The former Tony M mine was designed as a random room and pillar operation with pillar extraction by a retreat system. The pillars are 136 ft by 136 ft and form a conventional room and pillar pattern.
The Tony M mine is accessed via a double entry system with two parallel declines spaced 50 ft apart on centres. The portals of the two 9 ft high by 12 ft wide main haulage ways are located on the northwesterly side of Shootaring Canyon near the south centre of Section 16 T35S R11E SLM with a sill elevation of approximately 4,546 feet above sea level (FASL). The declines follow a minus three percent grade (i.e., 3 ft/100 ft) along a trend of N22°W, and generally follow the long axis of the mineralized trend, extending approximately 10,200 ft from the portal. The declines intersected the natural water table approximately 5,300 ft from the portal.
Plateau developed over 18 mi of underground workings in the Tony M mine. In 1984, dewatering was suspended, and the Tony M mine was allowed to flood. When USEC abandoned the Tony M mine in the late 1990s, the portals were closed, and the ventilation shafts capped as part of mine closure and reclamation activities.
When Denison operated the Tony M mine from 2007 to 2008, several surface facilities were constructed, including a power generation station, compressor station, fuel storage facilities, maintenance building, offices, and dry facilities. An evaporation pond which was originally constructed when th ........