Information Center

Category Water & The Environment

Are there things we can do to enhance the fisheries?

Yes, we are looking forward to working with our conservation community to enhance the fisheries. This is an important area for cut throat restoration and we believe there are opportunities for us to assist in these important efforts. We have established a “stakeholders” group to listen to concerns of the conservation community and to get their input on conservation enhancements.

How much water does Sheep Creek supply to the Smith River?

The estimated average base flow in Sheep Creek at the project is 15 cfs and at its confluence with the Smith River is 30 cfs during low flow periods of November through March. The average base flow in the Smith River during this period is approximately 90-100 cfs. Sheep Creek provides approximately 10% of the flow passing by the project and 30% of the flow in the Smith River at their confluence.

What happens to the water once it is pumped out of the mine workings?

All of the water not consumed by the milling process at the mine will go through the reverse osmosis (RO) water treatment plant and then be returned immediately back to the groundwater system through an underground infiltration system. The consumptive use rate of the mine is 210 gpm; resulting in any additional water pumped being returned directly to the groundwater system (210-290 gpm).

How much water will be pump from the mine?

Estimated dewatering rates pumped from the mine range from 220 gpm to 500 gpm as the mine access is developed. The dewatering rate during full operation is estimated between 420 and 470 gpm. All but the 210 gpm of water needed for use in the milling process returns back to the groundwater system via the underground infiltration system after treatment by the reverse osmosis water treatment system.

Will our “cone of depression” extend to the Sheep Creek alluvium?

The cone of depression over the mine area extends slightly into the Sheep Creek alluvium with the largest drawdown near the western and southwestern edge of the alluvium. The drawdown in the alluvium adjacent to Sheep Creek is one foot. This indicates that the drawdown in the alluvium has the potential to slightly deplete flows in Sheep Creek. The numerical model shows that the potential maximum depletion in Sheep Creek is approximately 0.45 cfs (~200 gpm). The base flow (lowest yearly flow) of Sheep Creek is 6700 gpm, so our maximum effect on Sheep Creek could be 3% of its flow. We will be replacing more than this with our mitigation plan.Read More

Will all water be treated?

Sandfire has designed the BBCP to completely protect Sheep Creek and its fisheries, and in turn the Smith River and all the recreational uses and businesses supported by it. The operation will treat all water released from site to meet Montana’s strict non-degradation standards and return the treated water straight back into the ground water system through an underground infiltration system buried 6-8 feet in highly permeable ground.

Will nitrates be used and if so how will they be handled?

Yes, the mining process will use nitrates as underground in explosives. The environmental will be protected by the reverse osmosis water treatment process which will ensure we are able to meet the non-degradation discharge standards set by the Montana Department of Environmental Quality by removing nitrates from the water.

Will there be any perpetuity issues on site with treatment of water?

Sandfire has designed the Black Butte Copper Project for quick reclamation at the end of mine life with no need to treat water in perpetuity on site. We have chosen a cemented tailings facility (CTF) because it offers the highest environmental protection and quickest reclamation of any tailings facility designs we studied. Because the CTF will have no pond of standing water during operations, once the mine closes Sandfire will cover the facility with a 100 mil HDPE liner, weld it to the lower double liner, and cover the liner with 4 or more feet of fill, top soil, and grass. The pump will remain in the CTF to treat and test the small amount of water that may seep until the facility stabilizes and monitoring will continue as long as required by the DEQ.