The EPA will test air quality in more than 200 homes and businesses to see whether soil contaminants are releasing vapors indoors.
The Environmental Protection Agency began taking air samples Monday from beneath basements in St. Louis Park to determine whether vapors from soil are infiltrating more than 200 homes and businesses.
The action comes after tests associated with groundwater contamination in the suburb discovered solvent fumes in shallow soil samples last year. State investigators, meanwhile, are zeroing in on the origins of the pollution.
"Some of the preliminary soil vapor samples that came back indicate that there may be as many as five different sources in the area," said Dave Scheer, hydrogeologist for the Minnesota Pollution Control Agency.
The contaminants of greatest concern, said EPA on-scene coordinator Sonia Vega, are trichloroethelene and perchloroethelene, solvents that have been used for decades as industrial degreasers, metal cleaners and dry-cleaning fluids.
The substances, known as volatile organic compounds, do not affect drinking water supplies in the St. Louis Park area, which are much deeper, according to state pollution officials.
Jim Kelly, health risk assessor for the Minnesota Department of Health, said that there are no indications so far that vapors have seeped into any homes or businesses, and tests of two schools done last month showed no contamination. But Kelly said that authorities need full assurance that even low levels of the chemicals are not getting into any dwellings.
"Long-term exposure [to these chemicals] could slightly increase the risk of certain adverse health effects, including sometimes cancer or effects on different organ systems such as the liver," Kelly said.
Vega said that 218 St. Louis Park property owners have given permission for the testing, five have refused, and about two dozen are waiting to see what the results are for their neighbors. The area being tested is on both sides of Hwy. 7 near Wooddale Avenue. Homes being tested have a hollow metal probe about the width of a pencil inserted into a hole drilled into their basement floors.
Vega said the lab will process about 50 samples a day during this week. If any homes or businesses show high levels of contaminants, lab staff will drive to those homes next week and collect air samples from different areas of the house.
Results of the tests will be available within a day or two to property owners, Vega said, and a preliminary summary of all of the tests will be released within a couple of weeks. If a house has a problem, she said, the remedy would be to install one or more collection pipes in the basement floor and use a small vacuum pump to direct the vapors outdoors.
The EPA Superfund is paying to test the St. Louis Park dwellings at a cost of about $1 million, Vega said, and will also assume the estimated $1,500 cost for homeowners, but not for businesses, if the properties need venting systems.
Once the agencies identify the sources of the pollution more precisely and confirm that data, Scheer said, they can also decide the best methods of cleanup, and whether current firms, former businesses, or the Superfund will pay the bill.
Tom Meersman • 612-673-7388