The U.S. Environmental Protection Agency (EPA) got rid of the contaminated soil in Mountain View and extracted the poisonous vapors, but the toxic groundwater was going to take “many decades” to clean up while they constructed slurry walls and water treatment systems.

Time isn’t always kind.

The toxic plume of water underground in Silicon Valley, known as the MEW Superfund sites, is apparently considerably larger than previously thought, much to the distress of nearby neighborhoods and workers in Google-occupied buildings.

The Middlefield-Ellis-Whisman (MEW) Superfund Study Area is actually three superfund operations tending to the past sins of Raytheon, Intel, Fairchild Semiconductor, the U.S. Navy and NASA. The sites are clustered together in Mountain View, extending from Moffet Field along the bay west through what was once the launching pad for the semi-conductor industry.

Those companies either dumped or allowed to leach into the soil some nasty chemicals, including trichloroethene (TCE) and vinyl chloride during the 1960s and ‘70s. TCE is a cleaning solvent that causes heart deformities in fetuses, and cancer. It was used by both the military and the tech industry and is the dominant problematic chemical lurking under ground.

Investigations begun in 1981 by the EPA led to a consent decree in 1992 to clean it up.

NBC began to ask questions about the MEW in April and shortly thereafter the Cancer Prevention Institute of California (CPIC) conducted its own study of decades of health data. The institute found neighborhoods outside the MEW with “hotspots” of non-Hodgkin lymphoma.

The EPA started testing the air and water around the MEW and began notifying people and businesses they had a problem with high concentrations of TCE leaching from the ground intro structures. Buildings occupied by Google and others nearby registered TCE levels considered 26 times the acceptable level.   

Contraptions to pump air out of homes and commercial buildings are pumping away and people are being reassured it’s safe to be there. Now. But according to NBC, the EPA could not say how long the plume had been there.

It could have been decades.

–Ken Broder

To Learn More:

Concern For Mountain View Toxic Plume Expanded (by Stephen Stock and David Paredes, NBC)

Notice to Homeowners and Residents in the Residential Area (U.S. Environmental Protection Agency) (pdf)

Air-Sampling Results from Google-Occupied Buildings (Center for Public Environmental Oversight) (pdf)

The $24 Million Vapor Intrusion Remedy (by Bill Wagner, CommonGround)