The MEW Site is comprised of three National Priorities List (NPL) or Superfund sites. These sites include: (1) Fairchild Semiconductor Corp. – Mountain View Superfund site; (2) Raytheon Company Superfund site; and (3) Intel Corp. – Mountain View Superfund site; as well as several other facilities and portions of the former Naval Air Station (NAS) Moffett Field Superfund site. In or around the 1960s and 1970s, several manufacturing and industrial facilities operating in the MEW Site area, including semiconductor and other electronics manufacturing facilities and metal finishing facilities, leaked certain chemicals - primarily the chemical solvent trichloroethene (TCE) - into the soil and groundwater.

Dating back to the 1980s, many cleanup activities have been completed. After environmental investigations performed in the early 1980s, EPA issued a Record of Decision in 1989 which ultimately required the cleanup of soil and groundwater contamination. Soil contamination has been fully addressed but groundwater cleanup remains in progress, and will for many years. Groundwater occurs near the ground surface, ranging from depths as low as five (5) feet to twenty (2) feet below the surface.

Vapor Intrusion from groundwater into indoor air remains a possible risk in some locations. Later in 2010, based on EPA’s updated understanding of the way chemicals can potentially migrate from below the ground into the indoor air and after field investigations of the vapor intrusion pathway, EPA amended the 1989 Record of Decision to additionally require procedures to protect against the vapor intrusion pathway. The 2010 Record of Decision Amendment for the Vapor Intrusion Pathway described procedures to address both existing buildings and new buildings which, in summary, require vapor intrusion mitigation measures to be installed when air sampling results indicate the need.

The 2010 Record of Decision Amendment also established an Institutional Control program to address vapor intrusion risks. The institutional control program involves a layered approach to help assure that vapor intrusion risks are safely managed. The layered IC program involves: (1) use restrictions recorded in the land records for certain properties; (2) a cooperative permitting and environmental review approach between EPA and the City of Mountain View, and (3) land activity monitoring and tracking service sponsored by EPA. This Factsheet focuses on the second layer - the cooperative permitting and environmental review approach between EPA and the City of Mountain View.

For More Information: See USEPA Region 9 MEW Website

If you plan to develop property, perform excavations, renovate buildings, install utility lines, or engage in similar activities in Mountain View, you may need to USEPA review and approval before proceeding!

The review process process involves identifying your project location, completing a form describing the project, and possibly uploading documents. See the EPA Factsheet noted below for more details.

Image is an illustration of the Project Review Steps

While USEPA’s review might not trigger additional requirements, USEPA may require that your project include measures to protect against vapor intrusion, to protect workers from exposure to environmental contaminants, or to manage contaminated soil. In some cases, USEPA’s requirements might also call for the development of air sampling or soil management plans.

EPA FACTSHEET: EPA and City of Mountain View Coordinated Development Permit Review Process. This Factsheet explains the USEPA Project Review process, so you can most efficiently secure the review that USEPA requires. More specifically, this Factsheet describes: (1) why the USEPA Project Review process is needed, (2) the process for determining whether your activity triggers USEPA Project Review, (3) a USEPA Project Review Form to be submitted to USEPA, (4) additional information about the MEW Site and EPA contacts, and (5) USEPA points of contact.