3M this month plans to begin the process of excavating thousands of cubic yards of soil from the 3M Cottage Grove manufacturing plant as part of a remedial effort to prevent further perfluorochemical contamination of the area's groundwater.
In 2006, the Minnesota Pollution Control Agency and 3M agreed to a settlement that called on the company to clean former dump sites where perfluorochemicals had been deposited, including the 3M Cottage Grove plant.
The company will dig out about 19,000 cubic yards of contaminated soil -- roughly the size of Park High School's eight tennis courts, city officials say -- from approximately two acres of land on the southeast corner of 3M's Cottage Grove property. It's part of what Jim Kotsmith, a manager in 3M's environmental group, said was a two-stem remediation that includes a system of wells installed for groundwater extraction and treatment in addition to removal of soil and, eventually, contaminated sediment from a Mississippi River cove.
The effort "basically captures and contains any PFCs" in the area, Kotsmith said, preventing the chemical from migrating south toward the Mississippi River.
PFCs are a group of manmade chemicals produced by 3M until early this decade for use in products like stain-resistant materials, non-stick cookware and firefighting foam. In 2006, the chemicals were detected at varying levels in area drinking water.
The Cottage Grove Planning Commission last week recommended city council approval of a grading permit that would OK the mountains of contaminated dirt that will be removed during the first step of the cleanup plan.
City Council members are expected to approve the permit at its Nov. 18 meeting. Work is planned to begin Nov. 30.
Soil dug from a pair of former disposal pits will be tested for chemical contamination. An estimated 12,000 cubic yards of dirt will be hauled off-site by trucks to either the SKB Environmental landfill in Rosemount, or the Environmental Quality Company's disposal waste treatment plant in Belleville, Mich.
The route trucks will take from southern Cottage Grove to the Rosemount facility follows Highway 61 north through Cottage Grove, St. Paul Park and Newport, onto westbound Interstate 494 into South St. Paul and then south on state Highway 52 through Inver Grove Heights and into Rosemount.
Future steps in the cleanup include:
- Final approval of the remedial action plan by the Minnesota Pollution Control agency (February 2010)
- Further disposal site excavation (2010)
- Groundwater well installation (2010)
- Construction of water treatment building (2010-2011)
- Removal of sediment from Mississippi River cove that was discharge point for contaminated water into the river (2011)
3M spokesman Bill Nelson declined to reveal the expected cost of the PFC cleanup.
"3M is devoting the adequate resources to do the job right," he said last week.