10

1

3.39

X

10

1

a All units are in Ig/L.

b 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-1,2-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.

d 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 guarter of
sampling data included in the SWRI database (first guarter, 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.

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Table 2. Contaminants of potential concern in surface soil ( 0.5 ft) in the GSA.

Maximum	Mean

Contaminant	concentration a	concentration a,b	95% UCL a

1,1,1-trichloroethane

5.0

X

10

-3

6.85 x

10

-4

1.86 x 10

-3

Acetone

6.0

X

10

-2

3.39 x

10

-2

4.90 x 10

-2

Cadmium

1.6

X

10

1

6.43 x

10

0

9.31 x 10

0

Chloroform

3.0

X

10

-4

3.82 x

10

-4

8.75 x 10

-4

Copper

3.4

X

10

2

3.94 x

10

1

5.67 x 10

1

HMX

2.0

X

10

-2

NA

c



2.0 x 10 -

-2c

Tetrachloroethylene

3.0

X

10

-2

1.61 x

10

-3

3.58 x 10

-3

Toluene

6.0

X

10

-3

1.30 x

10

-3

2.86 x 10

-3

Trichloroethylene

8.4

X

10

-2

3.75 x

10

-3

1.18 x 10

-2

Trichlorofluoromethane (Freon 113)

1.3

X

10

-2

1.00 x

10

-3

2.19 x 10

-3

Trichlorotrifluoroethane (Freon 11)

7.9

X

10

-2

1.23 x

10

-2

3.84 x 10

-2

Xylenes (total isomers)

7.0

X

10

-3

1.47 x

10

-3

3.40 x 10

-3

Zinc

8.3

X

10

2

2.06 x

10

2

3.62 x 10

2

a Units are mg/kg.

b Estimate of the arithmetic mean of the underlying log normal distribution.

c For certain data sets, calculation of an UCL yielded a value greater than the maximum
measured concentration. In those instances, a mean concentration was not calculated, and
the maximum concentration is given instead of a UCL.

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Table 3. Contaminants of potential concern in subsurface soil (>0.5-12.0 ft) in the GSA.

Operable unit
region

Contaminant

Maximum
concentration a

Mean

concentration a,b	95% UCL a

Building 875 1,1,1-trichloroethane
1,1-dichloroethylene
cis-1,2-dichloroethylene
Chloroform
Tetrachloroethylene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 11)

Debris burial Chloroform
trenches	Methylene chloride

Tetrachloroethylene
Toluene

Trichloroethylene
Trichlorofluoromethane
(Freon 113)

Trichlorotrifluoroethane

1.0 x 10 -2
5.0 x 10 -4
3.0 x 10 -4
3.0 x 10 -4
1.0 x 10 -1

5.4	x 10 -1
6.0 x 10 -2

4.3	x 10 -2

1.4	x 10 -2
8.8	x 10 -3
5.0 x 10 -3
2.4	x 10 -2
3.3 x 10 -3

4.0 x 10 -4

2.13	x 10	-3

NC c

1.88	x 10	-4

1.88	x 10	-4

3.28	x 10	-2

1.74	x 10	-1

8.03	x 10	-3

1.47	x 10	-3

4.26	x 10	-4

1.95	x 10	-3

2.73	x 10	-3

2.43	x 10	-3

1.34	x 10	-4

1.20	x 10	-4

4.38 x 10 -3
5.0 x 10 -4c
2.96 x 10 -4
2.96 x 10 -4
7.54 x 101 -2
4.14 x 10 -1
1.87 x 10 -2

3.35 x 10 -3
1.74 x 10 -3
4.32 x 10 -3
3.14 x 10 -3
4.31 x 10 -3
3.95 x 10 -4

1.67 x 10 -4

(Freon 11)
a Units are mg/kg.

b 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.

