Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Advanced Micro Devices, Inc.
EPA #: CAD048634059
County: Santa Clara
Congressional District: 14
Other Names: AMD 901 / 902 AMD - Thompson Place
EPA is currently evaluating the potential for vapor intrusion in buildings overlying the shallow groundwater contamination area. On December 3, 2013, EPA sent a letter to the State of California's Regional Water Quality Control Board providing guidelines for vapor intrusion sampling and evaluation at this and 10 other South Bay State-lead sites.
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 10/15/84
Final Date: 06/10/86
The former Advanced Micro Devices, Inc. 901/902 Thompson Place Superfund Site (Site) covers 6 acres in Sunnyvale, California. AMD designed and fabricated semiconductor devices at two adjoined low-rise buildings at the Site between 1969 and 1992. Groundwater beneath the site is contaminated by volatile organic compounds (VOCs), including trichloroethene (TCE). Two below-ground acid neutralization system (ANS) tank vaults were located at the northern and southern ends of the 901 and 902 Thompson Place buildings, respectively. Leaks from these ANS tanks appears to be the primary on-site source of VOCs to groundwater in this area. The two tanks were removed in 1983 and 1984 and the impacted soil was excavated and transported to a disposal facility. The property was sold and redeveloped in 2007 as a self-storage facility.
The Site neighbors multiple other sites, including: the TRW Microwave Superfund Site (TRW Site); the AMD 915 DeGuigne Drive Superfund Site (AMD 915 Site); and the Philips Semiconductor Site (Philips Site; formerly Signetics Inc.), which includes the properties at 811 Arques Avenue, 440 North Wolfe Road, and facilities along Stewart Drive. The Mohawk Laboratories Site is located to the south of the Site.
The Site is part of the “Triple Site,” which also includes the TRW Site, the Philips Site, and an “Off-site Operable Unit” (OOU), where a commingled plume of contaminants from the other three sites is located. This plume consists of VOCs, including TCE, and extends from these sites more than a mile north in Sunnyvale to past Highway 101.
The Site is listed on the National Priorities List (NPL) and covered by a 1991 Record of Decision (ROD) for the Triple Site. The four OUs for the Triple Site are as follows:
(1) The AMD 901/902 Site OU;
(2) The Philips Site OU;
(3) The TRW Microwave Site OU; and
(4) The Companies Offsite Operable Unit (OOU), a commingled plume of contaminants which originated from the other three operable units (and has contributions from other sites in the area).
At the time of adoption of the 1991 ROD, the OOU was defined as a 100-acre area, downgradient and north of the Triple Site in an area bounded by the Sunnyvale East Drainage Channel on the west and Santa Paula Avenue on the east, and as the area inside a 5 micrograms per liter (µg/L) isopleth for trichloroethene (TCE) in groundwater. Over 1,200 residences and 4 schools are present within the OOU. The closest residence is approximately 2,000 feet north of the Site.
Drinking water in this area is not affected by the groundwater contamination. In this part of Sunnyvale, drinking water comes from the Hetch Hetchy Reservoir in the Sierra Nevada Mountains, and is tested regularly to ensure that it meets all applicable state and federal drinking water standards.
Contaminants and Risks
- Soil and Sludges
Groundwater beneath the Site is contaminated with volatile organic compounds (VOCs), including trichloroethene (TCE), from leaking underground storage tanks and piping. VOC contamination was historically present in soil but has been remediated to below regulatory criteria. Institutional controls are in place to ensure that no one can ingest or come in direct contact with contaminated groundwater.
A vapor intrusion investigation conducted at the on-Site building concluded that VOCs in groundwater are not impacting indoor air quality through vapor intrusion (a process whereby vapors from contaminated groundwater move upwards through the soil and enter the indoor air of nearby buildings). EPA is in the process of evaluating the results of the vapor intrusion investigation and determining the need for any additional action.
The Site contamination is not impacting municipal drinking water supplies.
Who is Involved
This site is being addressed through Federal and potentially responsible parties' actions.
Immediate Actions: After the two acid neutralization tanks were removed, AMD excavated and disposed of soil impacted with VOCs, and installed a groundwater extraction and treatment system. Extracted groundwater was treated with air stripping technology followed by carbon adsorption.
Under State supervision, AMD completed an investigation determining the nature and extent of contamination at the Site. EPA selected a cleanup remedy in late 1991, which called for excavating contaminated soil, continuing the operation of the existing groundwater extraction and treatment system, and installing new wells at the leading edge of the off-Site commingled plume. Excavation of the soil and well installation were completed in late 1992.
The groundwater extraction and treatment system began operating in 1983 and continued through 2002, when it was discontinued with State approval to allow for an in-situ bioremediation (ISB) pilot test. The full-scale ISB system, which was initially pilot-tested from 2002 through 2004, and then expanded in 2005, includes groundwater treatment by carbon filtration and injection of an organic carbon source to stimulate the growth of naturally-occurring microbes that break down target VOCs into environmentally-benign end products.
Cleanup Results to Date
Construction of all cleanup remedies is complete at the Site. The removal of underground tanks and contaminated soil, the previous operation of the groundwater treatment system, and the ongoing operation of the in-situ bioremediation (ISB) system are helping to keep contaminant levels within acceptable limits and preventing the spread of contaminants.
The most recent Five-Year Review was completed in September 2014 and concluded that the remedy at the Site is currently protective of human health and the environment. Although the groundwater extraction system has been turned off, the in-situ bioremediation groundwater program is continuing to make progress towards groundwater restoration and institutional controls are in place to prevent exposure to contaminated groundwater.
However, to be protective in the long-term, the Record of Decision (ROD) for the Site should be amended to reflect a revised, final groundwater remedy for the Site since the groundwater treatment remedy selected in the ROD is no longer operation.
Additionally, the 2014 vapor intrusion evaluation at the on-site building indicated that potential indoor air exposures due to Site groundwater contamination are not a concern. However, the need for vapor intrusion evaluations was not assessed for the remaining seven buildings currently occupying the Site, but located upgradient of the former source area. The Five-Year Review also recommended completing vapor intrusion assessments in the residential/school area adjacent to the Site (within the Offsite Operable Unit or OOU.
EPA has been conducting indoor air evaluations in the OOU throughout 2015, and will evaluate the need for conducting additional indoor air assessments at the seven other commercial buildings on-site in 2016. More information about the OOU indoor air sampling (Duane/San Miguel Avenue neighborhood) may be found at the following website: www.epa.gov/region9/triplesite
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
The PRP for the Site is Advanced Micro Devices, Inc.
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
Regional Water Quality Board
San Francisco Bay Region
2101 Webster Street, Suite 500
Oakland, CA 94612
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
After Hours (Emergency Response)