It's finally decision time for the north riverfront metal shredder operated by Northern Metals.

The Minnesota Pollution Control Agency staff is recommending that a permit amendment for the controversial shredder be granted without further environmental studies. That recommendation will be considered by the agency's board at a special meeting on Oct. 1 at agency headquarters in St. Paul.

If the board ratifies that recommendation, the matter next progresses to a second board meeting on
Oct. 23, for a vote on the actual permit amendment. But a request for a contested case hearing, which would slow the process by several months, also is pending before the board at that meeting.

The proposed permit amendment makes several changes. One is to set a new limit on minute particles that can be emitted, which can have an impact on human health. The current limit is based on filterable particles collected before air goes out a stack. But a proposed new level based on evolving science takes into account particles that form after the stack when gases condense into solids. Although the limit is higher in terms of pounds per hour, that's because it's taking into account the second source of particles, according to Jeff Smith, director of the agency's industrial division.

The agency also proposed tightening its proposed limit on particles because of changes in the background amount of such particles measured at monitoring sites since it first proposed an amended permit almost a year ago. Had the company not agreed to the change, the agency likely would have required further study of the environmental impact, Smith said.

The proposed permit also would allow the company to shred whole auto hulks after they've been stripped of contaminants. The shredder now is limited to processing pieces of hulks, a limit not placed on some other shredders in the state.. The permit also changes the three pound per year limit on mercury emissions from a daily calculation to a 12-month rolling average.

Northern has been seeking an amended permit ever since shortly after the controversial shredder, installed after lengthy regulatory and legal delays, failed to meet limits in its original state permit. It began operating in 2009.