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3M Cottage Grove Site Cleanup Plan

Wednesday, May 20, 2009 - 10:00am

Minnesota Pollution Control Agency

Notice for Public Comment

3M Cottage Grove Site Cleanup Plan

The MPCA invites the public to comment on a proposed cleanup plan for contamination related to perfluorinated chemicals at the 3M Cottage Grove Site, in Cottage Grove, Minn. The public comment period begins May 20, 2009 and closes June 19, 2009. A public meeting will be held in Cottage Grove on May 27 (see below for details).

The 3M Cottage Grove Site is located along State Highway 61 in Cottage Grove, at Innovation Road. The site houses a large research and manufacturing complex at which 3M has made a variety of products since the 1940s.

The site was placed on the State Superfund list in 1984 due to soil and groundwater contamination from volatile organic compounds (VOCs, typically solvents). 3M completed site investigations and cleanup actions in the 1990s to address VOCs. Since 2004, 3M has been working with the MPCA to assess the presence and extent of PFCs in soils and groundwater at the site. Wastes containing PFCs were disposed of at the site in a number of different disposal pit locations. PFCs are also found in sediments in a cove at the foot of the bluff along the Mississippi River.

3M installed a groundwater pump-out system on the site in the 1980s to control migration of VOCs toward the Mississippi River. The system continues to operate today, pumping groundwater back into 3M's manufacturing facility on the site to augment cooling and process water, after which it is discharged with other treated wastewater via a flow channel to the Mississippi River.

After analyzing various options for long-term remedies for PFC contamination at the site, 3M completed a Feasibility Study and submitted it to the MPCA on March 13, 2008, followed by requested amendments on January 6, 2009. The MPCA evaluated the studies and has selected its preferred remedy. The preferred alternative is now available for public comment.

The MPCA recommends implementing the following remedies at the Cottage Grove site:

• Institutional controls/deed restrictions, site access controls, and long-term groundwater monitoring

• Enhanced groundwater recovery with treatment to remove PFCs prior to discharge

• Stabilize flow channel to East Cove and remove PFC-containing sediments throughout the cove

• Remove portions of sandbar at cove outlet

• Remove concrete basin previously used for disposal in Disposal Area D1 and remove additional overlying soils in that area

• Remove PFC-contaminated soils in Disposal Areas D1, D2 and D9 which exceed Industrial Soil Reference Values for PFOA and/or PFOS

• Transport excavated soil, sediments and material to engineered long-term containment cell at SKB Industrial Landfill, Rosemount, Minn. All excavated material will be disposed off-site.

MPCA staff believes this combination best meets the cleanup goals for the site. The selected remedies will take an estimated three years to complete.

The Feasibility Study analyzing these and other possible cleanup remedies for the site is available at the MPCA's St. Paul office, 520 Lafayette Road, St. Paul, MN 55155, or on the agency's Web site at www.pca.state.mn.us/cleanup/pfc/pfcsites.html.

Comments regarding the proposed remedy must be in writing and must be received at the MPCA by close of business on June 19th, 2009. The MPCA will also present the proposed remedy at a public informational meeting at 7:00 p.m. on May 27th, 2009, at the Cottage Grove City Offices, 7516 80th Street South, Cottage Grove. MPCA staff will be available for questions in an informal open-house format for one hour prior to the meeting.

This public meeting will only address the proposed PFC cleanup plan for the 3M Cottage Grove Site. No other 3M-related environmental issues will be discussed.

After close of the comment period, the MPCA will review all comments and approve, modify, or reject the proposed remedy, which will be outlined in a final decision document signed by the MPCA Commissioner. Written comments should be directed to:

Gary Krueger

Minnesota Pollution Control Agency

Remediation Division

520 Lafayette Road North

St. Paul, MN 55155-4194

Gary.krueger@pca.state.mn.us

(Published in the South Washington County Bulletin on Wednesday, May 20, 2009.)