United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R09-91/066
August 1991
if—<—
Superfund
Record of Decision
Advanced Micro Devices
#915, CA
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50272.101
REPORT DOCUMENTATION 11. REPORTNO.
PAGE. I EPA/ROD/R09-91/066
I~
3. Reclpienfo Accession No.
4. lll1e and Subtitle
SUPERFUND RECORD OF DECISION
Advanced Micro Devices #915, CA
First Remedial Action - Final
7. AuthO'(I)
5. Report Dete
0~/2 6/ 91
6.
8. I'vrfonnlng Orgonlzallon Rep~ No.
8. I'IIrfonnlng Orgolnlzatlon Name and Add....
10. ProjectlTaoklWork Unit No.
11. Contract(C) or Gront(G) No.
(C)
(G)
1~ Sponsoring OrglnIZ8tJon Name and Addre..
U.S. Environmental Protection
401 M Street, S~W.
Washington, D.C. 20460
13. Type of Report & Period Covered
Agency
800/000
14.
15. Supplementary Nolel
16. Abstract (Umlt: 200 WOrdl)
The Advanced Micro Devices (AMD) #915 site is an active semiconductor manufacturing
facility in Santa Clara County, California. The site consists of approximately 5 acres
and contains three physical structures, the largest of which is a 116,000-square-feet
building known as AMD 915. The site is in the Santa Clara Valley, and the facility
lies within an industrial park bordered by residential areas. Ground water from this
basin provides up to 50 percent of the municipal drinking water for 1.4 million
residents of the Santa Clara Valley. The site overlies three aquifers, one of which is
known as the B aquifer, which is approximately 20 to 100 feet below the surface. AMD
915 was built in 1974, and onsite manufacturing processes have involved the use of
solvents, caustics, and acids. Eleven chemical storage or treatment areas have been
documented at the AMD 915 facility including three underground acid neutralization
systems, two above-ground drum storage areas, and. six underground tank complexes. Two
of the acid neutralization systems remain in operation, as well as one drum storage
area, and two tank complexes. Records indicate that solvent wastes and other materials
were stored in underground tanks, and as many as 28 separate underground tanks may have
been in service at various times. In 1981, site investigations discovered soil
(See Attached Page)
17. Document AnalyoJa L Deocrlpto,.
Record of Decision - Advanced Micro Devices #915, CA
First Remedial Action - Final
Contaminated Medium: gw
Key Contaminants:- VOCs (benzene, TCE, toluene, xylenes), other organics, metals
(arsenic, chromium)
b. IdentifieroiOpan-Ended Tenna
c. COSA 11 ReIdlG,oup
18. AvailablUty Sta1emem
18. SecurIty Ct... (This Report)
None
211. SecurIty Ctaaa (ThI1 Poge)
None
21. No. 01 Pegel
58
n PrIce
See ANSI-Z38.18
See In8/nJctJOM on RiI-
1272 (4-11)
(Formeriy NTlS-35)
Deportment of Commerce
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::;:,
EPA/ROD/R09-91/066
Advanced Micro Devices #915, CA
First Remedial Action - Final
Abstract (Continued)
contamination during a planned underground storage tank removal. Two leaking
underground tanks were identified, and 7,000 cubic yards of contaminated soil were
removed. The majority of these tanks now have been removed from service or replaced.
In 1982, ground water 'contamination also was addressed and found to be limited to the
B aquifer. Additional offsite sources of ground water contamination may have a
significant effect on the AMD 915 site including commingling of ground water -
contamination. The most notable of these are Advanced Micro Devices 901/902
facilities, Signetics, and FEI Microwave. Two interim remedial actions for soil were
completed during 1981 and 1982, including offsite removal and disposal of a waste
solvent tank, and the removal of one acid neutralization system and 5,500 cubic yards
of soil. ,In 1982, ground water pumping and treatment using air stripping and carbon
~dsorption began onsite using existing building dewatering sumps. This was
supplemented with the installation of a series of wells during 1982 and 1988. This
Record of Decision (ROD) addresses remediation of onsite contaminated ground water.
The primary contaminants of concern affecting the ground water are VOCs including
benzene, TCE, toluene, and xylenes; other organics; and metals including arsenic and.
chromium.
The selected remedial action for this site includes continuing the operation of eight
existing ground water extraction wells; and treating contaminated ground water onsite
using air stripping and carbon adsorption, followed by discharge of the treated water
onsite to surface water. The estimated present worth cost for this remedial action is
$2,100,000. This figure represents the O&M costs for 30 years since the system is
already in place as an interim measure and no additional capital costs are required.
PERFORMANCE STANDARDS OR GOALS: Ground water clean-up standards are based on the more
stringent of Federal or State MCLs for drinking water. Chemical-specific goals for
ground water include PCE 5 ug/l (MCL), and TCE 5 ug/1 (MCL).
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RECORD OP DECISION
ADVANCED MICRO DEVICES #915
SUPERPtJND SITE
SUNNYVALE, CALIPORNIA
AUGUST 26, 1991
u.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 9
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RECORD OF DECISION
PART I:
DECLARATION
PART II: DECISION SUMMARY
PART III: RESPONSIVENESS SUMMARY
ADVANCED MICRO DEVICES #915
SUPERFUND SITE
SUNNYVALE, CALIFORNIA
AUGUST 26, 1991
u.s. ENVIRONMENTAL PROTECTION AGENCY
REGION 9
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",
" TABLE OF CONTENTS
PART I. DECLARATION '. '. ... . ';. . " ..,: .. .~'.. . .. . ... . . . . . . . .. .. . .
1.0 SITE NAME AND LOCATION.. .. . . . . . . ',' . . ','" . . . . .:. . . . . .
2.0 STATEMENT OF BASIS AND PURPOSE. . .,. .. '. : .. . . .. . . . . . . .
" 3.0 ASSESSMENT, OF THE SITE. . . . . . . . . . . . . . . .'. . . . . '. . . . . ',' .
,4.0 DESCRIPTION OF THE REMEDY. . .. . . . . . . . ,~ . . . . . . . ',' . . ; .. ,
5.0 DECLARATION . . . . . . . . . . . . . . . . . . . . . . . ; . . . . '. . . . . . . . . .
. . . ~
1
1
1
1
1
2'
, ,
PARTU.DECISIONSUMMARY.. ',"';' ',"'" .,................. ',' 3
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. . . . . . .. . . ; . . . . . . . . . . . . .. 6
1.5 HYDROGEOLo"GY.~' .... . . . . . . .. . .:. . . . . . .. . . . . . . .. 6
l.6 'WATER, USE. . . ',' . . . . . . . . ... . .. . : . '. . " . . . . . . . . . .. , 8
, 1.7' SURFACE AND SUBSURFACE'STRUCTURES ........... 10
2.0 SITE HISTORY AND ENF.ORCEMENT ACTIVITIES. . . . . . . . . . . ... ,12
, 2.1, HISTORY qF SITE ACTIVITIES. .. . . . .. .. . . . . . . . . . .. 12
2.2 ,'HISTORY OF SITE 'INVESTIGATIONS.. " . . . . .. . . . . . . : .. 13
2.3 ' HISTORY OF ENFORCEMENT ACTIONS; . . . . . . . . . . . . .. 15
3.0 COMMUNITY RELATIONS ',' . . . .. . . . . . . . . .. . . . . . . . . . . . . " 15
3.1 COMMUNITY INVOLVEMENT'.""""""""", .... 15
3.2 FACTSHE,ETS :.:.......,...................... 16
4.0 SCOPE AND ROLE OF THE RESPONSE ACTION. . . . . . . . " " . . . " " 16
, 4.1 ~ SCOPE OF THE RESPONSE ACTION. . . ; . . . . . ~ . . .. ... '16
4.1.1 Current Interim Remedial Measure (lRM) """','" 1 6
4.1.2 Selected Remedy. . . . . . .'.. . . .. . . . ~ '. . . . . . . .. 17
'4.2 ROLE OF THE RESPONSE ACTION. . . . . : . . . . . . . . . . . .' 17
5.0 SUMMARY OF $ITE CHARACTERISTICS '. . .. . .'" . . '. . . . . . . . . . .. 20
5.1 SOURCES OF CONTAMINATION. . . . . . . . . .. . . . . . . . . .. 20
5.1,.1 Sourc~ Investigation. . . . . . . . . . . . .. . . . .'. .. . .. 20
5.2 DE~CRIPTION OF CONT AMINA TION, . . . . . . . . . . . . . . . . .2'2
5.2.1 Soil Investigations . . . .,'.>. .: . .. .. .. . . . . . . . . ,. . '22
, 5.2.2' Groundwater Investigations. . . . . . . . .,.'.. . ',' . .. 22
, , ,- 5.2.3 Air Inv~stigations ... .'. . ',' .. . . . . . . .. .. ;'. .... 23
, 6.0 SUMMARY OF SITE RISISS .....;....................... 24
, 6.1 'TO,XICITY ASSESS'MENT .. . . .' .. .., . . . .. . . . . . . . . . . . . ,24
'6.2 RISKCHARACTERIZATION..'................ ... .. .' '27
6.2.1 -Soil...... ~ . . . . . . . '. . . . . . .'. . . . . . . " . : . . . ~ 2'7
6.2.3 Air... ", . . -. ',' . . . . . . . . . . . . ,. . . . . . . . . . . . . . . . ,28
, 6.3.3 'Grou'ndwater . . . . . . .,. . . . . . . . . . . . . .' . . . . . . .. 29
6.3 " PRESENCE OF SENSITIVE HUMAN POPULATIONS. . . . . ;. 31
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6.4 PRESENCE OF SENSITIVE ECOLOGICAL SYSTEMS. . . . . .. 31
6.5 CONCLUSION.................................. 31
7.0 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
(ARARS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31
7.1 TYPES OF ARARS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
7 .2 CONTAMINANT-SPECIFIC ARARS AND TBCS . . . . . . . . . .. 33
7.3 ACTION SPECIFIC ARARS AND TBCS ................ 34
7 .4 LOCATION-SPECIFIC ARARS ...................... 35
8.0 DESCRIPTION OF ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . .. 35
8.1 REMEDIAL ACTION OBJECTIVES. . . . . . . . . . . . . . . . . .. 35
8.2 GROUNDWATER CLEANUP STANDARDS. . . . . . . . . . . . .. 35
8.3 REMEDIAL ACTION ALTERNATIVES. . . . . . . . . . . . . . . .. 37
9.0 COMPARATIVE ANALYSIS OF ALTERNATIVES. . . . . . . . . . . . . .. 41
9.1 CRITERIA.................................... 41
9.2 ANALYSIS OF ALTERNATIVES. . . . . . . . . . . . . . . . . . . .. 43
9.3 THE SELECTED REMEDY. . . . . . . . . . . . . . . . . . . . . . . .. 48
9.3.1 Basis of Selection. . . . . . . . . . . . . . . . . . . . . . . .. 48
9.3.2 Features of the Remedy. . . . . .. . . . . . . . . . . . . .. 49
9.3.3 Uncertainty in the Remedy. . .. . . . . . . . . . . . . . .. 49
10.0 STATUTORY DETERMINATIONS. . . . . . . . . . . . . . . . . . . . . . .. 50
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES. . . . . . . . . . . . .. 51
PART III. RESPONSIVENESS SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . .. 51
1.0 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51
2.0 REGIONAL WATER QUALITY CONTROL BOARD RESPONSES. . . . .. 52
LIST OF FIGURES
Figure 1 - Regional Location of AMD 915 Facility. . . . . . . . . . . . . . . . . . . . .. 4
Figure 2 - General Location Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
Figure 3 - Schematic Geologic Log. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
Fi'lure 4 - Historical Waste Storage Locations. . . . . . . . . . . . . . . . . . . . . . .. 11
Figure 5 - Total VOCs In Groundwater. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
Figure 6 - AMD 915 Groundwater Extraction System. . . . . . . . . . . . . . . . . .. 19
LIST OF TABLES
TABLE 1 - NPDES DISCHARGE LIMITS, AMD 915 ..................... 21
TABLE 2 - AMD 915 DATA SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . .. 26
TABLE 3 - ADULT CARCINOGENIC RISK, AMD 915 . . . . . . . . . . . . . . . . . . .. 30
TABLE 4 - HAZARD INDEX AT CLEANUP STANDARDS. . . . . . . . . . . . . . . .. 38
TABLE 5 - CANCER RISK AT CLEANUP STANDARDS. . . . . . . . . . . . . . . . . .. 39
TABLE 6 - HEALTH INDICES AND CANCER RISK FOR CLEANUP STANDARDS OR
CURRENT MAXIMUM CONCENTRATIONS. . . . . . . . . . . . . . . . . . . . .. 42
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APPENDICES
APPENDIX A - RESPONSIVENESS SUMMARY
APPENDIX B - INDEX TO THE ADMINISTRATIVE RECORD
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PART I. DECLARATION
1.0 SITE NAME AND LOCATION
Advanced Micro Devices #91 5
915 DeGuigne Drive
Sunnyvale, CA 94088
2.0 STATEMENT OF BASIS AND PURPOSE
This Record of Decision ("ROD") presents the selected remedial actions for the
Advanced Micro Devices Building 915 (AMD 915) Superfund site in Sunnyvale,
California. This document was developed in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) as
amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA),
42 U.S.C. Section 9601 et. sea.. and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan, 40 C.F.R. Section 300 et. sea..
("NCP"). The attached administrative record. index (Appendix B) 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 action selected in this ROD, may present an imminent
and substantial endangerment to public health, welfare, or the environment.
