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 first quarter 2017 regarding applications submitted by Poly Met Mining, Inc. (PolyMet) for its proposed NorthMet mine and processing plant.

The MPCA and 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 completed its review of PolyMet’s Class I air modeling report and  approved it. Now MPCA will use the report to draft permit conditions that ensure continued protection of the air quality in nearby Class I areas, including the Boundary Waters Canoe Area Wilderness. MPCA continues to review the other air modeling reports and elements of the permit application. The MPCA posted the following to the project website: a Class I modeling list of errata, AERA modeling list of errata, and Class I modeling report approval.

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

On February 7, 2017, PolyMet submitted an application for a Construction Stormwater General Permit for geotechnical investigations at the NorthMet Project plant site and tailings basin. Geotechnical investigations are very common prior to construction of commercial buildings, apartments, and road projects; examples include the Vikings stadium, the Saint Croix River Bridge, and the Highway 53 project near Virginia. Since these activities disturb more than one acre of land, a Construction Stormwater General Permit is required before starting the activity.

The purpose of PolyMet’s geotechnical work is to investigate and characterize geological conditions at the site prior to construction and mining operations. This includes such activities as borings and test pits to determine soil characteristics and depth to bedrock, and installation of monitoring wells. Coverage under this application only authorizes activities related to the geotechnical work; it does not authorize construction or operation of the processing facility, mine pits, or other construction activities.  

Coverage under this permit was effective on March 9, 2017. MPCA approved PolyMet’s Stormwater Pollution Prevention Plan (SWPPP) for the geotechnical work, which becomes an enforceable part of the permit. 

401 water quality certification

MPCA continues to coordinate with DNR and US Army Corps of Engineers in reviewing the request. The 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 Department of Natural Resources (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.