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iii iiiiuiiiiiiiiii ~ STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Depanmenl of Natural Resources 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: 1303) 866-3567 FA%:1303)83?-8106 February 15, 2000 To: Jim Dillie From: Harry Posey ~--~'(//" J~ Subject: Battle Mountain inquiry Your note of 2/l4/00 asked: .~~.at~ DIVISION OF MINERALS GEOLOGY RECLAMATION MINING•SAFETY R~II Owens Governor Greg E Watcher EnecuOve Director Michael B. Long Drvis~an Dveaor "As sulfate levels get nearer the water quality standards (250 ug/L) in the w@st pit, will there be a problem with any other metals (other than manganese) in the west pit backfill?" It is my understanding that, relative to drinking water standards, some of the wells in the West Pit and/or the Pink Gneiss Pit have elevated concentrations of manganese, cadmium and arsenic. Not all of the wells have elevated values. It is further understood that the multi-faceted water treatment currently being applied to waters of the West Pit remove these metals plus sulfate. Because the current water treatment system generates treated water that meets in-stream standards levels, and on the presumption that such treatment will not be altered appreciably for the duration of water treatment, it should be concluded that average concentrations of metals in the west pit will not increase during the period of treatment. After West Pit water treatment ceases, I would anticipate that precipitation flushing through the West Pit unsaturated zone will cause sulfate levels to increase slightly due to dissolution of gypsum originally present in the Santa Fe Alluvium. I would not anticipate however any significant rise in metals. Infiltration of untreated water from the Pink Gneiss pit, if any, might also cause metal concentrations to increase. Except for these circumstances, I would not any appreciable increase in dissolved metals in the West Pit. cc: Jim Stevens Bruce Humphries.