United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R09-91/063
September 1991
Superfund
Record of Decision:
Van Waters & Rogers, CA
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50272-101
REPORT DOCUMENTATION /'. REPORTNO.
PAGE EPA/ROD/R09-91/063
I ~
3. Reciplenta Acceuion No.
.. TItI8 end SW>tIOe
SUPERFUND RECORD OF DECISION
Van Waters & Rogers, CA
First Remedial Action - Final
7. Authoria)
50 Report Date
09/11/91
6.
8. Perfonnlng Organization Rept. No.
8. f/Ierfonnlng Orgalnlza1lon Name and Addre88
10. Project/TuklWork Unit No.
11. Contnc:t(C) or Gr8nt(G) No.
(C)
(G)
12. SponeorIng OrgaU8tlon Name and ~
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report" Period Covered
Agency
800/000
14.
15. Supplement8ry No-
16. Abetract (Umlt: 200 -rd8)
The 13.7-acre Van Waters & Rogers site is a commercial chemical storage, handling,
and distribution facility in San Jose, California. Land use in the area is
predominantly commercial and industrial. Nearby surface drainage features include
Coyote Creek, approximately 1,200 feet to the east, and the Guadalupe River,
approximately 6,000 feet to the west, that discharge to San Francisco Bay 9 miles to
the north. Since 1976, Van Waters & Rogers has used the site for bulk chemical
transfers; storage in drums and underground tanks; chemical blending, packaging, and
distribution; and rinsing of containers. Surface features from which releases of
organic chemicals have occurred are above-ground storage tanks, rail-mounted tank
cars, drum fillers, underground storage tank (UST) fill pipe manifolds, and a
hazardous waste storage area. Subsurface features include 37 USTs; subsurface
product transfer piping; and the subsurface storm drain system, which eventually
discharges to the Guadalupe River. Fourteen USTs are not in service and are
currently empty. With the exception of one tank used to store diesel fuel, all USTs
have been used to store various industrial chemicals including PCE, toluene, and
xylenes. During a survey of regional hazardous waste facilities in 1982, the State
(See Attached Page)
17. Document An8/y8I8 L De8c:riptora
Record of Decision - Van Waters & Rogers, CA
First Remedial Action - Final
Contaminated Media: soil, debris, gw
Key Contaminants: VOCs (PCE, TCE)
b. IdentifierelOpen-Ended Tenne
Co COSAn AeIdIOroup
ilL 18. Avlilabilty St8I8ment
19. Security Clua (ThIa Report)
None
20. Security Clua (Thla Page)
Nnnp
21. No. of Pagea
48
22. PrIce
(See ANSl-Z39.18)
See /II81TUCri0M on Rswtae
272 (4-n)
(FOITIIefIy NTI~35)
Department o' Commerce
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EPA/ROD/R09-91/063
Van Waters & Rogers, CA
First Remedial Action - Final
Abstract (Continued)
identified VOCs, selected aliphatic hydrocarbons, aromatic hydrocarbons, ketones,
glycols, and alcohols in onsite soil and ground water. Potential sources of
contamination include a 1977 accidental release of PCE from an above-ground 12,OOO-gallon
tank at the loading dock and various leaks from USTs and associated piping. Van Waters &
Rogers began an interim ground water remediation program in 1986 that involves ground
water extraction and treatment using air stripping with onsite discharge to the storm
drain. This Record of Decision (ROD) provides a final remedy for onsite contaminated
soil, debris, and ground water. The primary contaminants of concern affecting the soil,
debris, and ground water are VOCs including PCE and TCE.
The selected remedial action for this site includes treating approximately 8,100 cubic
yards of soil "hot spots" containing more than 10 mg/kg of one or more of PCE, TCA, and
TCE using in-situ vapor extraction; temporarily capping 46,000 cubic yards of soil
containing greater than 1 mg/kg total VOCs, including areas containing USTs until tank
removal can take place; removing USTs at a later date and investigating adjacent soil;
expanding the existing upper aquifer ground water pumping and treatment system by adding
an air stripping unit and converting existing monitoring wells to extraction wells,
wherever possible; treating the off-gases from the new air stripping unit; treating the
lower aquifer by either granular activated carbon or air stripping; discharging the
treated ground water onsite to the storm drain system; monitoring soil and ground water;
and implementing institutional controls including deed restrictions. The estimated
present worth cost for this remedial action is $4,997,000, which includes a net present
value O&M cost of $4,374,000.
PERFORMANCE STANDARDS OR GOALS: Clean-up goals for soil are intended to minimize
contaminant migration to ground water. Chemical-specific initial soil goals for PCE and
TCE are 10 mg/kg. Final soi1 goals will be 1 mg/kg for total VOCs. Chemical-specific
ground water clean-up goals are based on State and Federal MCLs and risk levels, and
include PCE 5 ug/l (MCL) and TCE 5 ug/l (MCL).
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RECORD OF DECISION
VAN WATERS AND ROGERS
SUPERFUND SITE
SAN JOSE, CALIFORNIA
SEPTEMBER 11, 1991
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 9
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CONTENTS
PART SECTION PAGE
PART I; DECLARATION
I 1.0 Site Name and Location 1
I 2.0 Statement of Basis and Purpose i
I 3.0 Assessment of the Site 1
I 4.0 Description of the Remedy 1
I 5.0 Declaration 2
PART II; DECISION SUMMARY
II 1.0 Site Name, Location and Description 3
1.1 Site Name and Location 3
1.2 Regional Topography 3
1.3 Adjacent Land Use 3
1.4 Historical Land Use 4
1.5 Hydrogeology 4
1.6 Water Use 5
1.7 Soil and Subsurface Structures 5
II 2.0 site History and Enforcement Activities 6
2.1 History and Site Activities 6
2.2 History of Site Investigations 7
2.3 History of Enforcement Actions 7
II 3.0 Community Relations 8
II 4.0 Scope and Role of the Response Action 8
4.1 Scope of the Response Action 8
4.1.1 Interim Remedial Measure 8
4.1.2 Selected Remedy 9
4.2 Role of the Response Action 9
II 5.0 Summary of site Characteristics 9
5.1 Sources of Contamination 9
5.2 Description of Contamination 10
5.2.1 Subsurface Structures/Soil
Investigations 10
5.2.2 Groundwater Investigations 10
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CONTENTS (continued)
PART
II
II
II
II
II
SECTION
6.0
6.1
6.2
6.3
6.4
6.5
6.6
7.0
7.1
7.2
7.3
7.4
8.0
8.1
8.2
8.3
9.0
9.1
9.2
9.3
9.3.1
9.3.2
10.0
Summary of Site Risks
Toxicity Assessment
Exposure Assessment
Risk Characterization
Presence of Sensitive Human Populations
PAGE
11
12
12
13
14
Presence of Sensitive Ecological Systems 14
Conclusion 15
Applicable or Relevant and Appropriate
Requirements (ARARs) 15
Types of ARARs 16
Chemical-Specific ARARs 16
Action Specific ARARs 17
Location-Specific ARARs 18
Description of Alternatives 18
Remedial Action Objectives 18
Cleanup Standards 19
Remedial Action Alternatives 20
Comparative Analysis of Alternatives 22
Criteria 22
Analysis of Alternatives 23
Selected Remedy 27
Description of Selected Remedy 27
Basis of Selection 29
Statutory Determinations 31
III
APPENDIX A:
APPENDIX B:
PART III; RESPONSIVENESS SUMMARY
Responsiveness Summary
Administrative Record Index
Guidance Documents
32
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LIST OF FIGURES
FIGURE TITLE PAGE
1 Regional Map 3
2 Site and Vicinity Map 3
3 site Map 5
4 Total VOCs Soil Contamination (5 Feet) 10
5 Total VOCs Soil Contamination (10 Feet) 10
6 A-Aquifer PCE Contamination Plume 10
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LIST OF TABLES
TABLE TITLE PAGE
1 Chemicals of Concern at VW&R 11
2 Summary of Site Risks 13
3 Cleanup Standards for Chemicals of
Concern 19
4 Cleanup Standards and Associated Risks 19
5 Estimated Costs for Remedial Alternatives 26
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PART I. DECLARATION
1.0 SITE NAME AND LOCATION
Van Waters and Rogers, Inc.
2256 Junction Avenue
San Jose, California 95131
2.0 STATEMENT OF BASIS AND PURPOSE
This Record of Decision ("ROD") presents the selected remedial
actions for the Van Waters and Rogers Superfund site in San Jose,
California. This document was developed in accordance with the
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA) as amended by the Super fund Amendments and
Reauthorization Act of 1986 (SARA), 42 U.S.C. Section 9601 et.
seq.. and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan, 40 C.F.R. Section
300 et. seq.. ("NCP"). The attached Administrative Record Index
(Attachment) identifies the documents upon which the selection of
the remedial action is based. The State of California concurs with
the selected remedy.
3.0 ASSESSMENT OF THE SITE
Actual or threatened release of hazardous substances from this
site, if not addressed by implementing the response actions
selected in this ROD, may present an imminent and substantial en-
dangerment to public health, welfare or the environment.
4.0 DESCRIPTION OF THE REMEDY
The selected remedy for the VW&R site consists of:
o Capping of entire site
o Groundwater extraction and treatment for groundwater
cleanup
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o Soil vapor extraction and treatment for soil cleanup
o Removal of underground storage tanks and additional
investigation of soil around them. If additional
remediation is required, the soil vapor extraction
system will be expanded to include the tank area
o Shallow aquifer groundwater monitoring
o Deed restrictions
These remedial actions address the principal threats and principal
risks remaining at the site by removing and permanently destroying
the contaminants from soils and removing the contaminants from
ground water, thereby significantly reducing the toxicity, mobility
or volume of hazardous substances in both media. These response
actions will greatly reduce the possibility of contamination of
existing potable water supplies and potential future water
supplies.
