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State questions PolyMet on lack of underground mining option in study

The Minnesota Department of Natural Resources has asked a private contractor to provide more information on why underground mining isn't a viable option for the proposed PolyMet copper mine near Hoyt Lakes.

The contractor compiling the Environmental Impact Statement for the mine had concluded, in a preliminary draft of the EIS, that an underground mine wasn't "economically viable'' compared to the company's planned open-pit mine.

The dismissal of underground mining as an option was discovered in a preliminary Draft Environmental Impact Statement, dated June 2008, obtained from the DNR through open records requests by the Minnesota Center for Environmental Advocacy.

Under "Alternatives Considered But Eliminated,'' the June version of the EIS lists underground mining as meeting the purpose and need of the company, technically feasible, available and possibly offering significant environmental benefits. Still, underground mining wasn't considered for environmental review because of the expected cost to the company.

Stuart Arkley, DNR project manager for the PolyMet environmental review, said he returned the chapter to the contractor.

"You can't just say it's not economic,'' Arkley said. "We want them to show their work. ... It may well be that underground mining is technically not feasible, but we need to know why.''

Arkley said several entire chapters were not finished in time for the June draft report and that the documents released should not be considered the DNR's final version. But he also cautioned that underground mining may be impractical for the site, noting the vein of copper in that location is very close to the surface.

PolyMet officials always have proposed an open-pit mine because the copper is so close to the surface.

"At one point it's just 10 feet below the surface,'' said LaTisha Gietzen, PolyMet vice president of public affairs. "The deepest we go is about 800 feet."

At other proposed mine locations in the region, copper deposits are much deeper, up to 3,500 feet below the surface, and underground mines are considered the only viable access.

Environmental groups have questioned PolyMet's ability to prevent sulfuric acid runoff from the mine and piles of waste rock and say the preliminary EIS already cast doubts on the credibility of the state's environmental review.

Mary Marrow, attorney for MCEA, said the EIS contractor's decision to ignore a viable mining method without reviewing all options violates state environmental law.

"We don't know if an underground mine would be better to protect Minnesota's environment. ... But excluding an option solely for economic reasons is clearly a violation'' of both the Minnesota Environmental Protection Act and the Minnesota Environmental Rights Act, she said.

PolyMet is proposing Minnesota's first copper mine that also would produce nickel, platinum and other valuable metals. The mine site is near Babbitt, while the company plans to use the former LTV Steel taconite plant near Hoyt Lakes as a processing center. The company says it will create 400 or more jobs for more than 20 years during mining operations.

Critics say that copper mining has a poor track record in other regions. Because copper is locked in rock that often is high in sulfur, mining operations can release high levels of sulfuric acid when rock and waste rock is exposed to air and water.

That sulfuric acid runoff can damage streams, lakes and wetlands. (Taconite, by comparison, usually is in rock with little or no sulfur.)

PolyMet officials say rock at the mine sit is very low in sulfur compared to other copper mines and that they will take extreme care to collect any runoff from the mine and waste rock storage areas, preventing any water pollution.

Marrow said keeping most of the waste rock underground, and keeping exposure to air and water to a minimum, might be a better economic alternative than exposing millions of tons of rock through an open pit mine. She said the DNR has offered no data to show that underground mining is not economically feasible.

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