The Yankee Doodle Tailings Impoundment (YDTI) is currently permitted to a maximum crest elevation (EL.) of 6,450 feet (ft). The EL. 6,450 ft embankment provides sufficient tailings storage capacity to support mining and ore processing until approximately 2034. Montana Resources, LLC (MR) has prepared a permit amendment application (the 6,560 Amendment Application) to facilitate continued operation of the mine thereafter, with time to construct the next embankment lift, by aligning approval for tailings storage at the YDTI with the remaining ore reserves. The IRP issued their Report on the Design Document for the expansion, with final permit modification currently under review by the Department of Environmental Quality (DEQ).
Design Documents
- 6560 Amendment Design Document Cover Letter (PDF, 1 MB)
- Climate Conditions Report (PDF, 6 MB)
- Seismic Hazard Assessment Update (PDF, 16 MB)
- Design Basis Report (PDF, 10 MB)
- Evaluation of Tailings Management Technology (PDF, 20 MB)
- Life of Mine Design Report (PDF, 43 MB)
- Stability Assessment Report (PDF, 68 MB)
- Failure Modes and Effects Assessment (PDF, 9 MB)
- Tailings and Water Management Report (PDF, 35 MB)
- Water Balance Model Report (PDF, 12 MB)
- Dam Breach Inundation Study (PDF, 51 MB)
- Construction Management Plan (PDF, 4 MB)