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Mountain Coal Comparry 1998 Auuual Hydrology Report West EIk 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 tight. Approximately 372 acre-feet of water were diverted using this <br />water right during WY98. <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 eazly fall. In WY98, a call was placed on the North Fork <br />from August 4 through September 30. Out-of-priority diversions were augmented using releases <br />from East Beckwith Reservoir (a.k.a. Lost Lake Slough). Due largely to the fault inflows, MCC <br />was a net contributor of approximately 255 acre-feet of water to the North Fork during WY98. <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 WY97 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 dischazges into pond MB-2R, 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 pazameters that apply to the WWTP aze shown in Table 6. The <br />dischazge designation for the WWTP is 007A, and the dischazge designation for pond MB-2R is <br />004A. <br />As shown for the WWTP (007A) on Table 8, the maximum concentrations during WY98 for all <br />regulated parameters were less than the corresponding CDPS limitations (Table 7). There were <br />no numeric effluent exceedances in WY98. <br />Table 7 <br />CDPS Effluent Limitations for the WWTP (007A) <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 />BODS (mg/L) 30 45 N/A <br />Fecal coliform (colonies per 100 ml) 6,000 12,000 N/A <br />Total residual chlorine (mgJL) N/A N/A 0.5 <br />• <br />83l - 32.500 age 1 rig t Water Engineers <br />