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West Elk Mine 2007 Annual Hydrology Report 38 <br />• 4.4 Sedimentation Ponds <br />There are 7 sedimentation ponds (Map 2 and Figure 8) at the Project that are utilized to manage <br />mine water, storm water runoff, and wastewater treatment effluent. All of the ponds except MB-5 <br />and M13-3 have been re lined to prevent seepage. There is also a "freshwater" pond (FW-1) that is <br />used to equalize diversions from the North Fork of the Gunnison River and provide storage. Pond <br />FW-1 serves as the raw fresh water supply for the mine's domestic water use and in-mine water <br />needs. <br />In WY 2007, four ponds discharged water to the North Fork, ponds, MB-1 (103.6 ac-ft), MB-2R <br />(95.0 ac-ft), MB-3 and 4 (2.3 ac-ft), and SG-1 (1 ac-ft) as illustrated on Figure 8 (MCC, 2008). <br />Ponds MB-5 and the RPE pond had no discharge in WY 2007 (MCC, 2008). Table 10 summarizes <br />the water quality data of all CDPS discharges for WY 2007. Table 11 shows the CDPS discharge <br />permit parameters and limits for the sedimentation ponds. <br /> <br />• <br />Table 11 <br />Summary of Sedimentation Pond CDPS Discharge Permit Limits <br />Parameter and Time Period Sedimentation Pond <br /> Discharge Limits <br />TSS (mg/1) <br />• 30-Day Average 35 <br />• 7-day average n.a. <br />• Maximum 70 <br />TDS (mg/1) <br />• 30-Day Average n.a. <br />• 7-day average n.a. <br />• Maximum Report <br />Oil and Grease (1) <br />• 30-Day Average No Sheen <br />• 7-day average No Sheen <br />• Maximum No Sheen <br />Total Iron (mg/1) <br />• 30-Day Average 3.5 <br />• 7-day average n.a. <br />• Maximum 7.0 <br />pH (S.U.) <br />• 30-Day Average 6.5-9.0 <br />• 7-day average 6.5-9.0. <br />• Maximum 6.5-9.0 <br />1) No Sheen or less than 10 mg/l <br />June 2008 HydroGeo, Inc.