5.0 DECLARATION
The selected remedy is protective of human health and the en-
vironment, complies with federal and state requirements that are
legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent
solutions and alternative treatment (or resource recovery) tech-
nologies to the maximum extent practicable and satisfies the
statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element.
Because the remedy will result in hazardous substances remaining
on-site above health-based levels, a five-year review, pursuant to
CERCLA Section 121, 42 U.S.C. Section 9621, will be conducted at
least once every five years after initiation of the remedial action
to ensure that the remedy continues to provide adequate protection
of human health and the environment.
John WiseV/ Date
Deputy Regional Administrator
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PART II. DECISION SUMMARY
This Decision Summary provides an overview of the problems posed
by the Van Waters & Rogers site ("VW&R" or "the site"), the
remedial alternatives, and the analysis of the remedial
alternatives. This Decision Summary explains the rationale for the
remedy selection and describes how the selected remedy satisfies
the statutory requirements.
1.0 SITE NAME, LOCATION, AMD DESCRIPTION
1.1 SITE NAME AND LOCATION
Van Waters and Rogers, Inc.
2256 Junction Avenue
San Jose, California 95131
1.2 REGIONAL TOPOGRAPHY
The VW&R site is located in the Santa Clara Valley, a gently-
sloping alluvial plain (Figure 1). Major topographic relief
features include the Diablo Range to the northeast and the Santa
Cruz and Gavilan Ranges to the southwest. Nearby surface drainage
features include Coyote Creek, approximately 1200 feet to the east
of the site, and the Guadalupe River, approximately 6000 feet to
the west.. Both of these drainage features discharge into San
Francisco Bay nine miles to the north.
1.3 ADJACENT LAND USE
The 13.7 acre VW&R facility is located in a zoned commercial/
industrial area, about three miles north of downtown San Jose
(Figure 2). Land use in the vicinity of the site includes road and
rail transportation corridors, light to heavy manufacturing
facilities, warehouse and distribution facilities, oil storage
facilities, riparian habitats, and agricultural plots. Land use
immediately adjacent to the site includes road and rail
transportation facilities; food products packaging and distribution
facilities; a consumer electronics warehouse/distribution facility;
a public utility yard; several small retail outlets; and vacant
lots.
The site is located within a triangle bounded by the Bayshore
Freeway (U.S. Highway 101) to the west, the Nimitz Freeway
(Interstate Highway 880) to the east, and Trimble Road/Montague
Expressway to the north. The Santa Clara County light rail
transportation corridor is located approximately 3000 feet to the
west of the site. San Jose International Airport is located
approximately two miles southwest of the site.
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SAN JOSE, CALifORNIA
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The nearest residential areas are a mobile home park about 1.5
miles to the northeast (on the east side of the Nimitz Freeway) and
an active farm approximately 2500 feet north of Trimble Road. A
vacant lot that was formerly an agricultural plot is located
immediately southeast of the site. The riparian habitats are those
associated with the Guadalupe River and Coyote Creek. To the east
of the site, on the west bank of Coyote Creek, is a large oil and
petroleum products storage facility.
1.4 HISTORICAL LAND USE
Northern San Jose was once a predominantly agricultural area, but
has been intensively developed over the last 10 to 15 years. The
land on which the Van Waters & Rogers site is located was used for
agricultural purposes until 1975, when the site was purchased and
developed by VW&R, Van Waters & Rogers, Inc., a wholly owned
subsidiary of Univar, has operated a facility at the site since
1976.
1.5 HYDROGEOLOGY
The Santa Clara Valley is a large structural depression in the
Central Coastal Range of California. The Valley is filled with
alluvial and fluvial deposits from the adjacent mountain ranges.
These deposits are up to 1500 feet in thickness. At the base of
the adjacent mountains, gently sloping alluvial fans of the basin
tributaries laterally merge to form an alluvial apron extending
into the interior of the basin.
The Santa Clara Valley groundwater basin in divided into two broad
areas: l) the forebay, and 2) the confined area, where the VW&R
facility is located. The forebay occurs along the elevated edges
of the basin where the basin receives its principal recharge. The
confined area is located in the flatter interior portion of the
basin and is stratified or divided into individual beds separated
by significant aguitards. The confined area is divided into the
upper and lower aquifer zones. The division is formed by an
extensive regional aguitard that occurs at depths ranging from
about 100 feet near the confined area's southern boundary to about
150 to 250 feet in the center of the confined area and beneath San
Francisco Bay. The thickness of this regional aguitard varies from
about 20 feet to over 100 feet.
Several aquifer systems occur in the upper aquifer zone separated
by aguitards which may be leaky or very tight. The lower aquifer
zone occurs beneath the practically impermeable regional aquitard.
The regional aquitard occurs at approximately 100 to 150 feet below
grade in the area of the VW&R site. Numerous individual aquifers
occur below the aquitard in the lower aquifer zone and all
groundwater in the lower aquifer is confined.
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The site and vicinity is underlain by a semi-perched, shallow
water-bearing zone of relatively low permeability silty clay and
clayey sand, referred to as the A-aquifer. A-aguifer water level
data have consistently indicated groundwater flow to the northwest.
The average depth at which groundwater is encountered is about ten
to 14 feet below grade; the bottom of the aquifer extends to
approximately 45 feet below grade. The A-aquifer has been divided,
according to soil type, into the A-l and A-2 zones. Observations
during A-aquifer tests have indicated that the hydraulic connection
between the A- and B-aquifers downgradient of the open dock area at
the site is limited.
The A-aquifer is underlain by the more permeable B-aquifer, which
consists of the B-l and B-2 zones; water level measurements on
wells completed in the B-l zone indicate groundwater flows to the
northwest. The average thickness of the B-l zone is estimated to
be about 28 feet. Based on stratigraphy encountered in some wells
and borings in the B-2 zone, it appears that the B-2 zone is
separated from the overlying B-l zone by a relatively thin stratum
of stiff, gray-brown, sandy or clayey silt. Pump tests in wells
along the northern site boundary have indicated that the saturated
thickness of the B-l- and B-2-zones is approximately 45 feet.
1.6 WATER USE
The nearest municipal water supply wells are in the Breeding Avenue
Well Field operated by the City of San Jose, about 2000 feet east-
southeast and hydraulically upgradient of the site. Other wells
are located to the north of Trimble Road, about 2500 feet to the
north of the site. The majority of the active water-producing
wells in the vicinity extract water from aquifers well beneath the
A- and B- aquifers. Although the Santa Clara Valley was
historically a predominantly agricultural area, no active or
inactive agricultural wells have been identified in the area
immediately downgradient from the site.
The mobile home park located 1.5 miles to the northeast of the VW&R
site is served by a municipal water supply system. The farm
residence and other agricultural holdings north of the site are
serviced by individual domestic water supply wells.
1.7 SURFACE AMD SUBSURFACE STRUCTURES
The most prominent feature of the 13.7 acre site is a large, single
story warehouse structure (Figure 3). The eastern side of the
warehouse features a covered dock and an open dock. The remainder
of the site is either paved or landscaped. Reinforced concrete
aprons adjoin the loading bays along the south side of the building
and the elevated, open dock on the east side of the warehouse.
Other prominent surface features include a rail spur along the
north side of warehouse building; a rail spur along the northern
site boundary; a 13,500-gallon capacity, aboveground hydrogen
peroxide storage tank surrounded by a concrete secondary
containment wall; a truck scale; a groundwater treatment system;
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and a portable office trailer. The portion of the site in which
commercial operations are concentrated is fenced and is accessed
via two gates.
Surface features from which releases of organic chemicals to the
surface and/or subsurface environment could potentially have
occurred include aboveqround storage tanks, rail-mounted tank cars,
the drum fillers, the underqround storage tank fill pipe manifolds,
and the hazardous waste storage area. Subsurface features include
underqround storage tanks, subsurface product transfer piping, and
the subsurface storm drain system.
The facility contains 37 underqround storage tanks with capacities
of 6000- and 10, OOO-gallons. All but one of the underqround
storage tanks are located beneath the elevated open dock. The
remaining tank, which stores diesel fuel, is located beneath the
concrete truck apron near the ramp leading to the open dock.
Subsurface product transfer piping for the 36 chemical storage
tanks is. located beneath the open dock. In general, the subsurface
product transfer pipes run from the two manifolds on the eastern
edge of the open dock to the 36 underqround chemical storage tanks,
and then to the main manifold near the drum filling station.
Product transfers are achieved using portable, aboveqround pumps.
Other underground product transfer pipes are associated with the
underqround diesel fuel storage tank and the aboveground hydrogen
peroxide storage tank. The subsurface piping associated with the
diesel tank runs from the. tank to the nearby dispenser island, a
distance less than 10 feet. The subsurface piping associated with
the hydrogen peroxide tank runs from the tank to the open dock
area.
The on-site storm drain system consists of a subsurface. concrete
pipe served by five on-site inlet boxes. There are two ~dditional
inlet boxes within the 15-foot railroad easement. The most
easterly of these receives the effluent from the groundwater
treatment system. The storm drain system eventually discharges to
the. Guadalupe River, immediately downstream of the Montague
Expressway overpass.
Runoff from chemical storage/handling areas is prevented from
entering the storm drain inlets near the concrete apron by concrete
berms around the drain inlets.
2.0
SITB HISTORY AND BHPORCEHBNT ACTIVITIBS
2.1
HISTORY OF SITB ACTIVITIBS
VW&R is a commercial chemical storage, handling and distribution
facility that has been in operation since 1976. Principal
operations and activities at the site include bulk chemical
transfers between tank trucks, railroad tank cars, and underground
storage tanks; chemical storage in drums and underground tanks;
chemical blending, packaging, and distribution; and rinsing of
containers.
