Cleaning up river site may cost 3M $18 million

Cleaning up dangerous chemicals in the Mississippi River and at the 3M Co. plant in Cottage Grove will be more costly, complicated and time-consuming than cleaning up other contaminated areas in the east metro, according to a plan filed recently with the state. It will include dredging of the river to remove highly contaminated sediment in a cove and sandbar, 3M officials said, and will cost $12.5 to $18 million.

The cleanup also includes excavating soil at the chemical plant where wastes were buried years ago, and pumping out millions of gallons of polluted groundwater that flows into the Mississippi.

The chemicals include those formerly made by the company for non-stick cookware, stain-resistant fabrics and other products.

"I'm chagrined to find out that there was stuff buried at the 3M plant itself, because that was never part of our discussions with the company," said Sandy Shiely, Cottage Grove mayor. "I'm unhappy to find that out at this particular point."

Shiely said that the contamination does not threaten private or city wells.

Shiely also said she expects 3M to do everything possible to remove the contamination. "We don't want anything ... going into the river," she said.

3M spokesman Bill Nelson said that long-term effectiveness, not cost, is the most important factor in the cleanups.

The latest plan, called a feasibility study, was done by a 3M consultant and is the first time that costs have been estimated for the cleanup.

Sen. Katie Sieben, DFL-Newport, who represents the area, said that she has not been briefed on the cleanup plan but has many questions about it. "I wonder if the cleanup focuses on only the most contaminated areas, and where that leaves the rest of the area and the river," Sieben said. "If this is just 3M stating this is the worst part so this is what we're going to do, that doesn't seem to be in the public's best interest."

The report indicates that the combination of groundwater pumpout wells and soil and sediment excavation will protect the environment.

The main concerns are two perfluorochemicals (PFCs), which the company manufactured for more than half a century and were widely sold and used in Scotchgard, Teflon, firefighting foam and other coatings. The chemicals do not break down or degrade in the environment. At high levels they have been found to cause liver, developmental and other health problems in laboratory animals. 3M stopped manufacturing them in 2002.

Gary Krueger, Minnesota Pollution Control Agency Superfund project director, said that the agency will spend the next month evaluating the Cottage Grove plan, and could approve it, request modifications or more information, or reject it.

The MPCA required the plan as part of a legal agreement made with 3M last May that includes cleanups of PFCs in Oakdale, Lake Elmo, Woodbury and Cottage Grove.

The cove on the eastern edge of 3M's chemical plant receives wastewater and storm water from the chemical plant, as well as runoff from land. Its sediment includes "a black residue layer" from 2 inches to 2 feet in thickness, according to 3M's consultant, where samples showed concentrations of PFCs far higher than health officials consider acceptable.

John Linc Stine, director of the environmental health division for the Minnesota Department of Health, said that no communities near the Cottage Grove plant draw water from the river for drinking.

The cleanup plan calls for dredging the sediment from a river channel and sending about 2,200 truckloads of the contaminated muck to a licensed landfill.

The proposal also would install several high-capacity pumpout wells in a $3 million system to intercept PFC-contaminated groundwater that flows into the river.

In addition to MPCA approval, 3M will also need a permit from the Minnesota Department of Natural Resources and perhaps from the U.S. Army Corps of Engineers to dredge in the river, and to account for damage to wetlands and wildlife.

The proposed cleanup also offers three alternatives to cover or excavate soil that's highly contaminated with PFC wastes that were burned, buried or neutralized decades ago at the plant. The report estimates that an additional 3,000 to 3,200 truckloads of polluted soil will need to be excavated and removed, and that the entire cleanup project will require two or three construction seasons.

Nelson said that disposal in a lined landfill will protect the environment more than any other option.

Tom Meersman • 612-673-7388