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1. (90 pt) Design the stormwater-collection pipe (concrete, n=0.013, minimum size of 12 in and possible pipe sizes are 12 in, 15 in, 18 in, 21 in, 24 in, 30 in, 36 in, 42 in and 48 in.) for the housing subdivision in Figure below to ensure the full flow velocity in the pipe is greater than 3.5 ft/sec. The data for each drainage area (basin) contributing flow to the manholes is provided in the following table, including the inlet time (T.) 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/t40.50), where i- intensity in in/hr, and td -storm duration time of concentration in minutes. Basin 2 Inlet manhole Storm pipe Surface runoff Basin 2 Basin Basin 4 River Basin с Area (acres) Ti (min.) 1 2 3 4 2.2 1.8 2.2 1.2 12 10 13 10 0.3 0.4 0.3 0.5 lalala Stormwater Length Upstream Downstream Pipe (ft) Elevation Elevation (ft) (ft) AB 200 24.9 22.9 CB 300 24.4 22.9 BD 300 22.9 22.0 DR 200 22.0 21.6 1.0 08 0.6 depth of water in pipe damcter of Pepe 04 Ratio of 02 V 0 0.2 0.4 0.6 and W 0.8 10 12