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Two ditch designs are proposed for each the east and west ditches. <br /> Based on the critical slope calculations for each ditch, a ditch section <br /> will be constructed with riprap or without riprap, depending on whether <br /> the ditch's slope is steeper or flatter than critical slope. Each ditch <br /> will have a minimum of one foot of freeboard included in the total <br /> depth. This will allow the ditch to be field-located as close as <br /> practical to the proposed disturbance area but still control all runoff <br /> and direct the flow to Pond 005 (see Exhibit 13-4) . <br /> Following is a summary of "Alternative A" and "Alternative B" ditch <br /> design to be used for East and West Ditch. <br /> Ditch Factor <br /> North Ditch West Ditch <br /> Q 10.5 cfs 1.0 cfs <br /> Z 2:1 2:1 <br /> Shape V-ditch V-ditch <br /> "Alternate A" <br /> n (without riprap) 0.025 0.025 <br /> do 1.11 ft. 0.43 ft. <br /> Sc 1.3% 1.8% <br /> Vc 4.23 fps 2.65 fps <br /> "Alternative B" <br /> n (with riprap) 0.04 0.04 <br /> Based on the above results, the East Ditch will be constructed with the <br /> following minimum dimensions. <br /> "Alternate A" (without riprap) : <br /> Minimum depth = 3.0 ft. <br /> Side Slopes = 2:1 <br /> Slope = 0% to 1.3% <br /> Maximum Velocity = 4.23 fps <br /> Q = 10.5 cfs <br /> Manning's N = 0.025 <br /> Shape = V-ditch <br /> 12 <br />