When black smoke settled over the Northern Metals facility in Becker, Minnesota, the smog hovered for almost a week. Nearby, Great River Energy’s Liberty Substation was so covered in smog that employees couldn’t perform a visual inspection of the substation equipment due to health concerns.
Most of the substation had to be de-energized as a safety precaution to avoid a potential flashover—which can cause a fire—as soot hung in the air.
When the fire stopped burning, employees had to figure out how to clean the ashes and soot off the substation’s transformer and breaker bushings, line insulators and other critical equipment.
“Our substations and equipment are designed to withstand naturally occurring elements like dust, ice and snow,” said Marty Koepke, leader of substation apparatus at Great River Energy. “But this wasn’t regular dust—it stuck to our equipment. This was unusual because the equipment is designed such that rainwater and wind will naturally clean the dust off. But that changes when you get this type of unusual contaminants. We had to find other ways clean the substation.”
The group worked with crews from Open Air of St. Cloud, Minnesota, which performs dry ice cleaning.
“We also had metering, relaying and substation apparatus crews cleaning,” Koepke said. “These crews did an exceptional job. Open Air had said it could take up to three days, but with our crews assisting, we were able to clean the equipment in a day and a half.”
Great River Energy will be reimbursed by Northern Metal’s parent company, EMR, for the cost of cleaning the equipment.