The DNR has 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. The NorthMet project will 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 will 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) completed a comprehensive review of the company's two dam safety permit applications. They also considered input from state, local and tribal governments.
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.
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 dam safety permits, along with supporting documentation, can be found below.
Where are we in the overall permitting process?
Dam Safety Permits and Findings of Fact
- Permit 2016-1380: Flotation Tailings Basin (1 MB) »
- Permit 2016-1383: Hydrometallurgical Residue Facility (1 MB) »
- Dam Safety Findings of Fact Permits 2016-1380 and 2016-1383 (2 MB) »
- Permit 1981-2100: Tailings Basin Transfer (1 MB) »
- Dam Safety Findings of Fact Permit 1981-2100 (1 MB) »
Draft Dam Safety Permits and Fact Sheet
- Draft Permit 2016-1380: Flotation Tailings Basin (1 MB) »
- Draft Permit 2016-1383: Hydrometallurgical Residue Facility (1 MB) »
Fact Sheet - Draft Dam Safety Permit Fact Sheet (1 MB) »
State consultant reports
Added on May 16, 2017
Dam Safety Permit Application
- Cover Letter - Flotation Tailings Basin Application (6 MB) »
- Flotation Tailings Basin Application (203 MB) »
- Updated Flotation Tailings Basin Instrumentation and Monitoring Plan (15 MB) »
Also found in the above application as Attachment D of Appendix A
- Updated Flotation Tailings Basin Contingency Action Plan (1 MB) »
Also found in the above application as Attachment F of Appendix A
- New Flotation Tailings Basin Template Pilot Test Plan for Bentonite Amendment of Tailings (1 MB) »
Also found in the above application as Attachment I of Appendix A
- Cover Letter - Hydromet Residue Facility Application (3 MB) »
- Dam Safety Permit Application - Hydromet Residue Facility (45 MB) »
- Cover Letter - Flotation Tailings Basin Application (1 MB) »
- Dam Safety Permit Application - Hydromet Residue Facility (42 MB) »
- North Dam Buttress Modification (2 MB) »
Added on January 11, 2017
- Cover Letter - Hydromet Residue Facility Application (1 MB) »
- Dam Safety Permit Application - Hydromet Residue Facility (24 MB) »
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) »