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X__ iii iiiiiiiiiiiu iii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY ~ o <br />Department o(Natural Resources ,vim°-~ ~~ <br />Ne ;~ <br />1313 Sherman 51.. Room ? I S ~jp <br />Denver, CO 80:03 ~' ' <br />Phone: IJ031 866-3561 ' • tote <br />FA%: 13031 8328106 <br />Roy Romer <br />Governor <br />October 22, 1992 Michael B. Long <br />Division Director <br />Mr. Robert Weaver <br />O.C. Coal Mine <br />P.O. Box 539 <br />Gunnison, Colorado 81230 <br />RE: Suspension of Water Quality Sampling During Temporary Cessation, O.C. 1Vline, C- <br />80-002 <br />Dear Mr. Weaver: <br />During our telephone conversation on October 19, 1992 you said that you were unable to take <br />water quality samples at the Nu Mine and underground at the O.C. Mine because of accessibility <br />problems. The surface ownership of the Nu mine had changed hands and you are unable to get <br />right of entry. Also, underground access to the Hooded portions of the O.C. workings were <br />prevented by safety concerns with the closed mine. <br />Based on my review of past water quality monitoring data that you have collected at the mine, the <br />Division will allow you to suspend underground water monitoring during the mine's period of <br />temporary cessation. Should the sediment pond ever discharge, you must monitor the discharge as <br />required by your NPDES permit. You must continue to conduct quarterly pond inspections. <br />The underground water quality from the O.C. mine is good, and would be close to EPA Drinking <br />Water Standards for salinity. Electrical Conductivity, an indicator of salinity, as measured in <br />micromhos, was consistently around 600 to 750 with 3 exceptions of conductivities from I50 to <br />180 micromhos. The 3 exceptions may have been caused by sample mix ups at the lab. Water <br />monitoring does not show a negative trend to the water quality. I atn not concerned that <br />underground water is having a negative quality impact on the hydrologic balance. The pH is also <br />well within the good quality zone. <br />