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(d) Excess excavated material not necessary for diversion channel geometry or <br />regrading of the channel will be disposed of in accordance with 4.09. <br />(e) Topsoil will be handled in compliance with 4.06. <br />Sedimentation Pond 007 <br />Other ponds are discussed in the Attachment 2.05.3(3)-10. In accordance with 4.05.2 and the <br />approved NPDES permit, WFC will use Pond 007 to prevent, to the extent possible, additional <br />contributions of sediment to stream flow or runoff outside the permit area due to mining disturbance <br />(see Exhibit 2.05.3-1). Attachment 2.05.3(3)-1 gives the design calculations on Sediment Pond <br />007. Attachment 2.05.3-6 gives the typical soil grain size distribution information. Exhibit 2.05.3-5 <br />and Exhibit 2.05.3-6 shows the design of Pond 007. <br />The sedimentation pond is designed, constructed, and maintained to: <br />a. Provide storage for the runoff or inflow entering the pond as a result of a 10-year, <br />24-hour precipitation event and to meet all applicable State and Federal regulations <br />for all effluent limitations before discharge from the permit area. The characteristics <br />of the mine site, reclamation procedures, and on site sediment control practices are <br />also considered in the design. <br />b. The sedimentation pond was designed to provide adequate sediment storage <br />volume in compliance with the CDMG regulations. <br />c. An appropriate nonclogging dewatering device will be installed to maintain a 10- <br />year, 24-hour storage volume. <br />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 monitored on an annual basis 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 longer available, sediment removal <br />or other corrective actions will be taken to restore adequate sediment storage capacity to the pond. <br />• <br />tREVISED 72100) 2.05.3(3) - 4 <br />