United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R09-92/079
October 1991
SEPA Superfund
Record of Decision:
Westinghouse Electric
(Sunnyvale Plant), CA
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NOTICE
The appendices fisted in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement but adds no further applicable information to
the content of the document Ail supplemental material is, however, contained in the administrative record
for this site.
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50272.101
REPORT DOCUMENTA110N 11. REPORTNO. I ~ 3. R8c:IpIeIl1'a AccessIon NQ.
PAGE EPA/ROD/R09-92/079
4. TnIe and SUbtI1Ie S. Report Dale
SUPERFUND RECORD OF DECISION 10/16/91
westinghouse Electric (sunnyvale Plant), CA 6.
First Remedial Action - Final
7. AuIhor(a) 8. PerformIng OtganImIIon Rept. No.
9. Perfomdng OrgaInIzaIJon NIIme and ~ 10. Fl'qedtT8IkIWartI: una NQ.
11. Cordrad(e) or Gnm(G) NQ.
(e)
(G)
1~ SpoIISOItng 0rganImIIcIn NIIme and Address 13. Type elf Report & PerIOd CCMIr8d
U.S. Environmental Protection Agency
401 M Street, S.W. 800/000
Washington, D.C. 20460 14.
15. ~-"'J NcI8D8
PB93-964501
16. Ab8InIct (LImIt: 200 wonIs)
The 75-acre Westinghouse Electric (Sunnyvale Plant) site is an active industrial
facility located in Sunnyvale, Santa Clara Valley, California. The site currently
manufactures steam generators, marine propulsion systems, and missile-launching
systems for the U.S. Government. The area around the si te has been developed for
light industrial, commercial, and residential uses. A building (Building 21) used for
transformer manufacturing exists onsite. In the mid-1950s, Westinghouse Electric
(Sunnyvale Plant) manufactured transformers containing both Inerteen, which is a
dense, non-aqueous phase liquid (DNAPL) consisting of PCBs and trichlorobenzene, and
mineral oil as thermal insulating fluids. The storage and use of Inerteen and mineral
oil resulted in contamination of soil and two shallow aquifers beneath the site. In
addition, general handling practices and the onsite use of Inerteen as a weed killer
resulted in the release of PCBs into soil. In 1981, Westinghouse conducted site
investigations. In 1984 and 1985, Westinghouse, under state orders, removed
PCB-contaminated soil along fence lines and railroad spurs. During these
investigations, evidence of fuel hydrocarbon leakage to soil and ground water was
discovered coming from two underground fuel tanks. One tank was removed under state
(See Attached Page)
17. Document AnalysIs & Descrtptors
Record of Decision - Westinghouse Electric (sunnyvale Plant), CA
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs (benzene, TCE, toluene, xylenes), other organics (PCBs)
b. ~Terms
Co COSAl1 ReldIGroup
18. AYIIIIabIIIty St8Iement 19. Sec:urtty CIa8s (ThIs ReporI) 21. No. ~ P8gBs
None 78
20. Sec:urtty CIa8s (ThIs Page) 2:2. PItce
1\To" e
(See ANSI-239.18)
See 1mltnJcfI- on Re-
OPTIONAL FORM 272 (4-77)
(Fennelly NT1So35)
o..,-lkdIt 01 Commerce
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-1- -- -
EPA/ROD/R09-92/079
Westinghouse Electric (Sunnyvale Plant), CA
First Remedial Action - Final
Abstract (continued)
orders, and the remaining tank is slated for removal during the remedial action phase of
site work. This ROD addresses remediation of the contaminated shallow ground water and
soil, which pose the primary risks at the site. The primary contaminants of concern
affecting soil and ground water are PCBs, solvents, and fuel compounds.
The selected remedial action for this site includes excavating approximately 400 cubic
yards of contaminated soil containing greater than 25 mg/kg PCB; incinerating excavated
soil at an offsite federally permitted facility; filling and capping excavated areas;
permanent containment of contaminated ground water onsite where DNAPLs are detected,
using extraction; treating contaminated ground water; discharging treated ground water
onsite unless an alternative end-use for the treated effluent can be implemented;
notifying EPA of any future intention to cease operations, abandon, demolish, or perform
construction in Building 21; ground water monitoring; and implementing institutional
controls, such as land use restrictions. A ground water treatment technology will be
selected during the remediation design phase after treatability and bench-scale studies
are performed. The ground water treatment process may include using phase separation
with offsite incineration of any product phase recovered, membrane or carbon filtration
with offsite incineration of spent carbon and/or filtration membranes,
ultraviolet/chemical oxidation, air stripping, and a carbon polish.
PERFORMANCE STANDARDS OR GOALS: EPA is invoking an ARAR waiver of the requirement to
meet the MCL for PCB-contaminated ground water in the source area where DNAPL is detected
based upon the technical impracticability of remediation. Soil conta~ning greater than
25 mg/kg PCB will be excavated to a depth of 8 feet, based on EPA guidance for PCB
remediation at CERCLA sites with restricted access. The 25 mg/kg clean-up standard is a
To Be Considered (TEC) criterion. Chemical-specific ground water clean-up goals are
based on the more stringent of state or federal SDWA MCLs, including benzene 1 ug/kg .
(state), TCE 5 ug/kg (federal), toluene 1000 ug/kg (federal), xylenes 1750 ug/kg (state),
and PCB 0.5 ug/kg (federal).
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.RECORD OF DECISION
WESTINGHOUSE SUPERFUND SITE
Sunnyvale, California
u.S. Environmental Protection Agency
Region IX
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TABLE OF CONTENTS
Record of Decision for Westinghouse Superfund Site
Sunnyvale, California
Section Page
Part I. Declaration i
1.0 Site Name and Location i
2.0 Statement of Basis and Purpose i
3.0 Assessment of the Site i
4.0 Description of the Remedy i
5.0 Statutory Determinations iii
5.1 Protectiveness iii
5.2 Applicable or Relevant and Appropriate
Requirements iv
5.3 Reduction of Toxicity, Mobility
and Volume iv
5.4 Use of Permanent Solutions,
Alternative Treatment or Resource
Recovery Technologies iv
5.5 Cost Effectiveness v
Part II. Decision Summary 1
1.0 Site Name, Location and Description 1
1.1 Site Name and Location 1
1.2 Site Description 1
1.3 Topography 1
1.4 Land Use 1
1.5 Location and Facility Layout 2
1.6 Hydrogeology 2
2.0 Site History and Enforcement Activities 2
2.1 Background on Contamination Problems
at Westinghouse 2
2.2 Regulatory and Enforcement History 3
3.0 Highlights of Community Participation 4
4.0 Summary of Site Characteristics 4
4.1 Hydrogeology 4
4.2 Contaminant Source Areas 5
4.2.1 PCB and Chlorinated Benzenes 5
4.2.2 Gasoline and Related Compounds 7
4,2.3 High-Boiling-Point Hydrocarbons 7
4.2.4 Volatile Organic Compounds 8
4.3 Transport of Site Chemicals 8
4.3.1 Transport Mechanisms 8
4.3.2 Persistence 10
4.3.3 Transport Pathways 11
4.3.4 Potential Exposure Points 13
5.0 Summary of Site Risks 15
5.1 Human Health Risks 15
5.1.1 Exposure Assessment 16
5.1.2 Potential Exposure Pathways 17
5.1.3 Intake Assessment 17
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6.0
7.0
8.0
5.1.4 Risk Characterization
5.1.4.1 Soil Exposure
5.1.4.2 Groundwater Exposure
5.2 Environmental Evaluation
5.3 Uncertainty Analysis
5.4 Conclusions
Description of Alternatives
6.1 Introduction
6.2 Groundwater Remedies
6.2.1 No Action - Groundwater
6.2.2 Action Alternatives B, C and D
- Groundwater
6.2.2.1 Treatment Components For
Groundwater
6.2.2.2 containment Component for
Groundwater
6.2.2.3 General Components for
Groundwater
6.3 Soil Remedies
6.3.1 No Action -
6.3.2 Alternative
6.3.3 Alternative
Eight Feet
6.3.4 Alternative D - Excavation to
32 Feet
Summary of the Comparative Analysis of
Alternatives
7.1 Overall Protection of Human Health and
the Environment
7.2 Compliance with Applicable or Relevant
and Appropriate Requirements (IIARARslf)
7.3 Long-Term Effectiveness and Permanence
7.4 Reduction of Toxicity, Mobility or Volume
Through Treatment
7.5 Short-Term Effectiveness
7.6 Implementability
7.7 Cost
7.8 State Agency Acceptance
7.9 Community Acceptance
7.10 Comparative Evaluation Conclusions
The Selected Remedy
8.1 Description of the Selected Remedy
8.2 Statutory Determinations
8.2.~ Protectiveness
8.2.2 Applicable or Relevant and
Appropriate Requirements
8.2.3 Cost Effectiveness
8.2.4 Use of Permanent Solutions,
Alternative Treatment or Resource
Recovery Technologies to the
Maximum Extent Practicable
8.2.5 Preference for Treatment as a
Principal Element
Soil
B - 50il Capping
C - Excavation to
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21
21
21
21
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27
28
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31
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Figures
Figure 1..
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Location of Westinghouse Facility in Sunnyvale, CA
and South Bay Region
Facili ty Map.
General Sketch of Groundwater Mound contours in A
Aquifer
Location of Site Monitoring Wells
Distribution of PCB in Soil (>500 ppm)
Approximate Extent of DNAPL and PCB in A Aquifer
Conceptual cross-section Through Reservoir 2 Area,
Westinghouse Sunnyvale, CA
Distribution of PCB in B Aquifer
Distribution of Gasoline and High-Boiling-point
Hydrocarbons in the A and B Aquifers
Figure 1.0. Distribution of VOCs in A Aquifer
Figure 1.1. Sketch of General Conceptual Groundwater Remediation
System
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Tables
Table 1. Scenario 1, Worker Exposure: Ingestion of Chemicals in
Soil
Table 2. Scenario 1, Worker Exposure: Dermal Contact With
Chemicals in Soil
Table 3. Scenario 2, Residential Exposure: Ingestion of Chemicals
in Soil
Table 4. Scenario 2, Residential Exposure: Dermal Contact With
Chemicals in Soil
Table 5. Scenario 2, Residential Exposure: Ingestion of Chemicals
in Drinking Water
Table 6. Summary of Estimated Carcinogenic and Noncarcinogenic
Risks at the Westinghouse Site
Table 7. Remedial Alternatives (and the NCP Criteria)
Table 8. Groundwater Cleanup Criteria
Table 9. Carcinogenic Risks and Hazard Quotients of Ingesting
Groundwater with Concentrations at Water Quality criteria
Table 10. Sensitivity Analysis Summary (Costs of Groundwater
Extraction and Treatment System)
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PART I.
. DECLARATION
1..0
SXTE NAME AND LOCATXON
Westinghouse Electric Corporation
401 E. Hendy Avenue
Sunnyvale, California
EPA ID# CAD001864081
2.0
STATEMENT OF BASXS AND PURPOSE
This Record of Decision ("ROD") presents the selected remedial
action for the Westinghouse Electric Corporation Superfund site
("Westinghouse") in Sunnyvale, California.
This document was developed in accordance with the Comprehensive
Environmental Response, compensation, and Liability Act of 1980
(CERCLA) as amend.ed by the Superfund Amendments and Reauthorization
Act of 1986 (SARA), 42 U.S.C. S 9601 et sea., and, to the extent
practicable, in accordance with the National oil and Hazardous
Substances Pollution Contingency Plan, 40 C.F.R. S 300 et sea.,
("NCP"). The attached administrative record index (Attachment B)
identifies the documents upon which the selection of the remedial
action is based. .
The State of California, through the California Regional Water
Quality Control Board, concurs with the selected remedy.
3.0
ASSESSMENT OF THE SITE
Actual or threatened releases' of hazardous substance~ from this
site, if not addressed by implementing the response action selected
in this ROD, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
4.0
DESCRIPTION OF THE REKEDY
The selected remedy, which addresses the primary risks posed by
both soil contamination (which can be characterized as a principal
threat at this site) and shallow groundwater contamination (which
includes a detected, dense, non-aqueous phase liquid in the source
area that may also be characterized as a principal threat),
consists of the following components:
i
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(1)
(2)
(3)
(4)
(5)
(6)
(7)
Permanent containment, by means of groundwater extraction, of
contaminated groundwater in the source area where dense, non-
aqueous phase liquids (IDNAPLs") are detected, using
extraction;
Restoration of contaminated groundwater, using extraction, to
the CDHS Action Level for 1,3-Dichlorobenzene, the proposed
MCL for 1,2, 4-Trichlorobenzene and the federal and state
maximum contaminant levels (IMCLs"), with the exception of the
standard for polychlorinated biphenyls ("PCB") in the onsite
source area where DNAPL occurs;
Treatment of the extracted groundwater to meet all applicable
or relevant and appropriate ("ARARs") identified in this ROD
for this discharge, prior to discharge to the onsite storm
sewer, unless an evaluation indicates that an alternative
"end-use" for the treated effluent (such as use for facility
process. water) can be practicably implemented;
Removal of contaminated soil containing greater than 25 parts
per million PCB to a depth of eight feet (approximately 400
cubic yards);
Offsite incineration of excavated soils at a federally
permitted facility;
:Insti tutional controls, such as land use restrictions, to
prevent well construction (for water supply purposes) in
source areas that remain contaminated. Excavation below the
eight feet where soil has been removed will be restricted.
Restrictions will also preclude excavation, other than
temporary subsurface work in the upper eight feet and will
require complete restoration of any disturbed fill or the
asphalt cap once any such temporary work was completed;
(8)
A requirement that EPA receive notification of any future
intention to cease operations' in, abandon, demolish,' or
perform construction in (including partial demolition or
construction) Building 21 (see facility map, Figure 2);
Permanent and ongoing monitoring of the affected aquifers to
verify that the extraction system is effective in capturing
and reducing chemical concentrations and extent of the aqueous
phase plume and in containing aqueous phase contamination in
the DNAPL source area.
,
,
The process steps for treatment of extracted groundwater may
include phase separation (offsite incineration of any product phase
recovered), either membrane or carbon filtration,
ultraviolet/chemical-oxidation, air stripping, and a carbon polish.
The components of the system will be determined during the project
design and will be subject to modification during operation, based
ii
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-1-
upon the actual flow rates and chemistry of the extracted
groundwater (both of which may vary significantly over time).
Destruction of groundwater contaminants will be accomplished
through (1) offsite incineration of any separated product phase,
(2) offsite incineration of spent filtration membranes and/or spent
carbon and (3) ultraviolet/chemical-oxidation.
5.0
5.1
STATUTORY DETERMINAT:IONS
Protectiveness
The selected remedy is protective of human health and the
environment. Protection is achieved at this industrial site, and
in the aquifers extending beyond the Westinghouse property, in the
following ways:
(1)
(2)
(3)
(4)
(5)
(6)
The contaminated groundwater outside of the source area will
be restored to health-based standards, thus preventing
potential exposures, should these shallow aquifers ever be
used for water supply purposes.
Hydraulic containment of the source area will prevent
pollutant migration and further contamination of the shallow
aquifers, which are potential drinking water supplies. This
containment will be combined with a deed restriction to
prevent"construction of supply wells in the source area where
dense non-aqueous phase liquid has been detected.
The extracted groundwater will be treated, prior to on-site
discharge, to meet all ARARs identified for such discharges.
Contaminated soil containing greater than 25 parts per million
PCB, which represents a 10-6 risk in an industrial setting,
will be removed to a depth of eight feet, thereby preventing
potential exposure at the .surface, or in the shallow
subsurface (e.g., utility line workers).
"
The removed soil, spent filtration membranes and spent carbon
will be incinerated offsite, destroying the contamination and
thereby preventing any further possibility of exposure to
those contaminants.
(7)
Land use restrictions will prevent excavation, and therefore
exposure, in the area where contaminated soils remain at
depths greater than eight feet. Excavation in the upper eight
feet of the area where contaminated soils have been removed
will be restricted to temporary subsurface work and will
require' that any disturbance to the fill or the asphalt cap
must be restored once such temporary work is completed.
Land use restrictions will also prevent any residential
development in the source area, in order to reduce further any
risk of exposure due to contact with soil contamination.
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5.2
Applicable or Relevant and Appropriate Requirements
The selected response actions comply with federal and state
requirements that are legally applicable, or relevant and
appropriate, with the exception of the federal maximum contaminant
level for PCB in the source area. A waiver of this standard (which
is a "relevant and appropriate" standard) is justified in this case
based upon EPA's determination that it is technically impracticable
to meet it. This determination is made pursuant to CERCLA
S121(d) (4) (c) an~ is based on the following: (1) the presence of
spatially discontinuous, dense, non-aqueous phase PCB (Aroclor
1260) liquids in significant amounts; the heterogeneity of the
subsurface combined with low permeabilities; and the
characteristics of PCB (low solubility, high tendency to partition
onto organic materials and high viscosity). EPA has determined
that it is technically impracticable to meet the federal maximum
contaminant level for PCB in the DNAPL source area and that this
source area must be permanently contained.
5.3
Reduction of Toxicity, Mobility or Volume Throuqh Treatment
Soil containing greater than 25 parts per million PCB will be
excavated to a depth of eight feet and incinerated offsite, thereby
reducing the toxicity, mobility and volume of site contamination by
permanently destroying the PCBs with a treatment technology.
