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Mountain Coal Company 1997 Annual H}'drolog}' Report West E/k Mine <br />Mine Water Management Activities <br />North Fork Water Rights <br />MCC diverts water for in-mine processes and potable uses from the North Fork via the Mount <br />Gunnison Pipeline water right. Approximately 372 acre-feet of water were diverted using this <br />water right during WY97. <br />Because the Mount Gunnison Pipeline is a relatively junior water right, it is often called out of <br />priority during the late summer and early fall. However, in WY97, there were no calls placed on <br />the North Fork. Also, primazily due to the fault inflows, MCC was a net contributor of <br />approximately 219 acre-feet of water to the North Fork during WY97. <br />Sanitary Wastewater <br />MCC maintains an activated sludge wastewater treatment plant (WWTP) to handle sanitary <br />wastewater generated by the West Elk Mine. The WVl'TP has been operating since 1982. <br />Discharges aze made in accordance with CDPS Permit No. CO-0038776. The treatment facility <br />has a good compliance history. <br />As shown on Figure 6, the WWTP discharges into pond MB-ZR, where the effluent mixes with <br />stormwater runoff and mine water stored in the pond, prior to discharge to the North Fork. Both <br />discharges from the WWTP and pond MB-2R must be monitored by MCC as required by the <br />. CDPS permit. The regulated parameters that apply to the WWTP are shown in Table 6. The <br />discharge designation for the WWTP is 007A, and the discharge designation for pond MB-2R is <br />004A. <br />As shown for the WWTP (007A) on Table 7, the maximum concentrations during WY97 for all <br />regulated parameters were less than the corresponding CDPS limitations (Table 6). There were <br />no numeric effluent exceedances in WY97. <br />Table 6 <br />CDPS Effluent Limitations for the WWTP (OO7A) <br />Parameter 30-Day Average 7-Day Average Daily Maximum <br />TSS (mg/L) 30 45 N/A <br />TDS (mg/L) N/A N/A Report <br />pH 6.5-9.0 6.5-9.0 6.5-9.0 <br />Oil and grease No visible sheen No visible sheen No visible sheen <br />BODY (mg/L) 30 45 N/A <br />Fecal coliform (colonies per 100 ml} 6,000 12,000 N/A <br />Total residual chlorine (mg/L) N/A N/A 0.5 <br />If visible sheen is present, grab sample results must be below 10 mg/L. <br /> <br />-0 1.450 Page rrg t ater ngrneers <br />