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~~MOUN~fdIN COAL ~COMPdNYf_.~.~. A Subsidiary of Arch Western Resources, LLC January 3I, 2007 West Ells Mine /'~ `,C POBox 591 ~~L~~ V CD 5174 Highway 133 ' r ~ Somerset, CO 81434 F E~ ~ 2 Z~~~ (970) 929-5015 L Fax (970) 929-5595 pjU iti.,~~, pf Raclamation, fNuwty and Safety Ms. Cazla J. Lenkey Colorado Department of Public Health and the Environment Water Quality Control Division (WQCD), Enforcement and Compliance Section 4300 Cherry Creek Drive South Denver, CO 80222-1530 Re: Mountain Coal Company, LLC (MCC), West Elk Mine, CDPS Permit No. CO-0038776, Discharge Monitoring Reports for the Fourth Quarter 2006. Dear Ms. Lenkey: Attached are the Dischazge Monitoring Reports (DMRs) for the fourth quarter of 2006 Also attached are the Biomonitoring reports from Enviro-Chem Laboratories, October, 2006, for Outfa11017. The dischazge from Outfa11017, passed the biomonitoring tests in Daphnia magna populations and the fathead minnow, Pimephales promelas, populations were unaffected. One excursion was noted for the W WTP in November, (outfa11007A) for BOD 5-day, 7-day Maximum Average. The result was 60.6 mg/L BOD 5-day and the maximum is 45 mg/L for the 7-day average. This outfall (007) has an approximate flow of 6500 gallons per day that flows to MB-2R (outfall 004) via ashotcrete-lined ditch for approximately 1,000 feet. The pond at MB-2R has a surface area of 2 acres and a designed detention volume of 14.71 acre-feet. Given the small W WTP flow of 4.5 to 10 gallons per minute, and the large assimilative capacity of MB-2R pond, MCC can assure the Division that the excursion is ameliorated by the oxygenation of the W WTP flow in combination with the riffle distance of the shotcrete-lined ditch, detention time and surface area of the MB-2R pond. In the future, MCC will be requesting the lab provide MCC with analyses in a timely manner so that additional sampling can be achieved if there is an excursion from the water quality compliance parameters.