PB97-964505
EPA/541/R-97/043
November 1997
EPA Superfund
Record of Decision:
Lawrence Livermore Laboratory
(USDOE) Operable Unit 1,
Livermore, CA
1/29/1997
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UCRL-AR-124061
Final Record of Decision for the
General Services Area Operable Unit
Lawrence Livermore National
Laboratory Site 300
January 1997
Environmental Protection Department
Environmental Restoration Program and Division
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Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore
National Laboratory under Contract \V-7405-Eng-48.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Table of Contents
1. Declaration 1-1
1.1. Site Name and Location 1-1
1.2. Statement of Basis and Purpose 1-1
1.3. Assessment of the Site 1-1
1.4. Description of the Selected Remedy 1-1
1.5. Statutory Determinations .% 1-2
1.6. Acceptance of the Record of Decision by Signatory Parties 1-3
2. Decision Summary 2-1
2.1. Site Name, Location, and Description 2-1
2.2. Site History and Summary of Enforcement 2-1
2.3. Highlights of Community Participation 2-2
2.4. Scope and Role of the GSA OU 2-2
2.5. Site Characteristics 2-3
2.5.1. Chemical Releases 2-3
2.5.2. VOCs in Ground Water 2-4
2.5.3. VOCs in Soil/Rock 2-5
2.5.4. VOCs in Soil Vapor 2-6
2.6. Risk Assessment 2-6
2.6.1. Identification of Chemicals of Potential Concern 2-7
2.6.2. Identification of Contaminated Environmental Media 2-7
2.6.3. Estimates of Potential Exposure-Point Concentrations 2-7
2.6.4. Human Exposure and Dose Assessments 2-8
2.6.5. Toxicity Assessment 2-9
2.6.6. Risk Characterization , 2-10
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
2.6.7. Summary of Human Health Baseline Risks and Hazards
Associated with Contaminants 2-11
2.6.8. Summary of the Baseline Ecological Assessment 2-14
2.7. Description of Remedial Action Alternatives 2-14
2.7.1. Alternative 1—No Action 2-15
2.7.2. Alternative 2—Exposure Control 2-15
2.7.3. Alternative 3—Source Mass Removal and Ground Water Plume
Control 2-16
2.8. Summary of Comparative Analysis of Alternatives 2-17
2.8.1. Overall Protection of Human Health and the Environment 2-18
2.8.2. Compliance with ARARs 2-18
2.8.3. Short-Term Effectiveness 2-19
2.8.4. Long-Term Effectiveness and Permanence 2-19
2.8.5. Reduction of Contaminant Toxicity, Mobility, or Volume 2-20
2.8.6. Implementability 2-20
2.8.7. Cost Effectiveness 2-20
2.8.8. State Acceptance 2-21
2.8.9. Community Acceptance 2-22
2.9. Selected Remedy 2-22
2.9.1. Cleanup Goals 2-22
2.9.2. Treatment System Design 2-23
2.9.3. Performance Evaluations 2-32
2.9.4. Innovative Technologies 2-35
2.9.5. Reporting 2-36
2.9.6. Summary of Preliminary Cost Estimates 2-36
2.10. ARARs 2-36
2.10.1. Chemical-Specific ARARs '. 2-37
2.10.2. Location-Specific ARARs 2-39
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VCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
2.10.3. Action-Specific ARARs 2-39
2.10.4. Other Applicable Standards 2-40
2.11. Statutory Determinations 2-40
2.11.1. Overall Protection of Human Health and the Environment 2-40
2.11.2. Compliance with ARARs 2-41
2.11.3. Short-Term Effectiveness 2-41
2.11.4. Long-Term Effectiveness and Utilization of Permanent
Solutions 2-41
2.11.5. Reduction of Contaminant Toxicity, Mobility, or Volume as a
Principal Element 2-41
2.11.6. Implementability 2-42
2.11.7. Cost Effectiveness 2-42
2.11.8. State Acceptance 2-42
2.11.9. Community Acceptance ; 2-42
3. Responsiveness Summary 3-1
3.1. Organization of the Responsiveness Summary 3-1
3.2. Summary of Public Comments and Responses 3-1
3.2.1. Selected Remedial Action 3-1
3.2.2. General Comments 3-13
References R-l
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UCRLAR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
List of Figures
Figure 1. Location of LLNL Livermore Site and Site 300.
Figure 2. Location of the General Services Area operable unit at Site 300.
Figure 3. Conceptual hydrogeologic model of the General Services Area.
Figure 4. Confirmed chemical release sites in the central GSA.
Figure 5. Confirmed chemical release sites in the eastern GSA.
Figure 6. TCE concentrations in ground water from the shallow aquifer
(Qt-Tnsci) in the central GSA (4th quarter 1995 data).
Figure 7. TCE concentrations in ground water from the Tnbs i regional aquifer
in the central GSA (4th quarter 1995 data).
Figure 8. Total VOC concentrations in ground water in the alluvium (Qal) and
shallow bedrock (Tnbsi) in the eastern GSA (4th quarter 1995 data).
Figure 9. TCE concentrations in ground water from the deeper Tnbsi regional
aquifer in the eastern GSA (4th quarter 1995 data).
Figure 10. Locations of active water-supply wells.
Figure 11. Locations of existing and proposed ground water extraction and
reinjection wells, soil vapor extraction wells and treatment systems.
Figure 12. Total VOC concentrations in ground water in the alluvium (Qal) and
shallow bedrock (TnbS]) in the eastern GSA (4th quarter 1991 data).
Figure 13. TCE concentrations in ground water from the deeper Tnbs! regional
aquifer in the eastern GSA (4th quarter 1991 data).
Figure 14. Schematic of the eastern GSA remediation system for the selected
remedy (Alternative 3b).
Figure 15. TCE concentrations in ground water from the shallow aquifer (Qt-
Tnsc,) in the central GSA (3rd quarter 1992 data).
Figure 16. TCE concentrations in ground water from the Tnbsj regional aquifer
in the central GSA (4th quarter 1991 data).
Figure 17. Schematic of the central GSA remediation system for the selected
remedy (Alternative 3b).
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UCRL-AR-I24061
Final ROD for the GSA Operable Unit, Site 300
January 1997
List of Tables
Table 1. Contaminants of potential concern in ground water in the GSA.
Table 2. Contaminants of potential concern in surface soil (<0.5 ft) in the GSA.
Table 3. Contaminants of potential concern in subsurface soil (>0.5-12.0 ft) in the GSA.
Table 4. Contaminants of potential concern in VOC soil flux in the GSA.
Table 5. Summary of the fate and transport models applied to estimate human
exposure-point concentrations in the GSA OU.
Table 6. Cancer risk and hazard index summary, and reference list for the
GSA OU.
Table 7. Summary of GSA OU remedial alternatives.
Table 8. Comparative evaluation of remedial alternatives for the GSA OU.
Table 9. Chemical-specific ARARs for potential chemicals of concern in
ground water at the GSA OU.
Table 10. Selected remedy (Alternative 3b): Capital costs for source mass
removal and plume migration prevention in the GSA OU.
Table 11. ARARs for the selected remedy at the GSA OU.
Acronyms and Abbreviations
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Acronyms and Abbreviations
For the convenience of the reader, a reference list defining acronyms and abbreviations used
throughout this document is presented after the Tables.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
1. Declaration
1.1. Site Name and Location
The site described in this Record of Decision (ROD) is known as the General Services Area
(GSA) operable unit (OU) located at Lawrence Livermore National Laboratory (LLNL) Site 300,
Tracy, California. This OU is designated as OU-1 in the Site 300 Federal Facility Agreement
(FFA) signed in June 1992.
1.2. Statement of Basis and Purpose
This decision document presents the selected remedial action for the GSA OU at LLNL
Site 300. This remedial action was developed in accordance with the Comprehensive
Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent
practicable, the National Contingency Plan (NCP). This decision is based on the Administrative
Record for this OU. The State of California Department of Toxic Substances Control (DTSC),
Central Valley Regional Water Quality Control Board (CVRWQCB), and the U.S.
Environmental Protection Agency (EPA) Region DC concur with the selected remedy.
1.3. Assessment of the Site
Based on the baseline risk assessment, actual or threatened releases of hazardous substances
at this OU, if not addressed by implementing the response actions selected in this ROD, may
present an imminent and substantial endangerment to public health and welfare, or the
environment.
1.4. Description of the Selected Remedy
In June 1992, a FFA for the LLNL Site 300 Experimental Test Facility was signed by the
regulatory agencies (U.S. EPA Region IX, DTSC, CVRWQCB) and the landowner (U.S.
Department of Energy [DOE]). The FFA defines seven OUs and designates the GSA OU as
OU-1. The GSA OU is located in the southeastern portion of Site 300 and was established to
address soil and ground water contamination in the subsurface immediately beneath and
approximately 2,300 ft downgradient of the GSA facilities. Currently, a stream-lined CERCLA
process is being adopted for Site 300 cleanup. This process will not affect the GSA OU, which
will proceed on the current FFA schedule.
Remedial actions for the GSA OU primarily target trichloroethylene (TCE) and other volatile
organic compounds (VOCs) in ground water and soil beneath the GSA. The risks associated
with subsurface contamination at the GSA OU are: 1) potential ingestion of ground water
containing VOCs, and 2) onsite worker inhalation exposure to TCE volatilizing from subsurface
soil (0.5-12.0 ft) to indoor air within Building 875.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
Three remedial alternatives for the GSA OU were presented in the Final General Services
Area Feasibility Study (Rueth and Berry, 1995). These remedial alternatives were evaluated by
the supervising Federal and State regulatory agencies and presented to the public. DOE and the
regulatory agencies, the U.S. EPA, and the State of California DTSC and CVRWQCB agreed
that Alternative 3b provides the most effective means of remediating VOCs in soil and ground
water to levels protective of human health and the environment. Alternative 3b is presented as
the selected remedy for the GSA OU. The major components of the selected remedy include:
• Monitoring throughout the predicted 55 years of remediation, plus five years of post-
remediation monitoring.
• Contingency point-of-use (POU) treatment for existing offsite water-supply wells.
• Administrative controls to prevent human exposure by restricting access to or activities in
contaminated areas, if necessary.
• Soil vapor extraction (SVE) and treatment in the central GSA dry well source area. SVE
will be conducted to: 1) reduce VOC concentrations in soil vapor to levels protective of
ground water, 2) remediate dense non-aqueous phase liquids (DNAPLs) in the soil, and
3) mitigate VOC inhalation risk inside Building 875.
• Dewatering of the shallow water-bearing zone in the vicinity of the Building 875 dry well
release area to enhance the effectiveness of SVE by exposing a larger soil volume to
vapor flow.
• Extraction and treatment of ground water in the GSA until drinking water standards
(Maximum Contaminant Levels, or MCLs) are reached in both the regional and shallow
aquifers. Modeling indicates ground water extraction will reduce ground water VOC
concentrations in the eastern and central GSA to the remediation goal (MCLs) within 10
and 55 years, respectively.
The 1995 present-worth cost of the selected remedy is estimated to be approximately $18.90
million. This estimate assumes: 1) 10 years of SVE, and 55 years of ground water extraction in
the central GSA, 2) 10 years of ground water extraction in the eastern GSA debris burial trench
area, and 3) 60 years of ground water monitoring. These time and cost estimates do not include
the development, testing, or utilization of any future innovative technologies, which, if available,
could be used to expedite cleanup and/or reduce long-term costs.
DOE and the regulatory agencies will jointly determine the scope and schedule of all
required post-ROD documents and reports (up to the Final Remedial Design document), as well
as schedules for implementing the selected remedy.
1.5. Statutory Determinations
The selected GSA remedial action is protective of human health and the environment and
complies with Federal and State applicable or relevant and appropriate requirements (ARARs).
The selected remedy provides both short- and long-term effectiveness in meeting ARARs and
protecting human health and the environment. This remedy satisfies the statutory preference for
remedies that employ treatment technologies that reduce contaminant toxicity, mobility, or
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UCRL-AR- 124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
volume as a principal element. The remedial action is readily implementable and provides the
most cost-effective means of remediating VOCs in the affected media available at this time.
The supervising Federal and State regulatory agencies participated in the evaluation of the
proposed remedial alternatives and concur with the selected remedy. Public input was
considered and used, as appropriate, in the selection and development of the final remedial
action.
A review will be conducted within five years and every five years after commencement of
the remedial action to ensure that the remedy continues to provide adequate protection of human
health and the environment.
1.6. Acceptance of the Record of Decision by Signatory Parties
Each undersigned representative of a party certifies that he or she is fully authorized to enter
into the terms and conditions of this agreement and to legally bind such party to this agreement.
IT IS SO AGREED:
Daniel D. Opalski Date
Chief, Federal Facilities Cleanup Branch
Superfund Division
U.S. Environmental Protection Agency
Region IX
Barbara Cook, P.E\J Date
Chief, Northern California Coastal Cleanup Operations Branch
California Department of Toxic Substances Control
"2-/S/T7
Jam :s R. Bennett Date
Interim Executive Officer
Slate of California Regional Water Quality Control Board
Central Vallev-R-eeion
fames M. Turner, Ph.D. Date
Manager
Oakland Operations Office
U.S. Department of Energy
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
2. Decision Summary
2.1. Site Name, Location, and Description
Site 300, a DOE-owned experimental test facility operated by the University of California, is
located in the southeastern Altamont Hills of the Diablo Range, about 17 mi east-southeast of
Livermore and 8.5 mi southwest of Tracy, California (Fig. 1). The site is bordered by cattle
grazing land, a California Department of Fish and Game ecological preserve, an outdoor
recreational facility, and a privately owned high explosives (HE) testing facility. For the purpose
of this ROD, it is assumed that Site 300 will remain under the continued control of DOE for the
foreseeable future.
The GSA OU is located in the southeastern part of Site 300, and was established to address
soil and ground water contamination in the subsurface below the OU (Fig. 2).
2.2. Site History and Summary of Enforcement
Prior to the purchase of Site 300 land for development as a DOE experimental test facility in
1953, the GSA was used for cattle ranching and livestock grazing. Since the late 1950s, the GSA
facilities have been used as administration offices and equipment fabrication and repair shops
that support Site 300 activities. Site 300 was in operation prior to the enactment of the Resource
Conservation and Recovery Act of 1976.
Undetermined quantities of solvents containing TCE, a suspected human carcinogen, and
other VOCs were released to the ground as a result of past activities in the craft shops, equipment
fabrication and repair facilities in the GSA, and are in the soil/rock and ground water in the area.
Other chemical compounds commonly detected in soil/rock and ground water in the GSA
include tetrachloroethylene (PCE), 1,2-dichloroethylene (DCE), 1,1-DCE, and freon compounds.
In 1982, DOE discovered contamination at the site and began an investigation under
CVRWQCB guidance. All investigations of potential chemical contamination at Site 300 were
conducted under the oversight of the CVRWQCB until August 1990, when Site 300 was placed
on the National Priorities List. Since then, all investigations have been conducted in accordance
with CERCLA under the guidance of three supervising regulatory agencies: the U.S. EPA
Region IX, the CVRWQCB, and the DTSC. The DOE entered into a FFA with these agencies in
June 1992.
In accordance with CERCLA requirements and the terms of the Site 300 FFA, DOE released
the Final Site-Wide Remedial Investigation (SWRI) report (Webster-Scholten, 1994), the Final
General Services Area Operable Unit Feasibility Study (FS) (Rueth and Berry, 1995) and the
Proposed Plan for Remediation of the Lawrence Livermore National Laboratory Site 300
General Services Area (U.S. DOE/LLNL, 1996). The SWRI documented environmental
investigations that occurred at Site 300 since 1982, and characterized the extent of VOCs in the
subsurface and the Site 300 hydrogeology. The GSA FS developed and evaluated alternatives
for remedial action at the GSA. The SWRI and the FS form the basis for selecting technologies
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UCRL-AR-J2406J Final ROD for the GSA Operable Unit. Site 300 January 1997
to remediate the GSA OU. The Proposed Plan for remediation of the GSA OU summarized site
conditions and remedial alternatives, and presented the preferred remedy.
CERCLA Removal Actions were initiated in the eastern and central GSA in 1991 and 1993,
respectively. To date, 35,387 grams (79 Ib) of VOCs have been removed from the GSA through
ground water and soil vapor extraction as part of these Removal Actions.
2.3. Highlights of Community Participation
The SWRI and the FS for the GSA OU were made available to the public in April 1994 and
October 1995, respectively. The Proposed Plan was released to the public in March 1996. This
ROD presents the selected remedial action for the GSA OU. All documents were prepared in
compliance with CERCLA as amended by SARA. The decision for this site is based on the
Administrative Record, which is available at the Information Repository at the LLNL Visitors
Center and the Tracy Public Library.
A public review and comment period on the preferred remedial alternative began April 10,
1996, and ended May 10, 1996. Interested members of the public were invited to review all
documents and comment on the considered remedial alternatives by writing to the Site 300
Remedial Project Manager or by attending a public meeting on April 24, 1996, at the Tracy Inn
in Tracy, California. At this meeting, representatives from DOE, University of California,
U.S. EPA, and the State of California discussed the proposed remediation plan and addressed
public concerns and questions. Questions and comments from the public are presented and
addressed in the Responsiveness Summary of this ROD.
2.4. Scope and Role of the GSA OU
The Site 300 FFA defines the following seven OUs at Site 300:
• OU-l.GSA.
• OU-2, Building 834.
• OU-3, Pit 6.
• OU-4, HE Process Area Building 815.
• OU-5, Building 850/Pits 3 and 5.
• OU-6, Building 854.
• OU-7, Building 832 Canyon.
• OU-8, Site 300 Monitoring.
Investigations at the GSA OU address VOCs in soil/rock and ground water released to the
environment as a result of past activities in the GSA craft shops, and equipment fabrication and
repair facilities. The principal potential threats to human health and the environment are:
1) ingestion of VOCs in ground water, and 2) exposure to VOC vapors volatilizing from shallow
soil into Building 875.
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VCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
This ROD addresses both the potential human health ingestion risk posed by VOCs in ground
water, as well as the inhalation risk posed by VOCs in the vadose zone at the GSA OU. The
purpose of the selected remedy is to protect human health and the environment by reducing VOC
concentrations in soil vapor and ground water and controlling VOC migration.
2.5. Site Characteristics
Since environmental investigations began at the GSA in 1982, 75 exploratory boreholes have
been drilled and 98 ground water monitor wells have been completed. Details of the geology
and hydrogeology of the GSA OU, as well as environmental investigations conducted in this OU
are presented in Chapter 14 of the Site 300 SWRI. Three water-bearing zones or hydrogeologic
units have been identified (Fig. 3):
• Qt-Tnscj Hydrogeologic Unit: .This shallow water-bearing zone occurs beneath the
central GSA portion of the OU and is composed of stratigraphic units Qt (terrace
alluvium), Tnbs2 (Neroly Formation-Upper Blue Sandstone), and Tnsci (Neroly
Formation-Siltstone/Claystone). Depending on topography, depth to water is
approximately 10 to 20 ft beneath the ground surface. As a result of past releases, this
shallow aquifer contains TCE and other VOCs. The VOC plume in this shallow aquifer
is separated from the regional aquifer by a 60- to 80-ft thick aquitard (Tnsci) in most of
the central GSA. Ground water data indicate that the VOC plume in the shallow aquifer
has not affected the regional aquifer in this area. Ground water in this shallow aquifer
flows south-southeast with an estimated flow velocity of 0.09 to 3 ft/day.
• Tnbsj Hydrogeologic Unit (Regional Aquifer): The regional aquifer occurs in the lower
Neroly Formation (Tnbsj). This aquifer is encountered 35 to 145 ft below the ground
surface under confined to semi-confined conditions in the central GSA. Ground water
flow in this unit is to the south-southeast at a flow velocity of 0.3 ft/day.
• Qal-Tmss Hydrogeologic Unit: This hydrogeologic unit is composed of the stratigraphic
units: Qal (alluvium), Tnscj, Tnbsj, and Tmss (Cierbo Formation). For the most part, the
Tnsci aquitard is absent in the eastern GSA, and the shallow water-bearing zone (Qal) is
in hydraulic communication with the underlying regional aquifer (Tnbsi). As a result,
some contamination has migrated downward from the shallow-water bearing zone into
the regional aquifer. Ground water flow in the alluvium (Qal) and shallow Tnbsi
bedrock is eastward, turning north to follow the trend of the valley. Although the flow
velocity is dependent on local hydraulic conductivity, the maximum flow velocity is
estimated to be about 200 to 1,200 ft/yr.
2.5.1. Chemical Releases
Historical information and analytical data suggest that VOCs, in the dissolved form and/or as
DNAPLs, were released to the ground in wastewater from the craft and repair shops, as
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leaks/spills from solvent storage tanks or drums, and associated with debris buried in trenches in
the eastern GSA in the 1960s and 1970s. These releases include:
• VOCs in rinse-, process-, and wash-water discharged to four dry wells from the central
GSA craft and repair shops. Based on soil and ground water analytical data, the greatest
VOC mass is concentrated in the vicinity of the Building 875 former dry wells.
• VOCs released to the ground from a decommissioned drum storage rack north of
Building 875.
• VOCs in rinse water discharged from a steam cleaning/sink area east of Building 879.
• VOCs associated with craft shop debris buried in trenches in the eastern GSA.
The confirmed release sites for the central and eastern GSA are shown in Figures 4 and 5.
The quantity of TCE released in these areas greatly exceeds that of other VOCs.
2.5.2. VOCs in Ground Water
TCE is the most prevalent VOC in ground water, typically comprising 85 to 95% of the total
VOCs detected. Other VOCs that have been detected include PCE, 1,2-DCE, 1,1-DCE, 1,1,1-
trichloroethane, acetone, benzene, bromodichloromethane, chloroform, ethylbenzene, Freon 113,
toluene, and xylenes (total isomers) (Table 1).
Detected concentrations of ethylbenzene, toluene, and xylene have decreased over time.
Toluene, ethylbenzene, and xylenes have not been detected in ground water from any GSA wells
in over 2.5 years. The last detections of these compounds occurred in 1994 when toluene was
detected in well W-875-02 at a concentration of 0.5 u,g/L and xylene was detected in well W-7N
at a concentration of 0.96 u,g/L. No toluene, ethylbenzene, or xylenes have been detected in any
other GSA wells for 3.5 years or more. Therefore, these constituents are no longer considered
contaminants of concern. The CVRWQCB believes that it is appropriate to continue to monitor
for these constituents, but at a reduced frequency. The extent and frequency of monitoring for
these constituents will be addressed in the Remedial Design document.
The highest ground water VOC concentrations in the central GSA have been detected in the
vicinity of former dry well pad south of Building 875 (Figs. 4 and 6). TCE has been detected in
ground water in concentrations up to 240,000 micrograms per liter (u\g/L) in a bailed ground
water sample collected from well W-875-07 in March 1993. This concentration suggests that
TCE is present as residual DNAPL in the subsurface. As of third quarter 1994, the maximum
TCE concentration in ground water samples collected from the Building 875 dry well pad area
was 10,000 jig/L in well W-7I (Fig. 6). In general, if a ground water VOC concentration is 1 to
10% of the solubility of that VOC in ground water, a DNAPL may be present. Because the
aqueous solubility of TCE is 1,100,000 jig/L, TCE concentrations in the range of 11,000 to
110,000 Hg/L or greater may indicate DNAPL. The only wells in the GSA where ground water
sample data indicate the possible presence of DNAPLs (TCE concentrations > 11,000 u.g/L) are
wells W-875-07, -08, -09, -10, -11, -15, and W-7I. As shown in Figure 6, these wells are all
located in the Building 875 dry well pad area in the central GSA. The source of DNAPLs in this
area was the waste water disposed in the two former dry wells, 875-S1 and 875-S2, located south
of Building 875 (Fig. 4). Based on soil sample data from boreholes drilled prior to installation of
the dry well pad wells, the bulk of TCE contamination in the dry well pad area is concentrated at
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
a depth of 20 to 35 ft near the contact between the Tnb$2 water-bearing zone and the underlying
Tnsci confining layer. These data support a DNAPL-type scenario where TCE, which is denser
than water, would tend to sink to the lowest point possible in a water-bearing unit, such as the
contact between the water-bearing zone and an underlying confining layer that prevents the
further downward migration of contaminants.
No other wells in the GSA have contained VOCs in ground water in concentrations
indicative of DNAPLs, including wells located at other source areas and the two wells (W-7F
and W-875-03) located within 50 to 75 ft of the dry well pad. We have therefore concluded that
the DNAPLs are confined to the Building 875 dry well pad area in the central GSA.
As shown in Figure 6, a VOC ground water plume in the Qt-Tnscj shallow aquifer extends
from the Building 875 dry well pad and Building 872 and Building 873 dry wells into the Corral
Hollow Creek alluvium. There is a smaller ground water plume with significantly lower VOC
concentrations to the north associated with the drum storage rack and steam cleaning release
sites. Based on ground water data collected from the Tnbsj regional aquifer, the VOC plumes
appear to be confined to the Qt-Tnscj hydrogeologic unit in this area, where the Tnsci confining
layer prevents the downward migration of contaminants. West of the sewage treatment pond,
TCE has been detected in ground water in the regional aquifer (Fig. 7) where the Tnsci confining
layer is absent. The low TCE concentrations have generally been decreasing in the regional
aquifer in this area since 1990.
In the eastern GSA, the highest VOC concentrations in ground water occur in the vicinity of
the debris burial trench area (Fig. 8). TCE has been detected in ground water in concentrations
up to 74 ^ig/L in this area. A VOC ground water plume extends eastward from the debris burial
trench area and has migrated northward in the Corral Hollow alluvium. The plume with total
VOC concentrations exceeding 5 \ig/L currently extends approximately 550 ft from the debris
burial trench release area. TCE has also been detected at low concentrations in ground water in
the regional aquifer in the vicinity of the debris burial trenches (Fig. 9). TCE in the regional
aquifer in this area is generally limited to portions of the regional aquifer which directly underlie
the contaminated shallow water-bearing zone. The maximum VOC concentrations in ground
water as of fourth quarter 1995 were 20 |J.g/L in the shallow water-bearing zone and 19 p.g/L in
the regional aquifer.
Further details on the extent of VOCs in ground water in the GSA can be found in
Section 14-4.5, Chapter 14 of the Site 300 SWRI (Webster-Scholten, 1994), and Section 1.4.7 of
the GSA FS (Rueth and Berry, 1995).
