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SECTION 3 – STORMWATER <br />24 <br /> Table 4: NOAA Atlas 14 First Quartile, Median 24-hr Rainfall Distribution <br />Cumulative <br />Time <br />(%) <br />Cumulative <br />Precipitation <br />(%) <br />0% 0% <br />5% 12% <br />10% 27% <br />15% 40% <br />20% 51% <br />25% 61% <br />30% 68% <br />35% 73% <br />40% 78% <br />45% 82% <br />50% 85% <br />55% 88% <br />60% 91% <br />65% 93% <br />70% 95% <br />75% 97% <br />80% 98% <br />85% 99% <br />90% 99.5% <br />95% 99.8% <br />100% 100% <br />5.) Allowable Concentrated Release Rate <br />i.Calculations shall be performed for a 24-hour duration storm for existing and proposed <br />conditions to determine discharge rates produced and storage required. <br />ii.The maximum allowable release rate for storage facilities shall not exceed the <br />downstream channel capacity or 10-year predeveloped rate. Note that releases from <br />the storage facility due to infiltration are not considered as part of the release rate <br />requirement because they are not part of the concentrated discharge release at the <br />outlet. <br />iii.Discharge control structures shall be multi-stage and capable of limiting 2, 10, and <br />100-year storms to the minimum requirements outlined in the previous section.