The Minnesota Pollution Control Agency (MPCA) is seeking public comment on a proposed plan to clean up contamination related to perfluorochemicals (PFCs) at the 3M Oakdale site in Oakdale.
A public meeting on the proposed cleanup will be at 7 p.m. Thursday, May 22, at the Oakdale City Offices.
The public comment period for the proposed plan ends June 20.
The site is along State Highway 5, just west of Interstate 694. It consists of three old dumps at which the St. Paul-based 3M Company legally disposed of manufacturing wastes during the late 1940s and '50s. In the 1980s, the site was placed on the state and federal Superfund lists due to contamination from solvents in the wastes.
As part of the earlier cleanup, 3M installed a ground-water pump-out system on the site in the 1980s to control migration of solvents in groundwater. The system continues to operate today, removing VOCs from the groundwater and discharging to the sanitary sewer.
Since 2005, 3M has been working under MPCA oversight to investigate the extent of PFCs in soils and groundwater at and near the site. The site is one of the four suspected as a source of the PFC ground-water contamination in the east metro area that was discovered in 2004.
3M completed a feasibility study of various options for cleaning up the PFCs at the site and submitted it to the MPCA on Jan. 28. After evaluating the options, the MPCA has selected its preferred alternative.
The MPCA recommends upgrading the existing pump-out system so that it better captures PFCs in groundwater at the site.
The discharge from the pump-out would be run through an air stripper to remove volatile compounds, then filtered with activated carbon to remove PFCs and discharged to the sanitary sewer.
In addition, 3M would excavate soil on about 55 acres of the site known as the Abresch area, which straddles Highway 5, to a depth of four feet.
Additional soils would be excavated down to the water table, depending on PFC soil concentrations found. 3M proposes to take excavated soils to the SKB Landfill, a permitted industrial landfill in Rosemount, where they will be placed in a secure long-term containment cell.
The site would then be backfilled with clean fill and maintained long-term by 3M. Groundwater monitoring will continue for at least 30 years to ensure the site is not a source of PFCs in groundwater.
The proposal is open for public comment through June 20. Comments must be submitted in writing to Gary Krueger, MPCA, Remediation Division, 520 Lafayette Road N., St. Paul, MN 55155-4194.
After the comment period closes, the agency will finalize the remedy selection with any applicable modifications. The MPCA commissioner will make a decision on the remedy, which will be outlined in a final decision document.
Copies of the feasibility study and other documents relating to the site and the proposed cleanup are available for review on the Web at www.pca.state.mn.us/cleanup/pfc/pfcsites.html, as well as at the MPCA's St. Paul office.