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Peabody does not anticipate any pit pumpage or other inflow to the pond <br />• at this time. <br />SPILLWAY <br />Sediment Pond 004 provides for a combination of principal-emergency <br />spillway to safely discharge the runoff from a 25-year, 24-hour storm. <br />The principal spillway inlet will also be used as the non-clogging <br />dewatering device and is located at an elevation higher than the maximum <br />sediment storage volume. The principal spillway inlet is located in a <br />position on the embankment so as to prevent short-circuiting as much as <br />possible. The stage-discharge relationship of the emergency spillway <br />inlet was calculated using SEDIMOT II, while the stage-discharge <br />relationship of the principal spillway inlet was calculated using the <br />orifice flow equation. <br />Q = C Ao V2gH <br />where: <br />• C = 0.6 (coefficient of discharge) <br />Ao = 0.0021 ft.z (5/8 inch diameter) <br />g = 32.2 ft/sec.2 <br />H = 0 to 6.8 ft. (above the opening) <br />Elevation H ft. cfs <br />5661.3 0.0 0 <br />5662.0 0.7 0.008 <br />5664.0 2.7 0.017 <br />5665.2 3.9 0.020 <br />5666.0 4.7 0.022 <br />5668.1 6.8 0.026 <br />Table 3 is a summary of the spillway data. <br />• <br />5 <br />