2.5.3. VOCs in Soil/Rock
The highest TCE concentrations in soil/rock (up to 360 milligrams per kilogram [mg/kg]) in
the central GSA were detected in the vicinity of the Building 875 former dry wells 875-S1 and
875-S2 at a depth of 20 to 35 ft near the contact between the Tnbs2 water-bearing zone and the
underlying Tnscj confining layer. Also, low concentrations of VOCs were detected in soil/rock
samples collected from boreholes in the vicinity of the other four confirmed release sites in the
central GSA: the decommissioned solvent drum rack, dry wells 872-S and 873-S, and the
Building 879 steam-cleaning facility. VOC concentrations ranged from 0.0002 mg/kg to 0.9
mg/kg in these samples collected in 1989.
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TCE, PCE and 1,2-DCE have been detected in concentrations up to 0.19 mg/kg in borehole
soil samples collected in 1989 in the vicinity of the debris burial trenches in the eastern GSA.
Further details on the extent of VOCs in soil/rock in the GSA are described in Section 14-4.3,
Chapter 14 of the Site 300 SWRI (Webster-Scholten, 1994) and Section 1.4.6 of the GSA FS
(Rueth and Berry, 1995).
2.5.4. VOCs in Soil Vapor
Extensive soil vapor surveys, including both active and passive techniques, were conducted
between 1988 and 1994 to: 1) assist in the identification of release sites, 2) determine the extent
of VOC contamination, and 3) monitor the progress of soil vapor remediation efforts.
Further details on the extent of VOCs in soil vapor in the GSA can be found in
Section 14-4.2, Chapter 14 of the Site 300 SWRI (Webster-Scholten, 1994), and Section 1.4.3 of
the GSA FS (Rueth and Berry, 1995).
2.6. Risk Assessment
The baseline risk assessment provides the basis for taking action and identifies the potential
exposure pathways that need to be addressed by the remedial action. It serves as the baseline to
indicate what potential risks might exist if no action were taken at the site. This section of the
ROD reports the results of the baseline risk assessment conducted for this site. Additional details
may be found in Chapter 6 of the Site 300 SWRI (Webster-Scholten, 1994), and Section 1.6 of
the GSA FS (Rueth and Berry, 1995).
The baseline risk assessment evaluated potential present and future public health and
ecological risks associated with environmental contamination in the GSA OU, using the
assumption that no cleanup or remediation activities would take place at the site. Selection of a
specific remediation strategy is based in part on the extent to which it can reduce potential public
health and ecological risks.
The baseline risk assessment presented in the SWRI consists of six components:
• Identification of chemicals of potential concern.
• Identification of the contaminated environmental media.
• Estimation of potential exposure-point concentrations of contaminants.
• Human exposure and dose assessment.
• Toxicity assessment.
• Risk characterization.
Each of these components are summarized in the following sections. Additional details are
available in the Site 300 SWRI and in the GSA FS.
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2.6.1. Identification of Chemicals of Potential Concern
Tables 1 through 4 present the chemicals of potential concern identified in the GSA OU.
Details of the methodology used to identify these contaminants are described in the Site 300
SWRI (Webster-Scholten, 1994).
2.6.2. Identification of Contaminated Environmental Media
Based on the assessment of the nature and extent of contamination obtained during site
characterization, contaminants of potential concern were identified in different environmental
media in the GSA OU: ground water, surface soil, subsurface soil, and soil vapor (Tables 1
through 4, respectively). The 95% upper confidence limit (UCL) of the mean concentration and
exposure-point concentrations of each contaminant are listed in Table 5.
2.6.3. Estimates of Potential Exposure-Point Concentrations
Conceptual models were developed to identify the probable migration processes and routes
of the chemicals of concern from release sites and source media in the GSA OU to selected
potential exposure points. The conceptual models provided the basis for selection of the
quantitative models used to generate estimates of contaminant release rates and potential
exposure-point concentrations. The exposure-point concentrations were used to estimate the
magnitude of potential exposure to contaminants in the baseline risk assessment. The release
areas, migration processes, and exposure points identified in the GSA OU are given in Table 5.
In addition, this table lists the mathematical models used to estimate contaminant migration rates
and the calculated exposure-point concentrations for the chemicals of concern in each
environmental medium.
Direct measurements of VOC soil flux were obtained in the GSA that were used in a
mathematical model to estimate exposure-point concentrations of contaminants in the
atmosphere when VOCs volatilize from subsurface soil in the vicinity of three exposure
locations in the GSA OU: 1) the Building 875 dry well area, 2) the central GSA, and 3) the
eastern GSA. A mathematical model was applied, using subsurface soil (0.5 to 12.0ft) VOC
concentrations in the vicinity of the Building 875 dry well pad, to estimate the potential
exposure-point concentrations of contaminants in indoor air of Building 875 when VOCs
volatilize from subsurface soil underneath the building and diffuse into the building.
Measurements of actual VOC concentrations inside Building 875 were not conducted or used in
the estimate of exposure-point concentrations in indoor air as the work activities which still
occur in Building 875 involve the use of VOC-containing solvents. Therefore, it would be
difficult, if not impossible to distinguish between VOC vapors migrating from the subsurface
through the concrete floor and those present in indoor air as a result of current work activities
utilizing solvents. As a result, we took a health conservative approach and utilized soil sample
data from the Building 875 dry well pad approximately 35 ft from the building to calculate
exposure-point concentrations inside Building 875.
In addition, estimates were made of the concentrations of surface soil (< 0.5 ft) contaminants
that are bound to resuspended particles throughout the OU. The 95% UCLs of the mean
contaminant concentration in the surface soil, and site-specific data on total resuspended
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participates were used to estimate the concentration of surface soil contaminants bound to
resuspended particles throughout the OU. For direct dermal contact and incidental ingestion, the
exposure-point concentrations of contaminants in surface soil are the same as the 95% UCLs of
the mean concentration of the chemicals.
The fate and transport of VOCs in ground water were considered for both the central and
eastern GSA, as well as a combined central and eastern GSA plume. For the central GSA,
exposure-point concentrations were estimated at the site boundary and then modeling was used
to estimate exposure-point concentrations at the California Department of Forestry water-supply
well, CDF-1, located approximately 300 ft southeast of the Site 300 boundary. For the eastern
GSA, exposure-point concentrations were estimated for a theoretical well at the site boundary
and for two plumes commingling at well CDF-1; these concentrations were modeled to
downgradient water-supply well SR-1 (Fig. 10).
2.6.4. Human Exposure and Dose Assessments
Exposure scenarios and pathway exposure factors (PEFs) used to assess the magnitude of
potential human exposure and dose are described below.
2.6.4.1. Exposure Scenarios
The exposure scenarios used to evaluate potential adverse health effects associated with
environmental contamination in the GSA OU were developed based on assumptions about
present and future uses of the site and lands in the immediate vicinity.
Two principal scenarios were developed to evaluate potential human exposure to
environmental contaminants in the GSA OU. The first of these scenarios pertains to adults
working in the GSA OU. This scenario addresses potential health risks attributable to
contaminants in subsurface soil and surface soil, where an adult on site (AOS) is presumed to
work in the immediate vicinity of the contamination over their entire period of employment at
the site (25 years). Subsurface soil contaminants can volatilize into air, where they may be
inhaled by individuals who work in the vicinity of the contamination. Surface soil contaminants
bound to resuspended soil particulates may also be inhaled by individuals in the course of work-
related activities at the site. In addition, we evaluated AOS exposure as a consequence of dermal
absorption and incidental ingestion of contaminants on surface soil.
The second scenario pertains to residential exposures (RES), which are associated with use of
contaminated ground water from: 1) theoretical wells installed at the central and eastern GSA
site boundaries, 2) well CDF-1, and 3) well SR-1. The identification and selection of exposure
pathways related to residential use of contaminated ground water were based on the assumption
that well water will be used to supply all domestic water needs, such as those associated with
showering or bathing, cooking, dishwashing, and laundry. We also assumed that contaminated
ground water will be used to irrigate home gardens, and will be supplied to dairy and beef cattle
raised for domestic consumption. Accordingly, we evaluated potential residential exposure to
contaminants in ground water at theoretical wells and existing wells CDF-1 and SR-1 due to:
1) direct ingestion of water, 2) inhalation of VOCs that volatilize from water to indoor air,
3) dermal absorption of contaminants while showering or bathing, 4) ingestion of fruits and
vegetables grown using contaminated ground water, and 5) ingestion of meat and milk from
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homegrown beef and dairy cattle supplied with contaminated ground water. For the purpose of
the risk assessment, we assume residents could be exposed to contaminants in ground water for
30 years.
2.6.4.2. Pathway Exposure Factors
To estimate the magnitude of potential human exposure to contaminants in the GSA OU, we
developed PEFs, which convert the exposure-point concentrations of contaminants into estimates
of average contaminant intake over time (the chronic daily intake, or GDI). These PEFs are
based on a series of reported and/or assumed parameters regarding current and potential land use
patterns in and around the GSA OU, residential occupancy patterns, and length of employment.
PEFs also account for a number of physiological and dietary factors such as the daily ingestion
rates of water and homegrown fruits, vegetables, beef, and milk; daily breathing rate; and surface
area of exposed skin.
Reference documents for PEF data that were used to evaluate potential adult onsite and
residential exposure to contaminants and summary values are listed in Table 6.
2.6.5. Toxicity Assessment
For each location with environmental contamination, we began by identifying those
chemicals of concern that are classified by the U.S. EPA (U.S. EPA, 1992a) or by the State of
California EPA (1992) as carcinogens. This classification is based on data from epidemiological
studies, animal bioassays, and in vivo and in vitro tests of genotoxicity.
2.6.5.1. Cancer Potency Factors
The Cancer Potency Factors (CPFs) used in our estimations of cancer risk were obtained
from values published in either the Integrated Risk Information System (IRIS) (U.S. EPA,
1992b), the Health Effects Assessment Summary Tables (U.S. EPA, 1992a,c), or by the State of
California, EPA (1992). CPFs for TCE and PCE were also provided by Region IX of the U.S.
EPA (1993a). All CPFs were derived using versions of the linearized, multistage dose-response
model (U.S. EPA, 1989a,b); generally, the dose- and tumor-incidence data used in the model are
from animal bioassays. For contaminants of potential concern at Site 300, the exceptions are
cadmium, benzene, and beryllium, where human tumor data are available. The model calculates
the potential increased cancer risk, where increased risk is linearly related to dose for low-dose
levels typical of environmental exposure. Use of animal bioassay data to predict human
tumorigenic response assumes that animals are appropriate models of human carcinogenic
response, and that the dose-response relationships observed in high-dose animal bioassays can be
extrapolated linearly to the low doses generally associated with human exposure to
environmental contaminants. When CPFs were available for a particular contaminant from both
a U.S. EPA source and the State of California, the highest potency values were used.
Reference documents for CPFs (slope factors) used to calculate cancer risks in our evaluation
are listed in Table 6.
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2.6.5.2. Reference Dose
The reference doses (RfDs) used to evaluate potential noncarcinogenic adverse health effects
were based, when possible, on long-term (i.e., chronic) exposures, and were derived by dividing
an experimentally-determined no-observed-adverse-effect-level or lowest-observed-adverse-
effect-level (each has units of mg/[kg • d]) by one or more uncertainty factors (U.S. EPA,
1992a,b,c). Each of these uncertainty factors has a value that ranges from 1 to 10 (U.S. EPA,
1992a,b,c). Pathway-specific RfDs were used, when available (U.S. EPA, 1992a,b,c; Cal-EPA,
1992), to calculate a corresponding Hazard Quotient (HQ). If pathway-specific RfDs were not
available, the published RfDs (typically developed for oral exposures) were used to calculate an
HQ for all exposure pathways.
Reference documents and reference doses used to calculate noncancer hazard indices in our
evaluation are listed in Table 6.
2.6.6. Risk Characterization
The risk assessment was performed in accordance with Risk Assessment Guidance for
Superfund (U.S. EPA, 1989a,b). Carcinogenic risks, an evaluation of potential noncarcinogenic
exposure health hazards, and the additivity of response are described below.
2.6.6.1. Carcinogen ic Risks
For carcinogens, we calculated the potential incremental cancer risk associated with long-
term exposure to chemicals in surface soil, subsurface soil, and ground water. For each chemical
at each exposure location, the total risk attributable to that chemical was estimated by
multiplying each pathway-specific intake (e.g., the dose due to ingestion of water or to inhalation
of contaminants that volatilize from water to indoor air) by the corresponding pathway-specific
CPF. The products of each pathway-specific intake and pathway-specific CPF were summed to
obtain the potential incremental cancer risk for a specific chemical. Parallel sets of calculations
were completed for all chemicals at each exposure location, then values of chemical-specific risk
from all chemicals were summed to yield an estimate of total incremental risk for exposures
associated with a given location.
2.6.6.2. Evaluation of Hazard from Exposure to Chemicals that Cause
Noncancer Health Effects
For chemicals of potential concern that are not classified as carcinogens, and for those
carcinogens known to cause adverse health effects other than cancer, the potential for exposure
to result in noncarcinogenic adverse health effects was evaluated by comparing the GDI with a
RfD. When calculated for a single chemical, this comparison yields an HQ. For each chemical
at each location, pathway-specific HQs were summed (where applicable) to obtain an HQ
estimate for a given chemical. We then summed all HQs from all chemicals to yield a hazard
index (HI) estimate for exposures associated with a given location.
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2.6.6.3. Additivity of Response
In every location at or near the GSA OU where cancer risk and noncancer HQs were
calculated, GDIs were estimated for exposures attributable to multiple pathways for each of
several contaminants. As noted previously, the total potential cancer risk and/or total HI were
estimated by summing risk or HQs for all contaminants at a given location, where each
chemical-specific estimate of risk or hazard represents exposures from multiple pathways.
Implicit in the summation of risk and hazard is the assumption that the effects of exposure to
more than one chemical are additive. This simplifying assumption does not consider similarities
or differences in target organ toxicity, mechanism(s) of action, or the possibility of synergistic or
antagonistic effects of different chemicals in the mixture.
2.6.7. Summary of Human Health Baseline Risks and Hazards Associated
with Contaminants
Estimated baseline risks and hazards for the GSA OU were evaluated for adults on site
exposures and residential exposures, as well as additive potential risk. These are described
below, followed by a brief discussion of uncertainty.
2.6.7.1. Adult Onsite Exposures
The AOS exposure Scenario addresses potential health risk attributable to contaminants in
soil, where an AOS is presumed to work in the immediate vicinity of the contamination over the
entire period of employment at the site (25 years).
v
We evaluated potential AOS exposure to contamination by calculating the associated risk and
hazard for two scenarios. The first of these scenarios pertains to potential AOS exposure to
contaminated subsurface soil through inhalation of VOCs volatilizing from subsurface soil to air.
The second scenario pertains to potential AOS exposure to contaminated surface soil from
inhalation of resuspended particulates, dermal absorption of contaminants following direct
contact with contaminated soil, and incidental ingestion.
Risk and hazard associated with AOS exposure to contaminated subsurface soil through
inhalation of VOCs volatilizing from subsurface soil (0.5 to 12.0 ft) to ambient air was evaluated
in the vicinity of three exposure locations in the GSA OU: 1) the Building 875 dry well area,
2) the central GSA, and 3) the eastern GSA. Individual potential excess lifetime cancer risks
were 2 x 10~7 for the Building 875 area, 7 x 10~7 for the central GSA, and 2 x 10~7 for the
eastern GSA. The estimated noncancer His were 6.2 x 10~3 for the Building 875 area,
1.2 x 10-3 for the central GSA, and 1.3 x 10-3 for the eastern GSA.
The potential excess lifetime cancer risk and noncancer His for the AOS exposure to
contaminants volatilizing from subsurface soil to ambient air are within the acceptable range
(cancer risk < 1Q-6 and HI <1) specified by the NCP (U.S. EPA, 1990a).
Risk and hazard were also evaluated for AOS inhalation exposure to VOCs volatilizing from
contaminated subsurface soil underneath Building 875 and diffusing into the building. The
exposure scenario for an AOS working inside Building 875 resulted in estimates of individual
potential excess lifetime cancer risk (1 x 10~5) and noncancer HI (3 x 10~')- While the
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noncancer HI for this scenario is within acceptable limits (HI <1), the potential excess lifetime
cancer risk is within the range (between 10"4 and lO"6) where risk management measures are
necessary.
The baseline evaluation of risk and hazard associated with AOS exposure to surface soil
contaminants yielded estimates of individual excess lifetime cancer risk of 2 x 10~7 for
inhalation of resuspended particulates and 2 x 10~10 for ingestion and dermal absorption of
surface soil contaminants. The corresponding His are 5.6 x 10~5 for inhalation and 8.5 x 10~3
for ingestion and dermal absorption. The potential excess lifetime cancer risk and noncancer His
for the AOS exposure to surface soil contaminants are within the acceptable range (cancer risk of
<10-6 and HI <1) specified by the NCP (U.S. EPA, 1990a).
Reference documents for calculations and estimates of potential cancer risk and hazard index
and the results are summarized in Table 6.
2.6.7.2. Additive Risk and Hazard for Adults Onsite
Adults working outdoors in the GSA OU could be exposed simultaneously to contaminants
in surface soil (by inhalation of resuspended particulates, and ingestion and dermal absorption of
surface soil contaminants) as well as by inhalation of the VOCs that volatilize from subsurface
soil. The vicinity of the central GSA was selected for our calculations of additive risk and HI
associated with AOS exposures because our calculations indicated higher levels of cancer risk
and HI for this location than for exposures associated with the Building 875 dry well area and the
eastern GSA. Because the Building 875 dry well area, central GSA, and eastern GSA are
separated by approximately 200 ft, we did not examine concurrent exposures to VOCs from the
three sources.
Table 6 presents the potential additive individual excess lifetime cancer risk and HI estimates
for AOS exposures in the GSA OU. The values given in Table 6 indicate an estimated total
additive cancer risk of 9 x IQ-7 and a total additive HI of 9.7 x 10~3.
The potential additive individual excess cancer risk and additive noncancer His for the AOS
exposure in the GSA OU are within the acceptable range (cancer risk <10~6 and HI <1) specified
by the NCP (U.S. EPA, 1990a).
2.6.7.3. Residential Exposures
Risk and hazard were evaluated for potential RES use of contaminated ground water at:
1) hypothetical wells located at the site boundary near the Building 875 dry wells and the eastern
GSA debris burial trenches, and 2) at existing water-supply wells CDF-1 and SR-1.
We calculated the risk and hazard associated with potential RES use of contaminated ground
water from a hypothetical water-supply well located at the site boundary nearest to the
Building 875 dry wells. The individual excess lifetime cancer risk attributable to the potential
use of ground water at this location is 7 x 10~2, and the corresponding HI is 560. These values
estimate that if ground water at the site boundary in the central GSA were to be used for
residential purposes on a regular basis for 30 years, there would be an unacceptable incremental
excess cancer risk and unacceptable noncancer health effects.
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We also evaluated risk and hazard associated with potential residential use of contaminated
ground water at the site boundary nearest to the eastern GSA debris burial trenches. The
individual excess lifetime cancer risk attributable to the potential use of ground water at this
location is 5 x 10~5, and the corresponding HI is 5 x lO"1. In addition, we calculated the risk
and hazard associated with potential use of contaminated ground water at two offsite locations,
wells CDF-1 and SR-1. The individual excess lifetime cancer risks attributable to the potential
use of ground water at these locations are 1 x 10~5 and 2 x 10~5, respectively. The
corresponding His are 1.4 x 1(H and 1.6 x 10~1. While the noncancer HI for these scenarios are
within acceptable limits (HI <1), the potential excess lifetime cancer risk is within the range
(between 10"4 and lO"6) where risk management measures are necessary (U.S. EPA, 1990a).
Reference documents for calculations and estimates of potential cancer risk and hazard index
and the results are summarized in Table 6.
2.6.7.4. Uncertainty in the Baseline Public Health Assessment
Uncertainties are associated with all estimates of potential carcinogenic risk and
noncarcinogenic hazard. For example, the exposure parameters recommended by the U.S. EPA
(1990b; 1991) are typically obtained from the 90th or 95th percentile of a distribution; they are
not necessarily representative of an average individual or of average exposure conditions.
Consequently, use of multiple upper-bound parameters may contribute to overly conservative
estimates of potential exposure, risk, and hazard.
In addition, the total cancer risk and/or total HI was calculated by summing risk of HQs for
all contaminants at a given location, where each chemical-specific estimate of risk or hazard
represents exposures from multiple pathways. Implicit in the summation of risk and hazard, is
the assumption that the effects of exposure to more than one chemical are additive. This
simplifying assumption does not consider similarities or differences in target organ toxicity,
mechanism(s) of action, or the possibility of synergistic or antagonistic effects of different
chemicals in the mixture.
Other uncertainties associated with the estimates of risk and hazard are OU-specific and are
related to assumptions made in the modeling conducted to provide exposure-point
concentrations, which were subsequently used to calculate risk and hazard. Modeling was
conducted to provide estimates of exposure-point concentrations that were used to calculate risk
and hazard associated with exposure to contaminated ground water migrating from the central
and eastern GSA source areas to potential receptor wells CDF-1, SR-1 and at hypothetical wells
at the site boundary as discussed in Section 2.6.3.
The following assumptions were made in the ground water modeling, which may result in
uncertainties associated with the risk and hazard estimates:
1. The health conservative assumption was made that the 95% UCL for TCE at the central
and eastern GSA source areas will reach the site boundary.
2. Human exposure was assumed to result from potentially contaminated ground water if a
hypothetical well were to be installed .at the site boundary in the near future and was used
for residential purposes on a regular basis. However, water in this area is not currently
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used for domestic purposes, and Removal Action remediation activities are currently
underway to remove ground water contaminants.
In addition, the private land directly adjacent to the GSA source areas is open rangeland,
and we are not aware of any plans to build homes or install wells there in the near future.
3. The source terms for plume migration in both the central and eastern GSA were assumed
to remain constant despite ongoing and planned remediation activities in the GSA. Any
change in the source term would result in a direct proportional change in the exposure-
point concentration used to calculate risk and hazard.
4. Both the source concentration and volumetric flow rate, which define the source term,
were estimated at the high end of their expected range.
5. A dilution factor was applied to well CDF-1 to estimate exposure-point concentrations
based on contaminant concentrations detected in different water-bearing zones from
which well CDF-1 pumps water. Changes in the dilution factor would cause a direct
proportional change in the estimated TCE exposure-point concentration used to calculate
risk and hazard.
6. Other assumptions were made to define model parameters such as porosity, ground water
velocity, dispersivity ratio, and TCE decay half-life used in modeling. The sensitivity of
the predicted maximum exposure-point concentration to these input parameters is
discussed in Appendix P-20 of the Site 300 SWRI.
The cumulative excess cancer risk calculated for Building 875 indoor air was based on VOC
concentrations from soil samples collected from the vicinity of the Building 875 dry well pad
prior to startup of the SVE system. It is likely, due to ongoing soil remediation activities through
SVE, that current VOC soil concentrations are lower than what was used to calculate excess
cancer risk in the baseline risk assessment. In addition, Building 875 is located approximately
35 ft from the dry well pad source area. Therefore, the soil concentration and resulting soil
vapor concentrations under Building 875 are likely to be lower than those used to calculate the
inhalation risk inside Building 875.
2.6.8. Summary of the Baseline Ecological Assessment
The baseline ecological assessment, conducted to evaluate the potential for adverse impact to
plants and animals from long-term exposure to contaminants in the GSA OU, determined that
VOCs do not pose ecological risk in this area. This determination was based on estimates of
potential hazard from exposure to contaminants that were calculated for mammal and aquatic
species that could potentially inhabit this area, as well as biological surveys conducted to
determine which species actually inhabit or migrate through the GSA.
A detailed discussion of the baseline ecological assessment can be found in Section 1.6.4.1 of
the GSA FS (Rueth and Berry, 1995).
2.7. Description of Remedial Action Alternatives
The FS for the GSA OU presented three remedial action alternatives to address 1) potential
risk posed by ingestion of VOCs in ground water, and 2) potential VOC inhalation risks inside
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Building 875. The three remedial action alternatives are summarized in Table 7. It should be
noted that the estimated costs for all alternatives presented in this ROD are lower than the cost
estimates presented in the GSA FS and Proposed Plan. This is due to subsequent modifications
to the 1) contingency point-of-use treatment component based on negotiations with the well
owner, and 2) ground water monitoring component based on changes made to the eastern and
central GSA treatment facility monitoring program permit requirements.
2.7.1. Alternative 1—No Action
A no-action alternative is required by CERCLA as a basis from which to develop and
evaluate remedial alternatives and is the postulated basis of the baseline risk assessment. Under
a no-action response, all current remedial activities in the GSA OU would cease. However, the
following activities would be performed:
• Monitoring of VOCs in ground water, reporting, maintenance, database management, and
quality assurance/quality control (QA/QC).
• Administrative controls including restricting access to or activities in certain areas of
contamination, as necessary.
Modeling indicates that ground water VOC concentrations would be reduced to drinking
water standards through natural attenuation and degradation after 75 years under the
Alternative 1 scenario. Ground water monitoring would be conducted for the 75-year period
plus five years of post-"remediation" monitoring.
The estimated 80-year present-worth cost of Alternative 1 is $3.47 million. Present-worth
cost analysis is a method of evaluating total costs (i.e., the cost of each remedial alternative) for
projects that vary in duration by discounting all costs to a common base year (1995) to adjust for
the time value of money. The present-worth cost represents the amount of money, which if
invested in the initial year (1995) of the remedial action and dispersed over the life of the project,
would be sufficient to cover all associated costs.
2.7.2. Alternative 2—Exposure Control
The objective of Alternative 2 is to protect human health by preventing human exposure to
TCE and other VOCs through ingestion of ground water from existing water-supply wells by
reducing VOC concentrations in water from these wells to drinking water standards (MCLs)
through POU treatment. Drinking water standards and MCLs are discussed in Section 2.10.1.
Hereafter, drinking water standards will be referred to as MCLs throughout this ROD.
Alternative 2 includes:
• Monitoring and administrative control components of Alternative 1.
• Contingency POU treatment for three offsite water-supply wells: CON-1, CDF-1, and
SR-1 (Fig. 10).
