Fifth Five Year Review Report - Records Collections

FIFTH FIVE-YEAR REVIEW REPORT FOR

SYNERTEK, INC. (BUILDING 1) SUPERFUND SITE

SANTA CLARA, CALIFORNIA

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PREPARED BYU.S. Army Corps of Engineers

Seattle DistrictFOR

U.S. Environmental Protection Agency, Region IXand

California Regional Water Quality Control Board San Francisco Bay Region

Richard Hiett, Acting Assistant DirectorCalifornia Site Cleanup and Enforcement BranchU.S. Environmenta’ Psotection Agency, Region 9L)IgItaIIy signe’cI

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~_Date:~9i 7.09.2711 :37:4c5 -0700

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Approved by: Date:

Stephen Hill, ChiefToxics Cleanup DivisionCalifornia Regional Water Quality Control Board San Francisco Bay Region

[This page is intentionally left blank.]

Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site iii

Executive Summary

This is the fifth Five-Year Review of the Synertek, Inc. (Building 1) Superfund Site (Site) located in

Santa Clara, California. The purpose of this Five-Year Review is to review information to determine if

the remedy is, and will continue to be, protective of human health and the environment.

The Site is approximately 1.5 acres and is located at 3050 Coronado Drive in Santa Clara, California.

The Site overlies the Santa Clara Valley groundwater basin. In 1982, the Regional Water Quality

Control Board (RWQCB) and Honeywell, the current owner of the Site, discovered contamination in

groundwater at the Site. It was later determined that the contamination originated from an on-site

solvent tank and three neutralization tanks. The contaminants found included trichloroethene (TCE),

1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichlorethene (1,1-DCE), 1,1-dichlorothane (1,1-DCA), 1,2-

DCA, vinyl chloride, and Freon 113.

On June 28, 1991, the Environmental Protection Agency (EPA) along with the Regional Water

Quality Control Board (RWQCB) selected a groundwater extraction and treatment (GWET) system

using air stripping as the remedy for the Site. The Remedial Action Objectives (RAOs) of the remedy

are: prevent exposure of human receptors to contaminated groundwater, restore contaminated

groundwater for future use as potential drinking water, control contaminant migration, and monitor

contaminant levels in groundwater.

Additional elements from the 1991 Record of Decision (ROD) include periodic groundwater

monitoring, institutional controls, and a conduit investigation. The GWET system began operation in

1987, and was shut down in 2001 with RWQCB concurrence after extraction rates declined such that

continued operation of the GWET provided little benefit. Semi-annual groundwater monitoring

continues at the Site.

Since shutdown, there have not been significant changes in size of the plume, location, or

concentration of contaminants; however, ROD groundwater clean-up standards have not been met. In

2004, Honeywell implemented an MNA trial program at the Site to determine if MNA was a viable

approach to achieve the ROD clean-up standards. From 2011 to 2013, Honeywell completed an

Enhanced In-Situ Bioremediation (EISB) pilot test. On September 30, 2013, Honeywell submitted a

Focused Feasibility Study to the RWQCB including the results of the EISB pilot test.

The exposure assumptions remain the same, as there have been no physical changes or changes in use

for the Site. The site is achieving three RAOs; preventing exposure of human receptors to

contaminated groundwater, control of contaminant migration, and groundwater monitoring. However,

the site is not achieving the objective of restoration of groundwater as a potential drinking water

source. Since the ROD states that a GWET system will restore the water and because the Site will not

reach this RAO with a GWET system, an alternative to the selected remedy is required. To help

achieve selection of an alternate remedy a Focused Feasibility Study was completed and is under

review.

iv Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site

The remedy at Synertek, Inc. (Building 1) Superfund Site is currently protective of human health and

the environment because institutional controls are preventing exposure. However, for the remedy to

be protective in the long-term, a new remedy needs to be selected since the groundwater extraction and

treatment system is no longer operating.

Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site v

Contents

Executive Summary ............................................................................................................ iii

List of Figures...................................................................................................................... vi

List of Tables ....................................................................................................................... vi

List of Abbreviations .......................................................................................................... vii

1. Introduction ................................................................................................................... 8

1.1. Background ............................................................................................................10

1.2. Physical Characteristics .........................................................................................10

1.3. Hydrology ...............................................................................................................11

2. Remedial Actions Summary ....................................................................................... 12

2.1. Basis for Taking Action ...........................................................................................12

2.2. Remedy Selection ..................................................................................................12

2.3. Remedy Implementation ........................................................................................13

2.4. Operation and Maintenance (O&M) ........................................................................14

3. Progress Since the Last Five-Year Review ................................................................ 14

3.1. Previous Five-Year Review Protectiveness Statement and Issues .........................14

3.2. Work Completed at the Site During this Five-Year Review Period ..........................16

4. Five-Year Review Process .......................................................................................... 16

4.1. Community Notification and Site Interviews ............................................................16

4.2. Data Review ...........................................................................................................17

4.2.1. Ground Water..................................................................................................17

4.2.2. Vapor Intrusion ................................................................................................21

4.3. Site Inspection ........................................................................................................21

5. Technical Assessment ................................................................................................ 21

5.1. Question A: Is the remedy functioning as intended by the decision documents? ....21

5.2. Question B: Are the exposure assumptions, toxicity data, clean-up levels, and

remedial action objectives (RAOs) used at the time of remedy selection still valid? ..........22

5.3. Question C: Has any other information come to light that could call into question the

protectiveness of the remedy? ..........................................................................................22

6. Issues/Recommendations .......................................................................................... 22

7. Protectiveness Statement ........................................................................................... 23

8. Next Review ................................................................................................................. 23

Appendix A: Site Chronology ............................................................................................ 24

vi Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site

Appendix B: List of Documents Reviewed ...................................................................... 26

Appendix C: Supplemental Data Information .................................................................. 27

Appendix D: ARAR Assessment ...................................................................................... 32

Appendix E: Contaminants of Concern ........................................................................... 35

Appendix F: Toxicity Analysis .......................................................................................... 36

Appendix G: Interview Forms ........................................................................................... 39

Appendix H: Site Inspection Checklist Photographs from Site Inspection Visit ........... 42

Appendix J: Public Notice ................................................................................................. 68

List of Figures

Figure 1. Location Map for the Synertek, Inc. (Building 1) Superfund Site ........................... 11

Figure 2. TCE Distribution in Aquifer Zone A ...................................................................... 18

Figure 3. TCE Distribution in Aquifer Zone B ....................................................................... 20

List of Tables

Table 1. Five-Year Review Summary Form ........................................................................... 9

Table 2. Clean-up Standards from 1991 Record of Decision ............................................... 13

Table 3. Summary of Planned and/or Implemented Institutional Controls ............................ 14

Table 4. Status of Recommendations from the 2012 Five-Year Review .............................. 15

Table 5. Issues and Recommendations Identified in the Five-Year Review ......................... 22

Table 6. Protectiveness Statement ...................................................................................... 23

Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site vii

List of Abbreviations

ARARs Applicable or Relevant and Appropriate Requirements

bgs below ground surface

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

COC contaminant of concern

DCA dichloroethane

DCE dichloroethene

EISB enhanced in situ bioremediation

FFS focused feasibility study

GWET groundwater extraction and treatment

MCL Maximum Contaminant Level

μg/L micrograms per liter

MNA monitored natural attenuation

NPDES National Pollutant Discharge Elimination System

NPL National Priorities List

O&M operation and maintenance

RAOs Remedial Action Objectives

ROD Record of Decision

RWQCB Regional Water Quality Control Board

TCA trichloroethane

TCE trichloroethene

EPA United States Environmental Protection Agency

USACE United States Army Corps of Engineers

VI vapor intrusion

VOC volatile organic compound

8 Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site

1. Introduction

The purpose of a Five-Year Review (FYR) is to evaluate the implementation and performance of a

remedy to determine if the remedy is and will continue to be protective of human health and the

environment. The methods, findings, and conclusions of reviews are documented in Five-Year Review

reports. In addition, Five-Year Review reports identify issues found during the review, if any, and

document recommendations to address them.

