PolyMet Permit to Mine & Dam Safety Permits

What are the permit to mine and dam safety permits?

The Permit to Mine is the primary permit issued by the Minnesota Department of Natural Resources (DNR) under state law to allow for the construction and operation of a nonferrous sulfide mine. This is the permit intended to require alternative technologies and designs to avoid and mitigate environmental harm, to provide for reclamation after mining is done, and to protect taxpayers from costs for remediation or cleanup.

Dam Safety Permits are also issued by the DNR under state law. Dam Safety Permits are intended to ensure that dam designs are safe and that dams are sited on solid foundations and in locations that minimize harm to the environment. The proposed PolyMet project required two dam safety permits: one for the tailings storage facility, which would contain wastewater and wet slurry tailings; and a second for toxic liquid hydrometallurgical waste from plant processing.

St. Louis County 2016 aerial image of existing site (south view of tailings mound and seepage below) where PolyMet plans to store its sulfide mine tailings. Photo by Jonathunder.

What’s their current status?

The DNR granted PolyMet a Permit to Mine and a Dam Safety Permit for both the tailings waste facility and the hydrometallurgical waste facility and denied requests for a contested case hearing on the permits on November 1, 2018.

WaterLegacy and our allies appealed from DNR’s PolyMet permit decisions on December 3, 2018. As a result of various legal motions and briefs, the Minnesota Court of Appeals stayed the DNR’s PolyMet permits on October 23, 2019.

On January 13, 2020, the Court of Appeals issued an opinion overturning the PolyMet Permit to Mine and Dam Safety permits. That decision was appealed by PolyMet and the DNR to the Minnesota Supreme Court, but the DNR PolyMet permits remain suspended, and no construction can take place while the court process is ongoing.

On April 28, 2021, the Minnesota Supreme Court issued an opinion reversing the PolyMet Permit to Mine and requiring a contested case hearing on an issue pertaining to control of pollution at the tailings basin. The Minnesota Supreme Court decision did not reverse the Dam Safety Permits.

What’s the history of the permits?

Draft Dam Safety Permits

The DNR proposed a draft Dam Safety Permits for the PolyMet tailings facility (Permit 2016-1380) and hydrometallurgical residue facility (Permit 2016-1383). WaterLegacy submitted comments opposing these PolyMet draft Dam Permits, along with 23 exhibits on October 16, 2017, emphasizing that:

  • PolyMet has not performed studies of the potential hazards that would result from dam failure at its proposed Flotation Tailings Basin (FTB) or Hydrometallurgical Residue Facility (HRF) dams.
  • PolyMet’s dam break analysis is inadequate… PolyMet’s meager analysis ignores the greatest threats posed by the failure of its proposed tailings waste dam: downstream water quality, public health, safety, welfare and the environment.
  • For the hydrometallurgical residue facility, “The soft ground beneath the proposed residue facility consists of up to 30 feet of slimes, peat, and tailings concentrate. This will not be an adequate foundation… The liner could deform and fail.”

Draft Permit to Mine

The DNR proposed a draft Permit to Mine for the PolyMet sulfide mine and processing plant on January 5, 2018.

On February 27, 2018, WaterLegacy filed Objections to the Permit to Mine and a Petition for Contested Case HearingWaterLegacy also filed 55 exhibits, posted in three separate batches (Exs. 1-39) (Ex. 40) and (Exs. 41-55) along with declarations of three Minnesota property owners who would be directly affected by tailings pollution seepage and possible dam failure. 

WaterLegacy’s Objections to the Permit to Mine and Petition for Contested Case Hearing made the following key points: 

  • The Permit to Mine is vague, unenforceable, and has no term limit to end mining, complete reclamation, and protect water quality.
  • PolyMet’s proposal to “capture” polluted seepage from a huge unlined waste rock pile and the unlined tailings waste storage facility are completely unproven and will not work.
  • PolyMet’s proposed tailings waste facility is located on wetlands and streams, shown in the historic map below, increasing routes for pollution of surface water and dam instability.
Historic map of wetlands and streams beneath the proposed PolyMet tailings basin and the existing LTV Steel Mining Co. tailings basin. The tailings basin outline (magenta) was superimposed by geologist J.D. Lehr.
  • Multiple faults and fractures at the PolyMet mine site and plant/tailings site, shown on the map below prepared by PolyMet’s own consultants, will exacerbate water pollution.
Bedrock Geology Large Figure 1 from Barr 2014b, FEIS reference study.
  • The soft and unsound foundation proposed for PolyMet’s hydrometallurgical wastes, with high concentrations of mercury, other toxic metals, and sulfate, is likely to lead to liner deformation and failure hidden beneath toxic wastes.
  • The foundation for PolyMet’s proposed tailings dam contains peat and slimes, contributing to instability, as illustrated below in PolyMet’s Application for a Permit to Mine, Figure 10-3.
Diagram from PolyMet’s Permit to Mine application.

Mount Polley tailings dam failure in August 2014. Photo from Jonathan Hayward/Canadian Press.

  • Financial assurance proposed in the Permit to Mine would not protect taxpayers.
  • An open and public contested case hearing before an objective administrative law judge is needed to fairly resolve disputed questions of fact.

Despite WaterLegacy’s objections, objections from Tribes and other groups and over 14,000 public comments, the DNR approved final Dam Safety Permits and the Permit to Mine for the proposed PolyMet copper-nickel mine on November 1, 2018. None of the critical issues raised in WaterLegacy’s comments were resolved in the PolyMet permits approved by DNR. DNR denied a contested case hearing.

Learn about the Appeal and the status of the case.