Our numeric hydrologic model shows that any water table changes affect only the area of the mine itself with noticeable drawdown only in the part of the bedrock hydrologic system containing the mine. Continuously backfilling the mine with cemented tailings reduces the extent of drawdown as mining advances. The water table will return to normal on completion of mining.
Information Type FAQs
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.
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.
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.
No, we will have a lined pad for temporary storage of waste rock while we dig the underground tunnel to reach the copper deposit until the double lined cemented tailings facility (CTF) is completed. Once the CTF is completed, all temporarily stored waste rock will be trucked to the facility. Some of it will be ground up finely enough to use as a protection layer to prevent larger rock pieces from puncturing the 100 mil geo-textile liner. When mining starts, all the waste rock is covered with cemented tailings. Finally, Sandfire’s reclamation plans ensure that no waste rock piles will be left on surface when mining is complete. This is a much different outcome than how most historic mines were left, some of which developed metal leaching from acid mine and rock drainage.Read More
No, our system of cemented paste backfill underground ensures none of the rock walls stay exposed to oxygen long enough to allow a release of metals. Once the cemented paste backfill is placed underground water movement returns to pre-mining levels. All water from underground will be either used in the mill process or treated within the Reverse Osmosis Water Treatment Plant prior to release back to the environment through the underground infiltration system.
We measure the pH of several different types of water. In the future mine area, surface water pH ranges from 6.9 to 8.5 (neutral to slightly alkaline), and ground water pH ranges from 6.2 to 7.1 (near neutral). Water from the reverse osmosis water treatment plant will have a pH between 6 and 9 (slightly acidic to moderately alkaline), a range that is similar to surface waters. The small amount of water that may be pumped from the cemented tailings facility could have a pH as low as 2, but it will be pumped into the much larger volume of water in the process water pond with a pH of 9 to 10, where it will be neutralized.
No, Sandfire has carefully designed the Black Butte Copper Project to protect all water resources and prevent any acid mine drainage. Acid mine drainage, by definition, happens when water flows over or through sulfur-bearing materials that is exposed to air, oxidizes becomes acidic, and carries toxic materials to surface water ways. To prevent this, Sandfire has designed our underground mine so that all entrances are close to 200 feet above the ground water level and over 300 feet above the underground mine workings in the copper deposit. Water cannot run uphill out of the mine so nothing can ever drain/flow out of the mine. This ensures that terrible accidents like the one on the Animas River in Colorado cannot happen at our Black Butte Copper Project.Read More
Is there concern for potentially acid generating rock (PAG) creating acid mine drainage at Black Butte?
There are sulfide minerals present in copper mining which can create acid when they oxidize. Fortunately, the Johnny Lee deposit is completely encased by rocks having a high concentration of carbonate, which acts as a buffering (or neutralizing agent) against acid. In our intensive test work, these minerals have successfully neutralized the acidity that has been produced by sulfide oxidation. Tintina is taking every measure to minimize acid production, and the large volumes of carbonate in the mined rock and its host rocks are expected to be a great help in managing potentially acid generating rock (PAG). Mine operations around the world developed in carbonate host rocks are very successful in protecting the environment.
Potentially Acid Generating rock (PAG) rock is rock that when oxidized by surface weathering may form acid which can then leach metals. Leached metal ions can be harmful to fish and other aquatic life. PAG must and will be managed to inhibit oxidation in order to minimize any possible acid production. As an added precaution, all left over rock, PAG and NAG (non-acid generating rock) will be stored in the Cemented Tailings Facility.