The U.S. Environmental Protection Agency (EPA) is preparing this Five-Year Review pursuant to the

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 121, 40

Code of Federal Regulation (CFR) Section 300.430(f)(4)(ii) of the National Contingency Plan (NCP) and

EPA policy.

This report is the fifth Five-Year Review for the Synertek, Inc. (Building 1) Superfund Site (Site). The

triggering action for this statutory review is the completion date of the previous Five-Year Review. The

Five-Year Review has been prepared because hazardous substances, pollutants, or contaminants remain at

the site at levels above those that would allow for unlimited use and unrestricted exposure. The

groundwater remedy was implemented in accordance with the Record of Decision (ROD), dated June 28,

1991.

The Synertek, Inc. (Building 1) Superfund Site Five-Year Review was led by David Barr, California

Regional Water Quality Control Board (RWQCB). Participants included Peter Gibson, remediation

biologist with the U.S. Army Corps of Engineers (USACE); Benino McKenna, geologist with USACE;

Jacob Williams, chemist with USACE; and Melanie Morash and Angela Sandoval, Remedial Project

Managers with EPA. The review began on November 9, 2016.

Fifth Five-Year Review for Synertek, Inc. (Building 1) Superfund Site 9

Table 1. Five-Year Review Summary Form

SITE IDENTIFICATION

Site Name: Synertek, Inc. (Building 1)

EPA ID: CAD0990832735

Region: 9 State: CA City/County: Santa Clara/Santa Clara

SITE STATUS

NPL Status: Final

Multiple OUs?No Has the site achieved construction completion? Yes

REVIEW STATUS

Lead agency: State (California Regional Water Quality Control Board)

Author name (Federal or State Project Manager): David Barr, Water Resource Control Engineer &

Melanie Morash, Remedial Project Manager

Author affiliation: California Regional Water Quality Control Board & Environmental Protection

Agency

Review period: 11/9/2016 - 9/28/2017

Date of site inspection: 1/26/2017

Type of review: Policy

Review number: 5

Triggering action date: 9/28/2012

Due date (five years after triggering action date): 9/28/2017


1.1. Background

The Site is located at 3050 Coronado Drive in the city of Santa Clara, California, and covers

approximately 1.5 acres. Santa Clara has a population of approximately 120,000 and is considered part of

the San Francisco Bay metropolitan region.

In 1982, the RWQCB discovered solvent contamination in groundwater at the Site in groundwater

samples collected as part of a leak detection program for underground tanks. This discovery initiated a

remedial investigation, which identified the source of contamination as leaks from on-site solvent and

neutralization tanks. In 1985, Honeywell Inc., the successor company to Synertek, Inc., removed these

tanks and the surrounding impacted soil.

1.2. Physical Characteristics

The Site is in a light industrial and commercial area. Most buildings in the area are low rise developments

containing office space and research and development facilities. The Site consists of a low rise building

with adjacent parking and landscaping areas.

The Site area land use was agricultural until 1974, at which point it began transforming into commercial

and industrial use. In 1974, Synertek leased the site for semiconductor manufacturing and constructed

Building 1, located at 3050 Coronado Drive. Beginning in 1978, the building was used for performing

quality control of chemicals and electrical testing of semiconductors. In 1979, Honeywell acquired

Synertek. Synertek manufacturing operations ceased in 1985 and the building remained vacant until

1989. Currently, Building 1 is leased to Crystal Solar which uses the southern two-thirds of the building

(approximately 16,000 square feet) as office space and for research and development of solar panels.

Other various organizations occupy the remaining parts of the building.


Figure 1. Location Map for the Synertek, Inc. (Building 1) Superfund Site

1.3. Hydrology

The Site location is the Santa Clara Valley, a structural basin filled with coarse and fine grained marine

and alluvial sediment deposits. These deposits form a complex series of discontinuous aquifers and

aquitards at the Site extending from approximately 10 feet below ground surface (bgs) to a thick relatively

impermeable aquitard at a depth of approximately 171 feet bgs. Municipal water supply wells in the area

are screened beneath this aquitard in the confined regional aquifer approximately 200 to 300 feet bgs.

The Site hydrology includes three distinct shallow water bearing zones: Aquifer Zone A, found from 10

feet bgs to 20 feet bgs; Aquifer Zone B, found from about 30 to 50 feet bgs; and Aquifer Zone B1, found

between 100 and 108 feet bgs. The B-aquifer is underlain by approximately 60 feet of clay, which

effectively separates it from the B1-aquifer. The nearest municipal water supply well is located

downgradient, approximately 1.6 miles north of the Site.


2. Remedial Actions Summary

2.1. Basis for Taking Action

The Site overlies the Santa Clara Valley groundwater basin, which in 1989 provided nearly half of the

drinking water supply for 1.4 million residents. The Synertek Site was placed on the National Priorities

List (NPL) primarily because of the past chemical releases’ potential threat to this valuable resource.

2.2. Remedy Selection

Prior to selection of the remedy, Honeywell removed two underground tank systems east of Building 1

and affected soils in 1985 as part of an interim remedial measure, under the RWQCB oversight.

Honeywell also began operating a groundwater extraction and treatment (GWET) system in 1987 to

address the VOC contamination identified in the groundwater when the tanks were removed.

The EPA selected remedy was issued on June 28, 1991, with the following remedial action objectives

(RAOs):

• Prevention of the near-term and future exposure of human receptors to contaminated

groundwater;

• Restoration of the contaminated groundwater for future use as potential drinking water;

• Control of contaminant migration; and

• Monitoring of contaminant concentrations in the ground water.

Major components of the remedy selected in the 1991 ROD include:

• A deed restriction prohibiting the use of shallow groundwater;

• Periodic groundwater monitoring;

• Groundwater extraction and treatment (GWET) with air stripping;

• discharge of the treated groundwater to the storm drain under an NPDES permit; and

• Search for and seal the remaining agricultural well that is believed to exist near the plume.

The groundwater clean-up values are based on EPA MCLs, or CA MCLs, except for clean-up levels for

acetone and xylenes (both risk-based), and toluene (CA Action Level). The clean-up standards for the

Site are presented in Table 2; standards apply to all on-site and off-site wells.


