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Table 5. Area Storm Events. <br /> Event Probability Event Rainfall (inches) <br /> 100-YR 24-HR 4.24 <br /> 25-YR 24-HR 3.08 <br /> 10-YR 24-HR 2.45 <br /> After Reclamation <br /> Reclaimed conditions include revegetation across the entire site that will create the same <br /> conditions as baseline pre-mining vegetation. The curve number for all reclaimed areas is <br /> assumed to be no greater than that of baseline conditions. The lack of firm compaction of <br /> material beyond that provided by tracked equipment during slope grading in reclamation will <br /> lead to greater infiltration of surface water runoff than baseline conditions. Additionally. the <br /> fractured nature of the underlying and unmined substrate will continue to allow stormwater <br /> infiltration into the underlying groundwater system. Therefore, all stormwater that falls within <br /> the reclaimed areas of the site, including a 100-year storm scenario, will infiltrate the relatively <br /> porous reclaimed surface within 72 hours. <br /> Stormwater Runoff Calculations <br /> The 100-year 24-hour storm even was used as the basis for the runoff calculations. The expected <br /> rainfall from this event is 4.24 inches. The two pits will be more than capable of carrying the <br /> entire capacity of the runoff event this large during mining and reclamation. This will allow time <br /> for the surface water to infiltrate or evaporate, or to settle before pumping. if necessary, after 72 <br /> hours. However, only infiltration and evaporation will occur after reclamation. <br /> The runoff was calculated in AutoCAD's Hydraflow software using the TR-55 method. The <br /> calculations are provided in Appendix 4. A summary of the results demonstrating that the pit's <br /> have the capacity to capture the runoff from this event is in the tables below. <br /> Siskin Pit <br /> I e' ichi & \ti�nci:tte. <br /> Januarl 2024 G-3 <br />