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• DIVERSION AND COLLECTION DITCH HYDRAULIC DESIGN CALCULATIONS <br />PERMANENT DIVERSION /1 <br />Permanent Diversion /1 is located along the west boundary of the refuse <br />disposal area as shown on Figure 1, Refuse Disposal Area Drainage Plan. <br />This diversion routes surface runoff from an undisturbed area south and <br />west of the refuse pile to the north where it loins with natural <br />drainage beyond the disturbed area. <br />The diversion is divided into three (3) sections (Sections A, B and C) <br />each having a different flow slope. All three (3) sections divert <br />undisturbed runoff from an area above the refuse storage area and are <br />therefore designed to safely pass the ]00-year, 24-hour storm event <br />providing 0.3 feet of freeboard. The peak flow calculated by SEDCAO+ is <br />52.50 cubic feet per second. The separate channel sections for <br />Permanent Diversion /1 are also shown on Figure 1, Refuse Disposal Area <br />• Drainage Plan. <br />Section A is designed as a trapezoidal shaped, vegetated channel with a <br />5-foot bottom and 2H:1V sideslopes. The channel section extends for <br />approximately 800 feet at a 0.5 percent slope. The design flow velocity <br />is only 3.1 feet per second, therefore, no erosion protection is <br />required for this section. <br />Section B is designed to the same configuration as Section A, extending <br />approximately 270 feet at a 1.9 percent slope. The design flow velocity <br />is 5.0 feet per second, therefore no erosion protection is required for <br />this section. <br />Section C is also a trapezoidal shaped channel with a 5-foot bottom <br />width and 2H:lY sideslopes. The channel extends approximately 500 feet <br />at a 4.0 percent slope. The calculated flow velocity (6.4 fps) exceeds <br />5.0 feet per second, therefore. rock riprap (D50 = 9 inches) will be <br />• installed in Section C to prevent erosion. Riprap will be placed to <br />-g- <br />