Table 2. Clean-up Standards from 1991 Record of Decision

Chemical

Clean-up

Standard (μg/L)*

Basis for Clean-up

Standard

acetone 350 Risk1

benzene 1 CA MCL2

bis(2-ethylhexyl)phthalate 4 CA MCL

1,1-dichloroethane (1,1-DCA) 5 CA MCL

1,1-dichloroethene (1,1-DCE) 6 CA MCL

cis-1,2-dichloroethene (cis-1,2-DCE) 6 CA MCL

ethylbenzene 680 CA MCL

Freon-113 1200 CA MCL

styrene 5 EPA MCL PR3

toluene 100 CA AL4

1,1,1-trichloroethane (1,1,1-TCA) 200 CA MCL

trichloroethene (TCE) 5 CA MCL

vinyl chloride 0.5 CA MCL

xylenes 175 Risk5

*micrograms per liter (μg/L) 1. / Clean-up standard for acetone set an order of magnitude lower than the level that would contribute a value of 1.0

to the cumulative non-carcinogenic risk (Total Hazard Index). 2. / California Maximum Contaminant Level for drinking water (CA MCL). 3. / Proposed EPA Maximum Contaminant Level for drinking water (EPA MCL PR). 4. / California Department of Health Services Action Level (CA AL). 5. / Clean-up standard for xylenes set an order of magnitude below CA MCL of 1750 µg/L to reduce its contribution

to the cumulative non-carcinogenic risk from 0.6 to 0.0.

2.3. Remedy Implementation

The groundwater extraction and treatment (GWET) system and groundwater monitoring program were

already implemented at the time ROD was adopted. Construction of the GWET was documented as

complete in March 25, 1992, with the signing of the Preliminary Closeout Report. In September 2000,

the Water Board and Honeywell jointly evaluated continued operation of the GWET. Based on the

findings of this joint evaluation, it was determined that the continued operation of the GWET was not

warranted. Operation of the GWET had reduced the average concentration of TCE in the A- and B-

aquifers by 93 and 99 percent, respectively. At that time, groundwater monitoring data indicated that

VOC concentrations in monitoring wells and treatment system influent were approaching asymptotic

levels, suggesting that further reduction of VOCs in groundwater using the GWET would not be feasible.

Groundwater was extracted and treated until January 2001, at which time the Regional Board approved

the shutdown of the GWET system with continued groundwater monitoring. At the time of the shutdown,

the GWET system had removed a total of 84 pounds of VOCs. Honeywell proposed a monitored natural

attenuation (MNA) investigation to evaluate the effects of discontinuing operation of the GWET and the

feasibility of implementing MNA as a method for controlling the migration of VOCs in groundwater and

remediating the VOC plume at the site.


The remedy also included groundwater monitoring and institutional controls (IC) to prevent the

installation of ground water wells, groundwater use, or activities that could endanger public health.

Additionally, Honeywell completed the potential conduit investigation, but without finding the

agricultural well that was believed to exist.

Table 3. Summary of Planned and/or Implemented Institutional Controls

Media, engineered

controls, and areas

that do not support

for unlimited use and

unrestricted

exposure based on

current conditions

ICs

Needed

ICs Called

for in the

Decision

Documents

Impacted

Parcel(s)

IC

Objective

Title of IC

Instrument

Implemente

d and Date

(or planned)

Ground

Water Yes Yes

3050

Coronado

Drive

No groundwater

extraction at any

depth without

approval from the

RWQCB and any

other agency with

jurisdiction.

12/30/1991

2.4. Operation and Maintenance (O&M)

The GWET was discontinued in 2001, ending active O&M. Honeywell continues to conduct semi-annual

groundwater monitoring and submits monitoring reports to the RWQCB and EPA.

3. Progress Since the Last Five-Year Review

3.1. Previous Five-Year Review Protectiveness Statement and Issues

The protectiveness statement from the 2012 Five-Year Review for the Site stated:

A protectiveness determination of the remedy at the Synertek Site cannot be made until after a

vapor intrusion assessment is completed in the former Synertek building. All other exposure

pathways that could result in unacceptable risks are being controlled, and institutional controls

are preventing exposure to, or the ingestion of, contaminated groundwater. The Five-Year

Review addendum, which will include the protectiveness determination, will be completed by

June 30, 2013.

The 2012 Five-Year Review included four issues and recommendations. Each recommendation and the

status is discussed below.


Table 4. Status of Recommendations from the 2012 Five-Year Review

Issue Recommendations Status Current Implementation Status

Description

Completion

Date (if

applicable)

The potential for indoor air

vapor intrusion in Building 1

should be evaluated.

Conduct indoor air and sub-slab

testing to determine if there is

current or potential future

exposure of building occupants to

Site contaminants through VI.

Completed VI testing has been completed, and the VI

pathway was found to be either

incomplete or insignificant.

11/30/2015

The Site clean-up

requirements and ROD specify

the final remedial action plan

for the Site to be a GWET

system, which has not

operated since 2001.

Testing of an alternative remedy,

Enhanced In-Situ Bioremediation

(EISB), is currently underway. A

Focused Feasibility Study is

needed to evaluate alternative

remedies to GWET and provided

the basis for amending the ROD.

Ongoing A Focused Feasibility Study has been

completed and is currently is under

review.

9/30/2013

The existing restrictive

covenant is not consistent with

current State law (California

Civil Code section 1471)

which establishes the

framework for environmental

covenants in California.

A restrictive covenant should be

recorded for the Site that is

consistent with current California

law.

Ongoing An updated restrictive covenant has been

drafted and reviewed by EPA and

RWQCB and sent to Synertek for

finalization.

N/A

There has been a slight

increase in 1,1-DCE in

monitoring well MW-29A.

The groundwater monitoring

program should be expanded to

determine the cause of this slight

increase.

Ongoing Monitoring wells MW-36A, MW-35A,

and PW-5 were reintroduced into the

monitoring program. Further discussion

of this issue continues in Data Review

section 4.2.1

N/A


3.2. Work Completed at the Site During this Five-Year Review Period

Work completed at the Site during this Five-Year Review period included groundwater monitoring, a

vapor intrusion investigation, and the submission of a Focused Feasibility Study (FFS). A VI

investigation was conducted from 2013 to 2014 for Building 1 and an off-site building. Section 4.2.2

summarizes the results of this investigation.

With discontinuation of the groundwater extraction and treatment system in 2001, the RWQCB

approved monitored natural attenuation (MNA) as the Site’s groundwater remedy. However,

biodegradation parameters such as dissolved oxygen, oxygen reduction potential, and pH, have

remained constant. From 2011 to 2013, Honeywell completed an Enhanced In-Situ Bioremediation

(EISB) pilot test. On September 30, 2013, CH2MHill submitted a FFS to the RWQCB including the

results of the EISB pilot test. The FFS is still under review by staff at the RWQCB and EPA.

New redevelopment continues near the Site, which has resulted in several off-property wells having to

be decommissioned or protected. Wells MW-28A and MW-34A were decommissioned without

replacements. Downgradient wells MW-29A and MW-33A, as well as upgradient well MW-1A, were

selected for special protection during the construction to ensure availability for future use.

A restrictive land use covenant is in place restricting well development on Site property. Honeywell’s

consultant, CH2MHill, has updated the deed restriction language to be consistent with California law.

The updated deed restriction is currently under review by staff at EPA and the RWQCB.