Toxicity, mobility and volume of groundwater contaminants will also
be reduced as extracted groundwater is treated by the combination
of phase separation (product phase will be incinerated), filtration
(filters will be incinerated) and ultraviolet/chemical-oxidation
(chemical destruction) steps.
The use of these "treatment technologies as an integral part of the
cleanup plan for both soil and groundwater demonstrates that the
cleanup plan satisfies the statutory preference for remedies that
employ treatment that reduces toxicity, mobility, or volume as a
principal element.
Use of Permanent solutions, Alternative Treatment or Resource
Recovery Technologies
While some hazardous substances will remain on the Westinghouse
property, contaminated soil that is removed will be incinerated
rather than land disposed. The treatment technologies that are
being applied to extracted groundwater will also destroy
contaminants (incineration and ultraviolet/chemical-oxidation).
The selection of these treatment technologies for soil and
groundwater demonstrate that where it is practicable, the selected
remedy includes permanent solutions.
5.4
Because removal or treatment of dense non-aqueous phase liquids at
this site is considered technically impracticable, the remedy
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requires long-term containment of the source area. Because this
remedy will result in hazardous substances remaining onsite above
health-based levels, a review will be conducted within five years
after commencement of the remedial action, and every five years
thereafter, to ensure that the remedy continues to provide adequate
protection of human health and the environment.
5.5
Cost Effectiveness
The remedy is cost effective because maximum protection is achieved
for the estimated cost of performance. The analysis contained in
the Feasibility study and this ROD demonstrates that additional
remedial action and the cost associated with that action would not
achieve a measurable reduction in risk, but that less effort and a
lower cost would result in a measurably higher risk at the site.
/O!ft> hI
Date .
~anie W. MCGovern
I) eqional Administra
v
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PART II.
DECISION SUMMARY
This Decision Summary provides an overview of the problems posed by
the Westinghouse Superfund site. It also includes a description of
the remedial alternatives considered, and the analysis of those
alternatives against criteria set forth in the National Contingency
Plan (NCP). This Decision Summary explains the rationale for the
remedy selection and how the selected remedy satisf ies the
statutory requirements of CERCLA.
1.0
SITE HAME, LOCATION, AND DESCRIPTION
1.1
site Name and Location
Westinghouse Electric Corporation
401 E. Hendy Avenue
Sunnyvale, California
1.2
site Description
The Westinghouse Sunnyvale Plant is a heavy industrial facility
which currently manufactures steam generators, marine propulsion
systems and missile-launching systems for the u.S. Department of
Defense. Headquartered in Pittsburgh, Pennsylvania, Westinghouse
purchased the original plant property in Sunnyvale in 1947 and
continued adding adjacent property until 1956. The property
currently constitutes 75 acres and generally lies between Hendy
Avenue, California Avenue, Fair Oaks Avenue, and N. Sunnyvale
Avenue. A parking area across the street on California Avenue is
also currently part of the plant property.
1.3
Topography
The facility is located in the Santa Clara Valley, approximately
five miles northeast of the Santa Cruz Mountains and five miles
south of San Francisco Bay. The regional topography slopes gently
downward north-north-east toward the Bay.
1.4
Land Use
The area around the site was used primarily for agricultural
purposes before it was developed. Since the 1950s and 1960s, it
has been developed for light industrial, commercial, or residential
use and was substantially landscaped or paved. Natural surface
drainage features were straightened and leveed as part of the
creation of the urban storm sewer drainage system.
While the site itself is zoned for industrial use, it is generally
surrounded by residential properties. Some of these parcels abut
the site, and others are as near as across a street (100 feet).
1
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1.5
Location and Facility Layout
Figure 1 shows the location of the site in sunnyvale. Figure 2
shows the locations of buildings at the current 75-acre property.
Two below-grade, 566,000-gallon reservoirs in the southeast and
northeast portions of the site provide water for fire protection at
the facility.
1.6
Hydrogeology
The subsurface in the area of the Westinghouse site consists of
alluvial sands and gravels with silt and clay layers. The
hydrogeology of this area is characterized by a high degree of
heterogeneity.
There are two shallow water-bearing units that have been affected
by contamination in the Reservoir 2 area of the Westinghouse site.
They have been designated as the A aquifer and the B aquifer and
are separated by a less permeable feature that is known as the A/B
aquitard. One .or more water-bearing sands may occur within a
particular aquifer zone.
The A aquifer extends from the water table at approximately 25 feet
. below ground surface to a depth of 45 to 50 feet below ground
surface (Figure 3). The B1 aquifer zone occurs between
approximately 50 to 70 feet below ground surface, and is separated
from the A aquifer zone by the five to eight foot thick A/B
aquitard.
The B aquifer zone is separated from the underlying C and deeper
aquifers by the B/C aquitard. The B/C aquitard is reported to be
approximately 50 to 100 feet thick and exists at depths ranging
from 100 to 150 feet below ground surface.
There is currently no known potable use of water from the A and B
aquifer zones on the Westinghouse property or in the surrounding
area. Municipal and industrial water supplies are drawn from below
the B/C aquitard.
.'
2.0
SXTE HXSTORY AND ENFORCEMENT ACTXVXTXES
2.1
Backgr~~d. on contamination Problems at westinghouse
In the mid-1950s, Westinghouse manufactured transformers in the
southeast portion of the site near the Reservoir 2 area in Building
21 (Figure 2). The transformers contained Inerteen and mineral oil
as thermal insulating fluids. Inerteen is a dense, non-aqueous
phase liquid ("DNAPL") which consists of approximately 60 percent
PCB Aroclor 1260 and 40 percent trichlorobenzene ("TCB"). Minor
amounts of monochlorobenzene ("CB") and dichlorobenzene ("DCB") are
also associated with Inerteen.
2
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The storage and use of transformer fluids (Inerteen) and mineral
oil resulted in contamination of soils and leakage into shallow
groundwater (the A and B aquifers) in the Reservoir 2 area.
Additionally, general handling practices and the onsite use of
Inerteen as a weed killer resulted in the release of PCB into
shallow soils along portions of the facility fenceline, in the
northwest yard, in the northeast yard, and along the railroad
tracks adjacent to Building 61.
In 1981, responding to the general public concern expressed
regarding PCB, Westinghouse conducted a study to determine the
nature and extent of PCB in the soils on site. Extensive shallow
soil contamination was discovered, and in 1984 and 1985, under
California Regional Water Quality Control Board Orders,
Westinghouse removed the PCB contaminated soils along fencelines
and railroad spurs.
The early 1980 investigations highlighted the area around Reservoir
2 as a more serious problem demanding further investigation. Deep
vadose-zone soils and groundwater were affected by release of
transformer fluids stored and handled in this area. In the course
of the continuing investigations in the Reservoir 2 Area, sampling
revealed evidence of fuel hydrocarbon leakage to soils and shallow
groundwater from two underground fuel tanks. One of these tanks
has been removed and the remaining fuel tank is not in use.
2.2
Regulatory and Enforcement History
From the time PCB contamination was reported in 1981, both the
California Water Quality Control Board (lithe Board") and the
California Department of Health Services (IICDHS") were involved in
overseeing the investigation and cleanup work done by westinghouse
at this facility. As mentioned above, Westinghouse conducted
shallow soil removal actions in 1984. and 1985 under Board Orders.
The site was proposed for listing on the National Priority List on
October 15, 1984, and final listing occurred on June 1, 1986. A
Potential Responsible Party ("PRP") search was conducted in 1986,
and the findings reported in a final document dated August 8, 1986.
The Board took the .lead agency oversight role until December of
1987. At that time the Board requested, due to resource and
staffing limitations, that EPA ~ssume the lead agency role.
EPA took over the lead, and issued General and Special Notice
Letters on January 2, 1988 and March 31, 1988, respectively. An
Administrative Order on Consent for the Remedial Investigation and
Feasibility Study ("RIfFS") was 'signed on August 24, 1988.
For the next two and one-half years investigations were conducted
in a phased approach until sufficient information was available to
propose a remedy. The draft RIfFS report was submitted in November
of 1990, and the final report was completed on June 11, 1991.
3
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3.0
HIGHLIGHTS OF COMMUNITY PARTICIPATION
When EPA assumed the lead-agency oversight role from the Board and
began negotiations with Westinghouse to conduct the RIfFS work, a
Community Relations Plan was developed for the Westinghouse site.
The first fact sheet announcing EPA's takeover of the lead and the
upcoming investigations was hand delivered to residents surrounding
the Westinghouse property and mailed to City officials and local
groups identified in the Community Relations Plan in December 1988.
The fact sheet generated little interest in the community.
Fact sheets were mailed to the community again in December 1990 and
in June 1991. These fact sheets included information concerning
the status of site investigations, the upcoming remedy selection
process, and the availability of the Administrative Record in the
City of Sunnyvale Public Library. The two fact sheets were mailed
to approximately 10,000 households and businesses in an effort to
reach as many community members as possible.
The June 1991 fact sheet presented the Proposed Plan and announced
the public comment period of July 1 to August 29, 1991 (60 days),
as well as the public hearing on the Proposed Plan on August 7,
1991. A press announcement in the Peninsula Times Tribune on June
30, 1991 and July 1, 1991 also contained this information, and on
the day of the public hearing, a local television station announced
the event.
The Proposed Plan public hearing was well attended (approximately
150 people attended), local news channels picked up the story, and
many comments were received from many residents (approximately
thirty) in the neighborhood near the Westinghouse site. These
residents have since formed a neighborhood association with the
focus of staying informed about Westinghouse cleanup issues and
having a voice in the decision-making process.
4.0
SUMMARY OF SITE CHARACTERISTICS
<'
4.1
Hydrogeology
The study area is underlain by alternating, discontinuous gravels,
sands, silts and clays typical of the alluvial overbank and
estuarine deposits of the region. The soils underlying the stUdy
area have highly variable percentages of clay, silt, sand, and
gravel, and stratigraphic contacts between soil types vary from
sharp to gradational. The coarse alluvial materials (sand and
gravel) form a series of water-bearing units or.aquifers, and the
inter layered fine grained deposits (silt and clay) act as confining
layers or aquitards which restrict vertical movement of groundwater
between adjacent aquifers.
Aquifer zones in the vicinity of the facility are generally
identified and correlated, with the shallowest water-bearing zone
4
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designated as the A aquifer zone. The A aquifer zone is underlain
by the B aquifer zone, which has been divided into the B1, B2, and
B3 aquifer zones. The approximate depths below ground surface at
which these aquifer zones occur in the vicinity of the Westinghouse
facility are as follows: A, 0 to 50 feet; B1, 50 to 70 feet; B2, 75
to 90 feet; and B3, 90 to 115 feet. One or more water-bearing
sands may occur within a particular aquifer zone.
Geologic cross sections through the Reservoir 2 area subsurface
have been prepared as part of the Remedial Investigation, and the
analysis of these indicate that the aquifer and aquitard materials
can be laterally discontinuous. However, the A/B aquitard appears
to be continuous under much of the Reservoir 2 area.
The regional groundwater flow is generally northward. In the A
aquifer, the gradient, which flows to the northwest, is relatively
flat and is estimated to be between 0.0005 to 0.010 ft/ft. Over
most of the study area, groundwater in the B aquifer flows toward
the north-northeast with a shallow hydraulic gradient of
approximately 0.0014 ft/ft. Velocities have been estimated at 2.6
to 522 feet per year in the A aquifer, and from .7 to 73 feet per
year in the B aquifer.' .
The main feature on the A aquifer groundwater elevation maps that
have been prepared as a part of the Remedial Investigation is a
groundwater mound centered to the north and northwest of Reservoir
2 (Figure 3). The presence of the groundwater mound is allegedly
due to leakage from underground water piping associated with the
pump house for the reservoir. Previous attempts to.. locate. the-
source of the pipeline leakage and correct it were unsuccessful and
additional studies to determine its source are. ongoing. If the
source cannot be eliminated, the presence of the mound will have to
be factored in to the design of the extraction system.
4.2
contaminant source Areas
Since the shallow soil removal, completed in 1984 and 1985, and
EPA's subsequent take-over of the lead agency role in oversight of
the work, the investigation has focused on the remaining
contamination in the southeast corner of the site where soils and
shallow groundwater have been affected. Approximately 65
monitoring wells have been constructed to date, and numerous soil
borings drilled. Figure 4 depicts the site monitoring well
locations.
4.2.1
PCB and Chlorinated Benzenes
Westinghouse stored Inerteen, a dense, non-aqueous phase liquid
("DNAPL") mixture of PCB and TCB in a 7, OOO-gallon above-ground
storage tank at the south end of Reservoir 2. The release of
Inerteen from the tank or leakage from the associated underground
pipelines in this area resulted in the infiltration of DNAPL
5
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1- .-
through the vadose zone and into the A aquifer (i. e., on top of the
A/B aquitard). Prior to the initiation of DNAPL recovery from
wells W38 and W48 in August of 1990, DNAPL thicknesses were
measured between none detected to 0.17 feet, and 0.58 to 2.83 feet,
respectively, in these wells.
The Inerteen tank was removed from the Reservoir 2 area in 1971.
The associated underground piping remains in place and is no longer
in use. The approximate extent of residual PCB in the vadose zone
soil is shown in Figure 5. The approximate extent of DNAPL and
aqueous phase PCB in the A aquifer is shown in Figure 6.
Inerteen was also released at several areas along the underground
Inerteen pipeline as indicated by the presence of PCB in the soils
along the pipeline. In addition, several inches of DNAPL were
identified on top of the AIB aquitard in well W46 near the
pipeline. The presence of DNAPL in this well is attributed to
ei ther leakage of Inerteen from the Inerteen pipeline or from the
former transformer filling station located in Building 21. The
detection of PCB and high-boiling-point hydrocarbons ("HBHCs") in
the groundwater from well W53 suggest that some PCB may have been
dissolved in the hydraulic fluid released from the adjacent former
hydraulic testing sump.
These detection~ of PCB DNAPL in the A aquifer are significant
because they are an extensive, persistent source of contamination
to groundwater involving PCB.
soil concentrations of PCB in the source area often exceed 500
parts per million (ppm) and are as high as ten or twenty thousand
ppm in a number of soil samples. These concentrations do not
attenuate appreciably with depth until the AIB aqui tard is
encountered. (Soils with concentrations of greater than 500 ppm
PCB are considered a "principal threat," as defined by the August
1990 EPA Guidance on Remedial Action for Sucerfund sites With PCB
contamination.) .
< <
Groundwater concentrations exceed the federal maximum contaminant
level ("MCL") of 0.5 parts per billion ("ppb") in the source areas
where DNAPL is detected and in the B aquifer. In several
instances, concentrations actually exceed the solubility limits for
PCB (2.7 ppb), indicating that some sort of facilitated transport
is occurring.
Limited information is available on the concentration and
distribution of PCB in soil beneath Building 21 where the
transformer manufacture occurred . Relatively low concentrations of
PCBs have been detected in one soil sample beneath the building
(10.7 mg/kg from the boring from Well 53; no other contaminants of
concern "COCS" were detected). Four wells have been installed in
Building 21 and no DNAPL has been encountered. Enough information
exists to indicate that soils beneath Building 21 do not serve as
6
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a continuing source of contamination to the groundwater.
4.2.2
'Gasoline and Related Compounds
Prior to 1986, Westinghouse stored gasoline in a 500-gallon
underground tank west of Building 12A at the north end of Reservoir
2. Releases of gasoline from this tank contaminated the soil and
groundwater beneath the tank.
The tank and surrounding gasoline-affected soils were removed in
1986, to a depth of 9 to 9.5 feet below ground surface. The area
and depth of excavation were limited because of concerns for the
structural integrity of Reservoir 2, Building 12A, and monitoring
wells W20 and W21.
Although no residual gasoline-affected soils were detected by the
analysis of soils from the boring for W41, soils containing
residual gasoline may remain in this area; the subsequent detection
of gasoline in the groundwater near the former tank indicates that
gasoline infiltrated below the depth of the tank excavation.
Gasoline concentrations in groundwater near the former tank (wells
W34 and W41, monitoring the A-aquifer) have ranged from 280 to 6800
ppb. .
Benzene, toluene, ethylbenzene and xylene are also detected in
wells W34 and W41. Benzene detections have ranged in concentration
from 0.7 to 800 ppb. Toluene concentrations in these two wells
range from one to 98 parts per billion. For ethylbenzene, detected
concentrations range from two to 540 ppb.
Gasoline, ethylbenzene, and xylene are also detected in the B-
aquifer in well W61. The most recent sampling in April of 1991
shows concentrations at 18,000, 300, and 830 ppb respectively. The
source of gasoline and related compounds in this well is uncertain
and there is some indication that detections here are related to an
upgradient source east of Fair Oaks Avenue from a property adjacent
to the Westinghouse property. This source on the adjacent property
is being investigated under the Underground storage Tank program
administered by the State of California.
4.2.3
High-Boiling-Point Hydrocarbons ("HBHCs")
The primary sources of releases of HBHCs at the site included three
13,000-gallon above-ground mineral oil storage tanks and a 20,000-
gallon underground fuel storage tank at the south end of Reservoir
2, and the former hydraulic testing sump adjacent to well W53 in
Building 21. The above-ground mineral oil tanks were removed from
the Reservoir 2 area prior to 1974, and the hydraulic testing sump
was backfilled and paved over with concrete prior to 1981. The
20,000-gallon fuel storage tank and associated piping remain in
place and are no longer in use. Subsequent to their release, these
HBHCs infiltrated through the vadose zone soils to the A aquifer.
