2010-02-24_REVISION - C1996083 (3)

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• 2.05.3 from the inflow from any underground mine. The calculations presented in Volume 111, 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. Sediment pond F collects run -off from the new gob disposal area. Pond F is a typical sediment pond, capable of containing the run -off from a 10 -year event with an emergency spillway system designed to handle the peak flow generated by the 25 -year storm event. The initial sections of the emergency spillway are riprap plated open channels. Flow is conveyed over the fire Mountain Canal in a metal flume. Dewatering of Pond F will be by pumping through a buried 4 -inch diameter primary spillway pipe that discharges into D -Gulch where the flow goes under SH -1336, over the Deer Trail Ditch and under the Fire Mountain Canal. C7 PR -12 2.05-38- 02/10