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F. Conveyance Analysis <br /> Powdermill Gulch Creek: <br /> Since the site has a time of concentration under 60 minutes, the Rational Method will be used to <br /> calculate flows for the conveyance analysis. For this conveyance analysis, the peak flow from the <br /> ' entire basin will be routed through a 12-inch pipe at minimum slope to verify the capacity of the <br /> pipes in the system. <br /> Q = CiA <br /> C = 0.81 (per calculation in Table 3B in Section VIII) <br /> i = m/T" = 7.83/(6.77°582) = 2.57 in/hr <br /> m=7.83 (25-year) <br /> n=0.582 (25-year) <br /> T=6.77 min (see calculations below from StormShed) <br /> Directly Connected TC Calc <br /> I Type I Description Length Slope Coeff Misc TT <br /> Sheet Smooth Surfaces.: 0.011 1167.00 ft 11.00% f 0.0110 iT.5 in 3.46 min <br /> [Channel (interm) 'Concrete pipe (n=0.012) 69.00 ft !3.08% 0.0120 ��0.15 min <br /> [Channel (interm) Concrete pipe (n=0.012) .568.00 ft 0.50%0 i0.0120 r 13.15 min <br /> Directly Connected TC 6.77min <br /> A = 1.37 (per calculation in Table 3B in Section VIII) <br /> ' Q = 0.81 x 2.57 x 1.37 = 2.85 cfs <br /> See the figure below for conveyance calculations using the hydrology function in AutoCAD 2007 <br /> that shows that a 12" pipe at a minimum 0.5% slope has sufficient capacity to convey the full basin <br /> ' flow: <br /> I <br /> 6/16/201 1 Stormwater Site Plan Page 32 <br />