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Environmental group says changes in PolyMet mining plan are significant

The environmental group WaterLegacy has asked federal and state agencies to conduct another environmental review of the proposed PolyMet copper mine after the company submitted revised plans for wastewater treatment and dam safety.

The changes surfaced in applications for state permits that PolyMet is now seeking to start construction on the open-pit mine and processing center north of Hoyt Lakes, what would be Minnesota's first copper mine.

Minnesota-based WaterLegacy has asked the U.S. Army Corps of Engineers and other federal and state agencies to require a "supplemental environmental impact statement" and hold additional public hearings on the changes.

State and federal regulators essentially signed off on the environmental impact statement for the project early in 2016. But while the environmental impact statement looked at broad impacts of proposed mining actions, the permit applications are far more detailed. They explain exactly how PolyMet plans to build and operate the mine.

Paula Maccabee, attorney for WaterLegacy, says the changes appearing in permit applications are intended to cut costs for PolyMet but could increase the chances for environmental problems down the line.

PolyMet officials say that won't happen, and that the changes won't shortchange safety or environmental protection and don't rise to the level of requiring another environmental review.

"Project refinements are an accepted and normal part of the permitting process. They are intended to make the project even better. In our case, we have made modifications to our tailings dam design and eliminated one water treatment facility," said Bruce Richardson, PolyMet spokesman. .

PolyMet had proposed pumping cement underground to help shore up the dam that holds back a man-made lake filled with leftover mining waste, called a tailings basin. The company now wants to skip the cement and instead use exterior rock to help stabilize the dam, part of the old LTV Steel Mining Co. tailings basin that PolyMet wants to reuse.

"Under at least one scenario, according to PolyMet's own analysis, the new proposal would reduce tailings dam stability below the safety margin," Maccabee said.

But Richardson said the revised tailings dam design "maintains a similar level of safety as the previous design."

PolyMet also proposes to eliminate a proposed water treatment facility at the mine site, which Maccabee said had been "a centerpiece of the project" in the environmental impact statement.

"In order to reduce its own up-front capital costs, PolyMet has proposed to do away with technology to reduce the risk of catastrophic tailings dam failure and eliminate the mine site wastewater treatment facility that was a central part of its plan to prevent long-term toxic pollution," Maccabee said in a statement.

Richardson said the mine site water will still be treated, and that the company can combine treatment at one site and still "maintain the same quantity and quality of water under a single water treatment plant."

PolyMet's permit applications also have detailed that the operations will use up to 3.7 billion gallons of water annually. Maccabee said that amount of water use from the Partridge River watershed will have a much broader impact on wetlands in the area than previously stated.

State and federal regulatory agencies are expected to start rolling out proposed permits in coming months for public review and hearings. PolyMet hopes to begin receiving permits next year to start construction and operation of the mine and processing center.

Several lawsuits have been filed in federal court saying the environmental review gave short shrift to endangered species, and alleging that federal land at the mine site is being undervalued in a land swap with the company.