Minnesota power plant leak: 1 million gallons of coal-ash wastewater spill from Cohasset facility

A significant environmental incident has occurred at Minnesota Power’s Boswell Energy Center in Cohasset, Minnesota. A break in an underground plastic pipe has released one million gallons of coal ash-tainted water, raising concerns about local water sources and wildlife. This incident has prompted swift action from the utility company and environmental authorities.

Immediate response and containment measures

Minnesota Power discovered the leak after noticing standing water near the break site, indicating a pipeline failure. The company quickly contained the spill using earthen berms and booms. The leak, located at a bend in the underground pipe before it crosses Blackwater Lake, caused water to flow overland and potentially into the lake.

The Minnesota Pollution Control Agency (MPCA) and the Environmental Protection Agency (EPA) were promptly notified. Andrea Cournoyer, an MPCA spokeswoman, confirmed the agency’s involvement in the ongoing investigation.

The spill was detected at 11:15 a.m. on Tuesday, with a report filed just 15 minutes later. Minnesota Power initially linked the incident to a “loss of pump pressure,” later clarifying this was a signal rather than the cause of the leak.

Environmental implications and cleanup efforts

Coal ash, a by-product of coal combustion, contains pollutants like mercury, cadmium, and arsenic, which can contaminate water and air if not properly managed.

The pond from which the water was siphoned was used between 1980 and 2015 for fly ash disposal. It has since been decommissioned, and the water is now used for various processes at the Boswell plant, including dust suppression.

Minnesota Power aims to dewater the pond by the end of coal operations at Boswell, scheduled for the mid-2030s.

The plastic pipe responsible for transporting the water was installed around 2014 or 2015. Company representatives are still determining how long the pipe had been leaking.

The MPCA, EPA, and Minnesota Power are collaborating to mitigate the environmental impact of the spill.

The water involved in the spill was not treated between the pond and the plant, meaning it could carry residual pollutants. Efforts are being made to recapture some of the spilled water and return it to the pond.

Local impact and ongoing monitoring

Blackwater Lake, a 674-acre reservoir on the Mississippi River, is the primary body of water potentially affected by the spill.

The lake’s levels are controlled by the Pokegama Dam, operated by the U.S. Army Corps of Engineers.

The Minnesota Department of Natural Resources (DNR) describes the lake as “essentially a flooded river channel” and notes that the area where heated water from the plant is discharged is popular with anglers.

Local authorities are closely monitoring the situation. Cohasset’s public works and utility supervisor, Walter Shadley, confirmed that the town does not draw its drinking water from the Mississippi River.

Steve Robertson, assistant manager of the Minnesota Department of Health’s Drinking Water Protection section, stated that early information suggests a low risk to local drinking water supplies.

Any potential effects on the aquifer could take up to a year to manifest, and further assessments will be made as more information becomes available.

The Boswell Energy Center is Minnesota Power’s largest electricity source, with its two coal-fired units capable of producing 932 megawatts of electricity.

As part of its transition to carbon-free power, one unit is scheduled to retire in 2030, with the second set to close in 2035.

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