4.0 DESCRIPTION OF THE REMEDY
The selected remedy for AMD 915 consists of groundwater extraction, treatment of
contaminated water with the existing air stripper, reuse of the treated water, and
discharge of a portion of the treated water to a storm drain tributary to surface water
under an NPDES permit. The air stripper will include air emissions control in the event
that emissions exceed levels permitted by the Bay Area Air Management District
(BAAQMD). Contaminated soils and structures were removed as part of interim
remedial actions and no further removals are necessary.
These remedial actions address the principal risk remaining at the AMD 915 site by
removing the contaminants from ground water, thereby significantly reducing the
toxicity, mobility or volume of hazardous substances. These response actions will
greatly reduce the possibility of contamination of existing potable water supplies and
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. potential future water supplies.
5.0 DECLARATION
The selected remedy is protective of human health and the environment, 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) technologies 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 ~ W "'"'-
Deputy Regional Administrator
B.2t,. 4/
Date
Page 2 of 52
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PART II. DECISION SUMMARY
This Decision Summary provides an overview of the problems posed by the Advanced
Micro Devices Superfund building 915 site (AMD 915) the remedial alternatives, and
the analysis of the remedial alternatives. This Decision Summary explains the
rationale for the remedy selection and how the selected remedy satisfies the statutory
requirements. .
1.0 SITE NAME, LOCATION, AND DESCRIPTION
1.1
SITE NAME AND LOCATION
Advanced Micro Devices (AMD) owns and operates a semiconductor manufacturing
facility at 915 DeGuigne Drive, Sunnyvale, Santa Clara County (AMD 915). The AMD
915 site is in a broad area bounded by the Bayshore Freeway, Central, and Lawrence
Expressways and Fair Oaks Drive (Figure 1). This is approximately four miles south
of the southern end of San Francisco Bay. The site has been treated as a single
operable unit based on groundwater data indicating that groundwater contamination
has been contained within the site boundary (Figure 2). Only AMD property has been
impacted by the releases of hazardous substances at the AMD 915 site.
1.2
REGIONAL TOPOGRAPHY
The Study Area is located in the Santa Clara Valley which is a gently-sloping alluvial
plain, flanked by the Diablo Range to the east-southeast and the Santa. Cruz
Mountains to the west- southwest. The Study Area is located toward the center of
the valley. The Santa Cruz Mountains are located several miles southwest of the
Study Area. The San Francisco Bay is located approximately 4 miles north of the
Study Area.
1.3
ADJACENT LAND USE
The AMD 915 site is in a broad area bounded by the Bayshore Freeway, Central and
Lawrence Expressways, and Fair Oaks Drive (Figure 1). The facility is located in an
industrial park setting bordered by residential areas (Figure 2). The area to the east is
predominantly commercial and retail space. The area immediately to the west is a
former High School, currently used as a research and development facility. Land to the
north of AMD 915 is a mix of multiple and single family residential property.
Page 3 of 52
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R E~IONALLOCATION
OF .AMD 915 FACILITY
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ADVANCED MICRO DEVICES
SUnn,..", C.llfoml8
GENERAl.. lOCATDI MAP
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-.----...--. .
FIGURE 2
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, 1.4.
. ,
. . ..
HISTORICAL LAND USE'
Until the Advanced Micro Devices 8uilding 915 was built in 1974 land use was
agricultural, dominantly. commercial fruit orchards. AMD 915was the first commercial
construction at this site., This facility was designed and has been used as a
semiconductor f~brication facility from 1974 through the present. The manufacturing
processes at this site have involved the use of solvents, caustics, and acids. No metal
plating has occurred at the AMD 915 facility.
1.5
HYDROGEOLOGY
Stratigraphy in the area surrounding the AMD 915 site is characterized byinterbedded
and interfingering sands, silts and clays. These sediments were deposited in complex
patterns by fluvial-alluvial systems draining the uplands to the south. Sediments were
deposited as the streams flowed north toward the 8ay.. '
The nomenclature applied to the water bearing units in the study area is representative
of the hydrogeology within the Santa Clara Groundwater 8asin. A number of shallow
water bearing units are separated from deeper aquifers by a thick persistent aquitard.
The .shallow units may be subdivided into a variety of zones depending upon depth,
lithology and lateral persistence. These zones are frequently labeled as A and 8 zones.
The deeper. aquifer is commonly referred to as the C aquifer and the clay layer
separating the upper and lower water-bearing zones, is commonly referred to as the
8-C aquitard. The aquitard has been reported to be between 50 and 100 feet thick in
Santa Clara Valley.
Three local aquifers have been identified through the investigation at AMD 915. (Figure
3). The shallowest of these aquifers has been designated the A aquifer and extends
from 7 to 20 feet below the ground surface. The permeable portion of this unit is
generally from three to five feet thick. The next shallowest unit has been designated
as,the 81 aquifer which is separated from the A aquifer by a relatively impermeable
zone,of silty clays. The 81 generally occurs from 20 to 35 feet below the ground
surface and appears to be lenticular and discontinuous in nature,with highly variable
thickness. The next unit has been designated as the 82 aquifer and is separated from
the 81 aquifer by 12 to 35 feet of silty clay and clayey silt. Depth to the 82'.aquifer
at AMD 915 is highly variable ranging from 38 to 65 feet. Permeable units in the 82
range from 2.9 t012 feet in thickness with an average thickness of 5 fe,et. .
The 83 aquifer is t~e deepest water bearing zone penetrated at the AMD 915 site.
Depth to the 83 aquifer is from 65 to 100 feet below ground surface. The 83 is
composed of clayey silt/silty 'clay, silty very fine to medium sands. The more
Page 6 of 52
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__1 - ..--
REGIONAL
DESIGNATION
---
UNIT-AT TYPICAL.
AMD 915 .,: LITHOLOGY-
. 35"
A ZONE
. .
.-20"
--'
.-15'
---
81 ZONE
-40' ~. -.5'1.
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SCHEMATIC GEOLOGIC
-LOG AMD 915
FIGURE 3
DRAWN BY.
I DATE'
IDRWG. NO.
,
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. .
permeable silty sands vary from 7 to 14 feet in total thickness with an average
thickness of abol:lt10 feet. The 83 most likely represents a group of discontinuous
'sand lens rather than a continuous sand body. Data on the 83 at AMD 915 is limited,
however, based on investigations at other sites, this description would be typical of
water bearing zones at similar position in the stratigraphic geologic column.
. The deeper units have not been investigated at AMD 915 since groundwater
contamination has been limited to the 82 aquifer. 80th regional geologic studies and
investigations at other sites indicate the presence of discontinuous water bearing
zones in the intermediate depths down to about 125 feet. A more continuous sand
layer may occur near this depth. This water. bearing zone, if present, is typically
underlain by a regionally continuous clay layer. The clay layer varies in thickness but
is usually reported to be tens of feet thick. At varying depths below this clay layer are
the thicker sand units that currently provide a large percentage of the local drinking
water supply.
The horizontal groundwater gradient 'in all identified aquifers, in static conditions, is
to the north toward San Francisco 8ay. Local reversal of gradient is observed in the
vicinity of groundwater extraction systems. The vertical hydraulic gradient is generally
upward from the deeper aquifers and this has been verified to be the case at the AMD
. 915 site.
1.6
WATER USE
. Currently, groundwater from this basin provides up to 50% of the municipal drinking
. water for the 1.4 million residents of the Santa Clara Valley. In 1989, groundwater
accounted for approximately 128,000 of the 315,000 acre feet of drinking water
delivered to Santa Clara Valley Water District customers. This water is produced from
the C aquifer. Groundwater contamination is limited to the shallow A and 8 water
bearing zones (see 1.5 above). .
Prior to the conversion of agricultural land throughout the Santa Clara Valley to
industrial use in the late 1960's and early 1970's water in this area served as
irrigation supply and other agricultural purposes. No supply wells completed in the
contaminated shallow aquifers have been identified. On March 30, 1989, the Regional
Board incorporated the State Board'Policy of "Sources of Drinking Water" into the
Basin Plan. The policy provides for a Municipal and Domestic Supply designation for
all waters of the State with some exceptions. Groundwaters of the State are
considered to be suitable or potentially suitable for municipal or domestic supply with
the exception of: 1) the total dissolved solids in the groundwater exceed 3000 mg/L,
and 2) the water source does not provide sufficient water to supply a single well
capable of producing an average, sustained yield of 200 gallons per day. Based on
data submitted by AMD, the RWQCB fin9S that neither of these two exceptions apply
.. to the A and B zones at AMD 915 site. Thus, the A and B zones are considered to be
Page 8 of 52
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potential sources of drinking water. EPA agrees with this determination.
AMD 915 was listed on the National Priorities List (NPL) primarily because of the
potential threat from past chemical releases to the quality of this valuable resource.
The major concern at the site stems from the potential migration of contaminants in
the Upper Aquifer Zone down to the Lower Aquifer Zone through abandoned or poorly
sealed wells or natural conduits through aquitard material. Municipal water supply
wells are generally perforated in the Lower Aquifer Zone. All water supply wells
located within an approximate one mile radius of the AMD 915 site are perforated
from 190 to 390 feet below ground surface.
Currently, the nearest municipal drinking water supply well downgradient of the site
is a Santa Clara Valley Water District well, which is located more than 2000 feet
north of the site. No pollutants have been found in this well to date. Currently, there
are no known users of ground water from the Upper Aquifer Zone. The Regional
Water Quality Control Board (RWQCB) has identified potential beneficial uses of the
shallow ground water underlying and adjacent to the AMD 915 site. These beneficial
uses include industrial process water supply, industrial service water supply, municipal
and domestic water supply and agricultural water supply. These are the same as the
existing and potential beneficial uses of the ground water in the Lower Aquifer Zone.
A well search for abandoned wells in a 3350 acre area encompassing AMD 915 was
completed in December 1986. This includes over one mile in all directions and over
three miles in the downgradient direction. The focus of the well search was to
identify wells that potentially may form migration pathways to the deeper aquifer.
The search identified 177 possible well locations. Of these wells 76 are identifjed as
destroyed. Only four wells that might act as potential migration conduits to deeper
aquifers were identified. Only one of these wells is downgradient of the AMD 915
site. This well is a Santa Clara Valley Water District (SCVWD) well more than 2000
feet downgradient of the site. Testing of the well has shown no evidence of
contamination. Of the remaining three wells, two wells are listed as destroyed in
SCVWD records. The remaining well is a cathodic protection well maintained by
PG&E. This type of well is frequently installed to inhibit rust in underground pipelines.
These wells are typically shallow (Le. pipeline depth) and cased with steel. No
additional data was available on the other well and attempts to field check the well
location were unsuccessful.
Two municipal supply wells were identified by the potential conduit study. WelllD
number 1845 is a City of Sunnyvale water supply well. This well is over 3000 feet
upgradient of the known groundwater contamination plume. Well ID number
T6SR1WS29N2 T6SR1WS29 is also upgradient of the groundwater pollution plume
and is shown in Santa Clara Valley Water District records as destroyed.
The potential conduit survey was updated in 1989 with a new search of Santa Clara
Page 9 of 52
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Valley Water District records to locate any wells that might have been installed since
the completion of the potential conduit search in 1986. This ~econd search found
eight wells, four of which had been destroyed. The remaining four wells are active
monitor wells slotted in the shallow aquifer between 5 and 20 feet below ground
surface. These four wells, due to the shallow depth of completion, do not represent
potential conduits for migration of contaminants to deeper aquifers.
1.7
SURFACE AND SUBSURFACE STRUCTURES
The physical site consists.of approximately five acres. Three physical structures exist
at the surface. The largest of these, designated as AMD 915, covers about 116,000
square feet. The remaining buildings are s~aller each covering less than 10,000
square feet. The remainder of the surface is paved for use as parking or is covered by
concrete utilized in facility support structures. Plants or other forms of landscaping are
minimal.
Eleven chemical storage or treatment areas have been documented at the AMD 915
facility (Figure 4). This has included three underground acid neutralization systems,
two above ground drum storage areas, and six underground tank complexes. Two of
the acid neutralization systems (ANS) remain in place and in operation, one of the
drum storage areas is still active, and two of the underground tank complexes are still
in use. The remainder of the subsurface structures have been removed.
Two tanks have been removed from the Pad III area. A 1,500 gallon steel tank
Installed in 1973 for waste solvent storage, was removed in 1987. Soil samples and
tank integrity testing both indicate that the tank had not leaked. A 400 gallon tank
was installed in 1980 for photo resist stripper waste and was removed in 1983. Soil
samples were taken from the excavation and no contamination, was indicated. The
tank was. visually inspected and no damage or leaks were noted.
The tanks in the Pad IV area were installed in 1976 and removed in 1981 (see 2.1
below). Pad IV had two.1 ,400 gallon, single wall steel tanks,. one for waste solvent
and one for waste photo resist. Additional detail regarding tank integrity and the
removal of these tanks is provided in Section'2.2 below. .
Page 10 of 52 .
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.0
HISTORICAL UNDERGROl
CHEMICAL STORAGE LOCAnc
AT AMD 8UILDING
FIGURE 4 !
-------
Three single wall steel tanks were installed at the Pad VI area in 1980 and an
additional vaulted polyethylene tank was installed in 1982. Two 2000 gallon steel
tanks were used for waste solvent storage. The remaining steel tank, 1,000 gallon,
capacity was used for storage of diesel fuel. The tank installed in 1982 of 500 gallon
capacity was used for storage of waste. photo resist. The 2,000 gallon tanks were
removed in 1986 and the 1,000 gallon tank was removed in 1988. The polyethylene
tank was removed in 1983. The condition of all tanks was reported to be good upon
removal with no evidence of damage or leaks. All three of the steel tanks passed a
tank pressure test for integrity after removal.