7
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Residual HBHCs occur in the vadose zone beneath these sources; and
HBHCs in the form of a light, non-aqueous phase liquid floating on
top of the water table are localized to the area of wells W36 and
W38. Prior to the implementation of light non-aqueous phase liquid
(LNAPL) recovery from wells W36 and W38 in August 1990, LNAPL
thickness measurements ranged from none detected to 1..1 foot and
none detected to 0.01 foot, respectively, in these wells. .
While the presence of HBHCs has been investigated at this site,
they are not considered contaminants of concern due to low toxic
effects and no evidence of carcinogenicity. The selected remedy,
which includes extraction and treatment components, will remediate
these chemicals along with the more toxic and carcinogenic
compounds of concern found at the site.
4.2.4
'Volatile Organic Compounds
Concentrations of one or more volatile organic compound ("VOCs")
(excluding fuel hydrocarbons and DCB) were detected in the A
aquifer groundwater samples from eight monitoring wells located
near Building 21. The sporadic distribution and relatively low
concentrations of VOCs in the A aquifer (total VOC concentration
range: 0 . 7 to 131 parts per billion) suggests that these VOCs
entered the groundwater in an aqueous phase. Although a specific
source for these VOCs has not been identified, the distribution of
VOCs in the A aquifer indicates that the VOCs are localized near
Building 21.
4.3
Transport of site Chemica1s
Transport Mechanisms
4.3.1
This section discusses the transport of site contaminants of
concern ("COCS") and the factors that may have influenced chemical
migration.
Volatilization - Volatilization is considered to be a potential
transport mechanism possibly resulting in the loss of chlorinated
benzenes and VOCs in shallow'soil to the atmosphere... PCBs are
essentially "nonvolatile and therefore are expected to enter the
vapor phase only iri negligible amounts.
Water Solubility and Partitioninq - Chlorinated benzenes and VOCs
generally show increasing water solubility with decreasing
chlorination. As a whole, they are more soluble in water than PCBs
and will be transported by water in both vadose-zone and aquifer
soils to a larger extent. Chlorobenzenes and VOCs have relatively
low Koc and KQW values and thus are not strongly adsorbed to
particulate ma~ter.
PCB does not readily dissolve in water and is strongly adsorbed
onto soils. The following discussion presents the technical
8
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assumptions made in predicting transport. They are a mathematical
representation af the factors which govern how PCB may travel in
the aquifer, allowing the calculation of a prediction for how fast
and how far the contamination will travel.
Assuming a bulk density of 1.5 kilograms per liter, an estimated
porosity of 20 percent, a K value of 530,000 ml/g (based on
Aroclor 1254 in the absence or specific data for Aroclor 1260),
and an average organic carbon content of 0.2 percent in the A
aquifer, the retardation factor for aqueous PCB transport is
estimated to be approximately 7950. The actual retardation factor
for Aroclor 1260 may be much higher than the estimated value
because the K value is likely to be much larger than that of
Aroclor 1254 caue to its lower aqueous solubility. Using this
retardation factor, an average A aquifer groundwater gradient of
0.025, and a range of aquifer permeability from 1.0-2 em/sec to 1.0.4
em/sec, it is estimated that PCB Aroclor 1.260 should not have
migrated as an aqueous solute more than 0.08 to 8.2 feet from the
residual DNAPL in the aquifer matrix over the past fifty years in
the absence of any facilitated transport mechanism (i.e., cosolvent
effects or colloidal transport).
Because PCBs have been detected at distances (200 to 350 feet from
the source) I!l\?-ch.greater than would be predicted based on idealized
Darcian flow and adsorption/desorption kinetics, the transport of
PCBs in the groundwater may have been facilitated by either colloid
transport or cosol vent effects. The groundwater mound (see section
4.2) may have also contributed to the current distribution of PCB
in the A and B aquifers.
Colloid TranSDort Colloid transport could be a potential
mechanism for facilitating migration of PCB at the site because PCB
Aroclor 1.260 has a high K and K~ (these numbers represent the
tendency of a compound to artach to soil or other organic particles
in preference for dissolving in water or some other solvent), and
is thus strongly adsorbed on soil, colloids, and other
particulates. The presence of silty and clayey sands within some
portions of the A aquifer zone, however would act as a fine grained
filter material which may effectively negate this transport
mechanism. Similarly, in the absence of a preferential pathway
between the A and Bi aquifers, such as poorly sealed deep borings
or an incompetent feature in the aquifer (e.g., ancient root holes
or sand stringers), the potential for colloid transport through the
A/B1 aquitard is considered questionable because the silty clay
aquitard would be likely to filter out the colloids. However,
there is some evidence from the comparison of filtered and
unfiltered sampYes to indicate that colloidal transport may have
occurred.
Cosolvent Effects - Cosolvent effects may also be a mechanism for
facilitating the transport of PCB at the site because PCB Aroclor
1260 has a high affinity for hydrocarbon solvents (i.e., HBHCs and
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gasoline). PCBs have been detected at concentrations in excess of
the maximum aqueous solubility (i.e., 2.7 ppb) in wells W39 (8.~
ppb), W54 (7 to 25 ppb), and W61 (3.3 ppb). The increase in
apparent aqueous solubility may be the result of cosolvent effects
because these elevated PCB concentrations are coincident with the
highest concentrations of dissolved HBHCs and gasoline detected in
the site's monitoring wells (i.e., 6,200 ppb HBHCs in well W39,
17,000 ppb HBHCs in well W54, and 20,000 ppb gasoline in well 6~).
However, the gaspline in Well 6~ is thought to be from an offsite
source, rather than from the source area where PCB occurs.
Therefore there is some question about the hypothesis for this
well.
While TCB initially facilitated the transport of PCB through the
vadose zone due to its solvent effects, it does not appear to have
any current significant cosolvent effects for the transport of PCB
through the groundwater. The highest concentrations of TCB in the
groundwater are located in or near areas containing DNAPL (i.e.,
wells W22, W46, and W56). TCB was not detected in the majority of
the wells in which PCB was detected.
Preferential Pathwavs While no direct evidence from the
investigation indicates that a preferential pathway exists to
facilitate chemical migration, this transport mechanism has not.
been discounted. A preferential pathway is a more permeable
pathway through the aquifer material. These subsurface features
contain more sand or gravel and may have been ancient river
channels. Groundwater or contamination may be transported more
quickly through these old river channels than would be expected
given the regional flow rates.
Regardless of" the transport mechanisms involved for PCB transport
in the groundwater, the techniques used for investigating the
extent of PCB migration and the technologies for remediating PCBs
in the groundwater are the same.
4.3.2
Persistence
"
Highly chlorinated PCBs (e.g., Aroclor ~260) are relatively
resistant to biodegradation. Biodegradation of nonchlorinated VOCs
(benzene, toluene, ethylbenzene, xylene - often referred to as BTEX
- and acetone) is generally slow and not typically an important
environmental process, although fuel hydrocarbons can be
biodegraded under proper condi tions. Biodegradation data for
chlorinated VOCs are generally lacking for vadose-zone conditions,
but it is thought to occur very slowly in saturated conditions.
Oxidation, hydrolysis, and photolysis of PCBs, chlorinated
benzenes, and VOCs are all generally insignificant processes in
natural environments.
10
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4.3.3
Transport pathways
DNAPL (PCB and TCB) - A conceptual cross section showing the
pathways for the transport of PCB and TCB from the former Inerteen
storage tank area through the vadose zone and groundwater is shown
in Figure 7. PCB and TCB infiltrated into the site soils in the
form of a DNAPL. As noted above in the section on transport
mechanisms, TCB acted as a solvent to reduce the viscosity of the
PCB and facilitated the transport of PCB through-the vadose zone.
The release of Inerteen in the former storage tank area was of
sufficient magnitude to exceed the specific retention capacity (the
ability of the soil to hold a liquid as a sponge holds liquids) of
the soils and allow Inerteen to infiltrate to the water table.
Another release resulting in the infiltration of Inerteen to the
water table occurred from the Inerteen pipeline near Building 21 or
from the former transformer filling station in Building 21.
Because of the long period of time which has passed since the
Inerteen was used in the Reservoir 2 area, the PCB retained in the
vadose zone is considered to be held as specific retention. TCB is
no longer detected in these soils and it is assumed that, as a more
mobile constituent of Inerteen, it passed on through the vadose
zone leaving PCB behind. Gravity drainage of PCB is not considered
a current transport mechanism for the transport of PCB through the
vadose zone.
Upon reaching the AIB aquitard, the DNAPL spread laterally until
(1) it settled in small depressions along the top of the aquitard,
(2) the amount of DNAPL available for lateral migration - was
dissipated by the retention of DNAPL within the soil pores at the
base of the aquifer, or (3) the DNAPL pore pressure no longer
exceeded the minimum displacement pressure required for DNAPL entry
into water-filled soil pores of the aquifer.
The residual DNAPL in the aquifer matrix and the DNAPL located on
top of the AIB aquitard constitute an ongoing source of PCB and
chlorobenzenes in the groundwater~ These compounds slowly (over.
years) disso:!. ve. into the aquifer and are transported in the
groundwater in the same direction as the groundwater flow. since
the creation of the- groundwater mound at the north end of Reservoir
2, groundwater flow within the area affected by the groundwater
mound is outward from the center of the mound. The presence of the
mound has caused the distribution of PCBs in the groundwater to be
more widespread in the A aquifer than would have been expected in
the absence of the mound. The reversal in the groundwater gradient
in the southern portion of the site due to the mound has resulted
in the detection of some PCB at wells W39 and W10 located south
(i.e., in the original upgradient direction) of the former Inerteen
tank. -
Groundwater flow in the B aquifer is to the north-northeast, and
the orientation of the PCB and TCB plume in this aquifer is
11
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consistent with. the groundwater flow direction (Figure 8). As
noted in the section on transport mechanisms, the presence of PCB
and TCB in the B aquifer may be attributed to the migration of
these compounds through poorly sealed deep soil borings or some
incompetent feature in the A/B1 aquitard (i.e., ancient root holes
or sand stringers). The presence of PCBs in the B aquifer south of
the former Inerteen tank (i.e., at wells W49 and W25) indicates
that some of the PCB which had migrated to the south in the A-
aquifer had subsequently migrated across the A/B aquitard due to
the downward gradient between the A and B aquifers. As noted
earlier, the detection of PCB (3.3 ppb) above the aqueous
saturation limit (2.7 ppb) for this compound in well W61. in
conjunction with the detection of 20,000 ppb gasoline suggests that
cosolvent effects may be facilitating the transport of PCB in the
groundwater at the site.
Gasoline - The extent of dissolved gasoline in the groundwater of
the A aquifer is limited to the area containing wells W20, W41.,
and W34 (Figure 9). These wells are near or adjacent to the
location of the former underground gasoline tank at the north end
of Reservoir 2. No LNAPL has been detected in these wells. The
leakage of gasoline from the former tank resulted in the
infiltration. .of. gasoline to the groundwater table where it
dissolved into the groundwater. Because the former tank location
is approximately coincident with the center of the groundwater
mound, dissolved gasoline would be expected to flow somewhat
radially away from the tank site.
Gasoline was detected in the B aquifer well W61 east of Fair Oaks
Avenue. The transport of gasoline in the B aquifer is toward the
north to northeast consistent with the regional gradient. The
source of gasoline in the B aquifer at well W61. is uncertain
because (1.) a hydraulic connection between the gasoline detected in
the A aquifer wells at the north end of Reservoir 2 (i.e., wells
W34 and W41.) and the gasoline detected in well W61. in the B aquifer
is not apparent from the groundwater monitoring data, and (2) the
gasoline may be related to an upgradient source east of Fair Oaks
Avenue.
Hiah-Boilina-PointHvdrocarbons (IHBHCs") - Releases of HBHCs to
the soils and groundwater are associated with the three former
aboveground mineral oil storage tanks and the 20,000-gallon
underground tank at the south end of Reservoir 2 and the former
hydraulic testing sump adjacent to well W53 in Building 21.. Again,
Figure 9 presents the distribution of these compounds along with
the gasoline" compounds. Dissolved HBHCs have been detected in the
groundwater near these sources (i.e., wells W23, W24, W25, W39,
W47, W49, and W53). HBHCs in the form of LNAPL have only been
detected floating on the groundwater in wells W36 and W38.
Approximately 1..1 foot of LNAPL was detected in well W36 in
February 1990 and approximately 0.1 foot of LNAPLwas detected in
well W38 in January 1990. These were the maximum thicknesses of
12
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LNAPL detected in these wells during the remedial investigation
("RI"). After three months of product recovery from these wells
the LNAPL thickness in each well was reduced to approximately 0.001
foot. Because of the limited extent of LNAPL at the site, LNAPL
transport has not been considered a significant transport mechanism
at the site.
Dissolved HBHCs have been detected in the groundwater samples from
several monitoring wells in both the A and B1 aquifers. The HBHCs
in the groundwater will travel through the aquifers in the same
direction as the groundwater. However, as mentioned earlier, these
compounds are not considered as contaminants of concern in the risk
evaluation. They are being monitored and they will be addressed by
the groundwater extraction and treatment system during cleanup.
Volatile oraanic Com'Counds ("VOCS"\ - Concentrations of one or more
VOCs (excluding fuel hydrocarbons and DCB) were detected in the A
aquifer groundwater samples from eight monitoring wells located
near Building 21 (Figure 10). No halogenated VOCs were detected in
the B aquifer. The sporadic distribution and relatively low
concentrations of VOCs in the A aquifer (total .VOC concentration
range: 0.7 to 131 ppb) suggests that these VOCs entered the
groundwater in an aqueous phase. The distribution of VOCs in the
A-aquifer indicates that the VOCs are localized near Building 21.
The VOCs are dissolved in the groundwater and flow in the same
direction as the groundwater.
4.3.4
Potential Exposure Points
Surface and subsurface soils containing COCs to depths of five to
eight feet below ground surface are considered potential exposure
points for workers or future onsite residents. (Future onsite
residential use has been evaluated in the Risk Assessment as a
hypothetical case. The remedy selected in this ROD includes
institutional controls such as land use restrictions to prevent
residential development.) The onsite groundwater would be
considered a potential exposure point in the event that the
Reservoir 2 area were converted to residential use in the future
and that groundwater was extracted from the A and B aquifers for
domestic use at these residences. The groundwater is considered a
potential exposure point for offsite residences with existing wells
if the COCs at the site migrate toward these wells and if a conduit
exists for the transport of COCs into these wells.
Well surveys identified six wells that could potentially receive
COCs from site groundwater. These wells are described as follows:
.
(1)
A domestic and irrigation well (well 14) located downgradient
about 6,900 feet to the northeast of Reservoir 2;
(2)
A municipal well (well 82) located downgradient about 2,900
feet northwest of the facility;
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(3)
A deep well (depth greater than 500 feet below ground surface)
located in the center of the facility, about 1200 feet west of
Reservoir 2;
Three domestic water supply wells (wells 157, 156, and 183)
located approximately. 4,200 feet west-northwest, 4,300 feet
west-northwest, and 7,000 feet northwest of Reservoir 2,
respectively. A complete description of the well survey
conducted during the RI for the site and regional groundwater
use is included in Appendix G of the final RIfFS Report.
None of these six wells have been affected by Westinghouse
chemicals. For perspective, the nearest downgradient well is 2500
feet from the Westinghouse plume, which has traveled 350 feet from
the point of. ~el~ase in a 30- to 50-year time frame.
(4)
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5.0
SUMMARY OF SITE RISKS
5.1
Human Health Risks
This section summarizes the potential present and future human
health risks associated with - exposure to the contaminants of
concern ("COCS") in site soils and groundwater at the Westinghouse
site. The risk analysis has been conducted in order to evaluate
what risk the site currently poses, and what risk it may pose in
the future if no remediation occurs. This results of the risk
assessment serve as the rationale for the cleanup of the site.
The following chemicals constitute the COCs, for the Westinghouse
site:
contaminants of Concern at westinqhouse
Benzene*
Chlorobenzene (CB)
1,2-Dichlorobenzene (1,2-DCB)
1,3-Dichlorobenzene (1,3-DCB)
1,4-Dichlorobenzene (1,4-DCB)
1,2-Dichloroethane (1,2-DCA)
1,1-Dichloroethene (1,1-DCE)
cis-1,2-Dichloroethene (cis-1,2-DCE)
Ethylbenzene*
Polychlorinated biphenyls (PCBs)
Toluene*
1,2,4-Trichlorobenzene (1,2,4-TCB)
1,1,1-Trichloroethane (1, 1, 1-TCA)
Trichloroethene (TCE)
Xylene(s)*
* Benzene, Toluene, Ethylbenzene, and Xylene, fuel
components, are often referred to as a group with the
acronYm BTEX
The above list of chemicals includes all chemicals detected during
the RI with the exception of the high-boiling-point-hydrocarbons
(HBHCs) and acetone. The extent and distribution of HBHCs and
acetone has been characterizeid. The selected remedy, which
includes extraction and treatment components, will remediate these
compounds. However, the HBHCs are not considered contaminants of
concern or COCs due to low toxicity and the lack of evidence of
carcinogenicity. Acetone was detected twice at concentrations of
less than 10 parts per billion (cleanup levels are set at 3500
parts per billion) and is not considered a COC due to its
infrequency of detection and low concentration.
