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ST. PAUL, Minn. (AP) - Minnesota state officials on Friday delivered a mammoth, final environmental review for a proposed copper-nickel mine, saying the project as designed would meet state standards for protecting the environment and human health.
The highly anticipated 3,500-page document stipulated that wastewater from the mine would have to be treated indefinitely to prevent pollutants from escaping. And it said PolyMet Mining Corp. would have to put up money to make sure cleanup costs are covered for as long as necessary after the mine closes.
"We have really turned this project upside down, inside out and backward and forward to take a look at it," said Tom Landwehr, commissioner of the Department of Natural Resources. Officials said the $20 million spent so far is the most expensive such screening in state history.
The PolyMet project has been fiercely opposed by environmentalists who worry about pollution ruining waters near the mine's northeast Minnesota location and perhaps even reaching the Boundary Waters Canoe Area Wilderness. Supporters argue that the mine would bring jobs and economic development to an area of the state that sorely needs it as taconite mining has declined.
State officials say the document isn't a recommendation for or against the project. The release starts a 30-day public comment period that runs through Dec. 14. The DNR will rule by early next year if the study is adequate. The company can then start applying for about two dozen local, state and federal permits.
The review -- paid for by PolyMet -- was compiled by the DNR, the U.S. Forest Service and the U.S. Army Corps of Engineers to survey the effects if it allows the copper and nickel mining. Because of the complexity involved, the state agency issued 23 fact sheets to help the public decode the technical jargon.
The document updates a review issued nearly two years ago. Some of the changes reflect the 58,000 public comments on that version, which itself updated a widely criticized original environmental impact statement issued in 2009.
Kathryn Hoffman, an attorney at the Minnesota Center for Environmental Advocacy, said she's concerned that the department didn't seek independent verification of water-quality studies and said the state should brace for a new outpouring from opponents.
"The public has spoken," she said. "It's not too late to listen."
Landwehr said unless compelling evidence surfaces there will be a "high bar" to declare the study inadequate, which would trigger a new analysis.
The document says mine runoff would not reach the Boundary Waters Canoe Area Wilderness or Voyageurs National Park. Addressing an issue that surfaced late in the process, the regulatory agencies that prepared the document said they believe any northward flow from the site is unlikely, though they can't completely discount the possibility either. They said mitigation efforts can be implemented if they become necessary.
Major changes to the project resulting from the reviews include the addition of a reverse-osmosis water treatment system and a redesign to beef up the tailings basin, which holds leftover materials after the copper, nickel and precious metals are extracted from the ore. The document says PolyMet's tailings basin would be built to a significantly higher standard than the tailings basin that collapsed in an environmental disaster at the Mount Polley copper-and-gold mine in Canada last year.
Gov. Mark Dayton has said the ultimate call his administration will make on a "permit to mine" will be the biggest and toughest decision of his two terms. The project has caused divisions within his Democratic Party, splitting those who see its job potential and those who worry about environmental damage.
In advance of Friday's release, Dayton traveled to mines in South Dakota and Michigan to assess how those were undertaken and where they succeeded or fell short.
PolyMet has proposed extracting the minerals from an open-pit mine in Babbitt and reusing a former LTV Steel Mining Co. processing plant in nearby Hoyt Lakes that it bought from Cleveland Cliffs. The company predicts it will remove 533 million tons of ore and waste rock over the 20-year life of the mine.
PolyMet's president and CEO, Jon Cherry, in a statement, called the report's release a "huge milestone." He described the decade-long review as detailed and thorough.
The company added that the study "demonstrates that PolyMet can mine and process copper, nickel and platinum group metals in a manner that complies with the law, protects the environment and creates hundreds of high-paying jobs."
Mining Truth, a coalition opposed to the project, said in a statement it would review the document closely and deliver a response next week. It has questioned whether PolyMet can provide sufficient financial assurances for a proper cleanup if the company goes bankrupt.
Dayton has said he plans to seek legislative approval to hire an outside law firm to carefully review the company's finances ahead of his decision.