Laserfiche WebLink
<br />Page 22 <br /> <br />100 year Storm <br /> <br />= (66 C.) A <br />1 <br /> <br />V100 <br />Q100 <br /> <br />= 1.0A <br /> <br />where: <br /> <br />v = Volume of pond in cubic feet <br />C. = Percent Imperviousness of basin <br />A1 = Area of Basin in Acres " <br />Q = Release rate in cfs for x year <br />x <br />storm <br /> <br />*Note: The area of ba~in for purpose of computing pond volumes <br />shall be the area being developed. The area of basin used for <br />determining the release rate shall be the entire basin inter- <br />cepted by the detention facility which includes the area of <br />basin contributing offsite flows. <br /> <br />A suggested procedure for computing the required detention facili- <br />ties is included in Appendix C. <br /> <br />2) Detention Facility Construction Criteria <br /> <br />a. Detention Ponds <br /> <br />Minimum turf slope 2% <br /> <br />Minimum paved slope (parking areas) = .75% <br /> <br />Pond embankment side slopes: <br />grassed 4:1 desirable <br />3: 1 maximum <br />protected 2:1 desirable <br />1:1 maximum (wi slope stabilization) <br /> <br />Minimum freeboard at H100 = 1.0' <br />= 0.25' for parking lots <br />and cul-de-sacs <br /> <br />Outlet pipe diameter - 12" minimum with <br />orifice control if required <br /> <br />b. Release Structures: The release structures shown in Design <br />Standards 43 and 44 in the Engineering Regulations, Construc- <br />tion Specifications and Design Standards are to be used unless <br />an alternate is approved by the City Engineer. <br /> <br />c. Detention Duration <br /> <br />Land Use <br />Parks, Playgrounds, <br />other <br />Parking Lots <br /> <br />5 year <br />6 hrs <br /> <br />100 year <br />24 hours <br /> <br />2 . 5 hours-/' <br /> <br />4 hours" <br />