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Mountain Coal Company Exhibit 69 <br /> West Elk Mine Sylvester Gulch Facilities <br /> • concentration of the mine water in the first pond (existing Pond 017), followed by sedimentation <br /> in a new, Second Pond. The existing Pond 017 will be modified to function as the aeration cell. <br /> After aeration and settling, discharge from the Second Pond will be routed through a new <br /> pipeline that will connect to the existing outlet pipe and flow to the existing outfall structure <br /> along the West Fork of Sylvester Gulch. <br /> A design flow rate of 400 gallons per minute(gpm) is assumed, which will be achieved by <br /> installing a new lower-capacity pump system in the mine water sump. This will facilitate the <br /> need to provide 300 gpm continuous flow of augmentation water at certain times of the year <br /> (principally July and August),while allowing for some increased detention time if needed for <br /> treatment efficiency. <br /> From the Dewatering Pump Station Building, the mine water will flow by gravity through the <br /> existing 12-inch diameter pipeline to the existing Pond 017 inlet. Pond 017 is an HDPE-lined <br /> pond with no inputs other than mine water. Access to the pond is controlled by 6-foot high chain <br /> link fence topped with three-strands of barbed wire. <br /> The existing outlet pipe from Pond 017 is a 12-inch fused HDPE pipe installed on the ground <br /> surface with two concrete anchor blocks. At the West Fork of Sylvester Gulch, the pipe <br /> discharges approximately 2 feet above the creek high flow line and is protected by 12-inch <br /> riprap. Additional erosion protection is provided in an outlet structure by use of an energy <br /> • dissipater. Designs for the outlet pipe and structure are provided in Exhibit 66. <br /> Dewatering Pump Station Building <br /> The Dewatering Pump Station Building will contain both the mine pumping equipment and the <br /> electronic controls for water flow. In the past, dewatering has occurred intermittently from one <br /> of two existing dewatering boreholes via a vertical turbine pump with a capacity of 2,000 gallons <br /> per minute (gpm). The new pump system design flow is 400 gpm. The dewatering boreholes <br /> have a column depth of approximately 600 feet and are completed to the operational sump in the <br /> northeast corner of the 1 ONE Tailgate. <br /> The existing system is equipped to use a nearby Recirculation Borehole to reduce/regulate the <br /> flow rate by recirculating a portion of the flow through the mine sump. The recirculation <br /> borehole is a 12-inch cased borehole(completed per MR 212)that is located approximately 100 <br /> feet south of the dewatering boreholes. There are two 20-inch cased boreholes (also completed <br /> per MR 212) that serve as alternate recirculation boreholes and/or boreholes for water level <br /> indicators. These holes are located near the dewatering boreholes. Continued use of this <br /> recirculation system is not anticipated given the new lower flow rate pump,but the system will <br /> remain in place in case it is needed in the future. <br /> Modifications to Existing Pond 017 <br /> • <br /> 3 <br /> Rev. 10/97-TR83,Rev.04109-TR116 <br />