A judge has ordered the Minnesota Pollution Control Agency to shut down two air monitors that bracket property owned by the Northern Metal scrap yard in north Minneapolis or explain by July 27 why not.

Ramsey County District Judge John Guthmann issued his order last Thursday in an action brought by Northern Metals, which alleges that it is unfairly being singled out by the agency as it investigates five instances in which an area monitor recorded air particles over the allowable standard.

The agency said Monday in a statement that it "has no intention of shutting the monitors down and intends to prove to the court that it has the authority and responsibility to monitor air quality, and we believe that Northern Metals' argument has no legal merit."

Assistant Commissioner David Thornton went further. "I know that we think they're out to lunch on this," he told a reporter.  "They're just wrong."

Company President Stephen Ettinger wrote, "Unfortunately I felt the need to petition the court to compel the MPCA to follow their own rules, for the second time in the past four years or so." But area state Rep. Joe Mullery criticized the company: "Amazingly, they are trying to prevent an agency which exists to protect the public from pollution from actually doing its job."

Northern Metal owns the former American Iron yard on the west bank of the Mississippi River, just south of the Lowry Avenue Bridge. The company and some area residents have been battling for about 20 years over installation and operation of a metal shredder that pulverizes scrap. The machine operates inside a building and the company uses several techniques to capture particles generated by the machine.

The agency's prior modeling for its air permit estimated that shredder would release 3.5 tons annually of particles, but the firm said that represented a miniscule amount of particles in the industrialized area.

The firm's court filings allege that the agency didn't follow state and federal procedures regarding the location of its monitoring stations. It said the agency continued the operation of an air monitor across the street from the scrap yard beyond its planned removal, and added a second such monitor on city property on the opposite site of the yard, without going through the proper public process.  It also said the agency switched the size of particles it was monitoring at one of the sites without following proper procedures.

The firm said the agency was operating the monitors with the apparent purpose of blaming Northern Metals without scientific support for that. It said that company's Data Practices Act requests found no evidence that the agency was investigating any other possible area source of the particles.  The company said its analysis suggested that wind speed and direction data for the days of the standard violations make it likely that other sources produced the measured particles.

The agency has said little publicly about its investigation into the particle violations, saying state law precludes it from doing so until its investigation was completed. It didn't disclose the addition of the second monitor until Monday, 11 days after the firm said it was informed.

The agency in 2012 modified the company's emissions permit, which a test conducted soon after the shredder began operating in 2009 showed that the company was violating. The state rejected the need for further environmental studies sought by area lawmakers after concluding that the shredder would increase the area’s concentration of more dangerous small particles by 2 percent.  It installed the monitor shortly after but the violations haven’t involved the small-particle standard but rather those for overall particles.