Two hundred and seventy properties near the intersection of Highway 7 and Wooddale Avenue in St. Louis Park will be tested for two contaminants. One is perchloroethylene (PCE) and the other is trichloroethylene (TCE). These are man-made chemicals commonly used to dry clean fabrics and degrease metal parts. They're also known as volatile organic compounds or VOCs.
Most of the properties scheduled for testing are residential.
At this time, no agency has identified a particular source of contamination or identified actual evidence of vapor intrusion in these areas, only the potential. The investigation is a precautionary step to identify and prevent any potential chronic health problems that could come with long term exposure, according to James Kelly with the Minnesota Department of Health.
"We really have no evidence that levels would be such that it would be a short term risk or immediate concern. It's really just trying to eliminate this as a source of low level risk over a long period of time," he said.
Kelly said it's premature to advise residents to take any kind of precautionary steps.
The MPCA learned about the possibility of these vapor contaminations when the city of Edina asked the agency to test water from one of its municipal wells. Water sample results showed VOC contaminants. That well has been shut down since and the MPCA decided it should do some further testing in monitoring wells and soil in St. Louis Park. Preliminary testing started in February 2006 and continued through this September. The agency realized it would need help from the EPA, according to MPCA commissioner Brad Moore.
"The reason we're using EPA in this is because they have a lot of expertise in terms of vapor chemicals moving through soils. And it's an emerging issue across the nation and they have the resources to look at how these issues are addressed," he said.
Officials say this is a situation that will be easily remedied if they find vapors are making their way into homes and businesses. The fix for this contamination would be the same for radon, says the health department's James Kelly. He said Minnesota has a long history of dealing with radon because it's naturally-occurring.
"Fortunately we've developed an industry that's capable of providing mitigation and actually eliminate that problem. This is actually the same situation only the source of the vapors is man-made instead of naturally occurring but the systems have a great track record and they work well, they are very simple and easy to install," he said.
The investigating agencies say winter is the best time to test these homes and businesses for vapors because the buildings are closed and vapors are more easily detectable. Investigators will need permission from residents and business owners to access their properties and conduct the testing. Public meetings on the investigation will be held later this month.