A large scrap metal recycler on the city's upper riverfront is claiming that a state regulator is singling it out over dust emissions and asserting that it has taken every step available to control such particles from its riverside yard.

Writing for Northern Metal Recycling, Michael Hansel, an engineer at Barr Engineering, asserted in a letter to the agency that for several half of the exceedances of a total particles standard the firm couldn't have been responsible for them. A state monitor is located across the street from the firm.

The standard was exceeded for the fifth time in six months on March 19, according to that monitor. The Minnesota Pollution Control Agency posted that on a web site for the monitor but didn't alert the public via e-mail until Friday.

Hensel said Friday that after a company Data Practices Act request, it appears that only other one of the six companies within one-quarter mile of the monitor responded with data when asked by the agency about their activities. That was GAF, a shingle company.

The engineer wrote that agency officials have told him that they intend to take the issue of the exceeded standards "to the next level." He said in an interview that could take the form of a letter asking for changes at the firm, a warning letter or a notice of a violation.

Hensel asserted to the agency that the wind direction and lack of barge loading operations suggest that the scrap yard didn't contribute to or was a minor factor in all but one of the episodes. He said that unless the agency can show that the firm contributed to the emissions, further controls shouldn't be investigated.

"My client already has every conceivable control measure installed and operating, and is the most tightly controlled and regulated metal shredder in the United States," Hensel said. The firm has three types of dust control installed in its shredder building. It also sprays the yard and sweeps it, except in freezing temperatures.

The firm began operating a shredder several years ago to increase the market value of its scrap metal at mills. That followed a long-running controversy in which some area residents sought to block a shredder at a yard where scrap has been processed since 1951.

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.

Jeff Smith, director of the agency's industrial division, said that because the investigation of the exceedances is continuing, he's limited in what he could say. He said that Hensel's assertions about the agency not following protocols and location of monitors are based on misunderstandings. He characterized Northern Metal as reluctant to participate in the agency's investigation and said he hopes for more cooperation.

(Photo: Scrap metal enters the shredder operated by Northern Metal Recycling. Staff photo by David Brewster.)