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Case Summary: Settlement Reached at Middlefield-Ellis-Whisman (MEW) Study Area to Address TCE Contamination

On December 21, 2011, a consent decree amendment between the U.S. Environmental Protection Agency (EPA), Department of Justice (DOJ), Intel Corporation, and Raytheon Company was filed with U.S. District Court for the District of Northern California. Under this settlement and a related administrative order with the same scope of work, Intel Corporation, Raytheon Company, and several other parties will address human health risks caused by potential vapor intrusion of trichloroethene (TCE) into approximately 60 commercial and residential buildings in Mountain View, Calif. The parties will also ensure future buildings in the MEW vapor intrusion study area are designed to prevent vapor intrusion of site contamination above site cleanup levels. The cleanup, which supplements ongoing soil and groundwater cleanup work at MEW, is one of the largest Superfund vapor intrusion cleanups to date.

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Information about the Companies

Founded in 1968, Intel Corporation is a multinational semiconductor chip maker headquartered in Santa Clara, Calif. Founded in 1922, Raytheon Company is a major American defense contractor and industrial corporation with core manufacturing concentrations in weapons and military and commercial electronics. As part of their electronics manufacturing operations, both Intel and Raytheon handled a wide variety of solvents to clean and degrease parts and equipment, and they stored and disposed of these solvents at their respective facilities.

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Information about the Middlefield-Ellis-Whisman (MEW) Superfund Study Area

Located in Mountain View, Calif., the Middlefield-Ellis-Whisman (MEW) Superfund Site was home to several manufacturing and industrial facilities, including facilities for semiconductor and other electronics manufacturing and metal finishing. While in operation, these facilities required the storage, handling, and use of a variety of chemicals, including volatile organic compounds (VOCs).

The MEW Superfund Study Area is comprised of three listed National Priorities List (NPL) or Superfund sites:

The "MEW Superfund Study Area" itself is not listed on the National Priorities List (NPL). More information on the MEW Study Area.

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Pollutants and Environmental Effects

The primary contaminants of concern at the MEW Site are trichloroethylene (TCE) and other VOCs in soil and groundwater. The primary exposure pathway addressed in this action is the potential migration from those sources to indoor air in overlying buildings through the vapor intrusion pathway. Vapor intrusion is the migration of volatile chemicals from contaminated groundwater or soil into overlying building. During operations from the 1960s until the 1980s, some of these chemicals leaked or were otherwise released into the ground, impacting soil and groundwater. In 1981 and 1982, investigations in the area of these facilities indicated that significant levels of contaminants had reached the soil and groundwater. More information is available from the Agency's vapor intrusion and the Superfund program website.

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Overview of the Consent Decree Amendment

Under a previous settlement, Intel and Raytheon have been conducting soil and groundwater cleanup at the MEW Site for almost two decades. Eight other parties are also required to conduct the soil and groundwater cleanup under an EPA order.

Based on indoor air sampling conducted beginning in 2003, EPA determined that the original cleanup plan did not adequately protect human health because it did not address exposure to contaminants through the vapor intrusion pathway. Under the MEW CD Amendment, Intel and Raytheon, along with the parties subject to the administrative order, will perform the remedy to address the vapor instruction pathway that is potentially causing exposure to site contamination in indoor air in buildings overlying the site’s contaminated shallow groundwater aquifer.

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Comment Period

The MEW Amended CD was filed with the U.S. District Court for the District of Northern California on December 21, 2011. Following a 30-day public comment period, the federal district court approved and entered the CD Amendment on March 6, 2012.

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Contact Information

For more information contact:

Bethany Dreyfus
Assistant Regional Counsel
U.S. Environmental Protection Agency
Region 9
75 Hawthorne Street
San Francisco, California 94105

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