6
. .
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Fourteen of the underground storage tanks have been taken out of
service and are currently empty. With the exception of one tank
used for diesel fuel storage, VW&R presently uses, or has used in
the past the tanks to store the following industrial chemicals:
1,1,1-trichloroethane (TCA), methylene chloride,
tetrachloroethylene (PCE), selected aliphatic hydrocarbons,
aromatic hydrocarbons (including xylene and toluene), ketones,
glycols, and alcohols.
2.2 HISTORY OF SITE INVESTIGATIONS
Subsurface investigations at the VW&R site began in December 1982,
following the California Regional Water Quality Control Board
(RWQCB) survey of facilities in the San Francisco Bay Region known
to handle hazardous materials and waste. Site investigations have
been performed in phases by several consultants for VW&R since then
under orders from the RWQCB.
Subsurface investigations initiated at the site in December 1982
revealed the presence of various industrial chemicals in the soil
and groundwater at the facility. These chemicals included TCA,
trichloroethylene (TCE), PCE, 1,1-dichloroethane (DCA), 1,1- and
1,2-dichloroethylene (DCE), methylene chloride, vinyl chloride,
toluene, xylene, ketones, and alcohol. The highest concentrations
are located north of the open dock, the area where most chemical
handling has occurred.
2.3 HISTORY OF ENFORCEMENT ACTIONS
On October 2, 1984, the Environmental Protection Agency (EPA)
proposed adding the VW&R site to the National Priorities List
(NPL), subject to regulation under the Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA). Amendments to
the Resource Conservation and Recovery Act (RCRA) by the Hazardous
and Solid Waste Amendments (HSWA) of 1984 greatly expanded RCRA
corrective action authorities. Pursuant to HSWA, EPA dropped the
VW&R site from the list of proposed NPL sites in October 1989. As
a RCRA Storage Facility, VW&R is subject to the corrective action
authorities of Subtitle C of RCRA.
Under the South Bay Multi-Site Cooperative Agreement between EPA
and the RWQCB, the RWQCB has been acting as the lead regulatory
agency for this site. The following orders and permits have been
adopted or issued for the VW&R site:
o Site Cleanup Requirements Order No. 85-87, adopted
July 17, 1985
o Bay Area Air Quality Management District (BAAQMD)
operating permit No. 31053, issued February 13, 1986
o Waste Discharge Requirements Order No. 87-6 (NPDES
No. CA0028991), adopted February 18, 1987
o Site Cleanup Requirements Order No. 89-018 (rescinding
Order No. 85-87), adopted January 18, 1989
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3.0 COMMUNITY RELATIONS
The RWQCB has maintained an aggressive Community Relations program
for the VW&R site. The RWQCB published a notice in the July 10,
1991 and July 17, 1991 issues of the San Jose Mercury News
announcing the proposed final Remedial Action Plan and opportunity
for public comment at the RWQCB Hearing of July 17, 1991 in
Oakland, California, and announcing the opportunity for public
comment at an evening community meeting at City Hall in San Jose on
July 18, 1991. No members of the public attended the meeting. A
presentation of the proposed final cleanup plan was made at the
July 17, 1991 RWQCB Hearing. The 30-day comment period was from
July 17, 1991 until August 16, 1991.
Fact sheets were mailed to interested residents, local government
officials, and media representatives. Fact Sheet 1, mailed in
December 1989, summarized the pollution problem, the results of
investigations to date, and the interim remedial actions. Fact
Sheet 2, mailed in July 1991, described the cleanup alternatives
that were evaluated and explained the Proposed Plan for final site
remedial actions. It also announced opportunities for public
comment at the Board Hearing of July 17, 1991 in Oakland and at the
Public Meeting of July 18, 1991 in San Jose and described the
availability of further information at the Information Repository
at the City of San Jose Public Library. The Responsiveness Summary
summarizes responses to significant comments received during the
public comment period. Fact Sheet 3, to be mailed in September
1991, will explain the final cleanup plan adopted by the RWQCB.
4.0 SCOPE AND ROLE OF THE RESPONSE ACTION
4.1 SCOPE OF THE RESPONSE ACTION
The remedy selected and described in this ROD includes continuation
and expansion of existing interim remedial actions as well as
additional remedial actions selected for the VW&R site.
4.1.1 INTERIM REMEDIAL MEASURES
VW&R began an interim groundwater remediation program in December
1986. The program currently includes groundwater extraction from
six A-aquifer wells and one B-l zone well. The A-l zone Well 14,
which was initially used as an extraction well, was shut down on
November 10, 1988 because of repeated dewatering due to its
proximity to A-2 zone extraction Well 15. The average total
extraction rates in 1987, 1988 and 1989 were 11.3, 16.5 and 19.1
gallons per minute (gpm).
Extracted groundwater is currently treated by air stripping and
discharged to the storm drain system via NPDES permit. The
original groundwater treatment system included an air stripping
unit and a bio-oxidation unit in series. Based on the air
stripping unit effluent quality and the economic inefficiency of
the bio-oxidation unit, VW&R requested and received approval from
8
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the RWQCB to eliminate the bio-oxidation unit from the qrounCiwater
treatment system. VW&R removed the bio-oxidation unit from service
in early July 1990.
The capture zone created by the existing extraction wells appears
to be effectively containing the growldwater contamination plume
below the VW&R site.
4.1.2
SBLBCTBD RBHBDY
The selected groundwater remedy for VW&R consists of expanded
groundwater extraction and treatment by air stripping; monitoring;
and institutional controls. Additional A-aquifer extraction.wells
will be installed near the open dock and northern site boundary.
The total qroundwater pumping rate from the A-aquifer will be 40
gpm. Additional B-aquifer extraction wells will be installed near
the open dock and hydraulically downqradient of the rail spur. The
total qro.undwater pumping rate from the B-aquifer will be 100 gpm.
Due to accessibility problems in the area of the underqround tanks,
soil will be remediated in two phases. Because of this, both
initial and final cleanup requirements have been established for
soils. Immediate requirements are for temporary capping of the
entire site (until the underqround. tanks can be excavated);
treatment of soil "hot spot" areas by in-situ soil vapor extraction
(ISVE); and institutional controls. . Final soil requirements
include continued ISVE; and investigation and cleanup as necessary
in and around the underground tank farm when these areas become
accessible. Treated qroundwater will continue to be discharged
under NPDES permit to the storm drain system. The air stripper and
ISVE treatment will include air emissions control if emissions
exceed levels permitted by the BAAQMD.
4.2
ROLB OP 'l'BB RBSPONSB ACTIO.
The selected remedy addresses the risks posed by contaminated
groundwater in the upper aquifer zone and the principal threats
posed by contaminated soils on site. The principal threats are:
further lateral migration of the qroundwater contamination plume
emanating from the VW&R site; potential vertical migration of
contaminated qroundwater into the lower aquifer zone; and migration
of contaminants from onsite soil into qroundwater.
The objective of the selected remedy is to remove and permanently
destroy the contaminants from both soils and qroundwater or to
significantly reduce the toxicity, mobility or volume of hazardous
substances in both media. The selected response actions will
greatly reduce the possibility of contamination of current and
potential water supplies.
9
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5.0
SUKNARY OP SITB CHARACTERISTICS
5.1
SOURCES OP CONTAMINATION
The potential sources investigated at the VW&R site include an
accidental release of PCE from an aboveground 12,000-gallon blend
tank in 1977 at the loading dock and leaks from underground storage
tanks and associated piping. 50il and groundwater investigations
indicated the distribution of PCE and other volatile organic
compounds (VOCs) located in the vicinity of the loading dock.
5.2
DESCRIPTION OP CONTAMINATION
5.2.1
SUBSURPACB STRUCTURES/SOIL IHVBSTlGATIONS
The highest VOC concentrations in soil are located along the
northern edge of the loading dock and near the rail spur. 50il VOC
contamination extends approximately 50 - 80 feet north.and east of
the loading dock. 50il in the area of the loading dock contains
VOCs in concentrations in excess of 100 ppm. Figures 4. an.d 5
illustrate the areas of total VOC concentrations in soil at 5-foot
and 10-foot depths, respectively. These chemical isoconcentration
contours are based on five sets of soil quality data collected over
a five-year period from October 1983 to November 1988.
The volume of soil containing greater than 1 ppm total VOCs is
approximately 46,000 cu. yds.i the volume of soil at greater than
100 ppm total VOCs is approximately 830 cu. yds. PCE is the most
widespread VOC in soil. The volume of soil containing greater than
1 ppm PCE is approximately 21,100 cu. yds.
Fourteen"of the 37 underground storage tanks have been emptied and
taken out of service based on the results of tank integrity tests;
however, the tanks remain in place. Areas located immediately
adjacent to and underneath the underground storage tanks are
currently inaccessible and have not been fully characterized. The
selected remedy includes removal of the underground storage tanks
by 1996. At that time, additional investigations will define the
extent of any contamination in the area.
5.2.2
GROURDWATER I:HVESTlGATIONS
Groundwater contamination at the VW&R site is limited to the upper
aquifer zone (the A-aquifer and the upper portion of the B-
aquifer). The groundwater contamination plume measures
approximately 500 feet by 500-800 feet laterally and extends to a
depth of 80 feet. As with soil contamination at the site,PCE is
the VOC detected most frequently and in the highest concentrations.
Figure 6 provides PCE isoconcentration contours in the A-aquifer.
The highest VOC concentrations are present in those wells in or
adjacent to the open dock and rail spur areas. Concentrations of
VOCs in the A-aquifer near the open dock have exceeded 10,000 ppb
for PCE. The maximum concentration of PCE has been 55,000 ppb in
the area of the loading dock.
