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.