Overview of Intel Superfund Sites in Silicon Valley, CA

Background

Volatile organic compounds (VOCs), commonly used chemicals in the semiconductor industry, were first discovered in shallow ground water from industrial operations in the Silicon Valley in late 1979. About half of Silicon Valley's water supply comes from a deep ground water aquifer which is located several hundred feet below the valley floor under a thick clay layer in the vicinity of the Intel facilities; the other half comes from surface water. Although it is unlikely that the shallow ground water above this thick clay layer will be used as a drinking water source in the foreseeable future, protecting this ground water is considered important because it poses a potential threat to the underlying, valuable water supply source. Therefore, conservative drinking water cleanup standards are applied to this shallow water to protect the deeper water. In addition, all groundwater, no matter what depth, is considered by the State of California as a potential source of drinking water and must be restored to standards that allow the intended beneficial use (i.e., drinking water).

In early 1982, concern about widespread contamination in the area's shallow ground water led the California Regional Water Quality Control Board (Regional Water Board) to send chemical use questionnaires to over 2,000 facilities regarding the use of hazardous materials. Intel Corporation (Intel) was among the few questionnaire recipients that responded proactively by installing ground water monitoring wells adjacent to their underground chemical storage tanks. Intel also responded with a full inventory of all chemicals used in its operations.

Discovery and Aggressive Cleanup

Low levels (less than 1 part per million [ppm] or 1,000 parts per billion [ppb]) of VOCs were detected in ground water at two Intel facilities (Santa Clara 3 and Magnetics) and more significant levels were detected at a third facility (Mountain View Lot 3). Since these discoveries, Intel has very aggressively cleaned up these sites. By early 1986, all site source areas had been removed and ground water extraction and treatment systems (GWETS) had been installed and were operating to cleanup and contain residual VOCs in ground water.

National Priorities Listing

Although it was evident by the late 1980s that the VOC
contamination at Santa Clara 3 and Magnetics was minor,
these sites became federal Superfund sites on the National
Priority List (NPL) because they were among the handful of
sites that had sufficient data to be evaluated by the United
States Environmental Protection Agency (EPA) for
inclusion on the NPL. As shown on Figure 2, these two ground
water plumes are insignificant when compared to many other
ground water plumes in the immediate vicinity and in Silicon
Valley in general.

Original content reviewed and approved by United States Environmental Protection Agency (US EPA) Region 9 in 2007.

Site last updated: January 2014