10
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VW&R has completed 26 groundwater monitorinq and extraction wells
in the A-aquifer. The lateral extent of the groundwater
contamination plume is within VW&R's property boundaries except at
the western edqe, where the plume extends approximately 100 to 150
feet beneath the adjacent property. The western boundary of the
plume in the A-aquifer requires additional definition; extraction.
of groundwater at Well 28 in this area as part of the selected
remedy is expected to help to define this boundary. The plume has
also migrated sliqhtly beyond the northern _boundary of the site,
but at concentrations below cleanup standards.
There are 10 monitorinq and extraction wells in the B-1 zone and
three in the B-2 zone of the B-aquifer. The maximum concentration
of PCE detected in the upper portion of the B-aquifer is 1100 ppb,
aqain from a well in the area of the loadinq dock. The boundary of
the plume in the B-1 zone is relatively well defined except in the
area of the rail spur located near the open dock and
north/northwest of the underground storaqe tanks. Implementation
of the groundwater extraction system in the B-1 zone is expected to
help define the plume boundary in this area. The current plume
definition in both the A- and B-aquifers is sufficient to select a
final groundwater remedy. Additional monitorinq welles) may be
needed for lonq-term plume definition and monitorinq.
Table 1 lists averaqe and maximum concentrations for chemicals of
concern in soil and groundwater at the VW&R site.
'.0
SUMMARY OP SXTB aXSKS
'.1
TOXXCXTY ASSESSKEHT
The Baseline Public Health Evaluation (BPHE) conducted for the VW&R
site identified twenty compounds as the primary compounds of
interest. From these, the followinq eiqht chemicals of concern in
soil and groundwater at the site were identified:
acetone
1,1-dichloroethylene (l,l-DCE)
cis-1,2-dichloroethylene (cis-1,2-DCE)
methylene chloride
tetrachloroethylene (PCE)
1,1,1-trichloroethane (l,l,l-TCA)
trichloroethylene (TCE)
vinyl chloride
The followinq criteria were used to select chemicals of concern at
the VW&R site:
o
Frequency of detection. Typically, when at least twenty
samples are available, chemicals detected in less than five
percent of the samples are not considered to be of concern.
At the VW&R site, some chemicals were sampled infrequently
(e.q., less than 20 samples) and these chemicals were
included as chemicals of concern in the risk assessment.
11
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TABLE 1
- .
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CHEMICALS OF CONCERN AT VAN WATERS & ROGERS
Chemical Mean. Maximum
Concentration
80i1: (ppm) (ppm)
Acetone 11 500
1,1-Dichloroethylene 0.5 24
1,2-Dichloroethylene 0.6 7.5
(cis/trans)
Methylene chloride 5.4 210
Tetrachloroethylene 2.6 250
1,l,1-Trichloroethane 0.7 997
Trichloroethylene 0.9 37
Vinyl chloride 0.5 1
Frequency of
Detection
16/26
81/20.9
33/134
33/150
144/210
112/209
103/209
. 6/150
A-Aquifer Groundwater: (ppb) (ppb)
Acetone 1,900 74,000 12/103
1,1-Dichloroethylene 240 56,000 84/180
1,2-Dichloroethylene 680 38,.000 121/180
. (cis/trans)
Methylene chloride 36,000 670,000 28/180
Tetrachloroethylene 610 96,000 124/180
1, 1, 1-Trichloroethane 230 430,000 121/180
Trichloroethylene 170 40,000 100/180
Vinyl chloride 420 66,000 72/180
B-Aquifer Groundwater:
Acetone 18 34 2/95
1,1-Dichloroethylene 4.0 1,100 12/106
1,2-Dichloroethylene 9.1 170 9/106
(cis/trans)
Methylene chloride 8.9 14 4/106
Tetrachloroethylene 40 3,300 41/106
1, 1, 1-Trichloroethane 9.8 1,500 44/106
Trichloroethylene 8.9 1,600 31/106
Vinyl chloride 2.5 2.5. 1/106
.
Geometric mean of detects only
.
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o
Historical use. Chemicals that were used or stored
on site or were reported to have been spilled or leaked from
underground storage tanks may be selected as chemicals of
concern. Chemicals that have been stored on site and
detected in environmental media at the VW&R site include
acetone, ethylene glycol, methyl ethyl ketone, methyl
isobutyl ketone, methylene chloride, tetrachloroethylene,
toluene, 1,1,1-trichloroethane, and xylenes.
o
Toxicity. Chemicals for which available information
indicated low toxicity, and which are present in low
concentrations compared to the other chemicals present., were
not selected as chemicals of concern. Chemicals for which
EPA has not established toxicity criteria for human health
were also not considered as chemicals of concern. All Group
A and B carcinogens were included in BPHE calculations.
6.2
EXPOSURE ASSESSKBHT
The BPHE identified and evaluated exposure pathways for both the
current land use condition and for hypothetical future land use
conditions. Assessment of potential risk under the current land
use scenario was conducted to determine the degree that chemical
residues currently present in soil and groundwater at the site may
impact the health of humans who currently lj.ve or work at or in the
vicinity of the site. Assessment of potential risk under the
future land use scenario was conducted with the assumptions that
the site and vicinity would be converted to a typical residential
area and that the population will use the upper aquifer ground
water as a potable domestic water supply.
Through a process of identifying and evaluating all. of the
potential exposure pathways associated with the contamination, the
BPHE process identified complete exposure pathways at the site. A
complete exposure pathway has four components: a source and
mechanism of chemical release to the environment, an environmental
transport medium (e.g., air, soil), a potential human exposure
point, and a likely route of human exposure (e. g., inhalation). No
complete exposure pathways were identified for current use
condi tions. The two exposure pathways that were identified as
potentially complete for future land. use were ingestion and
inhalation of shallow groundwater from the A-aquifer and B-1 zone
underlying the site.
Under current land use conditions, the groundwater underlying the
site is not used for any purposes and has not impacted deeper
aquifer regions used for drinking water. Direct contact with
contaminated soil and wind erosion of soil contaminants are not
likely to occur since the site is paved. Release of soil
contaminants to ambient air by volatilization is also unlikely
under current conditions. Since the site is paved and underlain by
'clay, the upward migration of volatile contaminants is considered
unlikely.
Under future use conditions, the VW&R site could be developed as
commercial or residential property. If this were to occur without
12
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remediation of the site, on-site workers and residents could be
exposed to site contaminants. Conversion of the property to
residential uses is less likely than conversion to other industrial
or commercial uses, due to the industrial nature of the adjacent
properties. However, residential uses would lead to higher
potential exposures than would commercial uses, due to the
potential for greater frequency of exposure to contaminated media.
In addition, the residential population could also include more
sensitive individuals such as asthmatics, young children and the
elderly. For these reasons, residential use scenarios were
developed to provide a conservative indicator of potential future
risks from site contamination. .
An addi tional pathway of potential concern could resul t from
exposure to VOCs migrating to the surface from contaminated
groundwater. This exposure pathway is currently considered an
unlikely health risk. The risks from the emission of contaminants.
from the subsurface are currently difficult to quantify and a
formal risk assessment of this pathway for a worst case future
residence was not conducted. There are currently no.residences
above or in the immediate vicinity of the plume. As noted above,
it is unlikely that future residences will be built above the plume
since this area is not currently zoned for residential development.
Deed restrictions on the VW&R property as part of the selected
remedy will prevent residential development above the groundwater
contamination plume. This pathway will be evaluated at the time of
the five-year review (as discussed in section 10.0) using EPA-
approved methodology currently under development.
Under a future use risk scenario, two exposure pathways were
evaluated for groundwater: 1) inhalation exposure to compounds from
the A-aquifer and B-1 zone during showering or bathing, and 2)
ingestion of 2 liters of A-aquifer and B-1 zone groundwater every
day for 30 years. Dermal exposure to chemicals in household water
was considered to be minimal in comparison to inhalation and
ingestion, and was not evaluated as a significant route of
exposure~ The average exposure to each chemical contaminant was
based on the mean of all values reported above the detection limit
for samples collected from June 1986 to December 1988~
6.3
RISK CBARACTBRIZATIOB
Table 2 summarizes the potential human health risks at the VW&R
site (Upperbound Lifetime Excess Cancer Risk Numbers and non-
carcinogenic Hazard Indices associated with future exposures to
.chemicals in groundwater and soil).
To be protective of human health, concentrations of chemicals that
have been determined to cause or are suspected to potentially cause
cancer, based on animal studies, must be reduced. The
concentrations must be at a level such that ingestion of 2 liters
of water containing the chemicals, everyday for 30 years, can
theoretically be expected to produce no more than one excess cancer
incidence per ten thousand adults (a risk of 1 x 10.4) to one excess
cancer incidence per one million adults (a risk of 1 x 10-6). This
Carcinogenic Risk Range is considered an appropriate risk range for
13
"
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---- -. -_.- -..
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--
TABLE 2
SUMMARY OF SITE RISKS
Total Upperbound
Lifetime Excess
Cancer Risks
Average
Case
Plausible
Maximum Case
-- -...__._- . -
-.- --
-. -
Noncarcinogenic
Hazard Index
Average Plausible
Case Maximum Case
CUrrent Use Scenario:
No complete exposure. pathways
Future Use Scenario:
Groundwater Ingestion:
A-Aquifer 2 x 10-3 6 X 10-3
B-1 Zone 4 x 10-5 1 X 10-2
Inhalation of Groundwater Contaminants:
A-Aquifer 4 x 10-4 1 X 10-3
B-1 Zone 2 x 10-5 2 X 10-2
> 1 (10) .> 1 (10)
< 1
> 1 (20)
1
1
< 1
< 1
.
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cleanup actions. The sum of upperbound Lifetime Excess Cancer Risk
Numbers for all chemicals of concern must fall within this range.
