Superfund Record of Decision: Advanced Micro Devices 901 (Signetics) (TRW Microwave), CA


United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R09-91/073
September 1991
Superfund
Record of Decision:
Advanced Micro Devices 901
(Signetics) (TRW Microwave), CA

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50272-101
REPORT DOCUMENTATION 1. REPORT NO. 2.
PAGE EPA/ROD/R09-91/073
4. THe and Subtitle
SUPERFUND RECORD OF DECISION .
Advanced Micro Devices 901 (Signetics) (TRW Microwave) , CA
First Remedial Action - Final
7. Author(s) .
8. Performing Organization Name end Address
12. Sponsoring Organization Name and Address .
, U.S. Environmental Protection .Agency i
401 M Street, S.W.
Washington, D.C. 20460
3. Recipient's Accession No.
5. Report Date
09/11/91
6.
8. Performing Organization Rept No.
10. Proiect/Task/Work UnH No.
11. Contract(C) or Gr«nt(G) No.
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EPA/ROD/RO9-91/073
Advanced Micro Devices 901 (Signetics)(TRW Microwave), CA
First Remedial Action - Final

Abstract (Continued)

underground waste solvent storage tank at the Signetics site and responses to an
information questionnaire regarding an underground tanks investigation at the TRW site
resulted in a number of investigations that revealed extensive contamination of soil and
ground water. Several initial remedial measures were conducted at the AMD OU. During
1983 and 1984, acid neutralization sumps and approximately 217 cubic yards of
contaminated soil were removed. From 1984 to 1988, remediation of ground water was
implemented using extraction wells and dewatering sumps. Several initial remedial
measures also were conducted at the Signetics OU. From 1982 to present, ground water has
been pumped from various site locations and treated using air stripping and carbon
adsorption, followed by air stripping to control off-gases and reuse of the treated water
in industrial processes. Contaminated soil has been removed from three separate
locations, including 4,720 cubic yards of soil from a waste solvent storage tank area in
1983. In 1989, three vapor extraction wells were installed to treat contaminated soil.
Several initial remedial measures also have been conducted at the TRW OU. From 1983 to
1984, an underground waste solvent storage tank and 120 cubic yards of onsite
contaminated soil were removed. From 1984 to present, ground water has been pumped and
treated using air stripping, followed by onsite discharge to surface water. In addition,
two ground water extraction systems pump contaminated ground water from the 100-acre
offsite plume. The extracted water is treated at a neighboring AMD facility using air
stripping, followed by liquid phase granular activated carbon polisher and onsite
discharge to surface water, or reuse by the facility. This Record of Decision (ROD)
collectively addresses final remediation of soil and ground water in the four separate
OUs within the study area. The primary contaminants of concern affecting the soil and
ground water are VOCs including PCE and TCE; and other organics.

The selected remedial action for this site includes separate remedies for the four
different OUs of the study area. The remedy for the AMD OU includes excavating 37 cubic
yards of onsite contaminated soil, followed by offsite incineration and/or disposal, and
backfilling the excavation with clean soil; and continuing onsite pumping and treatment
of ground water using air stripping and carbon adsorption of off-gases, followed by reuse
of the treated water. The remedy for the Signetics OU includes expanding the onsite soil
vapor extraction system and continuing onsite pumping and treatment of ground water using.
air stripping, followed by aqueous-phase carbon polishing, reuse of the treated water,
and vapor-phase carbon treatment of the effluent air stream. The remedy for the TRW OU
includes continuing onsite pumping and treatment of ground water using air stripping,
followed by onsite discharge of treated water to surface water. The remedy for the
offsite ground water OU includes continuing and expanding the pumping and treatment
system for contaminated ground water using air stripping and aqueous-phase carbon
adsorption, followed by reuse of the treated water or onsite discharge to surface water,
and offsite regeneration of spent carbon. Each OU also will involve continuing ground
water monitoring, and implementing institutional controls including deed and ground water
use restrictions. The estimated present worth cost for the remedial action for all OUs
is $11,900,000, which includes an estimated O&M cost of $225,000 for the AMD OU; $236,000
for the Signetics OU; and $255,000 for the offsite ground water OU. No annual O&M cost
was provided for the TRW OU.

PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil clean-up goals have been set at
background or total VOCs 1 mg/kg based on State policy. Chemical-specific ground water
clean-up goals are based on State and Federal MCLs, and include PCE 5 ug/1 (State) and
TCE 5 ug/1 (State).
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RECORD OP DECISION
ADVANCED MICRO DEVICES #901/902
SIGNETIC8
TRW MICROWAVE

COMBINED SUPERFUND SITES

SUNNYVALE, CALIFORNIA
September 11, 1991

U.S. ENVIRONMENTAL PROTECTION AGENCY

REGION 9
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TABLE OF CONTENTS

PART I. DECLARATION 1
1.0 SITE NAMES AND LOCATIONS 1
2.0 STATEMENT OF BASIS AND PURPOSE 1
3.0 ASSESSMENT OF THE SITE 1
4.0 DESCRIPTION OF THE REMEDY 1
5.0 DECLARATION 3

PART II. DECISION SUMMARY 4
1.0 SITE NAME, LOCATION, AND DESCRIPTION ........ 4
1.1 SITE NAME AND LOCATION 4
.1.1.1 AMD 901/902 Operable Unit 4
1.1.2 Signetics Operable Unit 8
1.1.3 TRW Microwave Operable Unit 8
1.1.4 Off site Operable Unit 11
1.2 REGIONAL TOPOGRAPHY 11
1.3 ADJACENT LAND USE 11
1.5 HYDROGEOLOGY 13
1.6 WATER USE 15
1.7 SURFACE AND SUBSURFACE STRUCTURES 16
1.7.1 AMD Operable Unit 17
1.7.2 Signetics Operable Unit 17
1.7.3 TRW Operable Unit 20
1.7.4 Off site Operable Unit 20
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 20
2.1 HISTORY OF SITE ACTIVITIES 22
2.1.1 AMD Operable Unit 22
2.1.2 Signetics Operable Unit 22
2.1.3 TRW Operable Unit 23
2.2 HISTORY OF SITE INVESTIGATIONS 24
2.2.1 AMD Operable Unit 24
2.2.2 Signetics Operable Unit 25
2.2.3 TRW Operable Unit 25
2.3 HISTORY OF ENFORCEMENT ACTIONS 26
2.3.1 AMD Operable Unit 26
2.3.2 Signetics Operable Unit 27
2.3.3 TRW Operable Unit 27
3.0 COMMUNITY RELATIONS 28
3.1 Community Involvement 28
3.2 Fact Sheets 28
4.0 SCOPE AND ROLE OF THE RESPONSE ACTION 29
4.1 SCOPE OF THE RESPONSE ACTION 29
4.1.1 AMD Operable Unit 29
4.1.1.1 AMD Interim Remedial Measure ... 29
4.1.1.2 AMD Selected Remedy 31
4.1.2 Signetics Operable Unit 31
4.1.2.1 Signetics Interim Remedial Measure 31
4.1.2.2 Signetics Selected Remedy .... 32
4.1.3 TRW Operable Unit 34
4.1.3.1 TRW Interim Remedial Measure ... 34
4.1.3.2 TRW Selected Remedy 35
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4.1.4 Off site Operable Unit .. 38
4.1.4.1 Offsite Interim Remedial Measure . 38
4.1.4.2 Offsite Selected Remedy 38
4.2 ROLE OF THE RESPONSE ACTION 41
5.0 SUMMARY OF SITE CHARACTERISTICS 41
5.1 SOURCES OF CONTAMINATION 41
5.1.1 AMD Source Investigation 41
5.1.2 Signetics Source Investigation 42
• 5.1.3 TRW Source Investigation 42
5.2 DESCRIPTION OF CONTAMINATION 43
5.2.1 SOIL INVESTIGATIONS . . 43
5.2.1.1 AMD Operable Unit ...;.... 43
5.2.1.2 Signetics Operable Unit 43
5.2.1.3 TRW Operable Unit 44
5.2.2 GROUNDWATER INVESTIGATIONS 45
5.2.2.1 AMD Operable Unit 45
5.2.2.2 Signetics Operable Unit 45
5.2.2.3 TRW Operable Unit 46
5.2.2.4 Offsite Operable Unit 46
5.2.3 AIR INVESTIGATIONS 47
5.2.3.1 AMD 901/902 Operable Unit .... 47
5.2.3.2 Signetics Operable Unit 48
5.2.3.3 TRW Operable Unit 49
5.2.3.4 Offsite Operable Unit 49
6.0 SUMMARY OF SITE RISKS 52
6.1 TOXICITY ASSESSMENT 52
6.2 RISK CHARACTERIZATION 55
6.2.1 Soil 56
6.2.1.1 AMD 901/902 Soil 56
6.2.1.2 Signetics Soil 56
6.2.1.3 TRW Soil 56
6.2.1.4 Off site Soil 57
6.2.2 Air 57
6.2.2.1 AMD 901/902 57
6.3.2.2 Signetics 58
6.3.2.3 TRW 59
6.3.2.4 Offsite 59
6.3.3 Groundwater 60
6.3 PRESENCE OF SENSITIVE HUMAN POPULATIONS .... 62
6.4 PRESENCE OF SENSITIVE ECOLOGICAL SYSTEMS .... 62
6.5 CONCLUSION 63
7.0 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
(ARAR8) 63
7.1 TYPES OF ARARS 64
7.2 CONTAMINANT-SPECIFIC ARARS AND TBCS 64
7.3 ACTION SPECIFIC ARARS AND TBCS 65
7.4 LOCATION-SPECIFIC ARARS 67
8.0 DESCRIPTION OF ALTERNATIVES 67
8.1 REMEDIAL ACTION OBJECTIVES . 67
8.2 CLEANUP STANDARDS 68
8.2.1 Cleanup Standards 68
8.2.2 Compliance Boundaries 70
8.3 REMEDIAL ACTION ALTERNATIVES 75
8.3.1 AMD Operable Unit 75
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8.3.2 Signetics Operable Unit 77
8.3.3 TRW Operable Unit 78
8.3.4 Off site Operable Unit 79
9.0 COMPARATIVE ANALYSIS OF ALTERNATIVES 80
9.1 NINE CRITERIA 80
9.2 ANALYSIS OF ALTERNATIVES 81
9.2.1 AMD Operable Unit 82
9.2.1.1 AMD Soils 82
9.2.1.2 AMD Groundwater 87
9.2.2 Signetics Operable Unit 90
9.2.3 TRW Operable Unit . 94
9.2.4 Off site Operable Unit 98
9.3 THE SELECTED REMEDY 102
9.3.1 Basis of Selection 102
9.3.2 Features of the Remedies 103
9.3.3 Uncertainty in the Remedy 105
10.0 STATUTORY DETERMINATIONS 106
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 107
4
PART III. RESPONSIVENESS SUMMARY 107
1.0 INTRODUCTION 107
2.0 REGIONAL WATER QUALITY CONTROL BOARD RESPONSES . . . 107
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LIST OF FIGURES

Figure 1 - Location Map 5
Figure 2 - Operable Unit Nap 6
Figure 3 - AMD 901/902 Site Map 7
Figure 4 - Signetics Site Map 9
Figure 5 - TRW Site Map 10
Figure 6 - Offsite TCE Plume Map 12
Figure 7 - Schematic Hydrogeologic Log 14
Figure 8 - Historical Waste Storage Locations, AMD 901/902 . . 18
Figure 9 - Waste Storage, Signetics, 811 E. Argues . ' 19
Figure 10 - Chemical Storage and Processing, TRW, 825 Stewart
Dr 21
Figure 11 - AMD 901/902 Groundwater Extraction System 30
Figure 12 - Signetics Groundwater Extraction System 33
Figure 13 - TRW Groundwater Extraction System 36
Figure 14 - Offsite Groundwater Extraction System 39
Figure 15 - Soil Flux Sample Location Map 51
Figure 16 - A Zone Plume Boundaries 73
Figure 17 - B Zone Plume Boundaries 74

LIST OF TABLES

TABLE 1 - NPDES DISCHARGE LIMITS, SIGNETICS 34
TABLE 2 - NPDES DISCHARGE LIMITS, TRW 37
TABLE 3 - NPDES DISCHARGE LIMITS, OFFSITE 40
TABLE 4 - AMD 901, SIGNETICS, TRW DATA SUMMARY 53
TABLE 5 - ADULT CARCINOGENIC RISK, AMD 901/902, SIGNETICS, AND TRW
.....' . 61
TABLE 6 - CLEANUP STANDARDS FOR THE CHEMICALS OF CONCERN IN
GROUNDWATER 69
TABLE 7 - HAZARD INDEX AT CLEANUP STANDARDS, AMD 901/902,
Signetics, TRW 71
TABLE 8 - CANCER RISK AT CLEANUP STANDARDS 72
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PART I. DECLARATION

1.0 SITE NAMES AND LOCATIONS

Advanced Micro Devices
901/902 Thompson Place
Sunnyvale, CA 94088

Signetics, Inc.
811 East Argues Avenue
Sunnyvale, CA 94088

TRW (FEI) Microwave
825 Stewart 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 901/902, Signetics and TRW
Microwave Superfund sites in Sunnyvale, California. This group of
sites has been divided into four operable units (OUs). 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 indices (Attachment B)
identify the documents upon which the selection of the remedial
actions are based. The State of California concurs with the
selected remedies.
3.0 ASSESSMENT OF THE SITE

Actual or threatened release of hazardous substances from these
sites, if not addressed by implementing the response actions
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.

4.0 DESCRIPTION OF THE REMEDY

Remedies have been selected for each operable unit. The remedy for
the AMD 901/902 operable unit consists of soil excavation followed
by offsite incineration/disposal, continued groundwater extraction
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followed by treatment of the extracted groundwater with the
existing air stripper, and reuse of the treated water. The air
stripper includes air emissions control and is regulated by the Bay
Area Air Quality Management District (BAAQMD). Additional
contaminated soils and structures were removed as part of interim
remedial actions.

The remedy for the Signetics operable unit consists of vapor
extraction. for soil remediation with continued groundwater
extraction, treatment of contaminated water with the existing air
stripper and reuse of the treated water. The groundwater treatment
system uses multiple air strippers. The initial -air stripper
includes air emissions control and the second set of air strippers
are not controlled. All air strippers meet the requirements of the
BAAQMD regulations. Aqueous phase carbon is utilized as a final
treatment and serves as a backup system to the air stripping
systems. Additional contaminated soils and structures were removed
as part of interim remedial actions.

The remedy for the TRW operable unit consists of continued
groundwater extraction, treatment of contaminated water with the
existing air stripper and discharge of the treated groundwater to
surface water under an NPDES permit. The required goal for water
reuse is 100%. The groundwater treatment system uses an air
stripper to remove chemicals from the groundwater. The air effluent
from the air stripper is not controlled. The air stripper meets the
requirements of the BAAQMD regulations and air emission control
will be added to the system if required by BAAQMD.

The remedy for the offsite operable unit consists of continued
groundwater extraction. The contaminated groundwater is piped to
the AMD facility at 915 DeGuigne Drive for treatment by an air
stripper, followed by reuse or discharge of the treated groundwater
to surface water under an NPDES permit. The required goal for water
reuse is 100%. The groundwater treatment system uses an air
stripper to remove chemicals from the groundwater. The air effluent
from the air stripper is not controlled. The air stripper meets the
requirements of the BAAQMD regulations and air emission control
will be added to the system if required by BAAQMD. Additional
contaminated soils and structures were removed as part of interim
remedial actions.

These remedial actions address the principal risks remaining within
a study area defined by four operable units including the area from
approximately Arques Avenue on the south and north to Lake Haven
Drive and bounded on the east by DeGuigne Avenue and Fair Oaks
Avenue on the West. These risks are addressed 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 potential
future water supplies.

Page 2 of 108
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5.0 DECLARATION

The selected remedies are protective of human health and the en-
vironment, comply with federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and are cost-effective. These remedies utilize permanent
solutions and alternative treatment (or resource recovery) tech-
nologies to the maximum extent practicable and satisfy the
statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element.

Because the remedies will result in hazardous substances remaining
on-site above health-based levels, a five-year review, pursuant to
CERCLA Section 121, 42 U.S.C. Section 9621, will be conducted at
least once every five years after initiation of the remedial action
to ensure that the remedy continues to provide adequate protection
of human health and the environment.
UU vx_ ^-ll'
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PART II. DECISION SUMMARY

This Decision Summary provides an overview of the problems posed by
the Advanced Micro Devices, Signetics, TRW Microwave Superfund
sites and an "offsite" area where groundwater contaminant plumes
have become commingled ("the Study Area"), the remedial
alternatives, and the analysis of the remedial alternatives. This
Decision Summary explains the rationale for remedies selected at
the three areas and how the selected remedies satisfy the statutory
requirements.

1.0 SITE NAME, LOCATION, AND DESCRIPTION

1.1 SITE NAME AND LOCATION

As referenced above this ROD includes three separate Superfund
sites and an offsite area located in Sunnyvale, Santa Clara County,
California (Figure 1). These areas have been combined into a large
study area (Figure 2). Each of the three Superfund sites and their
commingled plume have been considered separately as one of four
operable units (OUs) within the larger study area. A detailed
discussion of each operable unit is presented in the sections
below.

1.1.1 AMD 901/902 Operable Unit

The Advanced Micro Devices facility (Figure 3) located at 901/902
Thompson Place, Sunnyvale California (AMD 901/902) consists of two
low rise buildings connected by a common foyer and entrance. This
is located in an area of low to flat relief about 3 miles south of
the southern extension of the San Francisco Bay in an area broadly
bounded by the Bayshore, Central, and Lawrence Expressways and Fair
Oaks Avenue. This is an industrial park setting dominated by low
rise industrial buildings common in the electronics industry of
Santa Clara County. The industrial park area is dominated by
electronics manufacturers. Mixed commercial and light industrial
use is common immediately surrounding the industrial park area. No
residential property is in the immediate vicinity of the AMD
901/902 operable unit. Some residential property lies to the west
and south of the industrial park. The area to the north of the AMD
901/902 operable unit is part of the industrial park and includes
the TRW operable unit. Land use immediately north of the industrial
park area is mixed commercial property, followed by a predominately
residential area further north.
Page 4 of 108
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Figure 1. Location Map of the Study Area including:
AMD 901/902, Signetics, and TRW Microwave
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— Facility/OU boundaries
— Study Area perimeter
Figure 2. Map of Operable Units
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EXPLANATION
Point Source Location*
(NeutrofilolJon ond Storage Tank!
AMD WELLS
(ENGINEERING-SCIENCE)
• 1-S Tint Send Completion!
(A - Zon.)
(-0 S*cond Sand Comptalioni
(8 - Zant) (-00 ond -DOD an
d««p«f cond compt«tions)
SIGNmCS WELLS (EMCON)

* S-78A ShaOo« *«n (A - Zon«)

W.O (B - Zoo.)
TRW WELLS (WEISS ASSOC.)
T-2A Hnt Sand Completion.
(A - Zan.)
T-2C IMrd Sand Compl.Uon.
(C - Ion.)
Croundwotw Lew Contour
(USGS Datum. (Ml obov« MSL)
Doshttd «h«r* approximate)
I I I
D r—Inf
Figure 3. AMD 901/902 Site Map
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1.1.2 Signetics Operable Unit

Signetics owns and operates a facility located at 811 East Argues
Avenue, in Sunnyvale. This location is part of a larger complex of
facilities operated by Signetics, including 440 Wolfe and several
facilities along Stewart Drive (Figure 4). This is an area of
Santa Clara County developed as an industrial park, dominated by
low rise buildings. The major business activity of the area is
semiconductor manufacture and research and development. The
Signetics' facilities are representative of property development in
this area.

This is an area of low topographic relief in the southern portion
of the Santa Clara Valley. Surface drainage in the area is to the
north, toward San Francisco Bay. Vegetation is limited to grass
and shrubs. Residential development has occurred in the area south
of the Signetics facility within the last two years. The area
immediately west of the Signetics OU is park land. The area
immediately north of the Signetics OU is the former Sunnyvale High
School property, which is currently used as an electronics research
and development facility. This area includes a track and ball field
for recreational use by employees.

1.1.3 TRW Microwave Operable Unit

The former TRW Microwave facility (TRW) is located at 825 Stewart
Drive, Sunnyvale, Santa Clara County. Aerotech Industries and this
site were wholly acquired by TRW Microwave in 1974 and was operated
by TRW Microwave from July 1974 to August 1986. The property was
purchased by Tech Facility 1, Inc. in 1987. Some assets at this
site were acquired by FEI Microwave, Inc. in July 1987. The
manufacturing facility is currently operated by FEI Microwave, Inc.
This location is near the intersection of the Lawrence Expressway
and Route 101 (Figure 5). This is an area of the Santa Clara Valley
of low topographic relief. The drainage in the area is toward the
north to San Francisco Bay. The facility is located in an
industrial park setting dominated by low buildings separated by
paved parking lots, fields and streets, with some landscaping. The
dominant activity in this area is related to the semiconductor
industry, though. the industrial park is bordered by residential
property particularly to the north.
Page 8 of 108
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Figure 4. Signetics Site Map
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Figure 5. TRW Microwave Site Map
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1.1.4 Offsite Operable Unit

The study area for the offsite operable unit begins north of the
Signetics operable unit (Figure 2) and extends north of Duane
Avenue in an area bounded approximately by the Sunnyvale East
Drainage Channel on the west and Santa Paula Avenue on the east.
The study area extends north of Highway 101 to just north of
Lakehaven Drive. The actual offsite operable unit is loosely
defined as-the area inside the 5 pg/1 (Figure 6) isopleth for TCE
in groundwater. This covers an area of about 100 acres and includes
commercial and residential property. The area south of Duane Avenue
is industrial property and includes the former Sunnyvale High
School Buildings currently used as an industrial research and
development facility. Commercial and retail property is mixed with
multiple unit residential property along the north side of Duane
Avenue. The remainder of the offsite area is residential property,
including approximately 600 single family residential units and the
former San Miguel Elementary School. The Elementary School
currently is used as a daycare facility for the community and
houses a Headstart Program for Sunnyvale.

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 study area site is a broad area extending to just north of the
Bayshore Freeway, bounded on the south by the Central Expressway,
and bounded east to west by the Lawrence Expressway and Fair Oaks
Drive (see Figure 1). The facility is located in an industrial
park setting bordered by residential areas. The area to the east is
dominantly commercial and retail space. The area immediately to the
west of the study area is mostly residential property. The land to
the north of the study area is a mix of multiple and single family
residential property including several large trailer park
developments and retail centers.

