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<br />II <br /> <br />J08 <br /> <br />3. STORM DRAINAGE <br /> <br />I <br />I <br />I <br />II <br />II <br />I <br />I <br />II <br />I <br />I <br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Table 3-12 Effective Absolute Roughness and Friction Formula <br />Coefficients (7) <br /> <br />Conduit Material <br /> <br />Manning <br />n III '..I <br /> <br />Closed conduits <br />Asbestos-cement pipe <br />Brick <br />Cast iron pipe <br />Uncoated (new) <br />Asphalt dipped (new) <br />Cement.lined & seal coated <br />Concrete (monolithic) <br />Smooth forms <br />Rough forms <br />Concrete pipe <br />Plastic pipe (smooth) <br />Vitrified clay <br />Pipes <br />Liner plates <br />Open channels <br />Lined channels <br />a. Asphalt <br />b. Brick <br />c. Concrete <br />d. Rubble or riprap <br />e. Vegetal <br />Excavated or dredged <br />Earth. straight and uniform <br />Earth. winding. fairly uniform <br />Rock <br />Unmaintained <br />Natural Channels (minor streams. top width at flood stage < 100 It.! <br />Fairly regular section <br />Irregular section with pools <br /> <br />0.011.0.015 <br />0013.0017 <br /> <br />0.011.0.015 <br />0.012-0.014 <br />0.015.0.017 <br />0.011.0.015 <br />0011.0015 <br /> <br />0.011.0.015 <br />0,013.0,017 <br /> <br />0,013.0.017 <br />0.012.0.018 <br />0,011.0.020 <br />0,020.0.035 <br />0.030.040 <br /> <br />0.020.~.030 <br />0.025.0.040 <br />0.D30.o.045 <br />0.05Q.0.14 <br /> <br />0.03 .0.07 <br />0.04 .0.10 <br /> <br />Table 3-13 Values of Coefficient of Roughness (n) for <br />Standard Corrugated Steel Pipe (Manning's Formula)" <br /> <br /> Helical <br /> AMular 1 'hxV. in <br />Corrugations 22;" x 'h in B1.12) 221" x 'h in 113) <br /> All 8" 10" 12" 18" 24" 36" 48" 60" and Larger <br /> Diameters <br />Unpaved .024 .012 .014 .Oll .014 .016 .019 .020 .021 <br />25% Paved .021 .015 .017 .020 .019 <br />Fully Paved .012 .012 .012 .012 .012 <br /> Annular Helical - 3 1 I ,n <br /> 3 xl in 48" 54" 50" 66" 72" 78'. and Larger <br />Unpaved 027 .023 .023 .024 .025 ,026 .027 <br />25% Paved .023 .020 .020 .021 .022 .022 023 <br />Fully Paved .012 .012 .012 .012 .012 .012 012 <br />Corrugations 6 x 2 in 50" 72" 120" ISO" <br />Plain - Unpaved .033 .032 .030 .028 <br />25% Paved .028 .027 .026 .024 <br /> <br />"AISI <br /> <br />EXHIBIT NO.3 <br />