For non-carcinogenic chemicals, hazard indices are .calculated by
dividing the amount of each chemical that a person might be exposed
to over time (the Chronic Daily Intake) by the level for each
chemical above which adverse health effects may occur (the
Reference Dose). The sum of these ratios for all the chemicals of
concern is the Hazard Index (HI). A HI of 1 or less means that no
adverse health effects should occur from drinking' water.
Under the future risk scenario, the total average case carcinogenic
risk from VOCs in A-Aq\!ifer groundwater at the VW&R site was
calculated at 2.4 X 10-3 and the total plausible maximum case
calculated at 7 x 10-3. The total non-carcinogenic Hazard Index
(HI) for VOCs from use of shallow groundwater was greater than 1
for either average or maximum case scenarios.
6.3
PRESENCB OF SENSITIVE BUMAH POPULATIONS
As noted earlier, the VW&R site is located in an exclusively
industrial/commercial zoned area. There are no residences
overlying the contaminant plume. There are also no public parks,
schools, hospitals, or convalescent homes within or near the plume
boundaries. The nearest residences are a mobile home park
approximately 1.5 miles to the northeast and a farm approximately
2500 feet to the north/northwest.
6.4
PRESENCB OF SENSITIVE ECOLOGICAL SYSTEMS
The VW&R site is located in an industrial area with little native
vegetation or wildlife. Nearby aquatic environments include the
Guadalupe River, which receives surface runoff from the 'site and
treated groundwater discharged under an NPDES permit into the storm
drain system tributary to the river. Surface runoff from chemical
storage/handling areas is prevented from entering the storm drain
inle~s near the concrete apron by concrete berms around the drain
inlets. Established limits under the NPDES permit are intended to
protect aquatic life. Thus, no adverse impacts are expected on
aquatic populations in the Guadalupe River. .
Coyote Creek is closer to the site than the Guadalupe River;
however, based on topography and the configuration of the storm
drain system, Coyote Creek is not affected by activities at the
site. Both the Guadalupe River and Coyote Creek discharge into San
Francisco Bay, approximately nine miles away from the site.
For terrestrial animals or birds, potential impact from exposure to
surface water is not expected to be significant due to the nature
of the chemicals and those of the species. Bioaccumulation in the
food chain is not likely to be significant. The VW&R site and
immediate vicinity does not constitute critical habitat for
. endangered species nor does it include or impact any wetlands.
14
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6.5 . COBCLUSIOR
Actual or threatened releases of hazardous substances from the VW&R
site, if not addressed by implementing the response action selected
in this ROD, may present an imminent and substantial endangerment
to the public health, welfare or environment. Based on the fact
that a variety of the VOCs detected at the site pose significant
health risks as carcinogens or noncarcinogens and that complete
exposure pathways exist, EPA has determined that remediation is
warranted.
7.0
APPLICABLB OR RELBVUT AIm APPROPRIATB REQUIRBKBBTS (:&RARS)
Under section 12i(d) (1) of CERCLA, S 9621, remedial actions must
attain a degree of clean-up which assures protection of human
health and. the environment. Additionally, remedial actions that
leave any hazardous substance, pollutant, or contaminant on-site
must meet a level or standard of control that at least attains
standards, requirements, limitations, or criteria that .are
"applicable or relevant and appropriate" under the circumstances of
the release. These requirements, known as "ARARs", may be waived
in certain instances, as stated in section 121(d) (4) ofCERCLA, 42
U.S.C. S 9621(d) (4).
"Applicable" requirements are those clean-up standards, standards
of control and other substantive environmental protection
requirements, criteria, or limitations promulgated under federal or
state law that specifically address a hazardous substance,
pollutant or contaminant, remedial action, location, or other
circumstance at a CERCLA site. "Relevant and appropriate" re-
quirements are clean-up standards, standards of control and other
substantive environmental protection requirements, criteria, or
limitations promulgated under federal or state law that, while not
"applicable" to a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstance at a CERCLA site,
address problems or situations sUfficiently similar to those
encountered at the CERCLA site that their use is well- suited to
the particular site. For example, requirements may be relevant and
appropriate if they would be "applicable" but for jurisdictional
restrictions associated with the requirement. See the National
Contingency Plan, 40 C.F.R. Section 300.6, 1986).
The determination of which requirements are "relevant and ap-
propriate" is somewhat flexible. EPA and the State may look to the
type of remedial actions contemplated, the hazardous substances
present, the waste characteristics, the physical characteristics of
the site, and other appropriate factors. It is possible for only
part of a requirement to be considered relevant and appropriate.
Additionally, only substantive requirements need be followed. If
no ARAR covers a particular si tuation, or if an ARAR is not
sufficient to protect human health or the environment, then non-
promulgated standards, criteria, guidance, and advisories must be
used to provide a protective remedy.
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7.1
TYPBS OF AltARS
There are three types of ARARs. The first type includes
"contaminant specific" requirements. These ARARs set limits on
concentrations of specific hazardous substance, pollutants, and
contaminants in the environment. Examples of this type of ARAR are
ambient water quality criteria and drinking water standards. The
second type of ARAR includes location-specific requirements that
set restrictions on certain types of activities based on site
characteristics. These include restriction on activities in
wetlands, floodplains, and historic sites. The third type of ARAR
includes action-specific requirements. These are technology- based
restrictions which are triggered by the type of action under
consideration. Examples of action-specific ARARs are Resource
Conservation and Recovery Act ("RCRA"). regulations for waste
treatment, storage, and disposal.
ARARs must be identified on a site-specific basis from information
about specific chemicals at the site, specific features of the site
location, and actions that are being considered as remedies.
7.2
CHEMICAL-SPECIFIC ARARS AND TBCS
Section 1412 of the Safe Drinkino Water Act. 42 U.S.C. Section
300 (0) (1)
Under the authority of Section 1412 of the Safe Drinking Water Act,
Maximum contaminant Level Goals (MCLGs) that are set at levels
above zero, shall be attained by remedial actions for ground or
surface water that are current or potential sources of drinking
water, where the MCLGs are relevant and appropriate under the
circumstances of the release based on the factors in
5300.400(g) (2).
The appropriate rem'edial cleanup standard for each chemical of
concern (except acetone) in groundwater is the MCLG (if not equal
to zero), the federal MCL, or the state MCL, whichever is most
stringent. As there is no chemical-specific ARAR or TBC for
acetone, a cleanup standard was calculated using a risk-based
approach.
California DeDartment of Health Services Drinkino Water Action
Levels (DWALs)
California Department of Health Services (DHS) DWALs are health-
based concentratiQn limits set by the DHS to limit pUblic exposure
to substances not yet regulated by promulgated standards. They are
advisory standards that apply at the tap for public water supplies.
These DWALs are not ARARs, but are liTo Be Considereds," or TBCs.
ARARs with more stringent requirements take precedence over these
DWALs.
Table 3 lists the chemicals of concern at the VW&R site and their
cleanup standards.
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California's Resolution 68-16
California's "statement of POlicy With Respect to Maintaining High
Quality of Waters in California," Resolution 68-16, affects
remedial standards. The policy requires maintenance of. existing
water quality unless it is demonstrated that a change will benefit
the people of the state, will not unreasonably affect present or
potential uses, and will not result in water quality less than that
prescribed by other state pOlicies.
7.3
ACTION SPBCIPIC ARARS AND TBCS
National Pollutant Discharae Elimination Svstem (NPDES)
NPDES substantive permit requirements and/or RWQCB Waste Discharge
Requirements (WORs) are potential ARARs for effluent discharges. .
The effluent limitations and monitoring requirements of an NPDES
permit or WORs legally apply to point source discharges such as
those from a treatment system with an outfall to surface water or
storm drains. The RWQCB established effluent discharge limitations
and permit requirements based on Water Quality standards set forth
in the San Francisco Bay Regional Basin Plan. .
EPA Office of Solid Waste and Emeraencv ResDonse (OSWER) Directive
9355.0-28
OSWER Directive 9355.0-28, "Control of Air Emissions from Superfund
Groundwater Air strippers at Superfund Groundwater Sites," applies
to future remedial decisions at Superfund sites in ozone non-
attainment areas. Future remedial decisions include Records of
Decision (RODs), Significant Differences to a ROD and Consent
Decrees. The VW&R site is in an ozone non-attainment area. OSWER
Directive 9355.0-28 requires such sites to control total volatile
organic compound emissions from air strippers and soil vapor
extractors to fifteen pounds per day per facility. This directive
is not an ARAR, but is a TBC. ARARs with more stringent
requirements take precedence over the directive.
Bav Area Air Oualitv Manaaement District (BAAOMD) Reaulation 8.
Rule 47
The BAAQMD Board of Directors adopted Regulation 8, Rule 47, "Air
Stripping and Soil Vapor Extraction Operations." This rule applies
to new and modified operations. The rule consists of two
standards: -
o
Individual air stripping and soil vapor extraction
operations emitting benzene, vinyl chloride, perchloro-
ethylene, methylene chloride and/or trichloroethylene are
required to control emissions by at least ninety percent
by weight. Operations emitting less than one pound per
day of these compounds are exempt from this requirement
if they pass a District risk screen.
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o
Individual air stripping and soil vapor extraction
operations emitting greater than fifteen pounds per day
of organic compounds other than those listed above are
required to control emissions by at least ninety percent
by weight.
Regulation 8, Rule 47 is an ARAR for the implementation of the
remedy at the VW&R site.
Resource Conservation
Restrictions
and Recoverv Act
(RCRA\
Land
DisDosal
The contaminated groundwater contains spent solvents that are RCRA
listed wastes. TCE is an FOOl listed waste, and TCA is an F002
listed waste. Adsorbents and other materials used for remediation
of groundwater VOCs, such as activated carbon, chemical-absorbing
resins or other materials used in -the treatment of groundwater or
air, will I;:ontain the chemicals after use. RCRA land disposal'
restrictions are not applicable but are relevant and appropriate to
disposal of treatment media due to the presence of constituents
which are sufficiently similar to RCRA wastes.
