Three more draft permits were released by the state for review. So now nine draft permits have been released since we filed the permit applications more than a year ago.

Let’s look at the latest steps forward:

On September 15, the Minnesota Department of Natural Resources released two draft dam safety permits and the draft public waters work permit. Those three are now in a 30-day public review and comment period.

The draft dam safety permits establish the design, construction and operating parameters to ensure long-term, safe, stable operations of facilities that hold water. PolyMet will have two facilities that impound water: an existing tailings basin and a new hydrometallurgical residue facility.

About the tailings basin

A tailings basin is a highly engineered structure and probably the most tested and studied aspect of the entire project – where finely ground rock, called tailings, is permanently stored after it has been mined and crushed and the economic metals have been removed. As with other aspects of the project, we have taken the design, and our plans to construct and operate the tailings impoundment, very seriously to ensure a safe and stable structure.

Here are some key aspects of the tailings basin:

  • The independent environmental review of the project by state and federal agencies shows the project as designed can be protective of water and other natural resources.
  • Water in the existing basin (left from legacy iron ore processing) is in the pH neutral range, meaning it’s non-acidic. Testing shows that the water and tailings will remain non-acidic throughout operations and after our project closes.
  • Extensive testing on basin stability, reviewed by a number of independent experts, has determined the basin is stable and capable of safely storing additional tailings over the permitted life of the mine.

See our tailings basin stability fact sheet for more detailed information.

About the other recently released permit

The new hydrometallurgical residue facility will impound water and solids from the hydrometallurgical processing plant, and will have a double liner containment system. The public waters work permit is to extend a culvert to widen a road between the plant and mine sites.

Water appropriations permits update

The 30-day public review and comment period for six draft water appropriations permits has now closed.

 Status of other permits applications

Other permit applications currently under review by the state include:

– Water quality permit (National Pollutant Discharge Elimination System/State Disposal System or NPDES/SDS permit)

– Air emissions permit

– Permit to Mine

Track our permitting process

We’ll keep you posted, and you can follow all PolyMet project draft permits and applications on this DNR and Minnesota Pollution Control Agency website.

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