Cleanup, Monitoring Ongoing at Cohasset Coal Plant After Wastewater Spill

The Boswell Energy Center, a coal power plant in Cohasset. (Credit: Minnesota Power)

The Minnesota Pollution Control Agency has released an update on the wastewater spill from Minnesota Power’s Boswell Energy Center near Blackwater Lake in Cohasset.

Last Friday, Minnesota Power increased its estimate of released coal ash wastewater from one million gallons to 5.5 million gallons. An update today says vegetation near the wastewater spill near Blackwater Lake in Cohasset did not show any signs of stress, and initial samples show increased levels of sulfates within the creek near the lake.

Excavation of the source area and impacted soil is ongoing. Estimates show the crew at the site has removed approximately 18,000 gallons thus far.

The primary contaminants of concern are sulfates, chlorides, and boron. In the field, responders have been using conductivity and a sulfate field meter to indicate where the released materials are, and to monitor where they may potentially migrate.

Results are fluctuating daily and are up to four days behind due to lab turnaround times. The ongoing sampling and monitoring will help determine how widespread or severe the impacts are, and what tools and technology will be most effective to minimize impacts.

Minnesota Power reported the incident at the Boswell Energy Center on July 16th. The report said a spill of ash wastewater was discovered, but that the spill was no longer active. According to the report, the spill did not affect sewers.