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is substantially higher. Copper is present in the Terry Tunnel reference water, <br />whereas It was not present in the ground water at the American Tunnel level in <br />consistently detectable concentrations. <br />MINTEQA2 calculations show the Terry Tunnel reference water to be at equilibrium <br />or oversaturated with most of the major rock-forming minerals that are present in the <br />country rock at that level. The impounded water is expected to be somewhat <br />unsaturated with respect to calcite. The overall reaction with country rock should be <br />minimal and will probably decrease matrix permeability with time. The lower sulfate <br />concentration of the Terry Tunnel reference water (relative to the American Tunnel <br />reference water) is offset by correspondingly elevated concentrations of metals. <br />Consequently, the Terry Tunnel reference water is also essentially at equilibrium with <br />major ore minerals and should be non-reactive with them along the migration path. <br />There may be some dissolution of rhodochrosite, which would further neutralize the <br />water and increase its buffering capacity, <br />Dilute, oxidized surface water that may enter the mine workings should be decreased <br />in the future as a result of surface water diversions under construction above the mine <br />workings. Any such water that does enter is expected to be driven toward reference <br />water composition by dissolution of ore minerals it comes in contact with along the <br />flow paths. <br />~unnv\wP'~Ir~d122511Mr1997 APB 64 <br />N:I SIRI011 HYDRO-SERRCH <br />