REGIONAL—Is PolyMet walking back promises it made to maintain high environmental and safety standards at its proposed NorthMet mine, near Hoyt Lakes?

That’s the contention of attorney Paula Maccabee, with Duluth-based WaterLegacy, who is asking the Army Corps of Engineers to require a new supplemental environmental impact statement for the mine due to what she sees as significant changes to the mine plan since the state’s Department of Natural Resources signed off on the environmental impact statement last year.

Maccabee said most Minnesotans view the environmental mitigations that a company proposes during the EIS process as actual commitments. But she said the project now being proposed by PolyMet as part of the permitting process is different in some important ways, and not for the better. “It’s really a case of bait and switch,” she said. “In order to reduce its own upfront 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 at the mine site.”

In a detailed submission to the Army Corps citing PolyMet’s own permitting applications and technical documents, Maccabee argues that federal regulations require a supplemental EIS and public hearings on PolyMet’s new proposals. “Information in the Minnesota state permitting process demonstrates that there are significant new circumstances and new information relevant to environmental concerns and bearing on the proposed action and its impact that requires a supplemental EIS be prepared,” stated Maccabee in her letter.

PolyMet officials have dismissed WaterLegacy's actions in a statement to supporters. "The group has attacked the project in every way it can and likely will continue to do so," said company spokesperson Bruce Richardson. "WaterLegacy’s latest attack cites design changes to our tailings basin, our combining of two water treatment plants under one roof, and its own erroneous calculations for our water allocation plans as reasons for regulators to “conduct a fresh environmental review of the revisions.”

Richardson said revisions are typical on a large project. "Project refinements are an accepted, normal and ongoing part of the permitting process. They are intended to make the project even better."

Meanwhile, officials with the Department of Natural Resources say they’re still evaluating WaterLegacy’s request. “At this point, we have not identified any proposed changes that would require a supplemental EIS,” said DNR Assistant Commissioner Barb Naramore. “We defer to our federal co-lead agencies, the U.S. Army Corps of Engineers and U.S. Forest Service, in evaluating this question in the context of federal environmental review standards.”

Changes in mine plan

Maccabee contends that key changes in the mine plan, at both the mine site and at the company’s processing plant and tailings basin, located about nine miles away, render the current EIS inadequate. At the mine site, the company is proposing to eliminate the construction of a wastewater treatment facility that was supposed to pre-treat contaminated water before pumping it to the tailings basin. It was also expected to be used to treat water at the mine site following closure, potentially for hundreds of years.

Naramore contends that the change is less than meets the eye. “There would still be wastewater treatment under the company’s proposed design modification,” she said. “In essence, what they are proposing is to consolidate wastewater treatment capacity for both the mine site and the plant site in one location, at the plant site.”

Maccabee says the change is about more than water quality. Under the proposed change, she said, PolyMet would pump an estimated 3.7 billion gallons of water discharged annually from the mine site to the tailings basin, which is likely to slow or halt wetlands recovery at the mine site post-closure.

WaterLegacy is also concerned that adding that much additional water to the tailings basin increases the risk of what’s known as “liquefaction,” which can make tailings dams unstable and subject to catastrophic collapse, such as occurred at the Mount Polley mine site in British Columbia in 2014. Adding to the concern is the fact that PolyMet now wants to eliminate its proposal to undertake what is known as “cement deep soil mixing” along portions of the tailings basin wall. “The FEIS proposed that cement deep soil mixing would be used to reduce slope instability and reduce the risk of dam failure,” noted Maccabee in her Army Corps letter.

The company now proposes using additional buttressing instead, which could be installed in stages as mining proceeds, rather than upfront as would be the case with cement deep soil mixing. Maccabee said she’s not sure which of the two methods is superior, but she notes that the decision to make the switch is clearly being made to reduce upfront costs for PolyMet, rather than to improve environmental safety.

In either case, she said, it represents another major change that should be analyzed by a supplemental review.

“They have characterized their project as providing excellent technology and financial assurance,” said Maccabee. “It seems clear they are scaling back on those promises.”

Richardson denied that suggestion. "Our revised tailings dam design is to the same safety standards as the previous design, but it allows for more effective monitoring and is easier to implement," he said.

"And we will treat the same quantity of water to the same standards using the same treatment technology as we would with two treatment plants – and reduce wetland disturbance in the process due to a smaller footprint."

Drafting a supplemental EIS would likely not require an entirely new environmental review process, since the Army Corps, unlike the DNR, has yet to make its own determination on the adequacy of the EIS submitted by PolyMet last year. That determination would typically come with the issuance of the Section 404 wetlands and water quality permit. PolyMet submitted its application for that permit to the Army Corps in 2013.