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<br /> <br /> <br />Ditch designs are summarized in Figure 1, Permanent Ditch Design Summary. <br />Ditch locations are shown on the Drainage and Sediment Control Map <br />(Map R-1 ). <br />Pond 4 <br />The proposed slope reduction activities east of Pond 4 will reduce pond <br />capacity. The new pond configuration will meet all requirements for permanent <br />impoundments in accordance with Rules 4.05.9 and 4.05.17 of the CMLRD <br />Rules and Regulations. The outlet structure has been designed to safely pass <br />the peak discharge from the 25-year, 24-hour event while providing 1 foot of <br />freeboard. <br />Pond 4 will employ the existing 42-inch corrugated metal pipe (CMP) riser with <br />a 30-inch diameter CMP barrel extending through the pond embankment as the <br />primary outlet structure. located at the base of the riser pipe is a 4-inch <br />diameter orifice which is used for dewatering. Pond 4 will utilize a ripraped <br />trapezoidal channel with a 5 foot bottom and 3H:1 V sideslopes as an <br />emergency spillway. The pond design and stage storage curve are shown on <br />the Pond 4 Design Map (Map R-3). The stage/storage curve illustrates <br />sediment and runoff storage capacity. The follov~ing summarizes the revised <br />Pond 4 design: <br />Three-Year Sediment Yield (ac-ft) <br />Elevation Three-Year Sediment (ft) <br />Elevation Dewatering orifice (primary outlet) <br />Volume 10-year, 24 Hour Event (ac-ft) <br />Volume Runoff and Sediment (ac-ft) <br />Elevation 10-Year, 24-Hour Event (ft} <br />Elevation Emergency Spillway Invert (ft) <br />Elevation Maximum Water Level 25-Year, 24-Hour Event (ft) <br />Elevation Top of Structure (ft) <br />Freeboard (ft) <br />0.29 <br />7539.2 <br />7539.2 <br />2.32 <br />2.61 <br />7546.9 <br />7547.0 <br />7548.0 <br />7549.00 <br />1.0 <br />13 <br />