Laserfiche WebLink
i <br />• <br />46 <br />TABLE 3.6-13 <br />Diversion Ditch Design Criteria <br />Minimum Standards <br />nTTrw CPACTNC <br />* 5H : 1V regrade slope and 3H : 1V down slope berm results in 4H : 1V average <br />ditch side slope. <br />HB H/ j sb <br />12/7/84 <br />Update 8/87 <br />3-153 <br />REVISION <br />APPROVED <br />DATE <br />rn.,l 2-e"i1s+. <br />REMISED "rJc 2 4'87 <br />25 vertical <br />feet <br />50 vertical <br />feet <br />100 vertical <br />feet <br />Length of drainage area <br />1400 ft <br />1400 ft <br />1400 ft <br />Average slope of area <br />5H : 1V <br />5H : 1V <br />5H : 1V <br />Drainage area <br />4.02 acres <br />8.03 acres <br />16.07 acres <br />Slope adjustment factor <br />1.03 <br />1.03 <br />1.03 <br />25 -year, 24-hour rainfall <br />2.1" <br />2.1" <br />2.1" <br />Curve number <br />70 <br />70 <br />70 <br />25 -year, 24-hour runoff <br />0.28" <br />0.28" <br />0.28" <br />25 -year, 24-hour, peak flow <br />2.11 cfs <br />2.97 cfs <br />5.88 cfs <br />Ditch geometry <br />v -ditch <br />v -ditch <br />trapezoid <br />Manning's "n" <br />.035 <br />.035 <br />.035 <br />Ditch side slopes <br />* 4H : 1V <br />* 4H : 1V <br />* 4H : 1V <br />Ditch base width <br />-0- <br />-0- <br />1.76' <br />Ditch peak flow depth <br />0.42' <br />0.48' <br />0.44' <br />Ditch freeboard <br />0.5' - 1.0' <br />0.5' - 1.0' <br />0.5' - 1.0' <br />Total ditch depth <br />0.98' - 1.42' <br />1.05' - 1.48' <br />1.01' - 1.44' <br />Ditch gradient <br />2% - 47 <br />2% - 4% <br />2% - 4% <br />Peak flow velocity <br />2.27-2.93 fps <br />2.48-3.21 fps <br />2.88-3.69 fps <br />* 5H : 1V regrade slope and 3H : 1V down slope berm results in 4H : 1V average <br />ditch side slope. <br />HB H/ j sb <br />12/7/84 <br />Update 8/87 <br />3-153 <br />REVISION <br />APPROVED <br />DATE <br />rn.,l 2-e"i1s+. <br />REMISED "rJc 2 4'87 <br />