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�II■■ <br />Job Number: 93-419•26 <br />Calculated by: T. Fisher <br />Checked by: <br />Project: Everett Clinic <br />FIIO: F:\�\419�DOCS\PREC.W01 <br />Date: 04-Nov-93 <br />Date: <br />CALULATE THE WEIGHTED SCS CURVE NUMBERS FOR BASIN'C' <br />Cn^ <br />PFEDEVELOPED CONDITIONS AREA es <br />-gtass 0.09 98 <br />-pavement, buildings 0.03 <br />TOTAL = 0.12 Acres <br />WEIGHTED AVERAGE Cn VALUES: <br />•Predeveloped conditions <br />PERVIOUS IMPERVIOUS <br />86.0 98.0 <br />•Note: Hydrologic soil group 'C' was usod as the SCS <br />soils map indicates Alderwood (AgC) soils. <br />CALCULATE THE TIME OF CONCENTRATION <br />24 hour isopluvials: ref. KCSWDM 3.5,1-8 <br />2-year (P2) = 1.55 inches/day <br />Sheetflow: Tt=[0.42•(Ns•L)^.8]/[(P2^05)*(So^0.4)] <br />Conc.11ow: Tt = L/(60"Ks•(So ^ 0.5)] <br />Predeveloped conditions So T� <br />Segment Status Length Ns Ks �%� (min) <br />���% 3.0 <br />C1 - C2 lawn <br />34 0.150 NA 11.5% <br />(sheet) <br />C2 - C3 lawn 130 <br />(conc) <br />NA 11 1.3°h 1.7 <br />Total = 4.7 min <br />SUMMARY OF INPUT DATA FOR KCSWDM'S ITYD PROGRAM <br />Predeveloped <br />Apei <br />(Ac) <br />0.09 <br />Cn <br />GZ�] <br />Aimp Cn Tc P2 <br />�q�� (min) (��) <br />0.03 98.0 4.7 1.55 <br />