Laserfiche WebLink
X <br />• Ditch Sizing <br />Ditches are considered: <br />1) Haul Road Collection Ditch - Along east side of main haul road <br />south of HG-8 <br />2) Perimeter Ditch around top of HG-8 <br />3) Feeder Ditch into east end of HG-8 <br />4) Highwall Diversion Ditch built in 1979 <br />5) Highwall Diversion Ditch built in 1981 <br />6) Diversion Ditch draining off of property to the east <br />7) Collection ditch around overburden spoil dump. <br />The ditching around the overburden waste dump has already been <br />• constructed. <br />Ditch Calculations <br />1) Haul Road Collection Ditch <br />Drainage area 160 acres <br />Longitudinal slope 8% (0.08 ft./ft.) <br />Avg. ground slope 10% <br />CN 85 <br />1.8" rainfall, 0.65" runoff <br />Peak Flow 10-Year Storm 145 cfs/in. runoff @ 16% slope <br />(Table D-2 TR 55) <br />145 x 0.65 in. runoff = 94 cfs <br />Correct to 10% slope <br />. 94 x 0.86 = 81 cfs (Table E-1 TR 55) <br />