2010-04-16_PERMIT FILE - C1996083A (9)

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• 2.05.3 (4) Ponds, Impoundments and Diversions (a) There will be three sediment ponds constructed for the mine facilities. The ponds are named sediment ponds B, C and D. Sediment pond D will also be referred to as the refuse pile sediment pond. The loadout will have two sediment ponds. The ponds are named sediment ponds J and K. Sediment pond A was deleted from the design. Sediment pond B was relocated below (south of) old State Highway 133 during the construction of the downhill conveyor and highway coal stockpile. It is designed to handle the run -off from B- Gulch. Pond B will be a typical sediment pond, capable of containing the run -off from a 10 -year event with a spillway system designed to handle the peak flow generated by the 25 -year storm event. Dewatering will be through the primary spillway or an optional centrifugal pump. Sediment pond C is located above (north of) the old Bowie railroad grade and is designed to handle the run-off from C- Gulch. Sediment pond C also receives inflow from the mine. A small water treatment building located northwest of Pond C is used to add CDPS approved chemicals to the water as necessary to clarify the water. A sediment pond is to provide adequate capacity to contain or treat the run -off or inflow entering the pond as a result of a 10 -year, 24 -hour precipitation event and any additional storage resulting from the inflow from any underground mine. The calculations presented in Volume III, Exhibit 8, pages 7 and 8, show Pond C has adequate capacity to contain inflow from the mine and the 10 -year, 24 -hour precipitation event. Pond C has and emergency spillway system designed to handle the peak flow generated by the 25 -year storm event. Sediment pond D is the refuse pile sediment pond (also referred to as Pond D). It is designed to handle the run -off from the entire refuse pile area #1, and part of the runoff from refuse pile area #4. See Volume III, Exhibit 8 for details of this sediment pond and associated ditches. Sediment pond J is located south of the tracks below topsoil stockpile F. There is a berm /upper diversion ditch designed to divert upland drainage away from the topsoil stockpile. Pond J is a typical sediment pond, capable of containing the run -off from a 10 -year event with a spillway system designed to handle the peak flow generated by the 25 -year storm event. Dewatering of Pond J will be by pumping. Sediment pond K collects run -off from the batch weigh loadout and surrounding area. Pond K is a typical sediment pond, capable of containing the run -off from a 10- year event with a spillway system designed to handle the peak flow generated by the 25 -year storm event. 2.05-29- 09/09 7R-6 9 A PPAou'r-D / 22/2-9/0 9