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Mountain Coal Company Exhibit 69 <br /> West Elk Mine Sylvester Gulch Facilities <br /> • During batch flow operation, mine water will be pumped into the first pond(existing Pond 017) <br /> at 400 gpm with the mine pump turned off when the pond water surface reaches El. 6825.0 ft <br /> MSL. Flow from Pond 017 to the Second Pond will be via a 12-inch diameter pipe at an inlet <br /> invert elevation of 6820.0 ft MSL. The volume of the existing pond between El. 6820 and 6825 <br /> ft MSL is approximately 230,000 gallons. Therefore, inflow at 400 gpm can occur for <br /> approximately 9.6 hours during which time aeration will continue. Flow through the pipe will be <br /> controlled with a full-port motor controlled-valve connected to a time switch, which will open <br /> the valve 6 to 15 hours after the pond water surface reaches El. 6825.0 ft MSL and the mine <br /> pump is turned off. Thus, under this scenario,the total aeration time would be at least 15 to 24 <br /> hours prior to discharge to the Second Pond. The aeration time requirements will likely vary <br /> depending upon the iron concentrations in the influent, and the controls can be adjusted by the <br /> pond operator to allow more or less aeration time. The automatically-controlled valve will be <br /> placed in a 48-inch diameter manhole for maintenance access as necessary. <br /> An emergency overflow spillway will also be installed in the first pond(Pond 017)with an inlet <br /> invert El. 6825.5 ft MSL,with outfall to 'he Second Pond,to prevent direct discharge from Pond <br /> 017 into Sylvester Gulch. This will provide flow from Pond 017 to the Second Pond in the event <br /> that the mine water pump continues beyond its normal cycle time or the valve between Pond 017 <br /> and the Second Pond malfunctions. <br /> The Second Pond will have an operating capacity of approximately 1.2 million gallons (3.7 acre <br /> • feet). This will provide a detention time in excess of 48 hours at the design flow rate of 400 gpm <br /> assuming a maximum sediment depth of 2 feet. The pond invert(top of liner)will be <br /> approximately El. 6804. ft MSL at the south and north ends, increasing to El. 6805.0 ft MSL in <br /> the middle of the pond where a geoimeimbrane baffle will be located. This will provide for <br /> sediment accumulation at the north and south ends of the pond. A geomembrane baffle, with a <br /> flow-through window, will divide the pond into two cells at the approximate mid-point to <br /> prevent short-circuiting through the pond. The normal operating water surface will be El. 6818.0 <br /> ft MSL. Both ponds will accommodate the precipitation from a 10-year, 24-hour storm event. <br /> Because neither pond receives drainage from adjacent areas, this storm event would raise pond <br /> water surfaces a maximum of only 0.2 feet. <br /> Following detention and sedimentation in the Second Pond, normal discharge from the Second <br /> Pond will be via gravity flow from a 12-inch diameter overflow pipe located at the northwest <br /> coiner of the pond with an inlet invert elevation of 6817.4 ft MSL. A low-level 12-inch diameter <br /> pipe having an invert elevation of 6806.0 ft MSL will be located near the overflow pipe at the <br /> northwest corner of the pond. A mid-level discharge pipe will also be installed to increase <br /> operational flexibility. These pipes will have valves in a 48-inch diameter manhole that will <br /> normally be.closed. <br /> Flow from either the overflow pipe, mid-level pipe or low-level pipe will proceed to a weir and <br /> gate structure on the northwest bank of the Second Pond. This structure will contain a V-notch <br /> weir with a pressure transducer and data logger to record the discharge flow rate. A lower-level <br /> • gate will be installed in the weir wall to provide pond drawdown when necessary. This lower- <br /> 6 <br /> Rev.10197-TR83,Rev.04109-TR116 <br /> i <br />