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3M water filtration system gets Cottage Grove council approval

The Cottage Grove City Council recently approved a 3M site plan proposal to construct a filtration facility to clean chemically-tainted water before it is re-used or pumped into the Mississippi River.

Seven groundwater extraction wells pump millions of gallons of 3M-manufactured perfluorochemical-tainted water per day from underneath a former 3M dumpsite near the Woodbury-Cottage Grove border. From there it is piped six miles south to the 3M Cottage Grove facility. There, it flows untreated into the Mississippi River.

As part of a 2009 Minnesota Pollution Control decision related to cleanup of east metro PFC groundwater contamination, 3M has proposed to build a carbon filtration facility to clean that water before it is re-used at the Cottage Grove facility or piped into a river cove.

"This structure is very important to the environment," said City Engineer Jennifer Levitt.

Council members voted March 21 to grant a zoning ordinance variance to the project that was required because of the filtration facility's proposed metal exterior.

Construction of the filtration facility follows the substantial completion last year of a project that removed PFC-contaminated sediments from the river cove near the 3M plant.

In 2010, the company excavated roughly 10,000 cubic yards of polluted soil from former disposal pits at the Cottage Grove facility.