Laserfiche WebLink
(d) Excess excavated material not necessary for diversion channel geometry or re -grading of the <br />channel will be disposed of in accordance with 4.09. <br />(e) Topsoil will be handled in compliance with 4.06. <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 to <br />mining disturbance (see Exhibit 13-2, Surface Water Control Plan, and Exhibit 13-12.1, Yoast Watershed). <br />Please refer to Attachments 13-3, Design Report Sediment Structure Pond 010; 13-4, Design Report Sediment <br />Structure Pond 011; and, 13-12, Drainage and Sediment Control Plan, for the pond designs of ponds 011A, <br />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 compliance <br />with the CDMG regulations. <br />C. An appropriate non -clogging 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 from a <br />25 -year, 24-hour precipitation or larger event, as required by the CDMG regulations, will be installed <br />in all ponds. <br />The sediment storage capacity of each sedimentation pond or impoundment will be monitored by visual <br />inspection on an annual basis to ensure that at least one year of sediment storage is available beneath the <br />principal spillway inlet (based on R.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 />During normal water years sediment ponds 011, 011A, 012A, 013, and 014 generally have stop flowing mid- <br />summer. Seneca Property, LLC (SPL) request a variance from the requirement to conduct annual surveys of <br />these sediment ponds. In return, SPL will conduct visual inspection of the sediment ponds once the water <br />levels have dropped and the inlets are visible. If SPL notes sufficient sediment build-up and storage capacity is <br />hindered, <br />MR -47 4 Revised 12/16 <br />