Approximately 60% of the study area acreage is devoted to
industrial and commercial use. The former San Miguel School
facility accounts for about 5% of the study area with the remainder
used as residential property. The recreational facilities within
the surrounding areas include a park along Fairoaks which includes
ball fields and tennis courts.
Page 11 of 108
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Apri 1989 TCE Concentration, ppb

~ Decombart988TCE Cone em rai Ion. ppb

Chemical Isocoooentration Contours.
(tasheTwtweWeiTOd
Figure 6. Offsite TCE Plume Map
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1.4 HISTORICAL LAND USE

Land use in Santa Clara County, until the late 60 *s, was
agricultural, predominantly commercial fruit orchards. Development
of light industrial manufacturing facilities began in the late
50's. As the area developed a reputation as a center of the micro-
electronics industry, development accelerated through the 70's.
This, along, with increased demand for residential property related
to the increased industrialization, has limited agriculture to
isolated locations and the fringes of the Santa Clara Basin.

All of the industrial facilities within the study area were built
on land that had previously been used for agriculture and all were
designed and built as electronics manufacturing plants. While
manufacturing processes have varied among the facilities and
through time, the manufacturing processes at these sites have
involved the use of solvents, caustics, metals, and acids. The
current trend is a decline in the importance of manufacturing and
increased emphasis on research and development activities.

1.5 HYDROGEOLOGY

Stratigraphy in the valley surrounding the study area is
characterized by interbedded and interfingering sands, silts and
clays. These sediments were deposited in complex patterns by
fluvial-alluvial systems draining the uplands to the south with
sediments deposited as the streams flowed north toward the Bay.

The nomenclature applied to the water bearing units in the study
area is representative of the hydrogeology within the Santa Clara
Groundwater Basin. A number of shallow water bearing units are
separated from deeper aquifers by a thick persistent aguitard. 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 B zones (Figure 7). 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 B-C aguitard. The aquitard has been reported to
be between 50 and 100 feet thick in Santa Clara Valley.

Six local aquifers have been identified through the investigation
in the study area and the deeper, B-C aquitard (Figure 7) has been
confirmed at both the TRW and Signetics operable units. Regional
investigation has indicated that deeper aquifers do exist in the
Santa Clara Valley Groundwater Basin and are probably present in
the project area. The shallowest water bearing zone has been
designated the A zone and generally occurs from 6 to 25 feet below
the ground surface. This is the most persistent, permeable unit
near 825 Stewart Drive and generally contains from 1 to 19 feet of
permeable material. The next unit has been designated as the Bl
aquifer and generally occurs from 25 to 55 feet below ground

Page 13 of 108
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REGIONAL
TYPICAL
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Schematic Hydrogeologic Log
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surface and contains 0.5 to 15 feet of permeable materials. The
next unit has been designated as the B2 aquifer and occurs from 45
to 55 feet below the ground surface. It generally contains from 6
to 8 feet of permeable material. The next unit, the B3, is
relatively thin and only encountered in a few borings at the TRW
site. It consists of from 1 to 5 feet of permeable material. The
next unit, B4, begins from 82 to 86 feet below ground surface and
contains 1 to 4 feet of permeable material. The deepest unit
identified-at the TRW site is aquifer B5. This aquifer occurs from
116 to 123 feet below ground surface and contains 5 to 7 feet of
permeable material.

The static groundwater flow direction within the study area is to
the north-northeast in all aquifers. The vertical gradient has
been documented to be upward under normal conditions in the study
area. The flow direction and vertical hydraulic gradient may be
reversed locally in the vicinity of groundwater extraction wells
operating in the A, Bl, B2, and B3 aquifers.

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 B water bearing zones (see Section 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,
groundwater in this area was used as irrigation supply and for
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 as part of the Remedial
Investigation report, the RWQCB has determined that neither of
these two exceptions apply to the A and B zones in the study area.
Thus, the A and B zones are considered to be potential sources of
drinking water by RWQCB. EPA agrees with this determination.

AMD 901/902, TRW Microwave and Signetics were proposed for
inclusion on the National Priorities List (NPL) (see Section 2.3)
primarily because of the potential threat from past chemical

Page 15 of 108
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releases to the quality of this valuable resource. The major
concern at the site steins 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 study
area are perforated from 190 to 390 feet below ground surface.

Currently, - the nearest municipal drinking water supply well
downgradient of the study area is a Santa Clara Valley Water
District well, which is located more than 1000 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 study area. 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
the study area 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 identified as destroyed. Only four wells that might act as
potential migration conduits to deeper aquifers were identified.
One of these wells is a Santa Clara Valley Water District (SCVWD)
well more than 1000 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 Pacific
Gas & Electric. This type of well is frequently installed to
inhibit rust in underground pipelines. These wells are typically
shallow (i.e. 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. Well ID 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.

1.7 SURFACE AND SUBSURFACE STRUCTURES

Surface and subsurface structures involving the use of chemicals is
limited to the AMD 901/902, Signetics and TRW Microwave operable

Page 16 of 108
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units. These are the only areas were chemical use has been
documented. The structures are similar within each operable unit,
however the number and location is different enough to warrant a
discussion focused on each operable unit.

1.7.1 AMD Operable Unit

The surface area included in the AMD 901/902 operable unit is
approximately 3 acres with the physical surface structures covering
about 0.6 acres. Subsurface structures at the AMD 901/902 facility
include both structures installed in vaults below engineered grade
and structures installed directly into native soils. These
structures include waste solvent tanks and acid neutralization
systems (ANS). One above grade waste solvent tank in the Pad II
area (Figure 8) was installed in 1972 or earlier. This tank was
removed in 1982 and replaced with a 1000 gallon below grade steel
unit. This new tank, installed in a coated concrete vault, is still
in use.

Separate acid neutralization systems were maintained for each
fabrication facility (901 and 902). The acid neutralization system
for the 901 facility was installed in the Pad I area (Figure 8) in
1968 and removed in 1982. The ANS for AMD 902 was installed in the
Pad II area in 1972. This system was excavated and removed in 1984.
Each system consisted of a single coated concrete tank of about
2000 gallon capacity.

New acid neutralization systems were installed in 1982. The A-
system for AMD 901 and the B-system for AMD 902. Both systems are
fiberglass reinforced tanks installed in below grade coated vaults.
Each system consists of three tanks with a total capacity of 2000
gallons.
1.7.2 Signetics Operable Unit

Above ground structures at the Signetics facility include the 811
East Argues building, a building at 440 Wolfe and buildings at 830
and 815 Stewart Drive (Figure 2). The remedial investigation has
included groundwater monitor wells, soil samples and/or soil gas
studies near all four buildings. The investigation has focused on
underground structures and the primary source of contamination at
the 811 East Argues building.

In general underground structures at the Signetics facility can be
grouped into three categories; diesel tanks, waste solvent storage,
and waste water storage or treatment tanks. A waste solvent tank
located on the west side of the 811 E. Arques building was removed
in 1982 (Figure 9). Waste water treatment tanks located north of
the 811 building were removed in 1984.
Page 17 of 108
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"PAD I"—
ACID
NEUTRALIZATION
SYSTEM(I984)
'PAD I '•
ABOVEGROUND
/? WASTE SOLVENT
V TANK
(1982)
"PAD I"
WASTE DRUM
STORAGE
(1982)
"PAD IE"
WASTE DRUM
STORAGE
(1982)
19-D
MMFMtr
fuma
JIIIIIMI

Illlllllllll
"PADI"^
ACID
NEUTRALIZATION
SYSTEM(I983)
ii
(RDR
•

o
! nil jonwr mt-toum mr

mi sasva H n-. n-.

ontcamwau
SCALE: 1" = 90'
Figure 8. Historical Waste Storage Locations at AMD 901/902
(with removal dates in parentheses)
-------
SIGNETICS
611 BUILDING
OKN STOMOCI \_ _*_
Figure 9. Waste Storage Locations at Signetics
-------
Currently four underground diesel fuel tanks are in place on the
west side of the 440 Wolfe building and one underground diesel tank
is in place on the east side of the 811 E. Argues building.
Groundwater monitor wells located downgradient of the diesel tanks
are monitored quarterly. Two underground waste solvent tanks are
located on the west side of the 811 East Argues facility near the
waste water treatment plant. The facilities on the east side of the
811 East Argues building are located in concrete vaults. Two waste
water equalization tanks are located at the northeast corner of the
811 East Argues and two additional waste water neutralization tanks
are located at the northeast corner of the 440 Wolfe facility.
Groundwater monitoring wells are also located downgradient of these
tanks.

1.7.3 TRW Operable Unit

The former TRW Microwave facility at 825 Stewart Drive is one of
three structures on an approximately 1 acre site. The investigation
has been focused on the 825 Stewart Drive building. Two below
ground facilities have been documented at the TRW site. These
include an acid neutralization system north of the building and a
waste solvent storage tank (Figure 10). The acid neutralization
system was installed in 1968 when the facility began operation. The
first tank in a series of four underground waste solvent tanks was
installed in 1970 and was replaced sequentially in 1973, 1976, and
1980. The final underground solvent tank was removed in 1983. The
acid neutralization system was removed in 1986 and replaced by a
three tank above ground system.

1.7.4 Offsite Operable Unit

Structures within the offsite operable unit are primarily retail or
residential. The exceptions to this is the former Sunnyvale High
School site just north of the Signetics 440 Wolfe facility (Figure
2) and the San Miguel School site located near the corner of San
Miguel and Alvarado Avenues (Figure 2).

2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

Separate Orders have been prepared by the RWQCB for each onsite
Operable Unit (AMD, Signetics and TRW) with joint tasks for the
Offsite OU unit. This course has been taken due to the commingling
of the groundwater plume in the offsite area. The Companies are
encouraged to submit joint reports when feasible. A joint RI/FS was
completed and served to further define the groundwater contaminant
plume. If joint reports are not coordinated and submitted, each
company is still individually responsible for the joint tasks in
these Board Orders.
Page 20 of 108
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Chemical
Storage Yard I
m&SBJt$$iSi$M&&

Underground Solvent Tank^.
Existing & Former
-------
2.1 HISTORY OF SITE ACTIVITIES

As discussed above, conversion of the agricultural land in the
Santa Clara Valley to industrial use began in the late 50's and
escalated in the 60's and 70's with the establishment of Santa
Clara as a center of the electronics industry. The three industrial
facilities included in this ROD have been a part of this pattern of
development.

2.1.1 AMD Operable Unit

AMD 901 has been used as a semiconductor manufacturing facility
since 1969 to the present. Manufacturing operations at AMD 902
began in 1972 and are still active. The manufacturing process at
these two facilities involved the use of solvents for cleaning and
degreasing, acids for etching, caustics for acid neutralization and
some arsine and chromium in the manufacturing process.

Initial investigation at the AMD 901/902 site began in 1982 with
the investigation of leakage from an acid neutralization system
near AMD 901. This leakage was investigated and the acid
neutralization system was removed during 1983. In 1984 the
investigation expanded to include the acid neutralization system at
AMD 902. Polluted soils were found near both acid neutralization
systems.

The polluted soils were identified as point sources that had
resulted in groundwater pollution with volatile organic chemicals
(VOCs). Further investigation and interim remedial actions followed
the soils investigation.

The original development of the property was begun by Johnson and
Mape. The property at 901 Thompson Place was acquired from Johnson
and Mape by B/6 Management in 1977. The property at 902 Thompson
Place was acquired from Johnson and Mape by Mr. and Mrs. Edwin
Rosenthal in 1974. Partial interest in the 902 property was sold by
Mr. and Mrs. Rosenthal in 1982. The remaining interest was sold in
1984. The purchase of these interests was converted into two
undivided 50% interests in the property at 902 Thompson Place for
Research Group 82-1 and Thompson Place 2, limited partnerships.
These are the current property owners of record for AMD 901/902.
AMD has been the sole tenant and operator of the facilities and has
assumed responsibility for the cleanup actions at the site.

2.1.2 Signetics Operable Unit

Signetics has operated a semiconductor manufacturing facility at
the 811 E. Arques Avenue since 1964. The manufacturing processes
employed at this location have utilized various organic solvents,
acids, corrosives, and metals. Current chemical usage is similar to
past patterns, with the exception of the closure of the plating

Page 22 of 108
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operation at 811 E. Argues, which has eliminated some potential
sources of metal pollution, and the elimination of chemicals
containing chromium, phenol, trichloroethylene (TCE), and
perchloroethylene (PCE).

Initial investigation at the site began in February 1982 with the
detection of a leak in an underground waste solvent storage tank.
The presence of contaminated soil was verified during the tank
removal. Following additional investigation of the Signetics main
campus facility (440 Wolfe, 815 Argues, 830 Argues) the waste
solvent tank area has been identified as the principal source of
contaminants on the Signetics site.

All storage and treatment facilities have been updated and either
relocated above ground or doubly contained. Hazardous materials
from other nearby Signetics facilities are stored at the 811 E.
Argues site, under the authority of the Resource Conservation and
Recovery Act (RCRA), prior to offsite disposal at an appropriate
commercial disposal facility. Recent facility inspections and
reporting indicate that the facility is in compliance with the
requirements of its RCRA permit.

2.1.3 TRW Operable Unit

Initial operation as an industrial facility began in 1968 when
Aerotech Industries began assembling and testing microwave
components at this site. The first semiconductor manufacturing
began in 1970. Aerotech Industries and this site were acquired by
TRW Microwave in 1974 and was operated by TRW Microwave from July
1974 to August 1986. The property was purchased by Tech Facility 1,
Inc. in 1987. Some assets at this site were acquired by FEI
Microwave, Inc. in July 1987. The manufacturing facility is
currently operated by FEI Microwave, Inc.

While processes have varied throughout the history of the site,
chemical usage has remained relatively constant. Solvents, metals,
and acids have been involved in the manufacturing process. FEI
Microwave is currently manufacturing electronic components at the
facility.

As a result of responses to an information guestionnaire regarding
underground tanks investigation of pollution at the 825 Stewart
Drive site was initiated 1983 at the request of Board Staff. The
initial phase of investigation produced evidence of soil pollution
with a variety of volatile organic chemicals (VOCs). Investigation
at the site has focused on the location of an underground solvent
storage tank and acid neutralization system.

Page 23 of 108
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possible polluted soil that might still remain near the identified
point sources. All underground storage and treatment systems for
solvents and acids have been removed and replaced with above ground
systems.

2.2 HISTORY OF SITE INVESTIGATIONS

Initial investigations at all three industrial sites were initiated
as a result of an information questionnaire regarding underground
tanks. This questionnaire was mailed by the RWQCB to over 2000
industrial facilities in Santa Clara County as a follow-up to the
discovery of groundwater contamination at other sites in Santa
Clara County.

The sites were proposed for inclusion on the National Priority List
or Superfund list between 1984 and 1988. As required by Superfund
proposed final Remedial Investigation and Feasibility Study reports
(RI/FS) were submitted on behalf of AMD, TRW, and Signetics (the
Companies) in January 1991. Final RI/FS reports were submitted in
March 1991. The Regional Water Quality Control Board (RWQCB)
adopted an Order approving the joint RI/FS and a final Remedial
Action Plan that will encompass cleanup at the four Operable Units
including AMD, Signetics, TRW Microwave and the offsite area.

2.2.1 AMD Operable Unit

Two possible sources of pollution have been identified at the AMD
901/902 OU. These include acid neutralization systems south of the
AMD 902 building and north of AMD 901 (Figure 8). Soil pollution
was the highest near the AMD 901 acid neutralization system. During
removal of the system, soil with up to 186,000 fig/kg of
trichloroethylene (TCE) was excavated. Due to proximity of the
building not all of the polluted soil could be removed from the
southern portion of the excavation.

Additional investigation of source area soil was completed in 1988.
This investigation confirmed the presence of polluted soil beneath
the excavation for the acid neutralization system removed near the
AMD 901 building. The maximum concentrations detected in soil
include 242,000 pg/1 of 1,2-dichlorobenzene (DCB), 35,000 /*g/l of
tetrachloroethylene (PCE), 80,000 /*g/l of TCE, and 72 j*g/l of 1,1-
dichloroethylene (1,1-DCE). The estimated volume of soil remaining
in this area containing levels of total VOCs higher than 1 ppm is
37 cubic yards.

An acid neutralization system was also removed from the vicinity of
AMD 902 in 1984. The maximum concentration of soil pollution
detected during the investigation of the neutralization system was
1200 pg/kg of TCE, directly beneath the former tank location. No
other soil pollution above 100 pg/kg was detected during this
removal action. Based on analysis of soil following the excavation
and concentrations of pollutants in groundwater in the area of the

Page 24 of 108
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excavation no additional investigation of the AMD 902 source area
was required.

2.2.2 Signetics Operable Unit

Following the discovery of the leak in the waste solvent tank west
of the 811 E. Argues building a systematic review of potential
source areas was completed. Five possible source areas were
investigated in detail and a more wide ranging soil gas survey was
completed in an attempt to locate a possible unknown source. The
areas investigated include the former underground waste solvent
storage tank, the 440 Wolfe facility, Main Campus diesel tanks,
Main Campus wastewater neutralization tanks, and the former
location of wastewater neutralization tanks north of the 811 Argues
facility (Figure 9). In addition a soil gas survey was completed in
the vicinity of the 815 Stewart Drive building.

The results of these investigations have identified two probable
source areas of volatile organic chemicals (VOCs) within the
Signetics OU, the former underground waste solvent tank area and
the former 811 Argues wastewater neutralization tank area. Based on
the results of these investigations other source areas are not
anticipated.

2.2.3 TRW Operable Unit

As a result of responses to an information questionnaire regarding
underground tanks circulated by the RWQCB, investigation of
pollution at the 825 Stewart Drive site was initiated in 1983 at
the request of Board Staff. The initial phase of investigation
produced evidence of soil pollution with a variety of volatile
organic chemicals (VOCs). Investigation at the site has focused on
the location of an underground solvent storage tank and acid
neutralization system (Figure 10).

Additional soil work was completed in 1983 and initial groundwater
investigation began in July 1983. In addition to VOCs, metals were
detected in soil near the acid neutralization system. A more
comprehensive soil investigation was completed in 1988 to address
possible polluted soil that might still remain near the identified
point sources. The excavation was expanded to the limits allowed by
the proximity of the building. This area was identified as a point
source for chemicals that resulted in groundwater pollution.

Page 25 of 108
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Additional investigation was completed in 1988, as required under
RWQCB Order 88-015, since some contaminated soil was left in place
near the former location of the underground waste solvent storage
tank. The maximum concentration of total VOCs detected in the
vadose zone near the solvent storage tank was about 4 ppm. The
maximum concentration of total VOCs in saturated zone soil in this
area was approximately 34 ppm. Based on these estimates, and making
liberal assumptions regarding concentration and volume, it is
estimated that the vadose and saturated soils in this area contain
at most three pounds of TCE.

Soil investigation near an underground, acid neutralization system
(ANS) was also carried out during the closure of the system in
1986. Some soil samples contained elevated levels of metals,
however no elevated levels of VOCs were detected during this
investigation. This area is not considered a source area for
pollutants currently detected in the groundwater. Extraction tests
on soil from the ANS excavation area indicate that the inorganics
would not be expected to impact groundwater.

2.3 HISTORY OF ENFORCEMENT ACTIONS

The three industrial sites have been proposed or included on the
National Priorities List (NPL) and have been regulated by Regional
Board Orders as separate entities, as indicated herein:

2.3.1 AMD Operable Unit

a. October 1984 Site proposed for inclusion on
the National Priorities List
(NPL)

b. September 1985 Waste Discharge Requirements
Adopted

c. June 1986 Site formally added to the NPL

d. December 1987 Site Cleanup Requirements Adopted

e. April 1989 RWQCB Order #89-56, Revised Site
Cleanup Requirements Adopted,
approving RI/FS workplan and
associated tasks,

f. June 1991 RWQCB Order #91-102, Revised site
cleanup requirements, approving
the RI/FS and proposed plan
adopted.
Page 26 of 108
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2.3.2 Signetics Operable Unit
a. April 16, 1983

b. October 1984
Waste Discharge Requirements
Adopted,

Site proposed .for inclusion on
the National Priorities List
(NPL),
c. September 18, 1985
d. December 16, 1987
Waste Discharge Requirements
Adopted,
Site Cleanup
Adopted,
Requirements
e. July 20, 1988

f. April 1989

g. July 1989

h. October 1989

i. June 1991
2.3.3 TRW Operable Unit

a. June 1984

b. October 1985

c. January 1988

d. June 1988
Waste Discharge Requirements
Adopted approving RI/FS workplan
and related tasks,

RWQCB Order #89-058 Revised Site
Cleanup Requirements Adopted,
approving RI/FS workplan and
related tasks.

Waste Discharge Requirements
Amended,

EPA drops proposal to include
Signetics on the NPL,

RWQCB Order #91-104, Revised site
cleanup requirements, approving
the RI/FS and proposed plan
adopted.
Cleanup
Issued
and Abatement Order
Waste Discharge Requirements
Adopted

Site Cleanup Requirements Adopted

Site proposed for inclusion on
the National Priorities List
(NPL).
Page 27 of 108
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e. April 1989 RWQCB Order #89-057 Revised Site
Cleanup Requirements Adopted,
approving RI/FS workplan and
related tasks.

f. September 1989 Reissued Waste Discharge
Requirements Adopted

g. February 1990 Site formally added to the NPL

h. June 1991 , RWQCB Order #91-103, Revised site
cleanup requirements, approving
the RI/FS and proposed plan
.- adopted.

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 901/902,
Signetics and TRW Microwave. The Board published a notice in the
San Jose Mercury 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 an additional 30 days through
May 20, 1991.

In response to comments received at the March 20, 1991 meeting, an
additional meeting was held in early May. The initial focus of this
meeting was on parents of children utilizing the San Miguel School
facilities. After further discussion with other community members
the focus of the meeting was broadened to include the surrounding
community. Following this meeting several additional informal
meetings were held with community members and groups during the
extended public comment period.

Additional comments regarding the proposed cleanup plan were
received at the RWQCB meeting June 19, 1991. These comments
emphasized citizens concern regarding vapor emission in the off site
area and the impact of the Superfund status of the offsite area on
local property values.

3.2 Fact Sheets

Fact Sheets were mailed to interested residents, local government
officials, and media representatives. Fact Sheet 1, mailed in

Page 28 of 108
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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.

Fact Sheet 3, a summary and refinement of Fact Sheet 2, was hand
delivered to all residences in the offsite area in early May to
announce the May 7 meeting at the San Miguel School.' Fact Sheet 4
describing the final proposed plan and containing a summary of
responses to key community issues was hand delivered to all
residences in the offsite area and mailed to a 400 person mailing
list in early June.