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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-trichloroethane
1,2,4-trichlorobenzene
Dichlorodifluoromethane

(Freon 12)

Methylene chloride

Styrene

Toluene

Trichloroethylene
Trichlorotrifluoroethane

(Freon 113)

m- and p-xylenes
o-xylenes

Limit
of detection
(mg/m 2os)

Maximum
emission rate
(mg/m 2os)

Mean
emission rate a
(mg/m 2os)

95% UCL of
emission rate
(mg/m 2os)

1.05

X

10

-6

9.19

X

10

-6

1.25 x

10

-6

2.00

X

10

-6

1.10

X

10

-6

2.00

X

10

-6

NA

b



2.10

X

10

-6

6.79

X

10

-7

2.39

X

10

-5

1.73 x

10

-6

3. 64

X

10

-6

9.50

X

10

-7

5.20

X

10

-5

4.36 x

10

-6

1. 69

X

10

-5

8.01

X

10

-7

3.59

X

10

-6

1.03 x

10

-6

1.37

X

10

-6

1.13

X

10

-6

3.73

X

10

-6

3.33 x

10

-7

1.11

X

10

-6

1.70

X

10

-6

3.88

X

10

-4

7.49 x

10

-5

2.22

X

10

-4

9.58 x 10 -7
9.58 x 10 -7

5.27 x 10 -6
2.43 x 10 -6

1.11 x 10 -6
5.15 x 10 -7

1.97 x 10 -6
9.35 x 10 -7

CO

X

10

-6

1.09

X

10

-6

1.09

X

10

-6

1.32

X

10

-6

2.11

X

10

-6

2.45

X

10

-6

1.11

X

10

-6

1.11

X

10

-6

6.48

X

10

-7

1.32 x 10 -3
1.36 x 10 -6
1.12 x 10 -6

8.67

X

10

-7

6.06

X

10

-5

7. 63

X

10

-6

3.52

X

10

-5

9.07

X

10

-7

1.42

X

10

-6

4.90

X

10

-7

1.01

X

10

-6

8.34

X

10

-7

1. 67

X

10

-6

1.10

X

10

-6

1.27

X

10

-6

1.18

X

10

-6

1.77

X

10

-6

6.89

X

10

-7

1.35

X

10

-6

1.77

X

10

-5

5. 67

X

10

-5

3.40

X

10

-5

4.06

X

10

-5

9.98 x 10 -7
9.98 x 10 -7

2.87 x 10 -6
1.45 x 10 -6

1.32 x 10 -6
6.13 x 10 -7

1.63 x 10 -6
1.16 x 10 -6

-------
Building 875 dry well area

1,2,4-trimethylbenzene

1.09

X

10

-6

3.89

X

10

-6

1.09 x

O
1

Ch

1.98

X

10

-6

Chloromethane

4.63

X

10

-7

1.12

X

10

-6

1.87 x

10 -7

4.38

X

10

-7

Dichlorodifluoromethane

1.09

X

10

-6

1.10

X

10

-6

NA

b

1.10

X

10

-6

(Freon 12)

Ethylbenzene

9.98

X

10

-7

4.49

X

10

-6

8.77 x 10 -7

1.41

M
O

1

Ch

Methylene chloride

7.71

X

10

-7

2.02

X

10

-5

6.37 x 10 -6

1.14

x 10 -5

Tetrachloroethylene

1.54

X

10

-6

2.20

X

10

-6

1.02 x 10 -6

1.83

x 10 -6

Toluene

8.34

X

10

-7

1.05

X

10

-5

1.55 x 10 -6

2.97

x 10 -6

Trichloroethylene

1.18

X

10

-6

1. 68

X

10

-5

3.01 x 10 -6

1.13

x 10 -5

Trichlorotrifluoroethane

1.82

X

10

-6

8.06

X

10

-5

2.86 x 10 -5

3.96 x

10 -5

(Freon 113)

m- and p-xylenes	9.98 x 10 -7	1.83 x 10 -5	2.98 x 10 -6	1.30 x 10 -5

o-xylenes	9.98 x 10 -7 3.37 x 10 -6 7.03 x 10 -7	1.39 x 10 -6

a Estimate of the arithmetic mean of the underlying log normal distribution.

b For certain data sets, calculation of an UCL yielded a value greater than the maximum measured concentration.
In those instances, a mean concentration was not calculated, and the maximum concentration is given instead
of a UCL.