Three underground tanks were installed at Tank Farm VI in 1982. Two vaulted steel
tanks, one of 1,000 gallon and one of 1,200 gallon capacity, were used for waste
solvent storage. The third tank was a vaulted polyethylene tank used for waste phot"o
resist storage. The waste photo resist tank was removed in 1987. The two waste
solvent tanks were removed in 1990. All tanks were reported to be in good condition
upon removal.
The three underground acid neutralization systems were installed' sequentially. The C
system was installed in 1974 and consisted of three steel-lined single wall tanks with
a total capacity of 4,200 gallons. The excavation and removal of the C system is
covered in greater detail in Section 2.2 below.
The remaining drum storage area'is an enclosed concrete, contained area (Chemical
Storage III) ~hat was installed in 1982. The two remaining acid neutralization systems,
D system and E system were installed in 1977 and 1979 respectively. Both systems
consist of multiple underground vaulted fiberglass tanks. The D system has a capacity
of 3,600 g~lIons in a three tank system. The E system has a capacity of 24,000
gallons in a, five tank, system. The remaining underground tank areas are Tank Farm
III and Tank, Farm IV. Both areas are used for the temporary storage of waste solvent.-
- Tank Farm III, installed in 1983, contains two vaulted steel tanks one with 2,400
gallon capacity and one with 1,200 gallon capacity. Tank Farm IV, installed in 1982,
contains three vaulted steel tanks one with 2,500 gallon capacity, one with 1,200
gallon capacity, and one with 1,000 gallon capacity.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
. .
. 2.1
HISTORY OF SITE ACTIVITIES
Advanced Micro Devices Building 915 (AMD 915) was built in 1974, and was the first
commercial construction at this site.. This facility was designed and has been used
as a semiconductor fabrication facility from 1974 through the present. The recent
trend has been an increased focus on research and .development activity with a
decline in th_eimportance of production activities. The manufacturing processes at this
Page 12 of 52
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site have involved the use of solvents, caustics, and acids. No metal plating has
occurred at the AMD 91 5 facility. . .
The earliest records of waste storage and handling practices at the AMD 915 facility
are from 1980. These records are not always clear since they include quantities of
some chemicals in use or storage at several AMD facilities. In general, solvent wastes
at AMD 915 were stored in underground tanks; Freon waste, waste oil, sirtyl-etch,
and sorb-all were containerized in 55 gallon drums for offsite disposal. Corrosives
other than chromic acid were neutralized in the on-site acid neutralization system
which discharged to the sanitary sewer system. Process gas was wet scrubbed and
the scrubber effluent was also directed to the acid neutralization system.
The waste solvent and containerized materials were removed from the site by a
licensed carrier for offsite disposal. As handling and storage practices changed the
storage areas for containerized waste has been continually upgraded and underground
tanks have either been replaced with above ground facilities or doubly contained
underground units. Additional detail of past and present storage facilities is presented
in Section 2.2 below.
2.2
HISTORY OF SITE INVESTIGATIONS
Initial investigation at this site began voluntarily in 1981 as the result of soil
contamination discovered during an underground tank excavation and removal. The
removal was due to a change in facility operations. Additional investigations were
driven by ongoing investigations at other AMD facilities. As many as 28 separate
underground tanks may have been in service at various times at the AMD 91.5 site.
The majority of these tanks have been removed from service or replaced with doubly
contained above or below ground units.
Five potential source areas of soil and/or groundwater contamination were
investigated at AMD 915 (Figure 4). These include the Pad IV photoresist stripper tank
removed in 1981, the Pad .C" ANS removed in 1981, solvent tanks at Pad VI
removed in 1986, Pad III waste solvent tank removed in 1987, and the East End
diesel tanks investigated in 1988.
Of the five areas investigated two have been identified as possible sources of soil and
groundwater contamination at the AMD 915 facility. These include an acid
neutralization system north of the AMD 915 building at Pad "C. and the Pad IV
photoresist stripper tank also north of the AMD 915 building. No other signs of
leaking tanks were identified in the removal of tanks from the other three areas. Soil
samples confirm the absence of contaminated soil in the vicinity of the other tanks.
The tank removal at the Pad IV area apparently removed contaminated soil containing
greater than 100 mg/Kg of trichloroethylene (TCE). However, documentation of the
depth of excavation and lateral extent of soil contamination was unavailable.
Additional data collection to investigate remaining potential source soil contamination
was completed in July 1990 as part of the final RI study. The only EPA 8240
Page 13 of 52
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compounds identified during this investigation were 1,2,4- Tricnlorobenzene (1',2,4-
TCB) and 1,2,3-Trichlorobenzene (1,2,3-TCB) at concentrations less than 1 mgfKg (1
ppm in soil). .
During tank removals two leaking underground tanks have been identified. The first
of these occurred during the removal of two, 1500 hundred gallon tanks from the Pad
IV area. The tanks were used for storage of photoresist solution and waste solvent.
Holes in the photoresist tank was observed during the removal of the tanks in 1981.
Based on' soil samples from the excavation. this was verified as a source of
contaminants. It was not possible to determine the duration of the leak or volumef
mass of contaminants released.' .
The second leaking underground tank was one of three in an underground acid
neutralization system (ANS). The leak in this tank from the ANS, located at pad "C",
was documented when a hole was noted in one tank during removal in late 1981. .
These two areas have been identified as potential point sources of contamination.
Based on soil sampling in the exc~vation and groundwater monitoring data, the "C"
ANS was probably the dominant source of groundwater contamination at the AMD
915 site. '.
Groundwater investigation also began in 1982 as part of the investigation of the
leaking underground tanks previously documented. Ongoing extraction of groundwater
through existing building dewatering sumps was supplemented in 1982 with the
addition of the first in a series of groundwater extraction wells. Monitoring of
. groundwater quality has been ongoing, at least quarterly, since 1982.
. .
Additional offsite sources of groundwater contamination may. have a significant affect
on the AMD 915 site.- The most notable of these are Advanced Micro Devices
901 f902 Thompson Drive facilities, Signetics 811 East Arques site, and the FEI
Microwave facility at 825 Stewart Drive. These three facilities have documented point
sources of groundwater contamination which has commingled in the subsurface and
may be commingling with groundwater contamination from the AMD 915 site. Control
of this commingled groundwater contamination plume and cleanup activities are being
addressed under other RWQCB Orders and a .separate Record of Decision.
While investiga.tion and interim remedial actions had been ongoing since 1982 the
formal RemediallnvestigationfFeasibility Study (RifFS) process began with the request
for an RifFS workplan in 1988. A well survey to locate wells in six areas that might
act as potential conduits for the spread of groundwater contamination was
commissioned by an industry' group in 1986. This survey included the area
surrounding the AMD 915 site and was as updated for the AMD 915 RI in 1990.
'For purposes of these reports and' the proposed .final cleanup plan, AMD 915
Deguigne Drive has been designated as a single Operable Unit (see Figure.2). It was
determined that the RI would focus on groundwater data from 1987 to 1989 as a
result of changes in analytical accuracy and sampling protocols. Several draft RifFS
reports have been submitted on' behalf. of AMD including' the draft final RifFS
Page 14 of 52
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submitted in January 1991. Final corrections were added in March"1991. The RWQCB
adopted an Order June 19, 1991 approving the RifFS and a final cleanup plan that
encompassed cleanup at the AMD 915 facility. While all available data was considered
in the FS and the risk assessment, risk management decisions included groundwater
data that was collected after the completion of the FS.
2.3
HISTORY OF ENFORCEMENT ACTIONS
The site has been included on the National Priorities List (NPL) and has been regulated
by Regional Board Orders, as indicated herein:
A. April 1985
B. June 1988
C. May 1989
D. May 1989
E. September 1990
F. December 1990
Order #85-034, Waste Discharge Requirements
Adopted for NPDES Permit CA0028797
AMD 915 Proposed for Inclusion on the NPL
Order #89-043, Administrative Civil Liability for
Late Submittal of RifFS Workplan
Order #89-080 Site Cleanup Requirements
Adopted, Approving RifFS workplan
AMD added to the NPL
Order #90-156, Reissuance of Waste Discharge
Requirements Adopted for issuance and revision
of NPDES Permit CA0028797
G.
June 1991
Order #91-101, Site Cleanup Requirements
Adopted, Approval of Final Cleanup Plan and
Cleanup Standards
3.0 COMMUNITY RELATIONS
3.1
COMMUNITY INVOLVEMENT
An aggressive Community Relations program has been ongoing for all Santa Clara
Valley Superfund sites, including AMD 915. The Board published a notice in the San
Jose Mereu. News on March 13, 20, and 27, 1991, announcing the proposed final
cleanup plan and opportunity for public comment at the Board Hearing of March 20,
1991 in Oakland, and announcing the opportunity for public comment at an evening
public meeting to be held at the Westinghouse Auditorium, Britton at East Duane
Avenue, in the City of Sunnyvale on Thursday March 28, 1991. Based on community
response the 30 day comment period from March 20, 1991 through April 19, 1991
was extended for an additional 30 days through May 20, 1991. Several informal
Page 15 of 52
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meetings were held with c mmunity membersduririg the extended public comment
period.
3.2
FACT SHEETS
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 March 1991, described the cleanup alternatives evaluated,
explained the proposed final cleanup plan; announced opportunities for public
comment at the Board Hearing of March 20, 1991 in Oakland and the Public Meeting
of March 28, 1991 in Sunnyvale and described the availability of further information
at the City of Sunnyvale Library and the Regional Board offices. An additional Fact
Sheet was mailed to. the interested public in July describing the final plan and.
summarizing the response to comments regarding AMD 915.
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 the existing interim remedial
measures. The interim remedial measures have included the removal. of. leaking
underground tanks and acid neutralization systems, containment and extraction of
contaminated groundwater, and treatment of extracted groundwater.
4.1.1 Current Interim Remedial Measure (lRM)
Two interim remedial actions for soil were completed in 1981 . The first of these was
the removal of a waste solvent tank and Burmar vault in the Pad IV area in June
1981. This excavation resulted in the removal of approximately 1500 cubic yards of
soil. Analysis of soil for VOCs was not completed at the time of excavation.
Additional investigation of the Pad IV area in July 1990 indicated that this action was
successful and no soil with greater than 1 ppm of VOCs remain in place. .
The second action was completed in September 1981 with the removal of the acid
neutralization system from the Pad "C" area north of the AMD 915 facility. The acid
neutralization system and approximately 5500 cubic yards of soil were removed
between December 21, 1981 and January 4, 1982. These materials were disposed
of at an offsite commercial disposal facility.
Remediation of the groundwater began with extraction of groundwater from four
building dewatering sumps which were in place from the completion of the 915
building. These sumps only extract water from the shallow or A aquifer and three of
the sumps are still operating at present. In 1982 five groundwater extraction wells
were installed, with four wells extracting water from the A and B1 aquifers and one
well extracting water from the A, B1 and B2 aquifers. In 1984 four additional
extraction wells were completed. These wells were combined with the two best
Page 1 6 of 52
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producing wells that had been installed in 1982 for a total of six extraction wells. The
intent of these changes to the system was to improve control of bffsite contaminant
migration. An additional extraction well completed in the 82 aquifer was added in
1985. An eighth extraction well, again in the B2 aquifer, was added in 1988 (Figure
5). The layout of the existing groundwater extraction system is shown in Figure 6.
The extracted groundwater is piped to a groundwater treatment system, consisting
of two airstripping towers, one active, one reserve, and an aqueous phase activated
carbon filtration unit. This treatment system was completed in January of 1984. The
system has consistently removed from 90 to 99% of the VOCs from the groundwater.
Approximately 30% of the extracted treated groundwater is reused as industrial
process or cooling water, prior to release to the sanitary sewer. The remaining treated
water is discharged to a storm sewer tributary of Calabazas Creek under NPDES
Permit Number CA0028797. The discharge permit was revised in December 1990.
The current permits includes limits for all chemicals of concern in addition to limits for
selected inorganics identified by the RWaCB Basin Plan. These limits generally are set
at the more stringent of the drinking water standards (MCLs) or aquatic toxicity values
(see Table 1).
4.1.2 Selected Remedy
Following completion of the RI it was determined that the IRM for soil had been
successful. No further remedial action for soil is included. The selected remedy for
groundwater is the continued operation of the eight existing groundwater extraction
wells. Treatment by air-stripper with final polish by aqueous phase carbon filtration
will also continue. Onsite reuse of the groundwater is expected to increase in the
future with attendant decreases in discharge to surface water.
The air stripper will include emissions controls if emissions exceed levels permitted by
BAAQMD.
The discharge to surface water is controlled by NPDES Permit No. CA0028797. The
limits for this discharge includes instantaneous maximum limits for specific
contaminants and limits for receiving waters including pH, nitrogen and dissolved
oxygen. The discharge limits were established following EPA guidance and represent
the best available technology. A complete list of discharge limits is included as Table
1.
4.2
ROLE OF THE RESPONSE ACTION
The purpose of the actions at AMD 915 is to control the migration of polluted
groundwater from the site and to capture and remediate existing contaminated
groundwater. The intent of these actions is to expedite cleanup of groundwater at this
site and to prevent movement of contaminated groundwater from the onsite area to
offsite and to prevent potential vertical migration into aquifers that currently serve as
drinking water sources.
