Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Intel Corp. (Santa Clara 3)
EPA #: CAT000612184
County: Santa Clara
City: Santa Clara
Congressional District: 15
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 10/15/84
Final Date: 06/10/86
The Intel Corp. (Santa Clara 3) facility performed quality control of chemicals and tests microprocessors at this four-acre property. Volatile organic compounds (VOCs) are present in the groundwater in the shallow aquifer zone; however the source of the groundwater contamination was never found on the property. This site is one of 28 EPA National Priorities List (NPL) or Superfund sites in the South San Francisco Bay Area (South Bay). Generally, a variety of toxic chemicals, primarily chlorinated organic solvents, such as trichloroethene (TCE) were used at the South Bay sites, and were subsequently released to the soil and groundwater. As a result, the groundwater basin has been contaminated .
Contaminants and Risks
Groundwater has been contaminated with volatile organic compounds (VOCs), primarily trichloroethene (TCE). Based on available information, this site is not considered to be of public health concern because of the apparent absence of people being exposed to hazardous substances. However, people could face a health risk if they accidentally ingest or come into direct contact with contaminated water.
Who is Involved
This site is being addressed through Federal, State, and potentially responsible parties' (PRP) actions. The United States Environmental Protection Agency (EPA) has been the lead agency for this site since August 2006. Prior to that, the State of California, through the Bay Area Regional Water Quality Control Board (RWQCB) was the lead agency.
In 1985, the potentially responsible party installed and began operating a groundwater extraction and treatment system until 1993.
In 1990, under EPA oversight, Intel completed an investigation of the nature and extent of contamination at the site. The remedy selected by the EPA in 1990 included: groundwater extraction and treatment with an expanded granular activated carbon system to treat the groundwater, discharging the treated groundwater to San Tomas Aquino Creek; monitoring groundwater; and performing a demonstration project to evaluate various groundwater pumping strategies for cleaning up residual VOCs left behind in aquifer material.
Several pumping scenarios were evaluated in an effort to optimize the efficiency of the groundwater extraction and treatment system and in 1991 Intel implemented a cyclic pumping strategy until July 1993. VOC concentrations were leveling off, and the groundwater extraction and treatment system was no longer effective at recovering significant quantities of contaminants. Therefore, the groundwater extraction was turned off in July 1993, and natural attenuation monitoring began.
During the period of groundwater extraction, approximately 45 million gallons of groundwater were extracted and treated. Approximately 28 pounds of TCE, the primary contaminant, had been removed. The majority of contaminant mass was removed during the first few years of operation of the groundwater extraction system. Deed restrictions for use of the property were put into place in 1992 and modified in 2008. The deed restriction prohibits the drilling of groundwater wells for domestic or industrial use and restricts the land use.
In 2006, Intel prepared a Focused Feasibility Study (FFS) to compare the ROD-selected groundwater extraction and treatment remedy to other remedial alternatives, such as in-situ remediation technologies. The purpose of the FFS was to determine what other technologies can be implemented in order to achieve more effective and efficient cleanup of the remaining low- level groundwater contamination. Based on the findings of the FFS, Intel performed an in-situ chemical oxidation treatability study at the Site. Intel injected a controlled subsurface oxidizing reaction that reduces VOC concentrations. The alternative technology did not reduce the remaining contaminant concentrations to achieve the ROD cleanup levels.
In December 2007, Intel prepared a Chemical Oxidation and Technical Impracticability Evaluation Report. This report stated that groundwater restoration at the Site would not likely occur under further pumping or non-pumping conditions in a reasonable timeframe, due to the complex site geology and matrix diffusion, However, since 2007 all but one well have achieved the cleanup goals.
In 2010, EPA amended the ROD to use Monitored Natural Attenuation to address the remaining low levels of TCE in the groundwater. MNA involves letting naturally occurring physical, chemical, and/or biological processes reduce the amount of contaminants in groundwater.
In March 2010, Intel conducted indoor air sampling to evaluate whether vapor intrusion could expose future building occupants to Site contaminants. There was one detection of vinyl chloride and one detection of TCE, but both were well below EPA Regional Screening Levels (RSLs) for industrial indoor air.
June 2011: EPA completed a fourth Five Year Review for the site and determined that the remedy is protective of human health and the environment. The groundwater contamination has been reduced to below drinking water standards in all but a very limited area; the remedy is expected to achieve drinking water standards site-wide and be protective for the long-term. Any groundwater exposure pathway that could result in unacceptable risks is currently being controlled through a land use covenant that restricts soil excavation and certain types of property development, and prohibits the drilling of groundwater wells.
2014-15: Intel conducted a long-term pumping test to reduce the residual TCE concentrations in the groundwater between August 2014 and April 2015. However, there were no significant sustainable concentration decreases resulting from these tests.
Late 2016: EPA completed a fifth Five Year Review for the site and determined that the remedy is protective of human health and the environment in August 2016. Additionally, a pilot test began to determine if the injecting activated carbon would reduce the remaining TCE in grounwater, to below site cleanup goals. The test and evaluation of the pilot will continue through 2017.
Cleanup Results to Date
The construction of all cleanup remedies was completed in 1992. The groundwater extraction and treatment system was discontinued, and monitored natural attenuation commenced in 1994. The groundwater extraction and treatment system was effective at removing VOCs from the groundwater, therefore very low levels of groundwater contamination remain.
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 named PRPs for this site include:
Documents and Reports
Public Information Repositories
The public information repositories for the site are at the following locations:
Santa Clara City Library
2635 Homestead Road
Santa Clara, CA95051
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
1515 Clay Street
Oakland, CA 94612
After Hours (Emergency Response)