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1980 <br /> 3. . Time of Concentration (TC) = 15 min. (given) <br /> 4. Determine Rainfall Intensity Factor (i) <br /> (i) = 4.9 in/hr - (from Plate 5-3) <br /> 5. Q = C(i)(A) <br /> Q = .43(4.9)(80) = 168.56 cfs <br /> Table 5-2 <br /> VALUES OF RUNOFF COEFFICIENT (C) FOR RATIONAL..FORMULA <br /> Land use C Land use C <br /> Business: Lawns: <br /> Downtown areas 0.70-0.95 Sandy soil, flat, 2S 0.05-0.10 <br /> Neighborhood areas 0:50-0.70 Sandy soil, average, 2-7: 0.10-0.15 <br /> Sandy soil, steep, 7S 0.15-0.20 <br /> Residential: Heavy soil, flat,_ 2S 0.13-0.17 <br /> Single-family areas 0.30-0.50 Heavy soil, average, 2-1: 0.18-0.22 <br /> Multi units, detached 0.40-0.60 Heavy soil, steep, 7 % 0.25-0.35 <br /> Multi units, attached 0.60-0.75 <br /> Suburban 0.25-0.40 Agricultural land: <br /> Bare packed soil <br /> Industrial: Smooth 0.30-0.60 <br /> Light areas 0.50-0.80 Rough 0.20-0.50 <br /> Heavy areas 0.60-0.90 Cultivated rows <br /> Heavy soil no crop 0.30-0.60 <br /> Parks, cemeteries 0.10-0.25 Heavy soil with crop 0.20-0.50 <br /> Sandy.soii no crop 0.20-0.40 <br /> Playgrounds 0.20-0.35 Sandy soil with crop 0.10-0.25 UsEo 0.40 <br /> Pasture <br /> Railroad yard areas 0.20-0.40 Heavy soil 5-0.45 <br /> Sandy soil 0.05-0.25 <br /> Unimproved areas 0.10-0.30 Woodlands 0.05-0.25 <br /> Streets: <br /> Asphaltic 0.70-0.95 <br /> Concrete 0.80-0.95 <br /> Brick 0.70-0.85 <br /> Drives and walks 0.75-0.85 <br /> Roofs 0.75-0.95 <br /> Note: The designer must use judgement to select the %ppropriate C value within the <br /> range. Generally, larger areas with permeable soils, flat slopes and dense <br /> vegetation should have lowest (C) values. Smaller areas with dense soils, <br /> moderate to steep slopes, and sparse vegetation should be assigned highest <br /> (C) values. <br /> Source: American Society_ of Civil Engineers _ <br /> V-5 <br />