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• d. Appropriate combinations of principal and emergency spillways to safely discharge <br />the runoff from a 25-year, 24-hour precipitation or larger event, as required by the <br />CDMG's regulations, will be installed. <br />The sediment storage capacity of the sedimentation pond will be periodically monitored to <br />ensure that at least one year of sediment storage is available beneath the principal spillway inlet <br />(based on the U.S.L.E. or the equivalent sediment storage of one 10-year, 24-hour storm event <br />based on the M.U.S.L.E.). When adequate capacity is no longeravailable, sediment removal <br />or other corrective actions will be taken to restore adequate sediment storage capacity to the <br />pond. <br />Corrective action required to restore adequate sediment storage capacity may include the <br />following: <br />1. Raise the spillway and redesign the pond in order to restore adequate storage <br />capacity and to comply with the applicable regulations. <br />2. Excavate the pond area and enlarge the sediment storage capacity. <br />• The excavated material suitable for topsoil will be salvaged in a stockpile used for reclamation. <br />The excavated material that is not suitable for atopsoil-like medium will be graded into the <br />surrounding topography within the disturbance area, topsoiled, and revegetated in accordance <br />with W FC's approved reclamation plan. Site specific conditions will determine the construction <br />methods and equipment utilized at the time of excavation. Sediment removal and water <br />discharges will be conducted consistent with the approved mining permit, the NPDES permit, <br />and CDMG Regulations Section 4.05.6(3)(b). All sedimentation ponds will be inspected <br />quarterly under the supervision of a registered professional engineer and reported to the CDMG. <br />The revised NPDES Permit is enclosed in Attachment 2.05.3(3)-18. <br />Pit dewatering will be primarily a seasonal occurrence. The dewatering process will be a <br />sporadic, operation-controlled occurrence depending on various factors which may include the <br />location of the pit inflows, the location of standing water in the pit, or the location within the pit <br />of the overburden and coal removal operations. When pit dewatering is required, the anticipated <br />dewatering rate will be in the range of one to two cubic feet per second or less. Direct pit <br />pumping into Pond 007 is planned for the mining east of 2700 Road. Once mining continues <br />west of 2700 Road, Pond 011 will be used to detain the pit pumping prior to discharge. At that <br />• time, Pond 007 will be somewhat over designed. These procedures have been approved in <br />(Revised July 2006) 2.05.3(3)-11 <br />