Dam Safety Permit
PolyMet's NorthMet Mining Project

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On November 1, 2018, the DNR issued two dam safety permits for the 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.

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


Dam Safety Permits and Findings of Fact


Historic Permitting Information

The NorthMet project requires two dam safety permits for various construction and operation activities at the plant site.

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

DNR accepted written public comments on the draft dam safety permits from September 15, 2017 until October 16, 2017.

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 Applications

May 16, 2017 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) »

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