-------
Table 6. (Continued)

Potential
exposure pathway

Additive incremental

excess lifetime
cancer risk estimate

Additive
hazard index

Location of related tables in
supporting documents

Adult Onsite Exposure in the GSA

9 x 10 -7

9.8 x 10 -3

FS:

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

Table 1-37
SWRI (Chapter 6):

Table 6-55
FS:

Table 1-26

a)

7

X

10

-2

a)

5.6

X

10

2

SWRI (Appendix P)

b)

5

X

10

-5

b)

5.0

X

10

-1

Tables P-27-6.5

c)

1

X

10

-5

c)

1.4

X

10

-1

P-27-6.6

d)

2

X

10

-5

d)

1.6

X

10

-1

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.

-------
Table 6. Cancer risk and hazard index summary, and reference list for the GSA OU.

Potential
exposure pathway

Additive incremental

excess lifetime
cancer risk estimate

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)

2 x 10 -7

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

7 x 10 -7

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

2 x 10 -7

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

1 x 10 -5

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

a)	2 x 10 -7

b)	2 x 10 -10

Additive
hazard index

References for related tables
in supporting documents

6.2 x 10 -3

1.2 x 10 -3

1.3 x 10 -3

3.0 x 10 -1

a)	5.6 x 10 -5

b)	8.5 x 10 -3

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

-------
Table 7. Summary of GSA OU remedial alternatives.

Alternative 1: No action

o 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.

o Administrative controls

-	Fencing and warning signs around site.

-	Full-time security guards on site,
o 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.

Alternative 2: Exposure
control

All elements of Alternative 1 plus:
o 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.

Alternative 3a: Remediation
and protection of the Tnbs 1
regional aguifer

All 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,
o Ground water extraction and treatment

Extract ground water from 20 extraction wells (19 shallow
alluvial, 1 Tnbs 1 regional) and reinject into 1 well (Tnbs 1
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 4 6+ gpm at the eastern GSA.

Extract ground water from Tnbs 1 regional aguifer until VOC
concentrations reach MCLs.

Extract ground water from the alluvial aguifer until ground
water VOC concentrations are reduced to levels protective of
the Tnbs 1 regional aguifer (approximately 100 Ig/L).

-------
Table 7.

(Continued)

o 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.

o 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 All elements of Alternative 3a plus:

water plume remediation o 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.

-------
Table 8. Comparative evaluation of remedial alternatives for the GSA OU.

Overall protection

Alternative

of human health and
environment

Compliance
with ARARs

Short-term
effectiveness

Alternative 1 Human health:
No action	No

Environment: No

Criterion may
be met c

Protective of site workers
and the community during
monitoring by preventing
potential exposure through
the use of administrative
controls and/or use of
protective eguipment.

Ground water and air risks
not addressed.

Alternative

Exposure

control

Human health:
Air No
Ground water:
Yes d
Environment: No

Criterion may
be met c

Protective of site workers
and the community during
exposure through the use of
administrative controls
and/or use of protective
eguipment.

Addresses ground water
risk with POU treatment at
existing water-supply
wells. Does not address air
risk.

Alternative 3a

Remediation

and

protection of
the regional
aguifer

Human health:
Air: Yes

Ground water: Yes
Environment: Yes

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
eguipment.

Addresses site risks with
active remediation of soil
and ground water.

Long-term
effectiveness and
permanence

Not effective.

Reduction in
contaminant volume,
toxicity, and mobility

Dependent on
natural attenuation
and degradation.

