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~' <br />TABLE 3.6-13 <br />Diversion Ditch Design Criteria <br />Minimian Standards <br />nTTCn CPACTNC <br />i <br />• <br /> 25 vertical <br />feet SO vertical <br />feet 100 vertical <br />feet <br />Length of drainage area 1400 ft 1400 ft 1400 ft <br />Average slope of area SH : 1V SH 1V SH ; 1V <br />Drainage area 4.02 acres 8.03 acres 16.07 acres <br />Slope adjustment factor 1.03 1.03 1.03 <br />25-year, 24-hour rainfall 2.1" 2.1" 2.1" <br />Curve number 70 70 70 <br />25-year, 24-hour runoff 0.28" 0.28" 0.28" <br />25-year, 24-hour, peak flow 2.11 cfs 2.97 cfs 5.88 cfs <br />Ditch geometry v-ditch v-ditch trapezoid <br />Manning's "n" .035 .035 .035 <br />Ditch side slopes * 4H 1V * 4H 1V * 4H 1V <br />Ditch base width -0- -0- 1.76' <br />Ditch peak flow depth 0.42' 0.48' 0.44' <br />Ditch freeboard 0.5' - 1.0' 0.5' - 1.0' 0.5' - 1.0' <br />To[a1 ditch depth 0.98' - 1.42' 1.05' - 1.48' 1.01' - 1.44' <br />Ditch gradient 2X - 4X 2% - 4% 2% - 4% <br />Peak flow velocity 2.27-2.93 fps 2.48-3.21 fps 2.88-3.69 fps <br />* SH 1V regrade slope and 3H 1V down slope berm results in 4H 1V average <br />ditch side slope. <br /> <br /> <br />HB H/ j sb <br />12/7/84 <br />Update 8/87 <br />3-153 <br />REVISION <br />APPROVED <br />DATE 9-ay- s~ --... <br />r+~.~l T~i1 s+. <br />REMISED "rJc 2 t~'87 <br />