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• 4.8.1.4 Sediment Ponds <br />All runoff from disturbed areas at Trapper are routed through one or more sediment ponds. These ponds <br />are designed to control the sediment load in the water discharged from the Trapper pertnil area. <br />All future sediment ponds to be built at Trapper Mine are designed using hydrologic modeling techniques <br />to predid the peak settleable sediment load during the 10-year, 24-hour precipitatbn event. Detailed <br />design plans will be submitted to the Dhrlsion at least 80 days prior to construction of the structures. <br />Epsting ponds which were not designed using these techniques have been re-evaluated to ensure <br />adequacy of each sediment control system. The results of atl hydrologic models are presented in <br />Appendix Q, Dreinage and Sediment Control Plan. <br />Sediment load in surface water discharged from Trepper Mine is controlled by routing the water through a <br />series of one or more sediment ponds. Sediment ponds have been or will be buiR in all major drainages <br />at Trapper prior to topsoil removal for advancement of adhre pits. Sediment pond locations are shown on <br />Map M51, Drainage and Sediment Control. <br />As previousy mentioned, all ponds have been designed or confirmed for adequacy, using hydrology and <br />sedimentology modeUng. Trapper spent considerable time during the summer of 1988 in discussans with <br />the Division in order to determine the applicable curve numbers and sedimentology parameters for design <br />• of drainage and sediment control systems. The agreed upon parameters are shown in Appendbc Q, <br />Drainage and Sediment Control Plan, Section CIA, Curve Number Determinations, and Sectbn XIII, <br />Sedimentology Parameters. <br />The current drainage and sediment control plan calls for the use of 41 sediment ponds either singly or in <br />series over the year permit term (1998-2002). Design information for each pond is summarized in <br />Table 4.8-0, Sediment Pond Summary Information. Details of all currently designed sediment ponds are <br />included in Append'a Q, Drainage and Sediment Control Plan. <br />• 4-184 <br />P~-~V <br />Nlp~( i ~~ ~1g99 <br />