As with Alternative 1, reduction of VOC concentrations in ground water through natural
attenuation and degradation would take approximately 75 years under the Alternative 2 scenario.
Ground water monitoring would be conducted for the 75-year period plus five years of
post-"remediation" monitoring.
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The present-worth cost of Alternative 2 is $3.69 million.
2.7.3. Alternative 3—Source Mass Removal and Ground Water Plume
Control
The objectives of Alternative 3 are to provide increased protection of human health and the
environment by: 1) reducing VOC concentrations in ground water to MCLs, 2) reducing
residual VOC (DNAPL) mass/volume, 3) reducing VOC concentrations in soil vapor to levels
protective of ground water, and 4) mitigating VOC inhalation risk inside Building 875. These
objectives will be accomplished through VOC mass removal from contaminant source areas and
plume migration control.
Alternative 3 includes all the elements of Alternatives 1 and 2 and adds ground water and soil
vapor extraction to remove TCE and other VOCs from ground water, soil and rock. Alternative
3 is divided into two scenarios: Alternatives 3a and 3b. Both are the same with respect to the
objective and method of subsurface soil/rock remediation, but differ in their ultimate objectives
for ground water remediation. Both Alternative 3a and 3b include:
• All elements of Alternatives 1 and 2.
• Soil vapor extraction and treatment in the central GSA dry well source area.
• Ground water extraction and treatment in the central and eastern GSA.
Under both Alternatives 3a and 3b, DOE would continue to operate the existing soil vapor
extraction system at the central GSA dry well area to reduce VOC concentrations in soil vapor to
levels protective of ground water and to mitigate VOC inhalation risk inside Building 875.
Modeling indicates that soil vapor extraction would reduce soil vapor VOC concentrations to the
remediation goals within 10 years. The ground water remediation components of Alternatives
3a and 3b are discussed further below.
2.7.3.1 Alternative 3a—Source Mass Removal, Restoration of the Regional
Aquifer and Ground Water Plume Control
Under Alternative 3a, DOE would expand the existing ground water extraction and treatment
system in the central GSA dry well area to prevent migration of VOCs above MCLs into the
regional aquifer. In addition, ground water in the eastern GSA debris burial trenches area and
the debris burial trench area west of the sewage treatment pond would be extracted and treated to
reduce VOC concentrations to MCLs in the alluvial and regional aquifers.
Modeling indicates that TCE concentrations in the shallow aquifer in the central GSA dry
well area need to be reduced to 100 u^g/L to prevent migration of VOCs above MCLs into the
regional aquifer. After the 100 u,g/L remediation goal is achieved, ground water extraction
would be discontinued and natural attenuation would reduce VOC concentrations in the shallow
water bearing zone (Qt-Tnsc \ hydrogeologic unit) to MCLs.
The existing ground water extraction and treatment system in the eastern GSA debris burial
trenches area would continue to operate to reduce VOC concentrations in ground water to MCLs
in the shallow and regional aquifers.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
Modeling indicates that ground water extraction would reduce ground water VOC
concentrations in Building 875 and debris burial trenches areas to MCLs within 30 years and
10 years, respectively. Modeling also indicates that an additional 35 years may be required to
reduce VOC concentrations to MCLs in the shallow aquifer in the central GSA through natural
attenuation and dispersion. The configuration and operation of both the central and eastern GSA
treatment systems would be optimized during remediation to maximize system efficiency.
Ground water monitoring would be conducted throughout this 65-year period to achieve MCLs.
in both the shallow and regional aquifer plus five years of post-remediation monitoring.
The estimated 70-year present-worth cost of Alternative 3a is $17.17 million.
2.7.3.2 Alternative 3b—Source Mass Removal, Restoration of the Shallow
and Regional Aquifer and Ground Water Plume Control
Alternative 3b consists of all components of Alternative 3a but continues active ground water
extraction and treatment in the central GSA dry well area until MCLs are reached in all affected
ground water. Modeling indicates that ground water extraction in the central GSA dry well area
would reduce VOC concentrations to current MCLs in 55 years. Ground water monitoring will
be conducted throughout the 55 years of remediation, plus five years of post-remediation
monitoring.
The estimated 60-year present-worth cost of Alternative 3b is $18.90 million. This estimated
cost for Alternative 3b is slightly lower than the estimated cost presented in the GSA FS
($19.75 million) for reasons already discussed in the introduction to Section 2.7.
2.8. Summary of Comparative Analysis of Alternatives
The characteristics of the three alternatives were evaluated against the nine EPA evaluation
criteria:
• Overall protection of human health and environment.
• Compliance with ARARs.
• Short-term effectiveness.
• Long-term effectiveness and permanence.
• Reduction of contaminant toxicity, mobility, or volume.
• Implementability.
• Cost effectiveness.
• State acceptance.
• Community acceptance.
As specified by EPA, the two most important criteria are adequate protection of public health
and the environment and compliance with all Federal and State ARARs. In the following
sections and Table 8, Alternatives 1 through 3 are compared against these nine criteria.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Additional details of the evaluation of these remedial alternatives with respect to the EPA
evaluation criteria can be found in Chapter 5 of the GSA FS (Rueth and Berry, 1995).
2.8.1. Overall Protection of Human Health and the Environment
• Alternative 1 does not actively remediate contaminated soil or ground water and thus
would not protect human health or the environment because the potential beneficial uses
of ground water would not be readily restored and the potential risk associated with the
inhalation of VOCs above health-based concentrations in Building 875 are not mitigated.
• Alternative 2 protects human health by preventing ingestion of ground water containing
VOCs above MCLs. However, because VOCs are not actively remediated, potential
beneficial uses of ground water would not be readily restored. As with Alternative 1, this
alternative does not prevent potential inhalation of VOCs above health-based
concentrations in Building 875.
• Alternative 3a uses exposure control methods and administrative controls to provide
initial protection to human health. This alternative would also protect human health by
restoring and protecting the beneficial uses of ground water in the Tnbsi regional aquifer
through active remediation. Alternative 3a protects human health by preventing potential
inhalation of VOCs above health-based concentrations in Building 875 by reducing soil
vapor VOC concentrations through soil vapor extraction. Alternative 3a would employ
ecological surveys and appropriate response actions, if necessary, to protect the
environment.
• Alternative 3b uses exposure control methods and administrative controls to provide
initial protection to human health. This alternative also protects human health by
restoring and protecting the beneficial uses of ground water in both the shallow and
Tnbsj regional aquifer through active remediation. Alternative 3b protects human health
by preventing potential inhalation of VOCs above health-based concentrations in
Building 875 by reducing soil vapor VOC concentrations through soil vapor extraction.
Alternative 3b employs ecological surveys and appropriate response actions, if necessary,
to protect the environment.
2.8.2. Compliance with ARARs
A complete discussion of potential ARARs related to the three proposed remedial
alternatives is presented in the GSA FS, and summarized in Section 2.10 of this report.
• Alternative 1 meets all ARARs if natural attenuation and dispersion reduce VOC
concentrations in ground water to MCLs. If natural attenuation and dispersion do not
occur, VOC concentration would remain well above MCLs, which would not meet the
requirements of the following ARARs: Safe Drinking Water Act, the Region V Basin
Plan, or State Resolutions 68-16 and 92-49.
• Like Alternative 1, Alternative 2 would rely solely on natural attenuation to meet
remediation goals, and therefore may not comply with the requirements of the Safe
Drinking Water Act, the Region V Basin Plan, and State Resolutions 68-16 and 92-49.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January? 7997
• The goal of Alternative 3a is to use active soil vapor and ground water remediation to
meet the requirements of the Safe Drinking Water Act, the Region V Basin Plan, and
State Resolutions 68-16 and 92-49 in the Tnbsi regional aquifer. This alternative relies,
in part, on natural attenuation and dispersion, and therefore may not meet these ARARs
in the alluvial aquifer in the central GSA.
• Alternative 3b would use active soil vapor and ground water remediation to meet all
ARARs in both the alluvial and Tnbsj regional aquifer.
2.8.3. Short-Term Effectiveness
• Alternative 1 would not remove VOCs from the subsurface. Therefore, this alternative
would not be effective in short-term remediation of the site.
• Alternative 2, while preventing human exposure through ingestion of VOCs in ground
water from existing water-supply wells, does not address risk to human health from
potential exposure to VOC vapors inside Building 875. Because this alternative does not
actively reduce VOC mass, it would not provide short-term remediation of the site.
• Alternative 3a would immediately protect the public from potential exposure pathways.
This alternative uses ground water and soil vapor extraction to immediately begin
removing VOCs and reducing VOC concentrations in ground water and soil vapor, and
would be effective in the short term.
• Like Alternative 3a, Alternative 3b immediately protects the public from potential
exposure pathways. This alternative uses ground water and soil vapor extraction to
immediately begin removing VOCs and reducing VOC concentrations in ground water
and soil vapor.
• All alternatives would be effective in the short term by protecting site workers and the
community during the remedial action by preventing potential exposure through the use
of administrative controls. No adverse environmental impacts are anticipated.
2.8.4. Long-Term Effectiveness and Permanence
• Alternative 1 would not use active measures to reduce VOCs in ground water. It does not
address potential risk from ingestion of VOCs in ground water from existing water
supply wells or potential inhalation risk inside Building 875. Therefore, this alternative
would not be effective in long-term remediation of the site.
• Alternative 2 would provide protection from exposure risk at existing water-supply wells
by providing immediate and long-term response if VOCs greater than MCLs reach these
wells. However, since this alternative does not reduce VOC mass or address potential
inhalation risk inside Building 875, it would not be an effective long-term remedy.
• Alternative 3a would use ground water and soil vapor extraction to permanently reduce
VOC concentrations to MCLs in the Tnbsj regional aquifer. However, this alternative
relies on natural attenuation to reduce VOC concentrations to MCLs in the alluvial
aquifer in the central GSA. Because the reliability of natural attenuation to reach MCLs
is uncertain, this alternative may not provide an effective long-term remedy. Alternative
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3a would permanently reduce VOC soil vapor concentrations to levels protective of
ground water and mitigate inhalation risk inside Building 875.
• Alternative 3b would provide an effective long-term remedy by permanently reducing
VOCs to MCLs in both the alluvial and Tnbsi regional aquifer through active
remediation. Alternative 3b will permanently reduce VOC soil vapor concentrations to
levels protective of ground water and mitigate inhalation risk inside Building 875.
2.8.5. Reduction of Contaminant Toxicity, Mobility, or Volume
• Alternatives 1 and 2 do not actively remove VOCs from the subsurface. These
alternatives are dependent on natural attenuation processes that may not be effective in
reducing toxicity, mobility, or volume of the VOCs.
• Soil vapor and ground water extraction in Alternative 3a would significantly reduce the
toxicity, mobility, and volume of contaminants in the subsurface through active
remediation measures.
• Alternative 3b will significantly reduce the toxicity, mobility, and volume of
contaminants in the subsurface through active ground water and soil vapor remediation.
2.8.6. Implementability
• Alternative 1 could be easily implemented by utilizing the existing ground water
monitoring program.
• Alternative 2 could be implemented using the existing ground water monitoring program
and readily available services and materials for POU treatment system construction and
operation.
• Alternative 3a could be easily implemented utilizing soil vapor and ground water
extraction and treatment systems which are currently in place, permitted, and operating in
the GSA. Modifications to these systems proposed in Alternative 3a are readily
implementable.
• Alternative 3b could be easily implemented utilizing soil vapor and ground water
extraction and treatment systems which are currently in place, permitted, and operating in
the GSA. Modifications to these systems proposed in Alternative 3b are readily
implementable.
2.8.7. Cost Effectiveness
The cost estimates prepared for the remedial alternatives, as well as the assumptions made in
preparing these estimates, are described in detail in Appendix F of the GSA FS. The cost
estimates may change as the result of modifications during the remedial design and construction
process. Any revisions to the cost estimates will be presented in the Remedial Design
Document.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
• The estimated present-worth cost of Alternative 1 is $3.47 million for up to 80 years of
ground water monitoring. This alternative has the lowest cost because it does not include
active remedial actions.
• The estimated present-worth cost of Alternative 2 is $3.69 million. This includes up to
80 years of ground water monitoring and contingency POU treatment at existing water
supply wells, if necessary. Alternative 2 has a higher cost because it includes capital
construction projects (construction and installation of POU treatment systems) and
ground water monitoring, but no active remediation by long-term extraction and
treatment.
• The estimated present-worth cost of Alternative 3a is $17.17 million. This includes up to
10 years of SVE, ground water extraction for up to 10 years in the eastern GSA and 30
years in the central GSA, and up to 70 years of ground water monitoring. The higher cost
of Alternative 3a is due to capital- construction projects, extraction and treatment system
modifications, installation of additional extraction wells and piezometers, as well as long-
term extraction and treatment system operation and maintenance and ground water
monitoring. The costs incurred to implement Alternative 3a are associated with the
active remediation of soil and ground water in the GSA. Remediation would continue
until VOC concentrations in ground water are reduced to MCLs in: 1) the Tnbsj regional
aquifer in the central GSA, and 2) the alluvial aquifer and the Tnbsi regional aquifer in
the eastern GSA. Also, VOC concentrations in soil vapor will be reduced to levels
protective of ground water and to mitigate inhalation risk inside Building 875.
• The estimated present-worth cost of Alternative 3b is $18.90 million. This includes up to
10 years of SVE, ground water extraction for up to 10 years in the eastern GSA and 55
years in the central GSA, and up to 60 years of ground water monitoring. This alternative
has the highest present-worth cost because it includes all the costs of Alternative 3a but
operates the central GSA ground water extraction system for an additional 25 years. As
with Alternative 3a, the costs incurred to implement Alternative 3b are associated with
the active remediation of soil and ground water in the GSA. However, the cost of
Alternative 3b is higher due to the continued remediation of ground water to reduce VOC
concentrations to MCLs in both the alluvial and Tnbs, regional aquifers. The cost
difference between Alternative 3a and 3b represents the additional cost of remediating
ground water in the Qt-Tnsci aquifer in the central GSA to reduce VOC concentrations to
MCLs.
2.8.8. State Acceptance
The State regulatory agencies, DTSC, and CVRWQCB have provided ARARs for the site,
reviewed and evaluated the remedial technologies and alternatives, participated in the selection
of the final remedy, and provided oversight and enforcement of State environmental regulations.
The DTSC and the CVRWQCB concur with the U.S. EPA and DOE that Alternative 3b provides
the best balance of trade-offs with respect to the evaluation criteria.
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UCRL-AR-J 24061 Final ROD for the GSA Operable Unit, Site 300 January 1997
2.8.9. Community Acceptance
The regulatory agencies have monitored and reviewed public acceptance of the final selected
remedy. Public comments concerning each alternative and the selected remedy have been
considered and used, as appropriate, in the preparation of this ROD. All public comments on the
Proposed Plan, and selected remedy for the GSA are addressed in the Responsiveness Summary
section of this document.
2.9. Selected Remedy
DOE, U.S. EPA, CVRWQCB, and DISC agree that Alternative 3b is the most appropriate
remedial alternative, considering the CERCLA evaluation criteria. Under Alternative 3b, DOE
will continue subsurface remediation using ground water extraction coupled with SVE to reduce
potential risk and contaminant mass. Throughout the remediation process, other more innovative
remediation technologies will be considered to enhance VOC mass removal and treatment of
extracted soil vapor and/or ground water. In situ innovative technologies for VOC remediation
will also be considered.
This discussion of the selected remedy includes cleanup goals for the media of concern,
details of the remedy components, extraction and treatment system design and operation,
performance evaluations, consideration of innovative technologies, reporting, and a summary of
preliminary cost estimates.
2.9.1. Cleanup Goals
The objectives of the selected remedial alternative are to: 1) reduce VOC concentrations in
ground water to levels protective of human health and the environment, 2) reduce VOC
concentrations in soil vapor to meet ground water cleanup goals, and 3) mitigate VOC inhalation
risk inside Building 875.
Objectives 1 and 2 will be accomplished by ground water extraction and treatment to reduce
VOC concentrations to MCLs, supplemented with soil vapor extraction and treatment to reduce
soil vapor concentrations to meet ground water cleanup goals. Objective 3 will be accomplished
with the existing SVE system used to accomplish objectives 1 and 2. Soil vapor concentrations
protective of ground water are significantly lower than concentrations required to reduce
inhalation risk inside Building 875.
2.9.1.1. Ground Water Cleanup Goals
The cleanup goal for ground water is to reduce VOC concentrations to MCLs in all impacted
ground water in the GSA. The current MCLs for the VOC contaminants of concern in ground
water in the GSA are presented in Table 9. Ground water monitoring will be conducted as
discussed in Sections 2.9.2.1 and 2.9.3.1 to determine when MCLs for the contaminants of
concern have been achieved in ground water.
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2.9.1.2. Soil Vapor Cleanup Goals
Protection of Ground Water
One objective of SVE at the Building 875 dry well pad is to reduce VOC mass and
concentrations to meet ground water cleanup goals. The VOCs in the vadose zone will be
remediated to the extent technically and economically feasible to minimize further degradation
of the ground water by the contaminants in the vadose zone. It is generally preferable from a
technical and cost perspective to cleanup contamination in the vadose zone before it reaches the
ground water. The vadose zone cleanup will be achieved when it is demonstrated that:
1) The remaining vadose zone VOC contaminants no longer cause concentrations in the
leachate to exceed the aquifer cleanup levels, based on an interpretation of soil vapor data
using an appropriate vadose zone model. Leachate is the mobile portion of water in the
vadose zone containing soluble constituents that has been leached from the soil in the
vadose zone. Aquifer cleanup levels have been established as MCLs as defined in
applicable Federal and State safe drinking water standards; and
2) VOCs have been removed to the extent technically and economically feasible in order to
meet the aquifer cleanup levels sooner, more cost-effectively, and more reliably.
The SVE system will be operated until the demonstration is made that Items 1 and 2 above
have been met, unless the parties consent to the use of an alternate technology for the purpose of
meeting the requirements outlined in Items 1 and 2 above. DOE, U.S. EPA, DTSC, and the
CVRWQCB agree to evaluate the performance of the SVE system, as well as to determine when
vadose zone cleanup has been achieved based on the technical criteria discussed in
Section 2.9.3.2.
Risk Reduction within Building 875
The SWRI baseline risk assessment indicated that the cumulative potential excess cancer risk
from inhalation of indoor air within Building 875 was 10~5. This calculation was based on VOC
concentrations from soil samples collected in the vicinity of the Building 875 dry well pad prior
to the July 1994 startup of the SVE system. It is likely, due to nearly two years of ongoing SVE
soil remediation, that current VOC soil concentrations are lower than what was used to calculate
this excess cancer risk in the baseline risk assessment. Soil vapor concentrations protective of
ground water are significantly lower than concentrations that will be required to reduce potential
inhalation risk inside Building 875. DOE will conduct soil vapor monitoring, as discussed in
Section 2.9.3.2, and use these data to validate reduction of potential inhalation risk inside
Building 875.
2.9.2. Treatment System Design
The majority of the remediation components are readily implementable with minor
modifications to the existing soil vapor and ground water extraction and treatment systems at the
GSA OU.
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The major components of the selected remedy (Alternative 3b) include:
• Ground water monitoring throughout the predicted 55 years of remediation plus
five years of post-remediation monitoring.
• Administrative controls including access restrictions and procedures for construction in
areas where possible exposure to contaminated media may occur.
• Contingency POU treatment for offsite water-supply wells.
• Soil vapor extraction and treatment in the central GSA dry well source area.
• Extraction and treatment of ground water in the central and eastern GSA.
The design, operational, and/or implementation details of these components are discussed in
detail in the following sections.
2.9.2.1. Monitoring and Administrative Controls
Monitoring
Currently, the preliminary ground water monitoring program for the selected remedy
(Alternative 3b) consists of sampling 7 wells quarterly, 89 wells semiannually, and 12 wells
annually for the first 10 years. Between years 11 and 55, after the eastern GSA ground water
extraction system and two of the central GSA extraction wells have been turned off, sampling
frequency will be reduced to semiannually for 39 wells, and annually for 50 wells. After 55
years, when ground water fate and transport modeling predicts that VOC concentrations in
ground water have been reduced to MCLs and the central GSA ground water extraction system
can be turned off, ground water sampling will be reduced further to semiannually for 37 wells
and annually for 37 wells for the five years of post-remediation monitoring. Samples will be
analyzed for VOCs by EPA Method 601, and some wells in the central GSA would also be
analyzed for fuel hydrocarbons by EPA Method 602. If remediation does not show that cleanup
is proceeding as the modeling predicts, remediation methods will be revisited.
Consistent with the NCP, the ground water data obtained as part of the monitoring program
will be reviewed at least every five years. If these data indicate that VOC concentrations, ground
water flow direction, and/or velocity have changed and significantly affect the cleanup, the
monitoring program would be re-evaluated.
Soil vapor concentrations will be monitored periodically from the seven extraction wells
during the predicted 10 years of SVE to evaluate remediation progress and provide data for
system optimization. VOC concentrations in soil vapor samples can be used to determine if
there is preferential VOC removal from certain SVE wells. This information will be used to vary
the extraction configuration to optimize VOC mass removal from soil vapor; i.e., extract from
wells with higher VOC soil vapor concentrations while using wells with lower VOC
concentrations as air inlet wells. The configuration and operation of the SVE system will be
optimized during remediation to maximize system efficiency.
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In addition, existing soil vapor monitoring points in the vicinity of Building 875 will be
monitored for TCE and PCE. The TCE and PCE concentrations will be used to periodically
evaluate the effectiveness of SVE in mitigating inhalation risk inside Building 875. .
Although the inhalation risk inside Building 875 was calculated by adding the individual
lifetime cancer risk for a total of six VOCs, the sum of the individual cancer risks for TCE and
PCE (1.11 x 10~5) constitutes the largest portion of the total additive inhalation cancer risk inside
Building 875 (1.17 x 10~5). For this reason, TCE and PCE will be used as the indicator VOCs
for periodically assessing additive inhalation cancer risk inside Building 875. Once the additive
inhalation risk reaches acceptable levels for TCE and PCE, soil vapor samples will be collected
and analyzed for all six VOCs originally used to calculate inhalation risk inside Building 875 in
the SWRI. These data will then be used as direct input parameters to the models that were used
to calculate inhalation risk in the SWRI to calculate a total additive inhalation cancer risk inside
Building 875.
Soil vapor monitoring will be discussed in detail in the remedial design document.
Specific details of the ground water and soil vapor monitoring network will be presented in
the Remedial Design document.
Additionally, surface water from springs 1, 2, and GEOCRK will be sampled and analyzed
for VOCs, drinking water metals, general minerals, high explosives, tritium, and gross alpha and
beta as part of ongoing site-wide program of ecological studies. The current program of
conducting ecological resource surveys for sensitive species prior to the initiation of any ground-
disturbing activities will also continue. The need for detailed ecological resource surveys will be
evaluated every five years as part of the contract renewal negotiations between the University of
California and DOE.
Administrative Controls
The following administrative controls are a component of the selected remedy and are either
currently in effect or easily implementable. Because DOE intends to retain stewardship of
Site 300 for the foreseeable future, existing security patrols, site access restrictions, and fencing
along the entire perimeter of Site 300 will be maintained. These restrictions will prevent public
access, and thus potential exposure, to the source areas and areas of highest ground water VOC
concentrations. Additionally, DOE will continue to consider site conditions (especially in the
vicinity of vadose zone contamination) prior to implementing construction of any facility to
prevent potential worker exposure to subsurface contaminants.
2.9.2.2. Contingency Point-of-Use Treatment
POU treatment systems will be installed at offsite water-supply wells CON-1, CDF-1 and
SR-1 (Fig. 10) if VOCs in these wells are at or above MCLs. As part of the monitoring plan,
water-supply wells CON-1 and CDF-1 will be monitored for VOCs monthly. Guard wells W-
25D-01, W-25D-02, and W-24P-03, located the farthest downgradient from the source and
upgradient from water-supply well SR-1, will also be monitored for VOCs. Well W-24P-03 will
be monitored quarterly, and wells W-25D-01 and -02 monitored semiannual. If VOCs are
detected in well W-24P-03, the monitoring frequency of this well will be increased to monthly,
and wells W-25D-01 and -02 monitored quarterly. Should VOCs be detected in well W-24P-03,
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provisions will be made to routinely sample well SR-1. In the event that VOCs at or above
MCLs are detected and confirmed in wells CDF-1, CON-1, or SR-1, implementation of POU
treatment at that well will be discussed with the regulatory agencies and well owner(s).
Wells CDF-1 and CON-1 are located approximately 100 and 200 ft, respectively, from the
Site 300 GSA boundary. Due to the close proximity of these wells to the VOC plume, DOE
currently has a POU contingency plan in place for these wells in a Memorandum of
Understanding that has been reviewed and approved by the well owner.
Well SR-1 is located approximately 1.5 miles downgradient from guard well W-24P-03. No
VOCs have ever been detected in ground water collected from W-24P-03, the furthest
downgradient well. In addition, the VOC plume has been receding upgradient back toward Site
300 as result of remediation efforts and is currently over 2 miles from well SR-1. However, if
VOCs were detected in guard well W-24P-03, the property owner would be contacted to set up a
contingency plan similar to that established for wells CON-1 and CDF-1.
The conceptual POU treatment system design consists of a gravity-flow aqueous-phase GAC
treatment system utilizing two GAC canisters connected in series and mounted on a double-
containment skid. Sampling ports will be provided between the canisters, as well as at the inlet
and exit pipes. Other equivalent treatment technologies may be considered, if appropriate.
In the event that POU treatment becomes necessary, DOE will develop and submit a plan for
regulatory approval to permanently remedy the affected water supply.
2.9.2.3. Soil Vapor Extraction and Treatment
SVE will be used as the primary remedial technology to: 1) reduce vadose zone
contamination, including potential DNAPLs in unsaturated bedrock, to concentrations protective
of ground water, and 2) reduce potential inhalation risk inside Building 875. Most vadose zone
contamination is found in the immediate vicinity of the Building 875 dry well pad, so SVE
efforts will be focused in that area.
Residual DNAPLs may be in the vadose zone and dewatered bedrock in the vicinity of the
Building 875 dry well pad. The dewatered zone consists of bedrock that was formerly saturated
prior to the initiation of ground water extraction activities in the central GSA, but is now
unsaturated or dry due to pumping. SVE and treatment would also address residual DNAPLs.