Implementability
Implementable

Cost a,b
3 .47

Effective for ground
water risks at existing
term reduction of VOC
mass or air risk

Dependent on
natural attenuation
and degradation.

Implementable

Effective for air and
ground water risk in
the Tnbs 1 aguifer.
May not be effective for
ground water risk in
shallow aguifer in the
central GSA.

Ground water and soil
vapor extraction
increases source
removal effectiveness.

Reduction in shallow
unsaturated zone,
and shallow and deep
aguifer

contamination;
partially dependent
on natural
attenuation and
degradation.

Implementable

-------
Table 8. (Continued)

Alternative

Overall protection
of human health and
environment

Compliance
with ARARs

Short-term
e f fectivenes s

Long-term
effectiveness and

permanence

Reduction in
contaminant volume,

toxicity, and mobility Implementability Cost a,b

Alternative
3b

Ground water
and soil
remediation
of both
shallow and
regional
aguifers

Human health:
Air Yes
Ground water: Yes

Environment: Yes

Criterion 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
eguipment.

Addresses site risks with
active remediation of soil
and ground water.

Effective for air and
ground water risks.
Ground water and soil
vapor extraction
address all soil and
ground water
contamination.

Reduction in shallow Implementable

unsaturated zone,

and shallow and deep

aguifer

contamination.

18.90

a Estimated total present worth in millions of 1995 dollars. Overall cost is highly dependent on the reguired length of pumping time.

b 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 reguirements.
c Relies solely on natural attenuation and degradation to comply with Safe Drinking Water Act, Basin Plan, and State Resolutions 68-16 and 92-49.
d Protective of human health for ingestion of ground water from existing water-supply wells.

-------
Table 9. Chemical-specific ARAB.S for potential chemicals of concern in ground water at the
GSA OU.

Chemical of concern

Cancer
group a

Federal MCL
(Ig/L)

State
MCL (Ig/L)

1,1,1-trichloroethane	D

1,1-dichloroethylene	C

cis-1,2-dichloroethylene	D

Benzene	A

Bromodichloromethane	B2

Chloroform	B2

Tetrachloroethylene	B2-C

Trichloroethylene	B2-C

200
7
70
5

100 b
100 b
5
5

200
6
6
1

100b
100b
5
5

a Integrated Risk Information System (IRIS) database maintained by the U.S. EPA.
U.S. EPA cancer group:

A = Known carcinogen.

B2 = Probable carcinogen.

C = Possible carcinogen.

D = Noncarcinogen.
b Total trihalomethanes.

NA = Not available.

Ig/L = Micrograms per liter.

-------
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	7 previously installed

Additional wellhead vaults, valves, sampling ports,

gauges	10	each	1,500	15,000

Electrical line and conduit	1,200	foot	1.75	2,100

2-in. polyvinyl chloride (PVC) piping	1,200	foot	1.50	1,800

Electric submersible pumps (1 /2 horse power [hp]) 10 previously	installed

Additional electric submersible pumps (1/2 hp)	10	each	800	8,000

PVC pipe fittings, unistrut	1	lot 10,000	10,000

SVE blower system (5 hp)	1	each	2,000	2,000

SVE pitot tubes, vacuum gauges, sampling ports	Previously installed

SVE treatment MEC

Moisture accumulation assembly, carbon canister

hookup	Previously installed

Vapor-phase carbon canisters (1,000 lb)	3	each 6,000	18,000

SVE manifold, piping	Previously installed

-------
Table 10. (Continued)

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 lb)

each 3,700

each 20,000
each 1,500

Previously installed
Previously installed

each
each

1,100
500

Previously installed

Manifold, piping, valves, gauges, sampling ports,
totalizer, controllers

Discharge piping and fittings

1	lot

Previously installed
Eastern GSA

15,000

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)

3 previously installed
Previously installed
3 previously installed
Previously installed
Previously installed
1	each

