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Eagle Mine air quality

Permit requests, public comment subject of virtual meeting

Permit requests for the Eagle Mine and Humboldt Mill were the subject of a virtual public meeting held by the Michigan Department of Environment and Great Lakes on Monday. (Journal file photo)

MARQUETTE — Permit requests for the Eagle Mine and Humboldt Mill were the subject of a virtual public meeting held by the Michigan Department of Environment and Great Lakes on Monday.

Eagle Mine officials have proposed adding an on-site aggregate and sand storage area immediately north of the mine’s existing temporary development rock area in Michigamme Township, where it will operate a development rock screening plant.

Company officials are also asking to revise the permitted allowable trucking limits from a 12-month rolling limit to a calendar-year limit for both the Humboldt Mill and the Eagle Mine to cover periods of adverse weather conditions.

Development rock is non-ore-bearing rock material of varying sizes that is trucked out of the mine and stored at the TDRA.

According to the June 19 permit, the request, if approved, will “optimize the reliability” of the mine’s backfilling operation by allowing it to store a larger quantity of aggregate and sand, which is used to make cement to backfill areas of the mine where mining activity has ceased.

“Due to the size of the existing aggregate storage building, adverse weather conditions and other logistical issues can limit Eagle’s ability to maintain a consistently adequate quantity of appropriately-sized aggregate on site, which can adversely impact backfilling operations,” the permit request states.

EGLE Air Quality Division Project Manager Andy Drury said both the mine and the mill are currently operating “as allowed” under previously issued permits.

“The Eagle Mine wants this additional storage so they can bring aggregate and sand to the facility while travel conditions are good,” Drury said, “and avoid bringing material to the area when travel conditions are bad, especially in the winter. To better optimize mine backfilling and off-site transportation operations.”

EGLE’s draft permit requirements for the outdoor aggregate and sand storage will restrict the company to a 5-acre size limit, a 5% opacity limit, and will require a fugitive dust plan, Drury said.

Changing the timeframe of the trucking permit does not change the projected vehicle emissions.

Upper Peninsula Environmental Coalition representative Kathleen Heidtman said the group is concerned that emissions caused by the proposed sorting process and the increased amount of exposed aggregate would be difficult to assess.

“I would say that our primary concerns have to do with the emissions that are expected from the screening area. That unit … represents a new and difficult to assess emissions. We request a greater amount of testing because of that … There is a huge quantity of rock out there right now. There is no cover to it and even though emissions could be reduced by misting in that area,” Heidtman said. “I don’t think that it’s in the mine’s best interest to mist there because that (water) will have to be additionally treated before collecting.”

Comments about the proposed permits can be emailed to EGLE at EGLE-AQD-PTIPubliccomments@michigan.gov until midnight on Friday.

The current air quality permit for Eagle Mine was issued on June 28, 2013. The Humboldt Mill’s initial permit was issued on Jan. 27, 2014. The mill and mine are currently operating as allowed by this permit, officials say.

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