In addition, RCRA Land Disposal Restrictions may be 'an ARAR for
those alternatives involving excavation of contaminated soil for
on-site treatment.
BAAOMD Reaulation 8. Rule 40 (Februarv 15. 1989\
This regulation is an ARAR applying to the aeration of VOC-
containing soil resulting from the excavation of underground
storage tanks. This rule allows uncontrolled releases if the
organic content of the soil is less than 50 mg/kg; otherwise,
control of 90 percent of the emissions is required.
7.4
LOCATION-SPECIFIC ARARs
Fish and Wildlife Coordination Act
The Fish and Wildlife Coordination Act is an applicable requirement
for the locations adjacent to the Guadalupe River and other
tributary streams and marshes.
8.0
DESCRIPTION OP ALTBRH1TIVBS
8.1
REMEDIAL ACTION OBJECTrvES
Cleanup of groundwater contamination at the VW&R site focuses on
the fOllowing remedial action objectives:
~) Prevention of current or future exposure of human receptors to
contaminated groundwater or soil
2) Restoration of the contaminated groundwater for potential
future use as a drinking water source
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3)
4)
Control of contaminant migration
Monitoring of contaminant concentrations in the groundwater.
8.2
CLBAHUP STANDARDS
~: No ARARs exist for soil. Due to accessibility problems in
and around the underground storage tank area and beneath existing
structures, soil cleanup levels are separated into interim and
final standards for the VW&R site. As an interim cleanup standard,
soil "hot spots" (defined as accessible areas in which the
concentrations of anyone of the chemicals PCE, TCA or TCE exceed
10 ppm) will be remediated to levels not to exceed 10 ppm, in order
to minimize the potential migration of soil contaminants to
groundwater. The final soil cleanup standard (after
characterization of the soil surrounding the tanks and associated
piping at the time the tanks are removed) will be continued
remediation of all contaminated soil until concentrations of 1 ppm
total VOCs are achieved.
Groundwater: Cleanup standards for all chemicals of concern
(except acetone) in the A- and B-aquifers are the ARARs identified
in Table 3. For acetone, a risk-based approach using exposure
assumptions was used to establish a cleanup standard that would be
protective of human health. Treatment of groundwater at the VW&R
site to these levels will result in an acceptable excess cancer
risk of 4 x 10-5 and a non-carcinogenic hazard index (HI) of less
than 1.
Table 4 lists the cleanup standards for the chemicals of concern
and the corresponding health risks of leaving these chemicals in
the groundwater at these levels. Concentrations of other chemicals
detected at the site will be reduced in the process of achieving
the cleanup standards for the eight chemicals of concern.
The point of compliance for groundwater remediation is throughout
the aquifer and includes all groundwater wells. Cleanup standards
for extracted groundwater that will be discharged to the storm
drain system are listed in the current NPDES permit for VW&R's
interim remedial actions. These standards apply at the point of
discharge and are protective of human health and the surface water
environment.
~: The BPHE did not identify chemicals of concern in the air,
with the exception of those chemicals emitted to the air during
current interim groundwater treatment. These emissions are
regulated under the current or future modified BAAQKD permit;
therefore, no additional remedial action objectives have been
generated for air emissions.
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TABLE 3
GROUNDWATER CLEANUP STANDARDS
FOR CHEMICALS OF CONCERN
(Concentrations in ppb)
Chemical Federal California Target Cleanup
MCL/MCLG MCL Level
Acetone 4200*
1,1-Dichloroethylene 7/7 6
cis-1,2-Dichloroethylene 70/70 6
Methylene chloride 5/0 **
Tetrachloroethylene 5/0 5
l,l,l-Trichloroethane 200/200 200
Trichloroethylene 5/0 5 ----
Vinyl chloride 2/0 0.5
*
Target cleanup level calculated using risk-based approach
**
Proposed
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TABLE 4
GROUNDWATER CLEANUP STANDARDS AND CORRESPONDING RISKS
Final Remediation Levels Corresponding Risk Levels
Chemical Remediation Basis Carcinogen Non-Carcinogen
Level (ppb)
Acetone 4200 Risk 0.840
.: 1, 1-DCE 6.. . .'CA. MCL . -5 0.013
2.8.x..10
cis-1,2-DCE 6 CA MCL 0.012
Methylene 1.9 x 10-6
.chloJ;'ide '. .:5 . MCL 0.002
PCE 5 MCL 7.0 X 10-7 0.010
1,1,1-TCA 200 MCL 0.018
TCE 5 MCL 3.1 x 10-7 0.014
Vinyl chloride 0.5 CA MCL 4.0 X 10-7
4.0 X 10-5 0.899
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8.3
RBKBDIAL ACTION ALTBRJlATIVE8
Al ternati ves addressing soil and groundwater contamination and
remedial action objectives were developed from a list of
technologies that remained after an initial screening of
technologies and general response actions.
Only two groundwater remedial technologies were retained for
further evaluation: 1) No Action for both the A- or B-aquifer and
2) extraction and treatment of A-aquifer groundwater by air
stripping and extraction and treatment of B-aquifer groundwater by
GAC or air stripping. Based on cost and concentration factors,
treatment of extracted groundwater by air stripping appears to be
the more appropriate process option for A-aquifer ground water,
whereas treatment by either GAC or air stripping is preferable for
groundwater extracted from the B-aquifer. For the purposes of
developing remedial alternatives for detailed evaluation, - air
stripping has been proposed for A-aquifer groundwater and GAC or
air stripping have been proposed for B-aquifer groundwater.
The approach to groundwater remediation in Alternatives 2, 3, 4 and
5 is similar. The remaining technologies evaluated - for soil
cleanup included capping, in-situ vapor extraction (ISVE), above-
ground aeration, and low-temperature thermal desorption.
Alternative 1 - No Action
The No Action alternative serves as a baseline for comparing other
remedial alternatives. Under the No Action alternative, no
additional remedial technologies would be implemented and
operations of presently implemented remedial actions would cease;
however, groundwater monitoring would continue.
Alternative 2 - CaDDina and Groundwater Treatment
Alternative 2 consists of capping of soils containing more than 1
ppm total VOCs; A-aquifer remediation by extraction and treatment
by air stripping; andB-aquifer remediation of groundwater by
extraction and treatment by Granular Activated Carbon (GAC) or air
stripping. Capping would be accomplished by paving the rail spur
area with an appropriate paving material and sealing the existing
asphalt and concrete-paved areas, where needed. The A-aquifer
extraction system would consist of the existing interim remedial
system and additional extraction wells installed in the vicinity of
_the open dock and along the northern site boundary. The total
extraction rate from the existing and new A-aquifer extraction
wells is expected to be approximately 40 gpm. The- existing
permitted air stripping unit would be utilized in the treatment of
extracted A-aquifer groundwater to the extent possible. To
accommodate the increased rate of extraction, an additional air
stripping unit would be installed. The current BAAQMD permit does
not require emissions control. The off-gas from the second air
stripping unit would be treated in accordance with BAAQMD
regulations.
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The B-aquifer extraction system would include wells near the open.
dock and hydraulically downqradient from the rail spur. This
configuration of extraction wells is expected to significantly
reduce miqration toward the northern site boundary and minimize
off-site miqration of organic chemicals at concentrations above the
target cleanup levels. Existing monitoring wells would be
converted to extraction wells wherever possible. The total rate of
extraction from the B-aquifer is expected t~ be approximately 100
qpm. B-aquifer qroundwater would be treated by either GAC (since
the average VOC concentrations are expected to be relatively low)
or air stripping.
Treated qroundwater will be discharged to the Guadalupe River, via
the storm sewer system, under a modified NPDES permit issued by the
RWQCB. '.
Alternative 3 - ISVE Treatment of Soil "Hot SDOtS" and Groundwater
Treatment .
Under Al ternati ve 3, groundwater would be extracted from the A- and
B-aquifers and treated as outlined under Alternative 2. CUrrently
accessible areas of soil containing more than 10 ppm of one or more
of the chemicals PCE, TCA and TCE (areas termed "hot spots ") would
be treated using ISVE. This would involve approximately 8100 cu.
yds. of soil. The estimated time to reach groundwater cleanup
standards is 13 years; the estimated time to reach final cleanup
standards for soil using ISVE is approximately 3 years.
Al ternati ve 4 - CaDDina. ISVE of "Hot SDotS." and Groundwater
Treatment
This alternative represents a combination of Alternatives 2 and 3.
Soil containing qreater than 1 ppm total VOCs would be capped and
accessible "hot spots" as described in Alternative 3 would be
treated using ISVE. A- and B-aquifer qroundwater would be
extracted and treated as in Alternative 2.
Alternative 5 - CleanuD to Backaround Levels for Groundwater and
1 DDm Total VOCs for Soil
This alternative involves immediate remediation of all vadose zone
soil containing more than 1 ppm total VOCs; and groundwater
remediation to backqround levels, in both the A and B aquifer, by
extraction and treatment. The approach to groundwater remediation
is similar t~ that in Alternatives 2, 3 and 4; however, remediation
would continue for an estimated 63 years, until background
groundwater quality conditions were achieved. Three different
approaches to soil remediation have been evaluated:
5-b)
Excavation of onsite soils containing qreater than
1 ppm total VOCs with treatment by aboveqround aeration;
Excavation of onsite soils containing greater than
1 ppm total VOCs with treatment by low temperature
thermal desorption;
5-a)
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ISVE in areas where total VOC concentrations exceed 1
ppm. Over 200 ISVE wells would be needed for this
option.
