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<br />(d) Excess excavated material not necessary for diversion channel geometry or regrading of the <br />channel will be disposed of in accordance with 4.09. <br />(e) Topsoil will be handled in compliance with 4.05. <br />Sedimentation Ponds <br />In accordance with 4.05.2 and the NPDES permit, SCC will primarily use sedimentation ponds to prevent, to <br />the extent possible, additional contributions of sediment to streamflow or runoff outside the permit area due <br />to mining disturbance (see Exhibit 13-2, Surface Water Control Plan, and Exhibit 13-12.1, Yoast <br />Watershed). Please refer to Attachments 13-3, Design Report Sediment Structure Pond 010; 13-4, Design <br />Report Sediment Structure Pond 011; and, 13-12, Drainage and Sediment Control Plan, for the pond <br />designs of ponds 011A, 012, 012A, 013 and 014. <br />The sedimentation ponds and impoundments are designed, constructed, and maintained to achieve the <br />following: <br />a. Provide storage and treatment for the runoff or inflow entering the pond as a result of a 10-year, <br />24-hour precipitation event and to meet applicable State and Federal regulations for effluent <br />limitations before discharge from the permit area. <br />b. All sedimentation ponds are designed to provide adequate sediment storage volume in <br />compliance with the CDMG regulations. <br />c. An appropriate nonclogging dewatering device will be installed to dewater a 10-year, 24-hour <br />storage volume. <br />d. Appropriate combinations of principal and emergency spillways to safely discharge the runoff <br />from a 25-year, 24-hour precipitation or larger event, as required by the CDMG regulations, will <br />be installed in all ponds. <br />The sediment storage capacity of each sedimentation pond or impoundment will be monitored on an annual <br />basis to ensure that at least one year of sediment storage is available beneath the principal spillway inlet <br />(based on R.U.S.L.E.). When adequate capacity is no longer available, sediment removal or other <br />corrective actions will be taken to restore adequate sediment storage capacity to the pond. <br />SCC will monitor the sediment storage capacity of each pond with one or a combination of the following <br />methods, as applicable: <br />1. Reference Stake - A reference stake will be set at a predetermined clean-out elevation beneath <br />the principal spillway. When sediment storage reaches this elevation, corrective action would <br />i <br />TR-37 ~ 4 Revised 02/08 <br />