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Peabody does not anticipate any pit pumpage or other flow inta~ the pond at • <br />this time. <br />Soillway (Pond 0081 <br />Sediment Pond 008 provides for a separate principal and emergency <br />spillways to safely discharge the runoff fran a 25-year, 24-hour storm. <br />Zhe principal spillway orifice inlet will also be used as the nonclogging <br />dewaterirg device and is located at an elevation hider than the maximum <br />sediment storage volume. The principal spillway orifice inlet is located <br />in a position on the embarilanent so as to prevent short-circuiting as much <br />as possible. The stage-discharge relationship of the emaxg~ancy spillway <br />cannel was calculated using SEDCAD+, as was the stage-discharge <br />relationship of the principal spillway orifice. To be conservative, it <br />was ---~^^^~' that there was no flora through the principal spillway in <br />determirwxj the stage height for the 25-year and 100-year storm events. <br />Table 7-6f-16 is a summary of the spillway data. <br />TABLE 7-6f-16 • <br />Spillway Data Summary <br />SaAima.+t Pond 008 <br />Principal Spillway: Type Perforated Riser Inlet <br /> (Q°1P) <br />Grifice Diameter 4.7-inch <br />Crrifice Elevation. 7011.5 <br />Barrel Diameter 24.000-inch <br />Riser Diameter 24-inch <br />Length of Harrel 120.00 ft <br />Vertical Head Drop 17.50 ft <br />Manning CAef 0.025 <br />l0-year, 24-hour <br />Peak Stage Elevation 7014.4 <br />Top of Riser Elevation 7015.0 <br />F]nergency Spillway: Type Trapezoidal Channel <br />Bottom Width 20 ft <br />length 30 ft <br />Side Slopes 3h:ly <br />Cutfall Slope 27~ <br />D 50 Size 1.50 ft <br />Inlet Elevation 7016.0 <br />25-year, 24-hour • <br />Peak Elevation 7017.2 <br />7-6f-16 Revised 08/21/91 <br />