Page 17 of 52
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GROUNDWATER TOTAL VOCS CONCSNTRATION CONTOURS
B2-AQUIFER ZONE, APRIL 1991
B»4O "»^
EXPLANATION
(79) TOTAL VOCS CONCENTRATION IN WEUtPfb)
(MD) VOC« NOT OETECTEO M WEU
^ AO* TOTAL VOCS CONCENTRATION CONTOUR
FIGURES
-------
AMD WILL*
•NdVCCMNO-SCKNCCI
WUT1NOHOUSC WtLLS MlAI
*-*
?-• taM *** ••Imtt
AMD 915
EXTRACTION SYSTEM
FIGURE 6
~" '
PROJECT STTE
ADVANCED ftBCftO DEVICES
-------
,.
. .
The IRM for groundwater has contained the groundwatercontar:nination plume to the
site. Vertical migration has been limited and the' toxicity, mobility, and volume of
co.ntaminants has been reduced. The final goal of this response action is to allow the
future use of the shallow groundwater as a possible source of drinking water.
',.
5.1
5.0 SUMMARY OF SITE,CHARACTERISTICS
SOURCES OF CONTAMINATION
5.1.1 Source Investigation
Five potential source areas of soil and/or groundwater contamination were
investigated at AMD 915. These include the Pad IV photoresist stripper tank removed
in 1981, The Pad "Cn ANS removed in 1981, solvent tanks at Pad VI removed in
1986, Pad III waste solvent tank removed'in 1987, and the East End diesel tanks
investigated in 1988.' .
Of the five areas investigated two have been identified as possible sources of soil and
groundwater. contamination at the AMD 915 facility. These include an acid
neutralization system north of the AMD 915 building at Pad "C" and the Pad IV
photoresist stripper tank also north of the AMD 915 building. No other signs of
leaking tanks were identified in the removal of tanks from the other three areas. Soil
samples confirm the absence of contaminated soil in the vicinity of the other tanks.
The tank removal at the Pad IV area apparently removed contaminated soil containing
greater than 100 mg/Kg of trichloroethylene (TCE). However, documentation of the
depth of excavation and lateral extent of soil contamination was unavailable.
.Additional data collection to investigate remaining potential source soil contamination
was completed in July 1990 as part of the final RI study. The only EPA 8240
compounds identified during this investigation were 1,2,4-Trichlorobenzene (1,2,4-
TCB) .and 1 ,2,3-Trichlorobenzene (1 ,2,3-TCB) at concentrations less than 1 mg/Kg (1
ppm in soil). . . . .
Additional offsite sources of groundwater contamination may have a significant affect
on the AMD 915 site. The most notable of these are Advanced Micro Devices
901/902 Thompson Drive facilities, Signetics 811 East Arques site, and the FEI
Microwave facility at 825 Stewart Drive.. These three facilities have documented point
sources of groundwater contamination which has commingled in the subsurface and
may be impinging upon AMD 91 5 groundwater. Control of this commingled
groundwater contamination plume and cleanup activities are being addressed by
separate actions. '.
> Page 20 of 52
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TABLE 1
NPDES DISCHARGE LIMITS, AMD 915
(p.g/l)
VOC's
Instantaneous
Maximum Limit
Constituent
Trichlorofluoromethane
1, 1, l-trichloroethane
Tetrachloroethylene
Trichloroethylene
1,1 Dichloroethylene
Viny1. Chloride
cis-l,2-Dichloroethylene
trans-l,2-Dichloroethylene
Methylene Chloride
Total VOC's
AROMATICS
Ethylbenzene
Dichlorobenzene
Trichlorobenzene
Xylenes
Total Petroleum Hydrocarbons
INORGANICS
Arsenic
Cadmium
Chromium (VI)
Copper
Cyanide
Lead
Mercury
Nickel
Silver
Zinc
'Total of constituents for EPA 601 analytes
Page 21 of 52
5.0
5.0
5.0
5.0
5.0
0.5
5.0
5.0
5.0
10.01
5.0
5.0
5.0
5.0
50.0
20.0
10.0
11.0
20.0
25.0
5.6
1.0
7.1
2.3
58.0
-------
5.2
DESCRIPTION OF CONTAMINATION
5.2.1 Soil Investigations
Soil pollution was the most concentrated near the AMD 915 acid neutralization
system, located just north of the AMD 915 facility. Soil concentrations up to 280,000
ppb of TCE were detected below the western-most tank in the three-tank acid
neutralization system. Concentrations as great as 330,000 ppb of TCB have been
detected in soil borings.
Additional excavation and removal of tanks was carried out at the Pad IV area also
north of the AMD 915 building (Figure 4). Soil samples from this excavation. were
analyzed only for TCB, xylene, toluene, and benzene. The depth of the excavation and
lateral extent of soil contamination was poorly documented, in addition to the absence
of analysis for VOCs. Therefore this was identified as a data gap in early drafts of the
RifFS and additional sampling was completed in July 1990. The only analytes
detected in the soil samples from the additional soil borings were 1,2,4-TCB and
1,2,3-TCB. These analytes were present at levels below 1 mg/Kg and are not
considered to represent significant soil contamination. .
5.2.2 Groundwater Investigations
Groundwater investigation has included the installation of 42 monitoring wells.
Groundwater sampling of selected wells has occurred on a quarterly basis for at least
the last four years. Groundwater monitor data on a less systematic basis is available
for up to 10 years. The characterizations of risk are based on data collected from
1987 through 1989. .
Based on this data the lateral extent of groundwater contamination is limited to the
AMD 915 site. Vertically, VOC contamination has been confirmed down to the B2
aquifer at depths up to 68 feet. Groundwater contamination has not been dete"cted
in the B3 zone. The majority of onsite, Azone monitoring wells are dry, therefore the
lateral extent of contamination in the A zone is difficult to estimate. The lateral extent
of contamination in the recent past has been limited to 250 feet downgradient of the
source area. The spread of the groundwater contamination from the AMD 915 facility~
perpendicular to the groundwater flow direction, can not be determined ~ue the
contaminant contribution from upgradient sources.
The rate of groundwater flow in the shallow aquifers at the AMD 91 5 site, without
. considering the cone of depression resulting from the groundwater extraction system,
. is estimated to vary from 50 to 200 feet per year. Modeling results presented in the
RI/FS indicate that, with the eight extraction wells operating, capture of the
groundwater contamination plume in the shallow aquifers is complete.
TCE is the most prevalent groundwater contaminant and has been utilized as a
indicator chemical for the AMD 915 site (see section 6.1 below). Highest initial levels
Page 22 of 52
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ofTCE contamination were recorded in 1892 in monitor wells 9-S in the A aquifer and
9-D in the B1 aquifer. The maximum concentration of TCE in wel~ 9-S was 4800 I1g/l.
The maximum concentration of TCE in well 9-0 was 6600 I1g/l. These wells were
abandoned in 1988. The last sampling event prior to abandonment for well 9-S was
in October 1987. At this time, 800 119/1 of TCE was detected in well 9-S. The last
sampling event prior to abandonment for well 9-0 was in June 1988 and 1100 I1g11
TCE was detected in well 9-0. The maximum concentration of TCE in July 1990 was
in well 41-D at 990 I1g/l. This well is near the upgradient property boundary and is not
necessarily representative of groundwater contamination related to onsite point
sources.
5.2.3 Air Investigations
Volatilization of groundwater contaminants from the subsurface was not investigated
since the groundwater plume is restricted to subject property. Therefore no current
residential property exists above or adjacent to the plume. The site is completely
paved or covered by structures with active ventilation systems. The paving may limit
the migration of contaminants and the active ventilation systems will limit the
concentration of contaminants in indoor air.
Emissions from the onsite air stripper that is currently part of the interim remedial
action are regulated by the BAAOMD. The air stripper systems at AMD were
permitted by the BAAOMD in 1986. The BAAOMD permit process would usually
result in the request for data and the renewal of the permits on an annual basis. The
permits for the air strippers were inexplicably dropped by the BAAOMD. AMD filed
applications for new permits in May of 1990. Discussions with BAAOMD' staff
indicates that additional information was requested from AMD. The permit to o'perate
for the AMD 915 air strippers was re-issued by the BAAOMD in August 1991. The
permit was not revised since this was not a new or modified system. No risk
screening was required.
The air stripper at AMD 915 releases approximately 1.5 pounds of contaminants,
dominantly TCE, per day. The BAAOMD has not required control of the air stri,.. er
offgas. The potential health risk from the uncontrolled air strippers has been evaluated
by the BAAOMD. Since the air stripper had been previously permitted and is not a
new or modified system the air strippers do meet the requirements of BAAOMD Rule
47. While they release more than one pound per day of volatile organic chemicals
(VOCs) they were permitted in 1986 prior to enactment of newer regulations and are
therefore considered to be in compliance with Rule 47 by a "grandfather" clause.
Air emissions for the AMD facility at 915 OeGuigne Drive (AMD 915) facility have
been evaluated as a whole by BAAQMD as required by Assembly Bill 2508. The levels
of emissions were not considered a great enough health risk by the BAAOMD to
warrant further screening or modeling. An evaluation of the emissions from the air
strippers was submitted by AMD in September 1991. Estimated emissions have
declined to a current level of about 300 pounds per year or 0.82 pounds per day.
Emissions controls will be added to the air stripper at AMD #915 if required by
Page 23 of 52
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BAAQMD.
6.0 SUMMARY OF SITE RISKS
6.1
TOXICITY ASSESSMENT
Using very protective assumptions regarding c'oncentration, distribution, toxicity, and
potential routes of exposure, the Baseline Public Health Evaluation (BPHE) identified
certain .chemicals of potential concern. II The initial list of chemicals of concern
included.all chemicals.that were detected in the chemical database for the period from
1987 through 1989 plus additional data for inorganic analysis from 1990 (see Table
2). This list included twenty organic chemicals and two inorganic chemicals. Twenty-
three analytes are listed since Chromium is included in two valence states.
This list was reduced through consideration of toxicity, occurrence, and the availability
of toxicological data. The revised list consists of 16 organic chemicals and 2 inorganic
chemicals for a total of nineteen chemicals, since Chromium is again included in two
valence states. These chemicals include (see Table 2) Arsenic, Benzene, Chloroform,
Chromium (III), Chromium (VI), Dichlorodifluoromethane (Freon 12), 1,1-
Dichloroethane (1, 1-DCA), 1,1 -Dichloroethylene (1, 1-DCE), cis-1 ,2-Di.chloroethylene
(cis-1 ,2-DCE), trans-1 ,2-Dichloroethylene (trans- 1 , 2-DCE), Ethylbenzene, Freon 113,
Tetrachloroethylene (PCE), Toluene, 1,2,4- TCa, 1,1,1- Trichloroethane (1,1,1- TCA), .
TCE, Trichlorofluromethane (Freon 11), and xylenes.
Arsenic was used in the process at the AMD 915 facility in the form of arsine gas.
The gas was collected by hoods within the facility and sent to scrubbers for removal
from the air prior to release. The scrubber effluent was in turn sent to the acid
neutralization system for treatment prior to discharge to the sanitary sewer system.
Based on this history of site usage and detection in some groundwater samples'
arsenic was included as a chemical of concern included in the FS. Further review of
the'occurrence of arsenic was included in an addendum to the FS submitted in March
1991.
The maximum concentration of arsenic detected was 14 pg/I. This is well below the
MCL of 50 pg/I. Background concentration of arsenic in groundwater in the South Bay
is highly variable, however background in the area near AMD 915 is estimated to be
10 pg/l. The backg~ound is well within the range established for groundwater in the
South Bay. This background concentration was exceeded in only a single sample at
14 pg/l. Since the difference between 10 and 14 pg/l was not considered to be a
significant variation from background and since a small number of samples exceeded
background it was assumed that the occurrence of arsenic is representative of local
background levels in shallow groundwater and not site contamination. Therefore
arsenic was eliminated as a chemical of concern.
The rational for selecting the remaining chemicals as chemicals of concern is as
follows:
1.
Chloroform,
Chromium
(VI),
1,1-Dichloroethane
(1,1-DCA),
1,1-
Page 24 of 52
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Dichloroethylene (1, 1-DCE), Tetrachloroethylene (PCE), and TCE are known or
possible human carcinogens. .
2.
All of the chemicals of concern are detected in groundwater at a greater than
10% frequency.
3.
Chloroform, Dichlorodifluoromethane (Freon 12), 1 , 1-Dichloroethane (1, 1-DCA),
1, 1-Dichloroethylene (1, 1-DCE), cis-1 ,2-Dichloroethylene (cis-1 ,2-DCE), trans-
1,2-Dichloroethylene (trans-1 ,2-DCE), Ethylbenzene, Freon 113,
tetrachloroethylene (PCE), Toluene, 1,1, 1-Trichloroethane (1,1, 1-TCA), TCE,
Trichlorofluromethane (Freon 11), and xylenes possess physicochemical
properties (relatively high water solubility and relatively low soil sorption) which
promote their dispersion in groundwater. In addition all of these chemicals are
volatile and can easily be dispersed into soil gas and possibly the atmosphere.
4.
Chromium. '"'ichlorodifluoromethane (Freon 12), Ethylbenzene, Freon 113,
Tetrachlorc ylene (PCE), Toluene, 1,2,4-TCB, 1,1, 1-Trichloroethane (1,1,1-
TCA), TCE, " l'ichlorofluromethane (Freon 11), and xylenes have been used on
site as part of the manufacturing process. Soil sampling has documented the
presence of most of these chemicals as contaminants in soil from source area
excavations.
