Year | Type | Name | Sampled | TCE Result | |
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WhatsDownMEW provides publicly available information related to the MEW Site in easily navigable map layers. The maps shows USEPA-defined boundaries, groundwater data, and environmental reports associated with discrete properties. Selecting the map layers turns them on and off. When active, selecting mapped information brings users to additional details about the area boundary, the data, or the reports.
Terradex is pleased to provide WhatsDownMEW for informational purposes. The data presented on the site was gathered from a government sources. While Terradex has taken care to present the data and information accurately, the data and information provided may include inaccuracies and may be incomplete or out of date.
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Vapor Intrusion Study Area
The Vapor Intrusion Study Area marks the area where USEPA determined, in a 2010-published Record of Decision, that there are potential health risks associated with long-term exposure to trichloroethene (TCE) and other MEW Site chemicals of concern through the vapor intrusion pathway in existing and future buildings overlying the shallow groundwater contamination at the MEW Site.
Within the Vapor Intrusion Study Area, USEPA's 2010-published Record of Decision provided a remedy designed to protect the health of current and future occupants, including workers and residents, of buildings overlying the Site’s shallow subsurface TCE contamination.
EPA’s selected remedy addresses existing buildings and the construction of new buildings., as well as setting future restrictions or requirements, all of which intend to protect against exposure associated with the vapor intrusion pathway.
See EPA's 2010-Published Record of Decision.
Operable Unit 3
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USEPA Project Review Area
The Project Permit Review Area is an area defined by USEPA, providing the boundaries inside of which USEPA review may be needed as part of the process of securing City of Mountain View permits for activities such as: excavations, renovate buildings, install utility lines, or engage in similar activities.
This boundary was set by USEPA based on the potential risk due to below-ground contamination that could be exacerbated or otherwise cause adverse impacts in some cases.
Monitoring Wells/Sample Points
Monitoring Wells and additional Sample Points have been sampled in and around the MEW Study Area for the purpose of measuring groundwater quality, and helping to define the boundaries of any chemicals of concern.
Monitoring Wells are permanent wells constructed for the purpose of collecting groundwater samples. All Monitoring Wells shown on WhatsDownMEW collect groundwater samples at depths ranging from approximately 5 to 25 feet below the ground surface.
Sample Points mark areas where "grab samples" have been collected from the shallow groundwater without the use of a Monitoring Well.
Parcel Boundary
Parcel Boundaries, and associated addresses and assessor parcel numbers, depict information made publicly available by the County of Santa Clara. WhatsDown refreshes Parcel Boundary information frequently. See About the Data/Data Dictionary for refresh information.
Building Footprint - Property Specific Environmental Reports
During the environmental response action in this area, environmental studies, collection of data, and or remedial action has occurred at various select properties. Properties marked as having Property-Specific Environmental Reports provide access to environmental-related reports and other information. The available information provides details about sampling results, the environmental and human health risks, if any, at the property and, in some cases, future restrictions on use or future obligations related to use of the property.
Data | Description | Source of Data | Refresh Date |
---|---|---|---|
Vapor Intrusion Study Area | Location polygon depicting area boundary. | USEPA | January 22, 2018 |
Operable Unit 3 | Location polygon depicting area boundary. | USEPA | January 22, 2018 |
USEPA Project Review Area | Location polygon depicting area boundary. | USEPA | January 22, 2018 |
Monitoring Wells/Sample Points Location | Well and Sample Locations | USEPA | January 22, 2018 |
Monitoring Well/Sample Point Results | Water Quality Data. | USEPA | January 22, 2018 |
Parcel Boundaries | Map layer and select attributes for property parcels. | County Assessor Public Record | January 22, 2018 |
Parcel Attributes | Location polygon depicting area boundary. | County Assessor Public Record | January 22, 2018 |
Building Footprint - Property-Specific Environmental Reports Locations | Location polygon based on address and/or lat and long where property-specific environmental reports impact. | USEPA | January 22, 2018 |
Environmental Reports | Professional reports addressing environmental conditions at discrete locations. | USEPA | January 22, 2018 |
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.