4. Five-Year Review Process

4.1. Community Notification and Site Interviews

A public notice was posted in the Santa Clara Weekly on June 14, 2017, stating that there was a five-

year review and inviting the public to submit any comments to the EPA. The results of the review and

the report will be made available at the Site information repository located at RWQCB, 1515 Clay St.,

Oakland, CA 94612.

During the Five-Year Review process, interviews were conducted to document remedy

implementation, as well as provide an opportunity for stakeholders to give feedback. The site team

conducted two interviews. The first interview was conducted during the Site inspection with the

Honeywell Site Project Manager, Cindy Schultz of CH2M Hill. Cindy stated that she was encouraged

by the results of the EISB pilot tests completed for the FFS. The only O&M issue identified was that

the construction activities in the area damaged some monitoring wells, thereby requiring well

reconstruction.

The second interview was conducted via email with George Cook, an Associate Engineering Geologist

with the Santa Clara Valley Water District. Mr. Cook stated that the remediation was going well, the


RWQCB staff was responsive, and the Santa Clara Valley Water District and RWQCB have an

effective working relationship.

4.2. Data Review

4.2.1. Ground Water

The Regional Water Quality Control Board (RWQCB) and Environmental Protection Agency (EPA)

reviewed groundwater data collected from 2012 to 2017 to evaluate the groundwater contaminant

plume and its behavior in the absence of active pumping since 2001. Trichloroethene (TCE)

concentrations in monitoring wells on the Synertek property and in the off-property area are declining

or remaining relatively stable, which demonstrates that the contaminant plumes in both aquifers are

stable.

Aquifer Zone A: TCE concentrations in most of Aquifer Zone A wells have generally remained

stable since the shutdown of the GWET system. The groundwater contamination in the Aquifer Zone

A extends approximately 600 feet to the east of the Site. TCE concentrations in the A-aquifer ranged

from non-detect (less than 0.1 µg/L) to 110 µg/L. The highest TCE concentration detected in the A-

aquifer was from well MW-12A (110 µg/L), which is located just downgradient of the source area.

Concentrations of TCE at MW-12A have remained stable since approximately 2003. The TCE

concentration in MW-07A, a monitoring well located on-property, decreased from as high as 99 µg/L

(in June 2008) to less than the clean-up standard after the 2011 pilot Enhanced In-situ Bioremediation

test, and sampling results from MW-07A were less than the TCE clean-up standard in 2015 and 2016.

The highest concentration of TCE detected in off-property samples was from monitoring well PW-4,

located southeast of the intersection of Montgomery Drive and Scott Blvd. In October 2016, TCE

levels in PW-4 were 44 μg/L, decreasing from a concentration of 54 μg/L in 2012. TCE has exhibited

a seasonal behavior at PW-4, with higher concentrations reported during the fall groundwater

monitoring event since approximately 2006. Monitoring wells MW-17A and MW-19A were sampled

in 2016 to supplement data from adjacent to the site. At these monitoring locations, TCE fluctuated

between 3.3 and 13 μg/L in 2016.

Degradation daughter products of TCE and 1,1,1-TCA (1,1-DCE, 1,1-DCA, cis-1,2-DCE and vinyl

chloride) have also been detected at concentrations above their respective clean-up levels within the

footprint of the TCE groundwater plume. Since the EISB injection event in the source area in 2011,

injection area monitoring wells (MW-07A, MW-37A, and MW-04B) have shown decreases in TCE

concentrations and temporary increases in vinyl chloride and ethene concentrations. In other locations

of the plume, the degradation daughter product concentrations have exhibited stable or decreasing

trends.

In April 2015, the groundwater contamination plume did not extend to the furthest downgradient

monitoring wells, MW-34A and MW-33A. However, since then, MW-34A had been decommissioned

and MW-33A has been temporarily inaccessible due to construction.


Figure 2. TCE Distribution in Aquifer Zone A


Aquifer Zone B: Aquifer Zone B contamination has not migrated down-gradient to the extent of

Aquifer Zone A contamination, and is currently limited to one well, MW-04B, located on the Synertek

property. The maximum TCE concentration within Aquifer Zone B in 2016 was 88 μg/L in

monitoring well MW-04B, but the levels have varied from 39 μg/L to 170 μg/L during the five-year

period. Concentrations of the degradation daughter products, 1,1-DCE and 1,1-DCA, have also been

detected in MW-04 for the past five years. Another degradation daughter product, vinyl chloride,

concentrations increased after the EISB activities were conducted in early 2011 from 0.2 μg/L in

December 2010, to 58 μg/L in October 2013, to 790 μg/L in October 2014 and subsequently decreased

to 140 μg/L in October 2016. Similarly, concentrations of vinyl chloride at PW-3, which had shown

non-detect concentrations since 2001, increased after the EISB activities were conducted in early 2011

from non-detect in June 2011 to 28 μg /L in May 2013, and subsequently decreased to 11 μg/L in

April 2015, followed by 6.5 μg/L in April 2016.


Figure 3. TCE Distribution in Aquifer Zone B


4.2.2. Vapor Intrusion

On May 31, 2013, Honeywell conducted a vapor intrusion pathway investigation at the Site. Vapor

intrusion is the phenomenon where VOCs in groundwater volatilize and can enter the air inside a

building, usually through openings in the foundation such as utility conduits entry points or cracks. This

pathway then can expose occupants to unsafe levels of air contamination. The vapor intrusion

investigation included indoor air and sub-slab soil vapor sampling in Building 1. Results from this testing

indicated that the VI pathway is either not complete or insignificant under current building use. The

RWQCB then requested additional indoor air and sub-slab soil vapor samples be collected when the

HVAC system for Building 1 was off-line. Results also indicated that VI pathway is either not complete

or insignificant with HVAC off. Honeywell also conducted a similar vapor intrusion investigation at an

off-site building located at 3111 Coronado Drive, also with the HVAC on and off. The analysis of the

results from this additional investigation indicated that the VI pathway is either not complete or

insignificant off-site.

4.3. Site Inspection

A site inspection was conducted on January 26, 2017. Melanie Morash (EPA), David Barr (California

RWQCB), Jacob Williams (USACE), and Cindy Schultz (CH2M Hill) were in attendance. The

inspectors confirmed that there were no active systems in operations and the Site was found to be in good

overall condition. The inspection team noted that some well vaults were not locked or secured properly,

which could pose a future risk, since the well vaults are in a business commercial area with many

businesses and employees.

5. Technical Assessment

5.1. Question A: Is the remedy functioning as intended by the decision

documents?

The remedy components currently in place, monitoring and an institutional control, are functioning as

intended. The restrictive covenant restricts groundwater extraction preventing exposure to on-site

contaminated groundwater. The remedy also requires the control of groundwater contamination

migration by a GWET system. While the GWET is no longer in operation, historical GWET operation

had successfully reduced chemicals of concern to much lower concentrations. By 2000, the GWET

system reduced the average TCE concentrations in Aquifer Zone A by 93 percent, and in Aquifer Zone B

by 99 percent, but eventually reached the point where operation of the GWET system was no longer

effective at reducing concentrations of the chemicals of concern.

Since shutdown, there have not been significant changes in the size of the plume, location, or

concentration of contaminants; however, ROD groundwater clean-up standards have not been met.


