Middlefield-Ellis-Whisman (MEW) EPA Superfund Study Area (or MEW Site) is comprised of three Superfund sites Mountain View California

Groundwater Contamination Map Toxic Plumes Map Source: The Chemical Legacy of Old Silicon Valley, NBC Bay Area, Map Editor Scott Pham 2019 https://www.nbcbayarea.com/on-air/as-seen-on/toxic-plumes_-the-dark-side-of-silicon-valley_bay-area/87485/

Envirostor State of California Link: “The EPA added this site to the National Priorities List (NPL) in 1991. This Superfund site is comprised of several former Fairchild Semiconductor Corp facilities spanning 56 acres in Mountain View. The Fairchild Semiconductor Corp – Mountain View site is one of three Superfund or NPL sites that are being cleaned up simultaneously. The other two Superfund sites are the Intel – Mountain View site and the Raytheon site. All three sites are located in the Middlefield-Ellis-Whisman (MEW) Study Area and are being addressed collectively as the MEW SIte. Site investigations at several of these facilities during 1981 and 1982 revealed extensive soil and groundwater contamination, primarily VOCs. Soil cleanup by soil vapor extraction, excavation, and aeration has been completed at all the MEW study area sites. Groundwater remediation is ongoing at the MEW Study Area.”

The contaminants which have been detected in soil and groundwater include trichloroethylene (TCE), trichloroethane (TCA), dichloroethylene (DCE) and chloroform.

The EPA website states:

Under EPA’s direction and oversight, the MEW Companies, including Fairchild Semiconductor Corp. and Schlumberger Technology Corp., implemented soil and groundwater cleanup programs that have included soil excavation and treatment, installation of four slurry walls, soil vapor extraction and treatment systems, and groundwater extraction and treatment systems. The soil cleanup by soil vapor extraction and excavation and aeration has been completed at all the former MEW facilities, including the former Fairchild facilities.

Groundwater cleanup will continue to operate for many decades in order to meet the trichloroethene (TCE) groundwater cleanup standard of 5 parts per billion. The MEW site groundwater remedy has removed over 76,000 pounds of contaminants, and has reduced contaminant concentrations throughout the multiple aquifer zones. The groundwater is not being used as a potable water supply, and there are no direct exposure pathways to the contaminated groundwater while groundwater cleanup continues.



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