15
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5.1.1
Exposure Assessment
The exposure assessment identifies potential exposure pathways and
segments of the population that may be exposed to site-related COCs
via those pathways.
Potential Human ReceDtors - For the last 85 years the Westinghouse
site has been used only for industrial purposes (the property was
used industrially for many years prior to Westinghouse ownership)
and is expected to be used for such purposes in the future. Access
to the facility is controlled and the property is surrounded by a
high security fence. Future exposures to COCs at this site are
expected to be consistent with those arising from a limited access
industrial setting.
Exposure to soil containing COCs may occur among two types of
outdoor workers (defined as adults 18 years of age or older)
involved in activities in the onsite" area containing COCs in soil:
those engaged only in surface activities (surface workers), and
those engaged in subsurface construction activities (subsurface
workers) such as installation or maintenance of underground
utilities. The risk from incidental ingestion of soil and dermal
contact with soils are evaluated for both the surface and
subsurface workers. Inhalation risk for surface workers was
considered minimal because of the small surface area (fifty-foot
diameter at the surface) and its paved status. For subsurface
workers inhalation risks were factored into the evaluation.
The risk analysis also analyzed the risks which would exist if the
site were developed residentially. For this hypothetical future
scenario, where residential development and consequent exposures
would occur at this site, risks from ingestion and dermal
absorption of soil is evaluated for two receptor groups: children
aged one to six, and adults 18 years of age or older.
Because of the limited distribution of COCs in soil, the risk
evaluation addresses only soil in those area of concern where
contact with COCs may potentially take place. The following two
onsite areas are the only locations where such exposure is likely
(Figure 5):
«
(1) The roughly 650 square feet to the south of Reservoir 2 in the
former location of the aboveground Inerteen tank;
(2) Soil associated with the underground Inerteen pipeline with
which subsurface workers may come into contact during excavation
activities.
Because the groundwater is classified as a potential source of
drinking water, the hypothetical future residential scenario also
considers potential exposure to COCs in the groundwater via
domestic water use in the event that a groundwater well that
16
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intercepts shallow groundwater were installed and used at the site.
The exposure routes considered are the ingestion, dermal contact,
and inhalation of VOCs and PCB associated with residential exposure
scenarios.
While there are currently residences in close proximity to the
Westinghouse property, the exposure assessment indicates that these
neighborhoods do not constitute potential receptors. Soil
contamination is confined to a localized area completely within
Westinghouse property boundaries and is paved over with asphalt.
A mechanism to transport soil-borne COCs from the site does not
exist, and no domestic groundwater wells receive water impacted by
site COCs. High security fencelines and controlled entry to the
facility preclude any plausible scenarios for current exposure to
nearby residents".
5.1.2
Potential Exposure Pathways
Soil, groundwater, and air can serve as exposure media for the
potential receptor populations. This section discusses potential
exposure media and exposure routes for both the current-use and
future-use exposure scenarios.
The compounds that have been detected on site and are considered in
the following evaluation are as follows: For soil - PCB, three DCB
isomers, and three TCB isomers; for groundwater - PCB, three DCB
isomers, three TCB isomers, BTEX, TCA, 1,2-DCA,. 1,1-DCA, CB 1,1-
DCE, ciS-1,2-DCE, TCE, and acetone.
soil - PCB and TCB are the primary COCs detected in soils on the
site. There are three possible routes of exposure to contamination
in these soils: ingestion, dermal contact, and inhalation.
Groundwater - PCB, DCB, TCB, and VOCs have been detected in at
least one of the two water-bearing zones on and off the site
(contaminant plumes are presented in Figures 9, 10, 11, and 12).
Exposure to "groundwater COCs could occur if groundwater in the
contaminated areas of the A and B aquifers were used as a source of
water supply ~ There is currently no known use of water from these
two aquifers near the area of the Westinghouse contamination.
However, a hypothetical scenario involving such use has been
included in the exposure assessment. If the contaminated
groundwater from the A and B aquifers were used as a domestic water
supply, exposure could occur through ingestion, dermal contact,
inhalation, or ingestion of fruits and vegetables irrigated with
chemical-bearing groundwater. These aquifers are classified as
potential sources of drinking water.
5.1.3
Intake Assessment
This section integrates receptor populations, current and potential
future site activities, and exposure pathways into exposure
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scenarios representing '.reasonable maximum exposure (nRME") and
typical exposure conditions, enabling the evaluation of human
health risks.
Two exposure scenarios are evaluated in the intake assessment.
scenario one, the worker exposure scenario, applies to exposures
attributable to potential soil-related worker activities. Scenario
two addresses potential exposures to hypothetical future residents.
To evaluate potential worker exposures to soil at the site,
scenario one addresses typical and reasonable maximum exposures
(RME) to a surface worker and a subsurface worker over a period of
9 and 30 years, respectively. The specific subsurface construction
activity evaluated was installation and maintenance of utility
trenches. The soil exposure scenarios were used to estimate the
potential adverse health effects to surface and subsurface worker
populations via ingestion, inhalation, and dermal contact.
scenario two addresses soil- and groundwater-related exposures
assuming the Westinghouse property were to be converted to
residential use at some time in the future. In this scenario,
ingestion ana 'dermal absorption of COCs from exposure to
contaminated soil, and oral, dermal, and inhalation exposure to
groundwater is evaluated for adults 18 years of age or older and
children aged one to six years. (The inhalation pathway for soil
was considered minimal for this scenario because landscaping or
pavement would generally prevent airborne transport of contaminated
particles, the fifty-foot diameter area at issue is small, and the
risk for this pathway would be eclipsed by the ingestion and dermal
absorption pathways; i. e., there would be no measurable increase in
the total risk from this pathway.)
Tables 1 through 5 present pathway-specific equations, intake
parameters, and the references or rationale for selecting the
values used in estimating the chronic daily intakes ("CDIs").
Common to all the scenarios are fixed-receptor body weights and the
estimation of averaging times. The typical body weight used for
workers is 70 kilograms (kg). The typical body weight used for
adult residential receptors is also 70 kg. The typical body weight
for a one- to six-year-old was 16 kg.
Table 9 includes toxicity and carcinogenicity information for each
of the COCs, i. e., chronic reference doses and cancer potency
factors.
5.1.4
Risk Characterization
This section discusses the potential adverse noncarcinogenic health
effects and excess carcinogenic risks (i.e., additional cancer
risks above expected current background cancer risks) associated
with ingestion, dermal and inhalation exposures to the COCs
identified in soils and groundwater at the site. It should be
18
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noted that both the A and B aquifers are classified as potential
drinking water sources.
Noncarcinogenic health effects resulting from exposure to a single
compound, or a combination of compounds, are evaluated by
calculating a hazard quotient ("HQ"). The HQ is the ratio of
estimated chemical intake (i.e., CDI) for a particular route of
exposure to a reference dose ("RfD"). An RfD for chronic exposure
is an EPA-established value that represents chemical-specific,
exposure-route-specific doses to which nearly all populations may
be exposed for a period of up to 365 days per year for 70 years
without experiencing adverse health effects. For any single
chemical, or combination of chemicals where the HQ exceeds unity
(1. 0), potential health risks may be a concern. The sum of HQs for
all pertinent chemicals over all pertinent exposure routes (e.g.,
ingestion, dermal, or inhalation) is the total hazard index ("HIli).
The HI represents the total adverse health effect associated with
exposure to noncarcinogenic compounds of a particular exposure
scenario (e.g., typical exposure for a surface worker). As with
the HQ, an HI less than unity (1.0) is considered to be indicative
of no adverse health effects.
5.1.4.1
Soil Exposure
Noncarcinoqenic Risk - PCB and TCBs were the COCs considered for
potential soil exposures. Because there are no RfDs associated
with PCB, 1, 2 , 3 -TCB, or 1, 3 , 5-TCB, noncarcinogenic risks associated
with exposure to soil could not be evaluated for these compounds.
The Rfd for 1i2,4-TCB was used to calculate the risk of exposure to.
this isomer in soils.
Table 6 presents the calculated HIs associated with exposure to
soils in the area of concern for both the current industrial-use
scenario and the hypothetical future residential-use scenario. The
HIs for workers or hypothetical future residents do not exceed one
(1.0), thus no adverse, noncarcinogenic health effects are
associated with these exposures.
Carcinoqenic Risks - The results of calculations for exposures to
PCB- and TCB-containing soil via ingestion and dermal contact are
summarized in Table 6 for the onsite surface and subsurface worker
populations and hypothetical future residential populations.
The excess cancer risks for both the typical and RME scenarios for
all receptor populations exceed the ten to the minus six to ten to
the minus four (10-6 to 10-4) range considered acceptable by the EPA
(see the National Contingency Plan, 40 C.F.R.
S300.430(e) (2) (i) (A) (2». The primary exposure pathway
contributing to the excess risk appears to be the direct contact
with PCB-containing soil through dermal exposure.
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5.1.4.2
Groundwater Exposure
Noncarcinoqenic Risks - As shown in Table 6, the HI associated with
hypothetical future use of the A aquifer as a sole source of
domestic water exceeds 1.0 for both the typical and reasonable
maximum exposure scenarios for.children (19 and 57, respectively)
and for adults (8.5 and 26, respectively). 1,2,4-TCB is the
primary contributor to these HIs.
For the B aquifer, as shown in Table 6, the HIs associated with
hypothetical use of the B aquifer as a sole source of domestic
water do not exceed 1. 0 for tile typical or reasonable maximum
exposure scenarios for adults or children. Therefore, no adverse,
noncarcinogenic' heal th effects' are associated wi th the use of
groundwater from the B aquifer for domestic purposes.
carcinoqenic Risks - As shown in Table 6, the total estimated
excess cancer risks associated with the use of the A aquifer as a
sole source of domestic water are outside the range considered
acceptable by the EPA [10.6 to 10.' , pursuant to the National
Contingency Plan, 40 C.F.R. S300.430(e) (2) (i) (A) (2»). The
potential exposure to PCB through ingestion of contaminated
groundwater was primarily responsible for these excess risks.
Under the longer exposure period modeled under the RME scenarios,
dermal contact and inhalation of benzene ~nd 1,1-DCE also
contributed to the total excess cancer risk.
Total excess cancer risks associated with use of the B aquifer as
a sole source of domestic water are 2.73 X 10.5 and 1.88 x 10.5 for
the typical scenarios of a child and an adult, resrectivelY. Total
excess cancer risks of 4.33 X 10.5 and 9.89 x 10. were associated
with the RME to children and adults, respectively. These risk
levels, for both age groups, are within the 10.6 to 10.4 range of
acceptable human health risks for Superfund sites (see the National
Contingency' Plan, 40 C.F.R.' S300.430(e) (2) (i) (A) (2». Tpe
potential ingestion of PCB is primarily responsible for the risk
levels calculated for these sqenarios.
5.2
Environmental Evaluation
wildlife that may be present in. the vicinity of the site includes
raccoons, gophers, ground squirrels, rats, field mice and a variety
of birds, including burrowing: owls. The state of California
Department of Fish and Game has listed the burrowing owl (Athene
curicularia) as a flspecies of special concern." The burrowing
owl's primary habitat is grassland and open prairie. Neither of
these habitats exist in the immediate area of the site. Because
the site is covered with pavement or structures, access to the site
is restricted by a fence and sources of food are essentially
nonexistent, direct-contact exposures to COCs in soil on the site
by wildlife are unlikely. Wildlife exposure to COCs in surface
20
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water offsite is also not likely to occur because surface drainage
at the site is controlled by storm sewers. For these reasons,
impact to wildlife is expected to be minimal.
5.3
uncertainty Analysis
The risk evaluation for the Westinghouse site is based on data
collected at the site over a period of approximately three years.
Use of these data introduces uncertainty into the risk evaluation
regarding the degree that the data accurately represent typical
(average) and RME {reasonable maximum exposure) concentrations of
the COCs. For example, much of the data from the area of concern
was collected to identify "hot spots, " areas of
uncharacteristically high concentrations. Because these data were
used to derive average concentrations at specified depths upon
which "typical" exposure scenarios were based, the resulting
concentrations probably tend to overestimate such conditions.
Additionally, these calculated risk estimates are based on data
collected from the relatively small area near the Reservoir 2 and
should not be inferred to apply to the entire Westinghouse
property.
5.4
Conclusions
Because the excess upper bound lifetime cancer risks associated
wi th exposure to soils in the area of concern and contaminated
groundwater in the A aquifer exceed the risk. range considered
acceptable by the EPA, 10-6 to 10-4, remedial action is appropriate
for the Westinghouse site. Additionally, although the risk . levels
calculated for the B aquifer fall within the acceptable range,
concentrations of COCs that exceed MCLs occur in several wells,
thus necessitating remediation of the B aquifer.
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action selected
in this ROD, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
6.0
DESCRZPTZON OF ALTERNATIVES
6.1
Introduction
EPA has evaluated four alternatives in selecting the final cleanup
plan for the Westinghouse site. These alternatives were developed
from an evaluation that began by setting cleanup objectives, and
included studying the universe of applicable response actions and
technologies that might address the westinghouse site
contamination. This evaluation and screening process is documented
in detail in the Feasibility study.
Table 7 presents the alternatives that were developed.
the key features of each are outlined as follows:
Briefly,
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Alternative A - No Action
Alternative B - No excavation
Capping
Groundwater Treatment and Containment
Alternative
C - Excavation to Eight Feet
Offsite Disposal (C1) or Treatment (C2)
Capping
Groundwater Treatment and Containment
Alternative D -
Excavation to Thirty-two Feet
Offsite Disposal (D1) or Treatment (D2)
Capping
Groundwater Treatment and containment
Alternative A is the "no action" alternative. Alternatives B, C
and D all address groundwater with the same extraction and
treatment system. The only differences among these three lIaction
alternatives" is in how each of them addresses soil contamination.
Alternative B considers capping only as an option. Alternatives C
and D are excavation options (eight feet and 32 feet). These two
excavation options (C and D) consider offsite disposal versus
offsite incineration of the excavated soils in sub-alternatives C1,
C2, D1, and D2.
The federal or state (whichever is more stringent) maximum
contaminant .l-evels ("MCLs") for drinking water are relevant and
appropriate requirements to be met in the A and B aquifers, with
the exception of the source area covered by the waiver of the PCB
standard as described below. The cleanup standards that have been
set for groundwater are presented in Table 8. The cleanup level
selected for 1,3-DCB is a State Action Level (130 ppb), which is
not an ARAR but is a "to be consideredll or TBC criteria.
Additionally, the level selected for 1,2,4-Trichlorobenzene is a
proposed value and is expected to be promulgated in March of 1992
making it a TBC crit~ria along with the 1,3-DCB value. These
levels are set as a cleanup standards in the absence of a federal
or state promulgated drinking water standards and must also be met
in the A and B aquifers.
Soil cleanup has been set at 25 ppm, which is consistent with soil
cleanup standards for PCB spills at industrial facilities as
described in the Guidance on Remedial Actions for Superfund Sites
with PCB contamination (OSWER Directive No. 9355.4-01, August
1990). This guidance is a TBC criteria. TBCs are considered in
determining the necessary levels of cleanup for protection of
health or the environment.
The groundwater. cleanup standards and the soil cleanup standard
have been selected based on protectiveness criteria and the
requirements of law. Note that although the contaminated shallow
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A and B aquifers are not currently used as a source of supply, they
are classified as a potential source of drinking water. state
Water Resources Control Board Resolution 88-63 has incorporated
Board policy "Sources of Drinking Water" into the Basin Plan, which
is an ARAR for this site. Under this policy, the A and B aquifers
are potential sources of drinking water.
The following sections discuss the treatment, containment and other
general components of the four alternatives. The discussion is
organized into two parts: section 5.2 presents the components of
the groundwater remedies and Section 5.3 presents the components of
the soil remedies. See Table 7 for cost summary information for
each alternative.
6.2
Groundwater Remedies
The federal or state (whichever is more stringent) maximum
contaminant levels ("MCLs") for drinking water are ARARs to be met
in the A and B aquifers. The cleanup level for 1.,3-DCB is a State
Action Level (1.30 ppb), which is not an ARAR but is a TBC criteria.
Additionally, the proposed federal MCL for 1.,2,4-Trichlorobenzene
is TBC. These TBC standards are set in the absence of a
promulgated federal or state drinking water standards and must be
met in the A and B aquifers. The MCL standards, which are derived
from the Safe Drinking Water Act, are considered relevant and
appropriate to the groundwater portion of the remedy (NCP, 40
C.F.R. S 300.430(e)(2)(i)(C» and are to be met in the affected
aquifers. However, the remedy does not include a requirement that'
the federal MCL for PCB be met in the source area of the A aquifer .'.
For this limited area, for which all action alternatives considered
require permanent containment, (see section 6.2.2.2) an ARAR waiver
is invoked based upon technical impracticability, in accordance
. with CERCLA section 1.21.(d) (4)(C).
The substantive discharge standards under the Clean Water Act are
applicable requirements for discharge of any effluent from the
groundwater treatment system to the storm sewers; therefore, NPDES-
derived criteria will be the criteria for the discharge.
Substantive discharge requirements under ,the California Porter-
Cologne Act also apply to such discharges.
The California Regional Water Quality Control Board's Basin Plan is
also an ARAR, including the State of California's "Statement of
Policy wi th Respect to Maintaining High Quali ty of Waters in
California," Resolution 68-1.6, incorporated therein. This deals
with the maintenance of high quality waters in California.
