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TABLE 13-3C-11 <br />As-Built Storage Capacity Summery <br />Pond 005 <br />Capacity <br />Elevation Stage (At.-Ft J Description <br /> .. <br />~ <br />6857.0 0 0.00 Excavetion <br />Bottom df ~POnd <br />6864.4 7.4 2.5 100X Sediment S[o rage <br />6872.2 15.2 8.3 Elevation of Principal Spillway <br />6873.0 16.0 9.1 10-Yr, 24-Xr. Peak Stage <br />6874.1 17.1 10.2 Crest of Emergency Spillway <br />6875.4 18.4 11.5 25-Yr., 24-Rr. Peak Stage <br />6875.7 18.7 11.9 100-Yr., 24-Rr. Peak Stage <br />6879.6 22.6 16.9 Top of Embankment <br />Peabody does not anticipate any other inflow to the pond at this time. The principal <br />spillway will be noncLogging and will automatically dewater the ponding area to maintain <br />the design capacity for the runoff volume for a 10-year, 24-hour storm event. Any <br />additional dewatering required will be done by transporting the water to another pond for <br />treatment, or discharging the water by utilizing the 4-inch PVC dewater pipe in accordance <br />with the approved Colorado NPDES permit. <br />SDIIlwHYS <br />This sediment pond has two separate spillways; a principal and an emergency. Please see <br />Exhibit 13•SA for location of spi llweys. The principal spillway consists of a 24-inch <br />diameter drop inlet corrugated metal pipe (CNP) with a trash rack at the inlet. This pipe <br />wil( keep the pond level et the E872.2 elevation. Maximum estimated elevation (peak <br />stage) above the principal spillway with the passage et the 10-year, 24-hour event will be <br />6873.0, this leaves 1.1 feet [o the emergency spillway (elevation 6874.1). <br />The embankment portion of the emergency spillway consists of a trapezoidal channel as <br />shown on Exhibit 13-SA. Assuming the principal spillway was plugged, the trapezoidal <br />channel could safely pass the runoff volume from the 25-year and 100-year, 24-hour storm. <br />The emergency spillway outflow channel consists of a riprepped trapezoidal channel (see <br />Addendum D for specifications). Peek estimated stage elevation with the passage of the <br />100-year storm is 6875.7. This leaves 3.9 feet of freeboard to the top of embankment. <br />13-3-12 Revised 08/11/92 <br />