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designated sump may move as mining phases are opened over time. Most storm water within the <br /> quarry will evaporate or infiltrate the processing area pad. However, the following described <br /> mechanism will be installed to ensure no stormwater is captured beyond 72 hours following the <br /> end of a storm event. After allowing sufficient time for sediment settling, clean, sediment-free <br /> water will be allowed to flow into and through a gated arrangement to control flow. This <br /> arrangement will be an elevated culvert that moves water from the processing area sump and <br /> under the CCP and WRL to the toe of the dump. This flow will be controlled and maintained at a <br /> rate similar to the flow the drainage and CCP culvert experienced prior to mining. By allowing <br /> stormwater collected in excess of 72 hours from the end of a storm event to enter a culvert prior <br /> to discharge, the rate and composition of discharge can be measured and monitored via the <br /> discharge points at the toe of the waste rock embankment. <br /> If Phases 4 and 5 are chosen to be mined, the affected hydrology will be engineered to applicable <br /> standards for water storage and may be, as required, reevaluated and submitted to the DRMS <br /> prior to excavation of Phases 4 or 5; therefore, hydrology below the 7850' level is not presented <br /> herein. <br /> The excavation of the quarry deposit itself will lead to different subbasin areas, particularly the <br /> creation of areas that are the quarry itself. The creation of the WRL just northeast of the quarry <br /> will modify the pre-mine drainage area where the WRL will be constructed. The areas created by <br /> these activities within the mining area can be seen on Map G-1 — Surface Hydrology: Mining <br /> Conditions. Curve numbers for mining areas are 89 due to disturbance of vegetation. Appendix <br /> 4 lists the mining storm event data for each area. The basin/area numbering corresponds to the <br /> numbering found on Map G-1 — Surface Hydrology: Mining Conditions. <br /> All water that falls on the stabilized surfaces of the WRL will percolate within the blasted rock <br /> surface of each lift. All stormwater which falls on the active working lift of the WRL will <br /> percolate within the porous working lift within 72 hours. The paired lift and berm configuration <br /> creates a stormwater containment sump on the lift behind that lift's stormwater berm that is <br /> greater than the maximum amount(based on 100-YR event) of stormwater that could fall on the <br /> active lift. Map G-2—WRL Surface Hydrology: Typical Waste Embankment Bench Cross <br /> Section shows how this is achieved. Sediment ponds will not be installed at the WRL toe to <br /> Young Ranch Resource . • ,. <br /> February 2020 G-3 <br />