State alerts Mpls. neighborhood about underground vapors

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."

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.

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.

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.

Kelly likened the situation to a discovery of TCE and perchlorethylene (PCE) in a St. Louis Park neighborhood of 270 properties in 2007. No imminent health risks were found, but remediation systems were installed in 41 homes.

Reaction in the Como area was guarded Thursday.

"I'll just wait to see what happens," resident Mike Portwood said. "I'd like to do a little research before I jump on the paranoia wagon."

Business owner Laura Curran said she didn't know about the neighborhood's history with General Mills or TCE. Her salon at Rollins and 15th Avenues SE. is at the corner of the testing area.

General Mills used the 6.5-acre site at 2010 E. Hennepin Av. as a technical center and laboratory for food research beginning in 1930, adding chemical research operations in 1947, according to the U.S. Environmental Protection Agency. Disposal of solvents started on the south end of the property in 1947 and continued until 1962.

"This was the state of understanding at that time, that waste solvents, if you put them in a hole, they would go away. They would go to this place called away," Neve said. "We learned decades later that there is no place called away."

Discovery of the contamination occurred in 1981 after the 1977 sale of the site to Henkel Corp., a Connecticut-based producer of laundry, home and beauty care products.

General Mills' cleanup efforts included the removal of contaminated soil on the property and groundwater testing in the neighborhood.

Staff writer Paul Walsh contributed to this report.

mckinney@startribune.com • 612-673-7329