Laserfiche WebLink
1 <br /> SECTION 3 <br /> HYDRAULIC CRITERIA <br /> 3.1 Manning Equation <br /> The Manning Equation shall be used to determine the capacity of <br /> open channels and enclosed gravity conduits : <br /> Q = AV = 1.486 R2/3 S1/2 A (3-1) <br /> n <br /> Where Q is the flow rate in cubic feet per second <br /> A is the cross sectional area of the flow in square feet <br /> V is the flow velocity in feet per second <br /> R is the hydraulic radius in feet <br /> S is the slope in feet per foot <br /> n is the Manning coefficient <br /> Values of the Manning coefficient for various pipes and open <br /> channels are given in Table 3-1. <br /> 3 .2 Velocity <br /> Closed conduits shall be designed so that the velocity is not <br /> less than 2 feet per second when the conduit is flowing full. <br /> For pump discharge lines , the velocity shall not exceed 10 feet <br /> per second. Velocities in unlined open channels shall not exceed <br /> s <br /> those values shown in Table 3-2. <br /> 3.3 Surcharge <br /> No surcharge shall be allowed in the design of gravity drain <br /> pipe lines . <br /> 3-1 <br />