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1 <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br />1 <br /> <br />TABLE D.9-2 (con't) <br />CULVERT SIZING <br />HAUL ROAD CULVERT (northern culvert) <br />Catchment (acres) 276 <br />Overland Slope (%) 12.0 <br />Hydraulic Length (ft) 8,700 ft <br />CN 70 <br />100-yr precipitation (inches) 2.9 <br />Calcualted Peak Flow (cfs) 108 <br />A 48" diameter CMP is adequate <br />HW/D = 1.5 <br />Culvert to be placed on a nomical 3 percent grade to ensure inlet control. <br />WASTE ROCK DISPOSAL AREAS A AND B <br />HAUL ROAD/DRAINAGE CROSSING <br />Catchment (acres) 355 <br />Overland slope (%) 10 <br />Length (ft) 6,600 <br />CN 70 <br />100-yr precip (inches) 2.90 <br />Calculated peak flow (cfs) 215 <br />-SWALE SIZING <br />Q 2.5 B(H)3/z <br />For B(avg) 100 ft and Q = 215 <br />H 0.9 ft <br />V = Q/(BH) = 2.4 fps (adequate) <br />CULVERT BETWEEN THE EAST AND WEST PIT <br />Peak Strom flow 90 cfs (Table D.9-1 West Pit East Ditch) <br />1) Assume inlet control <br />2) HW/D < 2 <br />From design nomograph (AISI, 1983): <br />(CMP Culvert dia = 42" is adequate) <br />(Alternative design 2 - 33" dia culvert with HW/D = 1.5) <br />Culvert to be placed on a nominal 3 percent grade to ensure inlet control <br />governs. <br /> <br />