5.
TCE has been used as an indicator chemical for the site. This is based on the
reasons stated above. TCE is also the chemical most frequently detected in soil
and groundwater. TCE has been detected in groundwater at the greatest
concentration of any of the chemicals of concern, has the most widespread
occurrence and has the highest representative or average concentration in
groundwater samples.
6.
Vinyl Chloride has been added as a chemical of concern because it is a known
human carcinogen and a breakdown product of PCE, TCE, and DCE. Vinyl
Chloride has not currently been detected in groundwater or soil at the AMD
915 site.
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TABLE 2
AMD 915 DATA SUMMARY
'.
GROUNDW A TER (Pg/L) SOIL (pg/L)
Chemic:al CRAVE Rep Value Max Value #DeI/lAnai Rep Value Max Value lDeI/IAnaI
Anealc A 10.97 14.1 6121 ND ND 0/14
Benzene A ND ND 0/9 104.89 460 12/18
Chlorofonn B2 1..54 U 111126 ND ND' 0/14.
Chiomium(111) D 93.63 6S3 16/21 ND ND 0/14
Chromium(V1) A 93.63 6S3 16121 ND ND 0/14
Dibfomochloromethanl -
81 0.90 1.80 1/126. ND ND 0/14
Dic:hlorodiftuorornethane D 23 37 2/126 ND ND 0/14
I,I-Dic:hloroethane 82 1.93 4.5 17/126 ND' ND 0114
',I-Dic:hloroethene C 7.90 50 36/126 ND ND 0/14
c:ia-I,1-Dic:hloroethene D 85.04 450 79/126 ND ND 0114
tra..-I,2-Dic:hloroethene D 1.27 2.1 7/126 ND ND 0/14
c:ia-I,3- Dichloropropaneo D 375 750 1/126 ND ND 0/14
Ethylbcnzene D ND ND 0/9 50 100 1/4
Freon 113 D 24.8 280 73/126 1,634.69 9600 32/45
Tetl1lc:hlorethane 82 0.95 1.9 1/126 19.00 38 1/14
Toluene D 2.00 4 119 24.5 110 11118
Total Tric:hlorobenzene" D NA NA NA 8258.82 96,000 43m
Tric:hlorobenzenet D NA NA NA 3512.50 36,000 9/16
(specified al no( 1,2,4-
ilOmer)
1,2,4- Tric:hlorobenzene D t.8 Hi 1/5 7,433.04 60,000 44/83
I,I,I-Trichloroethane D 13.33 44 41/126 0.70 0.7 2/49
Tric:hloroethene . 82 252.67 3,800 105/126 643.97 2,800 39/49
Tric:hloroftuoromethane D 0.88 1.2 4/126 ND ND 0/14
Xylene D ND ND 0/9 92.31 310 14/17
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6.2
RISK CHARACTERIZATION
Using protective assumptions, the BPHE developed current and future exposure
scenarios. This consideration included soil, air and groundwater as potential sources,
transport media, and human exposure points. Risks were characterized for pathways
involving these media in the following subsections. As described in the National
Contingency Plan, the EP A acceptable excess cancer risk range is 1 X 10.4 to 1 X 10.8
for exposure to known or expected carcinogens at concentration levels that represent
an excess upper bound lifetime cancer risk to an individual. For noncarcinogenic
effects, the Hazard Index (HI) provides a useful reference point for gauging the
potential significance of multiple contaminant exposures within a single media or
across media. EPA considers an HI less than 1.0 to be acceptable.
At the AMD 915 site no probable current exposure scenarios have been identified. For
the hypothetical future exposure scenarios, it was assumed that the AMD 915 site
would be developed for residential use and that the groundwater in the shallow aquifer
would be used as the sole source of drinking and domestic water at this site.
According to the BPHE, potential future exposure routes at the AMD 915 site may
include ingestion of groundwater, inhalation of VOC vapors during showering or other
domestic uses, and ingestion of soil during construction of this hypothetical residential
development.
Surface water was not evaluated as a potential exposure pathway since it is
improbable that the contaminated groundwater would reach any body of surface
water. The nearest surface water bodies are the Sunnyvale East Drainage Channel and
Calabazas Creek. The Sunnyvale Drainage channel, approximately 2500 feet west of
the site, is lined. Infiltration of contaminated groundwater from the AMD 915 site into
this channel is unlikely due to the lining and the groundwater flow direction. Calabazas
Creek is approximately 5000 feet east of the site. This section of the creek has been
straightened and lined for flood control purposes. Infiltration of contaminated
groundwater from the AMD 915 site into Calabazas Creek is unlikely due to the lining
and the groundwater flow direction. The nearest surface water body in the
downgradient direction is Guadelupe Slough, more than 10,000 feet north of the AMD
915 contaminant plume. Contaminant migration to Guadelupe Slough would probably
require more than 50 years if groundwater extraction were to cease.
6.2.1 Soil
No shallow contaminated soil remains since the interim remedial actions for soil were
effective. The exposure to contaminated soil through the dermal contact route was
not evaluated since it is unlikely that the chemicals of concern at AMD 915, metals
or VOCs, would be adsorbed through the skin since the VOCs would volatilize into the
air prior to significant subcutaneous adsorption and metals are poorly adsorbed
Page 27 of 52
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through the skin.
Incidental ingestion of soil by a construction worker during hypothetical future
construction on the site was evaluated . The hazard index for exposure to the
chemicals of concern by this pathway is 0.01 for the maximum case indicating that
adverse non-carcinogenic health affects are unlikely to occur. The cancer risk resulting
from exposure through this pathway is estimated to be 1.5 x 10-9. In consideration
of the small population of construction workers that would be exposed the cancer risk
would be statistically insignificant. "
6.2.3 Air
The risk from overall air emissions from AMD 915 was evaluated by the BAAOMD as
part of an evaluation required by California Assembly Bill 2508 (AB 2508). This
evaluation ranked 'the air emissions from AMD 915 .as a medium risk which required
no further modeling or evaluation. It should be stressed that this evaluation is for all
air emissions from the AMD 915 facility to which the air stripper offgas contributes
a small percentage.
The potential for volatilization of chemicals from groundwater to the surface was also
evaluated. Investigations at a neighboring site and at a site in Massachusetts have
indicated that this pathway is probably only of concern in the circumstance where the
vapors enter structures and become concentrated in indoor air. Since the groundwater
contaminant plume is currently contained onsite no residences overlay the plume. The
manufacturing facilities that overlay the plume all utilize active ventilation systems
which would act in two ways to, reduce this potential risk. First the ventilation
system, by pumping air into the structure, creates positive pressure thus reducing the
rate of infiltration of contaminants into the structure and second the continued influx
of air dilutes any contaminants that do enter the structure.
In the hypothetical future case that the site would be re-developed as residential
property this exposure pathway would have a minor contribution (less than 1 %) to the
total risk related to using the contaminated groundwater as a domestic water supply.
Therefore this pathway was not evaluated further.
The emissions and risk related to the releases to ambient air from the air stripper at
AMD 915 were re-evaluated by AMD in September 1991. Both the flow rate and
influent concentration have declined in the last year. This results in reductions in both
mass emission and air effluent concentration. Risk estimates based on this revised
data using a model developed by California Air Pollution Control Officers Association
would predict a risk of less than 1 x 10-5 from this emission. Air effluent control, in
the form of vapor phase activated carbon, will be added to the air stripper in the
future if required by changes in BAAQMD regulations.
.-,
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6.3.3 Groundwater
Possible exposure to contaminated groundwater as a result of using this groundwater
as a source of domestic water supply was evaluated. This evaluation considered both
. direct ingestion of the groundwater and exposure to contaminants through the
inhalation pathway as a result of showering and other domestic use. According to the
BPHE, if no further cleanup action were taken, and if current cleanup actions were
halted, no average exposure scenarios were shown to present a non-carcinogenic or
carcinogenic risk greater than the EPA allowable risk range. Based on average
groundwater contaminant concentration data, the carcinogenic risk from groundwater
ingestion is estimated to be 6 per 100,000 (Table 3). The majority of this risk is
related to the ingestion of arsenic at concentrations well below the Federal and State
maximum contaminant levels (MCLs). The noncarcinogenic hazard index for the
average case is less than 1 indicating that toxic health affects would not be expected
from the domestic use of this groundwater.
A slightly elevated carcinogenic risk and an elevated hazard index is shown for the
maximum exposure scenario. The difference between the two exposure scenarios is
that the average case assumes that an adult consumes 1.4 liters of contaminated
groundwater water every day for nine years and the maximum case assumes that an
adult consumes 2.0 liters of contaminated gr~undwater water every day for 30 years.
Nine years is the 50th percentile residence time and 30 years is the 90th percentile
residence time at one location based on recent census data. The risk for the maximum
scenario, including both ingestion and inhalation exposures, is 1.25 x 10-3 (Table 3)
with a hazard index of 5. The risk without the inclusion of arsenic or the inclusion of
1, 1-DCE as a carcinogen for all pathways would be 5.40 x 10-4 with a hazard. index
of about 6. The hazard index increases as a result of the use of a modified reference
dose for 1, 1-DCE as specified by EPA Region IX staff toxicologist.
It should be emphasized that there are currently no known plans to use the on-site
area for residential purposes. Nor is shallow groundwater currently used for local
drinking water; local ordinances require the installation of a sanitary seal through at
least the upper 50 feet of the shallow water bearing zones. This would limit use of the
most contaminated groundwater for drinking water. In addition, the assumption that
all cleanup actions will be discontinued is intended only to provide a baseline for
comparison, and does not reflect the current situation or future plans for the AMD
915 site.
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TABLE 3
ADULT CARCINOGENIC RISK
AMD 915
CHEMICAL REPRESENT A TIVE EXPOSURE MAXIMUM EXPOSURE
INGESTION INHALATION TOTAL INGESTION INHALATION TOTAL
I
ARSENIC 4~61 X 10" NA. 4.61 X 10" 2.82 X 10~ NA 2.82 X 10~
CHLOROFORM 2.25 X 10" 4.36 X 10" 2.69 X 10" 3.00 X 10.7 9.36 X 10" 3.93 X 10.7
CHROMIUM VI 0.00 X 10" NA 0.00 X 10" 0.00 X 10" NA 0.00 X 10"
1,I-DCA 4;22 X 10.7 0.00 X 10" 4.22 X 10.7 4.68 X 10" 0.00 X 10" 4.68 X 10"
1,I-DCE 1.14 X 10" 1. 76 X 10" 1.32 X 10'" 3.43 X 10" 8.52 X 10" 4.28 X 10~
PCE 1.16 X 10.7 5.79 X 10.1. 1.17 X 10.7 1.11 X 10" 8.90 X 10" 1.12 X 10"
TCE 6.67 X 10" 4.76 X 10.7 7.15 X 10" 4.78 X 10" 5.50 X 10" 5.33 X 10~
TOTAL 6.47 X 10" 2.24 X 10" 6.70 X 10'" 1.11 X 10" 1.40 XI0~ 1.25 X 10"
W/O ARSENIC 1.86 X 10" . 2.24 X 10" 2.08 X 10'" 8.28 X 10" . 1.40 X 10~ 9.68 X 10~
W/O ARSENIC 7.20 X 10" 4.80 X 10.7 7.68 X 10" 4.85 X 10~ 5.48 X 10'" 5.40 X 10~
OR 1,I-DCE
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6.3
PRESENCE OF SENSITIVE HUMAN POPULATIONS
AMD 915 is located in an industrial area and the groundwater contamination plume
has been contained onsite. There are no residences above the groundwater plume.
The San Miguel School, which currently houses a daycare center and a Headstart
Program, is approximately 2000 feet north of the plume boundary. The nearest
residences are more than 500 feet from the site boundary. There are also no public
parks, hospitals, or convalescent homes within or near the plume boundaries.
6.4
PRESENCE OF SENSITIVE ECOLOGICAL SYSTEMS
Two endangered species are reported to use South San Francisco Bay, located
approximately three miles north of the Study Area. The California clapper rail and the
salt marsh harvest mouse are reported to exist in the tidal marshes of the Bay and
bayshore. The endangered California brown pelican is occasionally seen in the Bay
Area, but does not nest in the South Bay. Ranges of the endangered American
peregrine falcon and southern bald eagle include the Bay Area. The southern bald
eagle does not use bay and bayshore habitats. The peregrine falcon is making a strong
recovery and may be downgraded from endangered to threatened status in specific
areas including California in the near future. Nesting peregrines have been noted in the
northern bay area, including the Golden Gate Bridge and Bay Bridge, however nesting
peregrine falcons have not been reported in the South Bay.
The AMD site Study Area does not constitute critical habitat for endangered species
nor does it include or impact any "wetlands". The closest wetlands are about two
miles to the north.
6.5
CONCLUSION
Actual or threatened releases of hazardous substances from the Advanced Micro
Devices, 915 DeGuigne Drive Superfund 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 in the Study Area pose significant health risks as
carcinogens or as noncarcinogens and complete exposure pathways exist, EPA has
determined that remediation is warranted.
7.0 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
Under Section 121 (d)(1) of CERCLA, ~ 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
Page 31 of 52
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standards, requirements, limitations, or criteria that are "appHcable or relevant and
appropriateW under the circumstances of the release. These requirements, known as
W ARARsw, may be waived in certain instances, as stated in Section 121 (d)(4) of
CERCLA, 42 U.S.C. ~ 9621 (d)(4).