1	each

3,700

20,000
1,500

1,100
500

15,000

3,700

20,000

3,700

20,000

-------
Table 10. (Continued)

Moisture accumulation assembly, carbon canister
hookup

Vapor-phase carbon canisters (140 lb)

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 eguipment installed cost (MEIC)

1	each

Previously installed

Previously installed
Previously installed

1,100

1,100

Other capital costs

WeiIs/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

4
10
14
35
10
1

10

well
well
well
cu yard
well
well
well

10,000
10,000
1,500
20
3, 000
5, 000
1,500

24,800

123,500
24,700
71,630
219,830

40,000
100,000
21,000
700
30,000
5, 000
15,000

-------
Table 10. (Continued)

Structures

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
offsite water-supply wells CDF-1, CON-1, and SR-1

Wellhead modification	3

Particulate filter	3

Aqueous-phase carbon beds (1,000 lb)	6

Double-containment skid (8'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

LLNL tax (11% of total field costs and professional
environmental services)

each	300,000	300,000

each	300,000	300,000

each	300,000	300,000

each	20,000	60,000

each	1,000	3,000

each	2,000	6,000

each	6,000	36,000

each	4,000	12,000

lot	2,000	6,000

1,454,530

50,000
50,000
60,000
25,000
185,000

180,348

-------
Table 10. (Continued)

LLNL Environmental Restoration Division (ERD)
team

Full-time employee (FTE)	3	FTE

Remedial Design Report

Total LLNL ERD team

LLNL technical support services

LLNL Plant Engineering planning and Title I, II, and III

services	5	FTE

Total LLNL support services
Total capital costs

Operation and maintenance (O&M) costs
Fixed O&M costs for soil vapor and ground water extraction and treatment

Fixed annual O&M costs for SVE
Electricity

Electrical capacity charge
SVE air sampling analysis

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)

30,000
3.7
12

kwDh

kw
event

0.15
0.20
0.10
0.30
0.10

FTE
FTE
FTE
FTE
FTE

180,000 540,000
300,000
840,000

180,000

0.07
36
560

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

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

-------
Table 10. (Continued))

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

Electricity	170,000

Electrical capacity charge	21.6

Scale prevention/recarbonation	4,000

Ground water treatment system air sampling analysis	12

Ground water treatment system analyses (water only)	12
Maintenance materials (10% of total installed MEC)

LLNL tax (11% of outside charges)

Project management	0.10

System optimization, engineer	0.15

Well field optimization, hydrogeologist	0.15

Operating labor	0.30

Clerical	0.10

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)

162,199

1,349,010

kwDh	0.07	11,900

kw	36	776

lb C02	0.60	2,400

event	560	6,720

event	200	2,400

16,300
4, 455

FTE	238,500	23,850

FTE	173,500	26,025

FTE	173,500	26,025

FTE	129,800	38,940

FTE	92,600	9,260

14,181

183,232
4,445,937

-------
Table 10. (Continued)

Fixed annual ground water extraction and treatment
O&M for eastern GSA

Electricity	60,000

Electrical capacity charge	7.6

Scale prevention/recarbonation	12,000

Ground water treatment system air sampling analysis	12

Ground water treatment system analyses (water only)	12
Maintenance materials (10% of total installed MEC)

LLNL tax (11% of outside charges)

Project management	0.10

System optimization, engineer	0.15

Well field optimization, hydrogeologist	0.15

Operating labor	0.30

Clerical	0.10

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)

Total present worth of fixed O&M costs for 55 years

kwDh	0.07	4,200

kw	36	274

lb C02	0.60	7,200

event	560	6,720

event	200	2,400

10,000
3,387

FTE	238,500	23,850

FTE	173,500	26,025

FTE	173,500	26,025

FTE	129,800	38,940

FTE	92,600	9,260

8,700

166,981

1,390,453
7,185,400

-------
Table 10. (Continued)

Variable operating costs for soil vapor and ground water extraction
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	60	lb