4.0 SCOPE AND ROLE OF THE RESPONSE ACTION

4.1 SCOPE OF THE RESPONSE ACTION

The remedies selected and described in this ROD include the
existing interim remedial measures. The interim remedial measures
have included the removal of leaking underground tanks, acid
neutralization systems, and some contaminated soils, containment
and extraction of contaminated groundwater, and treatment of
extracted groundwater. The remedies selected and interim remedial
measures to date are explained by operable unit in the following
sections.

4.1.1 AMD Operable Unit

4.1.1.1 AMD Interim Remedial Measure

Onsite interim remedial actions began in 1983 with the removal of
the acid neutralization sump and about 103 cubic yards of soil at
AMD 901. Not all of the polluted soil was removed due to possible
structural damage to AMD 901. In 1984, the acid waste
neutralization sump and about 114 cubic yards of soil were removed
from the vicinity of Building 902.

Remediation of the groundwater began in 1984 with the installation
of two dewatering sumps and one extraction well to contain the
onsite pollution. One sump extracts water from the shallow A
Aquifer; the other two systems extract water from the Bl Aquifer.
Three additional extraction wells were installed in 1988 to enhance
the containment of the groundwater pollution in the B2 Aquifer.
The extracted groundwater is treated by an air stripper with vapor-
phase GAC emission control, and all of the effluent is reused as
process water at the AMD 901/902 facility. Figure 11 shows the
layout of the groundwater extraction and treatment system.

Page 29 of 108
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EXPLANATION
AWO MtLLS
(ENONCCRINC-SOENCC)
• 13-0 SKOM SvK Co»n»nU»n«
(a - Ion,) (-00 oo« -ODD
SGNCTICS MCUS (EMCON)

• S-TM »«!»• •••(*.
TRW NCOS (WEISS ASSOC.)
C - C* C.elogk OOM
Ux.llox
P0r DUALITY
L .NAL
Figure 11. AMD 901/902 Groundwater Extraction System
-------
4.1.1.2 AMD Selected Remedy

Excavation and offsite treatment and disposal is the selected
remedy for the 37 cubic yards of contaminated soil that remains
beneath AMD Building 901. The selected remedy for the AMD onsite
groundwater is the continuation of the present groundwater
extraction and treatment system involving air stripping with carbon
adsorption of the offgas as permitted by the BAAQMD.

The treated groundwater is currently reused as process water by the
manufacturing facility. All industrial process water is discharged
to the sanitary sewer, and thus indirectly to the publicly owned
treatment works (POTW). This discharge is controlled by a permit
from the POTW and is subject to EPA pretreatment regulations. The
discharge to surface water from the POTW is also controlled by an
NPDES permit. The POTW has operated within all limits set by the
NPDES permit.

The manufacturing operation will be eliminated at the AMD 901/902
facility in the near future and AMD has applied for an NPDES permit
for the discharge of the treated effluent from the groundwater
treatment system. No permit has been issued and discharge limits
have not been established. It is probable that the discharge limits
will be similar to those recently established for the AMD 915
facility included in this ROD as Table 3. A deed restriction will
be included in the remedy to prohibit the installation of onsite
wells until the groundwater remediation is completed.

4.1.2 Signetics Operable Unit

4.1.2.1 Signetics Interim Remedial Measure

Contaminated soil has been removed from three separate locations,
an underground solvent storage tank located west of the 811 E.
Argues building, a waste water neutralization tank area, also north
of the 811 E. Argues building, and soil removed during the
construction of the extraction trench at Signetics' 440 Wolfe
facility. Approximately 4,720 cubic yards of soil was removed from
the area of the waste solvent storage tank area in 1983. The
volume removed from the wastewater tank area is unknown, however,
based on analyses of soil from the excavation, it appears that all
soil above 1 ppm total VOCs was removed from this area. The soil
removed from the area of the 440 Wolfe trench is insignificant and
does not represent soil removal from a source area.

Previous soil investigations have not documented a source area for
the elevated levels of contaminants detected in wells north of the
811 Argues building. Based on results of a 1988 soil vapor
extraction test, three additional vapor extraction wells were
installed in 1989 and the system continues to operate.

Signetics operates six separate groundwater extraction systems in

Page 31 of 108
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the vicinity of 811 E. Argues (Figure 12). In 1982, initial
extraction of groundwater in the A aguifer began shortly after the
discovery of pollution. This was accomplished with the basement
dewatering sumps surrounding the 440 Wolfe Building, downgradient
of 811 E. Argues. Similar systems also operate in the northern
portion of the 811 Building and the wastewater treatment building.

Three other extraction systems were designed and installed
specifically to contain polluted groundwater to the Signetics
property. An extraction trench system was installed in the A
aquifer north of 440 Wolfe Road in 1984 and operation began in
1985. Operation of this trench has been continuous with the
exception of maintenance. Due to low water levels resulting from
the drought and long term groundwater withdrawal, the system has
been operating cyclically.

An extraction trench was installed in the A Aguifer north of the
811 E. Argues Building in 1984. The intent of this trench was to
intercept polluted groundwater that may have come in contact with
the polluted soil remaining in place at the 811 site. After an
initial period of effective recovery of polluted groundwater, this
trench became ineffective. This is again an effect of the low
water levels resulting from the current drought.

The third groundwater extraction system consists of a series of six
wells north of the Signetics facility at 815 E. Stewart Drive.
This system was intended to prevent further migration of polluted
groundwater downgradient to the north across the Signetics property
boundary. The system consists of three A Aguifer wells, one Bl
Aguifer well, and two B2 Aguifer wells. Operation of this system
began in 1987 and, with the exception of downtime for maintenance
operation, has been continuous to date. Extraction rates from the
B2 Aguifer were increased in 1990.

All extracted groundwater is treated by a common treatment system
utilizing air stripping and carbon adsorption on air stripper
offgas and as final polish on the water. The treatment system is
located at the 440 Wolf Road Building. The treated groundwater is
currently 100% reused as industrial process water or for nonpotable
uses. In the event of temporary plant shutdown the water will be
discharged to surface waters following treatment under an NPDES
discharge permit.

4.1.2.2 Signetics Selected Remedy

The selected remedy for the Signetics property combines soil and
groundwater cleanup measures and expands the existing interim
remedial measure's systems. Groundwater extraction from the A and
B Aquifers will be enhanced by the installation of some additional
extraction wells and an increased pumping rate at the 440 Wolf
extraction trench. The soil vapor extraction system will also be

Page 32 of 108
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Figure 12. Signetics Groundwater
Extraction System
-------
expanded by the addition of at least four more vapor extraction
wells. The vacuum pumps and the carbon treatment units would be
expanded to accommodate the additional wells. Deed restrictions
will prohibit the installation of drinking water wells until the
remediation is completed.

The discharge to surface water is controlled by NPDES Permit No.
CA0028720. The limits for this discharge includes instantaneous
maximum limits for specific contaminants and limits for receiving
waters including pH, nitrogen and dissolved oxygen. This permit
includes limits for the discharge of two waste streams, one from a
reverse osmosis treatment system used in the manufacturing process
(Waste 1) and the other (Waste 2) the discharge from the
groundwater treatment system. 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.

TABLE 1 - NPDES DISCHARGE LIMITS, SIGNETICS

Waste 001

Instantaneous
Maximum Limit
Constituent (mg/1)

Total dissolved solids 2000
Chlorine 0.0

Waste 002

Instantaneous
Maximum Limit
Constituent (nq/1)

Trichlorofluoromethane 5
1,1,1-trichloroethane 5
Tetrachloroethylene 5
Trichloroethylene 5
Ethylbenzene 5
Dichlorobenzene 5
1,1 Dichloroethylene 5
Xylenes 5

4.1.3 TRW Operable Unit

4.1.3.1 TRW Interim Remedial Measure

Interim actions to deal with soil pollution began in 1983 with the
removal of the underground waste solvent storage tank and some
associated.polluted soil. Additional soil was removed from this

Page 34 of 108
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same area in 1984. All the polluted soil could not be removed due
to the proximity of the foundation of the 825 Stewart building to
the excavation. The total soil removed for offsite disposal from
the solvent tank areas was 120 cubic yards. Soil pollution near
the waste solvent tank was investigated again in 1988 to determine
what levels of soil pollution remain in place near 825 Stewart.
The highest levels of soil pollution sampled in the unsaturated
zone by this investigation were 4 ppm total VOCs. Levels of VOCs
found in the saturated zone were as high as 34 ppm.

Investigations in the area of the underground acid neutralization
system and its associated piping system were completed in 1985 and
1986. No VOCs were detected in either area, however some areas of
possible metals pollution were located.

Initial actions to deal with groundwater pollution at the TRW
operable unit began in 1984 with the installation of an eductor in
the waste solvent tank excavation. Additional extraction wells
were created in 1984 by the conversion of some existing monitoring
wells. Groundwater extraction currently involves seven extraction
wells, three A Zone wells, three Bl Aquifer wells, and one B2
extraction well (Figure 13).

The extracted groundwater is treated by an air stripping system at
the 825 Stewart site. Uncontrolled air emissions are currently
regulated by a BAAQMD permit for this site. After treatment, the
water is released to Calabazas Creek under an NPDES permit.

4.1.3.2 TRW Selected Remedy

The selected remedy for the onsite plume at TRW consists of
continuing with the present groundwater extraction and air stripper
treatment system. If air emissions exceed those levels permitted
by the BAAQMD, air emissions control technology will be added to
the air stripper. Treated effluent will continue to be discharged
to Calabazas Creek under an NPDES permit.

The discharge to surface water is controlled by NPDES Permit No.
CA0028886. 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 2.
Page 35 of 108
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SIGNETICS
848
Treatment system
.1-1 /cr ruiik
&3SE**
SIGNETICS
830
Figure 13. TRW Groundwater Extraction System
-------
TABLE 2 - NPDES DISCHARGE LIMITS, TRW
Constituent
Instantaneous
Maximum Limit
VOC's
Trichlorofluoromethane
1,1,1-trichloroethane
Tetrach1oroethy1ene
Trichloroethylene
1,1 Dichloroethylene
Vinyl Chloride
1,2-Dichloroethylene
Methylene Chloride
Total VOC's

AROMATICS
METALS
Arsenic
Cadmium
Chromium (VI)
Copper
Cyanide
Lead
Mercury
Nickel
Silver
Zinc
5.0
5.0
4.0
5.0
5.0
0.5
0
0
6
5
25. O1
Ethylbenzene 5.0
Dichlorobenzene 5.0
Xylenes 5.0
Total Petroleum Hydrocarbons 50.0
20.0
10.0
11.0
20.0
25.0
5.6
1.0
7.1
2.3
58.0
1. The pH of the discharge shall not exceed 8.5 nor be less
than 6.5.

2. Toxicity: The survival of rainbow trout in 96-hour
bioassays of the effluent as discharged shall be a median
of 90% survival and a 90 percentile value of not less
than 70%
'The total.VOC Hmit is the sum of all EPA 601 compounds.

Page 37 of 108
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4.1.4 Offsite Operable Unit

4.1.4.1 Offsite Interim Remedial Measure

Two offsite groundwater containment extraction systems have been
installed (Figure 14). The Duane Avenue Extraction system,
consisting of nine extraction wells, is located just south of Duane
Avenue, approximately 1200 to 2100 feet downgradient (north) of
AMD, Signetics, and TRW facilities. This extraction system was
installed and began operation in 1986. The Duane Avenue system
extracts water from the A, Bl, 62, B3, and B4 Aquifers.

A second extraction system consisting of fourteen wells, along
Alvarado Avenue, approximately 2700 to 4300 feet downgradient
(north) of the AMD, Signetics and TRW facilities, was completed in
1988. Operation of the Alvarado Avenue system began in October
1988. This system extracts water from the A, Bl and B2 Aquifers.

All extracted groundwater is transferred by a piping system to the
AMD 915 DeGuigne facility where the water is treated by an air
stripper followed by a liquid-phase GAC polisher. About 30% of the
treated water is used as process make-up water by the AMD 915
facility and the remainder is released to a storm drain tributary
to Calabazas Creek under an NPDES permit. Uncontrolled air
emissions are currently regulated by a BAAQMD permit.

4.1.4.2 Offsite Selected Remedy

The selected remedy for the offsite commingled plume involves the
expansion of the current extraction system with some additional
wells and a continuation of the current air stripper treatment
system. The air stripper will include air emissions control if
emissions exceed levels permitted by the BAAQMD. Treated effluent
will continue to be reused as much as possible with the balance
being released to Calabazas Creek under an NPDES permit.

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: aa Table 3.
Page 38 of 108
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COMMA ICOU4SB1
COU3B2 I COM37A
COK55A fCOIOBI
oolites. Extraction Wen
Figure 14. Offsite Groundwater Extraction System
-------
TABLE 3 -NPDES DISCHARGE LIMITS, OFFSITE

Instantaneous
Constituent Maximum Limit
(M9/D
VOC's

Trichlorofluoromethane 5.0
1,1,1-trichloroethane 5.0
Tetrachloroethylene 5.0
Trichloroethylene 5.0
1,1 Dichloroethylene 5.0 '
Vinyl Chloride 0.5
cis-1,2-Dichloroethylene 5.0
trans-l,2-Dichloroethylene 5.0
Methylene Chloride 5.0
Total VOC's 10.O2

AROMATICS

Ethylbenzene 5.0
Dichlorobenzene 5.0
Trichlorobenzene 5.0
Xylenes 5.0
Total Petroleum Hydrocarbons 50.0

INORGANICS

Arsenic 20.0
Cadmium 10.0
Chromium (VI) 11.0
Copper 20.0
Cyanide 25.0
Lead 5.6
Mercury 1.0
Nickel 7.1
Silver 2.3
Zinc 58.0
*Total of constituents for EPA 601 analytes

Page 40 of 108
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4.2 ROLE OF THE RESPONSE ACTION

The purpose of the actions at AMD/Signetics/TRW is to control the
migration of polluted groundwater from the sites and to capture and
remediate existing contaminated groundwater. The intent of these
actions is to expedite cleanup of groundwater at these sites and to
prevent further movement of contaminated groundwater downgradient
and potential vertical migration into aquifers that currently serve
as drinking water sources.

The IRMs for groundwater have contained the groundwater
contamination plume to the sites and greatly limited the leading
edge in the offsite area. Vertical migration has been limited and
the toxicity, mobility, and volume of contaminants have 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.

5.0 SUMMARY OF SITE CHARACTERISTICS

5.1 SOURCES OF CONTAMINATION

5.1.1 AMD Source Investigation

Two possible sources of pollution have been identified at the AMD
901/902 OU. These include acid neutralization systems south of the
AMD 902 building and north of AMD 901 (Figure 8) . Additional
investigation of source area soil was completed in 1988. This
investigation confirmed the presence of polluted soil beneath the
excavation for the acid neutralization system removed near the AMD
901 building. The maximum concentrations detected in soil include
242,000 /xg/1 of 1,2-dichlorobenzene (DCB) , 35,000 /tg/1 of
tetrachloroethylene (PCE), 80,000 /*g/l of TCE, and 72 /itg/1 of 1,1-
dichloroethylene (1,1-DCE). The estimated volume of soil remaining
in this area containing levels of total VOCs higher than 1 ppm is
37 cubic yards.

An acid neutralization system was also removed from the vicinity of
AMD 902 in 1984. The maximum concentration of soil pollution
detected during the investigation of the neutralization system was
1200 ngfkg of TCE, directly beneath the former tank location. No
other soil pollution above 100 pg/kg was detected during this
removal action. Based on analysis of soil following the excavation
and concentrations of pollutants in groundwater in the area of the
excavation no additional investigation of the AMD 902 source area
was required.

A soil gas survey was completed around the AMD 901/902 buildings in
October 1989 to estimate the possible extent of soil contamination
and to attempt to locate any undocumented source areas. TCE was the
predominant contaminant in vadose zone soil gas ranging as a high

Page 41 of 108
-------
as 350 ftg/1 and averaging 63 /xg/1 in 19 out of 20 sample locations.
The distribution of soil gas contamination was not indicative of
additional source areas.

5.1.2 Signetics Source Investigation

Following the discovery of the leak in the waste solvent tank west
of the 811 E. Argues building a systematic review of potential
source areas was completed. Five possible source areas were
investigated in detail and a more wide ranging soil gas survey was
completed in an attempt to locate a possible unknown source. The
areas investigated include the former underground -waste solvent
storage tank, the 440 Wolfe facility, Main Campus diesel tanks,
Main Campus wastewater neutralization tanks, and the former
location of wastewater neutralization tanks north of the 811 Arques
facility. In addition a soil gas survey was completed in the
vicinity of the 815 Stewart Drive building.

The results of these investigations have identified two probable
source areas of volatile organic chemicals (VOCs) within the
Signetics OU, the former underground waste solvent tank area and
the former 811 Argues wastewater neutralization tank area (Figure
9). Based on the results of these investigations other source areas
are not anticipated.

5.1.3 TRW Source Investigation

Two possible sources of pollution have been identified at TRW.
These include an acid neutralization system and an underground
solvent storage tank area (Figure 10). Initial soil pollution
investigations focused on the area near the underground solvent
waste storage tank in 1983. Additional soil samples were collected
in July of 1984; the soil in these samples contained a variety of
VOCs including trichloroethylene (TCE), tetrachloroethylene (PCE),
and 1,2-dichloroethylene (1,2-DCE). The waste solvent storage tank
and some associated soil was removed in 1983. Additional soil
removal was completed in 1984. The excavation was expanded to the
limits allowed by the proximity of the building. This area was
identified as a point source for chemicals that resulted in
groundwater pollution.
;•*-"'
Additional" investigation was completed in 1988, as required under
RWQCB Order 88-015, since some contaminated soil was left in place
near the former location of the underground waste solvent storage
tank. The maximum concentration of total VOCs detected in the
vadose zone near the solvent storage tank was about 4 ppm.
Page 42 of 108
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5.2 DESCRIPTION OF CONTAMINATION

5.2.1 SOIL INVESTIGATIONS

5.2.1.1 AMD Operable Unit

Soil pollution was the highest near the AMD 901 acid neutralization
system. During removal of the system, soil with up to 186,000 /i£/kg
of trichloroethylene (TCE) was excavated. Due to proximity of the
building not all of the polluted soil could be removed from the
southern portion of the excavation.

An acid neutralization system was also removed from the vicinity of
AMD 902 in 1984. The maximum concentration of soil pollution
detected during the investigation of the neutralization system was
1200 pg/kg of TCE, directly beneath the former tank location. No
other soil pollution above 100 M9/k9 was detected during this
removal action. Based on analysis of soil following the excavation
and concentrations of pollutants in groundwater in the area of the
excavation no additional investigation of the AMD 902 source area
was required.

5.2.1.2 Signetics Operable Unit

Initial investigation of soil pollution began in 1982 following the
report of a leak in an underground solvent storage tank. Analyses
of soil samples from this initial phase of investigation indicated
that onsite soil was polluted with up to 8100 ppb TCE, 16,400 ppb
1-,1-,1-trichloroethane (TCA), 18,100 ppb xylene, and 79,000 ppb
butyl acetate.

Soil samples were collected from the base of the excavation at
various times in 1982. This follow-up investigation of polluted
soil remaining in place after the removal of the solvent storage
tank detected a variety of organic solvents. The greatest
concentrations detected were for TCE at 63,000 ppb, TCA at
1,700,000 ppb and PCE at 1,000,000 ppb.

The initial tank excavation was utilized as part of a larger
excavation for the installation of a new subsurface wastewater
treatment plant. Prior to beginning the larger excavation, a series
of borings was made throughout the planned excavation area. The
borings extended through the vadose zone into the saturated zone at
depths of 18 to 19.5 feet. Several soil "hotspots" were identified.
The maximum contamination that was detected was in boring S-54 with
6,700 ppb of TCE, 12,000 ppb of TCA, and 23,000 ppb of PCE. The
excavation removed soil into the saturated zone, at a depth of
about 20 feet. Based on the analysis of soil samples from the
borings this excavation should have removed all vadose zone soil
containing VOCs greater than l ppm total VOCs. However, based on
the absence of verification samples from the construction

Page 43 of 108
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excavation, additional A zone groundwater monitor wells were
installed in 1989 downgradient of the excavation. Low levels of
VOCs (19 ppb TCE) have been detected in these wells. These levels
are probably not indicative of remaining soil contamination in this
area.

5.2.1.3 TRW Operable Unit

Initial soil pollution investigations focused on the area near the
underground solvent waste storage tank in 1983. Additional soil
samples were collected in July of 1984; the soil in these samples
contained a variety of VOCs including trichloroethylene (TCE),
tetrachloroethylene (PCE), and 1,2-dichloroethylene (i,2-DCE). The
waste solvent storage tank and some associated soil was removed in
1983. Additional soil removal was completed in 1984. The
excavation was expanded to the limits allowed by the proximity of
the building.. This area was identified as a point source for
chemicals that resulted in groundwater pollution.

Additional investigation was completed in 1988, as required under
RWQCB Order 88-015, since some contaminated soil was left in place
near the former location of the underground waste solvent storage
tank. The maximum concentration of total VOCs detected in the
vadose zone near the solvent storage tank was about 4 ppm. The
maximum concentration of total VOCs in saturated zone soil in this
area was approximately 34 ppm. Based on these estimates, and making
liberal assumptions, regarding concentration and volume, it is
estimated that the vadose and saturated soils in this area contain
at most three pounds of TCE.

The remaining soil contamination is minimal and occurs at depths
greater than ten feet. The maximum vadose zone contamination is
about 4 ppm. With current technology it is not possible to separate
the higher levels of soil contamination in the saturated zone soil
from the groundwater contamination. However the remaining soil
contamination does not present any known impacts that will not be
remediated by the groundwater extraction system.
Page 44 of 108
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5.2.2 GROUNDWATER INVESTIGATIONS

5.2.2.1 AMD Operable Unit

The initial groundwater monitor wells were installed in 1983
following the excavation of the AMD 901 ANS. Additional wells have
been installed each year through 1989. Currently there are 30
monitoring wells and 6 extraction wells at the AMD 901/902 site.
Sampling of the AMD 901/902 well field was monthly from March 1985
through February 1986, and bimonthly until 1988. The sample plan
has called for quarterly monitoring of selected wells since 1988.

Based on this groundwater data TCE is the most common pollutant and
has been used as an indicator for groundwater pollution at AMD
901/902. Initial levels of groundwater pollution at this site were
as high as 100 ppm of TCE with total VOCs as high as 1000 ppm prior
to the point source removal in 1983. The highest current levels of
groundwater pollution are about 1 ppm TCE for the onsite area.
currently the onsite pollution extends to a depth of up to 65 feet.

