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The total acre feet of water that will be generated for sub basin "OS 1" is 1,79 =78,097 cubic feet, for <br />"OS2" IS 0.3623 15,782.50 Cubic feet. The operator is proposing to build each pond for 120% capacity <br />with properly rip rapped emergency spill way. OS1 to handle 85,150 cubic feet and OS2 will be built to <br />handle 25,125 cubic feet of water. The sizing should be more than adequate to handle the flow. As a <br />point source both ponds will be an NPDES discharge point. My only recommendation will be for the <br />operator to place feet markers in the middle of the pond or where appropriate to check for periodic <br />sediment load and clean up of the ponds as needed. <br />NOTE: Did not check the channel sizing for the watershed; however as a standard rule, a flow velocity in <br />excess of 5ft/second is considered an erosive velocity and will require some sort of rip rap to increase <br />the roughness coefficient and decrease the rate of erosion. Operator mentioned rip rap utilization, <br />maybe they mean utilizing additional rip rap in the channels in addition to the spill way area. Given the <br />Manning's N utilized that could be the case. In the future if TR.55 method is utilized operator should <br />proved the Curve # used for the watershed. Since the applicant is using the ponds as structural BMPS, it <br />is acceptable for this design.