Polymet will repurpose much of the former LTV mine operation building.

An environmental group is asking regulatory agencies to reopen parts of the environmental review for the proposed PolyMet copper-nickel mine near Hoyt Lakes.

WaterLegacy is claiming that changes to the mine’s tailings basin and wastewater facility, and a disclosure on how much water will pump into the mine, warrant another look. Reopening the review could add more time to the review process, already more than a decade along.

In a letter Thursday that included the U.S. Corps of Engineers and the Minnesota Department of Natural Resources, the group’s lawyer claims the company changed plans after the final environmental impact statement was approved in March 2016, and before it began submitting permit applications, calling it a “bait and switch.”

"The project keeps changing and these are not changes for the better," said Paula Maccabee, an attorney for WaterLegacy, told The Associated Press.

PolyMet countered saying the changes don’t significantly change the environmental review.

"Project refinements are a normal part of the permitting process and are designed to make the project even better," said PolyMet spokesman Bruce Richardson.

Maccabee cited three major changes to the AP that she said merit a supplemental environmental review:

• The design of the tailings basin dam. PolyMet had proposed to use a technique called "cement deep soil mixing" to stabilize the soil in the basin area and reduce the risk of a dam failure. The method involves drilling deep holes and filling them with cement to form columns that provided added strength and stability. The new plan, laid out in the permit applications, would use additional buttressing instead.

• The original plan included a water treatment facility at the mine site near Babbitt to reduce sulfates, metals and other pollutants before the wastewater gets pumped to the processing plant 9 miles away near Hoyt Lakes. The new plan is for pipelines to carry untreated water from the mine to the plant for treatment.

• The amount of water pumped from the mine site to the processing plant could hit 3.7 billion gallons annually. The final environmental impact statement didn't put a figure on how much water could be involved. Maccabee said that means none of the previous analyses on the effects on streams and wetlands adequately account for that much pumping.

Richardson further said the changes don’t merit reopening the review, and added that PolyMet has undergone the state’s toughest test and met the standards.

The Associated Press contributed to this report.


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