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o Sheet flow or Concentrated Flow Dispersion is deemed infeasible due to lack of available <br />space for a vegetated flow. The slow infiltration rate of the native soils is expected to <br />cause ponding issues for yard areas if this BMP is used. <br />5.4 Water Quality <br />The existing 6' diameter Downstream Defender model by Hydro International has a treatment <br />flow rate of 4.1 cs with an overflow rate of 32 cfs. See Appendix B for the 2016 Storm Pond <br />Memorandum. The flow rates for the existing development for water quality are 1.00 cfs and <br />for the 100-year are 8.42 cfs. There is sufficient capacity in the existing Downstream Defender <br />for the minor increase in net impervious area of our redevelopment. <br />The additional water quality design flow rate generated by the increased impervious area of <br />0.04 cfs is shown in the WWHM report included in this section. <br />Treatment Capacity = 4.1 cfs <br />Water Quality Design Flow Rate = 1.00 cfs + 0.04 cfs = 1.04 cfs <br />Therefore, the existing water quality unit has sufficient capacity. <br />22723 <br />