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Vest Elk Mine 2004 Annual Hydrology Report 29 • 4.3 Sedimentation Ponds There are 7 sediment ponds (Map 2 and Figure 3) at the Project that are utilized [o manage mine water, storm water runoff, and wastewater treatment effluent. All of the ponds except MB-5 and MB-3 aze re lined to prevent seepage. There is also a "freshwater" pond (FW-1) that is used to equalize diversions from the North Fork and provide storage. Pond FW-1 serves as the raw fresh water supply for the mine's domestic water use and in-mine water needs. In WY2004, three ponds discharged water to the North Fork, ponds, MB-1 (8.0 ac-ft), MB-2R (74.0 ac-ft), and MB-4 (1.0 ac-ft). Ponds MB-3, MB-5, RPE, FW-1, and SG-1, had no discharge in WY 2004. Table 9 summarizes the water quality of all CDPS discharges, including sedimentation pond (SG-1), for WY 2004. Table 10 shows the CPDS discharge permit limitation values for the sediment ponds. Figure 3 illustrates the mine water balance including the pond discharges. Table 10 Summary of Sediment Pond CDPS Discharge Permit Limits • Parameter and Time Period Sedimentation Pond Discharge Limits TSS (mgN 30-Day Average 35 7-day average n.a. • Maximum 70 TDS (mgA) • 30-Day Average n.a. 7-day average n.a. Maximum Report Oil and Grease (1) • 30-Day Average No Sheen 7-day average No Sheen Maximum No Sheen Total Iron (mgA) 30-Day Average 3.5 • 7-day average n.a. • Maximum ~•0 pH (S.U.} • 30-Day Average 6.5-9.0 7-day average 6.5-9.0. • Maximum 6.5-9.0 (1) No Sheen or less than 10 mp~l 4.3.1 Ponds MB-I and MB-2R Pond MB-1 collects the Project's surface operations water and diverted storm water runoff. Water from Pond MB-1 can be discharged into either the North Fork or Pond FW-1. Pond MB-2R • receives surface operations water, 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 August zoos HydroGeo, Inc.