Special unit takes on environmental cold cases

  • Article by: LIBOR JANY , Star Tribune
  • Updated: July 26, 2014 - 2:00 PM

MPCA’s site assessment division searches for how contamination got into local water supplies.

For Greg Small, a project manager with the site assessment division of the Minnesota Pollution Control Agency (MPCA), aging factories and abandoned industrial sites take on the air of a crime scene.

Like a detective working an old, unsolved case by revisiting where the crime occurred, Small and a team of investigators regularly return to Washington County’s Baytown Township groundwater contamination site, one of several hundred “brownfield” sites across Minnesota that have been contaminated with toxic chemicals.

“Site assessment is basically Superfund, before Superfund,” said Small, a hydrogeologist by training.

The MPCA, which often works in conjunction with the Minnesota Department of Health, was investigating 107 sites during the second quarter of 2014, with an ever-increasing backlog waiting to be pursued, officials said.

The agency cleared 68 contamination cases, totaling over $735,000 in penalties, in that quarter, officials said.

Most cases, Small says, are cut and dried.

“It’s Joe Blow’s gas station. They want to sell it. The buyer wants to know what contamination is present so that he can limit his liability. They’re looking for gasoline, but they’re also looking for other volatile organic chemicals,” Small said as he sat in his supervisor’s office on a recent morning.

“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 Hans Neve, a supervisor in the MPCA’s site remediation section.

In 2002, the agency began looking into the Baytown Township case, involving groundwater pollution at a small market and gas station in Lake Elmo. The pollution was long believed to have originated from the nearby Lake Elmo Airport, leaving the Metropolitan Airports Commission (MAC) on the hook for its cleanup.

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 Bayport and Baytown and West Lakeland townships with drinking water.

“In 2002, after many years of investigation at the Lake Elmo Airport failed to identify a significant source of TCE, the MAC asked their consultant, Conestoga-Rovers & Associates, to review historical records for the City of Lake Elmo, located ‘upstream’ in terms of groundwater flow,” a 2009 Health Department report said.

“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.

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