Additionally, Resolution 88-63 is also incorporated into the Basin
Plan and applies to the classification of the shallow aquifers as
potential sources of drinking water.
.
other specific laws or regulations which apply or are relevant and
appropriate to particular treatment technologies are discussed
23
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below in section 5.2.2.1, for each technology described.
6.2.1
No Action - Groundwater
The "no action" alterna'tive represents a baseline against which the
other alternatives can be compared. It does not include
remediation of the groundwater. Only a monitoring program would be
implemented. This alternative assumes no capital costs for active
remediation, but only minor capital costs for expanding the
monitoring well network. As shown in Table 7, these capital costs
have been estimated at $62,000. Annual operation and maintenance
.( "0 & Mil) is estimated at $160,000, and total present worth (based
on thirty years) is estimated to be $3,700,000 (Table 10).
6.2.2
Action Alternatives B, C and D - Groundwater
Al ternati ves B, C and D all employ the same extraction and
treatment system. Because the contaminant plumes are small (300
feet long in the A Aquifer, and 500 feet long in the B aquifer; see
Figures 9-12). and because the aquifer yields are low (estimated
less than 50 gallons per minute), it was not practical to vary the
extraction system appreciably in any way (e.g., using different
pumping rates to achieve different cleanup time frames).
Additionally, because the source area where dense non-aqueous phase
liquid ("DNAPL") occurs demanded a containment approach, the
extraction system design for each alternative needed to address
containment.
The extraction and treatment system will be designed to reduce the
extent of the aqueous phase plume until cleanup standards have been
met throughout the A and B aquifers (with the exception of the PCB
standard in the DNAPL source area) and to contain permanently the
source area such that aqueous phase contaminants'will be prevented
from migrating beyond the source area. The following subsections
discuss the various components of the extraction and treatment
system, including the compliance points at the perimeter of the
DNAPL source area that is to be contained permanently.
6.2.2.1
Treatment Components for Groundwater
! .
The treatment options will be selected during the design phase
based on treqtaQility study results. The groundwater treatment
system must effectively remove PCB, VOCs, and petroleum
hydrocarbons (gasoline, diesel, and related compounds). These
chemicals have different physical and chemical characteristics
potentially requiring more than one technology. For example, air
stripping is effective for volatile petroleum and halogenated
compounds but not for semi volatile and nonvolatile compounds, which
can be effectively removed by carbon adsorption. Other options are
membrane technologies and ultraviolet-chemical oxidation. Physico-
chemical pretreatment for nonhazardous inorganics may also be
required.
24
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Additionally, it is expected that the chemistry of the treatment
system influent may alter appreciably over time. It will be
important to retain the flexibility to add, subtract or adjust the
components of the process train as this occurs. The underlying
feature of the treatment system that must be maintained, whatever
the actual components of the process train are, is the use of
destruction treatment technologies to reduce permanently the
toxicity, mobility and volume of COCs in the extracted groundwater.
The process train will be selected during the remediation design
phase after treatability and bench-scale studies are performed.
Product recovered by the extraction wells, or during initial phase-
separation steps, can be temporarily stored and then transported
offsite for incineration consistent with the laws applicable at the
time of such offsite transport. Modifications to the process train
may be necessary as the chemistry of the influent may alter
significantly over time.
Treated effluent will be discharged to the storm sewer, unless an
evaluation indicates that an alternative "end-use" (such as use as
facility process water or reinjection into the aquifer) can be
practicably implemented.
Treatabilitv Studies - Treatability studies will be conducted to
identify a cost-effective technology for treating the extracted
groundwater. Groundwater chemistry data will be used to assess the
general water quality and to calculate approximate concentrations
of contaminants in the treatment system influent. Aquifer test
data will be used to calculate approximate extraction flow rates. - . -
Treatment performance will be based on surface-water discharge
criteria.
The overall objective of the treatability studies is to provide
sufficient data to select and design a groundwater treatment system
that can effectively achieve the performance standards in a cost-
effective manner.
,
.<
The treatability studies will be performed in two phases. The
first phase will consist of bench-scale studies of GAC (granular
activated carbon) adsorption, ultraviolet (UV)-chemical oxidation
and membrane f il tration. Air stripping will be evaluated by
mOdeling the process. In Phase I, standard tests of the remedial
technologies will be used to (1) identify the differences in
process efficiencies and (2) examine the effects of process
variables on effluent chemical concentrations. The objective of
Phase I is to determine whether these technologies perform
satisfactorily for site conditions. The Phase I studies will be
used to select one or more processes that will be examined in
further detail in Phase II.
Phase II will be one or more pilot-scale studies. The objective of
Phase II is to (1) identify an "optimal" process, (2) evaluate the
25
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scale-up of the process and process design parameters, (3)
statistically compare removal efficiencies with discharge criteria,
and (4) estimate capital and operation and maintenance costs.
The fOllowing sections describe each of the technologies to be
tested in Phase I.
Granular Activated Carbon (GAC) Adsorntion - Adsorption of COCs
onto activated carbon occurs selectively when contaminated water
f lows through a bed of carbon granules. For the extracted
groundwater at this site, expected adsorption would be high for
PCB, medium for TCB, and low for VOCs. However,.if PCB is present
in colloidal form, GAC may not be as effective as expected based on
the chemical properties of PCB alone. If GAC is implemented at
this site, the used carbon must be sent offsite to a TSCA-permitted
incinerator to destroy the adsorbed COCs. Used carbon. is typically
regenerated, but no carbon regeneration facility has a..TSCA permit.
The incineration cost will be considered in the evaluation of this
technology.
Ultraviolet-Chemical Oxidation - Ultraviolet light in combination
with hydrogen" peroxide or ozone can be used to destroy completely
organic molecules to form carbon dioxide, water, and inorganic
salts. This advanced oxidation process has proven effective for
the full range of COCs found at the site. Pretreatment to remove
particles may be required because large particles may lessen the
treatment effectiveness. Acid may be added to control alkalinity.
If ozone is used, air emission control (pursuant to substantive
requirements of the" Bay Area Air Quality Management District I s
regulations) is required and will be considered in the evaluation
of this technology.
Air stripping - Air stripping will transfer volatile organic
compounds from the water phase to the gas phase using
countercurrent flow in a packed tower. For the extracted
groundwater at this site, an air stripper is expected to be very
effective for the low concentrations of chlorinated VOCs and
gasoline-related compounds and moderately effective for DCBs
because they are not as volatile as most of the VOCs, but not
effective for PCB or diesel fuel. Pretreatment may be required,
such as removing sUspended solids and adjusting pH or adding a
sequestriant to reduce scaling on the packing material. Both the
effluent gas (regulated by Bay Area Air Quality Management District
rules) and effluent water from the tower may be subjected to
further treatment by GAC in order to meet performance criteria.
Membrane Filtration - Ultrafiltration and reverse osmosis are the
two membrane filtration processes that will be evaluated during the
Phase I treatability studies. Ultrafiltration ("UF") depends on a
pressure driving force and a semipermeable membrane to separate
solutes, generally macromolecules with molecular weights above 500,
from water. Although the molecular weights of the COCs at the site
26
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are less than 500, field filtration of one groundwater sample
through a 0.45-micron filter removed 100 percent of the PCB and 30
to 50 percent of the TCB (DCB was not removed) . Thus UF may be
effective for concentrating and reducing the volume of COCs needing
treatment.
Osmosis is the spontaneous flow of a solvent (e.g., water) across
a semipermeable membrane from a dilute solution to a concentrated
solution. Reverse osmosis ("RO") uses differential pressure across
a membrane to cause water to flow in reverse from the concentrated
solution (concentrate) to the dilute solution (permeate). RO is
similar to UF but uses higher applied pressures and different
membranes, and can separate even low-molecular-weight species from
water.
Preliminary evaluation of both UF and RO will be performed to
determine the number and type of membranes to be evaluated during
bench scale tests.
6.2.2.2 Containment Component for Groundwater
While the extraction system will be designed to reduce the aqueous
phase concentrations of COCs and the extent of the plume in the A
and B aquifers, it will also be designed to prevent further
migration of COCs in both aquifers through gradient control. In
particular, a key objective will be permanent containment of the
DNAPL source area in the A aquifer such that aqueous phase
contaminants will be prevented from migrating beyond specified
compliance points. This key objective will be met using a densely
spaced line of groundwater extraction wells north of Building 21
(Figure 11).
All groundwater cleanup standards must be achieved in both the A
and B aquifers with the exception of the PCB standard in the DNAPL
source area of the A aquifer in the area where EPA has determined
that it is technically impracticable to meet this standard. This
area is defined by the wells outside the perimeter of the known or
suspected extent of DNAPL, and permanent containment of this area
is required.
EPA's current intent is to use the following monitoring wells to
define the compliance points for meeting all cleanup standards in
the A aquifer: W10, W24, W26, W30, W57, CCG-2, W58, W60, W31, W44,
W43, W63, W64, W65, W54, W55, W66. However, these points may be
adjusted, based upon information generated during remedial design
of the extraction system. The selected wells will serve as
compliance points where all standards must be met, including the
PCB standard. All points outside of this perimeter must also
achieve the cleanup standards for groundwater in the A and B
aquifers. Figure 6 depicts the extent of PCB contamination in the
A aquifer and the locations of the monitoring wells that are named
here as compliance points.
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6.2.2.3
General Components for Groundwater
Monitoring of water levels and water quality will be an integral
part of the extraction and treatment system.. The moni taring
program will be designed to ensure that gradients are controlled
and that satisfactory capture of aqueous phase contamination is
maintained. The monitoring program will also verify aqueous phase
plume reductions and achievement of cleanup standards, as well as
provide information that may be used to adjust the extraction and
treatment systems for optimum cost-effective performance over time.
Insti tutional controls such as land use restrictions will be
applied to the DNAPL source area within the compliance perimeter to
prevent water supply well construction here.
EPA is concerned that PCB in the B aquifer has been detected at
distances greater than would normally be predicted (see section
4.3.1. on transport mechanisms for site chemicals) for their
migration from the source area. The State and local agencies, the
City of Sunnyvale and the neighborhood residents have all expressed
similar concerns. While the risk to receptors does not increase
measurably over the next few years, or in any way constitute an
emergency, the threat from the groundwater does constitute an
imminent and substantial endangerment, and EPA believes that the
time to implementation of the remedial action should be as short as
practicable wi thin the legal constraints of CERCLA. From the time
an enforcement mechanism, such as a consent decree or an order,
becomes effective, it is estimated that time to full-scale start-up
of the groundwater.. extraction and treatment system would be
approximately two years.
Table 7 presents cost summaries of the alternatives. The direct
capital costs for groundwater remediation will be $850,000
including a 20 percent contingency. Indirect capital costs,
including a .15 percent contingency are $440,000. Operation and
maintenance costs (1.5 percent contingency included) are $60,000 for
the first year, and $29,000 for each year thereafter. .
6.3
soil Remedies
This section continues the discussion of the treatment, containment
and other general components of the four al ternati ves. The
previous section, 6.2, focused on the groundwater remediation. The
focus of this section is soil remediation.
As has been described, approximately 1.450 cubic yards of vadose-
zone soils contaminated with greater than 500 ppm PCB extend from
the surface down to the water table at 32 feet (Figures 6 and 8).
Subpart D of the Toxic Substance Control Act ("TSCA") PCB
regulations, which specify treatment, storage, and disposal
requirements for PCB, applies to excavated soils at the site. The
28
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Resource Conservation and Recovery Act ("RCRA") does not apply to
soil cleanup activities at westinghouse because PCB is exempt from
RCRA (because it is regulated under T8CA). The California storage
requirements for soils containing greater than 50 ppm PCB,
contained in C.C.R. Title 26, S22-6637~ and S22-66508, are ARARs
for the storage of hazardous waste at the site. Additionally, the
Bay Area Air Quality Management District's (BAAQMD) Regulation 8,
Rule 40 is an ARAR for excavation activities at the site. This
Rule deals with yolatilization of COCs.
It should be noted that the RIfFS Report estimates the volume of
PCBs in this 32-foot column of soil to be about 30 percent of the
total mass of PCB in the source area. PCB DNAPL contamination in
the A aquifer represents the remaining 70 percent of contaminant
mass.
As explained earlier, alternative A is the "no action" alternative.
Alternatives B, C and D all address groundwater contamination in
the same manner, differing only in the ways in which soil
contamination is addressed. Because the DNAPL in the A aquifer
outweighs soil contamination as an ongoing significant source of
contamination to groundwater (by virtue of its' greater mass and
immediate proximity), removal of contaminated soil does not
measurably reduce the threat of further contamination of
groundwater. However, containment of contaminated soil does
prevent direct contact with these soils at the surface, and removal
of shallow soil prevents direct contact exposure to subsurface
workers in shallow soils. The approaches to soil remediation in
Alternatives B, C and D reflect varying degrees of protection. from.
direct contact exposure.
Alternative B requires capping. Alternatives C and Dare
excavation options (eight feet and 32 feet). These two excavation
options (C and D) consider offsite disposal versus offsite
incineration of the excavated soils in sub-alternatives C~, C2, D1
and D2. Table 7 provides cost summary information for each
alternative and includes breakout information on the soil options
considered.
6.3.1
No Action - 50il
The "no action" alternative represents a baseline aqainst which the
other al ternati ves can be compared. It does not include any
remediation of the contaminated soils at the .site. The costs
associated with this alternative are those outlined in section
6.2.1 for groundwater monitoring only (Table 7).
6.3.2
Alternative B - 80il Capping
Alternative B does not consider any treatment components for soil.
29
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It is a containment remedy for soils, using an asphalt cap. The
purpose of the cap is to prevent direct contact with PCB-
contaminated soils at the ground surface, to eliminate air-borne
transport of contaminated soil particles, and to prevent
infiltration of water through the contaminated soils so that PCB
will not migrate to the groundwater. As discussed earlier, the
prevention of direct contact is the most significant protection
offered by the cap. Although the cap does prevent infiltration of
water that may transport PCB to groundwater, the groundwater is
already seriously affected by DNAPL. The extraction system, also
a part of Alternative B, addresses groundwater contamination.
Long-term maintenance of the asphalt cap, land use restrictions,
and ongoing monitoring are also part of this alternative.
Approximately 1450 cubic yards of shallow and vadose zone soils
contaminated with greater than 500 ppm .PCB are left. in place.
These contaminated soils extend from. the surface down' to the water
table at 32 feet (Figures 5 and 7).
The est~ated capital costs associated with capping the soil total
$37,000 (Table 10).
6.3.3
Alternative C - Soil Excavation to Eight Feet
Alternative C evaluates removal of soils containing greater than 25
ppm PCB to a depth of eight feet (approximately 400 cubic yards or
ten percent of the total contaminant mass, including DNAPL, in the
source area). Removed soils are replaced with clean fill and the
excavated area is capped with an asphalt cover to prevent
infiltration of water through contaminated soils below eight feet.
Again, as in Alternative B, long-term maintenance of the cap, 1and-
use restrictions, and ongoing monitoring are part of Alternative C.
Approximately 1050 cubic yards of soil containing PCB at
concentrations greater than 500 ppm are left in place. These are,
however, considered low threat soils because they exist at depth
where direct contact activities are not envisioned, because PCB in
these soils is very immobile, and because they do not pose a
significant threat to groundwater.
Sub-alternatives C1 and C2 weigh offsite disposal versus offsite
incineration of the excavated soils, respectively. Both of these
sub-alternatives must comply with TSCA requirements governing
transport and disposal or incineration of PCB. wastes. Sub-
alternative C2 is con~istent with the recommendation in guidance
that "principal threats" should be treated (Guidance on Remedial
Actions for Superfund Sites With PCB contamination, August 1990,
which has been identified as TBC criteria). Sub-alternative C2
also combines treatment and containment components.
The capital costs associated with soil removal to eight feet and
offsite disposal (C1) are $430,000. The capital costs of removal
30
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and incineration (C2) are $1,800,000.
6.3.4
Alternative D - Soil Excavation to 32 Feet
Alternative D evaluates removal of PCB-contaminated soils to a
depth of 32 feet. In the upper eight .feet, soil containing greater
than 25 ppm PCB will be removed. Below eight feet and down to 32
feet, soil containing greater than 500 ppm will be removed. This
constitutes approximately 1450 cubic yards of soil and represents
about 30 percent of the estimated total mass of PCB contamination
in the source area. DNAPL contamination in the A aquifer
represents the remaining 70 percent of estimated contaminant mass.
Sub-alternatives Dl and D2 weigh offsite disposal versus offsite
incineration, respectively. Both of these sub-alternatives must
comply with TSCA.requirements governing transport and disposal or
incineration of PCB wastes. Sub-alternative D2 is consistent with
the recommendation in guidance that "principal threats" should be
treated (Guidance on Remedial Actions for Superfund sites with PCB
contamination, August 1990). Sub-alternative D2 also combines
treatment and containment components.
The capital. costs for removal of 32 feet of soil and offsite
disposal (D1) are estimated to be $1,400,000. The capital costs
for removal to 32 feet and offsite incineration are estimated to be
$6,400,000.
7.0
SOHHARY OF THE COHPARAT:rvE ANALYSJ:S OF ALTERNATJ:VES
This section documents the key advantages and disadvantages among
the alternatives in relation to the nine criteria set forth in the
National Contingency Plan ("NCplt). The evaluations of the
alternatives are based on continued industrial use of the site.