SVE has been identified as a technology that can effectively remediate volatile DNAPLs in the
unsaturated zone and prevent uncontrolled migration of VOCs in soil gas (U.S. EPA, 1992d;
1993b). In addition, when SVE is coupled with lowering of the water table through ground
water extraction, residual DNAPLs can be removed from the area below the original water table
elevation (U.S. EPA, 1992d).
In July 1994, soil vapor extraction and treatment activities were initiated in the central GSA
Building 875 dry well pad area. The current SVE system uses seven extraction wells and treats
the vapor with two 140-lb vapor-phase GAC canisters connected in series prior to discharge to
the atmosphere. The locations of the SVE wells are shown in Figure 11. VOC concentrations in
the SVE-combined influent stream have decreased from a high of 450 ppmv/v in July 1994 to
current concentrations of 5 ppmv/v or below in the second quarter 1996. Similarly, VOC
concentrations in soil vapor samples from the individual SVE wells have decreased from a
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maximum concentration of 600 ppmv/v in well W-7I at system startup to a maximum of 33
ppmv/v in well W-875-07 in the second quarter 1996. As of second quarter 1996, 27,238 grams
of VOCs have been removed in the central GSA through SVE.
Soil vapor is currently extracted at rate of approximately 20 standard cubic ft per minute.
Based on field observations, we estimate that the current system adequately captures the soil
vapor plume in the Building 875 dry well pad source area and that no additional SVE wells are
necessary. The necessity of performing SVE at other locations in the GSA OU will be evaluated
as remediation progresses. Other equivalent soil vapor treatment technologies may be
considered, if appropriate.
The seven SVE wells are also used for ground water extraction and are successfully
maintaining a dewatered zone in the immediate vicinity of the Building 875 dry well pad.
Dewatering has exposed more soil/rock to the applied vacuum of SVE, thereby significantly
enhancing VOC mass removal. This dewatered zone will continue to be maintained while SVE
is operating.
The central GSA treatment is a dual soil vapor and ground water extraction and treatment
system, and both systems will initially be operated simultaneously. Upon reaching conditions
presented in Section 2.9.3.2, the soil vapor system will be shut down and only the ground water
extraction and treatment system will operate. Should site conditions change or ground water
monitoring indicate that soil vapor concentrations have rebounded and will cause ground water
to exceed ground water cleanup goals, the soil vapor system will be restarted and operated as
appropriate until such conditions cease. DOE agrees to operate the dual soil vapor and ground
water extraction and treatment system to reduce ground water VOC concentrations to meet
ground water cleanup goals in the most efficient manner.
During preparation of the remedial design report and throughout the life of the project, DOE
may conduct more extensive testing to determine the effective vacuum influence and to optimize
performance. Optimization may include expanding the SVE system with additional existing
wells to increase the area of influence, and/or implementing cyclic operation (e.g., alternating
periods when the system is on and off) to maximize the rate of VOC mass removal.
2.9.2.4. Ground Water Extraction and Treatment
Eastern GSA
As shown in Figure 8, ground water concentrations exceed MCLs in the eastern GSA in the
vicinity of the former debris burial trench area, east of the sewage treatment pond. Ground water
extraction and treatment in this area is designed to reduce ground water VOC concentrations to
MCLs.
The eastern GSA ground water extraction system has been operating since July 1991, and
currently consists of three extraction wells pumping a total of up to 46 gal per minute (gpm). As
of second quarter 1996, over 76 million gal of ground water have been extracted and treated in
the eastern GSA ground water treatment system with 4,417 grams of VOCs removed from
ground water.
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UCRL-A.R-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Data collected through fourth quarter 1995 indicate that TCE concentrations have been
generally decreasing in all eastern GSA alluvial wells since 1992. There was an average TCE
concentration decrease of 75% in eastern GSA alluvia] wells between the historical maximum
concentration and the concentration in third quarter 1994. The maximum observed TCE
concentration in eastern GSA alluvial wells in fourth quarter 1995 was 18 \ig/L in well
W-26R-01, a significant decrease from the historical maximum concentration of 74 jag/L TCE in
well W-26R-03 in January 1992.
The 1 p.g/L isoconcentration contour for the ground water VOC plume in the eastern GSA
previously extended 4,750 ft downgradient from the debris trench area and the 5 Jig/L
isoconcentration contour extended 4,625 ft downgradient based on fourth quarter 1991 (SWRI)
data (Fig. 12). Fourth quarter 1995 data indicate that the 1 \ig/L isoconcentration contour for the
ground water VOC plume now extends only 1,950 ft downgradient from the debris burial trench
area, while the 5 Jig/L isoconcentration contour extends only 600 ft downgradient (Fig. 8).
Remediation efforts in the eastern GSA are thought to be at least partially attributable to this
decrease in plume length.
VOC concentrations in the regional aquifer in the eastern GSA have also been significantly
decreasing as a result of existing alluvial ground water remediation. TCE concentrations have
decreased in ground water in the Tnbsi regional aquifer from a maximum of 71 Hg/L in third
quarter 1992, to a maximum of 19.2 jig/L in fourth quarter 1995 as shown in Figures 13 and 9,
respectively. In this area, the alluvium and underlying regional aquifer are hydraulically
connected, and contamination in the regional aquifer is a result of downward vertical migration
of contaminants from the alluvial aquifer. An extraction well in the regional aquifer in the debris
burial trench area was not considered due to concerns that pumping the regional aquifer would
accelerate/facilitate downward vertical contaminant migration from the overlying source in the
alluvium into the Tnbsi. If remediation of the alluvial aquifer does not appear effective in
removing VOCs from ground water in the regional aquifer in the future, direct remediation of the
regional aquifer in the eastern GSA will be considered.
Based on modeling and field data associated with the existing extraction system, the
extraction well configuration shown in Figure 11 sufficiently captures the plume in the eastern
GSA to meet remediation goals. The portion of the plume downgradient of the eastern GSA
extraction wells that is not being actively captured has been retreating since ground water
extraction was initiated. We anticipate this trend will continue. Therefore, no additional wells
are necessary at this time. The effectiveness of this system is discussed in Section 1.4.8.2 of the
GSA FS.
Ground water modeling predicts that the eastern GSA ground water extraction and treatment
system will remediate ground water to MCLs in five years. However, we have conservatively
assumed that this system will need to operate for ten years.
In the GSA FS, a low-profile shallow-tray air stripper was the chosen treatment system for
ground water in the eastern GSA. Aqueous-phase GAC was not a selected technology in the FS
due to concerns regarding possible biofouling and clogging that might require premature GAC
replacement, and thereby reduce system efficiency. The FS also stated that aqueous-phase GAC
treatment was being further evaluated as a component of the final system design. Since issuing
the GSA FS in October 1995, aqueous-phase GAC was evaluated for ground water treatment in
the eastern GSA. This evaluation consisted of:
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VCRL-AR-124061 » Final ROD for the GSA Operable Unit, Site 300 January 1997
1. Reviewing ground water chemistry data from eastern GSA extraction wells to evaluate
the potential for carbonate clogging or bacterial biofouling of the GAC system.
2. Performing a system test by connecting two aqueous-phase GAC units to the eastern
GSA treatment system to monitor the effectiveness of GAC in reducing VOCs, and to
identify potential problems such as biofouling and clogging.
Two aqueous-phase GAC units were connected in series prior to the air sparging tank. Water
from the eastern GSA extraction wells passed through sediment filters and then went directly
into the GAC units. The GAC units were sampled and monitored to ensure VOCs were
effectively removed to the NPDES permit required levels, and to evaluate the potential effects of
biofouling and carbonate clogging on GAC system efficiency. Following treatment in the GAC
units, the water passed through the air sparging tank. The GAC units were evaluated in this
manner for eight months, from December 1995 to August 1996. The results of this evaluation
indicated that: 1) the aqueous-phase GAG units effectively removed VOCs from ground water to
NPDES permit levels (<0.5 Hg/L), and 2) there is no evidence of system efficiency reduction or
premature replacement of GAC due to biofouling and clogging of the GAC units.
As discussed in Section 3.3.5.1.1 of the GSA FS, aqueous-phase GAC adsorption is a well
established and effective technology for treating chlorinated solvents in ground water. Activated
carbon removes contaminants from water by adsorbing them onto its surface. A GAC adsorption
system consists of a packed column with an internal plumbing system to distribute the water
evenly through the carbon bed. Organic compounds adsorb onto the surface of the GAC as the
water flows through the fixed bed.
Aqueous-phase GAC treatment is generally considered to be most effective for low-flow and
low-concentration applications. Influent TCE concentrations to the eastern GSA treatment
system have steadily declined from a high of 63 H-g/L in September of 1991 to an average of 8.2
\igfL for the last four quarters (3rd quarter 1995 to 2nd quarter 1996) and continue to decline.
The GAC technology was demonstrated to be effective in treating the eastern GSA ground water
at these low concentrations.
Aqueous-phase GAC adsorption is a one-step treatment process as opposed to two-step
treatment necessary with air stripping where VOCs are removed from water and are then driven
into the vapor phase. Following air stripping, the VOC-laden vapors are treated in vapor-phase
GAC units. The aqueous-phase GAC technology, which is inherently less complex in both
design and operation than air stripping technology, will incur lower operation and maintenance
costs over the long term.
The aqueous-phase GAC technology was evaluated in the eastern GSA and was determined
to be:
1. Effective in removing VOCs from ground water to NPDES permit levels (<0.5 p.g/L),
2. Capable of treating water to meet all other NPDES permit discharge limits; i.e., pH and
total dissolved solids, and
3. More cost effective for long-term operation and maintenance.
As a result, aqueous-phase GAC has replaced air stripping as the preferred technology for the
treatment of ground water in the eastern GSA.
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Extracted ground water will continue to be treated by two to three aqueous-phase GAC units
connected in series (Fig. 14). Other equivalent ground water treatment technologies may be
considered in the future, if appropriate. The system has a treatment flow rate capacity of
50 gpm. Ground water is treated to reduce VOC concentrations to the National Pollutant
Discharge Elimination System (NPDES) permit requirements of 0.5 fig/L total VOCs. Treated
water will continue to be discharged by gravity flow to Corral Hollow Creek about 750 ft to the
south. Discharged treated water will continue to be monitored to ensure compliance with
NPDES permit requirements issued by the CVRWQCB.
A portion of the treated water from the eastern GSA treatment facility may occasionally be
discharged to sewage treatment pond to the west as makeup water. During the hot, dry summer
months, approximately 1,000 to 1,500 gal of makeup water is added to the sewage treatment
pond to compensate for evaporation, which is necessary to keep the sewage treatment pond
operating efficiently. It is currently being proposed that treated water from either the eastern or
central GSA treatment facilities be used as this makeup water. In the event that treated water
from the eastern GSA treatment facility is diverted to the sewage treatment pond as makeup
water, this will have little overall impact on ground water or Corral Hollow Creek as this
treatment facility typically discharges over 40,000 gal a month. Due to the low volume of
makeup water required by the sewage treatment pond, and the limited time frame when makeup
water is required (summer months only), the majority of the treated water from the eastern GSA
treatment facility would continue to be discharged to Corral Hollow Creek, providing recharge to
the underlying aquifer.
Central GSA
As shown in Figure 6, most VOCs in the GSA OU subsurface are in the central GSA,
primarily in the vicinity of the Building 875 dry well pad. While VOC concentrations in ground
water are above MCLs in the Tnbs i regional aquifer west of the sewage treatment pond (Fig. 7),
the highest ground water VOC concentrations are in the upgradient overlying alluvial aquifer
(Fig. 6) at the Building 875 dry well pad. Ground water extraction and treatment in this area is
designed to reduce ground water VOC concentrations to MCLs in both the alluvial and Tnbsi
regional aquifer.
Since April 1993, a ground water treatment system has been in operation in the central GSA
at the former Building 875 dry well pad area as part of a CERCLA Removal Action. Currently,
the central GSA ground water extraction system pumps a total of approximately 0.3 gpm from
seven extraction wells located in the vicinity of the Building 875 dry well pad (Fig. 11). This
very low flow rate is a result of the successful dewatering of the area. As of second quarter
1996, over 568,000 gal of ground water have been extracted and treated in the central GSA
ground water treatment system and 3,932 grams of VOCs removed from ground water. A
comparison of VOC ground water data collected from Qt-Tnscj wells during the third quarter
1994 to the historical maximum observed concentrations indicates an overall decrease in VOC
concentrations. Specifically, the maximum observed TCE concentration for all Qt-Tnscj wells
in samples collected in the third quarter of 1994 was 10,000 JJ.g/L, representing a decrease from
the historical maximum observed concentration of 240,000 u\g/L in a bailed ground water sample
collected from well W-875-07 in March 1992(Fig. 15). Third quarter 1994 analytical data
suggest that ground water samples collected from the Building 875 dry well pad wells do not
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
contain TCE at concentration indicative of the presence of DNAPLs in the saturated zone.
However, the residual DNAPLs may be present in soil in the dewatered zone and/or vadose
zone. The drop in TCE concentrations is thought to be attributable to ground water and soil
vapor extraction and treatment efforts ongoing in the central GSA. We have been unable to
collect ground water samples from the dry well pad wells since third quarter 1994 because these
wells have been effectively dried out preventing ground water sample collection.
Historically, TCE has been detected in ground water samples from monitor wells located
west of the sewage treatment pond, which are completed in the Tnbsi regional aquifer (Fig. 16).
Data indicates that VOC contaminants are in the regional aquifer in the central GSA only where
the regional aquifer directly underlies contaminated portions of the alluvial aquifer, such as the
area immediately west of the sewage treatment pond. Where present, the Tnscj confining layer
acts as a competent confining layer in the vicinity of Building 875 and the areas to the west,
preventing TCE migration from the shallow Qt-Tnscj aquifer into the underlying Tnbsj regional
aquifer.
Data indicate that TCE concentrations have generally been decreasing in all Tnbsi monitor
wells in the central GSA since 1990. The measured decrease in TCE concentrations may be
attributable to the sealing and abandonment of wells 7 and 19 (Fig. 16) in 1988 and 1989. Prior
to sealing and abandonment, these wells pumped up to 200 gpm and may have reversed the
natural hydraulic gradient, thus causing TCE to migrate into the Tnbsj from the overlying
alluvium. When pumping ceased from wells 7 and 19, the pre-pumping hydraulic gradient
appears to have been re-established in the Tnbsi and, as a result, the TCE concentration in the
bedrock aquifer have decreased.
In addition to the seven existing ground water extraction wells, six existing monitor wells
(W-7F, W-7O, W-872-02, W-7P, W-873-06, and W-873-07) will be converted to ground water
extraction wells. Additionally, one new ground water extraction well, W-7Q, will be installed.
The purposes of these new ground water extraction wells are to maximize contaminant mass
removal in source areas and prevent plume migration in both the alluvial and Tnbsi regional
aquifer. Extraction from these new ground water extraction wells will increase the total central
GSA flow rate from the current 0.3 gpm to approximately 15 gpm.
Ground water monitor well W-7P will be converted to an extraction well to reduce VOC
concentrations in the Tnbs i regional aquifer west of the sewage treatment pond. However,
extraction from this well may not be initiated until alluvial aquifers extraction stabilizes capture
zones and further reduces contamination in the alluvial aquifer.
In conjunction with source area ground water extraction described above, ground water will
be extracted from three new extraction wells (W-7R, W-7S, and W-7T) to be installed in the
alluvial aquifer about 150 ft west of the sewage treatment pond (Fig. 11). These three extraction
wells will capture VOCs not captured.by the source area extraction wells, and prevent VOCs
from migrating into the Tnbsi regional aquifer. Ground water extraction from these three wells
will likely continue until ground water extraction in the source areas is discontinued.
Modeling predicts that ground water extraction in the central GSA will likely be required for
55 years to reduce VOC concentrations to current MCLs. Extraction from wells W-873-06 and
W-873-07 will be discontinued after 10 years if VOC concentrations in the alluvial aquifer in
these source areas has reached MCLs, as modeling predicts.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Ground water extracted in the central GSA will be treated using the existing treatment system
with upgrades including replacement of the existing air sparging tanks with a low-profile tray air
stripper, aqueous-phase granular activated carbon (GAC), or other equivalent technologies to
increase VOC removal efficiency and reduce electrical costs (Fig. 17).
Ground water treatment will continue to reduce VOC concentrations to meet the Substantive
Requirement of 0.5 u.g/L total VOCs. Treated water will continue to be discharged to a remote
canyon in the eastern GSA where the water rapidly infiltrates into the sandstone bedrock.
Discharged treated water will be monitored to ensure compliance with Substantive Requirements
issued by the CVRWQCB. A portion of the treated water from the central GSA treatment
facility may occasionally be discharged to the sewage treatment pond to the east as makeup
water during the summer months. In the event that treated water from the central GSA treatment
facility is diverted to the sewage treatment pond as makeup water, the overall impact on ground
water would be minimal as this treatment facility typically discharges 15,000 to 25,000 gal a
month to the canyon in the eastern GSA. Due to the low volume of makeup water required by
the sewage treatment pond, and the limited time frame when makeup water is required (summer
months only), the majority of the treated water from the central GSA treatment facility would
continue to be discharged to the eastern GSA canyon, providing recharge to the underlying
aquifer.
Once ground water extraction from Tnbsi well W-7P is initiated, treated ground water will
also be reinjected into well W-7C, screened downdip of W-7P (Fig. 11). Reinjection will
enhance natural contaminant flushing toward extraction well W-7P and expedite remediation of
the Tnbsi regional aquifer. Hydraulic testing will be performed prior to reinjection to ensure that
reinjection will not adversely affect remediation effectiveness or accelerate plume migration. In
addition to hydraulic testing and prior to reinjection, treated ground water will be analyzed to
verify removal of VOCs to discharge requirements (<0.5 jig/L total VOCs). Analyses will also
ensure that concentrations of inorganic compounds do not exceed levels found in water extracted
from the Tnbsj regional aquifer.
If air stripping is selected as the treatment technology, the vapor stream from the air stripper
will be treated by two vapor-phase GAC canisters connected in series and discharged to the
atmosphere. The treated vapor stream will be monitored to ensure compliance with the
San Joaquin Valley Unified Air Pollution Control District permit requirements. If aqueous-
phase GAC is selected as the remedial technology, no vapor stream will exist, therefore air
discharge permits will not be necessary.
The exact number and location of ground water extraction wells will be presented in
subsequent design documents. Similarly, the choice of treatment technologies will be evaluated
on an ongoing basis to implement the most cost-effective technology that meets all performance
criteria.
2.9.3. Performance Evaluations
Ground water and soil vapor monitoring will be conducted throughout the life of the GSA
OU remediation project to evaluate the performance and effectiveness of the treatment systems
in meeting remediation goals.
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
2.9.3.1. Ground Water Remediation
Ground water monitoring, as described in Section 2.9.2.1 will be conducted to evaluate the
effectiveness of ground water remediation in reducing VOC concentrations to MCLs in the
shallow aquifer and Tnbsi regional aquifer. Details of the ground water monitoring network will
be presented in the Remedial Design document.
In addition, several new piezometers will be installed for measuring water levels near the
extraction wells to help evaluate ground water capture and remediation effectiveness. Locations
of these piezometers will be determined after ground water extraction begins in order to optimize
piezometer placement, and will be discussed in the Remedial Design report.
When VOC concentrations in ground water have been reduced to cleanup goals (MCLs), the
ground water extraction and treatment system(s) will be shut off and placed on standby.
Modeling indicates that VOC concentrations in ground water in the eastern GSA should be
reduced to MCLs within 10 years following the initiation of remediation and within 55 years in
the central GSA. Ground water in the GSA will continue to be monitored for a period of five
years following shutdown of the system(s). Should VOC concentrations in ground water
"rebound" or increase above cleanup goals, reinitiation of remediation efforts will be discussed
with the regulatory agencies. If remediation does not show that cleanup is proceeding as
modeling predicts, remediation methods will be revisited.
As presented in the National Research Council report (NRC, 1994), the ability of restoring
ground water to MCLs using active pumping is unlikely at most sites. If, at some later date,
DOE, U.S. EPA, CVRWQCB, and DTSC determine that it is technically and economically
infeasible to reduce VOCs in ground water to the cleanup levels established in this ROD, after all
reasonable efforts have been made, these parties may re-evaluate the need to achieve these goals.
Throughout the remediation process, innovative remediation technologies will be considered
to enhance VOC mass removal and treatment of ground water, as discussed in Section 2.9.4.
2.9.3.2. Soil Vapor Remediation
The primary objectives of soil vapor remediation at the central GSA are to: 1) reduce vadose
zone contamination to concentrations to meet ground water cleanup goals, and 2) reduce
potential inhalation risk inside Building 875. Because the second objective will likely be
achieved long before achieving the first objective, the performance evaluation of the central GSA
SVE system will focus on ground water protection, in accordance with ARARs, State Water
Resources Control Board Resolution 92-49, and the Region V Basin Plan.
To monitor the progress of subsurface soil remediation, soil vapor concentrations will be
monitored at dedicated soil vapor sampling points and at SVE wells through the life of the SVE
remediation. In addition, DOE/LLNL will evaluate SVE remediation effectiveness by tracking
the cumulative mass of VOCs removed from the Building 875 dry well pad area. The mass of
VOCs removed from soil vapor will be plotted as a function of time to determine when the
cumulative mass removed approaches asymptotic levels.
As part of the selected remedy, VOC concentrations in soil vapor will be monitored utilizing
soil vapor sampling points to ensure that the inhalation risk inside Building 875 is adequately
managed. Should existing dedicated soil vapor monitoring points in the vicinity of Building 875
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
prove insufficient to demonstrate the effectiveness of soil vapor extraction in mitigating the
potential inhalation risk in Building 875, additional soil vapor monitoring points will be
considered.
The demonstration that the vadose zone cleanup has been achieved to the point where the
remaining vadose zone VOC contaminants no longer cause concentrations in the leachate to
exceed the aquifer cleanup levels will be made through contaminant fate and transport modeling,
trend analysis, mass balance, and/or other means. This demonstration will include examination
of the current effects of remaining vadose zone contamination on the ground water, using an
appropriate vadose zone model, if necessary. In the case that it is demonstrated that the soil
vapor concentration for TCE has reached 360 parts per billion (ppb) on a volume-to-volume
basis (and similarly derived concentrations for other VOCs) in the vadose zone, the parties agree
that the demonstration has been made that the remaining vadose zone VOC contaminants will no
longer cause concentrations in the leachate to exceed the aquifer cleanup level. If it is
demonstrated that there is no water moving through the vadose zone and no potential for leachate
to be produced at the current time or in the future, the parties agree that the demonstration that
the remaining vadose zone VOC contaminants will no longer cause concentrations in the
leachate to exceed aquifer clean-up levels has been made.
The SVE system will be operated until it is demonstrated that VOC removal from the vadose
zone is no longer technically and economically feasible in order to meet the aquifer cleanup
levels sooner, more cost effectively, and more reliably. This feasibility analysis will include
consideration of the follow factors (these factors are not dispositive and other factors may be
considered upon agreement of the parties):
1) Whether the predicted concentration of leachate from the vadose (using an appropriate
vadose zone model that interprets soil gas data) will exceed the ground water cleanup
standard;
2) Whether the predicted concentration of the leachate from the vadose zone (using an
appropriate vadose zone model that interprets soil gas data) will cause the ground water
to exceed the aquifer cleanup levels;
3) Whether the mass removal rate is approaching asymptotic levels after temporary
shutdown periods and appropriate optimization of the SVE system;
4) The additional cost of continuing to operate the SVE system at concentrations
approaching asymptotic mass levels;
5) The predicted effectiveness and cost of further enhancements to the SVE system (e.g.,
additional vapor extraction wells, air injection) beyond system optimization of the
existing system;
6) Whether the cost of ground water remediation will be significantly more if the residual
vadose zone contamination is not addressed;
7) Whether residual mass in the vadose zone will significantly prolong the time to attain the
ground water cleanup standard;
8) Historic data that present the SVE system operating costs per unit VOC mass removed
from the vadose zone and the concurrent soil vapor VOC concentrations, both as a
function of time; and
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
9) Historic data that present the ground water extraction and treatment system operating
costs per unit VOC mass removed from the ground water and the concurrent ground
water VOC concentrations, both as a function of time.
Other factors may be considered upon agreement between DOE, U.S. EPA, CVRWQCB, and
DTSC.
The SVE system may be cycled on and off in order to optimize SVE operation and/or to
evaluate the factors listed above. DOE, U.S. EPA, CVRWQCB, and DTSC will jointly make the
decision that VOC cleanup of the vadose zone has been achieved and the SVE system may be
shut off permanently.
If at some later date, DOE, U.S. EPA, CVRWQCB, and DTSC determine that it is
technically or economically infeasible to reduce VOCs in the vadose zone to levels which no
longer cause concentrations in the leachate to exceed aquifer cleanup levels, after all reasonable
efforts have been made, the parties will re-evaluate the need to achieve this goal, provided that
VOCs have been removed from the vadose zone to the extent technically and economically
feasible and to the satisfaction of the DOE, U.S. EPA, CVRWQCB, and DTSC. This situation
will require a more rigorous feasibility analysis because the incremental benefit of removing
VOCs from the vadose zone is generally much higher as long as there are VOC contaminants in
the vadose zone that cause concentrations in the leachate to exceed aquifer cleanup levels.
Aquifer cleanup goals must be met even though the goal to reduce VOCs in vadose zone to
levels that no longer cause concentrations in the leachate to exceed aquifer cleanup levels is not
achieved.
Throughout the remediation process, innovative remediation technologies will be considered
to enhance VOC mass removal and treatment of soil vapor, as discussed in Section 2.9.4.
Once the ground water has reached cleanup levels, DOE, U.S. EPA, CVRWQCB, and DTSC
agree that:
1) It is not technically and economically feasible to operate the SVE beyond the point where
the remaining vadose zone VOC contaminants no longer cause the concentrations in the
leachate to exceed the aquifer cleanup level; and
2) There is relatively little benefit in continuing SVE because aquifer cleanup levels have
been achieved and contaminants in the vadose zone will not cause contaminant
concentrations in ground water to increase.
