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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 feet <br />V = Velocity <br />S = Slope <br />D50 = 1.43 feet <br />Pond Dewatering Pipes <br />17 inches <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)A 1.85)(q- 1.85)/(dA4. 8655) <br />f= 0.2083'(( 100 /F6)A1.85)'(F7A1.85 )/(F8A4.8655) 0.863 /100ft <br />Slope Pipes 2 % to compensate for head loss. <br />PR -07 EXH -8 -10 <br />2/03 <br />DEWATERING PIPE <br />DISCHARGE UNDER FALLING HEAD <br />Assume surface area of ponds is constant only height <br />varies. <br />POND B POND C <br />--- -- - - -- --- - - -- -- <br />AREA OF POND <br />--------- --- - - - - -- <br />26000 23000 <br />SQUARE FEET <br />DIAMETER OF PIPE <br />6.0 6.0 <br />INCHES <br />AREA OF PIPE = a <br />0.20 0.20 <br />SQUARE FEET <br />C = LOSS COEFFICIENT <br />0.65 0.65 <br />H1 = BEGINNING HEAD <br />8.00 8.000 <br />FEET <br />H2 = ENDING HEAD <br />0.00 0.000 <br />• <br />t = time to lower the surface level <br />of the pond (H1 -H2). <br />t = 2A'(Hl A.5 - H2A.5)/C'a'(2G)A.5 <br />t = 143675 127097 <br />SECONDS <br />I= 1.66 1.47 <br />DAYS <br />Average flow in pipe: <br />366 324 <br />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)A 1.85)(q- 1.85)/(dA4. 8655) <br />f= 0.2083'(( 100 /F6)A1.85)'(F7A1.85 )/(F8A4.8655) 0.863 /100ft <br />Slope Pipes 2 % to compensate for head loss. <br />PR -07 EXH -8 -10 <br />2/03 <br />