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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

Intersil, Inc.-Siemens Components

EPA #: CAD041472341

State: California(CA)

County: Santa Clara

City: Cupertino

Congressional District: 14

Other Names:

Bulletin Board

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.


For more information, click any of the following to access the California State Water Resources Control Board GeoTracker web sites:

Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 06/24/88

Final Date: 08/30/90

Deleted Date:

Intersil, Inc. and Siemens Components have manufactured semiconductors for several years on two locations covering 15 acres. Siemens currently is an operating facility, while Intersil is now inactive. Investigations conducted in 1982 as part of the California Regional Water Quality Control Board's (CRWQCB) underground storage tank leak detection program found volatile organic compound (VOC) contaminated soils on- and off-site. This contamination is believed to have resulted from localized spills and from leaking underground storage tanks and piping from the two companies. At the Siemens facility, four underground tanks were used to store waste solvents. At the Intersil facility, possible sources of contamination include the waste neutralization systems and the concrete scrubber pit sumps. More than 300,000 people obtain drinking water from public wells located within 3 miles of the site. The groundwater is used for the municipal water supplies of the cities of Cupertino, Santa Clara, and Sunnyvale. Five municipal water supply wells are located within 1 mile of the site. Three of these wells, operated by the City of Santa Clara, are located hydraulically downgradient from the site. The distance from the site to the City of Santa Clara Well #15, the closest municipal well, is 1,300 feet. Calabazas Creek, an intermittent stream, is located approximately 1,500 feet east of the site.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • Air
  • Soil and Sludges

Groundwater, soil, and air have been contaminated with VOCs. Ongoing cleanup activities continue to reduce the potential health threats from direct contact with contaminated soils, ingestion of contaminated groundwater, inhalation of VOCs from the use of groundwater, and inhalation of chemicals released from the soils.

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Who is Involved

This site is being addressed through Federal, State, and potentially responsible parties' actions.

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Investigation and Cleanup Activities

Initial Actions

Immediate Actions: Immediate actions included the removal of an underground waste handling and solvent storage system and surrounding soil, installation and operation of groundwater extraction and treatment systems, and installation and operation of soil vapor extraction and treatment systems.

Cleanup Ongoing

Entire Site: In 1990, the EPA selected a remedy to address soil and groundwater contamination at the site. Approximately 40 cubic yards of soil have been removed and disposed of in an EPA-approved facility. Twenty-three soil vapor extraction wells have been built, along with a carbon adsorption treatment facility. Groundwater is being extracted, treated by air stripping, and discharged into Calabazas Creek. Monitoring of groundwater and soil will continue to verify the contaminants remain within health-based protection levels. The groundwater treatment systems are expected to continue to operate for several more years.

In 1986, the CRWQCB issued waste discharge requirements under the California Water Code that required Intersil, Inc. and Siemens Components to determine the extent of contamination in groundwater and soils. In 1989, the CRWQCB issued site cleanup requirements and approved the work plan and schedule for on- and off-site investigative activities.

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Cleanup Results to Date

Construction of all cleanup remedies has been completed. The removal of tanks and contaminated soil has reduced the potential for exposure to contaminated materials at the Intersil, Inc./Siemens Components site while groundwater cleanup continues.

The Fourth Five Year Review completed in September 2010 concluded that:
In the Off-Property Study Area, the vapor intrusion exposure pathway will be reevaluated in approximately one year following additional groundwater investigation. In order to make a protectiveness determination, an addendum to the 2010 Five Year Review is required. The Five-Year Review addendum should be completed by June 30, 2013.

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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.

Online information about the PRPs for the site is not yet available.

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Documents and Reports

Show details for Community InvolvementCommunity Involvement
Show details for Fact SheetsFact Sheets
Show details for Records of DecisionRecords of Decision
Show details for Technical DocumentsTechnical Documents

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Community Involvement

Public Meetings:

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Public Information Repositories

The public information repositories for the site are at the following locations:

Regional Water Quality Control Board,
San Francisco Bay Region,
1515 Clay Street, Ste 1400
Oakland, CA 94612

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

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EPA Site Manager
Melanie Morash
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Alejandro Diaz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Roger Papler
California Regional Water Quality Control Board
1515 Clay Street
Suite 1400
Oakland, CA 94612
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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