2.9.4. Innovative Technologies
Innovative technologies that shorten cleanup time, improve cleanup efficiency, and reduce
cost will continue to be considered for application at the GSA throughout the remediation
process. These technologies may be employed at the GSA if site conditions change or
technology development and testing indicate a potential for cost-effective and expedited
remediation. Innovative technologies will be employed with regulatory agency concurrence.
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2.9.5. Reporting
Performance summaries for the ground water and soil vapor extraction and treatment systems
will be submitted to the U.S. EPA, DISC, and the CVRWQCB on a quarterly basis. A schedule
for submitting ground water and vadose zone monitoring data and contaminant plume
concentration contour maps will be included in the remedial design document.
2.9.6. Summary of Preliminary Cost Estimates
The 1995 present-worth cost of the selected remedy is estimated to be approximately
$18.90 million as detailed in Table 10. Many of the costs for technology development,
equipment purchases, and facility construction associated with the implementation of the
selected remedy presented in Table 10 have already been incurred. This cost estimate assumes
up to 10 years of SVE and monitoring, up to 10 years of ground water extraction in the eastern
GSA, up to 55 years of ground water extraction in the central GSA, and up to 60 years of ground
water monitoring. These time and cost estimates do not include the development, testing, or
implementation of innovative technologies. Cost estimates and equipment may change as the
result of modifications during the remedial design and construction processes. Cleanup goals
and cleanup time estimates can be re-evaluated with the regulatory agencies every five years,
based on the effectiveness of the remediation system, changes in site conditions, and changes in
regulatory requirements.
2.10. ARARs
CERCLA Section 121 (d)(2)(A) requires that remedial actions meet any Federal standards,
requirements, criteria, or limitations that are determined to be legally applicable or relevant and
appropriate. CERCLA Section 121 (d)(2)(A)(ii) requires that State ARARs be met if they are
more stringent than Federal requirements.
There are three general kinds of ARARs:
1. Chemical-specific requirements that define acceptable exposure concentrations or water
quality standards,
2. Location-specific requirements that may restrict remediation activities at sensitive or
hazard-prone locations such as wildlife habitat and floodplains, and
3. Action-specific requirements that may control activities and/or technologies.
A list of potential ARARs related to the three proposed remedial alternatives was presented
in the GSA FS. ARARs directly related to the selected remedy is contained in Table 11 of this
ROD. These ARARs: 1) cite the most directly pertinent requirements related to specific actions
to be taken as part of the selected remedy, and 2) provide a mechanism for enforcement of
standards directly related to the selected remedy (i.e., NPDES waste water discharge and air
discharge permits). When State ARARs are more stringent than Federal requirements, only the
State ARAR is listed in the table.
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2.10.1. Chemical-Specific ARARs
SWRCB Resolution 92-49 entitled "Policies and Procedures for Investigation and Cleanup
and Abatement of Discharges Under Water Code Section 13304" is a chemical-specific ARAR
for aquifer (ground water) remediation goals. Resolution 92-49 provides general policies on
investigation, monitoring, and reporting. All ground water cleanup activities associated with
implementation of the selected remedy for the GSA will be conducted under the supervision of
the CVRWQCB and in accordance with Resolution 92-49. In addition, Resolution 92-49
authorizes the CVRWQCB to determine cleanup goals which must consider cost effectiveness
and technical feasibility.
DOE, the U.S. EPA, State DISC, and CVRWQCB have agreed to a cleanup goal of drinking
water standards (MCLs) for VOCs in ground water in the GSA OU, except as specified below.
This cleanup goal is based on the chemical-specific ARARs (State and Federal MCLs)
established in the Federal Safe Drinking Water Act and California Safe Drinking Water Act.
The Federal and State MCLs for the chemicals of concern in ground water in the GSA OU are
given in Table 9. The most stringent concentration limit, in most cases the State MCL, is the
governing ARAR for each chemical of concern and will be the cleanup goal for ground water
remediation in the GSA.
The CVRWQCB's decision to concur with MCLs as ground water cleanup goals was based
on technical and economic information in the GSA FS. The CVRWQCB stated "LLNL/DOE
presented costs and time needed to cleanup to MCLs and non-detect for TCE. Based on
numerical fate and transport modeling, LLNL/DOE showed that concentrations of TCE would be
below the limit of detection (0.5 ppb [fig/L]) in all but a 12-acre area in the vicinity of the GSA
after 55 years of pumping. The 12-acre area would be below the MCLs, except for an
approximately 100 ft-square area at 5 to 10 ppb (Hg/L). Simulation TCE fate and transport for
an additional 35 years (without pumping) showed TCE contamination at or below 1 ppb (ng/L),
except for about a 100 ft-square area which would be at or below the MCL. LLNL/DOE also
simulate 90 years of pumping, which showed that TCE concentrations would be at or below
1 ppb (fig/L) in all locations. The Board agrees that 35 years of additional pumping for
achieving the small amount of mass removal is not economically feasible." However, if
remediation does not show that cleanup is proceeding as the modeling predicts, remediation
methods will be revisited.
The CVRWQCB and the U.S. EPA do not concur with the selection of MCLs as the cleanup
goal for chloroform and bromodichloromethane, because the MCL for total trihalomethanes is
based on the economics of chlorinating a municipal water supply to remove pathogens and
therefore does not adequately protect the beneficial uses of a drinking water source that has not
been, and may not be, chlorinated. The modeling as described in Appendix E of the GSA
Feasibility Study predicts that TCE in the area where chloroform and bromodichloromethane are
found will be cleaned up to five to ten parts per billion (ppb) after 55 years of pumping. The
agencies predict that this will result in cleanup of chloroform and bromodichloromethane to
1.1 ppb and 0.27 ppb, respectively. If the remediation does not show that cleanup is proceeding
as predicted, the cleanup goals for chloroform and bromodichloromethane will be revisited,
following the procedure to be outlined in the GSA OU Compliance Monitoring and Contingency
Plan.
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The CVRWQCB believes that the California Safe Drinking Water and Toxic Enforcement
Act of 1986, Health and Safety Code Section 25249.5 et seq. (Proposition 65) is an ARAR for
the establishment of in situ ground water cleanup levels. DOE has not included Proposition 65
as an ARAR in this ROD because federal agencies are exempt from its requirements (California
Health and Safety Code Section 25249.11). The CVRWQCB will not dispute the ROD,
however, because the cleanup of the listed constituents will meet or exceed Proposition 65 levels.
Because numerical standards or chemical-specific ARARs for cleanup of contaminants in
soil vapor have not been established, DOE and the regulatory agencies agreed upon a cleanup
goal for soil vapor which is protective of ground water as discussed in Section 2.9.1.2. The
objective is to reduce VOC mass in the vadose zone to levels protective of ground water and
remediate VOCs in the vadose zone to the extent technically and economically feasible to
minimize further degradation of ground water by contaminants in the vadose zone. DOE, U.S.
EPA, and the State disagree on the applicability of SWRCB Resolution No. 92-49 and the
CVRWQCB's Water Quality Control Plan with respect to using water quality objectives to
establish soil vapor cleanup levels. The State concurs with this ROD, however, because it
believes that the standard in Sections 2.9.1.2 and 2.9.3.2 complies with those requirements. This
ROD does not resolve the ARAR status of State requirements regarding the establishment of soil
cleanup levels.
Chapter 15, CCR Title 23, Sections 2550.7 and 2550.10 are chemical-specific ARARs,
which require the monitoring of the effectiveness of remedial actions. In accordance with these
ARARs, in situ concentrations of VOCs in ground water and soil vapor will be measured during
and after the completion of the selected remedy for the GSA OU to monitor its effectiveness in
achieving cleanup goals.
State Board Resolution No. 88-63 (Sources of Drinking Water Policy) designates all ground
and surface water of the State as drinking water except where the TDS is greater than 3,000 ppm,
the water source does not provide sufficient water to supply a single well more than 200 gallons
per day, the water is a geothermal resource or in a waste water conveyance facility, or the water
cannot reasonably be treated for domestic use using either Best Management Practices or best
economically achievable treatment practices.
Chemical-specific ARARs related to the discharges of waste resulting from remediation
activities include: 1) the SWRCB Resolution 68-16, which is applicable to the discharge of
treated ground water from the remediation systems, and 2) the San Joaquin Valley Unified Air
Pollution Control District (SJVUAPCD) Rules 463.5 and 2201 regulating the discharge of
treated vapor. Treated ground water will be discharged according to the requirements of the
NPDES Permit (Order No. 91-052) for the eastern GSA and the Substantive Requirements for
the central GSA. These permits are administered by the CVRWQCB. The discharge standards
under the current permits require that the monthly median VOC concentration in ground water
are reduced to below EPA Method detection limits for VOCs (<0.5 Hg/L), prior to discharge.
Treated vapor will be discharged according to the requirements of the "Authority to Construct"
or "Permit to Operate" issued by the SJVUAPCD, which currently requires that VOC
concentrations in vapor be treated to 6 ppmv, prior to discharge to ambient atmosphere.
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2.10.2. Location-Specific ARARs
Location-specific ARARs are restrictions placed on the concentration of chemicals or
conduct of operations based on the location of a site. Potential location-specific ARARs include
the protection of:
• Wetlands.
• Floodplains.
• Historic landmarks.
• Coastal zones.
• Coastal barriers.
• Rare and endangered species.
• Cultural resources.
The GSA does not contain any historic landmarks, coastal zones, or coastal barriers. No
wetlands have been identified within the area of the GSA where the remedial action would occur.
Although the GSA OU is located adjacent to the 100-year floodplain associated with Corral
Hollow Creek, no portion of Site 300 lies within the floodplain. 22 CCR 66264.18(B)(1) states
that TSD facilities within a 100-year floodplain must be designed, constructed, operated, and
maintained to prevent washout of any hazardous waste by a 100-year flood. If it became
necessary to install POU treatment for water-supply well CON-1, which is located offsite within
the 100-year floodplain, the system would be constructed in accordance with this requirement.
Archaeological and ecological surveys conducted in the GSA are described in Chapter 6 of
the SWRI and the Site 300 EIR/EIS (U.S. DOE, 1992), respectively. Additional surveys to
identify potential cultural resources and the presence of sensitive (rare, threatened, or
endangered) species will be conducted, as necessary, prior to all ground-breaking activities
associated with remediation in the GSA in order to mitigate any adverse impacts of the project.
In addition, the discharge of treated water to Corral Hollow Creek that could affect endangered
species that may be in the California Department of Fish and Game ecological preserve
downstream, is regulated through the NPDES permit for the eastern GSA treatment facility.
2.10.3. Action-Specific ARARs
Action-specific ARARs are usually technology- or activity-based limitations on actions taken
with respect to hazardous wastes. These requirements are triggered by the particular remedial
activities that are selected to accomplish a remedy. For the selected remedy, there are two
action-specific ARARs which are related to: 1) monitoring of the reinjection of treated water,
and 2) the management of hazardous wastes generated as a result of remedial activities. All
treated water to be reinjected will be analyzed/monitored prior to reinjection in accordance with
the requirements of the Safe Drinking Water Act Underground Injection Control Program (40
CFR 144.26-144.27). All hazardous waste generated as the result of the selected remedy,
primarily spent GAC, will be handled in accordance with the requirements of CCR, Title 22,
Chapter 30 and the Health and Safety Code, Sections 25100-25395.
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2.10.4. Other Applicable Standards
There are no ARARs as cleanup standards for contaminants in the vadose zone that may
present an inhalation risk to human health. Therefore, a cumulative potential excess cancer risk
of 10"6 (one in one million) will be used as the cleanup goal for mitigation of VOC inhalation
risk inside Building 875 as specified in the NCP (U.S. EPA, 1990a).
As discussed in Section 2.11.2, the selected remedy meets ARARs by actively remediating
VOCs in soil and ground water to protect human health and the environment.
2.11. Statutory Determinations
The selected response action for the GSA OU satisfies the mandates of CERCLA
Section 121. The remedy will:
• Protect human health by reducing risk from soil vapor inhalation and by achieving
ground water remediation goals.
• Comply with ARARs.
• Provide both short- and long-term effectiveness.
• Reduce contaminant toxicity, mobility, or volume as a principal element.
• Be readily implementable.
• Provide the most cost-effective means of achieving remediation goals.
DOE, U.S. EPA, CVRWQCB, and DTSC believe that among the three proposed remedial
alternatives, Alternative 3b provides the best balance of trade-offs with respect to the CERCLA
evaluation criteria. Site 300 will remain under the control and ownership of DOE for the
foreseeable future. This is a major factor in defining the scope of the remedy proposed in this
ROD. A brief description of how the selected remedy satisfies each of these statutory
requirements, as well as state and community acceptance, is provided below.
2.11.1. Overall Protection of Human Health and the Environment
The selected remedy uses exposure control methods, such as contingency POU treatment and
administrative controls, to provide initial protection to human health. It also provides long-term
protection to human health by restoring and protecting the beneficial use of the Tnbsj regional
aquifer and potential beneficial use of the alluvial aquifer through active remediation to reduce
VOC concentrations in ground water to MCLs.
The selected remedy prevents potential inhalation of VOCs above health-based
concentrations in Building 875 by reducing soil vapor VOC concentrations through soil vapor
extraction.
All extracted soil vapor and ground water will be treated before discharge to the
environment. Soil vapor and ground water monitoring will document the progress and
permanence of all remediation methods.
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The selected remedy employs ecological surveys and appropriate response actions, if
necessary, to protect the environment. By actively reducing VOC concentrations in soil vapor
and ground water, potential future ecological risks are mitigated.
In accordance with a DOE Secretarial Policy issued in June 1994, National Environmental
Policy Act (NEPA) values contained in the Environmental Considerations chapter of the GSA
FS satisfy the requirements for CERCLA-NEPA integration. As part of these requirements, the
potential impacts on the existing onsite and offsite environment due to implementation of the
remedial alternatives were evaluated. No significant adverse impacts due to implementation of
the alternatives were identified.
2.11.2. Compliance with ARARs
Federal and State chemical-, location-, and action-specific ARARs affecting the selected
remedy are described in Table 11. The selected remedy meets all ARARs. Ground water and
soil vapor extraction will reduce VOC concentrations to MCLs in ground water in the GSA OU,
as well as reduce inhalation risk inside Building 875 to health-protective levels.
2.11.3. Short-Term Effectiveness
The selected remedy immediately protects the public from existing exposure pathways
through exposure controls: contingency POU treatment and administrative controls. It also uses
ground water and soil vapor extraction to continue to remove VOC mass and reduce VOC
concentrations in ground water and soil vapor. It provides measures for the protection of site
workers and the community during remedial actions. No adverse environmental impacts are
anticipated.
2.11.4. Long-Term Effectiveness and Utilization of Permanent Solutions
The selected remedy provides long-term effectiveness through contaminant mass removal
that will: 1) reduce VOC concentrations to MCLs in all affected ground water, and 2) reduce
VOC soil vapor concentrations to levels protective of ground water and to acceptable health
inhalation risk levels. Monitoring will be continued for five years after discontinuing ground
water extraction to ensure long-term effectiveness and permanence.
2.11.5. Reduction of Contaminant Toxicity, Mobility, or Volume as a
Principal Element
Contaminant toxicity, mobility, and volume in the soil and ground water will be reduced
irreversibly by ground water and soil vapor extraction. In addition, SVE will significantly
reduce the toxicity, mobility, and volume of both dissolved and undissolved (DNAPL)
contaminants in the subsurface, enhance the progress of VOC removal, and be more protective of
the environment than if only ground water extraction was used.
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2.11.6. Implementability
The selected remedy can be readily implemented utilizing existing soil vapor and ground
water extraction and treatment systems that are permitted and operating in the GSA.
Modifications to these systems are readily implementable.
2.11.7. Cost Effectiveness
DOE, U.S. EPA, CVRWQCB, and DISC agree that Alternative 3b provides the most cost-
effective means of remediating VOCs in soil and ground water to levels protective of human
health and the environment. The cost of this alternative was estimated on the basis of a
preliminary engineering design to reduce inhalation risk, remove VOC mass, and reduce VOC
concentrations in ground water to MCLs.
2.11.8. State Acceptance
The California DTSC and CVRWQCB provided ARARs which were used as the basis for
developing the selected remedy. These State agencies reviewed and evaluated the remedial
technologies and alternatives and participated in the selection of the final remedy and provided
oversight and enforcement of state environmental regulations. In addition, the regulatory
agencies have monitored and reviewed public acceptance of the final selected remedy.
2.11.9. Community Acceptance
Public comments concerning the selected remedy have been considered and used, as
appropriate, in the preparation of this ROD. All public comments are addressed in the
Responsiveness Summary section of this document.
Any proposed changes to the ROD, such as the implementation of new remedial alternatives
or innovative technologies, re-evaluation of the technical and economic feasibility of achieving
cleanup goals, etc., will be submitted to the regulatory agencies for review and approval.
Community members will be informed of any ROD change, and would be provided with the
opportunity to comment on significant or fundamental ROD changes. Following EPA guidelines
(U.S. EPA, 1991), the lead agency determines if the proposed ROD change is: 1) nonsignificant
or minor, 2) significant, or 3) fundamental.
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3. Responsiveness Summary
This section responds to public comments directed to DOE, LLNL, U.S. EPA, and the State
of California regarding the Proposed Plan for remediation of the GSA OU. Responses to
community comments and concerns are incorporated into this ROD.
The public comment period on the Proposed Plan began April 10, 1996, and ended May 10,
1996. On April 24, 1996, DOE/LLNL and the regulatory agencies held a public meeting at the
Tracy Inn in Tracy, California to present the proposed remediation plan and allow the public to
ask questions and comment on the preferred remedial alternative. Representatives from LLNL
summarized the information presented in the FS and Proposed Plan. Following the presentation,
three members of the public read their concerns into the formal public record. Although no
letters were received during the Proposed Plan comment period, members of the Tri-Valley
Citizens Against a Radioactive Environment (CAREs) provided a written record of their meeting
comments. The meeting transcript and a copy of the written concerns are available to the public
at the LLNL Visitors Center and the Tracy Public Library.
3.1. Organization of the Responsiveness Summary
This Responsiveness Summary is organized to clearly present the breadth of public concerns
while minimizing repetition. In keeping with EPA Superfund guidance and accepted practice,
comments are grouped by subject. Whenever possible, comments are summarized verbatim
from either the meeting transcript or written comments.
Public comments are grouped into the following sections:
• Selected Remedial Action.
• General Comments.
3.2. Summary of Public Comments and Responses
3.2.1. Selected Remedial Action
Comment 1:
Before the Proposed Plan is approved, it is important that the monitoring plan be specified,
(number of wells, depth of wells, frequency of sampling, duration of sampling, approximate
location of wells) and that a contingency plan be specified which delineates what the Lab is
committed to do should it find that the plume is moving, or is not being remediated in the time-
frame expected. This should be similar in content to the way contingency was addressed in the
document entitled "Remedial Alternatives for the Building 815 Operable Unit. " There, specific
information regarding what the Lab was prepared to do if the plume migrated past a certain
point was established.
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Response to Comment No. 1:
A preliminary monitoring plan was presented in the FS to support cost estimates for each
remedial alternative. This preliminary monitoring plan presented the number of wells and the
frequency and duration of sampling. The depths and approximate locations of these wells were
also included in the FS. This information was not reiterated in the Proposed Plan, which is
intended to be a brief summary document. Consistent with EPA guidance and practice at other
U.S. EPA Superfund sites, the GSA monitoring program will be presented in the Remedial
Design document. As specified in the Site 300 FFA, a discussion of the schedule for the
Remedial Design for the GSA will be initiated within 15 days of the signing of the Final ROD,
which is scheduled for January 1997.
A formal review of remediation progress is required to be conducted at least every five years
to ensure that the selected remedy is effective and continues to adequately protect human health
and the environment. However, the evaluation of the progress of remediation will be an on-
going, continuous process. Progress of site cleanup will be published in periodic progress
reports. If monitoring data indicate that the selected remedy is not effectively remediating the
site, DOE/LLNL and the regulatory agencies will evaluate whether to consider another remedial
alternative.
Comment 2:
The plan should contain milestones by which the success of the subsequent remediation can
be evaluated. In almost all Superfund cleanup projects, commitments and milestones concerning
the cleanup performance (e.g., timing of cleanup, how much contaminant will be removed) are
disregarded in Records of Decision. We regard this as a fundamental problem with the
government's approach to CERCLA enforcement. For example, we suggest that a timetable for
cleanup be established. This could be based on performance milestones such as the amount of
contaminant mass that is removed from the soil and groundwater within an expected time period,
and regulatory milestones such as achieving cleanup standards or showing a trend towards
meeting cleanup standards. This timetable would then be used to monitor the performance of
cleanup, and provide interested parties with some idea how cleanup will progress. As it now
stands, after a final ROD is signed, the only legal requirements are that substantial on-site
remedial action be commenced within 15 months and that the cleanup program be subject to a
five-year review. It is important that the Proposed Plan contain a measurable schedule and
performance standards which can be verified.
Response to Comment No. 2:
Consistent with U.S. EPA Superfund guidance and as specified by the CERCLA process,
schedules and performance milestones will be presented in the GSA Remedial Design document.
As specified in the Site 300 FFA, a discussion of the schedule for the Remedial Design
document for the GSA will be initiated within 15 days of the signing of the ROD, which is
scheduled for January 1997.
DOE will make the Remedial Design document available to the public as part of the
CERCLA public participation process. The public will have an opportunity to review and
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comment on the Remedial Design document. If concerns or issues concerning the Remedial
Design document are identified on the part of the public and regulatory agencies, a public
meeting may be considered.
The Remedial Design document will define in detail the technical parameters, design criteria
and components, and assumptions of the Remedial Action including:
1. Waste characterization,
2. Pretreatment requirements,
3. Volume and types of each medium requiring treatment,
4. Treatment schemes, rates, and required qualities of waste water streams,
5. Performance standards,
6. Long-term performance monitoring and O&M requirements,
7. Compliance with all ARARs, codes, and standards,
8. Technical factors of importance to the design and construction,
9. Construction schedule,
10. Cost estimates,
11. Variances with the ROD, if necessary,
12. Land acquisition and easement requirements, and
13. Value Engineering Screening (including an evaluation of cost and function relationships,
concentrating on high-cost areas.
The final Remedial Design must be approved by the regulatory agencies before initiating the
Remedial Action. Cleanup standards are included in Section 2.9.1 of this ROD.
A formal review of remediation progress is required to be conducted at least every five years
to ensure that the selected remedy is effective and continues to adequately protect human health
and the environment. However, the evaluation of the progress of remediation will be an on-
going, continuous process.
If the selected remedy fails to meet the criteria set forth in the design documents, DOE/LLNL
and the regulatory agencies will evaluate whether to consider another remedial alternative.
Comment 3:
I want to emphasize the need for contaminant reduction milestones as a method of
determining not only how well the cleanup is doing, but whether or not the cleanup's budget
year to year is sufficient. Right now, and this is a problem we are running into at the Main Site
to some extent, and in other sites as well, where the milestones are defined as production of
documents, we are going to have a remedial design document by thus and such a date or the
milestone is the putting in of a monitoring well or the construction of an extraction well
irrespective of whether those things alone. Well obviously the production of the document
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doesn 't actually remediate the site, irrespective of whether those things alone together are going
to accomplish the cleanup and keep it on schedule.
In saying you have a 55-year cleanup time, somebody has done a curve. I mean, you are
figuring you are going to peg down the contaminant levels by certain amounts to get to cleanup
in 55 years. If you made them explicit, that would give the citizens a way to track how the
cleanup is doing, say, in five-year increments and that the cleanup was falling behind, we would
then have something we could use in saying our community needs some more money to get this
back on track. None of us wants to wait 55 years, which means our children and in some cases
our children's children will then say oh, that wasn 't enough, it isn 't cleaned up.
So we really (the public) need this stuff to be codified in the Record of Decision to help watch
dog and ensure a full cleanup. As Peter mentioned, mass removal milestones is another entree
into the same type of result.
Response to Comment No. 3:
As stated in the response to Comment 2, schedules and performance milestones will be
presented in the design document; consistent with U.S. EPA Superfund guidance and as
specified by the CERCLA process. Budgetary issues are discussed in the response to
Comment 17.
The 55-year projected time to reduce VOC ground water concentrations in the central GSA
to MCLs was based on remediation and contaminant fate and transport modeling presented in the
GSA FS. The modeling for the selected remedy (Alternative 3b) was discussed in Section
E-2.9.2.2 of the FS, and presented simulated VOC ground water concentrations for 10, 30, 55,
and 90 years after initiation of remediation.
The modeling indicated that the selected remedy utilized the optimum number and
configuration of extraction wells for the most cost- and time-effective remediation of the GSA.
Although this modeling was conducted primarily for the purposes of determining cost, it
estimates remediation progress. Additional modeling using current data may be conducted
during the five-year review to evaluate remediation progress.
Comment 4:
The Proposed Plan or the ROD should identify criteria it will use to determine whether a
remedy should be replaced with a new remedy, or that remediation should be discontinued. In
the case of the former, there are many new development activities which may improve upon the
selected remedy. At some time in the future there may be a decision to replace old technology.
The (Proposed Plan) or the ROD should outline what decision criteria will be used to re-assess
the proposed technology. In addition, there has been a trend at some sites to stop remediation
on the grounds of "Technical Impracticability". The (Proposed Plan) or the ROD should
outline the decision criteria that would be used to make such a determination, as the decision
will not be subject to the same level of public scrutiny as is the ROD.
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Response to Comment No. 4:
The decision criteria that will be used to determine:
1. When remediation should be discontinued are discussed in Section 2.9.3 of the ROD.
2. Whether to replace the technologies outlined in the ROD are discussed in Section 2.9.4 of
the ROD.
3. When to cease remediation activities based on Technical Impracticability are discussed in
Section 2.9.3 of the ROD.
U.S. EPA's OSWER Directive 9234.2-25, "Guidance for Evaluating the Technical
Impracticability of Ground Water Restoration" (EPA, 1993c), provides guidance for evaluating
Technical Impracticability. If the cleanup levels are changed due to Technical Impracticability,
an ARARs waiver will be obtained and a ROD amendment will be necessary.
Throughout the remediation process, innovative remediation technologies will be considered
to enhance VOC mass removal and treatment of soil vapor, as discussed in Section 2.9.4.
In addition, a review will be conducted every five years after commencement of the remedial
action to ensure that the remedy continues to provide adequate protection of human health and
the environment.
