2012-07-02_REPORT - C1980007 (3)

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West Elk Mine 2011 Annual Hydrology Report 44 ponds are designed to retain water over a period of time so settling of sediment occurs prior to discharge (batch mode). In WY 2011, ponds MB -1 and MB -2R did not discharge water to the North Fork of the Gunnison (Figure 9) (MCC, 2012). 4.3.2 Ponds MB -3, MB -4, and MB -5E Ponds MB -3, MB -4, and MB -5E receive stormwater runoff and wash -down water from the mine's conveyors, silos, and load -out facilities. In WY 2011, pond MB -4 collected a small amount of water resulting in discharges of about 0.129 ac -ft. No water was discharged from ponds MB -3 or MB -5E in WY 2011 (MCC, 2012). 4.3.3 Ponds FW -1 and FW -2 Ponds FW -1 and FW -2 store raw fresh water from the North Fork river diversion intake gallery. Water from these ponds is pumped to the mine water storage tank, the WTP and the potable water system. If the ponds overfill, excess water is discharged back to the North Fork of the Gunnison. 4.3.4 RPE Pond and NSSA Pond The RPE Pond collects stormwater runoff from the refuse pile expansion area. In WY 2011 the discharge from the RPE pond was 8.895 ac -ft (MCC, 2012). The North Soil Storage Area (NSSA) pond collects stormwater from the NSSA. In WY 2011 there was no discharge from this pond. 4.3.5 Pond SG -1 Pond SG -1 was built to collect stormwater runoff from the mine ventilation shaft bench areas. Discharge from Pond SG -1 is routed to Sylvester Gulch. In WY 2011 the discharge from pond SG -1 was 1.721 ac -ft (MCC, 2012). 4.3.6 Mine Water Treatment Polishing Ponds Underground fault water pumped from the B -seam sumps through the mine water pumping facility (MWPF) is directed to the mine water treatment ponds for aeration (if needed) and settled prior to discharge. Once treated, the water flows to Sylvester Gulch through Outfall 017. No water was discharged from this outfall in WY 2011 (MCC, 2012). June 2012 HydroGeo, Inc.