5.2.2.2 Signetics Operable Unit

Groundwater pollution by VOCs was detected during the initial
investigation in 1982. Monitoring has been continuous for selected
wells on at least a quarterly basis since 1982. Groundwater
pollution has spread through the upper four aquifers. Additional
wells were installed in 1989 to provide additional characterization
of the extent of vertical pollution. The total number of monitor
wells installed in five water bearing zones at the Signetics OU is
96. The downgradient and lateral extent of contamination of
groundwater contamination at the Signetics OU is difficult to
quantify due to the commingling both laterally and downgradient.

The highest initial concentrations of TCE detected in the A aquifer
was 34,000 M9/1 in 1982 in well S049A. The highest concentration
of TCE in the A aquifer in October 1990 was 22,000 /xg/1 in well
S091A with groundwater from well S049A containing 12,000 ng/1 TCE.
The concentration in well S091A is an historic low for TCE in
groundwater from that well.

The highest initial concentration of TCE in the Bl aquifer was 2600
jtg/1 in 1982 in well S048B1 and 25,000 pg/1 in 1983 in well S075B1.
Currently the highest concentration of TCE in the Bl aquifer is
20,000 pg/1 at well S065B1. The highest concentration of TCE in
the B2 aquifer was 13,000 pg/1 at well S048B2 in 1986, 20,000 /xg/1
in 1988, and 8800 pg/1 at the same well. The highest initial
concentration of TCE in the B3 aquifer was 25,000 pg/1 of TCE in
well S101B3 in 1986. Currently the highest concentration of TCE in
the 63 is 740 j*g/1/ also measured in well S101B3. The maximum
concentration in October 1990 in an onsite B4 aquifer well at 811
E. Arques was 13 pg/1. This is the first occurrence of a chemical
of concern above drinking water standards in an onsite B-4 aquifer

Page 45 of 108
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well. '

The current volume of contaminated groundwater in the A aquifer is
estimated to be 1,353,600 cubic feet (10,125,631 gallons) and
10,516,500 cubic feet (78,668,883 gallons) in the B aquifer. This
estimate is based on the surface area of the Signetics OU and
average saturated thicknesses for the individual aquifer zones.

5.2.2.3 TRW Operable Unit

The initial groundwater monitor wells were installed at this site
by TRW in 1983, with additional wells installed in 1984, 1986 and
1989. There are twenty-five monitoring wells located within the TRW
operable unit. This includes wells installed by AMD and Signetics
as part of the RI. Monitoring of water levels and contamination has
been carried out on at least a quarterly basis for selected wells
since at least 1986. Based on this data the dominant VOC in the
groundwater is TCE, although 1,2-DCE, Freon 113, and PCE are also
frequently detected.

The highest initial levels of TCE in the groundwater were detected
in well T-2A. The highest concentrations of VOCs in the A aquifer
in 1990 were measured in groundwater from wells T-9A and T-7A (see
Appendix 1, figure 4), with the most recent concentrations being
approximately 2,300 and 1,700 pg/1, respectively. Contaminant
concentrations in these wells may be influenced by migration from
off site sources. Therefore these wells may not be representative of
A zone contamination at the TRW OU. Well T-2A (Figure 13), an
extraction well downgradient of the source area, detected about 100
jtg/1 of TCE and 200 pg/l of total VOCs in the October 1990
sampling. Groundwater pollution in the deeper aquifers was
originally the most concentrated in well T-2B. Currently the
highest TCE concentration in onsite wells is in well T-2B an
extraction well in aquifer Bl, with a concentration of 19,000 pg/1.
High levels of vinyl chloride (7800 pg/1) are also detected in well
T-2B.

5.2.2.4 Offsite Operable Unit

It was determined in 1984 that groundwater pollution had migrated
north, downgradient from point sources at TRW (FEZ) Microwave, 825
Stewart, and Signetics 811 Arques facilities. Initial investigation
began in September 1984. Several phases of investigation including
two soil gas surveys and the installation of 83 monitor wells, 23
extraction wells, and 22 piezometers. Additional pilot and soil
borings were also completed.

Offsite the pollution extends downgradient to the north for
approximately 4000 feet and to a maximum lateral extent of about
1600 feet. Contaminants have been detected to a depth of up to 100
feet in the B4 zone. Additional monitor wells will be required at
the distal edge of the plume to define the current extent of the

Page 46 of 108
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contamination plume. The pattern 'of vertical contamination
generally represents the standard model for contaminants that are
heavier than water, in that the depth of contamination increases
with distance from the source area.

The current volume of contaminated groundwater in the A aquifer in
the Offsite OU is estimated to be 1,490,600 cubic feet (11,145,974
gallons) and 41,140,000 cubic feet (307,748,571 gallons) in the B
aquifer. This estimate is based on the surface area of the Offsite
OU and average saturated thicknesses for the individual aquifer
zones.

5.2.3 AIR INVESTIGATIONS

5.2.3.1 AMD 901/902 Operable Unit

As part of the interim remedial action for groundwater, an air
stripper is in place at the AMD 901/902 OU. This air stripper has
a carbon unit filtering the air effluent. Current air emissions are
very limited and approximately 4.6 X 10~3 pounds per day of TCE is
released into the ambient air. In reviewing the original permit
application in 1985 the BAAQMD estimated the risk related to the
chemical releases from the AMD air stripper to be 1.6 X 10"*. It is
unclear if this evaluation was made with the activated carbon
treatment of the air effluent in place. What is certain is that
effluent concentration has declined since the original permit to
operate was issued in 1986. This decline would result in decreased
emission from the air stripper with an attendant decrease in risk.
The spent carbon is removed for offsite treatment and disposal.

Volatilization of groundwater contaminants from the subsurface was
not investigated for the AMD 901/902 OU since no current
residential property exists above or adjacent to the plume within
this operable unit. 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. A
review of this exposure pathway will be conducted to determine the
impact on future potential residents at the five year review
period.

Consideration of worker safety in the 901 facility due to the
possible off-gassing of VOCs from contaminated soil beneath the AMD
901 building was investigated due to agency comments (Appendix A).
This was not part of the RI/FS and these concerns are considered
more appropriate for regulation and evaluation by California
Occupational Health and Safety Association (CAL-OSHA).

Modeling that was done to estimate migration of vapors from
groundwater in the offsite OU would not apply to exposures in the
901 facility for several reasons. The model assumes that the

Page 47 of 108
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structure has a basement, crawl space, or a perimeter crack to
allow infiltration of the vapors. The AMD 901 is constructed on a
concrete slab and no extensive cracking of the slab has been
observed. Another component of the model is that 100% infiltration
is assumed and a limited number of air exchanges per hour occurs in
the average home. These two factors are major components in the
process of releases of contaminants from soil possibly getting
trapped and concentrated in indoor air.

As part of. the facility operation all areas of the building have
active ventilation systems which result in a greatly increased air
exchange rates and positive pressure. The active ventilation would
result in the removal of contaminants as they enter the indoor
space and the positive pressure would reduce the infiltration rate.
These two factors in combination would act to limit the possibility
of the vapors entering or becoming concentrated in indoor air in a
semiconductor manufacturing facility. Active ventilation systems,
sealing of slabs or below ground portions of structure, and
maintenance of positive pressure are major components of systems
designed for remediation of indoor air contamination.

In response to agency concern AMD sampled air in the interior of
the 901 facility with a photoionization detector (PID). PIDs are
not chemical specific, in that they will not indicate what chemical
is being detected, only an approximate concentration of chemicals
in vapor. The detection limit for this method is between 0.5 part
per million (ppm) and 1 ppm. All readings were below the detection
limit. To confirm these results summa canisters of indoor and
outdoor ambient air were collected and analyzed. These results
indicate that the chemicals present at high concentrations in the
contaminated soil, 1,1-Dichloroethylene (DCE), Trichlorethylene
(TCE), Tetrachloroethylene (PCE) and Dichlorobenzene (DCB), are not
present above 0.25 part per billion (ppb). The worker safety
regulations include allowable exposure for these chemicals from 25
to 200 ppm. These above factors all contribute to the conclusion
that worker exposure to indoor air contaminated by vapors migrating
from contaminated soil is not a significant risk at the AMD 901
facility.

5.2.3.2 Signetics Operable Unit

As part of the interim remedial action for groundwater three air
strippers are in place at the Signetics OU. The air strippers are
operated in sequence with the total flow being fed to one large
diameter stripping tower, the water is then captured and the volume
is split between the two remaining towers. The first air stripper
in the sequence has two parallel lines of eleven 150-pound drums of
granular activated carbon. It is estimated that the primary air
stripper removes about 99% of the total VOCs in the influent. The
vapor phase carbon system reduces air emission risk by over 90%.
The second set of air strippers reduces the remaining 1% of the
VOCs by an additional 88% to about 1 pg/1 in the treated

Page 48 of 108
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groundwater effluent. Under regulation of a BAAQMD permit to
operate, the air stripper system is limited to a maximum release of
0.52 pounds per day of VOCs to the atmosphere. The spent vapor
phase carbon is removed for offsite treatment and disposal.

The risk related to this release from the air strippers was
evaluated after the completion of the FS. This risk was evaluated
using a screening level model. The maximum concentration predicted
by the model was 0.434 pg/1. This would result in an estimated
increased cancer risk of approximately 1 X 10~*. Non-carcinogenic
effects were also evaluated for this release and none would be
predicted from the exposure to the maximum concentrations resulting
from the air stripper discharge.

Volatilization of groundwater contaminants from the subsurface was
not investigated for the Signetics OU since no current residential
property exists above or adjacent to the plume within this operable
unit. 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. A review of this
exposure pathway will be conducted to determine the impact on
future potential residents at the five year review period.

5.2.3.3 TRW Operable Unit

As part of the interim remedial action for groundwater an air
stripper is in place at the TRW OU. The air stripper air effluent
is uncontrolled, however due to the combination of low groundwater
effluent concentration and low extraction rate, the air emissions
from the air stripper are limited. It is estimated that the air
stripper releases about 0.84 pounds of VOCs per day. About 90% of
this total discharge is TCE. This release of contaminant is
regulated and permitted by the BAAQMD, however the BAAQMD did not
require risk screening at the time this permit to operate was
issued (1985). Evaluation of the risk included in the FS predicts
that the maximum concentration of VOCs released by the air stripper
at the TRW operable unit is 9.24 X 10'3 mg/m3: Since TCE is a
carcinogen and is the dominant chemical in the stripper influent
and stripper air emissions, the cancer risk related to this air
discharge was evaluated for TCE. The maximum concentration as
estimated by the model would occur at 0.191 kilometers from the air
stripper. Assuming that an individual was exposed to this
concentration for a period of thirty years would result in an
excess cancer risk estimate for this air emissions of 1.79 X 10"5.

5.2.3.4 Offsite Operable Unit

As part of the interim remedial action for groundwater in the

Page 49 of 108
-------
offsite area groundwater is extracted and piped for treatment to
the Advanced Micro Devices facility at 915 DeGuigne Drive in
Sunnyvale. The groundwater is treated by an air stripper followed
by aqueous phase granular activated carbon. The air effluent from
the air stripper is uncontrolled. It was estimated in the FS that
the air stripper releases about one and one-half pounds per day of
VOCs to the ambient air. The release from this air stripper system
was re-evaluated in September 1991. The influent volume and
concentration had declined. Mass balance estimates based on the
current flow rate and concentration indicate that VOC emission has
declined to about 300 pounds per year or 0.82 pounds per day. Based
on a model prepared by the California Air Pollution Control
Officers Association the risk related to this release is less than
1 X 10'*. This release of contaminant is regulated and permitted by
the BAAQMD. •

The baseline public health evaluation indicated that volatilization
of chemicals from groundwater could reach the surface. The risk
from this exposure pathway was evaluated based an modeling of the
transport of VOCs from groundwater through soil to the surface and
eventually entering residential buildings through cracks in
concrete slabs. This evaluation predicted a possible excess cancer
risk of l X 10"*.

Although the predicted risk was within the risk range allowed by
the NCP it was determined that additional investigation of this
pathway was warranted. The decision to proceed with additional data
collection was based on several considerations; this was the only
current pathway that had a high probability of being complete, the
groundwater plume is beneath a residential area including a child
care facility (San Miguel School), and modeling of vapor transport
is poorly developed and relatively speculative.

Additional data was collected through the use of a field flux
chamber. This provides a measure of the gross emission rate for a
known surface area of soil. The intent using this measurement
technique was to eliminate the modeling of vapor transport in the
vadose zone from the estimate. This would still require the
estimation of infiltration rate into structures and the fate of the
contaminants upon entering a structure. The other option considered
was the direct measurement of indoor air from selected structures.
This approach was rejected due to a lack of sampling protocol for
indoor air and the possible contamination of indoor air by indoor
sources.

Three sampling events for field flux measurements have occurred.
Two separate transects across the known groundwater plume were
included in the field sampling (Figure 15). One transect was in the
near source area in open fields. The second transect was near the
San Miguel School. The first transect was intended to provide a
"worst case" estimate of the field flux rate since it crossed the
groundwater plume where concentrations were the highest. The second
transect was intended to be representative of the flux rate in the
residential area.
Page 50 of 108
-------
APPROXIMATE GROUND-WATER
FLOW DIRECTION
WESTMOHOUSE
FACXJTY
EXPLANATION
3ANIA PAULA AVENUE
A-AquNr Zon» ExtracUon Wrf

Aprt 1991 TOE Concxrtrafcn. ppb

TCE CenoMMHon. Rfc
Ctairtcal taooonowMton contoun.
daatwd wfi«r» Mtrrad
Figure 15. Soil Flux Sample Location Map
Samplng Location, surface emission
isolation Mu« chamber
-------
Field flux data has measured very low concentrations of VOC's. The
scenario was. not as expected, in that TCE has been detected in the
offsite area and not in the near source area. Vinyl chloride was
detected in one of three sampling events at location 6 (Figure 15)
in the near source area. TCE has been detected in one sample
(location 9) from the off site area in two sample events and at
location 8 in the most recent sampling. Other chemicals, most
notably 1,1,1-TCA and Freon 113, are frequently detected in soil
flux gas -samples. Correlation between the occurrence of these
chemicals and groundwater is difficult since these chemicals do not
occur frequently or at high concentrations in groundwater.

The possible exposure to chemicals as a result of air emissions
from groundwater will be evaluated as part of the five year review
for all four operable units (TRW (FEI) Microwave, Signetics, AMD
901/902 and the associated offsite operable unit). This is a
relatively new exposure scenario and assumptions related to this
pathway are not well established. In addition, appropriate field
sampling methodologies are not well established. It -is anticipated
that additional data and techniques will be available at the five
year review.

6.0 SUMMARY OF SITE RISKS

6.1 TOXICITY ASSESSMENT

A baseline public health evaluation (BPHE) is completed for every
Superfund site. As part of this assessment the occurrence of
chemicals at a site is investigated to identify those chemicals
whose occurrence and tpxicity should be considered in the cleanup
of the site. Groundwater data collected after 1988 and all shallow
soil data was utilized in this evaluation. The BPHE did not
consider the groundwater data on the basis of operable unit where
the data was collected. Rather, since the groundwater is connected
throughout the operable units, geometric mean and maximum
concentration data was applied to the overall site regardless of
location of occurrence.

Based on very conservative assumptions regarding concentration,
distribution, toxicity, analytical data, and potential routes of
exposure, the BPHE for these three combined sites identified
twenty-eight "chemicals of potential concern" (Table 4) from this
database. This included seventeen organic chemicals and eleven
inorganic chemicals. The assignment of a chemical as a carcinogen
in Table 4 is based on its classification as a carcinogen by an EPA
Carcinogen Risk Assessment Verification Endeavor (CRAVE) workshop.
In addition to the criteria outlined above some of the 28 chemicals
were included based on detection in soil and mobility in the
environment though they have never been detected in groundwater.
Page 52 of 108
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TABLE 4
AMD 901, SIGNETICS, TRW DATA SUMMARY

Chemical
Antimony
Arsenic
Bar inn
Benzene
Cadmium
Chloroform
Chromiifn(Total)
Copper
1.2-0ichlorobenz«ne
I.T-Dfchtoroethane
' 1,1-0 ichl oroettierte
ci«- 1 ;2rD ichloroethene
trans- I, Z-
Dfchloroetliene
Ethylbenzene
Freon 113
Lead
Methylene Chloride
Nickel
Silver
Tetrach loroethene : v : ::. •'•!'
Thallium
Toluene
1;1 ,1 -Tr < ieh loroethane
Trichtoroethene
Tr i ch 1 orof I uoromethane
Vinyl Chloride
Xylene*
Zinc
CRAVE

A
D
A
B1
B2
A1
D
0
82
C
0
0
0
0
B2
82
D
D
•< -"-?/ 82-,''-'
0
D
&
82
0
A
D
E
GROUNDWATER
Max Value
(M/D
120
40
100
NS
38
140
160
97
330
600
740
8000
1800
NS
78,000 "
710
520
280
24
:;. 610- '
160
NS
1,000
290.000
1.2
32.000
NS
1,100
•Det/tMnal
6/13
7/13
2/5
NA
4/13
12/316
7/13
7/13
17/76
25/556
49/556
104/154
11/154
NA
;?;:*f 209/556
8/13
1/76
9/13
3/13
'.'•..''••• 88/670
8/13
NA
144/670
618/670
4/126
•V>r':-;'67/670;;::'':^::-;:i
NA
10/13
SOIL
Max Value
<*g/kg)
12
4.6
300
4.000
6.9
7
59
190
240.000
NS
NS
460
73
2.000
NS
66
26
250
NS
35.000
3.8
3.000
NS
80,000
NS
^:iWiB>>:-:;^:.::
4.000
67
«Det/ffAnal
3/6
4/6
6/6
1/5
4/7
3/14
11/11
7/7
11/14
NA
NA
11/14
1/14
1/5
"•NA-": "• .;•
5/7
4/10
7/7
NA
: 11/31
2/6
1/5
NA
23/31
NA
.':;i:?:'-. -0/5
1/5
7/7
NS > Not Sanplad
NA » Not Applicable
A * Known Hunan Carcinogen*
81 " Probable Human Carcinogen (United human evidence, adequate evidence fro* animals)
62 • Probable Hunan Carcinogen (inadequate human evidence, adequate evidence from animals)
C * Possible Human Carcinogen (limited evidence of carcinogenicity, animal studies only)
D > Not Classified as to Human Carcinogenicity (inadequate animal and human data or no data)
E » Not a Human Carcinogen (adequate evidence of non-carcinogenicity in adequate animal or human studies)
1 Chromium VI inhalation only
Page 53 of 108
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As part of risk management, further evaluation of the groundwater
data in the FS has resulted in the reduction of the number of
organic chemicals to ten chemicals of concern. All of the
inorganics were removed from the list of chemicals of concern based
on additional groundwater sampling that was not available when the
BPHE was completed and the fact that some of the inorganics
detected in soil were not used as part of the process at the
operable unit where the BPHE included the inorganics as chemical of
concern.

This final list of "chemicals of concern*1 includes (shaded in Table
4) 1,2-Dichlorobenzene (1,2-DCB), 1,1-Dichloroethane (1,1-DCA),
1,1-Dichloroethylene (1,1-DCE), cis-l,2-Dichloroethylene (cis-1,2-
DCE), trans-1,2-Dichloroethylene (trans-l,2-DCE), Freon 113,
Tetrachloroethylene (PCE), 1,1,1-Trichloroethane (1,1,1-TCA), TCE,
and vinyl chloride.

The rational for selecting these remaining ten chemicals as
chemicals of concern is as follows:

1. 1,1-Dichloroethane (1,1-DCA), 1,1-Dichloroethylene (1,l-DCE),
Tetrachloroethylene (PCE), and TCE are probable or possible
human carcinogens.

2. 1,2-DCB, Freon 113, PCE, 1,1,1-TCA TCE and Vinyl Chloride are
detected in groundwater at a greater than 10% frequency.

3. 1,1-DCA, 1,1-DCE, cis-l,2-DCE, and trans-1,2-DCE, are detected
in more than 5% of groundwater samples or are breakdown
products of one of the other chemicals of concern and
therefore might reasonably be expected to occur in increased
frequency, distribution or concentration.

4. 1,1-DCA, 1,1-DCE, cis-1,2-DCE, trans-1,2-DCE, Freon 113, PCE,
1,1,1-TCA, TCE, and vinyl chloride 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.

5. 1,2-DCB, 1,1-DCE, Freon 113, PCE, 1,1,1-TCA, and TCE, 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.

6. TCE has been used as an indicator chemical throughout the
study area. 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

Page 54 of 108
-------
the most widespread occurrence and has the highest
concentration in groundvater samples.

6.2 RISK CHARACTERIZATION

A Baseline Public Health Evaluation (BPHE) is conducted at every
Superfund site to evaluate the risk posed by the site in its
existing condition. The BPHE examines the chemicals present at the
site (see Section 6.1) and the possible routes of exposure to
humans and animals.

Using similarly conservative assumptions, the BPHE also developed
future and current exposure scenarios. For the hypothetical future
exposure scenarios, it was assumed that the onsite areas of the
site would be developed for residential use and that the
groundwater in the A- and B—aquifers would be used for domestic
water supply purposes. The potential current exposure scenario
considered in the BPHE evaluated inhalation of VOC vapors
originating from the offsite groundwater plume.

Fugitive dust emission or incidental ingestion of soil by
construction workers during hypothetical future construction on the
site were not evaluated as exposure pathways at these sites. This
choice was made because the documented contaminated soil is all at
depths greater than eight to ten feet. Fugitive dust emission is
not a concern in this circumstance. Standard construction practices
in this portion of the Santa Clara Valley would not result in
excavations of this depth.

According to the BPHE, potential future exposure routes at the
Companies site may include ingestion of groundwater containing the
chemicals of potential concern, inhalation of VOC vapors from
groundwater during showering or other domestic uses, and inhalation
of VOC vapors originating from the groundwater. Based on the
absence of known soil "hot-spots", other than those well below
ground surface and beneath buildings, direct contact exposure to
chemicals of concern was not considered further in the exposure
evaluation.

In addition to the above, the BPHE also assumed that the current
cleanup actions would be discontinued and cleanup measures would
not be implemented at any time in the future. Using these
assumptions, the BPHE concluded that the only average exposure
scenario for which there would be a potential health risk or an
increased cancer risk greater than 1 in 10,000 was the hypothetical
future domestic use of contaminated shallow groundwater. The most
crucial of these assumptions is that cleanup activity in the study
area would cease. This implies that current concentrations in
groundwater would persist into the future.