Comment 5:
If the Proposed Plan could contain some more detail about the types of treatment
technologies that are being considered, a little bit of data on the effectiveness of the treatment
technologies being used as pilot projects so that we could then discuss in greater detail, what
kind of suite of treatment technologies we might want to codify in the Record of Decision. That
would make for a much higher sort of level of decision.
Response to Comment No. 5:
The types of treatment technologies considered for implementation at the GSA, including the
technologies included in the selected remedy, were screened and discussed in detail in the GSA
FS. The effectiveness of the existing treatment systems was also evaluated and discussed in the
GSA FS. The Proposed Plan is designed to be a brief summary of the major components of the
evaluated alternatives and the preferred remedy that are discussed in detail in the FS.
Comment 6:
The criteria for choosing treatment technologies need to be a part of the Record of Decision.
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Response to Comment No. 6:
Consistent with U.S. EPA Superfund guidance, the criteria for choosing treatment
technologies was presented in the GSA FS, where each treatment technology was screened and
discussed. See also response to Comment No. 3.
Comment 7:
Remedial action objectives should be identified in the Proposed Plan and include:
i) Protect human health and ecological receptors from contact with contaminated
groundwater, soil or air;
ii) Attain the preliminary remediation goals (PRGs) set by EPA Region 9. (PRGs are
remediation goals with an estimated health risk of one in one million additional cancer
deaths);
Hi) Conduct cleanup in such a way as to minimize time for remediation;
iv) In the Central GSA, continue efforts to remove contaminant mass from the ground water
and soil and locate the source of dense non-aqueous phase liquid (DNAPL).
Response to Comment No. 7:
i) Section 2.5 of the FS defines Remedial Action Objectives (RAOs) which are media-
specific goals for protecting human health and the environment. EPA guidance indicates
that RAOs are to specify exposure routes for which potentially unacceptable risk has
been identified, contaminants of concern, and an acceptable contaminant concentration or
range of concentrations. We have addressed these points in the RAOs. Cleanup goals
are discussed in Chapter 4 of the FS and are specified in more detail in Section 2.9.1 of
this ROD.
ii) The U.S. EPA, and the State DTSC, and CVRWQCB have concurred with a cleanup goal
of MCLs for VOCs in ground water in the GSA OU. The CVRWQCB's decision to
concur with MCLs as ground water cleanup goals was based on technical and economic
information in the Final FS for the GSA OU. The CVRWQCB stated "LLNL/DOE
presented costs and time needed to cleanup to MCLs and nondetectable for TCE. Based
on numerical fate and transport modeling, LLNL/DOE showed that concentrations of
TCE would be below the limit of detection (0.5 ppb [jig/L]) in all but a 12-acre area in
the vicinity of the GSA after 55 years of pumping. The 12-acre area would be below the
MCLs, except for an approximately 100 ft-square area at 5 to 10 ppb (u.g/L). Simulation
TCE fate and transport for an additional 35 years (without pumping) showed TCE
contamination at or below 1 ppb (^ig/L) except for about a 100 ft-square area, which
would be at or below the MCL. LLNL/DOE also simulate 90 years of pumping, which
showed that TCE concentrations would be at or below 1 ppb (Hg/L) in all locations. The
Board agrees that 35 years of additional pumping for achieving the small amount of mass
removal is not economically feasible. However, LLNL/DOE will be required to review
the remedial system every five years to determine if the remedial objectives are being
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UCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
met. LLNL/DOE will optimize the system or propose an alternative remedial method if
the plume is not being remediated as projected."
MCLs are health based and equivalent to an excess cancer risk of 10"6, or one in one
million, with consideration given to technologic and economic factors. U.S. EPA Region
IX Preliminary Remediation Goals, according to EPA, "can be used as a rapid reference
for screening concentrations in environmental media, as 'triggers' for further
investigation at CERCLA/RCRA sites, and as initial cleanup goals, if applicable." The
NCP (U.S. EPA, 1990a) states that "PRGs should be modified, as necessary, as more
information becomes available during the RI/FS. Final remediation goals will be
determined when the remedy is selected." Remediation goals are developed by
considering ARARs under Federal or State environmental laws. The NCP also states that
the "10"6 risk level shall be used as the point-of-departure for determining remediation
goals for alternatives when ARARs are not available."
iii) The preferred remedy is designed to achieve soil and ground water cleanup goals in a
time-effective manner using proven, implementable technologies. Other remediation
scenarios were evaluated, such as installing more wells to determine if an increased
ground water extraction rate would expedite cleanup. Modeling indicated that the
selected remedy provided the most expeditious, cost-effective means of remediating the
GSA OU.
iv) The selected remedy (Alternative 3b) includes both ground water and soil vapor
extraction to remove contaminant mass from ground water and soil in the central GSA.
Based on historical and sampling data, DNAPLs may be present in the vicinity of the
Building 875 dry well pad where the SVE remediation efforts are concentrated. The only
wells in the GSA where ground water sample data indicate the possible presence of
DNAPLs (TCE concentrations >11,000 ppb) are wells W-875-07, -08, -09, -10, -11, -15,
and W-7I. These wells are all located in the Building 875 dry well pad area in the central
GSA. The source of DNAPLs in this area was the wastewater disposed in the two former
dry wells, 875-S1 and 875-S2, located south of Building 875. No other wells in the GSA
have contained VOCs in ground water in concentrations indicative of DNAPLs, including
wells located at other source areas. We have therefore concluded that the DNAPLs are
confined to the Building 875 dry well pad area in the central GSA. SVE has been
identified as a technology that can effectively remediate DNAPLs in the vadose zone.
Throughout the life of the remediation project, continued efforts will be made to evaluate
whether DNAPLs act as a continuing source of contamination. The methodology and
schedule for the evaluation of DNAPLs will be included in the remedial design
document. The objective of these investigations is to validate whether the assessment of
the location of DNAPLs, as well as efforts to remediate DNAPLs, are properly focused.
Comment 8:
The Proposed Plan should include a continued search for the location of DNAPLs in the
central GSA, and the testing and/or development of new technologies to extract DNAPL, until
monitoring conclusively proves that they are no longer present in the area. It does not appear
that the DNAPL problem will be solved by the Proposed Plan. Without removal of DNAPL, the
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
site will act as a continuing source of contamination, and may reverse the progress that has been
made in cleanup over the past several years. While DNAPL or potential DNAPL exists at many
sites that I am aware of, solutions are elusive without knowing the precise location. I suggest the
(Proposed Plan) identify how many quarters (or years) that monitoring will be required to show
that DNAPLs are no longer present.
Response to Comment No. 8:
As discussed in Chapters 1 and 4 of the FS, residual DNAPLs may exist in soil in the
dewatered zone and/or vadose zone in the central GSA in the vicinity of the Building 875 dry
well pad, as discussed in the response to Comment No. 7 (iv). Data from other nearby wells and
wells in other source areas allows us to conclude that DNAPLs are confined to the Building 875
dry well area.
The preferred remedy (Alternative 3b) includes SVE, which has been identified as a
technology that can effectively remediate DNAPLs in the vadose zone (U.S. EPA, 1992d,
1993b). Historical sampling data indicate that DNAPLs may be in the vicinity of the
Building 875 dry well pad where the SVE remediation efforts are concentrated. Ground water,
soil, and soil vapor data collected from other release areas do not indicate that DNAPLs are
present. DOE/LLNL will continue to investigate and evaluate innovative technologies that may
be considered for application at the GSA if they could be implemented cost effectively and
expedite remediation. Throughout the life of the remediation project, continued efforts will be
made to evaluate whether DNAPLs act as a continuing source of contamination. The
methodology and schedule for the evaluation of DNAPLs will be included in the remedial design
document. The objective of these investigations is to validate whether the assessment of the
location of DNAPLs, as well as efforts to remediate DNAPLs, are properly focused.
In general, if a ground water VOC concentration is 1 to 10% of the solubility of that VOC in
ground water, then a DNAPL may be present. Because the aqueous solubility of TCE is
1,100,000 |ig/L, TCE concentrations in the range of 11,000 to 110,000 \iglL or greater would
indicate DNAPL. The cleanup goals established for ground water (i.e., 5 fig/L for TCE) are well
below the concentrations indicative of DNAPLs (11,000 \ngfL for TCE). When VOC
concentrations in ground water have been reduced to cleanup goals (MCLs), the ground water
extraction and treatment system(s) will be shut off and placed on stand-by. Modeling indicates
that VOC concentrations in ground water in the central GSA should be reduced to MCLs within
55 years following the initiation of remediation. Ground water in the central GSA will continue
to be monitored for a period of five years following shutdown of the system. This will allow
tracking of ground water VOC concentration trends in the Building 875 dry well pad area to
determine if: 1) ground water VOC concentrations in the area indicate DNAPLs, and 2) the
ground water remediation goal has been attained and maintained. Should VOC concentrations in
ground water "rebound" or increase above cleanup goals, reinitiation of remediation efforts will
be discussed with the regulatory agencies.
Comment 9:
I am concerned on a number of levels. One of them, let me just use as an example the
problem with dense non-aqueous phase liquids with the concentrations of TCE that you have at
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Site 300, there probably are globs of pure TCE in there and as those dissolve over time it is
going to continue as its own source of contamination and in order to get at those, you guys need
money for something called source investigation. John Ziagos will remember I am big on
advocating money for source investigation to make sure that you have got the information you
need so that you put in the right cleanup technologies in the right places to actually achieve a
cleanup. I think it's penny wise and pound foolish to neglect source investigation, so I am
looking at the Department of Energy's fiscal year 1998 draft priority list and for the one that's
for the Livermore Lab Main Site and Site 300. The first time I see source investigation, let me
just say for the record, this line here is put at a target of what is gonna be 19.4 million dollars
they plan to ask for for FY1998 and everything that falls below this line they are not even gonna
ask for money for and the first time source investigation is mentioned is about ten listings below
the line. So, there is not even any consideration that DOE is going to even ask for money that
will adequately fund source investigation in the time frame when you are really gonna need that
money. So codifying something in the'Record of Decision is a way to ensure that that gets
bumped up, because then it becomes a legal requirement and it suddenly is part of what becomes
necessary and not optional and in my opinion, some of these things, I mean, all of these that I am
talking about are necessary.
So then I looked at how it rates in the field office where the lab has to compete against the
other DOE facilities and its four from the bottom on page 5. So if it isn 't codified in the Record
of Decision, I kind of think that you are probably not gonna get the money to do it and you are
going to have ongoing problems that will threaten the entire cleanup because there is not the
money to go out and do the source investigation needed to fund the DNAPLs and also some of
the other important parameters before cleanup can be accomplished.
Response to Comment No. 9:
Based on historical sampling data described in the response to Comment No. 7 (iv) and our
extensive source investigations presented in the SWRI and FS, we have concluded that DNAPLs
are confined to the Building 875 dry well pad area in the central GSA. The source of potential
DNAPLs in this area was the wastewater disposed in the two former dry wells 875-S1 and
875-S2 located south of Building 875. No other wells in the GSA have contained VOCs in
ground water indicative of the presence of DNAPLs. Because the source of the DNAPLs has
been confirmed as the two former dry wells 875-S1 and 875-S2, located south of Building 875,
and analytical data confirms that the DNAPLs are confined to the vicinity of the Building 875
dry well pad, no additional source investigation for DNAPLs in the GSA is planned at this time.
TCE concentrations in ground water in GSA monitor wells will be monitored throughout the life
of remediation. If future ground water analytic data indicate that DNAPLs have migrated or are
present in other areas of the GSA, changes to the remediation system(s) to address the
presence/remediation of DNAPLs will be considered at that time.
Throughout the life of the remediation project, continued efforts will be made to evaluate
whether DNAPLs act as a continuing source of contamination. The methodology and schedule
for the evaluation of DNAPLs will be included in the remedial design document. The objective
of these investigations is to validate whether the assessment of the location of DNAPLs, as well
as efforts to remediate DNAPLs, are properly focused.
1-97/12406 l:GSAROD:rid 3-9
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Comment 10:
I think essentially the points that both Peter Strauss and Marylia Kelly have made about
looking for these DNAPLs, as they are called, looking for the source of contamination which
obviously could have an impact on the cleanup and how fast or how easy it would be to achieve
certain milestones, which I do believe should be in place, are critical.
Response to Comment No. 10:
See responses to Comments Nos. 7 (iv) and 9. The potential presence of DNAPLs in the
central GSA was factored into the ground water modeling conducted for the selected remedy.
This modeling was the basis for estimating cleanup time for the selected remedy.
Comment 11:
The Lab must demonstrate that natural attenuation is actually occurring at this OU. At the
main site, early modeling factored in natural attenuation to calculate cleanup time. A later study
invalidated this assumption. There has not been, to the best of my knowledge, conclusive
evidence that natural attenuation is a relevant factor in the cleanup ofTCE at Site 300, although
models on the length of time for cleanup may use this assumption. For example, vinyl chloride is
a natural breakdown product ofTCE. TCE has been found at extremely high concentrations in
the GSA, yet the baseline health risk assessment does not include an assessment of vinyl chloride
because it has not been found at Site 300. Vinyl chloride is a known human carcinogen, and is
harmful at very low concentrations, i.e., 0.5 ppb is the drinking water standard for vinyl
chloride.
Response to Comment No. 11:
The selected remedy (Alternative 3b) does not rely on natural attenuation as a component of
the remediation of soil or ground water in the GSA. This remedy provides for active remediation
to reduce VOC concentrations in soil and ground water to levels protective of human health and
the environment.
Comment 12:
Something that our group, working with a hydrologist, took a look at for the Main Site
cleanup which you will recall, John Ziagos, but I would like to see you folks take a crack at this
for the GSA and that is taking a look at, okay, you have a cost estimate in present dollars. What
percentage of that is your capital costs and what percentage is M&O costs? How many
extraction wells, etc. do you plan to put in? How many could you put in optimally and if so, how
would that cut down on your 55-year cleanup time and, therefore, perhaps really cut down on
the amount of cost for the cleanup overall? If it became a 30-year cleanup with some more
extraction wells instead of a 55-year cleanup, perhaps the overall cost would go down
dramatically. I suspect that that's true. Again, this is information, that if it were discussed and
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
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.
l-97/124061:GSAROD:rtd 3-11
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Comment 14:
The cleanup standards for TCE and other VOCs should be more stringent. Because the GSA
connects with the regional aquifer, we believe that the cleanup standard should be set at the
incremental lifetime cancer risk (ILCR) of one in one million (1 x 10~^). CERCLA guidelines
require cleanup to I x 1&-4 to 1 x 1Q-6 ILCR. The Preliminary Remediation Goal (PRG)for
TCE is the most current attempt to define the 1 x 1Q-6 cleanup standard. The PRG for TCE is
1.8 ppb. We believe that PRGs should be adopted for VOCs that can migrate to the regional
aquifer. I note that at two other Superfund sites where I serve as the Technical Advisor, the
PRPs (in one case a private party, in another the DoD and the City of Tucson) have adopted a
cleanup standard based on reducing risk to one in one million. Thus, it is clear that EPA and
responsible parties can adopt these stricter standards.
Response to Comment No. 14:
The U.S. EPA, and the State DISC, and CVRWQCB have concurred with a cleanup goal of
MCLs for VOCs in ground water in the GSA OU. The CVRWQCB's decision to concur with
MCLs as ground water cleanup goals was based on technical and economic information in the
Final FS for the GSA OU. The CVRWQCB stated "LLNL/DOE presented costs and time
needed to clean up to MCLs and non-detectable TCE. Based on numerical fate and transport
modeling, LLNL/DOE showed that concentrations of TCE would be below the limit of detection
(0.5 ppb [^g/L]) in all but a 12-acre area in the vicinity of the GSA after 55 years of pumping.
The 12-acre area would be below the MCLs, except for an approximately 100 ft-square area at 5
to 10 ppb (|ig/L). Simulation TCE fate and transport for an additional 35 years (without
pumping) showed TCE contamination at or below 1 ppb (^ig/L) except for about a 100 ft-square
area, which would be at or below the MCL. LLNL/DOE also simulate 90 years of pumping,
which showed that TCE concentrations would be at or below 1 ppb (Hg/L) in all locations. The
Board agrees that 35 years of additional pumping for achieving the small amount of mass
removal is not economically feasible. However, LLNL/DOE will be required to review the
remedial system every five years to determine if the remedial objectives are being met.
LLNL/DOE will optimize the system or propose an alternative remedial method if the plume is
not being remediated as projected."
MCLs are health based and equivalent to an excess cancer risk of 10-6, or one in one million,
with consideration given to technologic and economic factors. U.S. EPA Region IX Preliminary
Remediation Goals, according to EPA, "can be used as a rapid reference for screening
concentrations in environmental media, as 'triggers' for further investigation at CERCLA/RCRA
sites, and as initial cleanup goals, if applicable." The NCP (U.S. EPA, 1990a) states that "PRGs
should be modified, as necessary, as more information becomes available during the RI/FS.
Final remediation goals will be determined when the remedy is selected." Remediation goals are
developed by considering ARARs under Federal or State environmental laws. The NCP also
states that the "10~6 risk level shall be used as the point-of-departure for determining remediation
goals for alternatives when ARARs are not available."
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UCRL-AR-124061 Final ROD for the GSA Operable Unit. Site 300 January 1997
3.2.2. General Comments
Comment 15:
Also, as a general comment, I would like to say that for each of the areas of Site 300, the
DOE and the lab and the regulators would do well to interface with the DOE folks who are
preparing the waste management programmatic environmental impact statement which gives as
one of the potential alternatives, the burial of large amounts of ash from mixed waste and low
level radioactive waste at Site 300 and how that potential burial of waste would impact the
cleanup is something that they didn 't look at in the waste management PEIS and that was one of
our comments on that, but it's also something that you then can't incorporate in talking about
the cleanup of these various operable units because, in fact, they didn't even mention where they
planned to dump it at Site 300. So for each of these, that is a question for you guys to ask and
get some clarification, and if you don't think dumping a lot of radioactive and still possibly toxic
ash is going to aid the cleanup, you might have some allies in the citizens group on that.
Response to Comment No. 15:
Comment noted.
Comment 16:
One last overarching issue, and there is no delicate way to bring it up so I will just bring it
up bluntly. Our group is really concerned about some of the changes that are being considered
in the Superfund laws and in particular, some of the changes that would affect the Livermore lab
cleanup wherein if the state standard was stricter than the federal standard, the federal standard
would become the only thing that the lab would have to clean up to. There are a number of
areas where the Regional Water Quality Control Board and the state DTSC have stricter
standards than the federal EPA and achieving those standards is an important part of achieving
an actual cleanup and so what I think should be investigated is the extent to which writing those
things in the Record of Decision will be one way of protecting against having the standards be
lowered as the cleanup goes on, and as we all know, once the standards change, the
Departments of Energy's target changes and so that target, in terms of how clean is clean and
what they think they need to clean up to is in danger of becoming lower and lower and the
Record of Decision is the method that I see to ensure that today's cleanup standards are the
cleanup standard's that are met.
Response to Comment No. 16:
If Federal or State regulations were to change in the future, DOE and the regulatory agencies
would discuss how these changes might affect cleanup. The community would be informed of
any regulatory changes that affect cleanup at Site 300. Any proposed changes to the ROD must
be submitted to the regulatory agencies for review and approval. Following EPA guidelines
(U.S. EPA, 1991), the lead agency determines if the proposed ROD change is: 1) nonsignificant
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UCRL-AR-124061 Final ROD for The GSA Operable Unit, Site 300 January 1997
or minor, 2) significant, or 3) fundamental. Community members would be informed of any
ROD change, and would be provided with the opportunity to comment on significant or
fundamental ROD changes.
Comment 17:
Our group has talked a number of times of the need for stable long-term funding and budget
commitments. Having some kind of budget schedule for the preferred alternative and any other
alternative time scenarios would be very useful for citizens to be able to monitor the commitment
of the DOE and the lab to the cleanup as well as in combination with achievement milestones
and whether they are on track with that, whether the funding is adequate and so 7 would argue
for some kind of additional information to be included on the budgetary aspect over time.
Response to Comment No. 17:
DOE cannot legally commit to funding cleanup or any other activities beyond the current
budget year appropriation. However, DOE places a high priority on risk reduction, compliance,
and associated environmental cleanup in its annual budget submittals. DOE understands that
cleanup delays will likely increase the overall cost of the LLNL cleanup as well as other
facilities, so it is in DOE's best interest to support an adequately funded and progressive cleanup
effort through its annual Congressional budget request each year. DOE does commit to request
from Congress, through the Office of Management and Budget, funding necessary to control and
remediate contaminant plumes, both on and offsite. In addition, DOE is also committed to
removing contaminants as efficiently as possible using available technologies within budgeting
allocations.
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References
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
References
Anspaugh, L. R., J. H. Shinn, P. L. Phelps and N. C. Kennedy (1915), "Resuspension and
Redistribution of Plutonium in Soils." Health Phys. 29.
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Hwang, S. T., J. W. Falco, and C. H. Nauman (1986), Development of Advisory Levels for
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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
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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
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Turner, D. B. (1982), Workbook of Atmospheric Dispersion Estimates, Office of Air Programs,
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of Energy, Washington, D.C. (DOE/EIS-0157).
U.S. DOE/LLNL (1996), The Proposed Plan for Remediation of the Lawrence Livermore National
Laboratory Site 300 General Services Area, Lawrence Livermore National Laboratory,
Livermore, Calif. (UCRL-AR-122585).
U.S. EPA (1989a), Risk Assessment Guidance for Superfund, Vol. I: Human Health Evaluation
Manual, Interim Final, Office of Emergency and Remedial Response, U.S. Environmental
Protection Agency, Washington, D.C. (EPA/540/1-89/002).
U.S. EPA (1989b), Risk Assessment Guidance for Superfund, Vol. II: Human Health Evaluation
Manual, Interim Final, Office of Emergency and Remedial Response, U.S. Environmental
Protection Agency, Washington, D.C. (EPA/540/1-89/001).
U.S. EPA (1990a), "National Oil and Hazardous Substances Pollution Contingency Plan, Final
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U.S. EPA (1990b), Exposure Factors Handbook, Office of Health and Environmental
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R-l
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
U.S. EPA (1991), Risk Assessment Guidance for Superfund, Vol. I: Human Health Evaluation
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April 16-18, 1991, Office of Research and Development, U.S. Environmental Protection
Agency, Washington, D.C. (EPA/600/R-92/030).
U.S. EPA (1993a), Memorandum from D. Stralka, Ph.D., U.S. Environmental Protection Agency
Region DC, to L. Tan, Remedial Project Manager, U.S. Environmental Protection Agency
Region IX, regarding a 'Technical request from Linda Hall at Lawrence Livermore National
Laboratory" for toxicity values for PCE, TCE, and tetrahydrofuran, dated February 25, 1993.
U.S. EPA (1993b), Seminar on Characterizing and Remediating Dense Nonaqueous Phase
Liquids at Hazardous Sites, Office of Research and Development, U.S. Environmental
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Environmental Protection Agency, Washington, D.C. (OSWER Directive 9234.2-25).
Webster-Scholten, C. P., Ed. (1994), Final Site-Wide Remedial Investigation Report, Lawrence
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Wilson, J. L., and P. J. Miller (1978), 'Two-Dimensional Plume in Uniform Ground-Water
Flow," Journal of the Hydraulics Division, Proceedings of the American Society of Civil
Engineers, 104(HY4), pp. 503-514.
R-2
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Figures
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UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
1997
Miles
0 5 10 15 20
ERD-GSA-ROO-0001
Figure 1. Locations of LLNL Livermore Site and Site 300.
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UCRL-AR-J2406J
Final ROD for the GSA Operable Unit, Site 300
1997
Site 300 boundary
Legend
General Services
Area Operable Unit
Road
Scale: Feet
0 2000 4000
General Services
Area Operable
Unit
ERO-GSA-ROO-0002
Figure 2. Location of the General Services Area OU at LLNL Site 300.
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t
Legend
'Fault; arrows show
relative sense of
vertical offset
Water Table
Qt-Tnsc1
hydro-
geologic
unft
Sewage treatment
pond Water
Qal-Tmss
hydrogeologic unit
Low permeability
sedimentary rock
(Tmss)
c:
§
50
§
l
Co
5?'
Not to scale
EHD-QSA-ROO-0003
Rgure 3. Conceptual hydrogeologic model of the General Services Area.
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'•"" 871.-
\
Steam-cleaning/
sink facility
\
' x - Corp i
'/ ..••'•' yard j
/ /_A storage!
874
Decommissioned ;'-•-""'—IT""""""
solvent drum rack /,'•'''.'•• ^r :
and solvent /''/' Sewage
retention tank ..-// j treatment
/ pond '.;.-•"""
Former dry wells
Scale : feet
0 125 250
§
i
ERO-GSA-flOO-OCXM
Figure 4. Confirmed chemical release sites in the central GSA.
-------
UCRL-AR-I24061
Final ROD for the GSA Operable Unit. Site 300
1997
Scale : feet
0 125 250
Site 300
Site 300
boundary
I'.-
Debris burial
trench
Debris burial
trench area
I//
// .
*• ••• /
/:<••
Connolly
Ranch
-California Department
of Forestry
Corral ^
ERO-GSA-ROO-0005
Sewage
treatment
pond
Figure 5. Confirmed chemical release sites in the eastern GSA.
-------
.rJtTW-875-08
*V . .-• Drv
Dry
W-875-09
Dry
Scale : feet
0 25 50
S«wtg* treatment pond
Inset map of dry well pad wells
W-35A-08
<0.5
W-35A-14
<0.5
ERO-GSA-ROO-0006
OillO-2
Legend
-•V- Monitor well completed In the Qt-Tnsc,
hydrogeologic unit with TCE
concentration In i
oaiio-2
Inactive water-supply well
Inferred ground water TCE
isoconcentration contour (ng/L), dashed
where uncertain, queried where unknown
Scale : feet
0 100 200
s
if
£
2
I
Figure 6. TCE concentrations in ground water from the shallow aquifer (Qt-Tnsc,) in the central GSA (4th quarter 1995 data).
-------
-4- W-7C
ERCM3SA-ROO-OOU
Figure 7. TCE concentrations in ground water from the Tnbs1 regional aquifer in the central GSA (4th quarter 1995 data).
