2011-08-01_REPORT - C1980007 (5)

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• 1.0 INTRODUCTION Mountain Coal Company, LLC's (MCC) West Elk Mine 2010 Annual Hydrology Report (AHR) describes details of the hydrologic monitoring activities and summarizes pertinent data with respect to mining operations as required by MCC's Permit C- 1980 -007 with the Colorado Division of Reclamation, Mining and Safety (CDRMS) for the Water Year 2010 (WY 2010), October 1, 2009 through September 30, 2010. • West Elk Mine 2010 Annual Hydrology Report 1 1.1 Overview of Mining Operations The West Elk Mine is an underground coal mining operation that produces bituminous coal and conducts other mining activities including surface crushing, washing, conveying and load -out operations. MCC has utilized two chemicals in their treatment process: aluminum sulfate for flocculation in sedimentation ponds and sodium hypochlorite for drinking water treatment. During WY 2010, mining was completed in E -seam longwall panels El and up to crosscut 42 in panel E2. Development mining was completed in the gateroads for longwall panels E2, E3, and E4, as well as the E -South Mains, and the E4 recovery chute (Map 1B). There was no mining in the B -seam in WY 2010 (Map 1A). 2.0 HYDROLOGIC SUMMARY OF WATER YEAR 2010 During WY 2010, October 1, 2009 through September 30, 2010, the total annual precipitation in the vicinity of the West Elk Mine was below average at the Paonia 1 SW (56306) and McClure Pass (59743/CO07K09S) meteorological and Snotel stations, and above average at Overland Reservoir (59853/CO07K14S) Snotel station compared to historical (30 -year) total annual precipitation data (CCC, 2011; NRCS, 201la; NRCS 2011b; WRCC, 2011). During WY 2010, the snow water equivalent (SWE) data were slightly below the historical annual averages at Overland Reservoir and McClure Pass stations (NRCS SNOTEL, 2010c), resulting in below to near average stream flows in the permit and surrounding areas (Figures 1 -5). July 2011 HydroGeo, Inc.