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• Riprap Sizing -Down Face of Embankment -Pond C <br />D50 =Size of Riprap <br />D50 = ((V X S^.17)!7.58))^2 <br />D50 = Diameter in feef <br />V =Velocity <br />S =Slope <br />D50 = 1.43 feet <br />Pond Dewatering Pipes <br />17 inches <br /> DEWATERING PIPE <br /> DISCHARGE UNDER FALLING HEAD <br /> Assume surface area of ponds is constant only height varies. <br /> POND B POND C <br />--------- --------- <br /> <br />AREA OF POND --------- --------- <br />26000 23000 <br />SQUARE FEET <br /> DIAMETER OF PIPE 6.0 8.0 INCHES <br /> AREA OF PIPE = a 0.20 0.20 SQUARE FEET <br /> C =LOSS COEFFICIENT 0.65 0.65 <br /> H1 =BEGINNING HEAD 8.00 8.000 FEET <br /> H2 =ENDING HEAD 0.00 0.000 <br />• <br /> t =time to lower the surface level of the pond (H1-H2). <br /> t = 2A'(H1 ^.5 - H2^.5)/C'a'(2G)^. 5 <br /> t = 143675 127097 SECONDS <br /> t = 1.66 1.47 DAYS <br /> Average flow in pipe: 366 324 GPM <br />Reference Civil Engineering Handbook, <br />Urquhart, Fourth Edition, Page 4-34. <br />CHECK FRICTION LOSS IN PIPES <br />FRICTION LOSSES IN PIPES <br />C =surface roughness constant -PVC 150.0 <br />q =flow in gpm 360.0 <br />d =inside diameter of pipe, inches 6.0 <br />f=0, 2083 ((100/C}^ 1.85}(q^ 1.85}/(d^4.8655} <br />f=0.2083'((100/F6)^1.85)'(F7^1.85~(F8^4.8655) 0.863 /100 ft <br />Slope Pipes 2 % to compensate for head loss. <br />PR-07 EXH-8 -10 <br />2/03 <br />