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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.

Through metallurgical testing we have learned that nearly all the rock on the waste rock storage piles will be ‘non-acid generating’. If rain or snowmelt does leach a little metal from the waste rock in the this short period of temporary storage, that water will be collected on the lined pad and run through the reverse osmosis water treatment plant which will collect any metals in the water and leave it pure for return to the groundwater system.