The areas at which soil contains more than 1 ppm total VOCs include
the covered dock, open dock, concrete apron, and significant
portions of the adjacent areas. An estimated 46,000 cu. yds. of
soil would be remediated. Excavation would necessitate the
demoli tion of the open and covered docks ~ It is assumed for
purposes of comparison with other alternatives that an excavation
of this magnitude could only be performed subsequent to closure of
the facility. Soil remediation by ISVE in Alternative 5c would
involve installing over 200 vapor extraction wells on 20-foot
centers throughout an area of 75,200 square feet centered around
the open dock.
5-c)
'.0
COMPARA'l'IVB ANALYSIS OF AL'l'BRRA'l'IVBS
This section provides an explanation of the criteria used to select
the remedy, and an analysis of the remedial action alternatives in .
light of those criteria, .highlighting the advantages and
disadvantages of each of the alternatives.. .
'.1
CRI'l'ERIA
The alternatives were evaluated using nine component criteria.
These criteria, which are listed below, are derived from require-
ments contained in the National Contingency Plan (NCP) and CERCLA
Sections 121(b) and 121(c).
1.
Overall protection of human health and the
environment
2. .
Short term effectiveness in protecting human
health and the environment
3.
Long-term effectiveness and permanence in
protecting human health and the environment
Compliance with ARARs (ARARs are detailed in
Section 7.0)
4.
5.
Use of treatment to achieve a reduction in the
toxicity, mobility or volume of the contaminants
6.
Implementabi1 ity
7.
State acceptance/Support Agency acceptance
Community acceptance
8.
9.
Cost
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9.2 ANALYSIS 01' ALTBRHATIVBS
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Except for Alternative 1, all of the remedial alternatives are
protective of human health and the "environment. Alternatives 2
through 5, if implemented, would each reduce potential excess
cancer risks associated with the ingestion or inhalation of organic
chemical-containing groundwater to less than 1 x 10-4. These
alternatives would also reduce potential noncarcinogenic adverse
health effects and result in a HI of less than 1. As groundwater
remediation to target cleanup levels (AI ternati ves 2, 3 and 4)
results in acceptable carcinogenic and non-carcinogenic health
risks, the additional effort and expense to remediate groundwater
to background levels (Alternative 5) is not warranted. The
hydraulic containment systems associated with Alternatives 2
through 5 prevent offsite migration of contaminated groundwater. "
wi th respect to soil, Al ternati ves 5-a and 5-b provide the greatest
overall degree of protection for human health and the environment.
These two alternatives would permanently remove and destroy the
majority of contaminants in soil. Alternatives 2, 3, 4 and 5-c
provide somewhat less protection by leaving detectable levels of
VOCs in soils. However, capping (AI ternati ves 2 and 4) would
prevent direct contact with contaminated soil at the si te and
prevent leaking to groundwater.
COMPLIANCE WITH ARARS
Alternative 1 would
alternatives would.
5-b or 5~c would be
68-16.
not meet all drinking water ARARSi all other
Site remediation by either Alternatives 5-a,
expected to comply with the state Resolution
NPDES permit requirements would be" met by proper design and
operation of either treatment system. The Fish and wildlife
Coordination Act would not be an ARAR for any alternatives because
the treatment system would ensure that discharged water was
protective of human health and the environment.
RCRA land disposal restrictions would apply to the spent carbon
from Alternatives 3 through 5. The spent carbon could be treated
before reuse or disposal by an incineration process. Alternatives
5-a and 5-b may not meet land disposal restrictions for the
excavated soil.
soil remediation by either of Alternative 5-a or 5-b may n9t comply
with potential action-specific BAAQMD ARARs for air due to the
large mass of organic chemicals that would be expected to
volatilize during excavation and/or aeration. Alternatives 3
through 5 would need to comply with OSWER Directive 9355.0-28 and
BAAQMD Regulation 8, Rule 47 because of the air stripper emissions.
These ARARs are addressed by the BAAQMD permitting process. If
permit modifications become necessary, emissions could be captured
and destroyed by available technology.
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REDUCTION OF TOXICITY. MOBILITY. OR VOLUME THROUGH TREATMENT
Alternative 1 allows conditions at the site to remain unmitigated.
There is no direct reduction in the toxicity, mobility or volume of
VOC-contaminated soil or groundwater. Alternative 5 would remove
and/ or destroy most of the contaminants present in soil, thus
reducing volume.
Alternatives 2, 3 and 4 would produce comparable reductions in the
toxicity and mObility of the contaminants but employ different soil
remediation technologies. Alternative 2 employs capping to reduce
the mobility of the organic chemicals in vadose zone soil either
upward to the atmosphere or downward to the water table.
Alternative 3 employs ISVE to remove the VOCs from soil. As soil
remediation by ISVE would result in lower residual VOC
concentrations, the reduction in toxicity and mobility would be
greater for Alternative 3 than for Alternative 2. Alternative 4
combines capping and ISVE in hot spots and so reduces toxicity and
mobility to levels lower than either of Alternatives 2 or 3. As
Alternative 2 is unlikely to achieve nondetectable concentrations
of VOCs, the volume of contaminated soil would be essentially
unchanged. Alternatives 3, 4 and 5 will reduce VOC concentrations
and thus the volume of contaminated soil.
LONG-TERM EFFECTIVENESS AND PERMANENCE
Alternative 1 is not effective in that the baseline excess risk
conditions that necessitate remediation remain unmitigated. If
implemented, Alternative 5 would be the most effective and
permanent of the alternatives. However, the complete remediation
afforded by Alternative 5 is not practical.
Alternatives 2, 3 and 4 offer a considerable reduction in excess
risk by capping and/or remediating contaminated soils. Although
contaminated soil would remain in place after implementation, the
combination of surface paving, hydraulic containment and
institutional controls is believed to provide adequate protection.
As the cleanup levels attainable by ISVE are likely to be lower
than the current soil conditions, the excess risk associated with
Alternatives 3 and 4 is likely to be somewhat lower than that for
Alternative 2.
In terms of the adequacy and reliability of controls, Alternatives
2 through 5 are comparable as each ~mploys similar institutional
controls and hydraulic containment systems. Each alternative
features some form of site security, surface paving to minimize
infiltration, and ,groundwater extraction/treatment. The degree of
reliability of these measures is similar for Alternatives 2 through
5.
SHORT-TERM EFFECTIVENESS
Alternative 1 does not involve disturbance of contaminated soil or
groundwater, and thus there are no risks to workers or the
community directly related to its implementation. The short-term
effectiveness of Alternatives 2, 3 and 4 is similar in terms of
24
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groundwater remediation, but Alternative 5 differs significantly
due to the time required (63 years) to achieve background levels.
Alternatives 2 through 5 also vary significantly in terms of soil
remediation and involve progressively higher levels of site
disturbance. Al ternati ves 2, 3 and 4 involve potential eXposure to
contaminated soil during paving, drilling for vapor or groundwater
extraction wells, and during . the handling and treatment of
contaminated groundwater. Some small releases of organic vapors to
the atmosphere would be expected during these activities; however,
the associated potential risk to the community and the environment
is expected to be negligible provided adequate safety precautions
are taken. The potential risk to workers involved in implementing
Alternatives 2, 3 and 4 is considered low and manageable. .
Alternative 5 could involve open excavation during which
significant quantities of organic vapors would be expected to
volatilize. In addition, Alternative 5. could include aeration as
the principal means of remediating soils. In terms of protection
of the community, protection of workers, and potential adverse
environmental impacts, Alternative 5 is considered least effective
in the short term.
In terms of the time required to achieve the remedial response
objectives for soil, Alternative 5-bwould require the least amount
of time. Soil remediation using Alternative 5-b could be completed
wi thin six months, despi te the large volume of soil to be
remediated. Soil remediation by ISVE (Alternatives 3, 4 and 5-c)
would require about three years. Excluding the No Action
alternative, and given that groundwater remediation under
Alternative 5 is least time effective, Alternative 2 is expected to
be the most effective, with Alternatives 3 and 4 being equally the
next most effective.
IMPLEMENTABILITY
In terms of construction and operation, the No Action alternative
is clearly the most easily implementable. Alternatives 2 through
5 are similar with respect to groundwater, but vary considerably in
terms of construction and operation of the soil remediation
technologies. Alternative 2 involves capping as well as upgrading
of currently paved surfaces and would be the simplest to construct
and maintain.
Alternative 3 features the next most implementable soil remediation
technology in that construction of the ISVE system is
straightforward. Operation of the ISVE system, particularly the
high vacuum extraction system and vapor treatment system, would be
relatively complex. System monitoring would. be required, with
periodic adjustments to flow rates and the operation of the vapor
treatment unit. Alternative 4, which involves adding .an engineered
cap to the soil remediation measures of Alternative 3, would be
similar to Alternative 3 in terms of implementability.
Alternative 5 is the most difficult to construct and operate in
terms of soil remediation and is not practical at an operating
facility. Alternative 5 involves extensive site modifications,
25
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i.e., demolition and tank removals or the installation of hundreds
of ISVE wells, prior to being implemented. ISVE on this scale is --
not considered practical at an operating facility due to the
complexity of the vapor transfer piping associated with the wells.
The initial setup and operation of the low temperature thermal
desorption unit would be highly specialized and time consuming.
In terms of permitting and the availability of services, the
requirements for Alternatives 2 through 5 vary but no critical
difficulties are anticipated. No permits or services are required
for Alternative 1. Alternatives 2 through 5 would involve air
quality permitting and NPDES permitting for the treatment and
discharge of groundwater. Permitting requirements for soil would
likely be least stringent for Alternative 2 and most stringent for
Alternative 5. Permitting for Alternative 5-a may be difficult
considering BAAQMD regulations. Permitting for Alternative 5-b may
also be difficult, as this alternative features the thermal.
destruction of organic chemical vapors by relatively complex
processes. Alternatives 3, 4 and 5-c will also require BAAQMD
permits. Field testing might also be required to demonstrate
compliance with the BAAQMD's requirement that emissions be reduced
by 90 percent by weight. .