Ground water treatment system replacement of vapor

GAC	650	lb

Total annual costs, year 5

Total present worth, year 5 (factor = 0.842)

3,950	lb

650	lb

980
650

lb
lb

490
650

lb
lb

125

650

lb

lb

and treatment

2.30	9,085

2.30	1,495

10,580
10,220

2.30	2,254

2.30	1,495

3,749
3,502

2.30
2.30

1,127

1,495
2, 622
2,365

2.30	288

2.30	1,495

1,783
1,553

2.30	138

2.30	1,495

1, 633
1,375

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Table 10. (Continued)

Annual costs, years 6-10

SVE replacement of GAC	5

Ground water treatment system replacement of vapor
phase GAC	325

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	75

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	5

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 vapor monitoring

Annual costs, years 1-10

SVE vapor VOC analysis	84

VOC analysis (EPA Method 601)	206

VOC analysis (EPA Method 602)	12

Annual spring water sample analyses	3
QA/QC analyses (10% of analytic costs)

Quarterly monitoring reports	4
LLNL tax (11% of outside charges)

Monthly SVE vapor sample collection	7
Quarterly water level measurements (including 10

piezometers)	111

Quarterly ground water sample collection	7

Semiannual ground water sample collection	89

Annual ground water sample collection	12

Annual spring water sample collection	3

Maintenance of ground water sampling system	101

Proj ect management	0.35

lb
lb
2,885

lb

lb

each
each
each
suite

report

well

well

well

well

well

spring

well

FTE

2.30	12

2.30	748

759

2.30	173

173
1,738

2.30	12

12
68

23,705

110
50
50
545

15,000

375

9,240
10,300
600

1,	635
2,178

60,000
9,235

2,	625

62.50
500
250
125
125
430
238,500

6, 938
3,500
2,250
1,500
375
43,430
83,475

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Total annual costs, years 1-10

Total present worth, years 1-10 years (factor = 8.317)

Annual costs, years 11-55

VOC analysis (EPA Method 8010)	128

VOC analysis (EPA Method 8020)	12

Annual spring water sample analyses	3

QA/QC analyses (10% of analytic costs)

Annual monitoring report	1

LLNL tax (11% of outside charges)

Quarterly water level measurements (including 10

piezometers)	111

Semiannual ground water sample collection	39

Annual ground water sample collection	50

Annual spring water sample collection	3

Maintenance of ground water sampling system	91

Proj ect management	0.35

Total annual costs, years 11-55
Total present worth, years (factor=15.947)

Annual costs, years 5 6-60

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
Annual spring water sample collection
Maintenance of ground water sampling system
Proj ect management
Total annual costs, years 5 6-60

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)

Contingency costs and totals

Subtotal present worth of Alternative 3b
Contingency (20%)

Total present worth of Alternative 3b

18,

111

12

3

1

111
37
37
3

74
0.15

257,280
2,139,796

each
each
suite

report

well
well
well
spring
well
FTE

each
each
suite

report

well
well
well
spring
well
FTE

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
375
31,820
35,775
114,938
78,273

4,978,667

15,747,651
3,149,530

50

50

545

15,000

62.50

250

125

125

430

238,500

50

50

545

15,000

62.50

250

125

125

430

238,500

, 181

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Table 11. ARARs for the selected remedy at the GSA OU.

Action

Source

Ground water extraction

Federal:

Safe Drinking Water [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)

Description

Application to the
selected remedy

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.

As part of the selected remedy,
VOC concentrations will be
reduced to MCLs in all ground
water in the GSA OU.

Reguires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water guality.

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.

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.

Reguires monitoring of the
effectiveness of the remedial
actions.

During and after completion of
the selected remedy,
concentrations of VOCs in in situ
ground water will be measured.

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Table 11. (Continued)

Action

Ground water extraction (cont.)

Source

State: (cont.)

