A long-running environmental battle in Minneapolis took a new twist Thursday when a state regulator announced legal and administrative action to halt operation of a north Minneapolis metal shredder that it blames for repeated violations of air-quality standards.

The Minnesota Pollution Control Agency (MPCA) alleged that shredder operator Northern Metal Recycling wasn't truthful about emissions from the shredder when it was issued a state permit, has changed operations since the permit was issued without telling the agency, or both.

The action was applauded from City Hall to upper riverfront neighborhoods, where the shredder has been viewed by activists as an obstacle to greener redevelopment.

"This is an environmental justice issue that impacts one of our most overburdened neighborhoods," Mayor Betsy Hodges said in a statement. "We must not let the health of our residents, including our children, be determined by their ZIP code."

But Northern Metals disagreed with the MPCA's action and findings.

"Northern Metals is an environmentally responsible company and has consistently invested in the best available technology on the site," the company said in a statement. "We strongly contend that we have acted transparently and are in compliance with the current permit in full. To this end we will be submitting our response to the district court and are confident that the facts will support our position."

The rare move to revoke a permit, if successful, would mean that the company would need to apply for a new permit to shred metal there. The shredder began operating in 2009 to increase the price of scrap by producing smaller, cleaner chunks of metal for downstream mills.

Longtime controversy

The MPCA filed Wednesday for a temporary injunction in Ramsey County District Court to stop operations of the Northern Metal Recycling shredder at 2800 N. Pacific St. and further processing in two nearby buildings. A June 9 hearing is scheduled.

The state agency said the shredder isn't airtight as the firm represented, allowing potentially harmful dust to escape. It also alleges that further processing of shredded material in two nearby buildings exposes the public to health risks.

Residents of nearby neighborhoods applauded the move.

"I'm hopeful that this is the beginning of things changing on the upper river for one of the many polluters we have," said Anna Bierbrauer, a Bottineau neighborhood activist.

David Luce, a Hawthorne neighborhood resident, said, "I'm happy that the agency is making a move on them."

The MPCA also has moved administratively to revoke the firm's air-quality permit. That process could take months if the company exercises its right to contest the move through a hearing process.

The start-up of the shredder followed a 20-year battle over permitting that played out in City Hall, the courts and the Minnesota Legislature. Opponents feared dust containing heavy metals would waft over the river and into nearby neighborhoods; the company said it was installing the best available pollution controls in its shredder.

The shredder is contained within a building in which pollution controls are supposed to capture dust, but the MPCA said the building leaks. It said that in nearby operations, the firm is trying to extract more metal from the material captured by those controls, but is doing so in conditions that don't meet permit requirements.

The agency upped the limits for pollutants from the machine in 2012 when it failed to meet initial air quality standards. The MPCA also installed air monitors bracketing the yard that recorded readings above standards. The company disputed that it was the source.

The MPCA's action comes as the company seeks $20 million in the Legislature to help it move the shredder, but not the scrapyard, to a new facility with railroad access that it wants to develop northwest of the Twin Cities area.