-------
7.1
legend
Monitor well computed to (iluvtaVshaUm
bedrock equder ihoielngioul VOC
concentration (yoAJ
-•- Monitor well completed In the deiper
•KOMI bedrock equtfer thowMg total VOC
(<•>) concentration bioA.).O«a not used In
conlourlno.
Tool VOC concdMnilon contour
OiyLK da*n*d ntxr* uncwuln,
qtMrtod «rtt«f* unknown
I
I
Flgun S. ToUl VOC conc.nl/itlont In ground w*Ur In lh« tlluvluni (Qtl) -ind tUllow bMlroek (Tnb»,) In th» «ajtern CSA (4th qjartor §
199SHIU). I ~J
-------
Legend
Monitor well completed in the Tntas,
hydrogeologlc unit (regional aquifer)
with TCE concentration In ug/L
Active water-supply well
Inactive water-supply well
Inferred ground water TCE
isoconcentratlon contour (fig/L), dashed
where uncertain, queried where unknown
1.5
W-26R-07
\ 18
W-26R-01
\\
<0.5
W-26R-02
Sewage trealmenl pond
<0.5
W-25N-10
W-25N-13
<0.5
I
I
>3
§
I
t
I
Ccllfoml* Department
of Forestry Fir*
Department
<0.5
W-25N-25
ERD-GSA-ROD-0009
Figure 9. TCE concentrations in ground water from the deeper Tnbs1 regional aquifer in the eastern GSA (4th quarter 1995 data)
-------
UCRL-AR-12406I
Final ROD for the GSA Operable Unit, Site 300
1997
Base from U.S. Geological Survey.
Midway 7.5' quadrangle, 1953, photorevised, 1980.
Tracy 7.5' quadrangle. 1954, photoreviaed, 1981.
2/5
1 MILE
ERD-GSA-R OO-O010
Scale
Legend
CDF-1 "4" Active water-supply well
—-—— Site 300 property boundary
Ground surface elevation
C 900 1ft above MSL)
Contour Interval: 100 ft
Figure 10. Locations of active water-supply wells.
-------
VCM^Ut-IHMI
final KODforttu CM O>» mMr (/«/( fil, JOfl
Ugand
: bdtUng wall lo ba uaad lor
alluvial aqulfM ground watar
attraction. Wall W-I76-OI
alto lo ta* uMd lo aitracl
aoll vapor.
W.Jf •$•* EiliUng mil lo b* HMd lor
Tnlii, r»fllon
-------
r-
i.
+
O
24
Legend
eoinpM
bedrock equMer showing lotslVOC
Monitor well completed In the de«p«f
beilroi*.*^ snowing tot* VOC
canoMlrallenbignj.O«t«noluMdln
«£
^
/
Aettv««nMr-«upply«nU
Spring
TOM VOC eofmntntlon contour
tiiQAJ, Omn*S ohtra uncvtaln,
quwtod wtor* unknown
Seal*: !••!
0 290 500
pond
§
|
CalHomU DopuUMM ot Fonwliy
Rgur* 12. Total VOC concentrations In ground inter In th* •lluvlum (Oil) and •hallow bedrock (Tnb«,) In the ••stem GSA (4th quartor
1991 data).
-------
<0.5
W-TD
COM
CON-2
Legend
Monitor well completed In the Tnbsj
hydrogeologlc unit (regional aquifer)
with TCE concentration In ng/L
Active water-supply well
Inactive water-supply well
Inferred ground water TCE
Isoconcentratlon contour (ng/L), dashed
where uncertain, queried where unknown
15
W-26R-07
\ 71
W-26R-01
\\
<0.5
W-26H-02
W-TD A_
' <0.5 ,,
W-26N-10 »-W-2SN-11
W-25N-13 <0.5
<0.5 r—I
to -*-
-------
Water treatment
(Aqueous phase GAC)
Discharge
of treated
ground water
to Corral
Hollow Creek
Extracted
ground water
Ground water
extraction well*
§
g
f
i.
Ui
§
CRO-OM-AQO-OOtt
Figure 14. Schematic of the eastern GSA remediation system for the selected remedy (Alternative 3b).
-------
Approx. local
of dry t
875-S1, 87
Inset map of dry well pad wells
I
W-873-02
22
<0.5+
W-35A-02
ERD-QSA-ROtMMU
Gallo-2
w"70
« .. ,
Gallo-2
/
Legend
Monitor well completed in the Qt-Tnsc,
hydrogeologlc unit with TCE
concentration In jig/L
i- Inactive water-supply well
Inferred ground water TCE
isoconcentratlon contour (ng/L), dashed
where uncertain, queried where unknown
Note: Data shown for Building 875 dry
wells Is for 1st quarter 1992
Scale : feet
o 100 200
§
>
3-
<»
§
f
I
to
Figure 15. TCE concentrations in ground water from the shallow aquifer (Qt-Tnsc^ In the central GSA (4th quarter 1991 data)
58
-------
Legend
i w 7C Monitor well completed
< 0.5
m
Tnbs, hydrogeologlc
unit with TCE
concentration In ng/L.
Data in parenthesis (<0.5)
not used In contouring.
Inferred ground water
TCE isoconcentration
contour (tig/L), dashed
where uncertain, queried
where unknown.
Scale : feet
o 100 200
Jo
§
1
o-
s-
§
ERD-GSA.ROD-0007
Figure 16. TCE concentrations in ground water from the Tnbs1 regional aquifer in the central GSA (4th quarter 1991 data).
-------
Vapor treatment (GAC)*
Discharge of
treated vapor
vapor from
air stripper
Discharge
of treated
ground water to
ground surface
Vapor treatment (GAC)
Water
treatment
(air stripper
oraqueous*
phase GAC)
Extracted
soil vapor
Vacuum pump , •
around water and soil
vapor extraction wtdls
Extracted
ground water
Ground water
extraction well
Ciaystofteaquftard
c:
Q
r-
i.
5
5"
i
I
Treatment of vapor from ground water treatment system Is not necessary if aqueous-phase GAC is used.
ERD-OU.ROO-OOt)
Figure 17. Schematic of the central GSA remediation system for the selected remedy (Alternative 3b).
-------
Tables
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 1. Contaminants of potential concern in ground water in the GSA.
Contaminant
Central GSA
1,1,1-trichloroe thane
1,1 -dichloroethylene
cis-l,2-dichloroethylenec
Acetone
Benzene
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Trichlorofluoromethane (Freon 113)
Eastern GSA
1,1,1-trichloroe thane
1,1 -dichloroethylene
l,2-dichloroethylenec
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Maximum
concentration9
2.0 x 103
4.0 x 103
1.0 x 103
8.2 x 10°
5.0 x 10ld
3.3 x 10°
7.4 x 10°
2.5 x 104
2.4 x 10s
1.6 x 102
9.4 x 101
5.0 x KT1
6.0 x 10-1
3.3 x 10°
1.4 x 101
4.4 x 10°
6.1 x 101
Mean
concentration*'''
2.93 x ItT1
7.37 x KT1
2.56 x 10°
4.08 x 10°
4.05 x 1(T2
6.10 x 10-1
3.89 x 101
8.30 x 102
1.07 x 101
2.93 x KT1
4.30 x KT1
4.27 xHT1
4.05 x 10~2
9.60 x 10-1
1.32 x 10°
2.66 x 101
95% UCLa
1.62 x 10°
1.18 x 10°
3.75 x 10°
5.78 x 10°
6.62 x lO-2
8.98 x lO"1
7.73 x 101
3.09 x 103
1.89 x 101
1.62 x 10°
4.45 x ID"1
4.41 x ir1
6.62 x ID*2
4.25 x 10°
1.64 x 10°
3.39 x 101
a All units are in Mg/L.
" Estimate of the arithmetic mean of the underlying log normal distribution.
c The chemical 1,2-dichloroethylene (1,2-DCE) exists as two isomers, cis-l,2-DCE and trans-l,2-DCE. At various
times throughout the nine years of ground water analysis at Site 300, this chemical has been analyzed for as
1,2-DCE (total), as one or both of the specific isomers, or as all three. When concentration data were available
for one or both isomers, we used those values and omitted the less specific analysis for total 1,2-DCE from
further consideration. The exceptions to this were in cases where the concentration reported for total 1,2-DCE
was greater than that reported for one or both isomers.
" The value given for benzene is the maximum measured concentration for this chemical in ground water in the
central GSA. This maxima was reported from the last quarter of sampling data included in the SWRI database
(first quarter, 1992) (Webster-Scholton, 1994), and came from the vicinity of the Building 875 former dry wells.
A mean concentration and a 95% Upper Confidence Limit (UCL) were not calculated.
1/97/12406 l:GSAROD:rtd
T-l
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 2. Contaminants of potential concern in surface soil (<0.5 ft) in the GSA.
Contaminant
1,1,1-trichIoroethane
Acetone
Cadmium
Chloroform
Copper
HMX
Tetrachloroethylene
Toluene
Trichloroethylene
Trichlorofluoromethane (Freon 113)
Trichlorotrifluoroethane (Freon 11)
Xylenes (total isomers)
Zinc
Maximum
concentration9
5.0 x 10~3
6.0 x NT2
1.6 xlO1
3.0 x ID"4
3.4 x 102
2.0 x NT2
S.OxlO-2
6.0 x 10~3
8.4 x 10~2
1.3 x 10~2
7.9 xlO-2
7.0 xlO-3
8.3 x 102
Mean
concentration*'*'
6.85 x 10-4
3 39 x 10~2
6.43 x 10°
3.82 x 10"4
3.94 x 101
NAC
1.61 x 10~3
1.30 x 10~3
3.75 x 1CT3
1.00 x 10~3
1.23 x 1(T2
1.47 x 10~3
2.06 x 102
95% UCLa
1.86 x l
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
January
Table 3. Contaminants of potential concern in subsurface soil (>0.5-12.0 ft) in the GSA.
Operable unit
region
Building 875
Debris burial
trenches
Contaminant
1,1,1-trichloroethane
1,1-dichloroethylene
cis-l,2-dichloroethylene
Chloroform
Tetrachloroethylene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 11)
Chloroform
Methylene chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Trichlorofluoromethane
(Freon 113)
Trichlorotrifluoroethane
(Freon 11)
Maximum
concentration9
1.0 x Iff"2
5.0 x NT4
3.0 x 10-4
3.0 x 10-4
1.0 x 10-1
5.4 x 10-1
6.0 x ID"2
4J x ID-2
1.4 x 10-2
8.8 X lO-3
5.0 x 10~3
2.4 x 10-2
3 .3 X lO-3
4.0 x 10-4
Mean
concentration3'**
2.13 x 10~3
NCC
1.88 x ID"4
1.88 x 10-*
3.28 x 10~2
1.74 x ID"1
8.03 x ID"3
1.47 x ID"3
4.26 x KT4
1.95 x 10-3
2.73 x 1C-3
2.43 x ID-3
1.34 x 10-4
1.20 x 10-4
95% UCLa
4.38 x 10-3
5.0 x 10-*c
2.96 X lO"4
2.96 x Itr4
7.54 x ID"2
4.14 x 10-1
1.87 x ID"2
3.35 x ID-3
1.74 X ID"3
4.32 X ID"3
3.14 x ID"3
4.31 x ID"3
3.95 X ID"4
1.67 X 10-4
a Units are mg/kg.
" Estimate of the arithmetic mean of the underlying log normal distribution.
c NC = Not calculated. For certain data sets, calculation of a UCL yielded a value greater than the
maximum measured concentration (Webster-Scholten, 1994, Appendix P). In those instances, a mean
concentration was not calculated, and the maximum concentration is given instead of a UCL.
1/97/124061 :GSA ROD:rtd
T-3
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 4. Contaminants of potential concern in VOC soil flux in the GSA.
Contaminant
Central GSA
1,2,4-trimethylbenzene
1,3,5-trimethylbenzene
Benzene
Methylene chloride
Toluene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Eastern GSA
1,1/1-trichloroe thane
1,2,4-trichlorobenzene
Dichlorodifluoromethane
(Freon 12)
Methylene chloride
Styrene
Toluene
Trichloroethylene
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Building 875 dry well area
1,2,4-trimethylbenzene
Chloromethane
Dichlorodifluoromethane
(Freon 12)
Ethylbenzene
Methylene chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Limit
of detection
(mg/m2*s)
1.05 x 10-*
1.10 x 10-*
6.79 x 10~7
9.50 x 1(T7
8.01 x 1(T7
1.13 x KT6
1.70 x 10"6
9.58 x ID"7
9.58 x 10-7
1.18 x 10-6
1.09 x 10-*
1.09 x 10-6
8.67 xlO-7
9.07 xl(T7
8.34 x 10~7
1.18 x 10-6
1.77 x 10~5
9.98 x 10~7
9.98 x 1(T7
1.09 x lO"6
4.63 x l
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 4. (Continued)
Contaminant
Building 875 dry well area
(Continued)
Trichlorotrifluoroethane
(Freon 113)
m- and p-xylenes
o-xylenes
Limit
of detection
(mg/m2»s)
1.82 x KT6
9.98 x Itr7
9.98 x l
-------
Final ROD for ike CM Operable Vnlt, Site MO
January 1997
PtfUrt (flitene) fat; CMftvrfwuw hoof If ntutftrnM all fartltlei
ri.«- —1..-.--1 - -
MI..M«..(.) Confld.nc.Umll conc.nlr.Hoiu
i «n*t pamftff
D.U mduiled >m from mirf.c* Mill iample« Mau-Ioading (Anipaugh .1.1,1975).
coliKted throughout th« OU
1,1,1-trichloro.lhaiw
Action.
Cadmium
Chloroform
Kmgftg*
O0003 mg/kg*
«dlKtadaraagh*
UlxlO-'mg/m1*
9JImg«g*
O000873 mg/kg*
SCJmgftg*
WBmgAg*
OAnsSmg/kg*
OJXQSCmg/kg*
04118 rag/kg*
000219 mg/kg*
00384 mg/kg*
0X1034 mg/kg*
362 mg/kg*
OODUCmg/kg* LWx 10-* mg/kg*
0049mg«g* 4^xlO->mg/kg*
9 Jl mg/kg* 9JlxlO°mg/kg*
0000675 mg/kg* 8.75 X 10~* mg/kg*
56J mg/kg* S47X101 mg/kg*
O02mg/kg* iJOO x 10-1 mg/kg*
000358 mg/kg* 3.58 xlO-1 mg/kg*
oomacmgflig* racxio^mgflig*
OOllBmg/kg* U*xUT*mg/kg*
00019 mg/kg*
0X081 mg/kg*
00034 mg/kg*
T-6
3J4xlO-* mg/kg*
3^0x10-* mg/kg*
3«x«r»mgfl(g*
-------
UCKL-AX-IH062
Table S. (Continued)
Final HOD for the GSA Operable Unit. Site 300
Media/process
release area(s)
Model and/or method
Potential eiposure polnt(s)
Chemicals of concern
Maximum
concentration at
release areafs)
95% Upper
Confidence Limit
January 1991
Estimated exposure-
point
concentrations
VtlatUivUion of contaminant! from lukiurfoc* toil Into air wilk'ui a building
Immediate vicinity of Building 875.
Volatilization of contaminants from
subsurface soil and diffusion of VOCs
through concrete Into a building. VOCs
(McKonel992).
Inside Building 875
1,1-dlchloroelhylene
l.M-trichooroe thane
Benzene
Chloroform
cls-U-diehloroethylene
Mithylene chloride
Tetrachlonethylene
Trichloroethylene
Trlchlorofluoromethane
(Freonll)
Trlchlorotrifluoroethane
(FreonlU)
0X005 mg/kg*
OOlmg/kg'
OXOSmg/kgC
0X032 tag/kg*
OXlmg/kg*
00013 mg/kg«
aiing/kg*
0.75mg/kg<
0X016 mg/kg<
OX«mgftg<
OOOOlUmg/kg*
000286 mgftg<
0000917 mg/kg*
0X0199 mg/kg<
0X0317 mg/kg<
0000612 mg/kg<
0X697 mg/kg1
0596mg/kg<
0X016 Dig/kg*
0X209 Big/kg'
2J9xlO-«mj/m3b
L23xlO-*mg/mIb
169x10-* mg/orlb
5.71xl(r5mg/m5b
3^2xlO-»mg/mJb
I55xl0-*mgtalb
1.10xlO-» mg/mjl>
UaxlO-Jmg/m»'
2J3xlO-tmg/m3b
5.63 x 10-> mg/m3b
fr '—"=[—'~ -frrir' — *i — t/Tii r-frr/ — "" ** **" -*— p*—
Potential releases la the vldnlly of the debris
buial trench.
— — -
feafociurffnuiufiMi
«s>imi
Ur (Central GSA)
Building 875 dry well area, solvent drum rack
area. Building 879 steam cleaning/sink area.
Volatilization of contaminants from soil to
air (Hwang et al, 1986); air dispersion
(Tomer, 19J2).
. . • • •
^** — •* •
Wilson and Miller (1978) mathematical
ground water model.
Building 872 dry well. Building 874 dry well.
Building 873 dry well considered it a tingle
release.
In the vidnlty of the debris burial trench.
Ground water from the Qt-Tnsci
hydrogeologlc unit. Assumes undiluted
transport of VOCs from Building 875 area
to the Site 300 boundary. Model Is used to
simulate the transport of TCE through the
alluvium to well CDF-1.
Chloroform
Methylene chloride
Tetradudocoethyiene
Toluene
Trichloroethyiene
Trichlorofluoromethane
(Freonll)
Trichlorotriflaoroethane
(FrwnlU)
Primarily
trlchloroethylene;
co-conlamlnants detected
In ground water samples In
the study area also
considered.
OJOOmsfktf
Oj014mg/kg<
00068 mg/kg<
OXOSmgykg<
0X024 mg*g<
0X033 mg/kg«
a0004mg/kg<
240X00 jlg/L«d
0X0335 mg/kg*
0X0174 mg/kg*
0X0432 rngfltg1
0X0314 mgft*/
OXObtnng/kg1
0X00395 ing/kg*
0X00167 mg/kg<
35^40 (uj/L* at site
boundary
Assumed
modeling source
term Is 1X00 flg/L
U5xlO-*mg/Bin>
«J3xlO-»«»/m*
lUxlO-^Bij/or*
UlxlO->ngnan>
L24xlO-»mg/nr">
7Xlxl(TsmgAnsb
$J3 x MT* mgAn^b
35^49 ugrt.^
SJSjig/L4^
T-7
-------
1:
UCRL-M-114062
Tables. (Continued)
Final KOD/onht GSA Opttabk Unit, Silt 300
January 1997
Medla/pnxee*
relea** araa<»)
Modal and/or method
Potential expomir* polntit)
Chemluli of concern
Maximum Estimated expoeur*-
concentration at 95% Upper point
release area(a) Confidence Limit concentration*
StUfntk «WfraW m*r (Bourn GSA)
Oebrii burial trenches.
PLUME analytical ground water model.
Available data throughout the OU conaidered FS, Section 15J (Ruelh and Beery, 1995)
(Section LU).
Alluvial ground water. Assumes transport Primarily
of VOC* from release alle to the Site 300 Mddomthrlene;
boundary and CDF area. Modal Is used to co-contaminant* detected
almulate the transport of TCE through the In ground water (ample* In
alluvium to aheep ranch well SR-1. the study are also
considered.
General area of OU and vicinity of debris Primarily TCE, PCE.
burial trenches. (Exposure pathway*
discussed In Section 15J of the FS)
aug/lTCE"!
modeling (oarc*
FS, Section tSJ. FS, Section 1JJ. FS, Section 1JJ.
Surface aolL
Ali.
rndkted auxboiui 70-vear average TCB coot.ntr.don and «|>o>ure?a|jit toix.nlr.llon at the Site MO boundary.
Predicted i-r-*~"~ TD-yeat avenge TCB cont.ntr.aon and me eipoenre-peuit cont.ntr.tlon In ground water pumped (ram CDF-I.
Predicted maxtmua 70-year average TCB concentration and the estimated eipowre-polnl concentration In ground water at the eastern CS A (awurnlng no plume commingling).
I •uxtaua TD-year averafe TCE concentration and eetlauled eiposure-polnt comentralim at well SR-1.
Noleo
mlOfnai per nbk metu;
•dcncm per Ulei.
T-8
-------
Table 6. Cancer risk and hazard index summary, and reference list for the GSA OU.
Potential
exposure pathway
Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the Building 875 dry well area in the central GSA
(AOS exposure)
Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the central GSA (AOS exposure)
Inhalation of VOCs that volatilize from soil to outdoor air in the
vicinity of the eastern GSA (AOS exposure)
Inhalation of VOCs that volatilize from subsurface soil into the
indoor air of Building 875 in the central GSA (AOS exposure)
Potential AOS exposure to contaminants in surface soil (0 to
0.5 ft) in the GSA for:
a) inhalation of particulates resuspended from surface soil, and
b) ingestion and dermal adsorption to surface soil
Additive incremental
excess lifetime Additive
cancer risk estimate hazard index
2 x 1(T7 6.2 x 10~3
7 x 1(T7 1.2 x 10~3
2 x 10~7 1.3 x 10~3
1 x 10~5 3.0 x 10-1
a) 2 X ID"7 a) 5 6 x 10-5
b) 2 x 1(T10 b) 8.5 x 1(T3
References for related tables
in supporting documents
FS:
Tables 1-28
1-31
1-34
FS:
Tables 1-29
1-32
1-35
FS:
Tables 1-30
1-33
1-36
SWRI (Chapter 6):
Table 6-51
Appendix P
Tables P-27-6.1
P-27-6.10
FS:
Table 1-25
SWRI (Appendix P):
Tables P-27-6
a) P-27-6.11
b) P-27-6.12
1
r-
1
5
!
o
§
*»
Ci
B
t
1
5"
c:
a
£
1
-------
Table 6. (Continued)
Potential
exposure pathway
Adult Onsite Exposure in the GSA
Potential residential exposure to contaminated ground water
that originates in the GSA at:
a) Central GSA site boundary
b) Eastern GSA site boundary
c) Well CDF-1
d) Well SR-1
•
Additive incremental
excess lifetime
cancer risk estimate
9xlO~7
a) 7xl(T2
b) 5xl(T5
c)lxlO~5
d) 2 x 10~5
Additive
hazard index
9.8 x HP3
a) 5.6 x 102
b) 5.0 x 10-1
c) 1.4 x 10-1
d) 1.6 x 10"1
Location of related tables in
supporting documents
FS:
Table 1-37
SWRI (Chapter 6):
Table 6-55
FS:
Table 1-26
SWRI (Appendix P):
Tables P-27-6.5
P-27-6.6
P-27-6.7
P-27-6.8
P-27-6.13
P-27-6.14
P-27-6.15
P-27-6.16
Notes:
AOS = Adult Onsite.
FS = Final Feasibility Study for the General Services Area, LLNL Site 300 (Rueth and Berry, 1995).
GSA = General Services Area.
SWRI = Final Site-Wide Remedial Investigation Report, LLNL Site 300 (Webster-Scholten, 1994).
VOC = Volatile Organic Compound.
§
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I
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'
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UCRL-AR-124061
Final ROD for the CSA Operable Unit, Site 300
January 1997
Table 7. Summary of GSA OU remedial alternatives.
Alternative 1: No action
Alternative!: Exposure
control
Alternative 3a: Remediation
and protection of the Tnbsj
regional aquifer
• Monitoring
— Quarterly water level measurements of monitor wells and
supply wells.
— Periodic ground water sampling and analysis of monitor wells
and supply wells.
— QA/QC samples.
• Administrative controls
— Fencing and warning signs around site.
— Full-time security guards on site.
• Continued ecological surveys.
• Other
— Well and pump maintenance.
— Reporting.
— Project management.
— Database management
— QA/QC review.
Modeled project life: 80 years of ground water monitoring to reach
MCLs.
All elements of Alternative 1 plus:
• Contingency POU treatment
— Install and operate POU GAC treatment system for offsite water-
supply wells CDF-1, CON-1, and SR-1 if VOC concentrations
exceed MCLs.
Modeled project life: 80 years of ground water monitoring to reach
MCLs.
AH elements of Alternative 2 plus:
• Ground water extraction well installation
— Install four new ground water extraction wells.
— Convert six existing monitor wells to ground water extraction
wells and one to an injection well.
• Ground water extraction and treatment
— Extract ground water from 20 extraction wells (19 shallow
alluvial, 1 Tnbsi regional) and reinject into 1 well (Tnbsi
regional).
— Install new ground water treatment systems using air stripping,
VOC adsorption, and/or other appropriate technologies.
Design capacity would be approximately 15+ gpm at the central
GSA and 46-t- gpm at the eastern GSA.
— Extract ground water from Tnbsi regional aquifer until VOC
concentrations reach MCLs.
— Extract ground water from the alluvial aquifer until ground
water VOC concentrations are reduced to levels protective of
the Tnbsi regional aquifer (approximately 100
1-97/124061 :GSAROD:rtd
T-ll
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 7. (Continued)
• Soil vapor extraction (SVE) and treatment
— SVE from seven existing wells.
— SVE and treatment using existing system until vapor
concentrations reach levels that prevent recontamination of
ground water above MCLs, and to reduce inhalation risk in
Building 875.
• Other
— Permitting.
— Ground water treatment system and SVE system maintenance.
Project life: 10 years of SVE, 10 years of ground water extraction and
treatment at the eastern GSA and 30 years at the central GSA, and
70 years of ground water monitoring to reach MCLs.
Alternative 3b: Ground
water plume remediation
All elements of Alternative 3a plus:
• Continued ground water extraction and treatment at the central
GSA until ground water VOC concentrations are reduced to MCLs.
Project life: 10 years of SVE, 10 years of ground water extraction and
treatment at the eastern GSA and 55 years at the central GSA, and
60 years of ground water monitoring to reach MCLs.
l-97/12406l:GSAROD:nd
T-12
-------
Table 8. Comparative evaluation of remedial alternatives for the GSA OU.
Alternative
Alternative 1
No action
Overall protection
of human health and
environment
Human health:
No
Environment: No
Compliance
with ARARs
Criterion may
be metc
Short-term
effectiveness
Protective of site workers
and the community during
monitoring by preventing
potential exposure through
the use of administrative
controls and/or use of
protective equipment.
Ground water and air risks
not addressed.
Long-term
effectiveness and
permanence
Not effective.
Reduction in
contaminant volume,
toxicity, and mobility
Dependent on
natural attenuation
and degradation.
