Dam Safety Permit
PolyMet's NorthMet Mining Project

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The DNR opened a 30-day public comment period on draft dam safety permits for the proposed Poly Met Mining, Inc. (PolyMet) NorthMet mining project. DNR's Dam Safety Permit Program is required to regulate the construction, operation and maintenance of dams to protect public health, safety and welfare. The DNR regulates the construction and enlargement of dams, repair, alteration, maintenance, operation, abandonment and transfer of ownership through the dam safety permitting process. Minnesota Rules establish minimum standards and criteria for dam classification and regulation. These cover both initial permitting and ongoing regulatory oversight. These actions are administered and monitored by the DNR Dam Safety Unit. The proposed NorthMet project would require two dam safety permits for various construction and operation activities at the plant site. In addition to these two dam safety permits, the project would also need ten additional DNR permits, as well as several other state, federal and local permits and approvals in order to proceed.

DNR and external consultant Emmons Olivier Resources, Inc. (EOR) have completed a comprehensive review of the company's two dam safety permit applications. They also considered input from state, local and tribal governments.

One draft dam safety permit covers the proposed flotation tailings basin, which would be located on the site of the existing tailings basin of the historic LTV iron ore mine and would receive tailings (a mixture of finely ground waste rock and water). The second draft dam safety permit covers the proposed hydrometallurgical residue facility, which would receive residue (mostly gypsum) generated from a process that would use pressure and temperature reactions to extract additional precious metals beyond what can be achieved by the primary processing facility.

DNR accepted written public comments on the draft dam safety permits from September 15, 2017 until October 16, 2017. This public comment period is now closed.

The current public comment opportunity concerned only the two draft dam safety permits as well as the draft public waters work permit. DNR’s review of PolyMet’s other pending applications – permit to mine, including financial assurance proposals and the wetland replacement plan – is ongoing.

PolyMet’s dam safety permit applications along with DNR’s draft dam safety permits and fact sheet can be found below.


Where are we in the overall permitting process?

View timeline graphic (3 MB) »
View timeline text only (1 MB)   »


Draft Dam Safety Permits and Fact Sheet

Fact Sheet - Draft Dam Safety Permit Fact Sheet (1 MB) »


Permit-related Documents

State consultant reports
Added on May 16, 2017


Dam Safety Permit Application

Current Applications

Previous Applications


Reference documents

Final Environmental Impact Statement: NorthMet Mining Project and Land Exchange (link to final document webpage) »
Residue Management Plan v5 (40 MB) »
Geotechnical Data Package Volume 2 – Hydrometallurgical Residue Facility v6 (42 MB) »
Wetland Permit Application v2 (101 MB) »
Project Description v9 (22 MB) »
NPDES/SDS Permit Application Volume V – Tailings Basin and Beneficiation Plant (56 MB) »
Wetland Data Package v11 (42 MB) »
Plant Site Water Management Plan v5 (43 MB) »
Plant Site Water Modeling Data Package Volume 2 v11 (122 MB) »
Waste Characterization Data Package v12 (47 MB) »
Plant Site Air Quality Management Plan v7 (2 MB) »
Consideration of a West Pit Backfill Alternative Interagency Memorandum (1 MB) »