Table 7 contains a summary presentation of the four al ternati ves in
relation to the nine criteria. The following nine sections
correspond to the nine crit.eria and each section contains a
discussion of all four alternatives with respect to that criterion.
7.1
Overall Protection of Human Health and the Environment
Alternatives B, C and D all provide equal protection from exposure
to contaminated groundwater because they all employ the same
groundwater extraction and treatment system. This system combines
containment and restoration of the contaminated A and B aquifers.
All three of these alternatives (B, C, and D) require the
groundwater to be cleaned up to the state or federal MCLs
(whichever are more stringent), with the exception of the PCB MCL
in the source area of the A aquif er (see Section 6.2.2.2).
Additional cleanup levels to be met in the affected aquifers for
1,3-Dichlorobenzene and 1,2,4-trichlorobenzene are based on TBC
criteria (a proposed federal MCL and a State of California Action
Level, respectively) in the absence of promulgated criteria. Also,
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these three alternatives include the same groundwater monitoring
program for verifying system performance, the same discharge
criteria for the extracted and treated groundwater, and the same
land use restrictions preventing water supply well construction.
These measures will prevent exposure to contaminants in the A and
B aquifers, which are classified as potential sources of drinking
water.
Alternatives B, C and D all prevent exposure to PCB-contaminated
soils. These soils are limited to a 50-foot diameter area south of
the Reservoir 2 and one smaller shallow (less than five feet deep)
area along the :Inerteen pipeline, all of which are on the
Westinghouse property, as described in section 4.2.1 (Figure 5).
Much of this soil contains concentrations of PCB greater than 500
ppm, which makes it, by definition, a "principal threat" (Guidance
on Remedial Actions For Superfund sites With PCB Contamination,
August 1991). All three alternatives require capping-with asphalt
and maintenance of. the cap. Land use restrictions would prevent
excavation below the eight feet where soil is removed for any of
these three alternatives. In Alternatives C and D, clean fill
would replace the removed soil. Land Use restrictions will permit
temporary subsurface work in the clean fill areas, but complete
restoration of any disturbance to the fill, or the asphalt cap,
will be required once the work is completed. Alternative D
requires removal of all contaminated soil down to the water table
at 32 feet below ground surface. Alternative C requires removal of
soil from the surface to a depth of eight feet. Alternative B does
not require any removal of soil, relying entirely upon the cap and
land use restrictions to prevent exposures to contaminated soil.
:It should be' noted that the DNAPL in the A aquifer, which is
generally located directly below the soil contamination and results
from the same release, eclipses the soils as a contaminant source
to the groundwater, i.e., removal of any amount of soil would not
accomplish a measurable reduction in the risk of further
contaminating groundwater because the DNAPL provides a far more
significant source of contamination. Protection from exposure to
groundwater contamination is addressed by the groundwater
extraction and treatment system discussed above.
Alternative A, no action, does not prevent exposure to contaminated
site soils or groundwater in any way. Neither does it prevent
continued migration of site contaminants in the uppermost aquifers,
which may pose a risk should these aquifers ever be used as a
source of supply water in the future. (Although there is no
current use of these aquifers, they are classified as a potential
source of drinking water.)
7.2 compliance With Applicable or Relevant and Appropriate
Requirements (ARARS)
The
Maximum
contaminant
Levels
(UMCLsU)
are
relevant
and
32
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appropriate requirements to be met in the affected aquifers (NCP
40 C.F.R. S300.430(e) (2)(i)(C). These are presented in Table 8:
Also presented in Table 8 are two cleanup levels to be met in the
affected aquifers that are based on TBC criteria in the absence of
any promulgated standard for those chemicals (1~3-Dichlorobenzene
and 1,2,4-Trichlorobenzene). Alternative A cannot meet the MCLs in
the affected aquifers. Alternatives B, C, and D comply with these
requirements everywhere in the A and B aquifers with the exception
of the A aquifer source area, where EPA has determined that it is
technically impracticable to meet the MCL for PCB. This limited
portion of the A aquifer is defined by specific compliance points
as discussed in Part II, Section 6.2.2.2 of this ROD. The
technical impracticability waiver of the "relevant and appropriate"
PCB MCL is based upon the presence of spatially discontinuous,
dense, non-aqueous phase liquids (PCB Aroclor 1260) in significant
amounts; the heterogeneity.' of the subsurface combined with low
permeabilities; and the characteristics of PCB (low solubility,
high tendency to partition onto organic materials and high
viscosity).
ARARs for soil cleanup levels have not been established. However,
a 25 ppm soil cleanup level for PCB contaminated soils at
industrial sites is consistent with Guidance on Remedial Actions
For Sucerfund Sites with PCB Contamination, OSWER Directive No.
9355.4-01, August 1990, which is a TBC criteria. The 25 ppm number
is based upon a risk analysis and includes a consideration of the
depth of contamination. It is not necessarily appropriate,
according to the guidance, to apply it to deep Yadose-zone soils.
Both Alternatives C and D meet this criterion from the surface to..
a depth of eight feet. Alternative D also removes all soil
containing greater than 500 ppm PCB from eight feet to 32 feet.
Alternatives A and B leave all contaminated soils in place.
The substantive discharge standards under the Clean Water Act are
applicable requirements for discharge of any effluent from the
groundwater treatment system to the storm sewers. The substantive
discharge requirements under the California Porter-cologne Act
(California Water Code, Division 7, section 13000, et sea.) also
apply to such discharges. Alternatives B, C and D all comply with
these requirements. Alternative A does not include a discharge
component. ..
,
The California Regional Water Quality Control Board's Basin Plan is
also an ARAR, including the State of California's "Statement of
Policy with Respect to Maintaining High Quality of Waters in
california," Resolution 68-16, incorporated therein. Alternatives
B, C and D all comply with these requirements, which deal with
maintenance of high quality waters in California. Alternative A
does not.
Alternatives B, C and D all include a groundwater extraction and
treatment system. Therefore the same ARARs apply in each
33
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alternative to the various components of the extracted groundwater
treatment system. If granular activated carbon adsorption is
implemented as part of the treatment process, Subpart D of TSCA is
an ARAR for the storage and treatment of spent carbon. The same
law is an ARAR for spent filtration membranes if they are included
in the treatment process. If ozone is used for the ultraviolet-
chemical oxidation process, or if an air stripper is added to the
process train, Bay Area Air Management District's Regulation 8,
Rule 47 is an ARAR for air emissions from either of these treatment
process components. Alternatives B, C and D comply with these
requirements. Alternative A does not employ any action that would
trigger these ARARs.
The Bay Area Air Management District's Regulation 8, Rule 40, which
deals with contaminant air emissions during excavation,. is an ARAR
for Alternatives C and D, both of which employ excavation as a
component of the remedy. Alternatives C and D comp~y with this
requirement. Alternatives A and B do not require any excavation
and therefore do not trigger these requirements.
Subpart D of' the TSCA, which specifies treatment, storage, and
disposal requirements for PCB, applies to excavated site soils.
Alternatives C and D each require excavation and short-term storage
of excavated soils. Sub-alternatives C1 and D1 require offsite
disposal of soil and trigger the TSCA disposal requirements. Sub-
alternatives C2 and D2 trigger the TSCA treatment requirements.
Alternatives C and D (inclusive of the sub-alternatives) comply
with these requirements concerning treatment, storage, and
disposal. Alternatives. A and B do not trigger these requirements.
The storage requirements for soils containing greater than 50 ppm
PCB contained in the California Code of Regulation, Title 26, S22-
66371 and S22-66508, are ARARs for the storage of hazardous wastes
at the site. Both Alternatives C and D, which include excavation
of soils, comply with these requirements. Alternatives A and B do
not employ any actions that trigger these requirements.
It should be noted that RCRA is not an ARAR for the treatment
storage or disposal of the Westinghouse soils because PCB is not a
RCRA waste, and no RCRA wastes are mixed with the PCB-contaminated
soils. Nor does. EPA believe the situation at this site is
sufficiently similar to that addressed by these RCRA requirements
to justify a. determination that they are relevant and appropriate
to this cleanup.
7.3
Long-Term Effectiveness and Permanence
Groundwater - Because removal or treatment of PCB DNAPL, which
occur in the shallow A aquifer, is considered technically
impracticable at this site, all three of the "action alternatives,"
B, C and D, require long term containment through hydraulic control
of the portion of the aquifer where DNAPL occurs (see Section
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5.2.2.2). In addition to containment of PCB within the area where
DNAPL occurs, the extraction and treatment system, (which is common
to all three of these alternatives) will effectively restore the
groundwater to all other MCLs. outside of the contained area all
MCLs, the CDHS. Action Level for 1,3-Dichlorobenzene, and the
proposed federal MCL for 1,2,4-Trichlorobenzene must be met in the
affected aquifers. Included in .the system are groundwater
monitoring, treatment of extracted groundwater to discharge limits,
and land use restrictions to prevent water supply well construction
in the contained area of the aquifer. While remediation of all of
the contaminated groundwater is technically impracticable and there
is an area of the A aquifer that will require long-term management,
the groundwater extraction and treatment system required in
Alternative B, C and D would be effective in preventing exposure to
contaminated groundwater.
The treatment technologies that are being applied to extracted
groundwater in Alternatives B, C and D will permanently destroy
contaminants through offsite incineration of spent filtration
membranes and/or spent carbon, or through ultraviolet chemical-
oxidation of extracted groundwater.
Soil - As noted earlier, the three "action alternatives," B, C and
D, are different from one another in the ways each addresses soil
contamination. The permanence and long-term effectiveness of each
of the soil options is discussed in the following paragraphs.
Alternative D requires removal of all soil containing PCB above 500
ppm, from the surface down to the water table at a depth of 32
feet. Additionally, soil containing more than 25 ppm PCB must be
removed in the upper eight feet of the excavation. This action
would result in the permanent removal of vadose zone soils
contaminated above these levels at the Westinghouse property.
However, permanence is also defined by the disposition of the
removed soil. As noted above, Sub-alternatives Dl and D2 require
offsite disposal and offsite incineration, respectively.
Incineration is the more permanent option for excavated soils
because the PCB is destroyed.
Alternative C requires removal of all soil containing PCB above the
cleanup standards, from the surface down to a depth of eight feet.
Again, these soils would be permanently removed from the
Westinghouse property, but their final disposition would determine
any additional permanence achieved, with incineration (Sub-
alternative C2) being a more permanent action than land disposal
(Sub-alternative C1). Also, Alternative C is a less permanent
solution than Alternative D in that contaminated soils remain in
place below a depth of eight feet. For Alternative C, protection
is achieved w~th.land use restrictions that prevent excavation work
below eight feet, allows only temporary excavation above eight
feet, and by capping.
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Alternative °B, which requires capping with no soil removal or
treatment, represents a "containment only" approach to contaminated
soils. Of the three "action alternatives," it is the least
permanent solution. In addition to the cap, land use restrictions
and the facility fence are required for prevention of exposure to
contaminated soils at the site.
Alternative A, no action, does not provide permanent or effective
protection from site contamination.
7.4
Reduction of Toxicity, Mobility or Volume Through Treatment
The groundwater extraction and treatment system, which is common to
Al ternati ves B, C and D, treats extracted groundwater with
permanent destruction technologies. Recovered product phases,
filtration membranes, and activated carbon filters will be
incinerated offsite. Ultraviolet/chemical-oxidation vill destroy
contaminants by oxidizing them. Destruction results in a reduction
of the toxicity, mobility and volume of site contaminants.
Sub-alternatives C2 and D2 require incineration of PCB-contaminated
soils that have been removed from the site. This treatment results
in a reduction. of the toxicity, mobility and volume of soil
contaminants. D2 provides the greatest reductions because more
soil is removed and incinerated.
Alternative B, sub-alternatives C1 and D1 do not require treatment
of soils, therefore these alternatives do not achieve reductions in
toxicity, mobility or volume of soi1 contaminants.
Alternative A does not achieve reductions in toxicity, mobility or
volume for soil or groundwater contaminants.
7.5
Short-Term Effectiveness
Al ternati ves C and D require soil excavation, which introduces some
risk of soi1 exposure to excavation workers through potential
inhalation, ingestion, and dermal contact; this risk is greater for
Alternative D, the deeper excavation, because the exposure time is
greater. Dust control measures coupled with proper health and
safety procedures, including protective clothing, can mitigate the
risks posed during excavation work. Alternative B introduces a
small short-term exposure risk to the workers installing the cap
over the affected soils; however, this risk is easily mitigated by
health and ~~fe~y procedures. Alternatives B through D include
groundwater extraction well construction, which introduces a small
short-term risk to workers that can be mitigated through standard
heal th and safety procedures. It is not anticipated that any
short-term risks of exposure are posed to nearby residents by
implementation of any of the four alternatives. There are no
short-term risks associated with implementing Alternative A, the no
action option.
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7.6
:rmplementability
All alternatives are administratively feasible. No problems are
anticipated regarding the availability of material to perform
remediation in accordance with any of the alternatives.
All alternatives are technically feasible. The technologies
required in each alternative are practical and proven. Alternative
A is the easiest to implement. Groundwater remediation is equally
implementable for Alternatives B, C and D. Soil remediation is
relatively easy for Alternative B, more difficult for Alternative
C, and most difficult for Alternative D.
7.7
Cost
Table 7 presents cost information at the bottom of the table for
each alternative. Alternative A, which only involves expansion of
the existing monitoring program is the least expensive. The
present worth of capital and operations and maintenance ("0 & Mil)
costs for thirty years is $3.7 million.
Alternatives B, C and D have the same 0 & M and direct costs for
groundwater remediation, but differ in capital costs for soil
remediation. Rounded capital costs for Alternative Bare $1..3
million, the majority of which is for groundwater remediation.
Alternatives C and D include soil excavation, and the sub-
alternatives using disposal are considerably less expensive than
those using incineration. Capital costs of sub-alternatives using
disposal are $1..7 million for C1., and $2.7 million for Dl. Capital
costs of sub-alternatives using incineration are as follows: C2,
$3.1 million; D2, $7.7 million.
The approximate' present worth cost for thirty years for each
alternative is listed below:
o
o
o
o
Alternative A - $3.7 million
Alternative B $6.5 million
Alternative C - Cl, $6.9 million;
Alternative D - Dl, $7.8 million;
C2, $8.3 million
D2, $12.9 million
Alternative C, by removing ten percent of the PCB-containing soils
requires thirty percent (Cl) to 135 percent (C2) more in capital
costs than Alternative B. Alternative D, by removing twenty
percent more of the PCB-containing soils than in Alternative C,
requires 56 percent (Dl) to 150 percent (D2) more in capital costs
than Alternative C.
Sensitivity Analvsis - Because the treatment system for extracted
groundwater is not fully defined, costs for extraction, treatment,
and monitoring were approximated using the available data. To
evaluate the cost sensitivity of the design assumptions, specific
components of the remediation scheme were varied to generate a
37
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range of costs. Design assumptions were varied for items with a
high uncertainty and items for which a slight change significantly
impacted the overall costs.
The sensitivity analysis is discussed in detail-in Section 12.5.7
of the Remedial Investigation and Feasibility Study Report. Table
10 summarizes the results of the analysis. The no action
alternative is the most sensitive on a percentage basis (24
percent) because the overall capital costs are low. Sensitivity
decreases as capital costs increase (from an average of ten percent
for Alternative B to an average of two percent for Alternative D2).
In contrast, for 0 & M costs, there is a difference of five percent
for Alternatives A, B, C, and D. Present worth costs vary between
three and seyen percent from the median for all four alternatives.
7.8
state Agenoy Aooeptanoe
The California Regional Water Quality Control Board ("the Board")
commented on the Proposed Plan and stated that it was in general
concurrence with it. The Board's stated concerns focus on the
waiver of the drinking water standard for PCB in the source area
and the associated permanent loss of a potential drinking water
supply. However, the State concurs with the technical basis for
the waiver and states that it "believes that the potential drinking
water source loss may be allowable in this specific case." A full
response to co~ents received from the RWQCB -can be found in the
attached Responsiveness Summary, Attachment A.
7.9
community Acoeptance
As discussed in Part I of this ROD in section 3.0, Highlights of
community Participation, the Proposed Plan public hearing was well
attended and approximately thirty comment letters were received
during the sixty-day public comment period.
i-
There were many concerns raised by community members at the public
hearing and 'in ~he written comments received. The major concern
was with waiving the relevant and appropriate maximum contaminant
level (MCL) for PCB in the A aquifer source area where DNAPL
occurs. Some commenters indicated that all contamination should be
removed from the site. None of the comments received provided EPA
with any technical or health risk justifications for not invoking
the waiver. EPA remains convinced that removal of the DNAPL is
technically impracticable and that there is merit in acknowledging
so with the technical impracticability waiver. This action
provides a clear basis for the requirement to permanently contain
the source area. The permanent containment component is a
significant feature of the remedy designed to provide ongoing
protection of the surrounding aquifers. EPA believes that the
technical impracticability waiver coupled with the requirement to
contain permanently and to monitor the area covered by the waiver
provides a significant protection from exposure to contaminated
, '
38
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groundwater.
