Public Comment Form

Commenting open: July 01, 2024 12:00AM CT - August 15, 2024 11:59PM CT.

3M Chemical Operations (Cottage Grove) - Wastewater Permit

We invite you to comment on the draft wastewater permit for 3M Chemical Operations in Cottage Grove.

3M’s facility in Cottage Grove manufactures a diverse group of products including abrasives, organic chemicals, polymers, resins, ceramic solutions, fluorochemicals, tapes, films, coatings, and extrusions. Chemical production includes a variety of per- and polyfluoroalkyl substances (PFAS). The facility treats its own sanitary wastewater and stormwater as well as non-contact cooling water, wastewater that it creates from its production processes and pilot production lines, contaminated groundwater, leachate from SKB Environmental’s Rosemount landfill, water from LSP’s Cottage Grove power station, and water from activities related to decommissioning the site’s incinerator.

The facility discharges treated wastewater to an unnamed creek that flows into the Mississippi River. Under the draft permit, the facility would be allowed to discharge up to 15.2 million gallons of treated wastewater per day.

The draft water quality permit protects water quality for aquatic life, recreation, and human fish consumption by limiting pollutant discharge as required by federal regulations and applicable water quality standards. It sets new or lower discharge limits for:
· six PFAS compounds
· seven heavy metals
· 55 semi-volatile or volatile organics
· aggregate toxicity to aquatic organisms
· ammonia
· phosphorus

The draft water quality permit also requires PFAS monitoring:
·  in all treated wastewater
·  at 19 stormwater discharge locations
·  in seven internal waste streams
·  at upstream and downstream surface waters
·  in the tissue of fish caught in the Mississippi River near the facility and downstream of it

The draft permit also includes new routine monitoring for semi-volatile and volatile organics, metals, and salts.

The MPCA proposes to modify the maximum load of total suspended solids from the facility in the South Metro Mississippi River total suspended solids study. The maximum load of total suspended solids in the study, approved by the EPA in 2016, was 545 kilograms per day at a single monitoring station. The addition of a second monitoring station will bring that maximum load to 1,532 kilograms per day. The modification will not contribute to the total suspended solids impairment in the South Metro Mississippi River.

Wastewater from industrial and commercial sources may contain pollutants at levels that could adversely affect the water quality in area wetlands, streams, rivers, and lakes. Water quality permits - or National Pollutant Discharge Elimination System (NPDES) permits - establish specific limits and requirements to protect Minnesota's surface and groundwater quality. All wastewater must be treated before it goes into surface water to protect human health and aquatic life. Permits are regularly reviewed and updated as they expire, allowing the MPCA to incorporate new information about the impacts of pollutants on the environment in future permits.

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Your Comment

Thank you for providing feedback on this project. We value your comments and will use them to assess this project further. Please submit your comments and feedback before the end of the comment period. If you want to submit a letter, you can upload the letter on this website or submit it via US Mail to the following address: Minnesota Pollution Control Agency

c/o Emily Schnick
520 Lafayette Rd N
Saint Paul, MN 55155

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