A Focused Feasibility Study was submitted to RWQCB and EPA in 2013, which evaluated alternative

treatment technologies to achieve the remedial action objectives in the 1991 ROD. It is anticipated that

EPA and RWQCB will select a new remedy by September 2020.

5.2. Question B: Are the exposure assumptions, toxicity data, clean-up

levels, and remedial action objectives (RAOs) used at the time of

remedy selection still valid?

The exposure assumptions, toxicity data, and remedial action objectives used at the time of remedy

selection are still valid. There were no changes to ARARs that affect protectiveness. There have been no

physical changes or changes in land use for the Site; consequently, exposure assumptions in the ROD

remain the same. The ROD did not consider vapor intrusion, which was evaluated in the last five years.

The vapor intrusion pathway was found to be incomplete, or insignificant, thus not a source of exposure

to Site contaminants (Section 4.2.3). There have been changes to the toxicity values for two of the

chemicals of concern: acetone and toluene. However, even with the change in toxicity values, the clean-

up levels remain below acceptable risk range and thereby are still considered protective (See Appendix

F).

Progress towards meeting the groundwater restoration RAO is underway with the development and

submittal of a groundwater Focused Feasibility Study (FFS). The FFS was submitted to EPA and

RWQCB on September 30, 2013. In 2020, EPA intends to issue a Proposed Plan, hold a public meeting

and ultimately issue a ROD Amendment to modify the remedy for groundwater.

5.3. Question C: Has any other information come to light that could call

into question the protectiveness of the remedy?

There is no other information that has come to light that changes the protectiveness of the remedy.

6. Issues/Recommendations

Table 5. Issues and Recommendations Identified in the Five-Year Review

OU(s): Issue Category: Remedy Performance

Issue: The selected remedy will not achieve remedial action objective of groundwater

restoration for future potential use as drinking water.

Recommendation: Select a new remedy by issuing a decision document.

Affect Current

Protectiveness

Affect Future

Protectiveness

Party Responsible Oversight Party Milestone Date

No Yes EPA/State

EPA/State 9/7/2020


7. Protectiveness Statement

Table 6. Protectiveness Statement

8 Protectiveness Statement

Protectiveness Determination:

Short-term Protective

Protectiveness Statement:

The remedy at Synertek, Inc. (Building 1) Superfund Site is currently protective of human health and

the environment because institutional controls are preventing exposure. However, for the remedy to be

protective in the long-term, a new remedy needs to be selected since the groundwater extraction and

treatment system is no longer operating.

8. Next Review

The next five-year review report for the Synertek, Inc. (Building 1) Superfund Site is required five years

from the completion date of this review.


Appendix A: Site Chronology

Site developed from agricultural land to a business park 1974

A 200-gallon solvent tank and three neutralization tanks are installed at Synertek 1974 - 1982

Synertek submits completed San Francisco Bay Regional Water Quality Control Board

(Regional Board) Facility Questionnaire

1982

Groundwater contamination discovered at the Synertek, Inc. (Building 1) Site 1982

The 200-gallon solvent tank and three neutralization tanks are determined to be a source of

contamination on the site and are removed

1985

Groundwater extraction and treatment begins from three on-site extraction wells. 1987

Regional Board adopts National Pollution Discharge Elimination System (NPDES) Permit

No. CA0029211 (Order No. 87-050) for the discharge of treated extracted groundwater at

the site

1987

Initial Site Clean-up Requirements adopted 1987

Synertek, Inc. (Building 1) Site is added to the National Priorities List (NPL) 1989

Two off-site groundwater extraction wells are added 1989

Revised Site Clean-up Requirements adopted 1989

Regional Board adopts Order No. 91-051, the final Site Clean-up Requirements specifying

the final Remedial Action Plan (RAP) for the site

1991

Record of Decision signed by the Environmental Protection Agency (EPA) 1991

Public Health Assessment completed by the Agency for Toxic Substances and Disease

Registry (ATSDR), and the California Department of Health Services (CDHS)

1992

Regional Board issues coverage under Order No. 94-087, General NPDES Permit No.

CAG912003, general permit for the discharge or reuse of extracted, treated groundwater

resulting from the cleanup of groundwater from volatile organic compounds

1994

First Five-Year Review completed 1996

Regional Board issues coverage under Order No. 99-051, General NPDES Permit No.

CAG912003, general permit for the discharge or reuse of extracted, treated groundwater

resulting from the cleanup of groundwater from volatile organic compounds (VOCs)

1999


Regional Board allows the groundwater extraction and treatment (GWET) system to be

shut down in response to a significant decline in contaminant removal rates and monitored

natural attenuation begins

2001

Second Five-Year Review completed 2002

Third Five-Year Review completed 2007

Enhanced in-situ bioremediation (EISB) Pilot Test begins to reduce the residual mass of

VOCs in the source area

2011

Fourth Five-Year Review completed 2012

To address Five-Year Review recommendation regarding Vapor Intrusion (VI), Agencies

request preparation of a VI Assessment Work Plan for the “on-property” building

2012

VI Assessment Work Plan for the “on-property” building submitted to the Agencies

(Heating, Ventilation and Air-Conditioning [HVAC]-on)

2012

Focused Feasibility Study (FFS) submitted to the Agencies 2013

Regional Board approves HVAC-on VI Assessment Work Plan for the “on-property”

building

2013

HVAC-on VI Assessment of “on-property” building completed 2013

EPA Region 9 provides supplemental guidelines to Regional Board on VI assessments at

State-lead South Bay Superfund sites

2013

Per EPA Region 9 guidelines, Regional Board requires the Responsible Party (RP) to

prepare and submit an additional Work Plan for HVAC-on/HVAC-off VI assessments at

both “on-property” and “off-property” buildings

2013

HVAC-off VI Assessment Work Plan for the “on-property” and “off-property” buildings

submitted to the Agencies

2014

Regional Board approves HVAC-off VI Assessment Work Plan 2014

HVAC-off VI Assessment completed 2014

Regional Board approves findings of VI Assessment for the “on-property” building 2015

Regional Board approves findings of VI Assessment for the “off-property” building 2015


Appendix B: List of Documents Reviewed

California Regional Water Quality Control Board, San Francisco Bay Region (RWQCB). 1991. Order

No. 91-051, Site Cleanup Requirements for Honeywell Inc. and The RREEF Funds, Former Synertek #1

Facility, 3050 Coronado Drive, Santa Clara, Santa Clara County.

CH2M Hill Engineers, Inc. (CH2M). 2012a. Vapor Intrusion Investigation Work Plan, Former Synertek

Building No.1 Facility, Santa Clara, California. June 29.

_____. 2012b. Revised Vapor Intrusion Investigation Work Plan, Former Synertek Building No. 1

Facility, Santa Clara, California. October 2.

_____. 2013a. Focused Feasibility Study, Former Synertek Building No. 1 Facility, Santa Clara,

California. September 30.

_____. 2013b. Vapor Intrusion Evaluation Report, March/April 2013, Former Synertek Building No. 1,

3050 Coronado Drive, Santa Clara, California, Water Board Final Site Cleanup Requirements Order No.

91-051. May 31.

_____. 2014a. Additional Vapor Intrusion Evaluation Work Plan, Former Synertek Building No.1

Facility, Santa Clara, California. June 25.