Another key concern voiced by the community is related to the
potential for health effects to residents and workers. While the
concerns raised regarding health effects were broader than are
typically addressed in the process leading to a selection of a
cleanup remedy, the Agency for Toxic Substances and Disease
Registry ("ATSDR") and California Department of Health Services
("CDHS") are currently conducting a health assessment which does
consider possible health effects to both onsite workers and offsite
residents. This health assessment mayor may not recommend further
health activities such as "health studies" based upon the data
evaluated. Based on the location and limited extent of
contamination in addition to 'the lack of evidence that any
exposures are occurring, EPA believes that the risks associated
with the site are very low. However, in order to facilitate
communication between community members and the agencies performing
the health assessment, EPA is taking several measures which are
outlined in the Responsiveness Summary. One of these measures is
a request to CDHS that a notice of the availability of the draft
health assessment be mailed to all persons who commented on the
Westinghouse' Proposed Plan.
Additional concerns raised by the community are addressed in detail
in the attached Responsiveness Summary, Attachment A.
7.10
Comparative Evaluation Conclusions
Based on the comparative analysis EPA selects Alternative C2 as the,
alternative that represents the best balance of the nine criteria.
Alternative A is unacceptable because it does not provide adequate
protection of human health and the environment. Al ternati ves B, C,
and D provide the equal protection of human heal th and the
environment regarding groundwater exposure, and the cost for
groundwater cleanup is the same for all three alternatives.
Alternatives B, C and D differ by the degree of soil remediation
required. The lateral area of ~ontaminated soil is small (50-foot
diameter), but the concentrations are high. The decision to remove
soil in this area to a maximum depth of eight feet, rather than
capping it in place (Alternative B) less expensively, is reasonable
given the plausible scenarios ~or shallow excavation activities
which might occur on this industrial property in the future.
Removing all. contaminated soil to the depth of the water table at
32 feet (Alternative D) does not'achieve a measurable reduction in
risk due to direct contact exposure because there is no plausible
expectation that subsurface work would occur below the eight-foot
level. Therefore, the much higher additional cost for this
alternative is not justified. Land use restrictions preventing
subsurface work below eight feet would provide adequate protection
in these circumstances. Additionally, it has been explained that
DNAPL contamination in the A aquifer outweighs the deep vadose-zone
.
39
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soils as an ongoing contributing source of contamination to
groundwater such that soil removal does not result in any
measurable reduction in risk to groundwater. The selection of
incineration (C2) over land disposal (C~) is based upon the
statutory preference for remedies that employ treatment and use
more permanent solutions to the extent practicable.
8.0
8.1
The Selected Remedy
Description of the selected Remedy
The selected remedy, which addresses the primary risks posed by;
both soil contamination (which can be characterized as a principal
threat at this site) and shallow groundwater contamination (which
includes detected DNAPL in the source area that .may also be
characterized as a principal threat), consists of the following
components: "
(~)
(2)
(3)
(4)
(5)
(6)
Permanent containment of contaminated groundwater in the
source area where DNAPL is detected, using extraction;
Restoration of contaminated groundwater, using extraction, to
the CDHS Action Level for ~,3-Dichlorobenzene, the proposed
MCL for ~, 2 ,4-Trichlorobenzene and the federal and state
maximum contaminant levels ("MCLs"), with the exception of the
standard for polychlorinated biphenyls ("PCB") in the onsite
source area where DNAPL occurs (these cleanup levels are
presented in Table 8);
Treatment of the extracted groundwater to meet all ARARs
identified for this discharge prior to discharge to the on-
site storm sewer, unless an evaluation indicates that an
alternative "end-use" for the treated effluent (such as use
for facility process water) can be practicably implemented;
Removal of contaminated soil containing greater than 25 parts
per million PCB to a depth of eight feet (approximately 400
cubic yards);
.
Off-site incineration of excavated soils at a federally
permitted facility;
xnstitutional controls, such as land use restrictions, to
prevent well construction (for water supply purposes) in
source areas that remain contaminated. Excavation below the
eight feet soil has been removed will be restricted.
Restrictions will also preclude excavation, other than
temporary subsurface work in the upper eight feet and will
require complete restoration of any disturbed fill or the
asphalt cap one any such temporary work was completed;
40
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(8)
A requirement that EPA receive notification of any future
intention to cease operations in, abandon, demolish, or
perform construction in (including partial demolition or
construction) Building 21 (see facility map, Figure 2);
Permanent and ongoing monitoring of the affected aquifers to
verify that the extraction system is effective in capturing
and reducing the size and contaminant concentration of the
aqueous phase plume and in containing aqueous phase
contamination in the DNAPL source area.
(7)
The process steps for treatment of extracted groundwater may
include phase separation (offsite incineration of any product phase
recovered), either membrane or carbon filtration,
ultraviolet/chemical-oxidation, air stripping, and a carbon polish.
The components of the system will be determined during the project
design and will be subject to modification during operation, based
upon the actual flow rates and chemistry of the extracted
groundwater (both of which may vary significantly over time).
Destruction of groundwater contaminants will be accomplished
through (1) offsite incineration of any separated product phase,
(2) offsite incineration of spent carbon and/or filtration
membranes and (3) ultraviolet/chemical-oxidation.
It is estimated that once the remedy is completed and the
groundwater. . meets the required cleanup standards, total
carcinogenic risk from ingesting groundwater from this site will be
8.5 x 10-5. The noncarcinogenic hazard index for ingestion of site
groundwater meeting the cleanup criteria (MCLs) is equal to 0.34.
Because the remedy eliminates the risk pathways associated with
residual contamination left on site (the DNAPL source area and the
contaminated soils. below eight feet), the risk of exposure to this
contamination is effectively eliminated.
The points of compliance defining the groundwater source area are
described in section 6.2.2.2. They consist of monitoring wells at
the perimeter of the groundwater source area, within which the
waiver for the requirement to meet the PCB MCL in groundwater will
be invoked, and for which permanent containment.is required. The
selected remedy requires all MCLs, the CDHS Action Level for 1,3-
Dichlorobenzene, and the proposed MCL for 1,2,4-Trichlorobenzene
(these last two cleanup standards are based on TBC criteria in the
absence of promulgated standards) to be met at the points of
compliance.
The total capital costs of this remedy are estimated at $3.1
million. The present worth cost of this remedy over thirty years is
estimated to.. be $8.3 million. The annual 0 & M costs are estimated
at $225,000.
41
-------
8.2
8.2.1
statutory Determinations
Protectiveness
The selected remedy is protective of human health and the
environment. Protection is achieved at this industrial site, and
in the aquifers extending beyond the Westinghouse property, in the
following ways:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
8.2.2
Groundwater will be restored to health-based standards for all
contaminated groundwater outside of the source area (the
source area is characterized by a dense, non-aqueous phase
liquid), thus preventing potential exposures, should these
shallow aquifers ever be used for water supply purposes.
Permanent hydraulic containment of the source area will
prevent pollutant migration and further contamination of the
shallow aquifers, which are potential drinking water supplies.
This containment will be combined with land use restrictions
to prevent construction of supply wells in the source area
where dense non-aqueous phase liquid has been detected.
The extracted groundwater will be treated, prior to onsite
discharge, to meet all ARARs identified for such discharges.
contaminated soil containing greater than 25 parts per million
PCB which represents a 10-6 risk in an industrial setting will
be removed to a depth of eight feet, thereby preventing
potential exposure at the surface, or in the subsurface (e.g.,
utility line workers).
The removed soil, spent filtration membranes and spent carbon
will be incinerated offsite, resulting in the destruction of
these contaminants and thereby preventing further possibility
of exposure to them.
Land use restrictions will prevent excavation, and therefore
exposure, in the area where contaminated soils remain at
depths greater than eight feet.
Land Ul;>f? 1;'estrictions will also prevent any residential
development in the source area, in order to further preclude
any risk of exposure due to contact with soil contamination.
Applicable or Relevant and Appropriate Requirements
Chemical-Specific ARARs - ARARs for the groundwater are the current
state or federal (whichever are more stringent) maximum contaminant
levels (MCLs) to be met in the affected aquifers (NCP, 40 C.F.R.
S300.430(e) (2) (i) (C). These relevant and appropriate requirements
are presented in Table 8. Included in Table 8 are two cleanup
standards that are based on TBC criteria in the absence of
42
-------
promulgated standards and they must also be met in the affected
aquifers. These are 1,3 Dichlorobenzene and 1,2,4-
Trichlorobenzene. Alternative C2 complies with these requirements
everywhere in the A and B aquifers with the exception of the A
aquifer source area, where EPA has determined that it is
technically impracticable to meet the MCL for PCB and has invoked
a waiver for this requirement pursuant to CERCLA S121(d) (4) (C) .
Permanent containment of this limited portion of the A aquifer,
which is discussed further in section 6.2.2.2 of this ROD, is
required. The technical impracticability waiver of the relevant
and appropriate PCB MCL is based upon the presence of spatially
discontinuous, dense, non-aqueous phase liquid (PCB Aroclor 1260)
in significant amounts; the heterogeneity of the subsurface
combined with low permeabilities; and the characteristics of PCB
(low solubility," high tendency to partition onto organic materials
and high viscosity).
ARARs for soil cleanup levels have not been established. However,
a 25 ppm soil cleanup level for PCB contaminated soils at
industrial sites is consistent with Guidance on Remedial Actions
For Superfund sites With PCB contamination, OSWER Directive No.
9355.4-01, August 1990, which is a TBC criteria. The selected
remedy complies with the 25 ppm soil cleanup level from the surface
to a depth of eight feet. .
Action-Specific ARARs - The substantive discharge standards under
the Clean Water Act are applicable requirements for discharge of
any effluent from the groundwater treatment system to the storm
sewers. The substantive discharge requirements .under the
California Porter-Cologne Act also apply to such discharges. The
selected remedy requires compliance with these applicable
requirements.
The California Regional Water Quality Control Board's Basin Plan is
also an ARAR, including the State of California's "Statement of
Policy With Respect to Maintaining High Quality of Waters in
california, II. Resolution 68-16, incorporated therein. The selected
remedy requires compliance with these applicable requirements,
which deal with maintenance of high quality waters in California.
certain ARARs are applicable to the various components of the
extracted groundwater treatment system. If granular activated
carbon adsorption is implemented as part of the treatment process,
Subpart D of TSCA is an ARAR for the storage and treatment of spent
carbon. The same requirement is an ARAR for spent filtration
membranes if they are included in the treatment process. If ozone
is used for the ultraviolet-chemical oxidation process, or if an
air stripper is added to the process train, Bay Area Air Management
District's Regulation 8, Rule 47 is an ARAR for air emissions from
either of these treatment process components. The selected remedy
requires compliance with these applicable requirements.
43
-------
The Bay Area Air Management District I s Regulation 8, Rule 40, which
deals with contaminant air emissions during excavation is an ARAR
for the selected remedy, which employs excavation as a component of
the remedy. The selected remedy requires compliance wi th this
applicable requirement.
subpart D of TSCA, which specifies treatment, storage, and disposal
requirements for PCB, applies to excavated site soils. The
selected remedy requires excavation and short-term storage of
excavated soils. The selected remedy requires compliance with the
TSCA treatment requirements and those requirements concerning
storage, all of which are applic~le.
The storage requirements for soi~s containing greater than 50 ppm
PCB found in C.C.R. Title 26, 522-66371 and 522-66508 are ARAR for
the storage of hazardous wastes at the site. The selected remedy,
which includes excavation of soils, requires compliance with these
applicable requirements.
It should be noted that RCRA is not an ARAR for the treatment
storage or disposal of the Westinghouse soils because PCB is nota
RCRA waste and no RCRA wastes are mixed with the PCB-contaminated
soils. Nor does EPA believe the situation at this site is
sufficiently similar to that addressed by these RCRA requirements
to justify a determination that they are relevant and appropriate
to this cleanup.
Location-Specific ARARs - There have been no location-specific
requirements identified that are ARARs for the cleanup of the
Westinghouse site.
8.2.3
Cost Effectiveness
The remedy is cost effective because maximum protection is achieved
for the estimated cost of performance. The comparative analysis
of the alternatives (see Section 7.7 of this ROD) demonstrates that
additional remedial action and the cost associated with that action
would not achieve a measurable reduction in risk, but that less
effort and a lower cost would r.esult in a measurably higher risk at
the site.
8.2.4
Use of Permanent Solutions, Alternative Treatment or
Resource Recovery Technologies to the Maximum Extent
Practicable .
The selected remedy, which combines containment and treatment
components, requires cleanup which allows for continued industrial
use of this site. In the absence of a technically practicable
technology for treating or removing the DNAPL contamination in the
A aquifer, this area of the aquifer will be permanently contained.
The containment method is hydraulic control, i.e., extraction, and
44
-------
the extracted groundwater will be treated using technologies that
result in destruction of the contaminants. Outside of the source
area, both the A and B aquifers will be restored to the MCLs, the
CDHS Action Level for 1,3-Dichlorobenzene and the proposed MCL for
1,2, 4-Tr ichlorobenzene through extraction. All extracted
groundwater will be treated by the same treatment system.
Among the options considered for addressing contaminated soils, the
best balance of the nine criteria set forth in the NCP is achieved
by the selected remedy. Soils which do not represent a principal
threat due to their location at depths greater than eight feet arid
their inability to significantly affect groundwater are left in
place. Eight feet of clean fill soil, an asphalt cap and land use
restrictions further prevent potential contact with these soils.
Temporary subsurface work in the upper eight feet in the clean fill
areas is permitted under the land use restrictions, but complete
restoration of the fill material and asphalt cap will be required
once any work is completed. Deeper excavation and soil removal
does not reduce the risk measurably, but costs much more. Capping,
with no soil removal, (containment only), is significantly less
expensive, but there is a much higher risk in relying entirely on
land use restrictions and fencing to prevent any potential exposure
to the principal threat soils below the cap.
Incineration has been selected over land disposal for the excavated
soils. This decision to select a significantly more expensive
option is based upon the strong statutory preference for treatment.
Additionally, these soils are classified as principal threat soils
and there is .an expectation that such wastes will be treated rather...
than land disposed wherever practicable (see NCP, 40 C.F.R.
S300.430(a) (1) (iii».
The selection of the treatment technologies for soil and
groundwater discussed above demonstrate that, where it is
practicable, the selected remedy will include permanent solutions.
However, because removal or treatment of dense non-aqueous phase
liquids at this site has been determined to be technically
impracticable, the remedy requires long-term containment of the
source area. Because this remedy will resul t in hazardous
substances remaining on-site above health-based levels, a review
will be conducted within five years after commencement of the
remedial action, and every five years thereafter, to ensure that
the remedy continues to provide adequate protection of human health
and the environment.
8.2.5
Preference for Treatment as a Principal Element
Soil containing greater than 25 parts per million PCB will be
excavated to a depth of eight feet and incinerated offsite,
reducing the toxicity, mobility and volume of site contamination by
permanently destroying the PCBs in the excavated soils with a
45
-------
treatment technology.
Toxicity, mobility and. volume of groundwater contaminants will also
be reduced as extracted groundwater is treated, by the combination
of phase separation (product phase will be incinerated), filtration
(filters will be incinerated) and ozone oxidation (chemical
destruction) steps.
The selection of these treatment technologies as an integral part
of the cleanup plan for both soil and groundwater demonstrates that
the cleanup plan satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume as
a principal element.
46
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TClble 1-
Scenario 1
Worker E:=xposure: Ingestion of Chemicals in Soil
Equation:
Ab ........... do .....,./I,...~...) CS x ASS x INGR x CF x FI x EF x ED
SOI~ se (..~~..",ay = BW x AT
where: CS = chemical concentration in soil (mgIkg)
ABS = absorption fraction (unitless)
INGR = ingestion rate (mg soil/day
CF .. conversion factor (10~ kgIrng)
FI = fraction ingested from contaminated source (unitless) ~
EF = exposure frequency (daySlyears)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (period over which exposure is averaged - days)
;
Variable Case Receptor Value (Rationale/Source)
CS RME Wol1
-------
Table d...
Scenario 1
Worker Exposure"!: Oermai Contact with CtlemicalS in Soil
Equation: .
Absorbed dose (mglkg-da ) - CS x ASS x CF x SA x AF x EF x EO
Y - BWxAT
where: CS = chemical concentration in soil (mgIkg)
ABS = absorption fradion (unit less)
CF = conversion fador (1~ kglmg)
SA 8: skin surtace area available for contad (cm2/event)
AF = soil-to-skin adherence fador (mglcm2)
EF .. exposure frequency (dayslyears)
ED = exposure duration (years)
BW = body weight (kg)
AT . averaging time (period over which exposure is averaged - days)
Variable Case Receptor Value (Rationale/Source)
CS RME Workers (all) 95% confidence interval of mean concen-
trations in soil (EPA. 1989a)
Typical Workers (all) Arithmetic mean concentrations in soil
(EPA.1989a) ,
ABS RMEJTypical Workers (all) 0.1 PCBs (EPA. 1990a): DCB. TCB (0.25:
see text Sedion 8.5)
SA RMEJTypical Workers (all) 3,200 cm2 (harods and arms; surface
area: EPA. 1989c)
AF RME Workers (all) 1.5 mgIcm2 (EPA. 1984)
;.
Typical Workers (all) 0.5 mgIcm2 (EPA. 1984)
EF RME Subsurtace 0.6 day/year (3 days every 5 years)
worker
Surtace 50 days/year
. worker
Typical Subsurtace 0.2 day/year (1 day every 5 years)
worker
Surtace 6 dayslyear
worker
ED RME Workers (all) 30 years (EPA. 1989c)
Typical Workers (all) 9 years (average length of employment at
facility)
BW RMElTypical Workers (all) 70 kg (average: EPA. 1989c)
AT RMElTypical Workers (all) Pathway-specific period of exposure for
noncarcinogenic effedS (Le.. ED x 365
dayslyear), and 70-year lifetime for car-
cinogenic effeds (i.e.. 70 years x 365
days/year) .