The only current exposure scenario identified in the BPHE is indoor
exposure to vapors migrating from the contaminated groundwater in

Page 55 of 108
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the offsite area. This pathway was evaluated for two separate
populations, residents of the offsite area and children attending
the San Miguel school. These cancer risks and health hazard
assessments are based on estimates of the indoor air concentrations
of the chemicals of concern predicted by mathematical models. The
predicted carcinogenic risk for the average case is estimated to be
about 4 in 100,000,000 for schoolchildren and about l in 10,000 for
residents. The model does not predict any toxic effects from this
exposure. This is within the risk range that would be allowable
under EPA guidance after cleanup. EPA methodology will be applied
to reassess this exposure within each of the four operable units at
the five year review.

The future use scenario considered by the BPHE is domestic use of
shallow groundwater beneath the site. This would expose residents
to contaminated groundwater through ingestion of water and
inhalation during domestic use (showering, cooking, etc.). The
greatest potential carcinogenic risk related to the average
exposure through these pathways is approximately 2 in 1000.

Domestic use is a hypothetical case since shallow groundwater in
the A- and B-aquifers is not currently used for water-supply
purposes and local ordinances prohibit such practice. Currently,
there are no plans to use the A- and B-aquifer groundwater as a
drinking water supply.

6.2.1 Soil

6.2.1.1 AMD 901/902 Soil

No shallow (less than 2 feet) contaminated soil is remaining since
the interim remedial actions for soil was effective in removing
shallow soil. Contaminated soil that remains in place is greater
than ten feet in depth. The exposure to contaminated soil through
the dermal contact route was not evaluated since it is unlikely
that contact with the chemicals of concern at AMD 901/902, VOCs,
would occur. Possible exposure of workers to the contaminants
remaining in soil in place at the AMD 901 facility as a result of
volatilization was investigated and will be discussed below under
risk from air pathways.

6.2.1.2 Signetics Soil

The interim remedial action of excavation and offsite disposal was
effective in removing contaminated soil from the Signetics operable
unit. No additional contaminated soil has been documented,
therefore risk due to direct contact or fugitive dust emission was
not evaluated.

6.2.1.3 TRW Soil

No shallow (less than 2 feet) contaminated soil is remaining since

Page 56 of 108
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the interim remedial actions for soil was effective in removing
shallow soil. Contaminated soil that remains inplace is greater
than ten feet in depth. The exposure to contaminated soil through
the dermal contact route was not evaluated since it is unlikely
that contact with the chemicals of concern at TRW, VOCs and metals,
would occur. Additionally, should dermal contact occur the VOCs
would volatilize into the air prior to significant subcutaneous
adsorption and subcutaneous adsorption of metals is not
significant.

6.2.1.4 Offsite Soil

No source areas have been located or are suspected in the offsite
operable unit. Soil contamination would only occur at contact
between the soil and groundwater, which occurs at depths greater
than twelve feet. Concentrations are assumed to be minimal due to
the constant partitioning of chemicals from water to soil and soil
to water. Risk due to direct contact or fugitive dust emission was
not evaluated.

6.2.2 Air

6.2.2.1 AMD 901/902

The risk from the air stripper emissions was evaluated by the
BAAQMD in 1985 prior to providing AMD with a permit to operate the
air stripper. The risk related to the chemical releases from the
AMD 901/902 air stripper was estimated by BAAQMD personnel to be
1.6 X 10~*. Flow rate and influent concentration was higher in 1985
than now therefore maximum air concentration and the related risk
would also be lower than that projected in 1985.

The potential for volatilization of chemicals from groundwater to
the surface was evaluated in the BPHE for the hypothetical case
that the "onsite" industrial property at the AMD 901/902, Signetics
and TRW operable units was converted to residential property. This
evaluation was based strictly on modeling of transport from
groundwater into residences and assuming current groundwater
concentrations for chemicals of concern. The excess cancer risk
estimate, based on this model is 4 X 10"5 for the average case and
8 X 10** for the maximum case. The non-carcinogenic cancer index
for both the average and maximum cases is much less than one.
• %
The portion of the groundwater contaminant plume that currently
beneath the AMD 901/902 operable unit does not represent a current
risk since 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 secondly the continued influx

Page 57 of 108
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of air dilutes any contaminants that enter the structure.

In response to agency concerns regarding the presence of
contaminated soil remaining below the AMD 901 facility, AMD sampled
air in the interior of the 901 facility with a photoionization
detector (FID). PIDs are not chemical specific, in that they will
not indicate what chemical is being detected, only an approximate
concentration of chemicals in vapor. The detection limit for this
method is . between 0.5 part per million (ppmj and 1 ppm. All
readings were below the detection limit. To confirm these results
discrete samples indoor and outdoor ambient air were collected in
summa canisters and analyzed. This sampling protocol allows much
lower detection limits. These results indicate that the chemicals
present at high concentrations in the contaminated soil, 1,1-
Dichloroethylene (DCE), Trichlorethylene (TCE), Tetrachloroethylene
(PCE) and Dichlorobenzene (DCB), are not present above 0.25 part
per billion (ppb). .

Worker safety regulations include allowable exposure for these
chemicals from 25 to 200 ppm. The worker allowable worker exposures
are risk based, however the assumptions used in assessing worker
exposure are significantly different from the assumptions used in
.the BPHE. The comparison of the non-detectable levels of the
chemicals of concern to the allowable levels would still indicate
that exposure to indoor air contaminated by vapors migrating from
contaminated soil or other sources is probably not a significant
risk at the AMD 901 facility.

6.3.2.2 Signetics

As part of the interim remedial action three air strippers are
present at the Signetics 440 Wolfe facility. The air strippers
operate in sequence, with the first air stripper removing over 99%
of the VOCs from the influent water. This initial stripper does
include control of the air emissions with capture by vapor phase
carbon. The total release of VOCs by all three air strippers is
limited to 0.52 pounds per day by a BAAQMD Permit to Operate. The
risk from the release from the air strippers was evaluated after
the completion of the FS. The maximum concentration predicted by
the model was 0.434 pg/1. This would result in an estimated
increased cancer risk of approximately 1 X 10"*. Non-carcinogenic
effects were also evaluated for this release and none would be
predicted from the exposure to the maximum concentrations resulting
from the air stripper discharge. The model assumed minimum stack
height, maximum predicted concentration and minimum distance to the
receptors at the property boundary.

The risk related to volatilization of chemicals, primarily VOCs
from groundwater, was evaluated for all three "onsite" operable
units for a hypothetical future scenario of conversion to
residential property as discussed above in section 6.3.2.1.

Page 58 of 108
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6.3.2.3 TRW

As part of the interim action and as part of the proposed remedy an
air stripper has been operating at the former TRW Microwave
facility since 1985. The emissions from this air stripper are
estimated to be 0.84 pounds per.day. TCE accounts for over 90% of
this emission. While vinyl chloride is detected routinely in one of
the onsite TRW wells it is not detected in the influent to the
treatment system. This is a function of dilution of the vinyl
chloride by mixing with groundwater from other extraction wells.
Therefore the cancer risk related to this release was evaluated for
TCE. The maximum concentration of VOCs estimated by the California
Air Resources Board PTPLU model is 9.24 X 10'3 mg/m3. The excess
cancer risk related to release of TCE to the ambient air at this
concentration for a 75 year lifetime exposure is estimated to be
1.79 X 10's.

6.3.2.4 Offsite

The only documented emissions within the offsite operable unit is
from the shallow soil. This may be from the volatilization of
groundwater chemicals into ambient air or may represent deposition
in the shallow soil from ambient air. Volatilization of chemicals
from the groundwater was modeled in the BPHE and investigated as
detailed in section 5.2.3.4 above.

Due to the dispersive action of the wind and the low contaminant
concentrations estimated and measured, the risk related to this
exposure pathway in ambient air is nil. The risk from this pathway
was initially estimated based on a two stage model as described
above. Additional risk estimates were made for a maximum and an
average case based on measured, field flux data rather than flux
data estimated by a mathematical transport model. The indoor air
concentration, is still based on a conservative box model that
assumes a low rate of indoor air exchange and a maximal area of
infiltration. The maximum case assumes exposure for 30 years with
the indoor air concentration modeled from the maximum field flux
rate measured. The average case assumes a 9 year exposure with the
indoor air concentration modeled from the mean of the measured
field flux rates. The estimated risk for the maximum case is 5.75
X 10'5 and 9.1 X 10'7 for the average case. In each scenario the only
observed carcinogenic chemical of concern was TCE.

The risk related to the operation of air strippers at the AMD 915
site, where the offsite groundwater is treated, was evaluated after
the completion of the FS. Off gas from the air strippers was

Page 59 of 108
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collected and analyzed for cis-l,2-DCE, trans-l,2-DCE, TCE, 1,1,1-
TCA and vinyl chloride in September 1991. This data was then used
in a screening level model developed by the California Air
Pollution Control Officers Association. This model uses average
area wide meteorological conditions, minimum release point height,
maximum toxicity or carcinogenicity values, and minimum receptor
distances. This model would predict a cancer risk of less than 1
X 10'* and no non-carcinogenic health effects.

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. The
evaluation was not considered separately for the operable units. It
was assumed that the potential for the migration of the
contaminants to a water supply well in the shallow aquifer were
equal.

The evaluation of the this scenario assumes that no further actions
would occur and that the current contaminant concentrations in
groundwater would be present at the time a domestic well began to
draw water from the shallow water bearing zones. This scenario was
evaluated for both the A and B zone waters, but the numbers
presented here are for the A zone which represents the greater risk
and hazard. The non-carcinogenic hazard ratio and the carcinogenic
cancer risk was considered for two cases, the average case and the
maximum case. The average case assumes a 9 year exposure including
ingestion of 1.4 liters of water per day contaminated with the
chemicals of concern as represented by the geometric mean
concentration in data from 1988 through 1989. The maximum case
assumes a *30 year exposure to these chemicals at the maximum
concentration detected in this same database. This scenario assumes
ingestion of 2 liters of contaminated water per day for this 30
year period.

The excess cancer risk for the average or representative case based
on the combination of ingestion and inhalation exposure is 2 X 10'3
(Table 5). The excess cancer risk for the maximum case is 5 X 10'1.
The potential cancer risk was evaluated, under the guidance of EPA
Region IX toxicologist, without the inclusion of 1,1-DCE as a
carcinogen. Under this guidance modified reference dose was used in
the calculation of the hazard ratio for 1,1-DCE. However, based on
guidance from EPA (Risk Assessment Guidance for Superfund), since
the hazard index is greater than one it is not appropriate to
consider 1,1-DCE only as a non-carcinogen since this would require
evaluation of the potential non-carcinogenic effects by target
organ and might not correctly represent the potential carcinogenic
effects of 1,1-DCE. Therefore, the appropriate cancer risk related
to the ingestion of groundwater is 2 X 10'J for the average case and
5 X 10*1 for the maximum case.
Page 60 of 108
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TABLE 5
ADULT CARCINOGENIC RISK
AMD 901/902, SIGNETICS, AND TRW
CHEMICAL

1,1 -OCA .
1,1-DCE
PCE
TCE
VINYL CHLORIDE
TOTAL
TOTAL W/0 1.1 -DCE
CONCENTRATION
M/l
18
9.5
610
560
240

REPRESENTATIVE EXPOSURE
INGESTION
6 X 10*
2 X 10*
2 X 10*
2 X 10*
2 X 10'
2 X 10*
2 X 10 J
INHALATION
NA
4 X 10'
1 X 10'
3 X 10*
2 X 10*
3 X 10*
2 X 10*
TOTAL
6 X 10*
6 X 10*
2.1 X 10*
5 X 10*:
2.2 X 10*
2 X 10'
2 X 10*
CONCENTRATION
M/l
600
63
610
200.000
18,000

MAX 1 HUN EXPOSURE
INCEST ION
6 X 10*
4 X 10*
* X 10*
2 X Iff*
4 X Iff1
* X Iff1
4 x ID'
INHALATION
NA
9 X 10*
2 X 10*
4 X 10*
6 X 10*
1 X Iff1
1 X 10'
TOTAL
6 X 10*
1 X 10*
4 X 10*
6 X 10*
5 X Iff1
5 X Iff1
5 X Iff1
Page 61 of 108
-------
The hazard index for the representative case is greater than one
and is much greater than one for the maximum case. This indicates
that non-carcinogenic health effects would be expected. Since the
hazard index is greater than one the actual health hazard would
require further evaluation on a target organ basis. Since the water
is not currently used as a source of drinking water and is not used
without treatment this was not pursued.

It should be emphasized that the shallow groundwater is not
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 within the study
area.

6.3 PRESENCE OF SENSITIVE HUMAN POPULATIONS

The study area is located in predominantly industrial area however,
the groundwater contamination plume does extend down gradient to the
north, beneath a residential area. The extension of the groundwater
contamination plume North of Duane Avenue (offsite operable unit)
may result in as many as 600 residences overlying the groundwater
plume. This includes the San Miguel School, which currently houses
a daycare center and a Headstart Program.

Since the contaminated groundwater has not affected the drinking
water supply the only possible current exposure is through the
inhalation pathway. This exposure pathway was evaluated for
children attending programs at the San Miguel school facility. The
excess cancer risk for both the average and maximum cases was less
than 1 X 104. The hazard ratio for both the average and maximum
cases was less also less than one. The average case assumed the
children were present for four hours per day for two years. The
maximum case assumed the children were present for eight hours per
day for four years.

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

Page 62 of 108
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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."

6.5 CONCLUSION

Actual or threatened releases of hazardous substances from the
Advanced Micro Devices, 901/902 Thompson Place, Signetics, 811 East
Argues, and former TRW Microwave facility, 825 Stewart Drive
Superfund sites, 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, remedial actions must attain a
degree of clean-up which assures protection of human health and the
environment. Additionally, remedial actions that leave any
hazardous substance, pollutant, or contaminant on-site must meet a
level or standard of control that at least attains standards,
requirements, limitations, or criteria that are "applicable or
relevant and appropriate" under the circumstances of the release.
These requirements, known as "ARARs", may be waived in certain
instances, as stated in Section 121(d)(4) of CERCLA.

"Applicable" requirements are those clean-up standards, standards
of control and other substantive environmental protection
requirements, criteria, or limitations promulgated under federal or
state law that specifically address a hazardous substance,
pollutant or contaminant, remedial action, location, or other
circumstance at a CERCLA site. "Relevant and appropriate" re-
quirements are clean-up standards, standards of control and other
substantive environmental protection requirements, criteria, or
limitations promulgated under federal or state law that, while not
"applicable" to a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstance at a CERCLA site,
address problems or situations sufficiently similar to those
encountered at the CERCLA site that their use is well-suited to the
particular site. For example, requirements may be relevant and
appropriate if they would be "applicable" but for jurisdictional
restrictions associated with the requirement. (See the National
Contingency Plan, 40 C.F.R. Section 300.6, 1986).

The determination of which requirements are "relevant and ap-

Page 63 of 108
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propriate" is somewhat flexible. EPA and the State may look to the
type of remedial actions contemplated, the hazardous substances
present, the waste characteristics, the physical characteristics of
the site, and other appropriate factors. It is possible for only
part of a requirement to be considered relevant and appropriate.
Additionally, only substantive requirements need be followed. If
no ARAR covers a particular, situation, or if an ARAR is not
sufficient to protect human health or the environment, then non-
promulgated standards, criteria, guidance, and advisories must be
used to provide a protective remedy.

7.1 TYPES OF ARARS

There are three types of ARARs. The first type includes
"contaminant specific" requirements. These ARARs set limits on
concentrations of specific hazardous substances, pollutants, and
contaminants in the environment. Examples of this type of ARAR are
ambient water quality criteria and drinking water standards. The
second type of ARAR includes location-specific requirements that
set restrictions on certain types of activities based on site
characteristics. These include restriction on activities in
wetlands, floodplains, and historic sites. The third type of ARAR
includes action-specific requirements. These are technology-based
restrictions which are triggered by the type of action under
consideration. Examples of action-specific ARARs are Resource
Conservation and Recovery Act ("RCRA") regulations for waste
treatment, storage, and disposal.

ARARs must be identified on a site-specific basis from information
about specific chemicals at the site, specific features of the site
location, and actions that are being considered as remedies.

7.2 CONTAMINANT-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
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

Page 64 of 108
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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
ng/1 to approach the 1 in a 1,000,000 excess cancer risk. This is
far below the current MCL for arsenic of 50 /xg/1 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 VOC. This is due to the slow desorption of
VOCs adsorbed to the inner pore spaces of soil particles which make
up the aquifer material and VOCs 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.

7.3 ACTION SPECIFIC ARARS AND TBCS

National Pollutant Discharge Elimination System (NPDES1

NPDES substantive permit requirements and/or RWQCB 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 Emergency Response (OSWER1 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

Page 65 of 108
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Decisions (RODs), Significant Differences to a ROD and Consent
Decrees. The four operable units are 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 precedence over the directive.

Bay Area Air Quality Management District (BAAOMD) 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 chloride, 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 air stripping and soil vapor extraction operations
emitting greater than fifteen pounds per day of organic
compounds other than those listed above are required to
control emissions by at least ninety percent by weight.

Regulation 8, Rule 47 is an ARAR for the implementation of the
remedy at all four operable units.

Bay Area Air Quality ManagementDistrict JBAAQMD)Regulation 8.
Rule 40

Bay Area Air Quality Management District Board of Directors adopted
Regulation 8, Rule 40, July 1986. This rule is entitled "Aeration
of Contaminated Soil and Removal of Underground Storage Tanks". The
purpose of this Rule is to limit the emission of organic compounds
from soil that has been contaminated by organic or petroleum
chemical leaks or spills; to describe an acceptable soil aeration
procedure; and to describe an acceptable procedure for controlling
emissions from underground storage tanks during replacement or
removal. This rule includes standards for aeration, reporting
requirements and a manual of procedures.

o Uncontrolled aeration (8-40-301) is limited by a combination
of organic content and volume.

o Controlled aeration (8-40-302) requires that the emissions of
organic compounds to the atmosphere be reduced by at least 90%
by weight.

Page 66 of 108
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Regulation 8, Rule 40 would be an ARAR for the implementation of
any remedy that includes soil aeration or removal of any soil
containing greater than 50 ppm by weight organic content.

Resource Conservation Recovery Act (RCRA) Land Disposal
Restrictions

The contaminated ground water contains two spent solvents that are
RCRA listed wastes. TCE is an FO01 listed waste, and TCA is an
F002 listed waste. Adsorbents and other materials used for
remediation of groundwater VOCs, such as activated carbon,
chemical-adsorbing resins, or other materials used in'the treatment
of ground water or air will contain the chemicals after use. RCRA
land disposal restrictions are not applicable but are relevant and
appropriate to disposal of treatment media due to the presence of
constituents which are sufficiently similar to RCRA wastes.

Clean Water Act

Under these provisions, discharges of treated groundwater to the
local sanitary sewer must comply with local POTW pretreatment
programs. Discharges of treated groundwater to the sanitary sewer
at AMD 901/902 must meet the substantive standards of the City of
Sunnyvale.

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/Signetics/TRW sites
focuses on the following remedial objectives:

1. Prevention of the near-tern and future exposure of human
receptors to contaminated groundwater and soil;

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

Page 67 of 108
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of cleanup.

8.2 CLEANUP STANDARDS

8.2.1 Cleanup Standards

Even though shallow groundwater affected by these sites is not
currently being used for drinking water, it is a potential drinking
water source and must be protected as such. Therefore, the cleanup
standards have been set at state and federal Maximum Contaminant
Levels (MCLs) for drinking water. The cleanup standards for nine
of the ten chemicals of concern for these sites are the California
MCLs for drinking water (Table 6). The exception is 1,2-DCB for
which California has not established an MCL. The cleanup standard
for 1,2-DCB will be the recently promulgated Federal MCL, which
becomes effective July 1992. Setting the cleanup standards at
these levels fulfills the ARARs and also achieves a risk level
within the EPA acceptable risk range.

For the study area, the carcinogenic risk at the cleanup standards
for all chemicals listed in Table 6 associated with the potential
future use scenario of groundwater ingestion and inhalation of VOCs
from groundwater would be 3.7 X 10-4 (Tables 7 & 8). This risk is
based on all the chemicals in Table 6 being present in the
groundwater any place within the study area. This estimate is based
on assumptions similar to the probable maximum case in the BPHE,
except it assumes a 70 year rather than a 30 year exposure used to
estimate the probable maximum risk scenario in the BPHE.

These assumptions are probably overly conservative, especially the
assumption regarding the occurrence of all chemicals. Table 6 shows
which chemicals occur or would be reasonably expected to occur in
which operable unit. Based on these chemicals only, the estimated
excess carcinogenic risk after cleanup is 6 X 10-6 for the AMD
operable unit and 4 X 10-5 for Signetics, TRW, and the off site
commingled plume (Table 8). In cleaning up TCE to the 5 ppb
cleanup standard it is quite likely that the concentrations of
other VOCs will be reduced to levels below the 5 ppb range. These
risk values represent the maximum residual risk that would be
probable following cleanup.

In addition, these values include 1,1-DCE which is classified by
EPA as a possible human carcinogen. The classification of 1,1-DCE
as a carcinogen is based on a single positive result out of
seventeen studies and, based on guidance of EPA region IX
toxicologist, it is acceptable to exclude 1,1-DCE as a
Page 68 of 108
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TABLE 6
CLEANUP STANDARDS FOR THE CHEMICALS OF CONCERN IN GROUNDWATER

AMD 901/902, Signetics, and TRW
Sunnyvale, California
COMPOUND
1,2- Dichlorobenzene
l,l-Dichloroethanew
l.l-Dichloroethene"
cis-1 ,2-Dichloroethene
trans-l,2-Dichloro-ethene
Freon 113
Tetrachloroethene(c)
1 , 1 , 1 -Trichloroethane
Trichloroethene(e>
Vinyl Chloride'01
FEDERAL MCLGW
^.(fiOO^-
NA
7
(70)
(100)
NA
(0)
200
0
0
FEDERAL HCL*1
(600)
NA
7
(70)
(100)
NA
(5)
200
5
2
CALIFORNIA NCL
NA
5
6
6
10
1,200
5
200
5
0.5
APPLICABLE
OPERABLE UNITS
AMD, TRW
ALL
ALL
ALL
ALL
ALL
AMD, TRW,
OFFSITE
ALL
ALL
AMD, TRW,
Signetics
Shaded criteria are the selected cleanup standards
(a) MCLG = maximum contaminant level goal. Concentrations in micrograms per
liter.
(b) MCL = maximum contaminant level. Concentrations in micrograms per liter.
(c) Potential or probable human carcinogen.
(d) Possible human carcinogen.
NA = Not available.
() Criteria in parentheses, effective July 1992 ,
Page 69 of 108
-------
carcinogen. If 1,1-DCE is not included as a carcinogen, a
modified reference dose is used in the evaluation of the non-
carcinogenic hazard quotient. If it is excluded, the estimated
risk at cleanup standards decreases to 6 X 10-6 for Signetics and
TRW and 3 X 10-6 for the offsite commingled plume.

