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82 <br /> USUMMIT <br /> DESIGN AND ENGINEERING SERVICES <br /> Project: LRD Date: 12.2.2022 Revision: <br /> Project No: 22-0214 By: WRW <br /> DetentionWet • • . Calculations (Schools) <br /> Drainage Area 1 <br /> Input values in red <br /> Drainage Area Pervious Surface Area <br /> Total Drainage Area sf 11145,154 Mana ed Pervious Area sf 0 <br /> On-site Drainage Area (sf) 1,145,154 Unmanged Pervious Area (pasture) (sf) 0 <br /> Off-site Drainage Area (sf) 0 Forest(sf) 0 <br /> Total Pervious Area (sf) 0 <br /> Impervious Surface Area <br /> On-site Buildings/Lots (sf) 70,400 <br /> On-site Streets (sf) 264,200 <br /> On-site Parking (sf) <br /> On-site Sidewalks (sf) <br /> Other On-site (sf) <br /> Future (sf) 0 <br /> Off-site (sf) 0 <br /> Existing BUA* (sf) 0 *=Report only amount of existing BUA that will remain after development. Do not report <br /> Total Impervious Area (sf) 334,600 any existing BUA that is to be removed and which will be replaced by new BUA <br /> Required Surface Area Required Storage for 1st inch of runoff <br /> Total Drainage Area = 26.29 ac Simple Method <br /> Total Impervious Area = 7.68 ac <br /> Percent Impervious = 29.22% Rv = 0.05 + 0.009(I) <br /> Design Rainfall Depth = 1 in I = % impervious = 29% <br /> Average Perm. Pool Depth = 3.37 ft <br /> Max. Perm. Pool Depth = 3.5 ft <br /> SA/DA Ratio = 1.02 Rv = 0.31 in <br /> Surface Area Required = 11647 sf Volume = 29866 cf <br /> 0.27 ac <br /> Calculation Methods are taken from NCDEQ Stormwater Minimum Design Criteria,Latest Version <br /> Surface Area Required at Normal Pool 11,647 sf <br /> Temporary Storage Volume Required 29,866 cf <br /> Ai <br /> Pagel of 4 <br />