Study planned to measure dry-cleaning fluid vapor levels in Bozeman homes

published on Thursday, November 5, 2009 9:36 AM MST

By AMANDA RICKER Chronicle Staff Writer

The city of Bozeman and CVS Pharmacy plan to study whether vapors of a dry-cleaning fluid suspected of causing cancer have migrated from a Superfund site at the Hastings shopping center into nearby homes.

But city officials and environmental experts say residents shouldn't be alarmed about the indoor air tests for PCE, also known as perc. The study is part of ongoing testing at the West Main Street site.

"When we started to do this testing, there was nothing to show that it was a problem that (the PCE) was there," Bozeman Public Works Director Debbie Arkell said Wednesday. "If you go home, and bring a sack of dry-cleaned clothes, you're going to breathe more PCE than what we're testing."

PCE is common in homes, coming from household cleaning products, paper coatings and printing inks, as well as dry-cleaned items. Residences near businesses that use PCE, such as automobile repair shops and dry cleaners, often contain traces of PCE, too.

"PCE really is ubiquitous in the environment," said Mike Ellerd, project manager at ATC Associates, one of two environmental consulting firms conducting the study. "It's very commonly found in residences throughout the U.S."

Any PCE that migrated into peoples' homes from the Superfund site would not reach levels high enough to make people sick, said Scott Dwyer, senior toxicologist with Kleinfelder, the other environmental consulting company hired to conduct the study.

"If I was living in that neighborhood, knowing what I know ... I wouldn't be worried, but I would want additional testing to be done so we could understand the scope," Dwyer said.

But the indoor air study is warranted because a previous study this summer found that PCE levels in the area exceeded the screening level set by the Montana Department of Environmental Quality.

The summer study, which tested soil vapor, found PCE levels that ranged from 2.4 to 4,100 micrograms per cubic meter, Ellerd said. DEQ requires further testing in areas where PCE levels exceed 4.1 micrograms per cubic meter. The samples were taken from city streets. The highest soil vapor level was found on Beall Street near the Superfund site.

Aimee Reynolds, a vapor intrusion specialist at DEQ, said though 4,100 micrograms per cubic meter sounds high, it doesn't mean that there's anything wrong with the air in residences.

However, if levels of PCE inside area homes are determined to exceed DEQ standards, the city and CVS could be required to take steps to mitigate the site.

About 10 percent of area structures are expected to be tested, said Mike Ellerd, project manager at ATC Associates, the other environmental consulting company hired to conduct the study.

The area stretches from Beall Street north to Durston Avenue and from 18th Avenue east to 15th Avenue.

Residents will be asked for permission before their homes are tested.

Both indoor air and "sub-slab" samples from the building's foundation are expected to be taken, Ellerd said.

The air is tested using a canister about the size of a milk jug that is placed in a resident's homes for about 24 hours, he said.

"Sub-slab" vapor samples are taken by drilling a small hole in the foundation.

Samples are expected to be collected in January and February and the results should be available shortly thereafter.

The city and CVS have seen no evidence to suggest that PCE concentrations found in residences would exceed normal, Ellerd and Dwyer said.

PCE was discovered at the shopping center in 1989. The contamination was linked to a former dry cleaning business at the center that had disposed PCE into the sewer system.

Once the PCE was found, septic and sewer systems were replaced or removed, during which some soil was removed as well. Additional PCE was removed in the mid-1990s. And, groundwater sampling is conducted on a semi-annual basis to monitor PCE concentrations in the aquifer.

The city and CVS share joint responsibility for cleanup of the site, called the Bozeman Solvent Site. CVS assumed responsibility for the site in 2006 as part of its acquisition of the Osco Drug chain.

Amanda Ricker can be reached at aricker@dailychronicle.com or 582-2628.

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