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<br />• <br />• <br />exceeds 5.0 feet per second. therefore, rock rlprap (D50 ~ 8 inches) <br />will be installed in Section C to prevent erosion. The rlprap will be <br />placed to an approximate depth of 18 inches along the channel bottom and <br />sideslopes. Appropriate bedding material will be placed as a base for <br />the rlprap. <br />Design details for each channel section are summarized in Figure 3. <br />Design Detail - Refuse Collection Ditches. <br />South Refuse Collection Ditch <br />The south refuse collection ditch extends around the southwest corner of <br />the refuse storage pile and along its southern toe. This ditch collects <br />surface drainage flowing off the southern slope of the pile and runoff <br />from a small undisturbed area southwest of the pile. and routes it to <br />the east to Sedimentation Pond 4. The south collection ditch is divided <br />into four (4) channel sections, each having different channel slopes and <br />configurations as shown by Figure 1, Refuse Disposal Area Drainage Plan. <br />Sections A and B are designed as trapezoidal channels with 5-foot bottom <br />widths and 2H:lY sideslopes. Section A extends for approximately 920 <br />feet at a 1.4 percent slope. and Section B extends for approximately 470 <br />feet at a 2.2 percent slope. The flow velocities for Section A and <br />Section Bare 3.4 fps and 4.1 fps. respectively. No erosion protection <br />is required for these sections. <br />Section C is designed as a trapezoidal channel with an 8.5-foot bottom <br />width and 2H:1V sideslopes. The channel section extends approximately <br />950 feet at a 4.4 percent slope. The design velocity 1s 5.0 fps. <br />therefore. no erosion protection is required. <br />Section D is designed as a trapezoidal channel with a 5-foot bottom <br />width and 2H:1V sideslopes. The channel extends approximately 300 feet <br />at a 5.0 percent slope. The calculated velocity (6.5 fps) exceeds 5.0 <br />-15- <br />