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REVISED <br />7/30/85 <br />area is 11 acres. The watershed of Pond E is shown on Map 15, Fish <br />e <br />Creek Tipple Surface Facilities and Structures. <br />The hydrologic and hydraulic specifications which contributed to the <br />design of Pond E are summarized in Table 1, Sedimentation Pond E Design <br />Specifications. Supporting calculations are presented in Tables 2 <br />through 4. The permanent pool capacity is the volume of required <br />sediment storage. The required sediment storage volume was calculated <br />using the MUSLE, as shown in Table 2, Sedimentation Pond E Design <br />Calculations. <br />The dewatering devise used to achieve adequate detention time is an <br />orifice set at the required sediment storage elevation on the riser <br />pipe. The size of the orifice is set by routing the 10 -year, 24-hour <br />runoff event through the impoundment so as to achieve a theoretical <br />detention time of at least 24 hours, as shown on Table 4, Sedimentation <br />Pond E Riser Pipe Design Calculations. The top of the riser pipe is set <br />at the elevation of the combined volume of sediment storage and runoff <br />\ from the 10 -year, 24-hour event. A trash rack is provided at the top of <br />the riser to prevent clogging. <br />The riser pipe and outlet conduit are sized to convey the design flood <br />event. A rating table of the outlet works is given in Table 4, <br />Sedimentation Pond E Riser Pipe Design Calculations. Anti -seep collars <br />are installed on the outlet conduit to prevent piping. A splash basin <br />is provided at the discharge point in accordance with Rule 4.05.7. <br />The top of the dam is set one foot above the elevation of the routed <br />25 -year, 24-hour runoff event. The height (H) of the embankment is <br />measured from the upstream toe to the crest elevation. Top width is set <br />by the equation 4,=(H+35)/5. Side slopes are set at 3:1, which is <br />considered stable under saturated conditions. <br />The embankment foundation area is excavated to competent strata with <br />side slopes of 1:1. The entire embankment area is stripped of topsoil <br />and other organic matter. Fill material consists of non -swelling clay, <br />-4- <br />