2014-07-11_REPORT - C1980007 - Laserfiche WebLink

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West Elk Mine 2013 Annual Hydrology Report 44 4.5.2 Sanitary Wastewater MCC maintains an activated sludge wastewater treatment plant (WWTP) to handle sanitary wastewater generated by the West Elk Mine. The WWTP has been in continuous operation since 1982 and was enlarged in WY 1997 to handle up to 20,000 gallons per day. As shown on Figure 9, the WWTP (007) discharges into pond MB -5E where the effluent mixes with stormwater runoff stored in the pond, prior to discharge to the NFGR. Both discharges from the WWTP and pond MB -5E are monitored by MCC, as required by the CDPS permit. 4.5.3 Sedimentation Ponds The sedimentation and treatment ponds (Figure 9) at the mine site are utilized to manage mine water, stormwater runoff, and wastewater treatment effluent. In WY 2013, pond SG -1 discharged 3.2 ac -ft into the NFGR via Sylvester Gulch. There was no discharge from ponds MB -3, MB -4, the RPE pond, the MB -5E pond or the NSSA pond in WY 2013 (Figure 9) (MCC, 2014). Table 11 summarizes the CDPS discharge permit parameters and limits for the sedimentation ponds. Table 11. Summary of CDPS Discharge Permit Limits for Sedimentation Ponds' Parameter and Time Period Sedimentation Pond Discharge Limits TSS (mg/L) • 30 -Day Average 35 • Daily Maximum 70 Oil and Grease (mg /L) • Daily Maximum No Sheen or 10 Total Iron (µg/L) • 30 -Day Average 3,500 • Daily Maximum 7,000 H (s.u.; minimum — maximum) 6.5 -9.0 Settleable Solids (ml /L) Daily Maximum 0.5 (1) CDPS Permit No. CO- 0038776 (CDPHE, 2009a and b). 4.6 Permit Compliance MCC operations were generally in compliance with Permit CO- 0038776 limitations in WY 2013 and only had one exceedance (MCC, 2014). The WY 2013 discharge data for the regulated parameters for outfalls 004, 005, 007, 008, 009, 011, 012, 013, 014, 015, 016, 017, 018 and 019 are summarized in Table 12. June 2014 HydroGeo, Inc.