The non-carcinogenic hazard index at the cleanup standards, for
all of the chemicals shown in Table 6 associated with the
potential future use scenario of groundwater ingestion and
inhalation of VOCs is 0.44 (Table 7). If only those chemicals
that might be reasonable expected to occur within any operable
unit are considered then the hazard index for this scenario is
0.44 for AMD and Signetics operable unit, 0.1 for the TRW
operable unit, and 0.2 for the offsite commingled plume (Table
7).

Cleanup standards for the treated effluent from the air stripper
are set by RWQCB in the NPDES permit process. Cleanup standards
for the air stripper offgas are established by the BAAQMD permit
process. All of the treatment systems, except for the
groundwater treatment system at AMD 901/902, are currently
permitted by the RWQCB and BAAQMD. The groundwater treatment
system at AMD 901/902 does have a permit to operate from the
BAAQMD, however since the water is reused as industrial process
water and indirectly discharged to the sanitary sewer system
apermit from the RWQCB is not required.

Operation of the AMD 901/902 site as a production facility by AMD
will cease sometime in late 1991 or early 1992. This will
preclude the indirect discharge of the treated groundwater under
local POTW regulations. An NPDES permit will be required for
discharge of this water, however the discharge limits have not
been established at this time.

There are currently no ARARs established for cleanup levels in
contaminated soil. However, a RWQCB policy of cleanup to
background or 1 ppm total VOCs for soils is a TBC criteria and
has been set as the soil cleanup standard for these sites.
Experience at other sites has shown that this level will prevent
recontamination of groundwater.

8.2.2 Compliance Boundaries

The compliance boundary for contaminated groundwater includes all
groundwater within the plume boundaries indicated in Figures 16
and 17, all groundwater monitored in existing wells, and any
contaminated groundwater identified by additional monitoring
wells installed upon RWQCB or EPA request for the purpose of
monitoring potential vertical or horizontal migration of the
plumes currently located in the A and B Aquifers.

Page 70 of 108
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No.
1
2
3
4
5
6
7
8
9
to

TABLE 7, HAZARD INDEX AT CLEANUP STANDARDS, AMD 901/902, Siqnetics, TRW
CONCENTRATION (Cu) SET AT ARARs
HAZARD INDEX • CDI/RfO
CM • ARARs.

CDI > Chronic Daily Intake
TBCt. or cleamv BoaU

CHEMICAL
1 ,2-DICHLOROBENZENB
1,1-DCA
1,1-DCE
c!»-l,2-DCE
lnni-l,2-DCE
FREONII3
PCE
1,1,1-TCA
TCE
VINYL CHLORIDE

Cw«/l
0.100
0.005
0.006
0.006
0.010
1.200
0.005
0.200
0.005
0.0005

WOE
MCLVB2
CA MCLVB2
CA MCLVC
CA MCLVD
CA MCLVD
CA MCLVD
MCLVB2
MCLVD
MCLXB2
CA MCLVA

DUS = DUS ORAL REFERENCE DOSE
DWHA - DRINKING WATER HEALTH ADVISORY

ORAL
RfD
0.01
0.100
0.009
0.02
0.02
3
0.01
0.09
NA
NA

CDI
2.86e-03
l.43e-04
l.71e-04
1.7le-04
2.86c-04
3.43e-02
I.43C-04
5.7U-03
1.43e-04
1.43e-05

TOTAL HAZARD INDEX -

WQC - NATIONAL AMBIENT WATER QUALITY CRITERIA FOR PUBLIC
HEALTH
MCL- FEDERAL MCL
CA MCL - CALIFORNIA MCL
WOE - WEIGHT OF EVIDENCE » SOURCE OF DATA
A "KNOWN
HUMAN CARCINOGENS

HI
2.«6e-01
1.43e-03
1.90e-02
».$7e-03
l.43e-02
1.14C-02
1.43c-02
6.35e-02
0.00
0.00

.42eOO

Bl » PROBABLE HUMAN CARCINOGEN (limited human evidence, adequate evidence from animali)
B2 - PROBABLE HUMAN CARCINOGEN (inadequate human evidence, idequate evidence from animals)
C = POSSIBLE HUMAN CARCINOGEN (limited evidence of carcinogenicily, animal studies only)

Inhalation
RfD
NA
0.1
NA
NA
NA
NA
NA
0.3
NA
NA

•

Inhalation
HI
0.00
1.43e-03
0.00
0.00
0.00
0.00
0.00
1.90e-02
0.00
0.00

.20e-01

TOTAL HI
2.S6e-01
2.86e-03
1.90e-02
g.57e-03
1.43e-02
I.14C-02
1.43e-01
S.25e-02
0.00
0.00

.44c+00

"71 nf 10«
-------
TABLE 8, CANCER RISK AT CLEANUP STANDARDS
AMD 901/902, Signet Lea
and TRW
CHEMICAL CONCENTRATION SET TO CLEANUP STANDARDS
DETERMINATION OF EXCESS LIFETIME CANCER RISK FOR
CARCINOGENS
EXCESS LIFETIME CANCER RISK - CDI X q*
q* - CANCER POTENCY FACTOR
(M6/KG/DAY) -1
Cw = ARARs, TBCs, or cleanup goals
CHEMICAL
1,1-DCA
1.1 -OCE
PCE
TCE
VINYL CHLORIDE

WOE » WEIGHT

CwMG/L
0.005
0.006
0.005
0.005
0.0005

UDEXCLASS OF
CARCINOGEN
CA NCL\B2
CA MCL\C
MCL\B2
MCLVB2
CA MCLVA

CDI *• Chronic Daily
Intake (MG/KG)

ORAL q*
9.10e-02
6.00e-01
5.10e-02
1.10e-02
2.30e+00

CDI
1.43e-04
1.71e-M
t.Oe-M
1.43e-M
1.43e-05

EXCESS CANCER RISK
EXCESS CANCER RISK W/0 1.1 -DCE
OF EVIDENCE « SOURCE OF DATA
NCL > FEDERAL DRINKING WATER MAXIMUM CONTAMINANT LEVEL

CAMCL « CALIFORNIA DRINKING WATER MAXIMUM CONTAMINANT LEVEL
A ' KNOWN HUMAN CARCINOGENS

RISK
1.30e-05
1.03e-04
7.29e-06
1.57e-06
3.29e-05

1.58e-M
2.78e-05

B1 • PROBABLE HUMAN CARCINOGEN (United hunen evidence, adequate evidence from animals)

INHALATION q*
HA
1.2045+00
3.30e-03
1.70e-02
2.95e-01

B2 • PROBABLE HUNAN CARCINOGEN (inadeouate hunan evidence, adequate evidence from animals)
C * POSSIBLE
HUMAN CARCINOGEN (United evidence of carcinogeniclty. animal studies only)

INHALATION RISK
0.00
2.06e-04
4.71e-07
2.43e-06
4.21e-06

2.13e-04
7.11e-06

TOTAL
RISK
1.30e-05
3.09e-M
7.76e-06
4.00e-06
3.71e-05

3.71e-04
3.*9«-05

Page 72 of 108
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•- Facility/OU boundaries

— Study Area perimeter
Figure 16. A Zone Plume Boundary at
5 ppb TCE
-------
I I go I
— Facility/OU boundaries

— Study Area perimeter
Figure 17. B Zone Plume Boundary at
5 ppb TCE
-------
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 each Operable Unit and evaluated in detail.

8.3.1 AMD Operable Unit

Approximately 37 cubic yards of residual contaminated soil is
located in the unsaturated zone upgradient of the groundwater
extraction and treatment system. Alternative 1 applies to both
soil and groundwater. Alternatives 2 through 7 specifically
address the soil, and Alternatives 8 through 10 address
groundwater.

AMD 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. No additional soil
remediation would be performed. Groundwater monitoring would
continue. Time for the groundwater to achieve compliance
with ARARs is unknown with best estimates in the range of
hundreds of years. The present worth cost is projected to be
$1.5 million.

AMD Alternative 2; Soil Flushing In this alternative,
water would be percolated through contaminated soil to
solubilize VOCs adsorbed to the soil and flush them into the
groundwater. Groundwater would then be treated by an
activated carbon treatment system. This procedure would
reduce the residual concentrations in the soil and increase
the soluble concentrations in the groundwater. It is
estimated this alternative would take hundreds of years to
reduce concentrations of VOCs in soil to the 1 ppm level.
The present worth cost of this alternative is estimated to
be $2.8 million.

AMD Alternative 3; Soil Aeration This alternative consists
of excavating the contaminated soil and transporting it to
an appropriate treatment area. The soil would be spread out
to a predetermined depth, usually 1 to 3 feet, and
mechanically mixed on a regular basis. The contaminants
would volatilize and be released to the air. Again, it is
estimated this alternative would take hundreds of years to
reduce concentrations of VOCs in soil to the 1 ppm level.
The present worth cost of this alternative is estimated to
be $2.7 million.
Page 75 of 108
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AMD Alternatives 4 through 6: Vaeuu^ Extraction fVE)? VE
with Heated Air Assist; VE with Steam Assist These three
alternatives involve in situ vacuum extraction whereby VOCs
are removed from the soil by mechanically drawing or venting
air through the unsaturated soil layer. The soil would be
gradually treated as the VOCs are released from the soil
particles. Extraction of the VOC-containing vapors could be
enhanced by using heated air or steam. VOC—laden air would
then be treated with an appropriate treatment system.
Again, it is estimated this alternative would take hundreds
of years to reduce concentrations of VOCs in soil to the l
ppm level. The present worth cost of these alternatives
ranges from $2.8 to $3.5 million.•

AMD Alternative 7; Excavation and Offsite
Disposal/Treatment In this alternative, the contaminated
soil would be excavated, the building reinforced as needed,
and the excavation backfilled. The excavated soil would be
treated most likely by incineration and/or disposed offsite.
The concentrations of VOCs in soil can be reduced to the 1
ppm level during the duration of the excavation. The present
worth cost of this alternative is estimated to be $2.7
million.

AMD Alternative 8; Extraction - Air Stripping with Carbon
Adsorption of the Off eras This alternative comprises the
current interim remedial treatment system for the
groundwater (extraction wells, air stripper, and carbon
adsorption of the offgas). Air stripping as a stand—alone
technology is very effective in removing VOCs from
groundwater at the AMD Operable Unit. Carbon adsorption of
the stripper vapor exhaust provides additional treatment.
This alternative is modeled to achieve cleanup standards in
18 years at a present value cost of $2.6 million.

AMD Alternative 9; Extraction - Carbon Adsorption
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 for adsorption of VOCs. Use of the air
stripper would be discontinued. This alternative would not
change the time to achieve ARARs (18 years) however the
present value cost would increase to $4.6 million.

AMD Alternative 10; Augmented Extraction with Enhanced
Treatment This alternative involves installing additional
wells on the AMD OU to extract additional groundwater. The
groundwater would be treated in the existing air stripper
system. An additional carbon adsorption unit would be
installed to provide additional capacity to treat the air
stripper offgas. The increased number of wells would not
result in an increased rate of groundwater extraction,

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therefore the estimated time to achieve ARARs remains at 18
years. The estimated present value cost of this alternative
is $2.8 million.

AMD Treated Groundwater Disposal For all three groundwater
remediation alternatives (8 through 10), discharge options
for treated groundwater include: discharge to a publicly
owned treatment works (POTW), discharge to storm drain, and
industrial process applications. Currently, AMD reuses all
of the treated groundwater in onsite facility uses.

8.3.2 Signetics Operable Unit

Alternatives 1 through 4 combine soil and groundwater remedial
alternatives for the Signetics property.

Sianetics Alternative 1; No Action In this alternative, no
action would be taken to remediate soil or groundwater and
the existing soil—vapor vacuum extraction system would be
shut down. The estimated present value cost of this
alternative is $1.5 million.

Sianetics Alternative 2; No Additional Groundwater or
Vacuum Extraction Alternative 2 comprises the interim
remedial system currently in operation. Groundwater is
extracted using two extraction trenches, six extraction
wells, and three basement dewatering sumps. The existing
soil—vapor vacuum extraction system would continue to
operate. Extracted groundwater would continue to be treated
by air stripping followed by carbon polishing of the
effluent water. In addition, vapor—phase carbon would
continue to be used to remove residual VOCs from the
effluent air stream from the air strippers. The estimated
present value cost of this alternative is $3.9 million.

Sianetics Alternative 3; Enhanced Grouhdwater Extraction
This alternative consists of improving the extraction system
to compensate for declining water levels; these declines
have resulted in decreases in contaminant removal rates and
apparent increases in downgradient VOC concentrations. The
existing soil—vapor vacuum extraction system would continue
to operate. The proposed improvements to the groundwater
extraction system are:

o Increase pumping rate at the 440 Wolfe extraction
trench to decrease the water levels in the trench

o Install a series of A—aquifer extraction wells north of
the 811 Argues Avenue building

o Install piezometers along and north of the 815 Stewart
Drive property boundary to assess the current capture

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zones

o Install additional A—aquifer extraction veils
immediately north of the 815 Stewart building, unless
declining water levels preclude extraction

o Resume pumping from an existing B1/B2—aquifer
extraction well (S—100B1)

o initiate groundwater extraction from the B3—aquifer if
onsite VOC concentrations increase significantly.

The present value cost of this alternative is $3.9 million.

Sianetics Alternative 4; Enhanced Groundwater (A— and
B—Aquifers) and Vacuum Extraction fA—Aquifer) This
alternative is similar to Alternative 3 except that both the
groundwater and vacuum extraction systems are expanded. The
expanded vacuum extraction system would include four
additional vapor extraction wells and an upgrade of the
blowers and carbon adsorption system. The present value cost
of this alternative is $4.1 million.

8.3.3 TRW Operable Unit

Alternatives for remediation of soil have been incorporated into
comprehensive groundwater remediation alternatives for the TRW
property.

TRW Alternative 1; No Action Alternative 1 is a no further
action alternative. All current remedial activities would
be stopped. The present value cost of this alternative is
$1.0 million.

TRW Alternative 2; Current Groundwater Extraction System
With Alternative 2, groundwater extraction from the
7 well/1 eductor system, groundwater treatment by air
stripping, and groundwater discharge under an NPOES permit
would continue. No additional remedial technology would be
required, although the present system would be upgraded as
part of normal maintenance and replacement. This
alternative would also include deed restrictions on the use
of groundwater in the A— and B-aquifers.

The FS estimates that this alternative would require at
least 7 years of operation to reach compliance with
applicable, .relevant, and appropriate requirements (ARARs)
and eleven years to approach non-detect levels of organic
chemicals. The estimated present worth cost of this
alternative is $0.8 million to achieve ARARs and $1.1
million to approach background levels.

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TRW Alternative 3; Soil Flushing and Groundwater
Extraction Alternative 3 combines the components for
Alternative 2 with flushing of source area soils. Soil
flushing should increase water saturation of, and
circulation through, soils, and might increase the potential
for VOC desorption from soils to groundwater, thus reducing
the time for VOC removal from the subsurface soil.

The FS estimates that this alternative would require at
least* 7 years of operation to reach compliance with ARARs
and eleven years to approach non-detect levels of organic
chemicals. The estimated present worth cost of .this
alternative is $0.8 million to achieve ARARs and $1.2
million to approach background levels.

TRW Alternative 4; Partial Excavation and Groundwater
Extraction Alternative 4 consists of excavating the most
highly contaminated soils north and west of the former tank
area, dewatering the entire excavated area, and backfilling
the excavation with clean material. This alternative would
also include deed restrictions on the use of groundwater in
the A— and B—aquifers and continued pumping, treatment, and
discharge of groundwater from existing and two new
extraction wells. This alternative would require
significant engineering controls prior to and during
excavation, as well as relocation of operational equipment.

The FS estimates that this alternative would require at
least 7 years of operation to reach compliance with ARARs
and eleven years to approach non-detect levels of organic
chemicals. The estimated present worth cost of this
alternative is $1.6 million to achieve ARARs and $2 million
to approach background levels.

8.3.4 Offsite Operable Unit

Remedial alternatives for soil were not addressed for the Offsite
OU because contaminant sources in soil are limited to the
facility properties.

Offsite Alternative l; No Action The no action alternative
involves no further action to treat, contain, or remove any
of the contaminated groundwater. To implement this
alternative, planned and existing remedial measures would be
discontinued. Groundwater monitoring would continue. Time
for the groundwater to achieve compliance with ARARs is
unknown with best estimates in the range of hundreds of
years. The present worth cost is projected to be $1.9
million.
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Offsite Alternative 2; Expanded Extraction. Air Stripping,
and Carbon Adsorption; This alternative consists of
continued operation of the existing offsite extraction and
treatment system. The system currently extracts groundwater
from 23 extraction wells. The extracted groundwater is
conveyed through an underground piping system to the
AMD Building 915 treatment facility; the groundwater is
treated by air stripping followed by aqueous carbon
adsorption. Currently, about 30% of the treated groundwater
is reused at the AMD facility, with the remainder discharged
under NPDES permit CA0028797 to the storm drain system. The
spent carbon is removed and regenerated offsite as needed,
approximately every 1.5 years.

The hydraulic performance evaluation of the extraction
system indicated that because of declining water levels,
hydraulic capture is not being fully maintained in the A-
and B2—aquifers. It is estimated that 5 new A—aquifer
extraction wells (or an extraction trench) and 3 new
B2—aquifer wells may be needed to maintain adequate
capture. Based on results of a simplified model it is
estimated that this alternative could meet groundwater ARARs
in 36 years. The present worth cost for this alternative is
estimated at $4.4 million. ,

Offsite Alternative 3t Extraction and Carbon Adsorption
This alternative consists of pumping groundwater from the
upgraded offsite extraction systems and treatment of the
water by carbon adsorption. The treated groundwater would
be reused and/or discharged under NPDES permit CA0028797 to
the storm drain system. This alternative differs from
Alternative 2 in that VOC removal is accomplished by means .
of a carbon adsorption unit only, rather than by use of a
combined air stripping/carbon adsorption system. The
estimated time to achieve cleanup is 36 years, the same as
Alternative 2. The present worth cost for this alternative
. is estimated at $10 million. ;

9.0 COMPARATIVE ANALYSIS OF ALTERNATIVES

This section provides an explanation of the nine criteria used to
select the remedy, and an analysis of the remedial action
alternatives in light of these criteria, highlighting the
advantages and disadvantages of each alternative.

9.1 NINE CRITERIA

The alternatives were evaluated using nine component criteria.
These criteria, which are listed below, are derived from require-
ments contained in the National Contingency Plan (NCP) and CERCLA
Sections 121(b) and 121(c).

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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.

6. Implementability.

7. State acceptance/Support Agency acceptance.

8. Community acceptance.

9. Cost.

9.2 ANALYSIS OF ALTERNATIVES

The analysis for two of the nine criteria, State acceptance and
Community acceptance, generally apply equally to all of the
alternatives. Their analysis will be provided at the beginning
of this section.

STATE ACCEPTANCE AND COMMUNITY ACCEPTANCE

The Feasibility Study and the Proposed Plan Fact Sheet were
reviewed by the RWQCB and they concur with EPA's preferred
alternatives, thus providing State acceptance. Based on
questions raised by the community and discussed in the
Responsiveness Summary (Appendix A), there appears to be
community acceptance for the selected remedies in so far as the
remedies address the groundwater and soil at the AMD, Signetics,
and TRW properties.

There is significant community concern about the potential for
VOCs to volatilize from the offsite groundwater and then migrate
through the soil gas and eventually become concentrated in
confined spaces of buildings in the residential -area.
Groundwater extraction that proceeds as rapidly as possible is
the selected remedy at all of the sites and addresses this
potential volatilization problem by reducing the concentrations
of contaminants in the groundwater, which, in turn, reduces the
potential for significant levels of VOCs to reach buildings at
the surface. Actual field measurements of the vapor flux at the
soil surface have not indicated a significant problem. Field
measurements will continue and a reassessment of the problem will
be initiated at the 5 year review period, unless the need for

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earlier reassessment is indicated by future field measurements.

At this time, EPA and RHQCB do not believe that selection of an
additional remedial action (e.g., ventilation aids placed in
buildings) will be necessary. For the time being, the community
appears to have accepted this strategy for addressing the
potential volatilization problem.

9.2.1 AMD Operable Unit

Of the ten alternatives evaluated for the cleanup of the AMD
property, Alternatives 2 through 7 specifically address the
contaminated soil. Alternatives 8 through 10 specifically
address the contaminated groundwater. Alternative 1 is the no
action alternative for both the soil and the ground water.

9.2.1.1 AMD Soils

AMD Soil: PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

Alternatives 5, 6, and 7 are protective of human health and the
environment because they remove the soil contaminants from the
site either by enhanced vacuum extraction or excavation followed
by offsite treatment and disposal. Only Alternative 7 is
protective in a reasonable time frame. Alternatives 5 and 6
would require hundreds of years to reach the cleanup standard of
1 ppm total VOCs because of the physical properties of some
chemicals of concern, notably DCB and PCE, that make their
removal from soil extremely difficult. Upon implementation,
Alternative 7 will immediately prevent the soil from acting as a
further source of groundwater contamination and will prevent soil
contaminants from volatilizing into the soil gas and eventually
migrating into confined spaces of dwellings at the surface.

Without the advantages of heated air or steam assistance
(Alternatives 5 and 6), the vacuum extraction of Alternative 4
would not be effective enough to eliminate the risk from PCE and
DCB. As is the case with Alternatives 4, 5, and 6, Alternative 3
depends on the transfer of chemicals from the soil to vapor. PCE
and DCB are bound too tightly to the soil to be effectively
removed by simple aeration. In addition, the time to reach the
cleanup standards for offsite disposal of the extracted soils in
Alternative 3 would require hundreds of years. Similar physical
chemical properties of PCE and DCB prevent Alternative 2 from
effectively removing these contaminants from the soil by using
soil flushing as a form of enhanced groundwater treatment.

