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of the runoff being released from behind the berm and into the right -of -way of CR -84. <br />Secondly, rip rap is to be placed just downstream of both the proposed berm weir outlet <br />and the concrete pan. <br />The Rational Method was used to calculate the hydrological information found within <br />this study, utilizing the software program Hydraflow Hydrographs 2004. Furthermore, <br />Manning's Equation was used to calculate the drainage capacity of the concrete pan, <br />utilizing the "Hydrology" tool found within the software program Autodesk Land <br />Desktop 3. See the attached worksheets and hydrographs for a detailed hydrological <br />analysis. Table 1 below summarizes the hydrological results for the sub - basins and for <br />the two design points of the access. Table 2 summarizes the drainage capacity of the <br />concrete pan. <br />BASIN <br />AREA <br />(acres) <br />C10 <br />C100 <br />Q10 <br />(cfs) <br />Q100 <br />(cfs) <br />Al <br />0.68 <br />0.20 <br />0.41 <br />1.33 <br />2.05 <br />A2 <br />1.55 <br />0.26 <br />0.43 <br />3.07 <br />4.72 <br />O <br />2.04 <br />0.20 <br />0.39 <br />3.09 <br />4.75 <br />DESIGN <br />POINT <br />BASIN <br />COMBINATION <br />V 1 0 <br />(cu. ft.) <br />V100 <br />(cu. ft.) <br />Q10 <br />(cfs) <br />Q100 <br />(cfs) <br />DPI <br />A2+0 <br />4,991 <br />7,681 <br />5.19 <br />7.99 <br />DP2 <br />DP1 + Al <br />5,194 <br />8,315 <br />5.19 <br />8.09 <br />Table 1: Sub - basins and Design Points <br />HEIGHT <br />WIDTH <br />MANNING'S <br />SLOPE <br />CAPACITY <br />CAPACITY <br />OF PAN <br />OF PAN <br />"n" <br />(ft/ft) <br />VELOCITY <br />FLOWRATE <br />(in) <br />(ft) <br />(fps) <br />(cfs) <br />4 <br />13.17 <br />0.015 <br />0.02 <br />4.24 <br />9.30 <br />Table 2: Concrete Pan As Built <br />In conclusion, the concrete pan as installed, with a capacity of 9.30 cfs, is sufficient to <br />carry the 100 -year peak runoff of 7.99 cfs from Sub - basins A2 and O. This stormwater <br />runoff, combined with the runoff being released from Sub -basin Al, results in an overall <br />100 -year peak runoff rate of 8.09 cfs, which is released into the existing downstream <br />roadside drainage Swale. <br />Cordially, <br />Joseph V. Gagliano <br />Cherokee Clay Mine Access Permit - Drainage Study page 2 of 2 file ( D:U OBS\2008\2008- 010\Drainage- ConcretePan\2008010- <br />Drainage.doc) <br />