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Mountain Coal Company, LLC <br />Exhibit 67 <br />West Elk Mine Windy Gap Process <br />Pond Evaporation <br />An estimate of 45-inches per year for Class A pan evaporation was obtained from <br />USWB TP 37, 1959. A pan coefficient of 0.75 was used to obtain an annual pond <br />evaporation estimate of 33.8 inches per year. Since all precipitation reaching the <br />ponds would be available for release or evaporation, the net evaporation is 13.7 <br />inches per year (using a typical annual precipitation of 20.1 inches). <br />Consequently, for a total pond surface area (as below) of 5.4 acres, the maximum <br />annual evaporation loss is 6.2 acre-feet. The maximum surface areas of the <br />ponds (conservatively assuming all are full year-round) are as follows: <br />FW-1 0.9 ac. <br />FW-2 1.0 ac. <br />MB-3 0.2 ac. <br />MB-4 0.1 ac. <br />MB-5E 2.2 ac. <br />SG-1 0.5 ac. <br />RPE Pond 0.5 ac. <br />Coal Preparation Plant <br />WEM's Coal Preparation Plant will be a net user of raw water at a rate of <br />approximately 4.46 gallons per ton of raw coal fed through the plant. Very <br />conservatively assuming that 50% of the WEM raw coal will be washed, at <br />maximum production levels, approximately 4.1 million tons will be processed <br />annually through the plant resulting in a net consumption of 56.0 acre-feet of <br />water per year. <br />Miscellaneous Water Use <br />Miscellaneous water use includes surface road dust suppression, potable water, <br />and equipment/facilities wash-down water. It should be noted that much of the <br />usage associated with the above activities has return flows via WEM's WWTP <br />and the sedimentation ponds. Using data from 2007 and 2008, the average <br />amount of potable water treated was calculated to be 14.0 acre-feet. Also, WEM <br />estimates other miscellaneous water use (drilling water, etc.) to be an additional <br />5.0 acre-feet. Therefore, the total miscellaneous water use is approximately 19.0 <br />acre-feet per year. <br />Return Flows <br />Return flows to the North Fork are attributed to discharges of treated effluent from <br />WEM's WWTP, mine site dust suppression and wash-down runoff that is collected in the <br />sediment ponds, raw water imported and circulated through the mine, as well as mine <br />water inflows that are captured and then discharged from the mine. Utilizing data from <br />Exhibit 67-2 Revised 03105- PRII; 01106- PRII; 03106- PRII; 09109- TR118; 09109- TR119