Laserfiche WebLink
<br /> <br />West Elk Mine 2003 Annual Hydrology Report <br />5.1.2 North Fork of the Gunnison <br />MCC discharges to the North Fork via sediment ponds (MB-2R and MB-4) and direct discharges to <br />Sylvester Gulch (discharge points 017A and 018a). The major cations and anions of the pond <br />discharge water are sodium and bicarbonate. The sediment pond discharge water is slightly <br />alkaline with a pH ranging from 6.50 to 8.99, with TDS concentration ranging from 153 mg/1 to <br />380 mg/1. The major cations and anions of the MWPF discharge water are sodium and <br />bicarbonate. The Sylvester Gulch discharge water is slightly alkaline with a pH ranging from 8.00 <br />to 8.42, with TDS concentration ranging from 2,482 mg/1 to 2,900 mg/1. <br />A salinity (TDS) loading analysis of the MCC's WY2003 discharges was completed relative to the <br />current North Fork Cumulative Hydrologic Impacts Analysis (CHIS) (CDMG, 2003). The CHIS <br />analysis was conducted to assess the potential cumulative hydrologic impacts of mining and other <br />activities in the North Fork Valley on the North Fork's water quality and flow. The CHIS analysis <br />determined that no significant hydrologic impacts were expected as a result of mining activities. <br />The CHIS assumed that MCC's contribution to the North Fork would be 5,520 gpm with a TDS <br />concentration of 2,500 mg/1. The total WY2003 discharge from the Project was approximately 399 <br />gpm from CDPS gpm. The flow weighted maximum annual salinity (TDS) load from the Project <br />was 1567 tons. This is about 5 percent of the value used in the CHIS. A summary of the salinity <br />loading from the mine compared to the CHIS study is shown on Table 11. <br />Table 11 <br />Summary of Salinity Loading in the North Fork <br /> Average Maximum Flow Calculated <br />Scenario Continuous Weighted TDS Annual Salinity Percent of <br /> Discharge Rate Concentration Loading CHIS Loading <br /> m m tons/ ear <br />WY2003 399 1747 1567 5% <br />2003 CHIS t't 5520 2500 30,159 - - <br />(1) Based on maximum permitted discharge rate <br />5.2 Springs and Seeps <br />C~ <br />MCC routinely monitors 24 springs and seeps, listed in Table 3. Spring hydrographs are presented <br />in Appendix D, and flow and water quality data are in Appendix E. <br />5.2.1 Water Quantity and Quality <br />Spring and seep flows in WY2003 continued to be below normal due to several years of below <br />normal snow pack and precipitation however more springs were wet or flowing in WY2003 than in <br />September 2004 <br />31 <br />HydroGeo, Inc. <br />