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~ ~ III IIIIIIIIIIIIIIII <br />INTEROFFICE COMMUNICATION <br />i7oC. Na>~2. ~w't(s ¢va~l~af~~K. o~ wait-e.r oj,.al,'~r cv-t` 93~o c(~,,.-~~ <br />--`--1 ¢ b .~ s~ e p s <br />DATE: August ] 0, 1998 '~ <br />TO: Steve Shuey _~y.y~ <br />FROM: Ham Posey C~j <br />RE: Bulldog Project, Mineral County, Permit M-77-215 <br />Thank you for the letter from Allen Cox of Homestake (29 July 1998) with <br />attached analytical results. Having examined the analytical results, I would offer a few <br />observations. <br />As I understand it, toe seeps DT-1 and DT-2 occur below the 9360 portal dump, <br />and are the ones we observed in the field on July 22. Both seeps have elevated metals <br />and somewhat low pH. At issue is whether these seeps contain groundwater from the <br />Bulldog mine or from the land-applied 9360 portal dischazge water. In that regard, it <br />remains to be learned whether groundwater has been affected adversely by exposure to <br />underground workings or whether the land-applied water grows contaminated as it flows <br />through the 9360 waste rock dump. <br />The chemical fingerprints of samples DT-1 and DT-2 aze remarkably similar. <br />Metals that aze significantly above detection limits have virtually the same <br />concentrations. The higher sulfate, TDS and conductivity in DT-1 is compatible with the <br />slightly higher pH, but the differences are actually minor. I would suggest these <br />represent waters from the same source collected at slightly different points on a flow path <br />and possibly very slightly affected by some dilution. <br />The field pH measurements appeaz to be in error. For solutions derived from <br />pyrite weathering, lab pH values aze typically lower than field pH, but not by more than <br />about 0.2 to 0.3 units. However, in this case, the reported field pH values differ by more <br />than 0.6 units. <br />As you have probably noticed, the concentrations of several metals -zinc, <br />cadmium and copper -exceed aquatic life-protective values. Additionally, the pH is too <br />low for sensitive aquatic species. <br />Given the high cadmium and manganese values of these waters, it may be prudent <br />to know whether these waters are used for drinking water anywhere in the azea. These <br />cadmium levels would be considered dangerous to humans in the short term, and the <br />manganese would be chronically toxic over the long term. <br />cc: Bruce Humphries <br />Allen Sorenson <br />Jim Pendleton <br />c ~\hhp\gencral\bullJUg <br />