intersil inc./siemens components

10900 N TANTAU AVE/19000 HOMESTEAD RD

The Intersil/Siemens Superfund Site includes the following three areas: 1) the former Intersil facility, located at 10900 North Tantau Avenue, Cupertino; 2) the former Siemens facility, located at 10950 North Tantau Avenue, Cupertino; and 3) the Off-Site Study Area, located north of and hydraulically downgradient from the two former facilities in Sunnyvale. Investigations conducted in the 1980s as part of the California Regional Water Quality Control Board's (Regional Board’s) underground storage tank (UST) leak detection program found volatile organic compounds (VOCs) in soil on- and off-site. The primary VOC at the site is trichloroethene (TCE). • Former Intersil Facility - Intersil, Inc. operated at the property from 1968 to 1988 and initiated investigations in 1983. The potential sources of contamination were removed between 1986 and1988, including waste neutralization systems, a waste solvent tank, and an above-ground chemical and hazardous waste storage area. • Former Siemens Facility - Litronix and its successor, Siemens Microelectronics, Inc., operated at the property from 1970 to the mid-1990s. Until 1982, liquid wastes were stored in five USTs that were removed in 1982. From 1982 until cessation of operations, liquid wastes previously stored in USTs were temporarily placed in the hazardous materials storage area for off-site disposal or recycling. Investigations began in 1982 after the discovery of contaminants during the removal of the USTs. Drinking water for Sunnyvale and Cupertino is not affected by this contamination. Calabazas Creek, an intermittent stream, is located approximately 1,500 feet east of the site. Historically, the shallow saturated sediments at the site were divided into three water-yielding zones: the A zone, B zone, and C zone. Regional groundwater elevations rose approximately 50 to 55 feet between 1993 and 1998 from a historic depth of approximately 100 feet below ground surface (bgs). Based on 2013 water level measurements, groundwater is first encountered beneath the site at depths ranging from approximately 35 to 50 feet bgs. Due to the water level rise, the A zone has been further subdivided into A1, A2, A3, and A4 depth intervals.

• Fresno Municipal Sanitary Landfill (Fresno, CA)
• Oeser Co. (Bellingham, WA)
• Intel Corp. (mountain View Plant) (Mountain View, CA)
• Hanford 300-area (usdoe) (Benton County, WA)
• Iron King Mine - Humboldt Smelter (Dewey-humboldt, AZ)

• Fairchild Semiconductor Corp. (mountain View Plant) (Mountain View, CA)
• Hassayampa Landfill (Hassayampa, AZ)
• Mccoll (Fullerton, CA)
• Hanford 200-area (usdoe) (Benton County, WA)