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Mountain Coal Compan~~ 2000 Annual Hydrology Report WesrElk 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 705 acre-feet of water were diverted using this <br />water right during Vl'Y00. The diversions were significantly higher than normal due to water <br />needed to control the thermal event. <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. In WY00, a call was placed on the North Fork <br />from July 6, 2000 until the end of the water year. Out-of-priority diversions aze augmented using <br />releases from East Beckwith Reservoir (a.k.a. Lost Lake Slough). <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 WWTP has been operating since 1982 and <br />was enlarged in Vb'Y97 to handle up to 20,000 gallons per day. Discharges are made in <br />accordance with CDPS Permit No. CO-0038776. <br />As shown on Figure 6, the WWTP discharges into pond MB-2R, where the effluent mixes with <br />stormwater runoff and surface operations mine water stored in the pond, prior to discharge to the <br />• North Fork. Both discharges from the WWTP and pond MB-2R must be monitored by MCC as <br />required by the CUPS permit. The regulated parameters that apply to the WWTP are shown in <br />Table 6. The discharge designation for the WWTP is 007A, and the discharge designation for <br />pond MB-2R is 004A. <br />As shown for the WWTP (007A) on Table 8, the maximum concentrations during WY00 for al] <br />regulated parameters were less than the corresponding CDPS limitations (Table 7). There were <br />no numeric effluent exceedances in WY00. <br />Table 7 <br />CDPS Effluent Limitations for the WWTP (007A) <br />Parameter 30-Dav Avera a 7-Da Avera a Dail Maximum <br />TSS(m /L) 30 45 N/A <br />TDS (m /L) N/A N/A Re ort <br />H 6.5-9.0 6.5-9.0 6.5-9.0 <br />Oil and crease No visible sheen No visible sheen No visible sheen <br />BOD. (me/L) 30 45 N/A <br />Fecal colifotm (colonies er 100 ml) 6,000 12,000 N/A <br />Total residual chlorine (mg/L) N/A N/A 0.5 <br />• <br />83/-03?.550 Page 14 Wright lVarerEngineerc <br />