_____. 2014b. Additional Vapor Intrusion Evaluation Report, June/July 2014, Former Synertek Building

No. 1, 3050 Coronado Drive, Santa Clara, California, Final Site Cleanup Requirements Order No. 91-

051. October 31.

_____. 2015. Addendum to the Additional Vapor Intrusion Investigation Report, Former Synertek

Building No. 1, 3050 Coronado Drive, Santa Clara, California. November 30.

_____. 2017. 2016 Groundwater Monitoring and Sampling Summary Report, Former Synertek Building

No. 1, 3050 Coronado Drive, Santa Clara, California. January 26.

U.S. Environmental Protection Agency (EPA). 1991. Superfund Record of Decision: Synertek (Building

#1), CA. June.

_____. 2012. Fourth Five-Year Review Report for Synertek, Inc. (Building 1) Superfund Site, 3050

Coronado Drive, Santa Clara, California. September.


Appendix C: Supplemental Data Information

Groundwater Extraction and Treatment System Operation

By the late 1990s, the amount of VOC mass being removed by the GWET system had declined

considerably, and VOC concentrations in groundwater seemed to be stabilizing. This phenomenon of an

initial significant reduction in VOC concentrations, followed by a leveling off in the reduction in VOC

concentrations, has been found to occur at many other sites in the area and around the country. In 2001,

the RWQCB approved a request by the Potentially Responsible Party to leave the GWET system shut

down to see whether the contaminant plume would remain stable, and if monitored natural attenuation

(MNA) could be an effective method of remediation. The GWET system has remained shut down since

then, and the Site has been monitored to ensure the plume is contained and to determine the effectiveness

of MNA. Groundwater monitoring since GWET shutdown has shown MNA will likely be unable to

restore the groundwater to its beneficial use as a potential drinking water source. The feasibility of

alternative remedies or improvements to the former system needs to be evaluated to ensure that the long-

term remedial objectives are achieved.

Monitored Natural Attenuation

The RWQCB has been assessing the effectiveness of MNA at Synertek, Inc. (Building 1) Site since the

GWET was discontinued in 2001. First, it has been observed that the daughter products of the primary

pollutants present in groundwater at the Site are present. TCE, 1,1,1-trichloroethane (1,1,1-TCA), and

Freon 113 are considered parent compounds released at the Site. Cis-1,2-dichloroethene (cis-1,2-DCE)

and vinyl chloride are sequential breakdown products of TCE. 1,1-DCE and 1,1-dichloroethane (1,1-

DCA) are breakdown products of 1,1,1-TCA. Vinyl chloride is a breakdown product of the DCE isomers.

The presence of breakdown products indicates that some biodegradation of the VOCs is occurring under

natural conditions in the plume. It was expected that the plume concentrations would slowly decrease

through the processes of natural attenuation. This has proven to be a slow process, and VOC

concentrations in most of the wells sampled have been generally stable.

Biodegradation parameters, such as dissolved oxygen, oxygen reduction potential, and pH, have been

monitored at the Site since the GWET system was shut down in 2001. The biodegradation parameters did

not significantly increase or decrease during this time. Based on the results of the monitoring program, the

primary natural attenuation processes are believed to be adsorption, dilution, and dispersion, with

conditions conducive to intrinsic biodegradation of VOCs present in some areas of the Site. Conditions

have not changed during the last five-year period.

Vapor Intrusion

A Vapor Intrusion Evaluation Report was submitted to the Water Board on May 31, 2013 evaluating

indoor air and sub-slab soil vapor samples for Building 1 at the Site (CH2M, 2013b). The vapor intrusion

study included the collection of eleven indoor air samples collected in the spring of 2013 under normal


building operations, which included operation of the HVAC system. All results were largely non-detect

or below residential screening levels except for one sample located in a clean room that had containers of

TCE. Sub-slab samples were collected after each indoor sampling event, and although TCE was detected,

the concentrations detected were well below TCE sub-slab screening levels. The report concluded that the

vapor intrusion pathway is not complete or significant under current building use, and that no further

action should be required.

The RWQCB issued a letter to the Honeywell, Inc. on December 16, 2013 requesting an additional VI

investigation work plan to address EPA guidance from December 3, 2013, and EPA Region VI guidance

for the South Bay National Priorities List sites. Based on the EPA guidance, RWQCB indicated that VI

sampling should additionally be performed with the building in a heating, ventilation, and air

conditioning (HVAC)-off condition and that the VI study areas should include buildings within the TCE

shallow-aquifer groundwater contour of 5 μg/L. This includes Building 1 on-site and one off-site

building, at 3111 Coronado Drive. Twenty-two indoor air samples were collected after the HVAC in the

on-site building had been off for 36 hours. All results were below the commercial/industrial screening

levels, except for the sample located in the clean room which slightly exceeded the screening level for

TCE of 2.4 µg/m3. Sub-slab samples were collected after each indoor sampling event, and although TCE

was detected, the concentrations detected were well below TCE sub-slab screening levels. The results of

the additional VI study concluded that the VI pathway is neither complete nor significant under current

building use, and that no further action should be required (CH2M, 2014b). At the time of the

investigation, access had not been granted at the off-site building north of the Site, 3111 Coronado Drive,

and the report did not include the off-site building.

The Additional Vapor Intrusion Evaluation Report was approved by the RWQCB on March 5, 2015, with

the condition that the planned VI evaluation at the off-site building would be conducted once access to the

building was granted. Access was granted in July 2015, and the off-site VI investigation was conducted.

Twelve indoor air samples were collected in August 2015 in two rounds. The first round was under

normal operating conditions and the second round was with the HVAC off for 36 hours prior to sampling.

All results were non-detect for TCE under normal operating conditions. TCE was either non-detect or

below the residential ESL with the HVAC off. Subsequent sub-slab soil gas samples were collected.

Although TCE was detected, the concentrations detected were well below TCE sub-slab screening levels.

The addendum that documents the investigation performed at the off-site building was submitted to the

RWQCB on November 30, 2015, as 2015 Addendum to the Additional Vapor Intrusion Investigation

Report (CH2M, 2015). The addendum concluded that the VI pathway is neither complete nor significant

under current building use and that no further action should be required. Figure B-1 and Tables B-1 and

B-2 give further information and data on the VI effort at both Building 1 on-site and the off-site building.


Figure B-1. Indoor/Outdoor Air and Sub-Slab Sampling Locations from Vapor Intrusion Work Plan, On-site Building 1


Note: See next table for notes, abbreviations, and further explanation of table.

Table B-1. Summary of Sub-Slab Soil Gas Volatile Organic Compound Results, Off-site Building


Table B-2. Summary of Indoor and Outdoor Air Volatile Organic Compound Results, Off-site Building


Appendix D: ARAR Assessment

Section 121(d)(1)(A) of CERCLA requires that remedial actions at CERCLA sites attain (or justify the

waiver of) any federal or state environmental standards, requirements, criteria, or limitations that are

determined to be legally applicable or relevant and appropriate requirements (ARARs). Federal ARARs

may include requirements promulgated under any federal environmental laws. State ARARs may only

include promulgated, enforceable environmental or facility-siting laws of general application that are

more stringent or broader in scope than Federal requirements and that are identified by the State in a

timely manner. ARARs are identified on a site-specific basis from information about the chemicals at the

site, the RAs contemplated, the physical characteristics of the site, and other appropriate factors. ARARs

include only substantive, not administrative, requirements and pertain only to on-site activities. There are

three general categories of ARARs: chemical-specific, location-specific, and action-specific.

