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Horton's parameters for infiltration (page 5 attachment 4)were selected for NRCS <br /> Hydrologic soils groups C and D. NRCS data for the drainage area is shown in <br /> attachment 5 (NRCS 2017). There is a bit of Hydrologic Soils Group A at the top of the <br /> basin, but this group has higher infiltration values than what was used in CUHP. Use of <br /> Horton's parameters associated with NRCS Hydrologic soils groups C and D is felt to be <br /> conservative. All other values shown in Attachment 4 are default values. <br /> CUHP Results <br /> Attachment 6 summarizes the storm hydrographs produced by a simulation run of the <br /> data shown in Attachment 4. The attachment quantifies what is intuitively obvious;the <br /> majority of runoff comes from Basin's(sub-catchments) 1 and 2. <br /> Hydraulics/Routing <br /> The routing portion of the analysis takes the runoff and moves it downstream through the various <br /> conveyance methods. The first step in this process is to utilize the SWMM model to gain an estimate of <br /> runoff,velocity and depth at certain points. The second step starts into the design process where flows <br /> are checked for super or subcritical flow and determination of energy and the need for reduction, in <br /> particular where runoff must turn direction. <br /> SWMM <br /> EPA's SWMM is set up to determine rainfall, route it to a node, usually the downstream end of <br /> the sub-catchment basin, and then route that flow by a link, or conveyance method. Since <br /> UDFCD requires the use of CUHP(UDFCD 2016), setting up the SWMM Model becomes an <br /> exercise in setting up nodes and links. <br /> SWMM Nodes <br /> The Nodes are designed to receive the inflow from each sub-catchment and the link <br /> upstream. Inflow to each catchment generated by CUHP was entered in the time series <br /> Water' <br /> 6 07/30/2017 <br />