Water Quality Control Plan
(Basin Plan) for CVRWQCB

(Applicable: Chemical-specific)

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

Soil vapor extraction	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)

Description

Application to the
selected remedy

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.

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.

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 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 vapor will be
measured.

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Table 11. (Continued)

Action

Contingency POU treatment at
water-supply wells

Source

State:

Cal. Safe Drinking Water Act
(California Health and Safety
Code Section 116365)

(Applicable: Chemical-specific)

SWRCB Resolution 92-49

(Applicable: Chemical-specific)

Treated ground water discharge

State:

SWRCB Resolution 68-16
(Anti-degradation policy)
(Applicable: Chemical-specific)

Description

Application to the
selected remedy

Establishes chemical-specific
standards for public drinking
water systems by setting MCL
goals.

Reguires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water guality.

As part of the selected remedy,
VOC concentrations will be
reduced to MCLs by POU
treatment at existing water-
supply wells, if necessary.

All cleanup activities associated
with implementation of the
selected remedy will be
conducted with oversight by the
CVRWQCB.

Reguires that high guality
surface and ground water be
maintained to the maximum
extent possible.

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
reguirements of the current
NPDES permit issued by the
CVRWQCB. The central GSA
GWTS discharges to bedrock in
an onsite canyon under the
reguirements of the current
Substantive Reguirements issued
by the CVRWQCB.

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Table 11. (Continued)

Action

Treated ground water reinjection

Source

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 Joaguin Valley Unified Air
Pollution Control District
(SJVUAPCD) Rules and
Regulations, Rules 4 63.5 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)

Application to the
Description	selected remedy

Reguires monitoring for
reinjection of treated water.

Reguires that high guality
surface and ground water be
maintained to the maximum
extent possible.

During the selected remedy,
treated ground water would be
analyzed to verify complete
removal of VOCs to regulatory
treatment standards, prior to
reinj ection.

Regulates nonvehicular sources
of air contaminants.

During the selected remedy,
contaminated soil vapor will be
treated with GAC, or eguivalent
technologies, and discharged to
the atmosphere. The compliance
standards for treated soil vapor
are contained in the current
Authority to Construct and
subseguent Permit to Operate
issued by the SJVUAPCD.

Controls hazardous wastes from
point of generation through
accumulation, transportation,
treatment, storage, and ultimate
disposal.

For the selected remedy, this
ARAR applies primarily to the
spent GAC vessels.

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Table 11. (Continued)

Action	Source

Protection of endangered species	Federal:

Endangered Species Act of 1973,
16 USC Section 1531 et seg. 50
CFR Part 200, 50 CFR Part 402 [40
CFR 257.3-2]

(Applicable: Location-specific)
State:

California Endangered Species
Act, California Department of
Fish and Game Sections 2050-
2068

(Applicable: Location-specific)
Floodplain protection	State:

22 CCR 66264.18 (B)(1)
(Applicable: Location-specific)

Description

Application to the
selected remedy

Reguires that facilities or
practices not cause or contribute
to the taking of any endangered
or threatened species of plants,
fish, or wildlife.

NEPA implementation
reguirements may apply.

Prior to any well installation,
facility construction, or similar
potentially disruptive activities,
wildlife surveys will be
conducted and mitigation
measures implemented if
reguired.

Reguires 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
reguirement.

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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

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

ppb v/v	Parts per billion on a volume-to-volume basis. Also referred to as ppb v.

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 198 6

SJVUAPCD	San Joaquin Valley Unified Air Pollution Control District

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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

Tnbs

1

Miocene Neroly Formation - Lower Blue Sandstone Member

Tnbs

2

Miocene Neroly Formation - Upper Blue Sandstone Member

Tnsc

1

Miocene Neroly Formation - Middle Siltstone/Claystone Member

UCRL



University of California Radiation Laboratory

UCL



Upper Confidence Limit

VOCs



Volatile Organic Compounds

-------