|By Libor Jany, Star Tribune (Minneapolis)|
|McClatchy-Tribune Information Services|
Like a detective working an old, unsolved case by revisiting where the crime occurred, Small and a team of investigators regularly return to
"Site assessment is basically Superfund, before Superfund," said Small, a hydrogeologist by training.
The MPCA, which often works in conjunction with the
The agency cleared 68 contamination cases, totaling over
Most cases, Small says, are cut and dried.
"They find some hydrocarbon fuels -- that's generally what you would expect at a gas station. But, say they find a bunch of perchlorethylene ... it's a commonly-used dry-cleaning solvent and a commonly-used metal finishing degreaser.
"And, so that's not something you would expect to see at a gas station. So they would report that and say there would appear to be an off-site source because this is a gas station and it's always been a gas station. They never serviced vehicles so there's no reason for them to have chlorinated solvents on site."
MPCA investigators have also helped unravel some of the state's most baffling environmental cold cases.
"It starts with a lot of desk work," said
In 2002, the agency began looking into the
But a subsequent MPCA investigation turned up new evidence that the source of the contamination was in fact a since-defunct metal fabrication shop that had been dumping trichloroethene (TCE), a chemical carcinogen that was once used as a degreaser, into the soil near the site.
Chemicals eventually seeped through the ground and into wells that supplied the neighboring city of
"In 2002, after many years of investigation at the
"The review involved examining historical aerial photographs, telephone directories, insurance maps, and conducting interviews with former local officials."
Residents in the affected communities with private wells were required to install carbon filters to strain out the chemical. In the meantime, the MPCA has continued its monitoring efforts of the contaminated areas.
Depending on the type of chemicals that were dumped -- and over how long a period -- the cost of proper cleanup can reach millions of dollars, officials say, which is why sorting out responsibility and liability can also be sticky business, Small said.
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