Information Center


Category Water & The Environment

Will there be leaching of metals in the waste rock piles into the groundwater?

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

Will there be leaching of metals underground?

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.

What will the pH of the water be?

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.

Will the project create acid mine drainage?

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.

What is Potentially Acid Generating rock (PAG)?

Potnetially 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 gereating rock) will be stored in the Cemented Tailings Facility.

What is Non Acid Generating rock (NAG)?

Non Acid Generating rock (NAG)  is rock that in surface weathering/oxidizing conditions produces no acid. Our current test results show that most of the excess rock resulting from mining at Black Butte is non-acid generating. This is good news as this rock contains sufficient carbonate minerals to neutralize any potential acid generation from mineralized material.

What elements of concern are in the rock that we will need to treat?

Based on extensive testing of the surface and groundwater of the area, which naturally leach metals from the surrounding rock, and the results of humidity cell tests on waste rock and cemented tailings, the most persistent elements exceeding groundwater and surface water standards are arsenic (As), selenium (Se), thallium (Tl), and strontium (Sr). Other elements, including copper (Cu), lead (Pb), nickel (Ni), mercury (Hg), cadmium (Cd), and zinc (Zn), could be of concern if waste rock were not properly managed. Fortunately, responsible management minimizes the amount of leaching of these elements into site water during the operation, and reverse osmosis water treatment removes all of them.

How will water be protected?

We take protecting all the water resources seriously. Sandfire’s professionals chose the tunnel entry location specifically because it is almost 200 feet above the water level. In order to keep water from leaving the mine and mixing with creek water, all planned openings or entry points to the mine (including air ventilation and escape routes) are located far above the water table. Sandfire’s professionals chose the tunnel entry location specifically because it is almost 200 feet above the water level.Read More

What elements of concern are in the rock that we will need to treat?

Based on extensive testing of the surface and groundwater of the area, which naturally leach metals from the surrounding rock, and the results of humidity cell tests on waste rock and cemented tailings, the most persistent elements exceeding groundwater and surface water standards are arsenic (As), selenium (Se), thallium (Tl), and strontium (Sr). Other elements, including copper (Cu), lead (Pb), nickel (Ni), mercury (Hg), cadmium (Cd), and zinc (Zn), could be of concern if waste rock were not properly managed. Fortunately, responsible management minimizes the amount of leaching of these elements into site water during the operation, and reverse osmosis water treatment removes all of them.