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<br />HYDROLOGIC DOCUMENTATION <br />SMALL AREA F~~TION <br />TOPSOIL AREA <br />The following calculations demonstrate the amount of sediment fence, straw <br />bales or gravel berm surface area required [o adequately handle the runoff from <br />the Yard Area SAE. <br />Runoff volume and peak discharge calculations were performed utilizing the <br />SEDCAD 4 computer model consistent with the methodology previously discussed in <br />this Exhibit. The sediment control structure was designed to handle the peak <br />discharge from a 10-year, 24-hour storm event. <br />1 Hydrology Inputs <br />All hydrology inputs are shown on the SEDCAD 4 computer printouts. <br />The CN numbers used for the SAE watershed were obtained from Procedures <br />for Determining Peak Flows in Colorado and Technical Release No. 55 <br />(USDA-SCS, 1980). Based on soil type and vegetation cover, curve numbers <br />were determined using Table 2-2a and 2-2d, USDA-SCS TR-55, for the <br />following conditions: <br />Reclaimed (< 2 years) <br />Soil Type: B <br />Ground Cover: <30$, Poor <br />Cover Type: Herbaceous <br />CN: BO <br />Undisturbed <br />Soil type: B <br />Canopy: 25~ <br />Cover Type: Brush or Brushes <br />CN: 69 <br />2 Hydrology Results <br />Peak Discharge In <br />10-year,29-hour event <br />3.4 cfs <br />3. Sediment Fence Requirements <br />Sediment Fence Permissivity: <br />Required Surface Area <br />10 gal/min/f t' or 0.022 cfs/f t2 <br />2.9 cfs / 0.022 cfs/ft~ = 131 ft' <br />The silt fence should be installed in accordance wi[h the manufactures <br />recommendations. Design assumes regular inspections and maintenance. <br /> <br />