Alternative 1 is not protective of human health and the
environment because it would leave all VOC contaminants in place
in the soil.
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AMD Soil: COMPLIANCE WITH ARARS

Alternative 7 is the only soil remediation alternative that will
comply with all pertinent ARARs identified in Section 7 in a
reasonable amount of time. It would comply with the RCRA land
disposal restriction by first treating the excavated soil offsite
with an appropriate technology before disposal. The current
treatment technology for removal of the majority of VOCs in soil
is incineration, which would result in permanent destruction of
the chemicals of concern. The actual treatment technology will
be determined by LDRs at the time of removal.

Due to the difficulty in implementation of Alternative 7, AMD
will be given up to two years from the adoption of the RWQCB
Order (June 1991) to complete the Alternative 7 soil remedy. All
other alternatives would not comply with soil ARARs for hundreds
of years.

Alternatives 3 through 6 involve air emissions that come under
regulation by BAAQMD. Emissions from the vapor extraction
alternatives would comply with air ARARs, but Alternative 3
emissions from onsite soil aeration may not meet BAAQMD
requirements. Alternative 3 would attain the UIC ARAR for
injected water.

Because of the difficulty in removing DCB and PCE from soil under
native conditions, compliance with TBCs is questionable for all
of the Alternatives except Alternative 7 due to the length of
time required to reach the soil cleanup criteria of 1 ppm.
Heated air or steam injection (Alternatives 5 and 6) may enhance
the removal rates, however neither is a proven technology and the
same physical limits may still apply. Alternative 7 would
achieve the soil cleanup criteria by removing all soil that
contains above 1 ppm total VOCs.

Alternatives 3 and 7 would also be required to comply with BAAQMD
Rule 8, Regulation 40.

AMD Soil: REDUCTION OF TOXICITY. MOBILITY. OR VOLUME OF
CONTAMINANTS THROUGH TREATMENT

Alternative 7 provides the greatest reduction in toxicity
mobility and volume of soil contaminants through excavation
followed by contaminant destruction from an incineration
technology. All other treatment alternatives do not affect the
toxicity of the soil contaminants, but they do reduce their
mobility and volume in the soil.

Like Alternative 7, Alternative 3 reduces soil contaminant
mobility by excavation. Unlike Alternative 7, the mobility and
volume of the contaminants then increases as aeration of the
soils emits the contaminants into the air.

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Air emissions from the vapor extraction remedies would be
controlled by adsorption of the contaminants .onto vapor-phase
carbon. Regeneration of the carbon by an incineration technology
would destroy the contaminants, thus providing the maximum
reduction in toxicity, mobility, and volume for those
contaminants removed from the soil. Because of physical and
chemical limitations, it would require hundreds of years to
remove enough contaminants from the soils by vapor extraction or
aeration to reduce the total VOCs down to 1 ppm.

Alternative 1 provides no reduction in toxicity, mobility, or
volume. .

AMD Soil: LONG-TERM EFFECTIVENESS AND PERMANENCE

Alternative 7 provides the best long-term effectiveness of
all the alternatives for soil cleanup because the soil
contaminants are removed from the site and eventually destroyed
at an offsite treatment and disposal facility. Removal will
prevent the soil from acting as a further source of groundwater
contamination and will prevent soil contaminants from
volatilizing into the soil gas and eventually migrating into
confined spaces of dwellings at the surface.

Alternative 3 is a reliable way of eliminating the soil as a
source of groundwater contamination, although it would leave
contaminants onsite during the aeration process. However, the
time to reach the cleanup standard for offsite disposal is
estimated to be hundreds of years. This is a function of the
physical properties of some chemicals of concern, notably DCB and
PCE, that makes their removal from soil difficult.

Alternatives 4 through 6 are all dependent upon the transfer of
chemicals from soil to vapor, as is Alternative 3. Alternative 4
would not effectively remove PCE or DCE. Alternatives 5 and 6
are evolving technologies and pilot tests at the site would be
needed to determine their effectiveness. They would remove
volatile contaminants but might leave elevated levels of DCB in
the soil.

Vapor exhaust for Alternatives 4 through 6 would be controlled by
carbon adsorption which is an adequate and reliable technology.

Contaminant residues on the carbon would be destroyed during
regeneration of the carbon by an incineration technology.

Alternative 2, soil flushing, would take an excessively long time
to reach the proposed cleanup level of 1 ppm for total VOCs. This
is exacerbated by the low solubilities of some of the chemicals
.of concern, particularly DCB.

Alternative 1 provides no long-term effectiveness.

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AMD Soil: SHORT-TERM EFFECTIVENESS

Alternatives 1 and 2 do not increase the risk to the community
because downgradient monitoring would alert the community to
possible VOC migration to leading edge wells. The plume would
continue to migrate under Alternative l.

Alternatives 4 through 6 would cause a minor increased risk
exposure to workers during the construction activities necessary
to install the vapor extraction system.

Alternatives 3 and 7 involve soil excavation which would increase
the chances of exposure of workers and the community to
contaminated dust and volatilized contaminants in the air near
the site.

Due to the difficulty in implementation of Alternative 7, AMD
will be given up to two years from the adoption of the RWQCB
Order (June 1991) to complete the soil remedy. This possible
delay is still protective of human health and the environment on
the short-term because/ at this time, the majority of soil in
question is protected from infiltrating surface water by
concrete. This soil is also prevented from coming into direct
contact with the water table by operation of the AMD 901
groundwater extraction system. This extraction system also
controls the migration of contaminated water from the site. This
alternative can achieve Board guidance of 1 ppm total VOCs
immediately upon completion of the removal action.

AMD Soil: IMPLEMENTABILITY

Alternative 1 would be easiest to implement since it requires no
action.

Treatment Alternatives 4 through 6 would be easiest to implement
because they involve in situ technologies. Alternatives 5 and 6
might be slightly more difficult to implement than Alternative 4
because they represent evolving variations of simple vacuum
extraction and pilot tests would be necessary. Permit
requirements can be readily attained.

Alternatives 3 and 7 are not easily implemented because they
would require that operations in the building be temporarily
halted, and adequate construction controls (including dust
minimization) would be needed. Due to the difficulty in
implementation, AMD will be given up to two years from the
adoption of the RWQCB Order (June 1991) to complete the soil
remedy. Permit requirements should be readily attained.
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Like Alternative 7, Alternative 3 is not easily implemented
because it will require that operations in the building be
temporarily halted, and adequate construction controls (including
dust minimization) would be needed. It is unlikely that BAAQMD
permit requirements could be met.

Alternative 2 would be very difficult to implement because
reinjection of the groundwater would be required. The clay soil
structure at this site would tend to channel the injected water
and, thus -it may not be possible to implement soil flushing
effectively.

AMD Soil: COST

The FS provided cost figures for the soil remedies as if
groundwater monitoring and groundwater extraction and treatment
would continue for 18 years without any changes to the present
system at AMD 901. The 18-year present worth cost of these
groundwater activities is $2.6 million based on an annual O&M of
$225,000. The following discussion of costs for soil remedies
has subtracted out the groundwater costs since they are dealt
with in the analysis of groundwater remedies for AMD 901 in
Section 9.2.1.2.

Alternative 1 would leave the soil in place without any treatment
or other action. It thus has no costs associated with the soil
portion of the Alternative. Groundwater monitoring would
continue and the associated costs are discussed with the
groundwater remedies.

The least expensive soil remedies involve excavation and either
offsite treatment and disposal (Alternative 7) or onsite
treatment and disposal (Alternative^). While Alternative 3 has
a lower capital cost of $27,000 compared to $47,000 for
Alternative 7, the $6,000 annual O&M cost makes Alternative 3
twice as expensive as Alternative 7, which has no O&M costs. The
18-year present worth costs of Alternatives 3 and 7 are $96,000
and $47,000, respectively. Alternative 7 is the most cost
effective of all the treatment alternatives.

Alternatives 2 and 4 have nearly identical present worth costs
at, $224,000 and $225,000, respectively. Like Alternative 3,
neither of these two alternatives is effective enough to
adequately address the contaminated soil. Alternative 2 has a
capital cost of $86,000 and an annual O&M cost of $12,000, while
Alternative 4 has a capital cost of $63,000 and an annual O&M
cost of $14,000.

The most expensive alternatives involve enhancements of the pure
vacuum extraction offered in Alternative 4. The hot air assist
in Alternative 5 and the steam assist in Alternative 6 have
present worth costs of $327,000 and $943,000, respectively.

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Alternative 5 has a capital cost of $73,000 and an annual O&M
cost of $22,000. The capital cost and annual O&M cost for
Alternative 6 are $122,000 and $71,000, respectively. The cost
estimates for these alternatives are based on 18 years of o&M,
although effective cleanup of the soils by these alternatives
would take much longer than 18 years.

9.2.1.2 AMD Groundwater

AMD GW: PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

Alternatives 8, 9, and 10 basically provide equal protection of
human health and the environment because they both extract
groundwater that contains contaminants at concentrations above
drinking water standards and capture the contaminants on either
vapor-phase or liquid-phase carbon followed by their destruction
during carbon regeneration. Extraction prevents further
migration of the plume. Deed restrictions protect against use of
the aquifers before cleanup is completed. After cleanup, these
alternatives are estimated to result in a reduced cancer risk
range, as discussed in Section 8.2.1, of 3.7 X 10"* to 6 X 10"* and
a reduced HI of 0.44. All treated water is reused before
ultimate discharge to the sanitary sewer.

Air emissions from Alternatives 8 and 10 are considered
sufficiently protective since they meet BAAQMD permit .
requirements while the calculated worst case cancer risk is 1.6 X
10^ and the HI is less than 1.

Alternative 1 provides little reduction of risk since natural
attenuation of groundwater contaminant concentrations could
require more than 100 years compared to the approximately 18 year
cleanup time for Alternatives 8, 9 and 10. While future use of
the contaminated groundwater may be unlikely, a future user of
the contaminated groundwater would be exposed to a cancer risk of
5 X 10*1 and an HI much greater than 1. . Finally, Alternative l is
least protective of human health and the environment because it
does not include deed restrictions and thus, greatly increases
the chances that an individual will install a well into a
migrating plume.

AMD GW: COMPLIANCE WITH ARARS ,
•M^AMM^h^^b^MB^MMBd^^M^BK^^^^MMA^BArtXM^MMHMM ^ ^

Alternatives 8, 9 and 10 would attain all pertinent ARARS iden-
tified in Section 7. The Safe Drinking Water Act MCLs and
California Department of Health Services DWALs would be achieved
by extracting groundwater contaminated above these levels. The
Fish and Wildlife Coordination Act would not be an ARAR for these
alternatives 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

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protective of human health and the environment.

The RCRA land disposal restrictions would apply to the spent car-
bon from Alternative 8, 9 and 10. The spent carbon would be
treated before reuse or disposal by an incineration process.

Only Alternatives 8 and 10 would need to comply with OSWER
Directive 9355.0-28 and BAAQMD Regulation 8, Rule 47 because of
the air stripper emissions. These ARARs are addressed by the
BAAQMD permitting process, and the air strippers have emissions
control.

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 Guadelupe Slough and other tributary streams and
marshes. California's resolution 68-16 would not be achieved
since the groundwater contaminants would unreasonably affect the
present and potential uses of the upper aquifers. RCRA land
disposal restrictions, BAAQMD Regulation 8, and OSWER Directive
9355.0-28 would not apply to Alternative 1 since it does not use
treatment.

AMD GW: REDUCTION OF TOXICITY. MOBILITY. OR VOLUME OF
CONTAMINANTS THROUGH TREATMENT

Alternatives 8, 9 and 10 reduce the toxicity, mobility, and
volume of groundwater contaminants by removing greater than 99%
of the contaminants from the extracted groundwater. They
concentrate the contaminants onto granular activated carbon,
which would then be regenerated or properly disposed at a
landfill. Contaminants could potentially be destroyed during
carbon regeneration, making any future release of the removed
contaminants impossible.

Alternative 1 does not reduce toxicity, mobility, or volume since
the groundwater contaminants are allowed to continue migrating.

AMD GW: LONG-TERM EFFECTIVENESS AND PERMANENCE

Alternatives 8, 9 and 10 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

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residences is addressed by the groundwater extraction system in
Alternatives 8, 9 and 10. Groundwater extraction reduces the
amounts of contaminants that could volatilize into the soil gas
and eventually into surface air. Furthermore, deed restrictions
will prevent the installation of wells in the on-site portion of
the plume until it is cleaned up. Finally, this newly recognized
potential problem will be much better understood by the time the
first five-year review occurs. Fans or other active or passive
ventilation aids could be provided to any affected buildings in
addition to continuation of deed restrictions.

Treatment by air stripping provided by Alternatives '8 and 10 is
reliable for the long-term removal of VOCs from the groundwater.
Treatment residuals are expected to be negligible based on the
high volatility of the compounds present in the groundwater and
their capture by the vapor-phase carbon after air stripping.

Treatment by aqueous phase granular activated carbon provided by
Alternative 9 is reliable for the removal of VOCs from the
groundwater. 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. If vinyl chloride is
produced as a degradation product from TCE or DCE, it will not be
effectively trapped on the carbon employed in any of the
treatment alternatives.
Alternative 1 provides no long-term effectiveness.

AMD GW: SHORT-TERM EFFECTIVENESS

The short-term impact to the health of workers and the community
will be very minimal for Alternatives 8, 9 and 10 because the
groundwater extraction system is already in place as the interim
remedial action at the site. There would be no current addi-
tional risks since the plume is already contained and the treat-
ments are protective. Groundwater cleanup time is estimated to
require about 18 years.

Alternative 1 does not include the implementation of treatment
remedies; therefore, there are no additional risks to the
community. Risks associated with the contaminant plume would
remain at the site for over 100 years until natural attenuation
reduces the contaminant concentrations down to the cleanup stan-
dards .

AMD GW: IMPLEMENTABILITY

Alternatives 8 and 9 include the same extraction system which is
already in place. Alternative 10 would augment the extraction
system by the installation of additional extraction wells and

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emissions-control carbon canisters. These alternatives provide
groundvater treatment with either an air stripper or carbon
adsorption. Both methods are proven technologies and there are
no technical considerations that prohibit the use of either of
these technologies. In addition, these alternatives are
administratively feasible using existing permits for air
emissions.

Alternative 8 is the easiest to implement since it is already
implemented as the interim remedy at the site. Alternatives 9
and 10 would require modifications to the present extraction
and/or treatment system, but their implementation would still be
relatively easy. Institutional controls required in Alternatives
8, 9, and 10 are administratively feasible.

There are no technical concerns regarding the implementability of
Alternative 1.

AMD GW: COST

Based on an estimated 18 years to cleanup the A Aquifer and 9
years for the B Aquifer, costs of Alternatives 8, 9 and 10 are
significantly greater than the 30 years of groundwater monitoring
in Alternative 1. Alternative 8 is the most cost effective since
it will meet all cleanup requirements for a present worth cost of
2.6 million dollars compared to the 2.8 million dollar present
worth cost of Alternative 10 and the 4.6 million dollar present
worth cost of Alternative 9. Alternative 1 has a present worth
cost of 1.5 million dollars, but would be ineffective for
cleanup.

Alternatives 1 and 8 have no capital costs while Alternatives 9
and 10 have capital costs of 37 and 53 thousand dollars,
respectively.

The annual O&M costs for Alternatives 8 and 10 are nearly
identical at 225 and 239 thousand dollars, respectively. The
large amount of carbon for Alternative 9 gives it an annual O&M
cost of 382 thousand dollars. Alternative 1 represents the
annual cost of groundwater monitoring at 100 thousand dollars.

9.2.2 Signetics Operable Unit

Signetics: 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
groundwater that contains contaminants at concentrations above
drinking water standards, they all extract contaminants from soil
gas using vapor extraction, and they all capture the contaminants
on vapor-phase carbon followed by contaminant destruction during

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carbon regeneration. Groundwater extraction prevents further
migration of the plume. Deed restrictions protect against use of
the aquifers before cleanup is completed. After cleanup, as
discussed in Section 8.2.1, these alternatives are estimated to
result in a reduced cancer risk range of 3.7 X 10 "* to 6 X 10"6
and a reduced HI of 0.44. All treated water is reused before
ultimate discharge to the sanitary sewer or irrigated landscape.

Air emissions from Alternatives 2, 3 and 4 are considered
sufficiently protective since they meet BAAQMD permit
requirements while the calculated worst case cancer risk is 1.5
X 10*6 and the HI is less than 1. Air stripper emissions are
greatly reduced by the vapor-phase carbon control units.
Emissions from the soil vapor extraction system are captured by
carbon control units. Emissions to ambient air are essentially
nil and do meet BAAQMD requirements

Alternative 1 provides little reduction of risk since natural
attenuation of groundwater contaminant concentrations could
require more than 100 years compared to the approximately 24-36
year cleanup time for Alternatives 2, 3 and 4. While future use
of the contaminated groundwater may be unlikely, a future user of
the contaminated groundwater would be exposed to a cancer risk of
5 X 10'1 and an HI much greater than 1. Finally, Alternative 1 is
least protective of human health and the environment because it
does not include deed restrictions and thus, greatly increases
the chances that an individual will install a well into a
migrating plume.

Signetics: COMPLIANCE WITH ARARS

Alternatives 2, 3 and 4 would attain all pertinent ARARS iden-
tified in Section 7. The Safe Drinking Water Act MCLs and
California Department of Health Services DWALs would be achieved
by extracting groundwater contaminated above these levels. The
Fish and Wildlife Coordination Act' would not be an ARAR for these
alternatives 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 car-
bon from Alternative 2, 3 and 4. The spent carbon would be
treated before reuse or disposal by an incineration process.

Alternatives 2, 3 and 4 would need to comply with OSWER Directive
9355.0-28 and BAAQMD Regulation 8, Rule 47 because of the air
stripper emissions. These ARARs are addressed by the BAAQMD per-
mitting process and the air strippers have emissions control.

The drinking water ARARS would not be attained by Alternative 1

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since contamination would be left in place. The Fish and
Wildlife Coordination Act would become an ARAR if the plume
migrated to Guadelupe Slough and other tributary streams and
marshes. California's resolution 68-16 would not be achieved
since the groundwater contaminants would unreasonably affect the
present and potential uses of the upper aquifers. RCRA land
disposal restrictions, BAAQMD Regulation 8, and OSWER Directive
9355.0-28 would not apply to Alternative 1 -since it does not use
treatment.

Signetics: REDUCTION OF TOXICITY. MOBILITY. OR VOLUME OF
CONTAMINANTS THROUGH TREATMENT

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 groundwater. They concentrate
the contaminants onto granular activated carbon, which would then
be regenerated or properly disposed at a landfill. Contaminants
could potentially be destroyed during carbon regeneration, making
any future release of the removed contaminants impossible.

Alternative 1 does not reduce toxicity, mobility, or volume since
the groundwater contaminants are allowed to continue migrating.

Signetics: 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 and soil
vapor extraction systems in Alternatives 2, 3 and 4. These
extractions reduce the amount of contaminants that could
volatilize into the soil gas and eventually into surface air.
Furthermore, deed restrictions will prevent the installation of
wells in the on-site portion of the plume until it is cleaned up.
Finally, this newly recognized potential problem will be much
better understood by the time the first five-year review occurs.
Fans, other ventilation aids, or passive ventilation aids could
be provided to any affected buildings in addition to the above
deed restrictions.

Treatment by air stripping provided by Alternatives 2, 3 and 4 is
reliable for the long-term removal of VOCs from the groundwater.

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Treatment residuals are expected to be negligible based on the
high volatility of the compounds present in the groundwater and
their capture by the vapor-phase carbon after air stripping. If
vinyl chloride is produced as a degradation product from TCE or
DCE, it will not be effectively trapped on the carbon employed in
any of the treatment alternatives.

Alternative 1 provides no long-term effectiveness.

Signetics: SHORT-TERM EFFECTIVENESS

The short-term impact to the health of workers and the community
will be very minimal for Alternative 2 because the groundwater
extraction and soil vapor extraction systems are already in place
as the interim remedial action at the site. Alternatives 3 and 4
would involve the installation of some additional wells at only a
very minor risk from drilling activities to the drillers. For
all of these alternatives 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 24-36 years.

Signetics: IMPLEMENTABILITY

Alternative 2 includes the same extraction system which is
already in place. Alternatives 3 and 4 would augment the
extraction system by the installation of additional extraction
wells and emissions-control carbon canisters. These alternatives
provide groundwater treatment with an air stripper followed by
vapor-phase carbon adsorption. Both methods are proven
technologies and there are no technical considerations that
prohibit the use of either of these technologies. In addition,
these alternatives are administratively feasible using existing
permits for air emissions.

Alternative 2 is the easiest to implement since 'it is already
implemented as the interim remedy at the site. Alternatives 3
and 4 would require modifications to the present extraction
system, but their implementation would still be relatively easy.
Institutional controls required in Alternatives 2, 3, and 4 are
administratively feasible.

There are no technical concerns regarding the implementability of
Alternative 1.
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Signetics: COST

Based on an estimated 13 years to cleanup the A Aquifer and 36
years for the B Aquifer using Alternative 2 and based on an
estimated 8 years to cleanup the A Aquifer and 24 years for the B
Aquifer using Alternatives 3 or 4, total costs for treatment
alternatives are significantly greater than the 30 years of cost
for groundwater monitoring in Alternative 1. Alternative 4 is
the most cost effective since it will most rapidly meet all
cleanup requirements for a present worth cost of 4.1 million
dollars compared to the 3.9 million dollar present worth costs of
Alternatives 2 and 3. Essentially, the additional 0;2 million
dollar cost of Alternative 4 supports the accelerated remediation
of hot spots. Alternative 1 has a present worth cost of 1.5
million dollars, but would be ineffective for cleanup.

Alternatives 1 and 2 have no capital costs while Alternatives 3
and 4 have capital costs of 252 and 351 thousand dollars,
respectively.

The annual O&M costs for Alternatives 2, 3, and 4 are nearly
identical at 236, 236 and 246 thousand dollars, respectively.
Alternative 1 represents the annual cost of groundwater
monitoring at 95 thousand dollars.

9.2.3 TRW Operable Unit

TRW: PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

Alternatives 2, 3 and 4 are protective of human health and the
environment to roughly the same degree because they extract
groundwater 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, as
discussed in Section 8.2.1, all three alternatives are estimated
to result in a reduced cancer risk range of 3.7 X 1CT* to 6 X 10"6
and a reduced HI range of 0.44 to 0.1 related to domestic use of
groundwater. Any un-recycled treated effluent would meet NPDES
discharge requirements which are protective of human health and
the environment.

