Several leading environmental groups this week asked for an administrative court review of Minnesota's plan for the state's first proposed copper nickel mine, saying it violates state law and won't protect taxpayers from long-term environmental problems.

The request for a contested case hearing before an administrative law judge was expected, and is typical with big and controversial projects such as PolyMet Mining Corp.'s proposed open-pit mine near Hoyt Lakes. Barb Naramore, assistant commissioner for the Minnesota Department of Natural Resources, said "we will carefully consider the petition."

Under state law, the DNR can decide whether to submit the petition to an administrative court, a step that would introduce a new delay in what has already been a lengthy regulatory review. If the DNR says no, the environmental groups can appeal to the Minnesota Court of Appeals.

PolyMet officials said in a statement they are confident that they can build and operate the mine while protecting Minnesota's natural resources. "The same thoroughness that went into the development of the environmental review was applied in the preparation and drafting of the permits," they said.

The petitions say there are many issues where material facts are in dispute and must be resolved before the state can issue PolyMet a permit to mine.

One is the safety and stability of an old tailings basin where PolyMet plans to store mining residue, which critics say is far more toxic than the tailings produced by the taconite mine for which it was created. The environmental groups called the structure "a disaster waiting to happen."

Their petitions also argues that the state's "financial assurance" plan, designed to protect taxpayers from long-term environmental costs, is inadequate because the mine won't produce sufficient revenue to cover PolyMet's obligations to the state.

One petition was filed by WaterLegacy, and the other jointly by the Minnesota Center for Environmental Advocacy, the Center for Biological Diversity and the Friends of the Boundary Waters Wilderness.