DEQ completes EIS on expansion of mine tailings impoundment near Butte
HELENA – The Montana Department of Environmental Quality has completed the Final Environmental Impact Statement for Montana Resources’ request for a mine permit amendment to raise its Yankee Doodle Tailings Impoundment northeast of Butte.
Montana Resources is proposing to raise the impoundment’s western embankment to accommodate tailings storage for future mine production. DEQ has identified Montana Resources’ Proposed Action as the agency's preferred alternative, with an added stipulation: That Montana Resources consult with the Butte Mine Flooding Operable Unit (BMFOU) Consent Decree parties to identify strategies that would allow reclamation to begin sooner after the impoundment has served its purpose and is closed.
The operating permits and associated bond would be managed following the operation and reclamation plans described in the Proposed Action, unless further modifications were made following consultation with BMFOU parties and approval by the United States Environmental Protection Agency.
DEQ will set forth its final decision and rationale in its Record of Decision, the legal document that provides the rationale and any special conditions surrounding the decision or its implementation. DEQ must issue the ROD no less than 15 days from the transmittal of the Final EIS to the public, the Environmental Quality Council and the Governor’s Office.
Yankee Doodle is a pond-like impoundment that holds water and tailings, the waste left over from ore extraction at Montana Resources’ copper and molybdenum mine. As tailings slurry is deposited into the impoundment, water separates and forms a pond at the north of the facility, while the solid tailings settle out and form a dry “beach” area near the embankments. The tailings and water surfaces rise due to mine operations.
The purpose of Montana Resources’ proposal to raise the impoundment’s western embankment is to accommodate additional tailings storage for future mine production. The project would raise the embankment to the elevation of 6,450 feet, extend the northern boundary of the impoundment and add other facilities to support the project.
Montana Resources applied for the permit amendment in October 2017 under provisions of the Montana Metal Mine Reclamation Act. DEQ determined the Montana Resources amendment application was complete and compliant and issued a draft approval on Aug. 31, 2018.
The EIS process began in the fall of 2018 with a public comment period and a public meeting in Butte, where DEQ sought input from the public as well as federal, tribal, state and local governments to help identify potential impacts and possible alternatives to be considered in the EIS.
DEQ appreciates the public’s participation in the Montana Resources EIS Project. The Final EIS is available at: deq.mt.gov/Public/eis