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MOUNTAIN COAL <br />COMPANY L. L. C. <br />West Elk Mine <br />12.0. Box 591 <br />5174 Highway 133 <br />Somerset, CO 81434 <br />(970) 929-2200 <br />Fax (970) 929-5050 <br />A Subsidiary of Arch Western Bituminous Group, LLC <br />January 15, 2011 <br />Ms. Kelly Morgan <br />Colorado Department of Public Health <br />& Environment <br />JAN 7 8 <br />Div,ision o .N <br />n'n9 n1 <br />OV <br />Water Quality Control Division <br />WQCD-P-B2 <br />4300 Cherry Creek Drive South <br />Denver, Colorado 80246-1530 <br />Re: Mountain Coal Company, LLC, West Elk Mine, CDPS Permit No. CO-0038776 <br />Discharge Monitoring Report for the 0' Quarter, 2010. <br />Dear Ms. Morgan: <br />Attached please find the Discharge Monitoring Reports (DMRs) for Mountain Coal Company, <br />LLC (MCC) West Elk Mine for the 4"' Quarter of 2010. During the 4"' quarter there were no <br />exceedances of primary limits at outfalls 004, 005, 007, 008, 009, 011, 012, 013, 014, 016, 017, <br />018 and 019. However, a series of severe rain events coupled with rapid snow melt in the month <br />of December created a need to discharge excess surface runoff from Outfall 015, which resulted <br />in an exceedance of the primary limit for TSS. As a result, MCC is exercising the alternate limits <br />per Part LA. Lb of the permit for Outfall 015 for the 4`i' quarter of 2010. The burden of proof <br />required by Part LA.2 of the permit is provided below. <br />1. Discharge from Outfall 015 occurred within 48 hours of the precipitation/snow melt <br />event. Best available data indicate that from December 18-31, 2010, excessive snow melt <br />and precipitation was observed for the majority of this two week period. The greatest 24- <br />hour rain event began on December 20th and was 1.12 inches. Discharge from Outfall <br />015 occurred on December 23, 2010 within the 48 hour window following the <br />precipitation event. <br />2. The combination of rain and snowmelt exceeded the capacity of the pond. Therefore, <br />sufficient treatment of stormwater run-off by retention and settling could not occur. <br />3. MCC's on-site rain gage data is attached; however, the December data set has been <br />invalidated because the heating coils had apparently malfunctioned and were not <br />removing ice and snow accumulations from the rain gage bucket. As such, the rain gage <br />was at times underreporting rain or not reporting at all. Nearby certified precipitation <br />data from Gunnison and Rifle show near constant precipitation during the same two week