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• <br /> RULE 2 PERMITS <br /> erosion control and surface stability. Sediment will be removed from all sedimentation ponds when <br /> the volume of sediment accumulates to 60% of the design sediment storage volume or when <br /> sufficient volume is not available to treat the predicted runoff and sediment volume from a 10- <br /> year, 24-hour storm event.. The accumulated sediment found in the ponds will be removed and <br /> placed in existing topsoil stockpiles if the sediment meets the appropriate topsoil criteria,otherwise <br /> disposed of in the pit backfill.Sedimentation pond removal is discussed in Section 4.05. <br /> The location of all sedimentation ponds and diversion structures to be constructed within the <br /> permit area are shown on Map 12. These maps also show the locations of watershed boundaries <br /> from which, along with other sources, the design criteria were established. Generally, ponds and <br /> spillways were sized and placed according to such hydrologic factors as required sediment storage <br /> volume,rate of flow and volume of flow for the appropriate storm event. <br /> Pond embankments, slopes, spillways and construction methods have been designed according to <br /> such engineering factors as structural integrity and stability, slope and surface stability; adequacy <br /> in height, size and shape to provide sufficient volume for sediment and detained water and <br /> selection of proper spillways and outlet devices,passing of design storm events and proper outflow <br /> rates. All ponds have been designed under the direction of a qualified, registered professional <br /> engineer. <br /> The purpose of the sedimentation ponds is not only to provide a final measure to prevent additional <br /> contributions of sediment outside the permit area, but also to provide a means of <br /> compliance with all applicable effluent limitations, especially with respect to total suspended <br /> solids or settleable solids, as required. <br /> The effluent quality is regulated by Section 4.05.2 and by the National Pollutant Discharge <br /> Elimination System (NPDES) Permit. The NPDES Permit was issued by the State of Colorado <br /> Department of Health under the National Pollutant Discharge Elimination System, established as <br /> a result of the Clean Water Act(33 U.S.C. Section 1251, et. seq.). <br /> The engineering parameters for the various sedimentation ponds are included in Exhibit 7, <br /> Hydrology Information. The engineering design parameters for the various diversion ditches are <br /> also included in Exhibit 7,Hydrology Information. Cross sections for the sedimentation ponds and <br /> the designs for the emergency and primary spillways are shown in Exhibit 7, Hydrology <br /> Information. <br /> Topsoil Removal Plan <br /> Prior to any mining related disturbances, topsoil will be removed from the site to be disturbed as <br /> discussed in Section 4.06 and redistributed or stockpiled as necessary to satisfy the needs of the <br /> reclamation timetable. <br /> Topsoil will be removed in the permit area by bulldozers, loaders or scrapers as described in <br /> Section 2.05.3. <br /> Rule 2 Permits 2.05-10 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />