The Yankee Doodle Tailings Impoundment (YDTI) was originally constructed in 1963 and comprises a valley-fill style impoundment created by a continuous rockfill embankment that, for descriptive purposes, is divided into three sections: the North-South Embankment, the East-West Embankment, and the West Embankment.
These embankments are the:
- North-South Embankment – The North-South Embankment forms the eastern to southeastern limb of the YDTI and runs approximately north to south in orientation. The North-South Embankment abuts onto the base of Rampart Mountain, forming the eastern battery limit of the Montana Resources mine site.
- East-West Embankment – The East-West Embankment forms the southwestern limb of the YDTI and runs approximately east to west in orientation. The East-West Embankment is constructed upstream of Horseshoe Bend and Berkeley Pit.
- West Embankment – The West Embankment forms the western limb of the YDTI and runs approximately north to south in orientation. The West Embankment is constructed into the side of the West Ridge and forms the western battery limit of the facility.
In addition to tailings storage, YDTI performs two other key functions:
- Operational storage for process water used in the milling and flotation circuit; and
- Water treatment as part of the Butte Mine Flooding Operable Unit (BMFOU) remedy.
The design, construction, operation, maintenance, and surveillance of the YDTI involves a multidisciplinary team of professionals. The team works closely together to achieve the fundamental objective of ongoing continuous improvement of the safety of the impoundment. Mine operations are governed by a mine permit issued by the Montana Department of Environmental Quality (DEQ) pursuant to the terms of the Metal Mine Reclamation Act (MMRA).