MPCA - Quarterly PolyMet permitting update

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Quarterly Update

The following is a summary of the Minnesota Pollution Control Agency’s (MPCA) activities during the second quarter 2017 regarding applications submitted by Poly Met Mining, Inc. (PolyMet) for its proposed NorthMet mine and processing plant.

The MPCA and Minnesota Department of Natural Resources (DNR) send out quarterly messages summarizing activities and documents added to the project website in the previous quarter. For the most up to date information, check the state’s PolyMet web portal ( and MPCA’s project website ( It is also the MPCA’s future goal to use this email subscription list to notify the public in advance of any permit comment period or other opportunity for public participation.

Air quality permit

During this quarter, the MPCA continued to review the reports and elements of the permit application. MPCA completed its review of PolyMet’s Air Emissions Risk Analysis (AERA) modeling submitted in the application. The AERA uses a scientific process to estimate the potential human health risks from air toxics emitted from a facility. MPCA concluded that PolyMet’s modeling was accurate and risk estimates do not exceed facility risk guideline values.

The following AERA-related documents are posted on the project website: workplans, workplan approval, modeling results (in the permit application), and list of errata for the AERA report. Because of their large size and file format, the AERA modeling files are not posted online but are available by request at:

Individual wastewater NPDES/SDS water quality permit

MPCA continues to review PolyMet’s NPDES/SDS water quality permit application.  Work is ongoing in the areas of antidegradation, permit limitations, and other permit requirements.  MPCA continues to maintain routine conversations with EPA during the review process.  

Construction stormwater general NPDES/SDS water quality permit

No applications for Construction Stormwater General Permits were received this quarter.

 401 water quality certification

MPCA continues to coordinate with DNR and US Army Corps of Engineers in reviewing the request and determining appropriate wetland mitigation and potential water quality certification requirements. The 401 certification request and related application materials are available on the project website.

You are receiving this message as a subscriber to the PolyMet email notification list.  This list is hosted by the DNR. It is used jointly by MPCA and DNR to provide regular updates and share information about key steps in the permitting/certification processes, including opportunities for public comment.