2008-06-27_REPORT - C1980007 (4)

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West Elk Mine 2007 Annual Hydrology Report 39 • 4.4.1 Ponds MB-1 and MB-2R Pond MB-1 collects the Project's surface operations water and diverts storm water runoff. Water from Pond MB-1 can be discharged into either the North Fork of the Gunnison River or Pond FW- 1. Pond M13-2R receives water from surface operations, storm runoff, and effluent from the WWTP. Discharge from MB-2R is typically routed to the North Fork, but can be diverted to Pond FW-1, if necessary. Both Pond MB-1 and Pond MB-2R retain water, so settling of sediment occurs prior to discharge (batch mode). In WY 2007, Pond MB-1 discharged 103.6 ac-ft and MB-2R discharged 95 ac-ft of water to the North Fork (Figure 8)(MCC, 2008). There were no CDPS Permit exceedances for the discharge water quality from these ponds in WY 2007 (MCC, 2008). 4.4.2 Ponds MB-3, MB-4, and MB-5 Ponds MB-3 and M13-4 receive storm water runoff and wash down water from the Project conveyors, silos, and load out facilities. Pond MB-5 collects only storm water runoff. In WY 2007 pond MB-3 and MB-4 collected a small amount of water resulting in discharges of about 2.3 ac-ft. Water was not discharged from pond MB-5 in WY 2007 (MCC, 2008). is 4.4.3 Pond FW-1 Pond FW-1 is designed to store raw fresh water from the North Fork diversion intake gallery. Pond FW-1 water is pumped to the WWTP and the Project's domestic water system. If the pond overfills, excess water is discharged back to the North Fork. Water was not discharged from pond FW-1 in WY 2007 (MCC, 2008). 4.4.4 RPE Pond The RPE Pond collects runoff from the refuse pile expansion area. In WY 2007 no discharge occurred from the RPE pond (MCC, 2008). 4.4.5 Pond SG-1 Pond SG-1 was built to collect runoff during and after construction of the mine ventilation shafts. Discharge from Pond SG-1 is routed to Sylvester Gulch. In WY 2007, no discharge occurred from Pond SG-1 (MCC, 2008). • June 2008 HydroGeo, Inc.