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<br />' <br />' TABLE D.9-2 <br />CULVERT SIZING <br /> RIVER-HAUL ROAD CROSSING <br /> Design flow (100-yr event) 3,540 cfs (calculated from Table G.2-5) <br />' For three 54-inch diameter CMP with 10-ft headwater depth: <br /> Assuming outlet control, each culvert can pass about 180 cfs or a combined total <br /> of 540 cfs. <br /> The net balance of 3,000 cfs will be handled with a low velocity drainage Swale <br /> across the haul road. <br />' SWALE DESIGN <br />Broad crested weir: Q - 2.5 B(H)aiz <br />' B(avg) 280 <br />= 3,000, H 2.64 ft <br />Flow velocity, V Q/A - Q/(B (avg) H) <br />t 4.1 fps (adequate) <br />CULVERT OUTLET RIPRAP DESIGN <br />' Riprap size: d5 18" <br />Armored reach: ~ - 50' <br /> SOUTH WASTE ROCK DISPOSAL FACILITY <br /> HAUL ROAD CULVERT (southern culvert) <br />' Catchment area (acres) 1,160 <br /> Overland slope (%) 11.7 <br /> C <br />draulic length (ft) 12,600 <br /> <br />' N 0 <br /> 100-yr precip (inches) 2.90 <br /> Calculated peak flos (cfs) 365 <br />' Based on the calculation for the river-haul road crossing above, one 72- <br /> inch diameter CMP will suffi ce (about a 10.5-ft headwater depth will be <br /> required). Culvert to be placed at a three percent minimum slope to ensure <br /> inlet control. <br /> CULVERT OUTLET RIPRAP DESIGN <br /> Riprap size: ds 12" <br />A <br />d <br />h <br />3 <br />~ <br /> rmore <br />reac <br />: <br />= <br />5 <br /> <br /> <br />1 <br />