3M Co. paid $80,000 for numerous alleged hazardous waste violations at its Cottage Grove plant and incinerator, according to an enforcement action the Minnesota Pollution Control Agency (MPCA) announced Wednesday.

At issue was a release of "extremely toxic" hydrofluoric acid, a regulated hazardous waste, from corroded barrels in 2019, and many alleged violations regarding how 3M was handling and storing hazardous waste at its Cottage Grove complex.

Hydrogen fluoride is a particularly risky chemical. It has long been used at oil refineries, and the tanks of it were a major concern during the explosion at the Husky Energy oil refinery in Superior, Wis., in 2018.

Seven companies have the chemical on site in Minnesota, state records show, with the largest amount at the St. Paul Park refinery now owned by Marathon Petroleum, followed by 3M's Cottage Grove plant.

3M paid the $80,000 civil penalty and finished 15 corrective measures, the MPCA said.

Sean Lynch, a spokesman for the Maplewood-based manufacturer, provided a statement saying 3M is serious about environmental and regulatory compliance.

"Through the actions outlined in the Stipulation Agreement, we will help ensure consistent compliance in this facility's use of regulated materials, provide a safe working environment for our employees, and reaffirm our role as a positive presence in the Cottage Grove community," the statement said.

Lynch could not immediately confirm how 3M uses hydrofluoric acid.

The enforcement action ends a two-year investigation the MPCA began in 2018 after an inspection of 3M's Cottage Grove complex revealed spills and storage issues, the regulator said. The facility generates more than 2 million pounds of hazardous waste a year.

The state dinged 3M for 15 alleged violations of the facility's air and hazardous waste permits.

They include 3M waiting two days in 2019 to notify state regulators when 3M workers found hydrofluoric acid gas leaking from four corroded 55-gallon hazardous waste containers, and not activating its emergency plan when it happened. Several more of the drums had "bulging tops."

3M reported those drums held at least 90% "fluorochemicals" and only 10% or less hydrofluoric acid, according to the agreement. Fluorochemicals typically refer to the per- and polyfluoroalkyl substances called PFAS that are resistant to breaking down.

Although 3M manufactures a newer type of the "forever chemicals" at the plant, and burns PFAS contaminated waste in the incinerator, those man-made chemicals are not regulated as a hazardous waste yet, and were not the concern in Wednesday's enforcement action.

Other problems the MPCA cited included storing hazardous waste in the wrong places, storing containers for more than the one year allowed and stacking them in ways that obstructed access to them.

The alleged violations also involved 3M employees not rapidly cleaning up spills and leaks, such as the wastewater MPCA inspectors noted was leaking from a truck hauling saturated ash from the incinerator to a containment building.

The regulator has taken other enforcement actions against 3M for hazardous waste violations at Cottage Grove over the decades, state records show. Among the largest was a 1989 enforcement agreement with a $1.5 million fine.

The MPCA has developed a new blueprint for tackling the ever-widening scope of PFAS pollution in the state.

The plan identifies a long-term need to regulate PFAS as a hazardous waste. Shorter term, it calls for clearly designating the entire class of PFAS as a "hazardous substance" in state law. Among other things, that designation would require companies to disclose the PFAS they use to regulators. That effort fizzled earlier in the legislative session.

Jennifer Bjorhus • 612-673-4683