ST. PAUL — The latest environmental review for the proposed PolyMet copper-nickel mine shows “extensive improvements” over the original but still needs work, the Environmental Protection Agency said Thursday.

The federal agency rated the original 2009 document as “environmentally unsatisfactory — inadequate,” or “EU-3,” the lowest possible grade. On Thursday the EPA gave the update released in December a substantially better rating of “environmental concerns — insufficient information,” or “EC-2.” That’s just one notch below the best rating it realistically had a chance of getting, according to state and company officials.

“This rating demonstrates the significant improvements PolyMet has made to the project in response to previous public and regulatory comments,” PolyMet’s president and CEO, Jon Cherry, said in a statement.

Thursday marked the deadline for public comments on the nearly 2,200-page document, formally known as a supplemental draft environmental impact statement, or SDEIS. The Minnesota Department of Natural Resources will consider the EPA’s recommendations and comments from the public as it prepares the final version.

Leaders of several environmental groups denounced the review as incomplete despite its length, telling reporters that it fails to address crucial questions about how the mine near Babbitt and processing plant near Hoyt Lakes would affect the environment in northeastern Minnesota.

PolyMet’s proposed NorthMet mine would be the state’s first copper-nickel mine, if it clears all the legal hurdles. It’s expected to set the pattern for environmental protection for future mining proposals in the region, which holds vast untapped reserves of copper, nickel and precious metals.

“We appreciate the extensive improvements to the project and the clarity and completeness of the environmental review that are reflected in the SDEIS,” wrote Alan Walts, director of the EPA’s Office of Enforcement and Compliance Assurance in Chicago.

But the EPA recommended improvements in 37 specific areas. It wants a clear explanation of how long water from the mine and plant sites will require treatment. PolyMet’s critics interpret the SDEIS and supporting data to say the plant site will need 500 years or more of treatment while the mine will need at least 200 years of it — a reading that the DNR and PolyMet dispute. The EPA also said the final document should include more information on financial assurances the company will be required to provide to ensure that taxpayers aren’t stuck with cleanup bills.

 

Cherry said PolyMet will work with regulators to get them the additional information needed to address the EPA’s concerns.

 

 

 

The DNR was hoping for the EC-2 rating, agency spokesman Chris Niskanen said, calling it a passing grade.

“This rating means the EPA thinks there are still some potential project modifications that are needed to reduce impacts on the environment, but the rating also means that the EPA is not finding any serious deficiencies in the SDEIS, and that the proposed project does not need any substantial changes,” Niskanen said.

PolyMet has spent $40 million on additional studies, a pilot plant for testing water treatment technology and other work since the original review, company spokesman Bruce Richardson said.

Several environmental groups filed detailed analyses just ahead of the deadline, urging the DNR to send the review back to the drawing board. The document contains no discussion of human health impacts or what happens when things go wrong such as treatment plants breaking down or dams leaking, said Scott Strand, executive director of the Minnesota Center for Environmental Advocacy.

“We’ve got to get the science right. Especially when the stakes are this high,” Strand told reporters. “Agencies can’t make informed decisions unless they’ve got good science available on the important issues. And Minnesota citizens can’t have confidence in those agency decisions if they’ve got the science wrong.”

Paula Maccabee, an attorney for WaterLegacy, disputed PolyMet’s and DNR’s interpretation of the EPA’s comments, saying the federal agency raised serious concerns about mercury, the adequacy of containment measures, impacts on wetlands and other issues that won’t be simple to address.

PolyMet supporters say the project it will bring badly needed jobs and development to northeastern Minnesota. But the critics say copper-nickel mining poses new threats because the nonferrous metals are locked in sulfide-bearing minerals that can leach acid and other pollutants when exposed to air and water.

The review has generated an unusually high level of attention. More than 49,000 comments have been filed since December.

The DNR isn’t sure how long it will take to digest all the comments and produce the document, Niskanen said.

“Suffice to say we’re going to do this right and not going to do it fast,” he said. “We’ll take as much time as needed to come to the best final environmental impact statement as we can.”