WApplicablew 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 CERCLAsite. wRelevant and appropriate" requirements 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
8applicablew 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,
'986).
The determination of which requirements are "relevant and appropriate" 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 reql:Jirements
need be followed. If no ARAR covers a particular situation, or if an ARAR ~s 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. .. . . . .
7.1
TYPES OF ARARS .
There are three types of ARARs. The first type includes "contaminant specificw
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.
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ARARs must be identified on a site-specific basis from inform'ation about specific
chemicals at the site, specific features of the site location, and actions that are being
considered as remedies.
7.2
caNT AMINANT-SPECIFIC ARARS AND TBCS
Section 1412 of the Safe Drinking Water Act. 42 U. S. C. Section 300G-1
Under the authority of Section 1412 of the Safe Drinking Water Act, Maximum
Contaminant levels 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 ~300.400 (g)(2).
The appropriate remedial goal for each indicator chemical in ground water is the MCLG
(if not equal to zero), the federal MCL, or the State MCL, whichever is most stringent.
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.
The FS evaluated groundwater cleanup to background or non-detect levels. Cleanup
to non-detect levels would increase estimated groundwater cleanup times by over
50% and add significantly to cost. The FS also evaluated cleanup levels necessary to
achieve a 1 in 1,000,000 excess cancer risk from future ingestion of the
groundwater. This is highly impractical due to the presence of arsenic. The arsenic
concentration would have to be reduced to 1.5 pg/l to approach the 1 in a 1,000,000
excess cancer risk. This is far below the current MCL for arsenic of 50 pg/l and is
probably below the naturally occurring background of arsenic in groundwater in Santa
Clara County.
....
In addition, cleanup of groundwater to below the MCL for the chemicals of concern
may not be achievable due to the technical difficulties in restoring aquifers by the
removal of low concentrations of any vac. This is due to the slow desorption of
vacs adsorbed to the inner pore spaces of soil particles which make up the aquifer
material and vacs adsorbed to clays and organic matter in the aquitard. Cleanup to
MCl levels would protect the primary beneficial use of the groundwater as a potential
source of drinking water. For these reasons, MCLs were accepted as concentrations
that meet the intent of Resolution No. 68-16.
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7.3
ACTION SPECIFIC ARARS AND TBCS
National Pollutant Discharae Elimination Svstem (NPDES)
NPDES substantive permit requirements and/or RWaCB Waste Discharge
Requirements (WDRs) are potential ARARs for effluent discharges. The effluent
limitations and monitoring requirements of an NPDES permit or WDRs 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 or best available technology standards.
EPA Office of Solid Waste and Emergencv 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 Decisions (RODs), Significant Differences to a ROD and Consent Decrees.
AMD 915 is in an ozone non-attainment area. This directive 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 precedeflce over the
directive.. ' "
Bav Area Air Qualitv Management District (BAAQMD> Regulation 8. Rule 47
Bay Area Air Quality Management District Board of Directors adopted Regulation 8,
Rule 47. This rule is entitled "Air Stripping and Soil Vapor Extraction Operations" and
applies to new and modified operations. The rule consists of two standards:.
o
Individual air stripping and soil vapor extraction operations emitting benzene,
vinyl c~loride, perchloroethylene,' 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. '
o
Individual airstripping and soil vapor extraction operations emitting greater than
.' ~ifteen pounds per day of organic compounds other than those listed above are
r~quired to control emissions by at least ninety percent by weight.
Regulation'S, Rule 47 is an ARAR for the implementation of the remedy at AMD 915.
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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 Calabazas Creek, Guadelupe Slough and other tributary streams and
marshes.
8.0 DESCRIPTION OF ALTERNATIVES
8.1
REMEDIAL ACTION OBJECTIVES
Cleanup of groundwater contamination at the AMD 915 Superfund site focuses on the
following remedial objectives:
1.
Prevention of the near-term and future exposure of human receptors to
contaminated groundwater;
2.
Restoration of the contaminated groundwater for future use as a potential
source of drinking water;
3.
Control of contaminant migration;
4.
Monitoring of contaminant concentrations in groundwater to observe the
control of contaminant migration and the progress of cleanup.
8.2
GROUNDWATER CLEANUP STANDARDS
The cleanup standards must meet all applicable, relevant and appropriate requirements
(ARARs) and be protective of human health and the environment. Based on the results
of the RI no further soil remediation is anticipated.
After further review it was determined that arsenic was not present at concentrations
or in frequency of occurrence that could be considered to be significantly different
from background levels of arsenic. Therefore no cleanup standard for arsenic is
included. Cleanup standards for groundwater are shown in Tables 4 and 5. The
standards for chemicals of concern identified at AMD 915 except fer
dichlorodifluoromethane (Freon 12) shall be the more stringent of the Federal or
California maximum contaminant level (MCLs) for drinking water. The cleanup
standard for Freon 12 is based on Federal ambient water quality crite,ia (WaC). Since
groundwater cleanup levels are based on Federal or State MCLs or Federal wac, this
will satisfy all ARARs for groundwater cleanup.
Tables 4 and 5 show the hazard indices and risk calculations for the chemicals of
Page 35 of 52
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concern at the cleanup standards. These tables include vinyl chloride even though it
has not currently been detected at the site since it is a known human carcinogen and
is a breakdown product of other chemicals detected in groundwater at the AMD 915
site. As an extra measure of protection, the potential risk and hazard related to use
of water as a domestic supply after the cleanup standards have been met has been
evaluated assuming a 70 year lifetime exposure. The noncarcinogenic hazard index
for the sixteen chemicals of concern assuming that all sixteen chemicals are present
at the cleanup standards set for the AMD 915 Superfund site is 1. The excess cancer
risk predicted as a result of inhalation and ingestion of groundwater containing the six
chemicals of concern that are known or suspected carcinogens is 6.19 X 10.4. While
Chromium VI is a chemical of concern and is a known human carcinogen it is not.
included in the calculation of carcinogenic risk since it is not a carcinogen through the
ingestion pathway. Since Chromium VI is not volatile it would not result in an
exposure through the inhalation route in a domestic use scenario.
The health hazard and risk estimates above include 1, 1-DCE which is classified by the
EPA only as a possible human carcinogen. This classification is currently under review
and the California Department of Health Services (DOHS) does not recommend
including 1, 1-DCE in risk calculations as a carcinogen. Based on the recommendation
of DOHS and with guidance from EPA Region IX the risk after cleanup has also been
evaluated without the inclusion of 1, 1-DCE as a carcinogen. Under EPA Region IX
guidance 1, 1-DCE is summed in the hazard index with a more protective reference
dose to provide additional consideration of possible carcinogenic effects.At AMD 915
the carcinogenic risk after cleanup for all chemical of concern associated with the,
potential future use scenario of 70 years of groundwater ingestion and inhalation of
VOCs is 3.1 x 10.4. The adjusted hazard index would be greater than 1, which
indicates that it is more appropriate to include 1, 1-DCE as a carcinogen for this case
and to consider the risk and hazard figures cited above as representative for the AMD
915 site. '
In cleaning up TCE and 1, 1 ~DCE, the dominant chemicals ,in mass and concentration,
to their respective MCls of 5.0 pg/I and 6.0 pg/I, it is quite likely that the
, concentrations of other VOCs will be reduced to levels below the cleanup criteria.
Therefore an additional risk estimate, based on cleanup to MCl levels or current
maximum concentration when these maximum concentrations are less than MCls has
been developed (Table 6). This is an attempt to provide a more realistic estimate of
the residu~1 risk after cleanup is achieved.
The noncarcinogenic hazard index associated with the cleanup standards at AMD 915
for the representative or average case is 0.25 and 0.36 for the maximum case. This
is indicative that no toxic effects, would 'be expected from the domestic use of
groundwater after cleanup at the AMD 915 facility.
The health hazard and risk estimates above include 1, 1-DCE which is classified by the
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EPA only as a possible human carcinogen. Based on the recommendation of DOHS
and with guidance from EPA Region IX as detailed above the risk after cleanup has
also been evaluated without the inclusion of 1, 1-DCE as a carcinogen. The
carcinogenic risk without 1, 1-DCE is 4 x 10-6 for the average or representative case
and 2 x 10-6 for the maximum plausible case. The revised hazard indices are 0.37 for
the average case and 0.53 for the maximum case. The maximum case was considered
in setting cleanup standards.
The compliance boundary includes all groundwater within the plume boundaries as
indicated in Figure 5, all groundwater monitored in existing wells, and any
contaminated groundwater identified by additional monitoring wells installed upon
RWaCB or EPA request for the purpose of monitoring potential vertical or horizontal
migration of groundwater contaminant plumes currently located in the A and B aquifer
zones.
8.3
REMEDIAL ACTION ALTERNATIVES
Initially, a large number of cleanup methods (technologies) were screened with respect
to their effectiveness, implementability, and order-of-magnitude cost. The methods
which passed this initial screening were then combined into cleanup alternatives most
applicable to the AMD 915 site and evaluated in detail. As listed below these include
cessation of remedial action, monitoring, and institutional controls for the onsite area,
groundwater extraction with treatment of the extracted water by air stripping with
polish by carbon adsorption, groundwater extraction with treatment of the extracted
water by carbon adsorption, and groundwater extraction with treatment of the
extracted water by UV/H202 Oxidation. .
Alternative 1: No Action - Monitoring The no action alternative includes completely
stopping operation of the existing groundwater treatment system which has been
operating for the last 6 years and imposes site restrictions on future use of the
property. Contaminant concentration would be reduced by the natural processes of
physical and chemical degradation and dispersion as the plume continued to migrate
north toward San Francisco Bay. Since it is uncertain when the groundwater would
return to background levels groundwater monitoring would continue.
Alternative 2: Extraction - Air StriDDina and liauid Phase Carbon Adsorction This
alternative comprises the current interim remedial system for the groundwater
(extraction wells, air stripper and liquid phase carbon adsorption). Air stripping as a
stand-alone technology is very effective in removing VOCs from groundwater at the
AMD 915 site. Further polishing of the air stripper effluent by carbon adsorption
provides additional treatment. The treatment, reuse, and discharge of the treated
groundwater will continue to be regulated by the RWaCB under an NPDES permit. Air
emissions will continue to be regulated by the BAAQMD. Deed restrictions would be
included to prevent use of A and B zone groundwater while remediation is underway.
Page 37 of 52
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TABLE 4, HAZARD INDEX AT CLEANUP STANDARDS
I
AMD9lS HAZARD INDEX, CONCENTRATION (Cw) SET AT ARARs
, HAZARD INDEX ID CDIIRID CDI = Chronic Daily Intake RID - Reference, Dose
Cw = ARARs, TRes, or cleanup goals
ORAL Inhalation Inhalation TOTAL HI
RID RID HI
No. CHEMICAL Cw 11111 WOE cm HI
I CHLOROFORM 0.100 MCL\B2 0.01 2.86e-03 2.B~1 NA,'. 0.00 2.8~1
2 CHROMIUM m 0.050 MCL\D I 1.430-03 1.43e-03 NA 0.00 1.43e-03 '
3 CHROMIUM VI O.OSO MCL\D O.OOS 1.4Je.~3 2.B6e~1 NA 0.00 2.86e~1
4 DICHLORODIFLUOROMETHANE 0.00019 WQC\D 0.200 S .43e-06 . 2.7Ie~S O.OS 1.09~ 1.36e~
S I,I-DCA O.OOS CA MCL\B2 0.100 1.43e~ 1.43e-03 0.1 1.43e~3 2.86e~3
6 I,I-DCE 0.006 CA MCL\C 0.009 1.7Ie~ 1.9Oe~ NA 0.00 1.9Oe~
7 cis-I,2-DCE 0.006 CA MCL\D 0.02 1.7Ie~ 8.S7e-03 NA 0.00 8.S7e~3
8 Iranl-I,2-DCE 0.010 CA MCL\D 0.02 2.86e~ 1.43e~ NA 0.00 1.43e~
9 FREON 113 ' 1.200 CA MCL\D 3 3.43e,02 1.14e~2 NA 0.00 1.14e~
10 PeE 0.005 MCL\B2 0.01 1.43e~ 1.43e~ NA 0.00 1.4Je.~2
.
