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C] <br />Appendix 4B <br />T -1 AND T -2 SPILLWAYS <br />5/6 <br />Since there is a ditch above the ponds that diverts all surface flow away from the ponds, <br />the peak flow that T -1 and T -2 will need to handle is the 70 gpm flow from the long pond or <br />the decant flow from the 25 -year event. The long pond has the capacity to decant from <br />one 6 -inch pipe at 177 gpm and two four inch pipes at 64 gpm each or 128 gpm. Design <br />the open channel for 305 gpm + 10% = 336 gpm (0.75 cfs) <br />Manning's Equation <br />Flow In a Triangular Channel <br />Depth D 0.550 Feet <br />Slope S 0.010 Express as a Decimal <br />Manning's "N" N 0.030 Express as a Decimal <br />Side Slope X 1.500 Slope = X:1 <br />Area= (X *D`)= 0.45 Feet` <br />Wetted Perimeter--2 *_[((X *D)` +D`) "`] _Y . - _ - - —1:98- - Feet— - - - — <br />R= Area/Wetted Perimeter 0.23 <br />V= (1.49 /N) *(R- ') *(S "`)= 1.86 Ft/Sec <br />Q =AXV= 0.84 CFS <br />Q REQUIRED 336 GPM = 0.75 CFS <br />The spillway will be a triangular channel 0.55 feet deep with 1.5h:ly side slopes. With a <br />freeboard of 1.0' the required depth of the spillway is 1.55 feet. The flow velocity is slow <br />enough that erosion will not be a problem. <br />• This triangular open channel spillway design is applicable to the spillway between treatment <br />ponds T -1 and T -2, the spillway that flows out of treatment pond T -2, and the open channel <br />between treatment pond T -2 and outfall 001. See section C -C on drawing D -2 -5. <br />PIPE SPILLWAYS BETWEEN T -2 AND OUTFALL 001 <br />Discharge through a submerged tube <br />Diameter of Pipe <br />Area of Pile <br />C = Loss Coefficient <br />H = Head of Spillway <br />Q = C A (2GH) ^.5 <br />Q = One 4 -Inch Pipe <br />Q = Two 4 -Inch Pipes <br />4.000 Inches <br />0.0873 Square Feet <br />0.500 <br />0.167 Feet <br />0.1431 Cubic Feet Per Second <br />64 Gallons Per Minute <br />128 Gallons Per Minute <br />Diameter of Pipe <br />6.000 Inches <br />Area of Pile <br />0.1963 Square Feet <br />C = Loss Coefficient <br />0.500 <br />H = Head of Spillway <br />0.250 Feet <br />Q = C A (2GH) ^.5 <br />0.3939 Cubic Feet Per Second <br />Q = One 6 -Inch Pipe <br />177 Gallons Per Minute <br />The calculations and information presented on this page were prep, rd" y me in j1, and during the <br />month of October 2011, and the information presented is true an correct -to_the best,of;my knowledge <br />and belief. <br />4 <br />©o <br />Pg9 °ol b �v <br />Do o <br />00000000,10 oa <br />°�� /o�aca� ��� <br />c a o ¢+a� <br />TR -26 <br />P-9-9 <br />Rev 10/21/11 <br />