Design the stormwater-collection pipes in Problem 11.8.13 given the following data changes. The upstream elevation for pipe CB is 23.5 ft instead of 24.4 ft, the inlet time for basin 2 is 14 min instead of 10 min, and the downstream elevation for pipe DR is 22.0 ft instead of 21.6 ft.
Problem 11.8.13
Design the stormwater-collection pipes (concrete; minimum size of 12 in.) for the housing subdivision in Figure P11.8.13. The data for each drainage area (basin) contributing flow to the manholes is provided in the following table, including the inlet time (Ti) and the runoff coefficient (C). In addition, stormwater-pipe information is given, including the ground elevation at each manhole. The rainfall intensity-duration relationship for the design storm can be described by i = 18/(td0.50), where i = intensity in in./hr, and td = storm duration = time of concentration in minutes.

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Basin I O) Inlet/manhole Storm pipe Basin 3 Basin 4 Basin 2 Surface runoff Figure PI1.8.13 Stormwater Length Upstrean Basin (acres) (min) C Pipe (ft) Elevation (t Elevation (ft) 0.3 0.4 0.3 0.5 22.9 22.9 22.0 21.6 200 300 12 AB CB BD DR 24.9 24.4 22.9 22.0 2.2 2.2 1.2 10 200