The technologies and the associated services included in the
alternatives are available and field proven.
COST
Table 5 presents total overall costs (O&M plus Direct and Indirect
Capital Costs) for the five alternatives. The only costs
associated with Alternative 1 are expected to be related to
continued groundwater monitoring and decommissioning the interim
groundwater remediation system. Groundwater monitoring costs are
estimated at $148,000 per year based on the current scope of the
quarterly monitoring program. Assuming that monitoring continues
for 30 years, the. net .present value (NPV) of the estimated
monitoring costs is $2,275,000. (The NPVs for Alternative 1 and
the other al ternati ves are. based on a net interest rate of 5
percent. .
The principal costs for Alternative 2 would be for capping
currently unpaved areas, sealing existing paved surfaces,
installing groundwater extraction/treatment facilities, and long-
term monitoring. The principal costs for Alternative 3 would be
for the installation of the ISVE system, the procurement of the
ISVE system off-gas treatment facilities, groundwater extraction/
treatment facilities, and long-term monitoring. The principal
costs for Alternative 4 would be for capping currently unpaved
areas, sealing existing paved surfaces, installing the ISVE system,
the procurement of the ISVE system off-gas treatment facilities,
groundwater extraction/treatment facilities, and long-term
monitoring.
The principal costs associated with Alternatives 5a and 5b would be
demolition of the open and covered docks; underground storage tank
closure; excavation; soil treatment; backfilling and site
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TABLE 5
ESTIMATED COSTS FOR REMEDIAL ALTERNATIVES
(Costs in thousands)
Alternative 1 2 3 4 5-a S-b S-c
Direct
Capital Cost 22 173 389 409 3,416 9,259 1,205
Indirect 470- 450-
Capital Cost 12 114 206 214 528 507 505
NPV of O&M
for soil 132 400 438 1,312
NPV of O&M
for Groundwater' - 2,2752 3,936 3,936 3,9363 7,9903 7 , 9903 7,9903
Total 2,309 4,355 4,931 4,997 11,876- 17,699- 10,012
11,934 17,756
NPV = net present value
, based on 13 years of operation unless noted otherwise
2 based on 30 years of operation
3 based on 60 years of operation
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restoration; and qroundwater treatment. The principal costs
associated with Alternative Sc would be for procuring/installing
the large number of ISVE wells, the vapor transfer piping, and the
vapor treatment unit. The principal O&M costs would be those
associated with qroundwater treatment.
SUPPORT AGENCY ACCEPTANCE
The Feasibility study and the Proposed Plan Fact Sheet were
reviewed by California Regional Water Quality Control Board
(RWQCB). The RWQCB concurs with EPA's preferred alternative.
COMMUNITY ACCEPTANCE
The Proposed Plan was presented to the community of Mountain View
in a fact sheet and at a public meeting. No technical comments
were submitted regarding the al ternati ve$. Other comments received
are addressed in the Response Summary.
'.3
SELECTED RUEDY
'.3~1
DESCRIPTION OP REMEDY
The selected remedy is a modified version of Alternative 4. The
selected remedy provides for expanded qroundwater extraction and
treatment and a temporary soil cap. The selected remedy also
provides for interim remediation of soil "hot spot" areas and final
cleanup in and around the underground storage tank area when this
area becomes accessible after the tanks are removed in 1996.
'.3.1.1
SOILS
The selected soil remediation combines three technologies to
minimize the potential for organic compounds in soil to miqrate
into A-aquifer qroundwater. These technologies are capping, in-
situ soil vapor extraction (ISVE), and. hydraulic containment.
capping includes sealing the existing paved surfaces where
necessary and capping the rail spur ballast adjacent to the dock to
prevent surface water infiltration into the soil above the water
table. This will minimize the potential for leaching of organic
compounds into the qroundwater. ISVE will provide additional
protection against themiqration of chemicals into the qroundwater.
The hydraulic containment provided by the qroundwater extraction
system will be an additional safeguard against the potential for
organic chemicals in soil to migrate via groundwater.
Remedial actions for soils have been designed with corresponding
initial and final cleanup standards 'and include a final remedy
which provides coordination with current and future operations at
the site, and removes the long-term threat to water quality, as
follows:
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Initial Actions:
Temporary cap placement until removal of underground tanks
occurs. Evaluation of the effectiveness of the temporary cap
using the SESOIL model indicated that the thicknessof the cap
must be 31 em with a permeability of at least 1 x 10-7 em/sec.
o In-situ soil vapor extraction of accessible hot spot areas to
levels not to exceed 10 ppm of any of the chemicals PCE, TCE
or TCA.
o
Institutional controls consisting of site security, worker
protection and training and current land use zoning for
commercial/industrial.
Final Actions:
o
o
continued ISVE until l~vels of 1 ppm total VOCs is achieved,
unless no impact on water quality can be demonstrated at
higher concentrations.
o At the time of the removal of the underground tanks, and when
areas beneath existing structures become accessible,
additional soil and groundwater characterization and
reevaluation of alternatives to meet the 1 ppm cleanup
standard.
9.3.1.2
GROmmnTBR
A-aquifer groundwater remediation consists of extraction of
groundwater via a series of extraction wells, with treatment of the
groundwater by air stripping. The existing interim remediation
system would be supplemented by additional extraction wells
installed near the open dock and along the northern site boundary.
B-aquifer remediation consists of extraction from wells near the
dock- area. -The extracted groundwater will be treated using either
GAC or air stripping, as discussed previously. Remediation of B-
aquifer groundwater will focus on the source area behind the open
dock. Source area remediation is expected to achieve cleanup
levels throughout the B-aquifer.
Groundwater would be treated using the existing air stripper or a
new treatment system would be installed if groundwater extraction
rates exceed the capacity of the current system. Air stripper off-
gas would be regulated under the existing or modified BAAQMD permit
and treated effluent would be discharged under a modified RWQCB-
issued NPDES permit. Extraction and treatment of A- and B-aquifer
groundwater will continue until drinking water quality is achieved.
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In addition, the final groundwater remedy includes:
o Long term monitoring will be required after cleanup levels are
achieved.
o A deed restriction prohibiting use of on-site groundwater for
drinking water until final cleanup standards are achieved.
9.3.2
BASIS OF SELECTION
The modified version of Alternative 4 was selected because it will:
minimize the migrati~n of VOCs from soil to prevent degradation of
groundwater; reduce toxicity, mobility and volume; be protective of
human health and the environment by achieving the cleanu~ levels
within the Carcinogenic Risk Range of 1 x 10-4 to 1 x 10. , and a
noncarcinogenic HI below 1; meet all identified ARARs; be cost-
effective; and utilize implementable treatment technologies. .
Continued operation of groundwater extraction, treatment and
discharge facilities at the site and ISVE in vadose zone soils,
combined with a cap, will decrease the volume of the chemicals of
concern in the groundwater and the toxici ty of the groundwater.
The groundwater extraction, treatment and discharge alternative has
already been implemented at the VW&R site as an interim remedial
measure. An in-situ vapor extraction system of approximately 10 to
20 wells can be implemented relatively easily. Costs associated
with groundwater extraction facilities have already been incurred
by VW&R in implementing the interim remedial measures.
Al ternati ves 2, 3 and 4 share a common approach to groundwater
remediation and differ only in the soil remediation technologies
selected to minimize groundwater contamination. All three are
protective, comply with ARARs, are effective, and are practical in
terms of cost-effectiveness and the impact on facility operations.
Alternative 1 is not appropriate since it does not meet ARARs, and
Alternative 5 is not appropriate since it is not practical at an
operating facility and is not cost-effective. Soil leaching model
results presented in the RIfFS demonstrate that Alternative 2 would
minimize potential leaching of VOCs from soil to groundwater, while
Alternative 3 would decrease VOC concentrations in soil "hot
spots." A greater degree of groundwater protection is provided by
combining the soil remediation approaches of Alternatives 2 and 3,
as in the modified Alternative 4.
The selected remedy does not create any unacceptable short-term
risks. Although the selected remedy leaves the underground storage
tanks in place until 1996, VW&R is currently under a monthly tank
integrity testing program monitored by the Santa Clara Valley Fire
Department. In addition, a continuous monitoring system will be
installed. Thus, any leaks that may occur before the underground
tanks are removed in 1996 will be detected. An additional
safeguard is provided by the monitoring wells downgradient from the
underground storage tank area.
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Air stripping and carbon adsorption are equally effective at
treating the qroundwater contaminants, and only differ regarding
treatment. residuals. Under the current BAAQMD permit, residual
contaminants from the existing air stripper are released directly
to the air. Residual contaminants adsorbed to the liquid-phase
qranular activated carbon would be destroyed during regeneration or
confined to a small concentrated volume in a proper landfill.
Deed restrictions will be in place to prevent the construction of
any residences over areas which are potential sources of
contaminants vOlatilizing from soil or qroundwater beneath the site
to the surface. At the time of the required five-year review, the
need for continued deed restrictions for the site will be
determined using the approved EPA methodology for assessing risk
from indoor or outdoor exposure to residents on and near the site.
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10.0 STATUTORY DETERMINATIONS
The selected remedies are protective of human health and the en-
vironment, comply with federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and are cost-effective. This remedies utilize permanent
solutions and alternative treatment (or resource recovery) tech-
nologies to the maximum extent practicable and satisfy the
statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element.
Because the remedies will result in hazardous substances remaining
on-site above health-based levels, a five-year review, pursuant to
CERCLA Section 121, 42 U.S.C. Section 9621, will be conducted at
least once every five years after initiation of the remedial action
to ensure that the remedy continues to provide adequate protection
of human health and the environment.
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