PJB B510S01A.GOW
Rev.O May 28. 1991
-------
Table 9
Scenario 2
Residential Exposure: Ingestion of Chemicals in Soil
Equation: .
Absorbed dose (rngI1cg-day) -
CS x ASS x INGR x CF x FI x EF x EO
BW x AT
= chemical concentration in soil (mgIkg)
= absorption fraction (unitless)
:& ingestion rate (mg soiVday
= conversion fador (10~ kgImg)
- fraction ingested from contaminated source (unit less) .
= exposure frequency (daySlyears)
= exposure duration (years)
= body weight (kg)
= averaging time (period over which exposure is averaged - days)
where: CS
ABS
INGR
CF
FI
EF
EO
BW
AT
".
Variable Case Receptor Value (Rationale/Source)
CS RME All 95% confidence interval of mean concen-
tratior.s in' soil (EPA. 1989a)
Typical All Arithmetic mean c;oncentration (EPA.
1989a)
ASS RMElTypical AU 0.3 PCBs (EPA. 1990a). 1.0 other
chemicals
INGR RMElTypical Adults 100 mgfday (age groups greater than
6 years old; EP A. 1989d)
--
.RMElTypical Children 200 mgfday (children 1 through 6 years
old; EPA. 1989d)
FI RMElTypical All 1.0 (assumed)
EF RME/Typical All 365 daySlyear (assumed)
.
EO RME Adults 30 ye2rs (90th percentile time at one resi-
. dence: EPA. 1989c)
Typical Adults 9 years (median time at one residence;
EPA, 1989c)
RMElTypical Children 6 years (EPA. 1991b)
BW AME All Median body weight for each respective
~ age group (70 kg adult male. 16 kg child:
EPA, 1989c. 1991a)
AT AME All Pathway-specific period of exposure for
noncarcinogenic effects (i.e.. EO x 365
dayS/year). and 7o-year lifetime for car-
cinogenic effects (i.e.. 70 years x 365
dayS/year)
PJB B5108C1A.GOW
Rev. 0 May 28. 1991
-------
Table i/
Scenario 2
Residential Exposure: DennaJ Contact with Chem~1S in Soil
where: CS
ASS
CF
SA
AF
EF
EO
aw
AT
Equation:
Absorbed dose (mgIk"'-day) CS x ASS x CF x SA x AF x EF x EO
~ = BW x AT
= chemical concentration in soil (mgIkg)
= absorption fraction (unit less)
= conversion factor (10~ kglmg)
= Skin surface area available for contact (cm2/event)
= soil-to-Skin adherence factor (mglcm2)
= exposure frequency (daySlyears)
= exposure duration (years) .
= body weight (kg)
= averaging time (period over which exposure is averaged - days)
Variable Case Receptor Value (Rationale/Source)
CS RME All 95% confidence interval of mean concen-
trations in soil (EPA, 1989a)
I Typical All Arithmetic 'mean concentrations in soil
(EPA, 1989a)
ASS RME/Typical All 0.1 for PCBs (EP~ 1990a); 0.25 for DCB
and TCa (see text Section 8.5)
SA RME/Typical Adults 4,600 crr(1. (hands, forearms, and one-half
legs; surface area; EPA, 1989c)
RME/Typical Child 1,800 crr(1. (hands and one-half arms and
legs: surface areas; EPA, 1989b)
AF RME All 1.5 mgtcm2 (EPA, 1984) ::
Typical AU 0.5 mgtcm2 (EPA, 1984)
EF RME/Typical All 365 daySlyear (assumed)
EO RME Adults 30 years (national u~r bound time [90th
percentile] at one resIdence: EPA, 1989c)
Typical Adults 9 years (median national time at one resi-
dence; EPA, 1989c)
RME/Typical Children 6 years (EPA, 1991b)
BW RME/Typical All Median body weights for each respective
a~e group (70 kg adult male, 16 kg child:
E A, 1989c and 1991a)
AT RME/Typical All Pathway-specific period of exposure for
noncarcinogenic effects (i.e., EO x 365
daySlyear). and 70-year lifetime for car-
cinogenic effects (i.e.. 70 years x 365
days/year)
PJ8 8510801A.GOW
Rev. 0 May 28. 1991
-------
Tab!e 5
Scenario 2
Residential ExP9sure: Ingestion of Chemicals in Drinking Water
(and Beverages Made Using Drinking Water)
where: CW
FI
ASS
IR
EF
ED
BW
AT
Equation:
Intake (mglkg-d ) - CW x FI x ASS x IR x EF x ED
ay - BWxAT
= Chemical concentration in soil (~)
= fradion ingested from source (unltless, assumed to be 1)
= fraction absorbed (unit less. assumed to be 1)
= ingestion rate (Vday)
= exposure frequency (dayslyears)
= exposure duration (years)
= body weight (kg)
= averaging time (period over which exposure is averaged - days)
Variable Case Receptor Value (Rationale/Source)
CW RME All Maximum concentrations in ground water
I (EPA,1989a)
Typical All I Arithmetic meim concentration in ground
water (E?A, 1989a)
FI
ASS RME/Typical "All 1 (by convention; EPA. 1989b)
IR RME/Typical Adult 211day (EPA, 1991a)
0"
RME/Typical Child 111day (EPA. 1991a)
EF RME/Typical All 365 dayslyear (EPA. 1989b)
ED RME Adults 30 years (90th percentile time spent at
. one residence; EPA, 1989a)
Typical Adults 9 years (median time spent at one
, residence; EPA, 1989a)
RME/Typical Children 6 years (EPA, 1991b)
BW RME/Typical Adult 70 kg (EPA. 1989a, 1990b)
RME/Typical Child 16 kg (:ypical value co"esponding to
body weight of 4-year-old; EPA, 1991a)
AT . RME/Typical All Pathway-specifIC period of exposure for
noncarcinogenic effeds (i.e., ED x 365
daySlyear), and 70-year lifetime for car-
cinogenic effects (i.e., 70 years x 365
daySlyear)
?J8 eS10801A.GOW
Rev. 0 May 28, 1991
-------
Table fe.
Summary of Estimated Carcinogenic and Noncarcinogenic Risks
at the Westinghouse Site
Typical Exposure
Scenario
Ground-Water Exoosure
Aquifer A
Adult Male Resident
Ingestion
Inhalation/dermal
TOTAL
1- to 6-vear-okJ Child Resident
Ingestion
Inhalation/dermal
TOTAL
Aquifer B1
Adult Mate Residents
Ingestion
Inhalation/dermal
TOTAL
1- to 6-vear-old Child Resident
Ingestion
Inhalation/dermal
TOTAL
Sol! Exoosure -
Adult Male Resident
Ingestion
Dermal
TOTAL
1- to 6-vear-old Child Resident
Ingestion
Dermal
TOTAL
Surface Worker
Ingestion
Dermal
TOTAL
Subsurface Worker
Ingestion
Dermal
TOTAL
Cancer Risk
5.25E-03
1.35E-05
5.26E-03
7.54E-03
1.45E-05
7.65E-03
1.87E-05
1.05E-07
1.88E-05
2.72E-05
1.53E-07
2.73E-05
7.62E-02
1.67E-OI
2.43E-01
1.29E-01
4.64E-01
5.93E-01 :
6.01 E-04
3.20E-03
3.80E-03
1.82E-07
9.78E-07
1.16E-06
Hazard Index
5.95E400
2.59E+00
8.54E-»00
1.29E+C1
5.66E+00
1.86E-fQ1
3.24E-02
9.44E-02
1.27E-01
7.11E-02
2.07E-01
2.78E-01
1.12E-02
1.94E-01
2.05E-01
9.85E-02
3.32E-01
4.31 E-01
2.90E-04
1.16E-Q3
1.45E-03
8.70E-07
3.49E-06
4.36E-06 '
RME Scenario
Cancer Risk
5.15E-02
9.82E-05
5.16E-02
2.31 E-02
4.28E-05
2.31 E-02
9.80E-05
9.34E-07
9.89E-05
4.29E-05
4.09E-07
4.33E-05
1.19E-01
9.46E-01
1.00E+00
2.00E-01
6.32E-01
8.32E-01 '
2.55E-02
3.38E-01
3.64E-01
4.37E-06
6.99E-05
7.43E-05
Hazard Index
1.80E+01
7.90E+00
2.59E+01
3.94E+01
1.73E+01
5.67E-r01
8.08E-02
2.41 E-01
, 322E-01
1.77E-01
5^8E-01
7.05E-01
2.44E-02
4.21 E-01
4.45E-01
2.14E-01
7.21 E-01
9.35E-01
1.08E-01
1.08E-01
1.17E-01
7.63E-06
9.16E-05
9.92E-05
PJB B510801A.GOW
Rev. 0 May 28.1991
-------
.,
TABLE 7
Remedial Alternatives
live C Alternative D
8 ft Excavation to 32 ft.
I or treatment Offslte di~osal or treatment
ndwater Capping! round water
Containment
.rs at surface . Prolects workers at surface
ace and in subsurface
onlalnment . Groundwater conlalnment
gradient aquifers protects downgradient aquifers
all require. . Complies wilh all rcquire.
drinking waler menls excepl drinking waler
PCB Standards for PCB
C2 Trealmenl 01 Disposal 02 Treatmenl
. Treatment . No TMV . Treatmenl
of soils through treal. of soils
reduces TMV menl with reduces
disposal of soil TMV
bJ. Treating . Reduces TMV bJ Trei.ling
n waler exlracted groun water
lIess manage. . Solis In source area removed
when 8 (I. o( r.ompletely bUI still relies on
long term pump and !/,ut
nstilutional con. control of groundwater
lerm pumping
for soils . Some dirficulty for soils
option with trealment (C2) oplion wilh
orl, trcatmenl storagc, transport, treatment
'C2 01 02
-
53,114,000 52,691,000 57,733,000
522 5, ()(j() S225,f)()O S225,OOO
$8,26 J,OOO $7,840,000 512,882.000
-
Alternative A Alternative B
No Action No Excavation
Cappl~ II
Groun water Containment
Protects Health . No rcdudion in risk . Protects workers at surface but
and Environment . POlcnllal waler supplies not in subsurface
..Groundwater containment
threatened protects downgradlent aquifers
Complies wi Ih . Docs not comply . CClmplies with all rc~uire.
Federal, Slate, Local ments except drinking water
Requirements Star.dards for PCB
Reduces Toxicity, . No reduction in TMV . Reduces TMV bJ Treating C1 Dis;>oul
Mobility and Volume extracted groun water . No TMV
. No TMV for solis through treat.
(TMV) Through ment with
Treatment disposal of soli
. Reduces TMV
extracted grou
E'ffectiveness . Not effective . Institutional controls and long
term man~ement of lioils
and groun water in source
area
Implementability . Easily implemenled . E~sily implemenled
COSTS C'I
Capital $ 62,000 $ 1 ,325,000 $1,725,000
Annual 0 & M 5 J 58,000 5225,000 5225,000
Present Worlh $3,744,000 ~6,474,000 S6,674,~O
Alterna
Excavation to
Offslte dispo!ia
Capping/Grou
Conlainment
. Prolectl work!!
and in subsur(
. Groundwater c
protects riown
. Complies with
menls excepl
Standards for
. More erfedive
ment required
soil removed
.51111 relics on j
trois and long
. Some dHficulty
Irealment (C2)
storage, transp
'I'.
-------
1.
2.
3.
4.
5
TABLE 8
Groundwater Cleanup criteria
ppbl
Chemical Name
standard
Benzene
12
6003
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1304
52
1,4-Dichlorobenzene
1,1-Dichloroethane
52
0.52
1,2-Dichlcroethane
1,1-Dichloroethene
ciS-l,2-Dichloroethene
62
62
Ethylbenzene
6802
302
Monochlorobenzene
Polychlorinated biphenyls
0.56
10003
Toluene
1,2,4-Trichlorobenzene
55
2003
1,1,1-Trichloroethane
Trichloroethene
53
17502
Xylene(s)
6.
ppb = parts per billion
state Maximum contaminant Level (MCL)
Federal Maximum Contaminant Level (MCL)
state Department of Health Services Action Level
Proposed Federal Maximum Conataminant Level, expected
promulgated March 1992
Promulgated Federal MCL, effective July 1992
to be
-------
...
Table 9
Carcinogenic Aisks and Hazard Quotients of Injesting Ground-Water
with Concentrations at Water Quality Criteria
Maximum Contaminant Highest Chronic Cancer Hazard
Levels IMQls) Delecled Calculated Reference Potency Chemical Quotient
Concentration Ingestion Dose. (c) Factor (c) Specific lor Non-
EPA State at site (a) Aate (b) (Afd) (slope factor) Cancer carcinogens
COMPOUND (~g/I) (~g/I) (ltg/I) II(mglkg.day) (mglkg-day) (mglkg-day)-1 Risk (d) (e)
VOLATilE ORGANICS'
Benzene 5 1 1.22E-05 NA 2.9E-02 3.6E-07
Chlorobenzene 100 30 9.6 2.74E-04 2.0E-02. NA 1.4E-02
1,2.DichlorObenzene 600 174 4.97E-03 9.0E.02 NA 5.5E.02
1.3-Dichlorobenzene 130 (f) 120 3.43E-03 NA NA
1,4-Dichlorobenzene 75 5 6.12E-OS NA 2.4E-02
1 .1 -Oichloroethane 5 1.2 1.47E.OS 1.0E-01 1.5E-04
1,2-0ichloroethane 5 O.S 6.12E-06 NA 9.1E-02 S.6E-07
1.1.Dichloroethene 7 6 5 6.12E.OS 9.0E-03 6.0E -01 3.7E.OS 6.8E-03
cis-1.2-0ichloroethene 70 6 2 5.71E-05 1.0E-02 NA S.7E-03
Ethylbenzene . 700 BO 330 9.43E-03 1.0E.01 NA ...- 9.4E.02
Polychlorinated biphenyl O.S 6.12E-06 N:.\ . 7.7E+OO 4.7E-05
Toluene 1.000 100 1.22E-03 2.0E-02 NA 6.1E-02
1.2.4- Trichlorobenzene 9 1.10E.04 1.3E-03 NA 8.4E-02
1.1,1- Trichloroethane 200 20:> 22 6.29E-04 9.0E-02 NA 7.0e-03
T richloroelhene 5 5 6.12E.05 NA 1.1E-02 6.7E-07
Xylene(s) 10,000 1,750 9B7 2.82E-02 2.0E+OO NA 1.4E-02
Totat RIsk (a) B.SE-OS
Hazard tndex (h) 3.4E-01
(a) Only Ii~ted for those site COCs at concentrations less than federal or state water quaHty criteria.
(b) Assumes that concentration of compound in drinking water matches, state or federal MCl. DHS Action level, or highest
detected concentration (oSee section 8, table 8.S-5 for equation).
(c) From Health Effects Assessment Summary Tables (HEAST). Four Quarter FY - 1990
(d) Chemical-specific cancer risk calculated by multiplying injestion by slope factor
(e) Chemical hazard Index calculated by dividir,g injestion by relerence dose
(ij DHS Action level
(g) Tolal risk calculated by summing chemical.specific cancer risk
(h) Hazard Indes calculated by summing chemical-specific hazard quotients
Blank space: No existing value. .
-------
Table 10
Sensitivity Analysis Summary
Cost Low DiHerence % Less . Median DiHerence % Greater High
Than Median Than Median
Capilal Cost $78,000
A $1\ 7 ,OCO $15.000 24% $62,000 $16,000 26%
a $1.210.000 $115.000 9% $1,325,000 $161,000 12% $1,486,000
C1 $1.610.000 $115.000 7% $1.725,000 $161.000 9% $1,886.000
C2 $2.999.000 $115.000 4% $3,114.000 $161,000 5% $3,275,000
01 $2.576.000 $115.000 4% $2,691,000 $161,000 6% $2.852,000 .
02 $7.618,000 $115.000 1% $7,733,000 $161,000 2% $7,894,QOO
O&M COSI,
Year 1
A $370.000 $20.000 5% $390,000 $19,000 5% $409,000
a.c,o $435,000 $23.000 5% $458,000 $24,000 5% $482,000
O&M Cosi.
Year 2
A $150.000 $8,000 5% $158,000 $8.000 5% $166,000
a.c.o $214,000 $11.000 5% $225,000 $13,000 6% $238,000
Present Worth
A $3.543.000 $201.000 5% $3,744.000 $202,000 5% $3,946,000
a $6,106,000 $368,000 6% $6,474,000 $456,000 7% $6,930,000
C1 $6.506.000 $368,000 5% $6,874,000 $456,000 7%' $7,330,000
C2 $7,895,000 $368,000 4% $8,263,000 $456,000 6% $8.719,000
01 $7,472,000 $368,000 5% $7,840,000 $456,000 6% $8,296,000
02 $12,514,000 $368,000 3% $12,882,000 ' $456,000 4% $13.338,000
Low=20% less, Medianabase case, High=20% more
Ground-water extraction system variables: number and location 01 wells, soil disposal, pumps
Ground-water treatment system variables: design flow rate, O&M lor alternate flow rates
Ground-water monitoring system variables: number of wells, O&M
------- |