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2.05.3 <br />(4) Ponds, Impoundments and Diversions <br />(a) There will be three sediment ponds constructed for the mine facilities. The ponds <br />are named sediment ponds B, C and D. Sediment pond D will also be referred to as <br />the refuse pile sediment pond. The loadout will have two sediment ponds. The <br />ponds are named sediment ponds J and K. <br />Sediment pond A was deleted from the design. <br />Sediment pond B was relocated below (south of) old State Highway 133 during the <br />construction of the downhill conveyor and highway coal stockpile. It is designed to <br />handle the run-off from B-Gulch. Pond B will be a typical sediment pond, capable of <br />containing the run-off from a 10-year event with a spillway system designed to <br />handle the peak flow generated by the 25-year storm event. Dewatering will be <br />through the primary spillway or an optional centrifugal pump. <br />Sediment pond C is located above (north of) the old Bowie railroad grade and is <br />designed to handle the run-off from C-Gulch. Sediment pond C also receives inflow <br />from the mine. A small water treatment building located northwest of Pond C is used <br />to add CDPS approved chemicals to the water as necessary to clarify the water. A <br />• sediment pond is to provide adequate capacity to contain or treat the run-off or inflow <br />entering the pond as a result of a 10-year, 24-hour precipitation event and any <br />additional storage resulting from the inflow from any underground mine. The <br />calculations presented in Volume III, Exhibit 8, pages 7 and 8, show Pond C has <br />adequate capacity to contain inflow from the mine and the 10-year, 24-hour <br />precipitation event. Pond C has and emergency spillway system designed to handle <br />the peak flow generated by the 25-year storm event. <br />Sediment pond D is the refuse pile sediment pond. It is designed to handle the run- <br />off from the entire refuse pile area. There is an upper diversion ditch designed to <br />divert run-off away from the top of the refuse pile. See Volume 4, Coal Mine Waste <br />Bank Final Design for details of this sediment pond and upper diversion ditch. <br />Sediment pond J is located south of the tracks below topsoil stockpile F. There is a <br />berm/upperdiversiondltch designed to divert upland drainage away from the topsoil <br />stockpile. Pond J is a typical sediment pond, capable of containing the run-off from <br />a 10-year event with a spillway system designed to handle the peak flow generated <br />by the 25-year storm event. Dewatering of Pond J will be by pumping. <br />Sediment pond K collects run-off from the batch weigh loadout and surrounding <br />area. Pond K is a typical sediment pond, capable of containing the run-offfrom a 10- <br />yearevent with a spillway system designed to handle the peak flow generated by the <br />. 25-year storm event. <br />TR-47 <br />2.05 - 29 - 03/07 <br />RPPRovsD <br />-7 ~ 1707 <br />