II TOLUENE 2.000 MCL\D 0.3 S.7Ie~ 1.9Oe~1 0.6 9.S2e~ 2.86e-01
12. 1,2,4-TCB 0.009 MCL\D . , 0.02 2.S7e~ 1.2ge~ 0.003 8.S7e~ ' 9.86e~
13 I,I,I-TCA 0.200 MCL\D 0.09 S.71e-03 6.3Se~ 0.3 1.90e~ 8.2Se~
14 TCE O.OOS MCL\B2. NA 1.43e~ 0.00 NA 0.00 0.00
IS TRICHLOROFLOUROMETHANE O.ISO CA MCL\NA 0.3 4.2ge-03 1.43~ 0.01 2.14e~ 3.S7e~
16 VINYL CHLORIDE O.OOOS CA MCL\A NA 1.43e-OS 0.00 NA 0.00 0.00
TOTAL HAZARD INDEX '" .92eOO 2.23e-01 le+OO
IRIS - IRIS ORAL REfERENCE DOSE
DWHA - DRINKING WATER HEALTH ADVISORY
WQC - NATIONAL AMBIENI' W ATEIl QUALITY CRITERIA FOR PUBLIC
HEALTH
Page 38 of 52
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MCL - FEDERAL MCL
CA MCL - CALIFORNIA MCL
WOE - WEIGHT OP EVIDENCE - SOURCE OP DATA
A - KNOWN HUMAN CARCINOOENS I
B I - PROBABLE HUMAN CARCINOOEN (limiled human evidence, Idequate evidence from Inlmall)
B2 - PROBABLE HUMAN CARCINOOEN (inadequate human evidence, adequate evidence from Inlmala)
C - POssmLE HUMAN CARCINOOEN (lImited evidence of.careinogenity, anlmalatudiea only)
TABLE 5, CANCER RISK AT CLEANUP STANDARDS
AMD 915 CHEMICAL CONCENTRATION SET TO CLEANUP STANDARDS
DETERMINATION OF EXCESS LIFETIME CANCER RISK FOR CARCINOGENS
EXCESS LIFETIME CANCER RISK = cm It q.
q. = CANCER POTENCY FACTOR (MGIKGfDAY)-1 cm = Chronic Daily k'"ke (MGIKG)
Cw = ARARs, TBCs, or cleanup goals
CHEMICAL Cw WOE\CLASS OF ORAL q. cm RISK INHALATION INHALATION TOTAL
MGIL CARCINOGEN q. RISK RISK
CHLOROFORM 0.100 IRIS\B2 6. IOe-03 2. 86e-03 1.7 4e-05 8.IOe-02 2.3Ie-04 2.4ge-04
I,I-DCA 0.005 CA MCL\B2 9.10e-02 1.43e-04 1.30e-05 NA 0.00 1.30e-05
I,I-DCE 0.006 CA MCL\C 6.00e-01 I. 71 e-04 1.03e-04 1.20e+00 2. 06e-04 3.0ge-04
PCE 0.005 MCL\B2 5.IOe-02 1.4 3e-04 7. 2ge-06 3.30e-03 4.71e-07 7.76e-06
TCE 0.005 MCL\B2 1.I0e-02 1.43e-04 1.57e-06 1.70e-02 2.43e-06 . 4.00e-06
VINYL CHLORIDE 0.0005 CA MCL\A 2.30<: i I. 43e-05 3;2ge-05 2.95e-01 4.2Ie-06 3.71e-05
EXCESS CANCER RISK I. 75e-04 4.44e-04 6. 1ge-04
EXCESS CANCER RISK WIO I,I-DCE 7.20e-05 2. 38e-04 3. 10e-04
WOE = WEIGHT OF EVIDENCE = SOURCE OF DATA
Page 39 of 52
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MCL - FEDERAL DRINKING WATER MAXIMUM ~NTAMINANT
LEVEL
CAMCL - CALIFORNIA DRINKING WATER MAXIMUM "CONTAMINANT LEVEL
A - KNOWN HUMAN CARCINOGENS I I
Bl - PROBABLE HUMAN CARCINOGEN (limited human evidence, adequate evidence from animals)
B2 - PROBABLE HUMAN CARCINOGEN (inadequate human evidence, adequate evidence from animals)
C =' POSSIBLE HUMAN CARCINOGEN (limited evidence of carcinogenity; animal studies only) .
I
Page 40 of 52
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Alternative 3: Extraction - Carbon Adsorotion Alternative This alternative consists
of extraction of groundwater using the current well system. The extracted
groundwater could then be passed directly through granular activated carbon designed
for liquid phase adsorption of VOCs. Use of the air stripper would be discontinued.
The treatment, reuse, and discharge of the treated groundwater will continue to be
regulated by the RWaCB under an NPDES permit. Deed restrictions would be included
to prevent use of A and B zone groundwater while remediation is underway.
Alternative 4: Extraction - UV IH2Q2 Oxidation This alternative consists of extraction
of groundwater using the current network of wells. Oxidation enhancers such as
hydrogen peroxide (H202) would be mixed with the groundwater which is then
exposed to ultraviolet light in the reactor. The reactor offgas would be treated by a
catalytic oxidizer to ensure compliance. The treated groundwater would be recycled
into onsite operations and the excess disposed of to the storm drain. The treatment,
reuse, and discharge of the treated groundwater would continue to be regulated by
the RWaCB under an NPDES permit. Air emissions will continue to be regulated by
the BAAaMD. Deed restrictions would be included to prevent use of A and B zone
groundwater while remediation is underway.
9.0 COMPARATIVE ANALYSIS OF ALTERNATIVES
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.
9.1
CRITERIA
The alternatives were evaluated using nine component criteria. These criteria, which
are listed below, are derived from requirements 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.
4.
Compliance with ARARs (ARARs are detailed in Section 7.0).
5.
Use of treatment to achieve a reduction in the toxicity, mobility or volume of
the contaminants.
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TABLE 6
HEALm INDICES AND CANCER ~K FOR CLEANUP STANDARDS OR CURRENT MAXIMUM CONCENTRATIONS.
CHEMICAL
CHLOROFORM
CHROMIUM (III)
CHROMIUM (VI)
FREON 12
1,I-DICHLOROETHANE
1,I-DiCHLOROETHENE
cis-I,2-DlCHLOROETHENE
Irans-I,2-DlCHLOROETHENE
FREON 113
TETRACHLORETHANE
TOLUENE
1,2,4- TRICHLOROBENZENE
.I,I,I-TRICHLOROETHANE
TRICHLOROETHENE
TRlCHLOROFLUOROMETHANE
VINYL CHLORIDE
TOTAL
.. . .. d.." ..... .......... ..' ..... . ....
...b~~J~~Tij;:89R~~R...~t~1:....
.. ..
CONCENTRATION
Itgll .
4.3
0.19
4.5
6.0
6.0
2.1
260
1.9
4.0
3.6
44
5.0
1.2
0.5
REFERENCE
EPA MCL/MCLG CANCER RISK HAZARDIND~X
(pROPOSED)
100.0 3.94 It 10.7 0.01
50.0 0.9 0.001
50.0 NA 0.3
NA NA 0.00003
5.0 4.68 It 10-6 0.001
7.0 5.13 It 10" . 0.02
(70.0) NA 0;009
(I~.O) NA 0.003
1200 NA 0.0003
5 1.12 It 10-6 0.005
(1000) NA 0.0004
(100) NA 0.006
200 NA 0.02
5.0 7.01 It 10-7 NA
150 NA 0.0001
2.0 1.34 It 10" NA
5.8 It «)", 0.36
50
50
CURRENT MAX
MCL
MCL
EPA WQC
CURRENT MAX
CA MCL
CA MCL
CURRENT MAX
CURRENT MAX
CURRENT MAX
CURRENT MAX
CURRENT MAX
. CURRENT MAX
MCL
CURRENT MAX
CA MCL
Page 42 of 52
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6.
Implementability.
7.
State acceptance/Support Agency acceptance.
8.
Community acceptance.
9.
Cost.
9.2
ANALYSIS OF ALTERNATIVES
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Alternatives 2, 3 and 4 basically provide equal protection of human health and the
environment because they all extract ground water that contains contaminants at
concentrations above drinking water standards. Extraction prevents further migration
of the plume. Deed restrictions protect against use of the aquifers before cleanup is
completed. After cleanup using Alternatives 2, 3 and 4, the predicted carcinogenic
risk without 1, 1-DCE would be 6 x 10-6 for the maximum plausible case. This is a
reduction of over 95 % from the projected carcinogenic risk whether arsenic and 1,1-
DCE are considered as carcinogens or arsenic is deleted and 1, 1-DCE is evaluated as
noncarcinogen with a modified reference dose. Water discharged following treatment
would meet NPDES requirements which are protective of human health and the
environment.
Alternative 3 and 4 could be considered slightly more protective than Alternative 2
since they would not involve the transfer of groundwater contaminants to the air.
Alternatives 2 and 3 both involve the destruction of some contaminants by
regeneration of the granular activated carbon. Alternative 4 would result in the
destruction of most contaminants as part of the treatment process. Air emissions from
Alternative 2 are considered sufficiently protective, however, since they fall within the
EPA acceptable cancer risk range at 1 X 10-5 and meet BAAQMD permit requirements.
Alternative 1 is less protective than Alternatives 2, 3 and 4 because it would allow
the contaminated ground water to continue migrating. Deed restrictions and well
permit restrictions would need to be imposed for a significantly greater amount of time
than those of Alternatives 2, 3 and 4, since natural attenuation of groundwater
contaminant concentrations would require an undetermined amount of time probably
greater than 100 years as compared to the approximately 12 year cleanup time for
Alternatives 2, 3 and 4.
Alternative 1 provides no reduction in risk. While future use of the contaminated
ground water may be unlikely, a future user of the contaminated ground water would
be exposed to a cancer risk of 1.25 X 10-3 and an HI of 5. Alternative 1 is least
protective of human health and the environment. Because it does not include deed
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. .
restrictions, Alternative 1 greatly increases the chances that an individual will install
a well into a migrating plume. ' .
COMPLIANCE WITH ARARS
Alternatives 2, 3 and 4 would attain all pertinent ARARS identified in Section 7. The
Safe Drinking Water Act MCLs and California Department of Health Services DW ALs
would be achieved by extracting ground water contamina,ted above these levels.
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
Alternatives 2, 3 or 4 because the groundwater extraction system would prevent the
plume from reaching surface waters or wet lands and the treatment system would
ensure that discharged water was protective of human health and the environment.
The RCRA land disposal restrictions would apply to the spent carbon from Alternatives
2 and 3 and would additionally apply to Alternative 2 in the event that it became
necessary to implement air stripper emissions control involving gas-phase activated
carbon. The spent carbon would be treated before reuse or disposal by an incineration.
process. .. .'
. .
Only Alternative 2 would need to comply with OSWER Directive 9355.0~28 and
BAAQMD Regulation 8, Rule 47 because of the air ~tripper emissions. These ARARs
are addressed by the BAAQMD permitting process. If air stripper operational
modifications become necessary, emissions' would be captured and destroyed by
available technology. .
The drinking water ARARS would not be attained by Alternative 1 since
contamination would be left in place. The Fish and Wildlife Coordination Act would
become an ARAR if the plume migrated to Calabazas Creek and other tributary
streams and marshes. California's resolution 68-16 would not be achieved since the
groundwater contaminants would unreasonaQly affect the present and potential uses
of the upper aquifers. . RCRA land disposal restrictions, NPDES requirements,
BAAQMD Regulation 8, and OSWER Directive .9355.0-28 would not apply to
Alternative 1 since no treatment is included.
REDUCTION OF TOXICITY. MOBILITY. OR VOLUME THROUGH TREA TME~T
Alternatives 2, 3 and 4 reduce the toxicity, mobility, and volume of groundwater
contaminants by removing greater than 99% of the contaminants from the extracted
ground water. Alternative 2 transfers part of the contaminants to ambient air where
their toxicity, mobility, ,and volume as air contaminants actually increases. In addition,
some of the VOCs are ozone precursors. The current air stripper is operating under
a BAAOMD permit that does not require emissions control. The remaining
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contaminants are concentrated onto granular activated carbon, which would then be
regenerated or properly disposed at a landfill. Contaminants would potentially be
destroyed during carbon regeneration, making any future release of the removed
contaminants impossible. The levels of contaminants that remain in the treated water
will be regulated by an NPDES permit.
Alternative 3 would concentrate up to 99% of the contaminants onto granular
activated carbon, which would then be regenerated or properly disposed at a landfill.
Contaminants would potentially be destroyed during carbon regeneration, making any
future release of the removed contaminants impossible. Contaminants that remain in
the treated groundwater would be discharged to surface water under the regulations
of an NPDES permit.
Alternative 4 would mix oxidizing chemicals with contaminated groundwater prior to
exposure to ultraviolet light sources. This process results in the breakdown of many
halogenated chemicals with rates of reduction that vary by chemical species. The rate
of destruction has varied from 90 to 99% for the halogenated solvents that are the
primary chemicals of concern at the AMD 915 facility. A pilot test of this technology
was completed at a neighboring facility with similar chemicals. The rates of
destruction were highly variable and some chemicals required multiple treatments to
achieve standards. The air effluent would be treated by a catalytic convertor and
regulated by BAAQMD regulations. If successful the technology would result in the
immediate destruction of 90 to 99% of the contaminants. Contaminants that remain
in the treated groundwater would be discharged to surface water under the
regulations of an NPDES permit.
Alternative 1 would not result in any reduction of toxicity, mobility, or volume.
LONG-TERM EFFECTIVENESS AND PERMANENCE
Alternatives 2, 3, and 4 include groundwater extraction which is intended to reduce
the level of contamination in the A and B Aquifer Zones to the cleanup standards
indicated in Section 8.2. Thus, potential risks to the community currently posed by
the site in its present condition are minimized. To ensure that the magnitude of
residual risks are minimized, the performance of the groundwater extraction system
will be carefully monitored on a regular basis and adjusted as warranted by the
performance data collected during operation.
The potential future risk from long-term exposure to volatilized contaminants that are
emitted from the soil and accumulate inside residences is addressed by the
groundwater extraction system in Alternatives 2, 3, and 4. Groundwater extraction
reduces the amounts of contaminants that could volatilize into the soil gas and even-
tually into surface air. Furthermore, deed restrictions will prevent the use of the most
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Alternative 4 may have some technical limitations. Several pilot scale studies of
UV loxidation technology ha,ve been completed in Santa Clara County with varied
results. The initial study at Lorentz Barrel and Drum indicated that a similar technology
was not successful in destroying over 90% of the chemicals of concern especially
some. halogenated solvents. A similar result was also noted from a pilot scale test
completed at the TRW Microwave facility. An additional study was completed at the
Lorentz Barrel and Drum site with more promising results. This may be indicative that
as this innovative technology matures results will improve, however the reliable
destruction of highly halogenated compounds is questionable.
