N.Y. Initiative Uncovers Need to Mitigate Some Vapor Intrusion

New York in 2005 reopened hundreds of pollution cases to determine whether new science could shed light on old cleanups, particularly with chemical vapors.

Three years later, the Department of Environmental Conservation (DEC) has made significant progress in tracking down and evaluating more than 400 sites, DEC Commissioner Pete Grannis said on March 9.

Thus far, 147 investigations have been completed. Of those, the state found that 19 required mitigation (ventilation systems) to alleviate vapors discovered on-site or in neighboring buildings, 46 required monitoring only, and 82 needed no further action (levels did not trigger mitigation or monitoring). In addition, mitigation has been determined necessary at 11 sites where investigations are still ongoing.

"Of all the states and (U.S.) Environmental Protection Agency regions, New York has the most systematic and proactive program for identifying and addressing vapor-intrusion sites," said Lenny Siegel, executive director, Center for Public Environmental Oversight, a group that has monitored vapor intrusion sites around the country.

"Vapor intrusion is an issue that wasn't even on the environmental map a generation ago," Grannis said. "But as the science has developed, New York has put together an aggressive and methodical plan for addressing potential vapor-intrusion sites. There is more work to be done and the state remains committed to attacking this issue."

"Vapor intrusion" refers to the process by which volatile chemicals move from a source below the ground surface (such as contaminated groundwater or contaminated soil) into the indoor air of overlying or adjacent buildings. Over the last decade, science about vapor intrusion has developed dramatically.

Vapors can enter buildings in two different ways. In rare cases, vapor intrusion is the result of groundwater contamination that enters basements and releases volatile chemicals into the indoor air. In most cases, vapor intrusion is caused by vapors from contaminated materials migrating through the soil directly into basements or foundation slabs.

DEC and the Department of Health (DOH) developed a joint strategy to evaluate the vapor intrusion pathway at all of the remedial sites that had been previously addressed through the Superfund, brownfields, or other clean-up programs in the state. That generated the list of 421 sites to be investigated. It should be noted that the 421 sites do not necessarily represent a confirmed vapor concern. Rather, New York State proactively decided to go back and review these sites to determine if there was a vapor concern.

For sites where mitigation is needed, this generally means installing a ventilation system inside buildings to move vapors to the outside where they disperse and are no longer a concern. This has occurred at 30 sites total -- 19 completed investigations, 11 ongoing.

In addition, Grannis pointed out that DEC now investigates for vapor intrusion as a regular part of its remediation projects. For more information, visit DEC's web page for vapor intrusion: http://www.dec.ny.gov/regulations/2588.html. For State Health Department information on vapor intrusion, go to: http://www.health.state.ny.us/environmental/indoors/vapor_intrusion/

A list of the sites is available at: http://www.dec.ny.gov/regulations/51715.html.

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