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:~ <br />• <br /> <br /> <br />LIGHT-USE ROAD - BORRON DITCH <br />Design of the drainage ditch on the uphill side of the light-use road was <br />based upon Segment 6 (Drawing SGF-04) which is the segment with the largest <br />drainage area and which also has the least amount of ditch slope. <br />Segment No. 6 <br />Drainage Area 32.0 acres <br />Rainfall (10 yr., 24 hr.) 1.8 inches <br />Length of Drainage 2250 feet (Oak-Aspen; Hydrologic <br />d Elevation 800 feet Soil Grgup C, ground <br />Curve Number 67 Fig. S-3 cover density - 30X) <br />Runoff (10 yr., 24 hr.) 0.12 inches Table 5-3 <br />Peak Discharge 34 cfs/inch of runoff. Fig D-2 (Steep Slopes) <br />Peak Discharge (34 cfs/inch) (0.12 inches) <br />= 4.08 cfs <br />Channel Design <br />Channel length <br />d Elevation <br />Avg. Slope <br />Freeboard <br />Manning's n <br />Standard Barrow Ditch <br />A Zd2 <br />A (1.5)(1.0)2 <br />A = 1.5 ft2 <br />1000 feet <br />75 feet <br />7.5X <br />0.3 ft. minimum <br />0.040 earth channel <br />Table 3.1 <br />Triangular Channel <br />d-l J ' <br />~. s <br />i+-~i <br />a:i.S <br />Earthen Channel <br />(3) <br />