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<br />L <br /> <br /> <br /> <br />1 <br /> Basin A Basin B Basin C Basin D Basin E Basin F <br />Statistical <br /> Max. Max. Max. Max. Max. Max. <br />Storm Return Release Release Release Release Release Release <br />Period (yrs) <br /> Rate (cfs) Rate (cfs) Rate (cfs) Rate (cfs) Rate (cfs) Rate (cfs) <br />2 5.28 4.38 2.03 0.76 0.87 1.22 <br />5 22.44 18.62 8.62 3.23 3.71 5.17 <br />10 39.60 32.85 15.21 5.70 6.54 9.12 <br />25 68.64 56.94 26.36 9.88 11.34 15.81 <br />50 89.76 74.46 34.48 12.92 14.82 20.67 <br />100 132.00 109.50 50.70 19.00 21.80 30.40 <br />Table : Maximum Allowable Sediment Pond Release Rates <br />As noted, the preceding table relates the maximum allowable sediment pond release rates to storms of <br />six different return periods. However, the method outlined within the Section 3.2.1 of UDFCD's Urban <br />Storm Drainage Criteria Manual Vol. 2 makes no reference to the time period of occurrence for a given <br />' storm. Thus, in the interest of clarification and operator guidance, both the 6-hour and 24-hour <br />approximate rainfall depths will be considered to serve as alternate triggers necessary to ascend higher <br />rates of stormwater release from the stormwater sediment ponds. Those approximate rainfall depths as <br />reported within the Precipitation-Frequency Atlas of the Western United States Volume III- Colorado <br />are contained within the following table: <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />Statistical Storm <br />Return Period (yrs) 6-Hour rainfall <br />Depths (in) 24-Hour Rainfall <br />Depths (in) <br />2 1.1 1.6 <br />5 1.4 2.0 <br />10 1.6 2.4 <br />25 2.0 2.8 <br />50 2.2 3.0 <br />100 2.4 3.4 <br />Table : 6-Hour and 24-Hour Rainfall Depths <br />Parkdale Quarry Drainage Report I Fremont County File No. CUP 07-003 M <br />