Implementability
Implementable
Costa-b
3.47
I
E
so
Alternative 2
Exposure
control
Human health:
Air No
Ground water
Yesd
Environment: No
Criterion may
be metc
Alternative 3a Human health:
Remediation Air Yes
and Ground water Yes
protection of
the regional Environment: Yes
aquifer
Criterion may
be met
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment
Addresses ground water
risk with POU treatment at
existing water-supply
wells. Does not address air
risk.
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment
Addresses site risks with
active remediation of soil
and ground water.
Effective for ground
water risks at existing
water-supply wells.
Not effective for long-
term reduction of VOC
mass or air risk.
Dependent on
natural attenuation
and degradation.
Implementable 3.69
1
•§
f
?'
J/J
«r
1
Effective for air and
ground water risks in
the Tnbsi aquifer.
May not be effective for
ground water risk in
shallow aquifer in the
central GSA.
Ground water and soil
vapor extraction
increases source
removal effectiveness.
Reduction in shallow
unsaturated zone,
and shallow and deep
Implementable 17.17
contamination;
partially dependent
on natural
attenuation and
degradation.
-------
Tables. (Continued)
Alternative
Alternative
3b
Ground water
and soil
remediation
of both
shallow and
regional
aquifers
Overall protection
of human health and Compliance
environment with ARARs
Human health: Criterion met
Air Yes
Ground water Yes
Environment: Yes
Short-term
effectiveness
Protective of site workers
and the community during
remedial action by
preventing potential
exposure through the use of
administrative controls
and/or use of protective
equipment.
Addresses site risks with
active remediation of soil
and ground water.
Long-term
effectiveness and
permanence
Effective for air and
ground water risks.
Ground water and soil
vapor extraction
address all soil and
ground water
contamination.
Reduction in
contaminant volume,
toxicity, and mobility Implementability
Reduction in shallow Implementable
unsaturated zone,
and shallow and deep
aquifer
contamination.
Costa-b
18.90
Estimated tola] present worth in millions of 1995 dollars. Overall cost is highly dependent on the required length of pumping time.
The estimated costs for all alternatives presented in this ROD are slightly lower than the costs presented in the GSA FS and PP. This is due to modifications to the
1) contingency POU treatment component based on negotiations with the well owner, and 2) ground water monitoring component based on changes made to the eastern and
central GSA treatment facility permit monitoring program requirements.
Relies solely on natural attenuation and degradation to comply with Safe Drinking Water Act, Basin Plan, and State Resolutions 68-16 and 92-49.
Protective of human health for ingestion of ground water from existing water-supply wells.
I
g
I
Jo
ST
I
58
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Table 9. Chemical-specific ARARs for potential chemicals of concern in ground water at the
GSA OU.
Chemical of concern
1,1,1-trichloroethane
1,1-dichloroethylene
cis-l,2-dichloroethylene
Benzene
Bromodichloromethane
Chloroform
Tetrachloroethylene
Trichloroethylene
Cancer
group"
D
C
D
A
B2
B2
B2-C
B2-C
Federal MCL
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. Selected remedy (Alternative 3b): Capital costs for source mass removal and
plume migration prevention in the GSA OU.
Unit price Total
Quantity Unit type (1995$) (1995$)
Capital costs
Central GSA
Ground water and soil vapor extraction system major
equipment costs (MEC)
Wellhead vaults, valves, sampling ports, gauges
Additional wellhead vaults, valves, sampling ports,
gauges
Electrical line and conduit
2-in. polyvinyl chloride (PVC) piping
Electric submersible pumps (1 /2 horse power [hp])
Additional electric submersible pumps (1/2 hp)
PVC pipe fittings, unistrut
SVE blower system (5 hp)
SVE pitot tubes, vacuum gauges, sampling ports
7 previously installed
10 each 1,500 15,000
1,200 foot 1.75 2,100
1,200 foot 1.50 1,800
10 previously installed
10 each 800 8,000
1 lot 10,000 10,000
1 each 2,000 2,000
Previously installed
SVE treatment MEC
Moisture accumulation assembly, carbon canister
hookup
Vapor-phase carbon canisters (1,000 Ib)
SVE manifold, piping
Previously installed
3 each
Previously installed
6,000 18,000
Ground water treatment MEC
Particulate filter assembly
Low-profile tray air stripper (includes blower and
transfer pumps, total of 7 hp)
Carbon dioxide injection equipment
Discharge storage tank (20,000 gal.)
Discharge pump (15 hp)
Moisture accumulation assembly, carbon canister
hookup
Air heater (700 W)
Vapor-phase carbon canisters (140 Ib)
Manifold, piping, valves, gauges, sampling ports,
totalizer, controllers
Discharge piping and fittings
1 each
1 each
1 each
Previously installed
Previously installed
1 each
1 each
Previously installed
1 lot
Previously installed
3,700 3,700
20,000 20,000
1,500 1,500
1,100 1,100
500 500
15,000 15,000
T-16
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit. Site 300
January 1997
Table 10. (Continued)
Unit price Total
Quantity Unit type (1995$) (1995$)
Eastern GSA
Ground water extraction and treatment system MEC
Wellhead vaults, valves, sampling ports, gauges
Electrical line and conduit
Electric submersible pumps (1/2 hp)
2-in. PVC piping
PVC pipe fittings, unistrut
Particulate filter assembly
Low-profile tray air stripper (includes blower and
transfer pumps, total of 7 hp)
Moisture accumulation assembly, carbon canister
hookup
Vapor-phase carbon canisters (140 Ib)
Manifold, piping, valves, gauges, sampling ports,
totalizer, controllers
Discharge piping and fittings
Total MEC for eastern GSA ground water treatment
system
Total MEC for GSA ground water extraction and SVE
treatment systems
Electrical components (20% of MEC)
Installation cost (58% of MEC)
Major equipment installed cost (MEIC)
Other capital costs
Wells/borings
Ground water extraction well installation and
development
Piezometer installation and development
Soil boring and initial water sample analyses
Soil disposal (Class III)
Hydraulic test for ground water extraction wells
Hydraulic test for reinjection well
Hydraulic test for piezometers
Structures
3 previously installed
Previously installed
3 previously installed
Previously installed
Previously installed
1 each
1 each
1 each
Previously installed
Previously installed
Previously installed
3,700
20,000
1,100
3,700
20,000
1,100
24,800
123,500
24,700
71,630
219,830
4
10
14
35
10
1
10
well
well
well
cuyard
well
well
well
10,000
10,000
1,500
20
3,000
5,000
1,500
40,000
100,000
21,000
700
30,000
5,000
15,000
T-17
-------
UCRL-AR-124061
Final ROD for the CSA Operable Unit. Site 300
January 1997
Table 10. (Continued)
Quantity
Equipment building for central GSA SVE treatment
system 1
Equipment building for central GSA ground water
treatment system 1
Equipment building for eastern GSA ground water
treatment system 1
Geotechnical testing 3
Contingency POU ground water treatment system for
off site water-supply wells CDF-1, CO AM, and SR-1
Wellhead modification 3
Particulate filter 3
Aqueous-phase carbon beds (1,000 Ib) 6
Double-containment skid (81 x 15') 3
System plumbing, totalizer, fittings 3
Total field costs (TFC)
Professional environmental services
Design/assist with project management
Permitting
Start-up labor and analyses
SVE performance evaluation
Total professional environmental services
Unit type
each
each
each
each
each
each
each
each
lot
Unit price
(1995 $)
300,000
300,000
300,000
20,000
1,000
2,000
6,000
4,000
2,000
Total
(1995 $)
300,000
300,000
300,000
60,000
3,000
6,000
36,000
12,000
6,000
1,454,530
50,000
50,000
60,000
25,000
185,000
LLNL tax (11% of total field costs and professional
environmental services)
LLNL Environmental Restoration Division (ERD)
team
Full-time employee (Fit)
Remedial Design Report
Total LLNL ERD team
FTE
180,000
180,348
540,000
300,000
840,000
T-18
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. (Continued)
Unit price
Quantity Unit type (1995 $)
LLNL technical support services
LLNL Plant Engineering planning and Title I, II, and III
services
Total LLNL support services
Total capital costs
5
Operation and maintenance (O&M)
Fixed O&M costs for soil vapor and ground
Fixed annual O&M costs for SVE
Electricity
Electrical capacity charge
SVE air sampling analysis
Maintenance materials (10% of total installed MEG)
LLNL tax (11% of outside charges)
Project management
System optimization, engineer
Well field optimization, hydrogeologist
Operating labor
Clerical
Maintenance labor (15% of total installation cost)
Total fixed annual SVE O&M costs
Total present worth of fixed O&M for soil vapor
extraction, years 1-10 (factor = 8.317)
Fixed annual ground water extraction and treatment
O&M for central GSA
FTE
costs
water extraction and
30,000
3.7
12
0.15
0.20
0.10
0.30
0.10
Electricity 170,000
Electrical capacity charge
Scale prevention/recarbonation
Ground water treatment system air sampling analysis
Ground water treatment system analyses (water only)
Maintenance materials (10% of total installed MEC)
LLNL tax (11% of outside charges)
Project management
System optimization, engineer
21.6
4,000
12
12
0.10
0.15
kw»h
kw
event
FTE
FTE
FTE
FTE
FTE
kw»h
kw
lbCO2
event
event
FTE
FTE
180,000
treatment
0.07
36
560
238,500
173,500
173,500
129,800
92,600
0.07
36
0.60
560
200
238,500
173,500
Total
(1995$)
900,000
900,000
3,559,878
2,100
133
6,720
8,200
1,887
35,775
34,700
17,350
38,940
9,260
7,134
162,199
1,349,010
11,900
776
2,400
6,720
2,400
16,300
4,455
23,850
26,025
T-19
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. (Continued)
Well field optimization, hydrogeologist
Operating labor
Clerical
Maintenance labor (15% of total installation cost)
Total fixed annual ground water extraction and
treatment O&M for central GSA
Total present worth of annual ground water treatment
O&M for central GSA, years 1-55 (factor = 24.264)
Quantity
0.15
0.30
0.10
Unit type
FTE
FTE
FTE
Unit price
(1995 $)
173,500
129,800
92,600
Total
(1995$)
26,025
38,940
9,260
14,181
183,232
4,445,937
Fixed annual ground water extraction and treatment
O&M for eastern GSA
Electricity
Electrical capacity charge
Scale prevention /recarbonation
Ground water treatment system air sampling analysis
Ground water treatment system analyses (water only)
Maintenance materials (10% of total installed MEC)
LLNL tax (11% of outside charges)
Project management
System optimization, engineer
Well field optimization, hydrogeologist
Operating labor
Clerical
Maintenance labor (15% of total installation cost)
Total fixed annual ground water extraction and
treatment O&M for eastern GSA
Total present worth of annual ground water treatment
O&M for eastern GSA, years 1-10 (factor = 8.327)
60,000
7.6
12,000
12
12
0.10
0.15
0.15
0.30
0.10
kw»h
kw
lbCO2
event
event
FTE
FTE
FTE
FTE
FTE
0.07
36
0.60
560
200
238,500
173,500
173,500
129,800
92,600
4,200
274
7,200
6,720
2,400
10,000
3,387
23,850
26,025
26,025
38,940
9,260
8,700
166,981
1,390,453
Total present worth of fixed O&M costs for 55 years
7,185,400
T-20
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. (Continued)
Unit price Total
Quantity Unit type (1995$) (1995$)
Variable operating costs for soil vapor and
Annual costs, year 1
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 1
Total present worth, year 1 (factor = 0.966)
Annual costs, year 2
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 2
Total present worth, year 2 (factor = 0.934)
Annual costs, year 3
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 3
Total present worth, year 3 (factor = 0.902)
Annual costs, year 4
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, year 4
Total present worth, year 4 (factor = 0.871)
Annual costs, year 5
SVE replacement of GAC
Ground water treatment system replacement of vapor
GAC
Total annual costs, year 5
Total present worth, year 5 (factor = 0.842)
ground water extraction and treatment
3,950 Ib 2.30 9,085
650 Ib 2.30 1,495
10,580
10,220
980 Ib 2.30 2,254
650 Ib 2.30 1,495
3,749
3,502
490 Ib 2.30 1,127
650 Ib 2.30 1,495
2,622
2,365
125 Ib 2.30 288
650 Ib 2.30 1,495
1,783
1,553
60 Ib 2.30 138
650 Ib 2.30 1,495
1,633
1,375
Annual costs, years 6-20
T-21
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. (Continued)
SVE replacement of GAC
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 6-10
Total present worth, years 6-10 (factor = 3.801)
Annual costs, years 11-30
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 11-30
Total present worth, years 11-30 (factor = 10.075)
Annual costs, years 31-55
Ground water treatment system replacement of vapor
phase GAC
Total annual costs, years 31-55
Total present worth, years 31-55 (factor = 5.872)
Total present worth of variable operating costs for
soil vapor and ground water extraction and treatment
Ground water and soil
Annual costs, years 1-10
SVE vapor VOC analysis
VCX: analysis (EPA Method 601)
VCX: analysis (EPA Method 602)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Quarterly monitoring reports
LLNL tax (11% of outside charges)
Monthly SVE vapor sample collection
Quarterly water level measurements (including 10
piezometers)
Quarterly ground water sample collection
Semiannual ground water sample collection
Annual ground water sample collection
Annual spring water sample collection
Maintenance of ground water sampling system
Quantity
5
325
75
5
Unit type
Ib
Ib
Ib
Ib
Unit price
(1995 $)
2.30
2.30
2.30
2.30
Total
(1995 $)
12
748
759
2,885
173
173
1,738
12
12
68
23,705
vapor monitoring
84
206
12
3
4
7
111
7
89
12
3
101
each
each
each
suite
report
well
well
well
well
well
spring
well
110
50
50
545
15,000
375
62.50
500
250
125
125
430
9,240
10,300
600
1,635
2,178
60,000
9,235
2,625
6,938
3,500
22,250
1,500
375
43,430
T-22
-------
UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
Table 10. (Continued)
Project management
Total annual costs, years 1-10
Total present worth, years 1-10 years (factor = 8317)
Annual costs, years 11-55
VOC analysis (EPA Method 8010)
VOC analysis (EPA Method 8020)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Annual monitoring report
LLNL tax (11% of outside charges)
Quarterly water level measurements (including 10
piezometers)
Semiannual ground water sample collection
Annual ground water sample collection
Annual spring water sample collection
Maintenance of ground water sampling system
Project management
Total annual costs, years 11-55
Total present worth, years 11-55 years (factor=15.947)
Annual costs, years 56-60
VOC analysis (EPA Method 601)
VOC analysis (EPA Method 602)
Annual spring water sample analyses
QA/QC analyses (10% of analytic costs)
Annual monitoring report
LLNL tax (11% of outside charges)
Quarterly water level measurements (including 10
piezometers)
Semiannual ground water sample collection
Annual ground water sample collection
Quantity
0.35
128
12
3
1
111
39
50
3
91
0.35
111
12
3
1
111
37
37
Unit type
FTE
each
each
suite
report
well
well
well
spring
well
FTE
each
each
suite
report
well
well
well
Unit price
(1995 $)
238,500
50
50
545
15,000
62.50
250
125
125
430
238,500
50
50
545
15,000
62.50
250
125
Total
(1995 $)
83,475
257,280
2,139,796
6,400
600
1,635
864
15,000
2,695
6,938
9,750
6,250
375
39,130
83,475
173,111
2,760,598
5,550
600
1,635
779
15,000
2,592
6,938
9,250
4,625
T-23
-------
tCRL-AR-124061
Table 10. (Continued)
Final ROD for the GSA Operable Unit. Site 300
January 1997
Annual spring water sample collection
Maintenance of ground water sampling system
Project management
Total annual costs, years 56-60
Total present worth, years 56-60 years (factor = 0.681)
Total present worth of ground water and soil vapor
monitoring for 60 years (5 years after reaching MCLs)
Quantity
3
74
0.15
Unit type
spring
well
FTE
Unit price
(1995 $)
125
430
238^00
Total
(1995$)
375
31,820
35,775
114,938
78,273
4,978,667
Contingency costs and totals
Subtotal present worth of Alternative 3b
Contingency (20%)
Total present worth of Alternative 3b
15,747,651
3,149,530
18,897,181
T-24
-------
Table 11. ARARs for the selected remedy at the GSA OU.
Action
Ground water extraction
to
Source
Description
Application to the
selected remedy
Federal:
Safe Drinking Water Act [42
USCA 300 and 40 CFR 141.11-
141.16,141.50-141.51]
(Applicable: Chemical-specific)
State:
State Water Resources Control
Board (SWRCB) Resolution 92-49
(Applicable: Chemical-specific)
Cal. Safe Drinking Water
[California Health and Safety
Code Section 116365]
(Applicable: Chemical-specific)
Chapter 15, Code of California
Regulations (CCR), Title 23,
Sections 2550.7,2550.10
(Applicable: Chemical-specific)
Establishes treatment standards
for current potential drinking
water sources by setting MCLs
and non-zero Maximum
Contaminant Level Goals
(MCLGs), which are used as
cleanup standards. Those
standards for the GSA OU are
listed in Table 9 of the ROD.
Requires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water quality.
Establishes treatment standards
for current potential drinking
water sources by setting MCLs
which are used as cleanup
standards. Those standards for
the GSA OU are listed in Table 9
of the ROD.
Requires monitoring of the
effectiveness of the remedial
actions.
As part of the selected remedy,
VOC concentrations will be
reduced to MCLs in all ground
water in the GSA OU.
All cleanup activities associated
with implementation of the
selected remedy will be
conducted under the supervision
of the CVRWQCB.
As part of the selected remedy,
concentrations will be reduced to
MCLs in all ground water in the
GSA OU.
During and after completion of
the selected remedy,
concentrations of VOCs in in situ
ground water will be measured.
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Table 11. (Continued)
Action
Source
Description
Application to the
selected remedy
Ground water extraction (cont.) State: (cont.)
Soil vapor extraction
Water Quality Control Plan
(Basin Plan) for CVRWQCB
(Applicable: Chemical-specific)
SWRCB Resolution 88-63
(Applicable: Chemical-specific)
State:
Water Quality Control Plan
(Basin Plan) for CVRWQCB
(Applicable: Chemical-specific)
Chapter 15, CCR, Title 23,
Sections 2550.7,2550.10
(Applicable: Chemical-specific)
Establishes beneficial uses and
water quality objectives for
ground water and surface waters
in the Central Valley Region as
well as implementation plans to
meet water quality objectives and
protect beneficial uses.
Designates all ground and
surface waters in the State as
drinking water sources with
specific exceptions.
Establishes beneficial uses and
water quality objectives for
ground water and surface waters
in the Central Valley Region, as
well as implementation plans to
meet water quality objectives and
protect beneficial uses.
Requires monitoring of the
effectiveness of the remedial
actions.
As part of the selected remedy,
VOC concentrations in ground
water will be remediated to
levels listed in Table 9.
As part of the selected remedy,
VOC concentrations will be
reduced to levels protective of
drinking water beneficial use as
described in Section 2.10.1.
As part of the selected remedy,
VOC concentrations in soil vapor
will be remediated to levels
protective of ground water
(MCLs).
During and after completion of
the selected remedy,
concentrations of contaminants
in in situ soil vapor will be
measured.
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Table 11. (Continued)
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Action
Source
Description
Application to the
selected remedy
Contingency POU treatment at
water-supply wells
State:
Cal. Safe Drinking Water Act
(California Health and Safety
Code Section 116365)
(Applicable: Chemical-specific)
Establishes chemical-specific
standards for public drinking
water systems by setting MCL
goals.
As part of the selected remedy,
VOC concentrations will be
reduced to MCLs by POU
treatment at existing water-
supply wells, if necessary.
Treated ground water discharge
to
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SWRCB Resolution 92-49
(Applicable: Chemical-specific)
State:
SWRCB Resolution 68-16
(Anti-degradation policy)
(Applicable: Chemical-specific)
Requires oversight of
investigations and cleanup and
abatement activities resulting
from discharges of waste that
affect or threaten water quality.
Requires that high quality
surface and ground water be
maintained to the maximum
extent possible.
All cleanup activities associated
with implementation of the
selected remedy will be
conducted with oversight by the
CVRWQCB.
In the context of the selected
remedy, this is applicable to the
discharges of treated ground
water. The eastern GSA ground
water treatment system (GWTS)
discharges treated water to Corral
Hollow Creek under the
requirements of the current
NPDES permit issued by the
CVRWQCB. The central GSA
GWTS discharges to bedrock in
an onsite canyon under the
requirements of the current
Substantive Requirements issued
by the CVRWQCB.
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Table 11. (Continued)
I
Action
Source
Description
Application to the
selected remedy
Treated ground water reinjection Federal:
Safe Drinking Water Act
Underground Injection Control
Program (40 CFR 144.26-124.27)
(Applicable: Action-specific)
SWRCB Resolution 68-16 (Anti-
degradation policy)
(Applicable: Chemical-specific)
Treated soil vapor discharge
Local:
San Joaquin Valley Unified Air
Pollution Control District
(SJVUAPCD) Rules and
Regulations, Rules 463.5 and 2201
(Applicable: Chemical-specific)
Disposition of hazardous waste State:
Health and Safety Code, Sections
25100-25395, CCR, Title 22, Ch.
30: Minimum Standards for
Management of Hazardous and
Extremely Hazardous Wastes
(Applicable: Action-specific)
Requires monitoring for
reinjection of treated water.
Requires that high quality
surface and ground water be
maintained to the maximum
extent possible.
Regulates nonvehicular sources
of air contaminants.
Controls hazardous wastes from
point of generation through
accumulation, transportation,
treatment, storage, and ultimate
disposal.
During the selected remedy,
treated ground water would be
analyzed to verify complete
removal of VOCs to regulatory
treatment standards, prior to
reinjection.
During the selected remedy,
contaminated soil vapor will be
treated with GAC, or equivalent
technologies, and discharged to
the atmosphere. The compliance
standards for treated soil vapor
are contained in the current
Authority to Construct and
subsequent Permit to Operate
issued by the SJVUAPCD.
For the selected remedy, this
ARAR applies primarily to the
spent GAC vessels.
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Table 11. (Continued)
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Action
Source
Description
Application to the
selected remedy
Protection of endangered species
Floodplain protection
Federal:
Endangered Species Act of 1973,
16 USC Section 1531 et seq. 50
CFR Part 200, 50 CFR Part 402 [40
CFR 257.3-2J
(Applicable: Location-specific)
State:
California Endangered Species
Act, California Department of
Fish and Game Sections 2050-
2068
(Applicable: Location-specific)
State:
22 CCR 66264.18 (B)(l)
(Applicable: Location-specific)
Requires that facilities or
practices not cause or contribute
to the taking of any endangered
or threatened species of plants,
fish, or wildlife.
NEPA implementation
requirements may apply.
Prior to any well installation,
facility construction, or similar
potentially disruptive activities,
wildlife surveys will be
conducted and mitigation
measures implemented if
required.
Requires that TSD facilities
within a 100-year floodplain must
be designed/ constructed,
operated, and maintained to
prevent washout of any
hazardous waste by a 100-year
flood.
If it becomes necessary to install
point-of-use treatment for water-
supply wells CDF-1 or CON-1,
which are located offsite within
the 100-year floodplain, the POU
systems would be constructed in
accordance with this
requirement.
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Acronyms and Abbreviations
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UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January-1997
Acronyms and Abbreviations
AOS Adult Onsite
ARARs Applicable or Relevant and Appropriate Requirements
Cal EPA State of California, Environmental Protection Agency
CARE Citizens Against a Radioactive Environment
CCR Code of California Regulations
CDF California Department of Forestry
CDI Chronic Daily Intake
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
CFR Code of Federal Regulations
CMB Claystone Marker Bed
CPF Cancer Potency Factor
CVRWQCB Central Valley Regional Water Quality Control Board
DCE Dichloroethylene
DNAPLs Dense Nonaqueous Phase Liquids
DOE Department of Energy
DTSC California Department of Toxic Substances Control
EPA U.S. Environmental Protection Agency
ERD Environmental Restoration Division
FFA Federal Facility Agreement
FS Feasibility Study
FTE Full Time Employee
GAC Granular Activated Carbon
gal Gallons
gpm Gallons per minute
GSA General Services Area
GWTS Ground Water Treatment System
HE High Explosives
HI Hazard Index
hp Horsepower
HQ Hazard Quotient
HMX Cyclotetramethylenetetranitramine
IRIS Integrated Risk Information System
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UCRL-AR-124061
Final ROD for the GSA Operable Unit, Site 300
January 1997
LLNL Lawrence Livermore National Laboratory
MCLs Maximum Contaminant Levels
MEC Major Equipment Cost
MEIC Major Equipment Installed Cost
mg/kg Milligrams per kilogram
mg/L Micrograms per liter
NCP National Contingency Plan
NEPA National Environmental Policy Act
NPDES National Pollutant Discharge Elimination System
O&M Operation and Maintenance
OSWER Office of Solid Waste and Emergency Response
OU Operable Unit
PCE Tetrachloroethylene
PEFs Pathway Exposure Factors
POU Point of Use
ppbv/v Parts per billion on a volume-to-volume basis. Also referred to as ppbv
PRGs Preliminary Remediation Goals
PVC Polyvinyl Chloride
QA Quality Assurance
Qal Quaternary alluvial deposits
QC Quality Control
Qt Quaternary terrace deposits
RAOs Remedial Action Objectives
RES Residential Exposure
RfD Reference Dose
ROD Record of Decision
RWQCB California Regional Water Quality Control Board
SARA Superfund Amendments and Reauthorization Act of 1986
SJVUAPCD San Joaquin Valley Unified Air Pollution Control District
SVE Soil Vapor Extraction
SWRCB State Water Resource Control Board
SWRI Site Wide Remedial Investigation
TCE Trichloroethylene
TFC Total Field Cost
Tmss Miocene Cierbo Formation
Tnbsi Miocene Neroly Formation - Lower Blue Sandstone Member
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UCRL-AR-124061 Final ROD for the GSA Operable Unit, Site 300 January 1997
Tnb$2 Miocene Neroly Formation - Upper Blue Sandstone Member
Tnsci Miocene Neroly Formation - Middle Siltstone/Claystone Member
UCRL University of California Radiation Laboratory
UCL Upper Confidence Limit
VOCs Volatile Organic Compounds
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