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D. Sedimentation Ponds <br /> Information on the surface water sediment control system can be found in Volume 3, Tab 13, <br /> page 13-5 of the permit application. A list of sediment control structures, alone with references <br /> to appropriate exhibits for designs and cross sections,are found in Table 134 of the application. <br /> Calculations used to design these structures are given in appendix 13-2 of the permit <br /> application. <br /> Ten sediment ponds are in place, as previously approved by the Division and have been treating <br /> disturbed-area surface water runoff under the existing permit for the Roadside Mines. All ponds <br /> have performed well over this period. These ponds are described in the Summary, "Description <br /> of Operations Plan" section of this document. References to designs for these ponds and their <br /> locations are found in Tables 13-5 and 13-6 of the permit application. <br /> All but two sediment ponds are designed to contain the runoff and sediment from a 10-year,24- <br /> hour precipitation event. Sediment Ponds#1 and #2 were combined to contain the 25-year, 24- <br /> hour storm event. Sediment ponds #I, 42, #7, #8 and 011 require pumps as the principal <br /> dewatering mechanism because the surrounding ground elevations are higher than the sediment <br /> pond bottom elevations. The emergency spillways are designed to pass the 25-year, 24-hour <br /> peak flow. The outflow below the spillway is to be riprapped where necessary to control <br /> erosion. <br /> With the exception of approved small area exemptions,all surface runoff from disturbed areas <br /> is routed through one of ten sediment ponds: <br /> Area of Disturbance Sediment Ponds Other Structures <br /> Rail Loadout Ponds 91,#2 Berm, short ditch <br /> North Portal Ponds #4, #5 Diversion, berms and ditches <br /> North Decline Pond 97 Berm, ditches, sumps <br /> South Portal Ponds#8,#9 Diversion, berms, pipes <br /> CRDA-1 Pond#6 Berm, underdrain, ditches <br /> CRDA-2 Pond #10 Diversion,ditches <br /> CRDA-3 &CBA#2 Pond 411 Diversion,ditches <br /> There is no Sediment Pond 93. <br /> E. Impoundments <br /> The only impoundments existing within the permit area in addition to sediment ponds are <br /> sewage lagoons, Mine Water Discharge Pond #12, and three non-discharging sumps. A set of <br /> evaporative, non-discharging sewage lagoons has been permitted near the loadout for treating <br /> water from the Roadside Mine and the loadout. An additional sewage lagoon is present near the <br /> Roadside North Portal but is no longer in operation, and has been permitted for storage of <br /> construction dirt salvaged from diversion and culvert cleanout operations. <br /> 27 <br />