There are no technical concerns regarding the implementability of Alternative 1.
Institutional controls required in Alternatives 2, 3, and 4 are administratively feasible.
COST'
All costs estimates are based on present calculations. The time for operation is
assumed to be 30 years for the no action alternative and the length of time estimated
to achieve cleanup for the active alternatives. The cost for Alternative 1 is $1.5
mill,ion. This cost is the result of ongoing monitoring. .
The present net worth cost for Alternative 2 is estimated to be $2.1 million.
Since the system is in place as an interim remedial action no additional capital costs
are included in this estimate. Extraction system operation and treatment testing and
evaluation m~ke up approximately 58% of this cost with the remaining 42% as a
result of groundwater monitoring. The estimated time to achieve background levels
of chemicals is 18 years at an estimated present net worth cost $2.8 million.
The present net worth cost of for Alternative 3 is estimated to be $5.1 million. It is
estimated that this alternative could reach MCLs in 12 years. The estimates to achieve
background levels of chemicals is 18 years at an estimated present net worth cost-
$6.7 million. The additional capital cost for this alternative has a present worth 01
,- $0.08 million. The majority of the increased cost as compared to Alternative 2 is the
cost of carbon replacement/regeneration.
The present net worth cost of Alternative 4 is estimated to be $4.0 million. It is
estimated that this alternative could reach MCLs in 12 years. The estimates to achieve
background levels of chemicals is 18 years at an estimated present net worth cost
$5.1 million. The additional capital cost for this alternative has a present worth of
. $0.6 million. The major cost factor for this alternative is increased operation cost. The
increased operation cost is the result of increased operator time and cost and the large
increase in electrical power consumption.
Page 47 of 52
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most contaminated groundwater prohibiting well drilling into any of the aquifers below
the site. Due to current zoning, there are no residences above or in close proximity
to the overall plume. Consideration should be given to re-evaluating the risk to
residents from the exposures specified above in the future. If necessary, based on
future evaluation, fans or other ventilation aids could be provided to any affected
buildings, and other precautions would be taken to protect potential future residents.
Treatment by air stripping provided by Alternative 2 is reliable for the long-term
removal of vacs from the ground water. Treatment residuals are expected to be
negligible based on the high volatility of the compounds present in the ground water.
Treatment by aqueous phase granular activated carbon provided by Alternatives 2 and
3 is reliable for the removal of vacs from the ground water. Treatment residuals are
expected to be negligible since they will be concentrated on a relatively small amount
of carbon that will either be properly disposed in a landfill or regenerated by a
destructive technology.
Alternative 1 provides no long-term effectiveness.
SHORT-TERM EFFECTIVENESS
The short-term impact to the health of workers and the community will be very
minimal for Alternatives 2, 3, and 4 because the groundwater extraction system is
already in place as the interim remedial action at the site. There would be no current
additional risks since the plume is already contained and the treatments are protective.
Groundwater cleanup time is estimated to require about 12 years. Uncontrolled air
emissions from Alternative 2 make it slightly less effective in protecting health and the
environment than Alternatives 3 and 4 in the short-term.
Alternative 1 does not include the implementation of treatment remedies; therefore,
there are no additional risks to the community. Risks associated with the contaminar.t
plume would remain at the site for over 100 years until natural attenuation reduces
the contaminant concentrations down to the cleanup standards.
IMPLEMENTABILITY
Alternatives 2, 3, and 4 include the same extraction system which is already in place.
B..ith alternatives provide groundwater treatment with either an air stripper or carbon
adsorption. Both methods are proven technologies, however due to the large
treatment volumes at the AMD 915 facility it is unclear that the size or number of
carbon vessels required is not a technical problem due to onsite space limitations. In
addition, both alternatives are administratively feasible using existing permits for
discharge or air emissions.
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SUPPORT AGENCY ACCEPTANCE
The Feasibility Study and the Proposed Plan Fact Sheet were reviewed by the RWOCB
and they concur with EPA's preferred alternative.
COMMUNITY ACCEPTANCE.
The Proposed Plan was presented to the community of Sunnyvale in a public meeting
on March 27, 1991 and in a fact sheet. A single technical comment was received
regarding the efficacy of groundwater extraction under the current drought conditions.
The drought condition is considered to be a temporary condition that will not effect
the long term operation of the groundwater extraction system. Other comments
received are addressed in the Responsiveness Summary (Appendix A).
9.3
THE SELECTED REMEDY
.. .
9.3.1 Basis of Selection
Maintaining the existing groundwater extraction system with the existing treatment
system of an air stripper followed by carbon adsorbtion (Alternative 2) is the selected
remedy for the AMD 915 Superfund site. This remedy addresses only the
contaminated ground water since all contaminated soils and structures were removed
during the interim remedial a~tion.
Alternatives 2, 3, and 4 were the only alternatives that met all of the nine criteria and
adequately ad(lressed the remedial action objectives. The only difference between the
three alternatives is the type of treatment. Air stripping and carbon adsorption are
equally effective at treating the groundwater contaminants, and only differ in the area
of treatment residuals. Under a current BAAOMD permit, residual contaminants from
the air stripper are discharged directly to the air. Residual contaminants adsorbed to
the liquid-phase granular activated carbon would be destroyed during regeneration as
treatment prior to confinement as a small concentrated volume in a proper landfill.
I
Despite slight advantages of carbon adsorption and UV/H202 oxidation in dealing with
treatment residuals resulting in better reduction of toxicity, mobilitY, and volume, the
existing treatment system provides several advantages. These advantages include the
fact that the air stripper with carbon polish costs two to four times less than either
carbon adsorption or UV/H202 oxidation and the existing system and carbon
adsorption are both proven technologies, however it is uncertain that carbon
adsoi'btion with the high flow volumes at AMD 915 would be reliable or practical
since it would require very large treatment units or frequent carbon regeneration. The
air stripper and small carbon polish unit are already inst~lIed and operating in
accordance with current permits. In addition, residuals from the 'air stripper could
potentially be captured and destroyed by available emissions control technology if
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. .
permit modifications become necessary. Therefore, Alternative 2. was selected as the
groundwater remedy for AMD 915. .
9.3.2 Features of the Remedy
I
Alternative 2 maintains the existing groundwater extraction systerrt with the existing
air stripper for a present worth cost of 1.5 million dollars. It is already implemented
and operating with acceptance from the community and federal~ state, and local
agencies. Alternative 2 consists of the following features: I
I
Groundwater extraction from eight on-site wells, four A Aquifer wells
281 aquifer wells and 2 82 aquifer wells. These wells' send a combined
flow of approximately 50 gpm to the air stripper. The well locations and
pumping rate contain the plume and prevent further migration of VOC-
contaminated ground water. The theoretical cancer risk of 2 x 10.3 for
a future use of drinking water contaminated with vinyl chloride, 1,1
DCA, PCE, and TCE will be continually reduced over an estimated 12
year period to a risk for a 70 year lifetime exposure of 6.7 x 1008. Thus,
groundwater extraction until drinking water standards are achieved will
attain ARARs and permanently restore the contaminated aquifers to their
maximum beneficial uses. I
.
.
Air stripping will remove more than 99% of the VOCs from the extracted
ground water allowing the treated effluent to be discharged under an
existing NPDES permit to a storm tributary to Calabazas Creek without
degrading this surface water or presenting a significant risk to human
health and the environment. The stripped VOCs are emitted directly to
the air under an existing 8AAOMD permit. The air stripper will include
air emissions control if emissions exceed levels permitted by the
8AAOMD. .
.
Periodic groundwater monitoring will verify plume containment,
determine current plume boundaries, and follow the decrease in VOC
concentrations as the cleanup progresses.
.
Institutional controls in the form of a deed restriction filed by the
discharger will be required to limit access to site groundwater until the
cleanup standards have been met. I
I
!
Reuse of 100% of the treated effluent is the reqJired goal for the
extraction and treatment system. . !
9.3.3 Uncertainty in the Remedy
.
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'j
I
!
, ,
, The goal of this remedial action is to restore groundwater to its beneficial uses, which
at this site include 8 potential source of drinking water. Based on information
obtained during the RI and on 8 careful analysis of all remedial alternatives, EPA and
the RWaCS believe that the selected remedy will achieve this goal. It may become
apparent, during implementation or operation of the system and its modifications, that
contaminant levels have ceased to decline and are remaining constant at levels higher
than the cleanup standards over some portion of the plume. In such a case, the
system performance standards and/or the remedy may be reevaluated by EPA.
. " '1
The selected remedy will include groundwater extraction for an estimated period of
12 years at AMD 915, during which the system performance l will be carefully
monitored on a regular basi~ and adjusted as warranted by the performance data
coll~cted during operation. Modifications may include any or all o~ the following:
i
at individual wells where cleanup standards have been ~ttained, pumping
may be discontinued; 'I
I
I '
alternating pumping at wells to eliminate stagnation points;
, , , ' I
pulse pumping to allow aquifer equilibration and ~ allow adsorbed
contaminants to partition into groundwater; and I
installation of additional extraction wells to facilitate or accelerate
cleanup of the contaminant plume.
a)
b)
'c)
d)
,
I
To ensure that cleanup standards continue to be. maintained, the aquifer will be
monitored at those wells where pumping has ceased on an occurrence of every five
years following discontinuation of groundwater extraction. .
10.0 STATUTORY DETERMINATIONS
, I
The selected remedy protects human health and the environme'nt through extraction
and treatment of VOC-contaminated groundwater. The selected remedy will comply
with Section 121 of CERCLA. This remedy addresses only the contaminated
groundwater since all contaminated soil and structures were removed during the
interim remedial actions. The reductions in risk are summarized: for groundwater
extraction and treatment in Section 9.3.2 of this ROD. There are no long-term or
short-term threats' associated with the sele'cted remedy that cannot be readily
controlled. In addition, no adverse cross-media affects are expected trom the remedy.
The selected remedy will' comply with all of the identified che,J,ical, action, and
location specific ARARs that are described in Section 7 of this ROD: In the event that
it becomes apparent that the drinking water ARARs may not be achievable as
described in Section 9.3.3.of this ROD, the system performance standards and/or the
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remedy may be reevaluated.
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The present worth cost of the selected remedy is $2.1 million. It is the least costly
of three alternatives that provide equal protection of humanl health and the
environment. The selected remedy is already installed and operating in accordance
with current permit requirements for discharge of treated groundwater and for air
emissions. I
I
The selected remedy uses permanent solutions and alternative treatment (or resource
recovery) technologies 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. Section 9.3.2 of this ROD summarizes the key features
of the selected remedy. The remaining toxicity, mobility, and volume of contaminants
emitted from the air stripper could potentially be captured and destroyed by available
emissions control technology if permit modifications become necessary.
,
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.
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
There were no significant changes between the preferred alternative and this Record
of Decision.
PART III. RESPONSIVENESS SUMMARY
I
I
This responsiveness summary reviews comments and questions regarding the
Remedial Investigation/Feasibility Study (RI/FS) and Proposed Final Cleanup Plan
(proposed plan) for Advanced Micro Devices facilities at 901/902' Thompson Place
(AMD 901/902) 800 915 DeGuigne Drive (AMD 915), the former TRW Microwave at
825 Stewart Drive (TRW) the Signetics facility at 811 E. Arques, all in Sunnyvale. A
single responsiveness summary was prepared for this group o~ Superfund sites
because actions at all sites potentially impact the same local community. The study
area that encompasses AMD 901/902, Signetics, and TRW has been divided into four
area-specific operable units. Separate proposed plans have been developed for each
1.0 INTRODUCTION
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of these four operable units and for AMD 915.
This summary includes comments received during the 60 day period from the opening
of public comment at the Board meeting of March 20, 1991 through the close of
public comment on May 20, 1991. All comments during this period were received by
the RWQCB. Additional opportunity for comment was given to the public at the
RWQCB meeting on June 19, 1991. This Record of Decision does not include any
significant changes to the proposed plan presented at the community meeting of
March 27, 1991 and does not differ significantly from the plan adopted by the
RWQCB.
2.0 REGIONAL WATER QUALITY CONTROL BOARD RESPONSES
i
Since RWQCB is the lead agency for AMD 915 and received all comments, RWQCB
prepared the Responsiveness Summary (Attachment A). EPA, as the support agency,
has reviewed and concurs with the RWQCB responses.
Written comments were received from Santa Clara Valley Water District (SCVWD);
Supervisor Ron Gonzales, Santa Clara County Board of Supervisors; Santa Clara
County Office of Education; Silicon Valley Toxics Coalition (SVTC); San Miguel
Homeowners Association; California Department of Health Services, Environmental
Epidemiology and Toxicology Branch (EETB); and two community members, Gary
Holton and John Schwartz. Specific comments received at the community meeting
held at the Westinghouse Auditorium in Sunnyvale, March 28, 1991, general
comments from an informal meeting held May 7, 1991 at the San Miguel School site
in Sunnyvale and verbal comments received by telephone during the comment period
and two meetings with the San Miguel Homeowners Association, May 23 and May
30, 1991, will also be outlined and addressed separately. The comments by SCVWD
and Gary Holton were supportive of the proposed plan, as outlined above, and as such
will not require a specific response.
The attached Responsiveness Summary is divided into two parts; Part I provides a
summary of the major issues raised by commentors and focuses on the concerns of
the local community; Part II is a more technical response to all significant comments.
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