The Advanced Micro Devices site covers six acres at 901/902 Thompson Place in Sunnyvale, California. Semiconductor devices were made there from 1969 to 1992. Leaks from two underground acid neutralization tanks released trichloroethene (TCE) and other volatile organic compounds (VOCs) into the soil and groundwater. EPA added the site to the National Priorities List in 1986, and the final cleanup plan was selected in September 1991.
EPA has identified 19 contaminants at the site, found in both groundwater and soil. They include TCE, tetrachloroethene, vinyl chloride, 1,1,1-trichloroethane, and several other chlorinated solvents and related compounds. Contaminated soil has been cleaned up to below regulatory standards. Groundwater contamination remains and is part of a larger commingled plume, called the Triple Site, that stretches more than a mile north across Sunnyvale and sits beneath more than 1,000 homes and 4 schools. Municipal drinking water comes from the Hetch Hetchy Reservoir and meets all applicable standards.
Cleanup has included removing the tanks in 1983 and 1984, excavating contaminated soil, and running a groundwater extraction and treatment system from 1983 to 2002. Since 2002, an in-situ bioremediation system has used naturally occurring microbes to break down VOCs in place. The property was redeveloped in 2007 as a self-storage facility and now hosts 18 businesses employing 216 people. In October 2019, EPA reached settlements with Philips Semiconductors Inc., Advanced Micro Devices, and Northrop Grumman Systems Corporation to address vapor intrusion and groundwater cleanup at the Triple Site.
The Sixth Five-Year Review, completed in September 2024, found that current cleanup protects human health and the environment for existing commercial land use. However, soil gas and sewer gas investigations are still needed, and EPA needs to select a revised groundwater remedy because the extraction system is no longer operating. EPA has determined that human exposure is under control at the on-site building, but vapor intrusion into nearby homes and school buildings is still being addressed. More than 20 mitigation systems have been installed or are being installed in affected residences and classrooms.
Community members with questions can contact EPA's Community Involvement Coordinator or the Remedial Project Manager.
