Issues with the PD Sierrita Mine
1) Tailings seepage with sulfate from tailings impoundments:
Gold and silver and copper are no longer lying around on the ground and in rivers waiting to be picked up or panned. The days of following a rich vein to extract ore with high percentages of desirable metals have faded. Mining is now dependent on heavy mechanical technologies—it's a dirty business. Mammoth diggers and trucks dig up holes in the ground up to 3 miles wide and almost as deep. The rock that is considered useable—sulfide rock in this area, which is .3% cooper —is taken to the mill to be crushed to dust, then the dust is put into a solution with toxic chemicals to separate out desired copper and molybdenum, using large amounts of water. The slurry with its toxic chemicals and heavy inorganic metals that are primary contaminants are then put in unlined tailings impoundments and left to seep into the groundwater.
Tailings Pond Composition
2) Radioactive Chemicals present in tailings
plus 1999 EPA report on Cyprus-Sierrita Mine
Comparisons of Radioactive Chemicals along Impoundment and off-site Monitoring Wells
3) Use of toxic chemicals
4) Sulfuric acid spills
Correlation of dates of acid spills and spikes
5) Tailings dam safety
6) Reclamation/Clean-up--Other states require bonds
7) Acid mine drainage
8) Hazard of acidic/toxic ponds to wildlife?