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L <br /> <br />1 <br /> <br /> <br />C' <br /> <br />Ll <br /> <br />1 <br /> <br /> <br /> <br />1 <br /> <br />1 <br /> <br />Ci <br />h. Sediment Pond Design <br />The minimum sediment pond size and maximum allowable release rate for each sub-basin within the <br />Parkdale site were determined using Water Quality Capture Volume (WQCV) and Extended Detention <br />Basin (EDB) sizing criteria specified by the Urban Drainage and Flood Control District (UDFCD) in its <br />Urban Storm Drainage Criteria Manual, issued January of 2007. The Extended Detention Basin design <br />method is based on the contributing area of a given drainage basin, and the approximate percentage of <br />impervious terrain corresponding to that basin. To perform this analysis an impervious percentage of <br />5% was assumed for each of the quarry basins, and for both basins contributing flow to the sand and <br />gravel pit. All specified sediment ponds included in this report shall be built entirely below grade to <br />remove the necessity of temporary berm construction. The minimum sediment pond size for each of the <br />quarry basins and sand and gravel pit basins is defined within the following table: <br />Basin Designation Basin Area <br />(acres) Min. Sed. Pond Vol. <br />(acre-feet) <br />A 132.0 0.477 <br />B 109.5 0.398 <br />C 50.7 0.183 <br />D 19.0 0.069 <br />E 21.8 0.079 <br />F 30.4 0.110 <br />Table : Minimum Sediment Pond Volumes <br />i. Maximum Allowable Release Rates <br />In addition to minimum sediment basin size, recommended maximum allowable release rates were also <br />calculated following the criteria specified within UDFCD's Urban Storm Drainage Criteria Manual. <br />The method specified for determining the recommended maximum allowable release rates is based upon <br />the specification of various unit release rates, in terms of the peak runoff rates of each drainage basin, as <br />they correspond to varied storm intensities of varied statistical return periods. These percentages are <br />based upon the specified NRCS hydrologic soil group determined for each basin. As stated within the <br />Hydrologic Criteria section of this report, an NRCS soil type of D was used for each basin. The <br />maximum allowable release rates calculated for each of 6 storms is specified in the following table in <br />application to each of the previously defined drainage basins. <br />Parkdale Quarry Drainage Report I Fremont County File No. CUP 07-003 <br />