Alternatives 3 and 4, which take a more active role in addressing
the contaminated soil in the saturated A Zone, would not provide
significantly greater protection of human health and the
environment since the location of the contaminated soil is
downgradient from contaminated groundwater at the AMD 901/902
property and would likely be recontaminated until the upgradient
contamination is cleaned up.

Alternatives 2,3 and 4 all would use air-stripping to treat the

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extracted groundwater. The use of an air-stripper is considered
to be sufficiently protective since it does satisfy BAAQMD
requirements which is the appropriate ARAR and would result in an
estimated increased cancer risk of about 1.79 X 10'5.

Alternative 1 provides no reduction in risk because it allows the
contaminated groundwater to continue migrating. Natural
attenuation of the groundwater contaminant concentrations could
require more than 100 years compared to the approximately 7 year
cleanup time for the other alternatives. While future use of the
contaminated groundwater may be unlikely, a future user of the
contaminated groundwater would be exposed to a maximum cancer
risk of 5 X 10'1 and an HI much greater than 1. Alternative 1 is
thus the least protective of human health and the environment.

TRW: COMPLIANCE WITH ARARS

Alternatives 2, 3 and 4 would attain all pertinent ARARS
identified in Section 7. The Safe Drinking Water Act MCLs and
the California Department of Health Services DWALs would be
achieved in approximately 7 years by extracting groundwater
contaminated above these levels. NPDES permit requirements would
be met by proper design and operation of the treatment system.
Closure requirements would be met by achieving MCLs in the
groundwater. The Fish and Wildlife Coordination Act would not be
an ARAR for these three alternatives because the groundwater
extraction system would prevent the plume from reaching surface
waters or wet lands and the treatment system would ensure that
any discharged water was protective of human health and the
environment.

The RCRA land disposal restrictions would apply to the spent
carbon from Alternatives 2, 3 and 4 in the event that it became
necessary to implement air stripper emissions control involving
gas-phase activated carbon. The spent carbon could be treated
before reuse or disposal by an incineration process.

Alternatives 2, 3 and 4 would need to comply with OSWER Directive
9355.0-28 and BAAQMD Regulation 8 Rule 47 because of the air
stripper emissions. These ARARS are addressed by the BAAQMD
permitting process. If permit modifications become necessary,
emissions could be captured and destroyed by available
technology. Alternative 4 might also be required to comply with
mass emission standards in BAAQMD Rule 40, Regulation 8.

Alternative 1 would not comply with drinking water ARARS for at
least 100 years since contamination would be free to migrate.
The Fish and Wildlife Coordination Act would become an ARAR if
the plume migrated to a surface water or other tributary streams
and marshes. California's resolution.68-16 would not be achieved
since the groundwater contaminants would unreasonably affect the

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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 it does not use treatment.

TRW: REDUCTION OF TOXICITY. MOBILITY. OR VOLUME OF
CONTAMINANTS THROUGH TREATMENT

Alternatives 2, 3 and 4 reduce the toxicity, mobility, and volume
(TMV) of groundwater contaminants by removing greater than 99% of
the contaminants from the extracted groundwater. However, these
alternatives transfer the groundwater contaminants to the 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 BAAQMD
permit that does not require emissions control.

Alternative 3 may provide slightly less reduction in VOC mobility
because possible loss of complete hydraulic control as a result
of soil flushing may increase the mobility of the VOCs.
Alternative 4 may provide slightly greater reduction in TMV if
the small volume of extracted soil is treated with a destructive
technology prior to disposal. Alternative 1 provides no
reduction in TMV.

TRW: LONG-TERM EFFECTIVENESS AND PERMANENCE

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 that proceeds as
rapidly as possible addresses this potential volatilization
problem by reducing the concentrations of contaminants in the
groundwater, which, in turn, reduces the potential for
significant levels of VOCs to reach buildings at the surface.
Actual field measurements of the vapor flux at the soil surface
have not indicated a significant problem. Field measurements
will continue and a reassessment of the problem will be initiated
at the 5 year review period, unless the need for earlier
reassessment is indicated by future field measurements. Fans or

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other ventilation aids could be provided to any affected
buildings. Furthermore, deed restrictions will prevent the
installation of wells in the onsite portion of the plume until it
is cleaned up.

Treatment by air stripping provided by Alternatives 2, 3, and 4
is reliable for the long-term removal of VOCs from the
groundvater. Treatment residuals are expected to be negligible
based on the high volatility of the compounds present in the
groundvater.

Alternative 1 would provide long-term effectiveness -after more
than 100 years that would be necessary for natural attenuation.
Offsite monitoring may not be reliable for detecting further
downgradient migration. Alternative 1 provides very little long-
term effectiveness in comparison to the other three alternatives.

TRW: SHORT-TERM EFFECTIVENESS

The short-term impact to the health of workers and the community
will be very minimal for the groundwater portion of Alternatives
2, 3 and 4 because the extraction and treatment 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
is estimated to require about 7 years.

Alternative 4 is slightly less effective on the short-term than
Alternatives 2 and 3 because of the increased dust containing
VOCs and VOC emissions during excavation of the small volume of
contaminated soil in the saturated zone.

Alternative 1 doesn't include the implementation of a treatment
remedy; therefore, there are no additional risks to the
community. Risks associated with the contaminant plume would
remain at the site for over 100 years until natural attenuation
reduces the contaminant concentrations down to the cleanup
standards.

TRW: IMPLEMENTABILITY

Alternatives 2, 3 and 4 are easily implemented for the
groundwater extraction and treatment system since it is already
implemented with the required permits in place. Additional
permits would be required for soil flushing in Alternative 3, but
should be readily obtainable. Institutional controls required
in Alternatives 2, 3 and 4 are administratively feasible.

Excavation is a proven technology, however excavation near a
building poses severe logistical problems for FEI Microwave, the
current occupants of the TRW onsite area. This significantly
lowers the implementability of the soil portion of Alternative 4.

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In Alternatives 2 and 3, the soil is addressed by the groundwater
extraction and treatment system. There are no technical concerns
regarding the implementability of Alternative 1.

TRW: COST

Alternatives 2 and 3 have nearly identical costs. Alternative 2
is slightly less expensive with a present worth cost of $750,379
compared to $827,379 for Alternative 3. Due to the difficulty of
the soil excavation near a building,. Alternative 4 is
dramatically more expensive with a present worth cost of 1.6
million dollars. Alternative 1 is the second most expensive
alternative because groundwater monitoring would be needed well
beyond the 7 year cleanup time estimated for the other
alternatives. For a 30 year monitoring period, the present worth
cost would be $984,893.

9.2.4 Offsite Operable Unit

Offsite: PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

Alternatives 2 and 3 basically provide equal protection of human
health and the environment because they both extract groundwater
that contains contaminants at concentrations above drinking water
standards. Extraction prevents further migration of the plume
and continually reduces the contaminant concentrations, thus
continually decreasing the potential for volatilized VOCs to
reach significant concentrations inside surface dwellings. After
cleanup, as discussed in Section 8.2.1, both Alternatives 2 and 3
are estimated to result in a reduced cancer risk range of 3.7 X
10-"°3 X 10-6 and a reduced HI range of 0.44 to 0.2. Water
discharged or reused following treatment would meet NPDES
requirements which are protective of human health and the
environment.

Alternative 3 could be considered slightly more protective than
Alternative 2 since it would not involve the transfer of
groundwater contaminants to the air and would involve the
destruction of the contaminants by regeneration of the granular
activated carbon. Air emissions from Alternative 2 are
considered sufficiently protective, however, since they meet
BAAQMD permit requirements, while the calculated worst case
cancer risk less than 1 X 10'5 and the HI is less than 1.

Alternative 1 provides far less reduction in risk because it
would allow the contaminated groundwater to. continue migrating
and natural attenuation of groundwater contaminant concentrations
could require more than 100 years compared to the approximately
36 year cleanup time for Alternatives 2 and 3. While future use
of the contaminated groundwater may be unlikely, a future user of
the contaminated groundwater would be exposed to a cancer risk of

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5 X 10'1 and an HI much greater than l. Alternative 1 is least
protective of human health and the environment, because it does
not include deed restrictions, and thus greatly increases the
chances that an individual will install a well into a migrating
plume.

Offsite: COMPLIANCE WITH ARARS

Both Alternatives 2 and 3 would attain all pertinent ARARS iden-
tified in Section 7. The Safe Drinking Hater Act MCLs and
California Department of Health Services DWALs would be achieved
by extracting groundwater contaminated 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 and 3 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 car-
bon from Alternative 3 and would also 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 could be treated before reuse or disposal by an in-
cineration process.

Only Alternative 2 would need to comply with OSWER Directive
9355.0-28 and BAAQMD Regulation 8, Rule 47 because of the air
stripper emissions. These ARARs are addressed by the BAAQMD per-
mitting process. If permit modifications become necessary, emis-
sions could 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 for at least 100
years. The Fish and Wildlife Coordination Act would become an
ARAR if the plume migrated to Guadelupe Slough and other
tributary streams and marshes. California's resolution 68-16
would not be achieved since the groundwater contaminants would
unreasonably 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 it does not use treatment.

Offsite: REDUCTION OF TOXICITY. MOBILITY. OR VOLUME OF
CONTAMINANTS THROUGH TREATMENT

Both Alternatives 2 and 3 reduce the toxicity, mobility, and
volume of groundwater contaminants by removing greater than 99%
of the contaminants from the extracted groundwater. Alternative
3 concentrates the contaminants onto granular activated carbon,

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which would then be regenerated or properly disposed at a
landfill. Contaminants could potentially be destroyed during
carbon regeneration, making any future release of the removed
contaminants impossible. . . ,

Alternative 2 transfers the groundwater contaminants to the 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 BAAQMO
permit that does not require emissions control. A.very tiny
fraction of the groundwater contaminants will be captured on the
carbon polisher and would be destroyed during regeneration or
treated before disposal at a proper landfill.

Alternative 1 does not reduce toxicity, mobility, or volume of
the groundwater contaminants because they are allowed to continue
migrating. '

Offsite: LONG-TERM EFFECTIVENESS AND PERMANENCE

Alternatives 2 and 3 include groundwater extraction which is in*
tended 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 and 3. Groundwater extraction reduces the amounts
of contaminants that could volatilize into the soil gas and even-
tually into surface air. The RWQCB has required the PRPs to
continue measuring soil vapor emissions from selected points
along a plume cross-section on a semi-annual basis for at least
two years. This newly recognized potential problem will be much
better understood by the time the first five-year review occurs.
If necessary, more refined air sampling could be conducted at
that time. Fans or other ventilation aids could be provided to
any affected buildings.

Treatment by air stripping provided in Alternative 2 is reliable
for the long-term removal of VOCs from the groundwater. , Treat-
ment residuals are expected to be negligible based on the high
volatility of the compounds present in the groundwater.

Treatment by aqueous phase granular activated carbon provided in
Alternative 3 is reliable for the removal of VOCs from the ,
groundwater. Treatment residuals are expected to be negligible

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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.

Offsite: SHORT-TERM EFFECTIVENESS

The short-term impact to the health of workers and the community
will be very minimal for Alternatives 2 and 3 because the
groundwater extraction system is already in place as the interim
remedial action at the site. There would be no current addi-
tional risks since the plume is already contained and the treat-
ments are protective. Groundwater cleanup time is estimated to
require about 36 years. Uncontrolled air emissions from Alterna-
tive 2 make it slightly less effective in protecting health and
the environment than Alternative 3 in the short-term.

Offsite: IMPLEMENTABILITY

Alternatives 2 and 3 include the same extraction system which is
already in place. Both alternatives provide groundwater treat-
ment with either an air stripper or carbon adsorption. Both
methods are proven technologies and there are no technical con-
siderations that prohibit the use of either of these tech-
nologies. In addition, both alternatives are administratively
feasible using existing permits for discharge or air emissions.

Institutional1 controls required in Alternatives 2 and 3, are
administratively feasible. There are no technical concerns
regarding the implementability of Alternative 1.

Offsite: COST

Based on an estimated 21 years to cleanup the A Aquifer and 36
years for the B Aquifer, costs of Alternatives 2 and 3 are
significantly greater than the 30 years of groundwater monitoring
in Alternative 1. Alternative 2 is the most cost effective since
it will meet all cleanup requirements for a present worth cost of
4.4 million dollars compared to the 10 million dollar present
worth cost of Alternative 3. Alternative 1 has a present worth
cost of 1.9 million dollars, but would be ineffective for
cleanup.

The annual O&M costs for Alternatives 1, 2, and 3 are 124, 255,

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and 637 thousand dollars, respectively. The capital cost of
Alternatives 1, 2, and 3 are 56, 208, and 411 thousand dollars,
respectively.

9.3 THE SELECTED REMEDY

9.3.1 Basis of Selection

The selected remedies addressing contaminated groundwater all
basically entail the continuation of the current IRM, groundvater
extraction followed by air stripping. In some cases, minor
modifications will be made in the form of additional extraction
wells and increased water reuse. These remedies met all of the
nine criteria and adequately addressed the remedial action
objectives. Implementability and cost effectiveness
distinguished these alternatives from other alternatives that
also met the nine criteria and remedial action objectives. The
selected remedies are relatively easy to implement and, in most
cases, easier to implement than competing alternatives. Except
for the Signetics remedy, the selected remedies were the least
expensive of the competing alternatives and always the most cost
effective. The Signetics remedy costs 0.2 million dollars more
than its two competing alternatives, but is more cost effective
because the accelerated hot spot remediation increases the
overall effectiveness of the groundwater cleanup.

Remedies and alternatives with either liquid-phase or vapor-phase
carbon treatment are advantageous because they involve the
destruction of the adsorbed VOCs during carbon regeneration, thus
providing the maximum reduction in toxicity, mobility, and
volume. Liquid-phase carbon treatment was evaluated as an
alternative for the AMD onsite unit, but it was not selected
because the existing air stripper remedy contains equally
effective vapor-phase carbon emission control at half the present
worth cost. Only the TRW onsite and the offsite commingled plume
air strippers do not contain GAC air emission control.

Despite the slight advantages in contaminant destruction offered
by the carbon treatment alternative for the offsite commingled
plume, the existing air stripper without emissions controls was
selected because of several advantages. These advantages include
the fact that the air stripper costs less than carbon adsorption
and is already installed 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 permit modifications become necessary.
This last point is also true of the TRW air stripper remedy,
which was selected without comparison to a liquid-phase carbon
treatment alternative.

The relatively small volume of contaminated soil in the saturated
zone at TRW is best addressed by the present groundwater

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extraction and treatment system. The two alternatives that were
not selected as the remedy are either dramatically more expensive
and difficult to implement or not significantly more effective.

For AMD soils, the selected remedy is excavation followed by
offsite treatment (incineration) and disposal. While some of the
in situ alternatives are easier to implement, the selected remedy
is the only alternative that will meet ARARs in a reasonable
amount of time. It is also the most cost effective alternative
and involves destruction of the contaminants, thus providing the
greatest reduction in toxicity, mobility, and volume.

9.3.2 Features of the Remedies

The groundwater remedies selected for each of the
AMD/Signetics/TRW sites involve institutional controls, continued
groundwater monitoring, and continued groundwater extraction and
treatment with the air strippers that are currently in place.
Existing NPOES permitted discharge of treated water to Calabazas
Creek and existing BAAQMD permitted air emissions will continue.
Basically, these remedies are already implemented and operating
with acceptance form the community and federal, state, and local
agencies. In some cases, minor modifications will be made in the
form of additional extraction wells and increased water reuse.
The total combined cost for the remedies has a present worth of
12 million dollars. The features of these remedies are described
below along with specific soil remedies for some of the sites.

1. Institutional Controls

Deed and well-permit restrictions will protect humans from
exposure to contaminated groundwater below the AMD, Signetics,
and TRW properties during the cleanup period.'

2. Groundwater Monitoring

Continued groundwater monitoring and soil flux monitoring will
verify plume containment, determine current plume boundaries,
follow the decrease in VOC concentrations as the cleanup
progresses, and verify compliance with RWQCB orders.

3. Groundwater Extraction

Continued groundwater extraction from a total of 19 A Aquifer
wells, 2 extraction trenches and multiple building dewatering
sumps which extract from the A zone and 23 B Aquifer wells
distribute a total flow of approximately 225 gpm among four
different treatment system locations. Existing and new well
locations and pumping rates contain the plume and will prevent
further migration of the VOC-contaminated groundwater. The
cancer risk of 5 X 10'1 for a future use of drinking water

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contaminated with vinyl chloride, TCE and DCE will be
continually reduced over an estimated 36-year cleanup period
to a maximum risk of 3.7 X 10"*. Thus, groundwater extraction
until drinking water standards are achieved will attain ARARs
and permanently restore the contaminated aquifers to their
maximum beneficial uses.

Enhanced groundwater extraction at the Signetics property will
focus on two areas: improved control of contaminant migration
laterally in the A zone and, improved control of vertical
migration of contaminants from the Bl and B2 zones to B3 and
B4 zones. The enhancement may include modificatipn of existing
equipment, installation of new wells or trenches and increased
rates of groundwater withdrawal from the deeper aquifers.

Modification of the Alvarado and Duane Avenue offsite
extraction systems and continued groundwater extraction from
these modified systems would focus on improving control of the
A zone plume under the current drought conditions.

4. Air Stripping

Existing air strippers will remove more than 99% of the VOCs
from the extracted groundwater. In addition, air stripper
effluents from the Signetics property and the offsite
commingled plume are polished with liquid-phase carbon. These
treatments allow the effluent to be either reused or
discharged under existing NPDES permits to Calabazas creek
without degrading this surface water or presenting a
significant risk to human health and the environment.

The AMD and Signetics property air strippers contain vapor-
phase carbon to control air emissions, while the TRW and
offsite strippers do not currently contain emissions control.
Emissions from the air strippers are considered safe by the
BAAQMD under existing permits. The TRW and offsite strippers
will include air emissions control if emissions exceed levels
permitted by the BAAQMD.

The spent carbon from the liquid and vapor phase control units
is transferred to a licensed facility where it is regenerated
by thjiwjrof a rotary kiln. Thus, a significant amount of
the VOCi^inre ultimately destroyed, further reducing the
mobility, and volume of the original contamination.

5. Water Reuse

Currently, more than 50% of the treated effluents are reused
as process makeup water, cooling tower water, irrigation, or
other uses. This percentage will increase dramatically as
reuse of effluent from the offsite air stripper located at AMD

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915 increases from 35% to 65% by the end of 1991. The
required goal is 100% reuse of the 150 to 200 gpm treated
effluent at AMD/Signetics/TRW as soon as possible.

6. Soil Remediation

The 37 cubic yards of contaminated soil at the AMD property .
will be excavated and transported offsite for treatment and
disposal. The treatment will likely involve an incineration
technology resulting in destruction of the VOC contaminants.
This remedy prevents human exposure to the contaminants and
prevents recontamination of the groundwater.

The existing soil vapor extraction system at the Signetics
property will be enhanced by increasing the number of vapor
extraction wells and the volume of vapor-phase carbon units
for emissions control.

There is no current exposure pathway for the small volume of
contaminated soils at the TRW site. These soils will be
decontaminated by natural soil flushing. The resulting
contaminated groundwater will be captured and treated by the
current groundwater extraction and treatment system.

9.3.3 Uncertainty in the Remedy

The groundwater remediation remedy for each of the
AMD/Signetics/TRW sites involves groundwater extraction followed
by treatment with air strippers. The goal of this remedial
action is to restore the ground water to its beneficial use,
which is, at these sites, a potential source of drinking water.
Based on information obtained during the RI and on a careful
analysis of all remedial alternatives, EPA and the RWQCB believe
that the selected remedy will achieve this goal. It may become
apparent, during implementation or operation of the groundwater
extraction 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.

The selected remedy will include groundwater extraction for an
estimated period of 12 to 38 years, during which the system1s
performance will be carefully monitored on a regular basis and
adjusted as warranted by the performance data collected during
operation. Modifications may include any or all of the
following:

a) at individual wells where cleanup goals have been attained,
pumping may be discontinued;

b) alternating pumping at wells to eliminate stagnation points;

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c) pulse pumping to allow aquifer equilibration and to allow
adsorbed contaminants to partition into ground water; and

d) installation of additional extraction wells to facilitate or
accelerate cleanup of the contaminant plume.

To ensure that cleanup goals continue to be maintained, the
aquifer will be monitored at those wells where pumping has ceased
on an occurrence of every 5 years following discontinuation of
groundwater extraction.

10.0 STATUTORY DETERMINATIONS

The selected remedies will comply with Section 121 of CERCLA.
The selected remedies protect human health and the environment
through extraction and treatment of the VOC-contaminated ground
water and the removal of contaminated soils. The reductions in
risk are summarized in Section 9.3.2 of this ROD. There are no
short-term or long-term threats associated with the selected
remedies that cannot be readily controlled. In addition, no
adverse cross-media affects are expected from the remedies.

The selected remedies will comply with all of the identified
chemical, 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 particular groundwater remedy may be reevaluated.

The present worth cost of the selected remedies total $11.9
million dollars for the AMD/Signetics/TRW sites. This total is
the sum of $2.65 million for AMD onsite, $4.11 million for
Signetics onsite, $0.75 million for TRW onsite, and $4.39 million
for the offsite commingled plume. These remedies are the least
costly of the alternatives which are equally protective of human
health and the environment. The selected remedies are already
installed for the most part and are operating in accordance with
current permits for water discharge and air emissions.

The selected remedies use permanent solutions and alternative
treatment: (oit resource recovery) technologies to the maximum ex-
tent pra«;i|$able and satisfy the statutory preference for
remedie*@||pif£.employ treatment that reduces toxicity, mobility,
or volune^ptir principal element. In addition, the remaining
toxicity^mobility, and volume of contaminants emitted from the
TRW onsite and the offsite commingled plume air strippers could
be potentially captured and destroyed by available emissions
control technology if permit modifications become necessary.
Section 9.3.2 of this ROD summarizes the key features of the
selected remedies.

Because the remedies will result in hazardous substances

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remaining onsite 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 actions to ensure that the remedies continue to provide
adequate protection of human health and the environment.

11.0 DOCUMENTATION OF SIGNIFICANT CHANGES

There were, no significant changes between the proposed plan and
this Record of Decision.

PART III. RESPONSIVENESS SUMMARY

1.0 INTRODUCTION

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)
and 915 DeGuigne Drive (AMD 915), the former TRW Microwave at 825
Stewart Drive (TRW) the Signetics facility at 811 E. Argues, all
in Sunnyvale. A single responsiveness summary was prepared for
this group of 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 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
comment during this period was 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

Since RWQCB is the lead agency for AMD 901/902, Signetics, and
TRW Microwave 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

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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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