Chemical-specific ARARs identified in the selected remedy within the Record of Decision (ROD) for the

groundwater at this Site are shown in Table C-1. Only ethylbenzene has a clean-up level (680 μg/L) that

is above its current State MCL of 300 μg/L, which was adopted in 2003. Ethylbenzene was detected in

the early years of the monitoring program, but has been non-detect with a detection limit of 0.5µg/L over

the past five years.


Table C-1. Summary of Groundwater ARAR Changes

Contaminants of Concern

1991 ROD

Groundwater

Clean-up

Level (μg/L)

Federal

MCL

(μg/L)

State

MCL

(μg/L)

Is the clean-

up level

above the

current

MCL?

acetone 350 NA* NA No

benzene 1 5 1 No

Bis(2-ethylexyl)phthalate

[Di(2-ethylhexyl)phthalate]

4 6 4 No

1,1-Dichloroethane (1,1-DCA) 5 NA 5 No

1,1-Dichloroethene (1,1-DCE) 6 7 6 No

Cis-1,2-Dichloroethene (cis-1,2-DCE) 6 70 6 No

ethylbenzene 680 700 300 Yes

Freon 113 1200 NA 1,200 No

styrene 5 100 100 No

toluene 100 1,000 150 No

1,1,1-Trichloroethane (1,1,1-TCA) 200 200 200 No

Trichloroethene (TCE) 5 5 5 No

vinyl chloride 0.5 2 0.5 No

xylenes 175 10,000 1,750 No

*NA- No level promulgated

Federal and State laws and regulations other than the chemical-specific ARARs that have been

promulgated or changed over the past 5 years are described in Table C-2. There have been no revisions to

laws or regulations that affect the protectiveness of the remedy.

The following ARARs have not changed since the last Five Year Review:

• Porter-Cologne Water Quality Control Act California Water Code Division 7, Chapter 4, Article

4 §13263

• Federal Clean Water Act (CWA) 33 USC 1251 et seq. Section 402 NPDES and California Water

Code Division 7, Chapter 3 Article 4, §13160

• Resource Conservation and Recovery Act 42 USC §6901 and California Hazardous Waste

Control Health and Safety Code Division 20, Chapter 6.5, Articles 4, 4.5, 5, 6.5, and 7.7

• Safe Drinking Water Act 40CFR 144.13(4)(C)


Table C-2. Applicable or Relevant and Appropriate Requirements Evaluation

Original ARAR

Docu

men

t

Original ARAR Requirement

Rev

ised

Req

uir

emen

t

Revision Date

(between 9/27/2012-

present)

Effect on Protectiveness

Solid Waste Hazardous Waste

Control as amended by Resource

Conservation and Recovery Act

42 USC §6901 and California

Hazardous Waste Control Health

and Safety Code Division 20,

Chapter 6.5, Articles 2, 4, 4.5, 5,

6, 6.5, and 7.7

1991

ROD Remedial activities involving on-site

management of hazardous wastes

from spent carbon disposal, storage,

and handling.

No

ne

The following applicable

amendments have been

made to CCR Division 20

Chapter 6.5.

• Article 2 §25123.3

• Article 6 §25160

• Article 6 §25162

None. The changes made to

California Hazardous Waste Control

Health and Safety Code Division 20

Chapters do not effect protectiveness

and concern the control of waste

disposal, manifest, and temporary

storage. Because the GWET system is

not operable there is no waste

generated.


Appendix E: Contaminants of Concern The Record of Decision (ROD) outlines 33 chemicals to be identified as contaminants of concern and of

the 33, fourteen were identified clean-up standards. Table E-1 identifies all chemicals of concern as listed

in the ROD and whether a clean-up standard was selected for that chemical.

Table E-1. Complete List of Contaminants of Concern from Record of Decision

Chemical

Was clean-up

standard selected

in ROD? Chemical

Was clean-up

standard

selected in

ROD?

Acetone Y Oxiranemethanol

Benzene Y 4-0H-2-Methyl Pentanone

Bis(2-ethylhexyl)phthalate Y 4-0H-4-Methyl-2-Pentanone

1-Butanol Phenol

3-Buten-2-one 2-Propanol

Butylbenzyl phthalate 1-Propylamine

Carbon disulfide Styrene Y

1,1-Dichloroethane (1,1-

DCA) Y Toluene Y

1,1-Dichloroethene (1,1-DCE) Y 1,2,4-Trichlorobenzene

cis-1,2-Dichloroethene (cis-

1,2-DCE) Y 1,1,1-Trichloroethane (1,1,1-

TCA) Y

Di-n-butyl phthalate Trichloroethene (TCE) Y

Ethanol 1,1,2-Trichloro-1,2,2-

trifluoroethane Y

Ethylbenzene Y 1,1,2-Trifluoro-1,2-

dichloroethane

2-Methyl-2-Hexanol 2,2,4-Trimethylpentane

Hexanoic Acid Vinyl Chloride Y

Methyl ethyl ketone (MEK) Xylenes Y

Methyl pentenone


Appendix F: Toxicity Analysis

MEMORANDUM January, 2017

Subject: Synertek, Inc. (Building 1) Superfund Site: Five Year Review Protectiveness

With the Respect to Changes in Toxicity Values.

From: Gerald F.S. Hiatt, Ph.D.

Senior Regional Toxicologist

To: File: Five Year Review, Synertek, Inc. (Building 1) Superfund Site

Revisions to toxicity assessments for site-related contaminants may call into question the

protectiveness of clean-up levels established in the Record of Decision (ROD) for a Superfund site.

Thus, it may be appropriate during a site's Five Year Review (FYR) to re-evaluate protectiveness for

contaminants where risk-based clean-up levels were chosen in the ROD.

Clean-up levels at Superfund sites are typically set to either Applicable or Relevant and

Appropriate Requirements (ARARs), such as drinking water Maximum Contaminant Goals

(MCLs). When an ARAR is not available for a particular contaminant, the National

Contingency Plan (NCP) directs EPA to set a clean-up level that is "protective of human

health and the environment", usually based on the risk assessment for the site.

While ARARs are "frozen" at the time of the ROD and therefore typically do not require reassessment

during a FYR, risk-based clean-up levels should be re-evaluated in light of any revisions to underlying

toxicity assessments, in order to ensure continued protectiveness. If a Superfund site remedy is

intended to meet a site-specific, risk-based clean-up level, the FYR guidance requires EPA to assess

whether toxicity or other contaminant characteristics used to determine the original clean-up level

have changed and whether it remains protective in light of the change(s).

At the Synertek, Inc. (Building 1) Superfund Site, the following chemicals of concern and their clean-

up levels are identified in the following table:


Table F-1: Clean-up Standard from 1991 ROD

Chemical 1991 Clean-up

Standards

(µg/L)

1991 Basis for Standard

Acetone 350 Hazard Index1

Benzene 1 CA MCL2

bis(2-ethylhexyl)

phthalate 4 CA MCL

1,1-dichloroethane 5 CA MCL

1,1-dichloroethene 6 CA MCL

cis-1,2-dichloroethene 6 CA MCL

Ethylbenzene 680 CA MCL

Freon-113 1200 CA MCL

Styrene 5 Proposed EPA MCL

Toluene 100 CA DHS Action Level

1,1,1-trichloroethane 200 CA MCL

Trichloroethene 5 CA MCL

Vinyl chloride 0.5 CA MCL

Xylenes 175 1/10th of the CA MCL

Of the 14 chemicals of concern, two relied on risk based numbers to selected a clean-up level: acetone

and toluene.

