Fumes could enter Minneapolis homes from the soil, once contaminated with a solvent from an old General Mills lab.
Residents and businesses in a southeast Minneapolis neighborhood have been alerted to potentially harmful vapors that may be entering buildings from the soil, a remnant of decades-old contamination from a defunct General Mills facility.
State health and pollution control officials are seeking owners’ permission to test the soil beneath 200 buildings in the Como neighborhood for trichloroethylene, or TCE, which can lead to cancer or immune-system disorders if people are exposed to high levels for long periods.
Recent testing of soil gas below streets and sidewalks in the neighborhood found levels of TCE that do not suggest imminent health risks but were sufficient to require investigation of the ground beneath the buildings, said Hans Neve, a supervisor with the Minnesota Pollution Control Agency’s (MPCA) Superfund program.
“We know the contamination is in the vapor under the ground,” he said. “Is it getting into the homes? That’s the question we need to answer.”
Contamination dates from ’40s
The presence of TCE in the neighborhood wasn’t a surprise; General Mills had used the compound as an industrial degreasing solvent at a plant on the north edge of the area from the 1940s until the 1960s, and had dumped thousands of gallons of solvent waste at a pit on the property.
Groundwater in the area had been pumped and treated to remove traces of toxic TCE, under the federal Superfund program, for 25 years until September 2010, when the MPCA concluded that the groundwater quality had stabilized.
Recent scientific discoveries that TCE can also contaminate soil gas just below the surface led to additional tests of the ground below streets and sidewalks.
Community meetings have been scheduled to answer questions for property owners in the area, which consists of about 20 blocks in the vicinity of Van Cleve Park.
Testing would consist of drilling small holes in the basements of affected buildings to determine whether contaminated vapor is “intruding” upward into the buildings.
Remediation would in most cases involve the same systems that are commonly used to remove radon gas from homes — at a typical cost of $1,000 to $2,000, which General Mills would pay. The company will also cover the cost of tests, about $1,000 per home.
“We predate the state, we predate the city of Minneapolis,” General Mills spokesman Tom Forsythe said. “We’re going to address this issue in our hometown, and we’re going to make it right.”
Health officials noted there is no risk of contamination to local drinking water, which doesn’t come from groundwater wells.
People at the greatest risk from exposure to odorless TCE vapors include pregnant women, young children and people with weakened immune systems. Research has linked substantial TCE exposure to cancers of the kidney, liver and lymph nodes.
“The more that someone’s exposed and the longer they’re exposed, the higher their risk,” said Jim Kelly, a manager at the Minnesota Department of Health.
In this case, health officials “can’t really quantify whether anyone is at risk” until the buildings are tested, Kelly said. There is no evidence of a cancer cluster or higher rates of disease in the neighborhood. Testing could start Nov. 18.
Guarded reaction in Como
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