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In November, Siegel published a nine-page, 2.1 megabyte document entitled “A Stakeholder’s Guide to Vapor Intrusion” that he describes this way:

Vapor intrusion refers to the migration of toxic vapors from the subsurface – that is, soil or groundwater – into homes, schools, and other overlying buildings. Though many substances, such as petroleum hydrocarbons and even elemental mercury, can intrude into buildings, sites that require a response usually contain chlorinated solvents – that is, volatile organic compounds (VOCs) such as trichloroethylene (TCE) and tetracholoroethylene (also known as perchloroethylene or PCE). TCE was widely used as a solvent in industries such as aerospace and electronics, but in recent years a relatively small number of businesses, primarily in metals processing, continue to use it. It is still found in consumer products such as gun cleaner and plastic cement. PCE is still widely used in dry-cleaning and automotive servicing. Toxic compounds found in petroleum products, such as benzene, toluene, ethylbenzene, and xylene (BTEX), may also pose a vapor intrusion risk, but they tend to pose less of a risk because they normally degrade near the ground surface as they come into contact with atmospheric oxygen.

While individual scientists and some states, such as Massachusetts and Colorado, have been addressing vapor intrusion since the since the 1990s, vapor intrusion started to become a standard part of contaminated-site response in 2001, when U.S. EPA’s Resource Conservation and Recovery Act program stipulated such an assessment for all Environmental Indicator human health decisions. In early 2002, the Denver Post brought national attention to the problem with a landmark series on vapor intrusion. Since then environmental regulatory agencies across the country – U.S. EPA and most states – have developed technical and policy guidance for investigating and mitigating toxic gas vapors. Thousands of officials and consultants attend frequent conferences and workshops on the subject. Vapor intrusion responses are often major local news stories. But many Americans who are potentially exposed via the vapor intrusion pathway do not know about it, and many who know about it do not understand the many complexities involved in assessing and responding to vapor intrusion.

The former Rocketdyne lab in the Simi Hills has 800,000 gallons of the goo in its spreading groundwater which, if currently-configured remediation systems were turned on, would take 80,000 years to suck up and clean.

An eastern chunk of the San Fernando Valley is a Superfund site in part because of TCE, a plume courtesy of the old Lockheed plant in Burbank that is spreading towards the Los Angeles River which is about to have $2 billion dropped on it to be “greened” by the city of LA.

Revelations of trichlorethylene’s increasing toxicity, and its fouling of the Santa Susana Field Laboratory’s groundwater, helped stop the development of Ahmanson Ranch in 2003. Our piece “Air Apparent” broke that story in the Ventura County Reporter. The 17-year-old project collapsed later that year.

The ranch was sold to the state in 2003 for open space by former banking giant Washington Mutual for $150 million, a pittance for a project worth $2 billion. In 2008, “WaMu” collapsed in the largest bank failure in U.S. history.

Even local history aside, developers, including municipal ones, shouldn’t take the threat of TCE lightly. The solvent, along with its by-product tetrachloroethylene (PCE), present a very real threat to structures already standing in Southern California.

In an upcoming investigative series EnviroReporter.com will expose just how extensive this pervasive problem already is in the most unlikely of places in the San Fernando Valley. Stay tuned and we’ll leave the window open for you.

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