In the 1991 Synertek ROD, EPA selected the California state "Action Level" as the clean-up level for

toluene. The treatment standard chosen for toluene was the Action Level of 100 µg/L.

Action Levels for groundwater contaminants were developed by the California Department of

Health Services (CDHS; now Department of Public Health [CDPH]) in the 1980s and 1990s;

these action levels were meant to provide information on health protective concentrations for

contaminants lacking a drinking water standard (MCL).


The clean-up standard chosen for acetone was a risk-based concentration equivalent to a Hazard

Quotient of 0.1 (HQ=0.1), thus the acetone clean-up level was set at 350 µg/L.

Protectiveness Determination: For these 2 contaminants, a protectiveness determination using current

toxicological and risk assessment information was made by comparing the 1991 ROD clean-up

standards to current risk based screening levels, the Superfund RSLs (Regional Screening Levels).

RSLs incorporate current contaminant toxicity values into risk assessment scenarios to generate

contaminant concentrations in impacted media that are protective of human health as defined in the

NCP. RSLs are not de facto clean-up levels for a Superfund site; rather as risk-based screening levels

they provide a reliable indication of whether additional actions may be needed to address potential

human health exposures.

The RSLs for carcinogens are chemical-specific concentrations that correspond to an excess

lifetime cancer risk (ELCR) of 1x10-6, which is the lower boundary of the Superfund

protective range for cancer risks (ELCR = 10-6 to 10-4) as defined in the NCP. RSLs for

contaminants posing non-cancer health hazards are concentrations corresponding to a Hazard

Quotient = 1.0 (HQ=1). HQ=1 RSLs represent "concentration levels to which the human

population, including sensitive subgroups, may be exposed without adverse effect during a

lifetime or part of a lifetime, incorporating an adequate margin of safety", as specified in the

NCP.

To evaluate the protectiveness of the clean-up levels for 1,1-DCA and nickel in this FYR, their clean-

up levels were compared to EPA’s current tapwater RSLs.

Acetone: Regarding acetone, the current (May 2016) non-cancer RSL for acetone in tapwater is

14,000 µg/L. By comparison to the tapwater RSL, the treatment standard chosen for acetone in the

1991 ROD corresponds to a Hazard Quotient of 0.025; this calculated Hazard Quotient is well below

the Hazard Quotient of 1.0 which is the protectiveness goal for non-cancer hazards established in the

NCP and an exposure concentration below which no adverse effects would be expected. This

calculated Hazard Quotient is also below the 0.1 Hazard Index reference for which the clean-up

standard was based and is thus still considered protective.

Toluene: Regarding toluene, there is both a drinking water MCL (1,00 µg/L) and a non-cancer RSL

(1,100 µg/L; May 2016 RSL table). The 1991 ROD clean-up standard is below (more protective) than

both. By comparison to the tapwater RSL, the treatment standard chosen for toluene in the 1991 ROD

corresponds to a Hazard Quotient of 0.09; this calculated Hazard Quotient is well below the Hazard

Quotient of 1.0 which is the protectiveness goal for non-cancer hazards established in the NCP and an

exposure concentration below which no adverse effects would be expected and is thus still considered

protective.

Conclusion: Viewed in the context of current toxicity information and risk assessment standards and

practices, the treatment standards for acetone and toluene chosen in the 1991 ROD remain protective

for use of groundwater at the Synertek site.


Appendix G: Interview Forms


Five-Year Review Interview Record

Site: Synertek

EPA ID No:

CAD0990832735

Interview Type: Email

Location of Visit:

Date: 3/28/2017

Time: 0900

Interviewers

Name Title Organization

Peter Gibson Remediation Biologist USACE

Interviewees

Name Organization Title Telephone Email

George Cook

Santa Clara Valley Water District

Associate Engineering Geologist 4086302964

[email protected]

Summary of Conversation

1) What is your overall impression of the project? Due to resources and other priorities the District currently only provides more detailed review of about 12 other sites that are considered higher priority. The District prioritized the sites within the Santa Clara and Llagas Subbasins in 2009. This prioritization was based on current concentrations, plume length, proximity to nearest receptor, groundwater vulnerability rank, and remedial progress. The Synertek site was not included as a priority site for our review. The District's impression of the site follows: a. The remaining contaminants are at relatively low concentrations and the plume is stable or shrinking b. The contaminants are in the shallow aquifer, which is separated from the principal aquifer by a thick clay layer aquitard. Although the District considers all groundwater a potential source of drinking water, the principal aquifer below the regional aquitard is the primary concern as it is where most groundwater is extracted. c. The responsible parties have been responsive and are making good progress in addressing the site. 2) What is your organization's involvement with the site and how often do you do work with the site? The District has not provided a regular review of site activities since about 2006. The District does provide permitting for well construction and destruction at the site. 3) Have there been routine communications or activities conducted by your office regarding the site? No 4) Have there been any complaints, violations, or other incidents related to the site requiring a response by your office? If so, please give details of the events and results of the responses. We are not aware of any complaints, violations, or other incidents related to the site. 5) Do you feel well informed about the sites activities and progress? As the District, does not closely review this case we are not well informed, but the information is readily available to us if necessary. The District has a good working relationship with the San Francisco Bay Regional Water Quality Control Board (Water Board). The Water Board staff has done a good job and alerts the District if any issues arise. 6) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the remedy? No 7) Do you have any comments, suggestions, or recommendations regarding the project? The site has undergone significant remedial effort, including removal of more than 90% of VOCs by groundwater extraction and treatment, confirmation of natural attenuation through effective monitoring, extensive investigation of the VI pathway and confirmation that no risk is present, focused investigation and implementation of enhanced bioremediation, and comprehensive analysis of accumulated data. The District feels that the work conducted at this site by different consultants has been of generally good technical quality, reflecting effective management of remedial efforts by the RP, and effective oversight by the RWQCB.

Additional Site-Specific Questions

[If needed]


Appendix H: Site Inspection Checklist Photographs from Site Inspection Visit


Note “Other” box is checked and enhanced in-situ bioremediation is written in as an element of

the remedy. While enhanced in-situ bioremediation is occurring on the site as part of a focused

feasibility study it is not part of the Record of Decision or and therefore not part of the remedy.


Photo 1: North of site


Photo 2: On-site monitoring well


Photo 3: Synertek Site building back side


Photo 4: Synertek building front of building


Photo 5: GWET system


Photo 6: PW:4


Photo 7: EW vault


Photo 8: MW-12B


Photo 9: MW 3-B


Photo 10: NW corner of the site with monitoring wells


Photo 11: Side of Site building.


Photo 12: Site building with locations for other businesses.


Appendix J: Public Notice

Fifth Five Year Review Report - Records Collections

Documents

Transcript of Fifth Five Year Review Report - Records Collections