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Job Number: 93-419-26 FIIB: F:\93�419�DOCS\PREA.W�i <br />Calculated by: T. Fisher Date� 04-Nov-93 <br />Checked by: Date: <br />Project: Everett Clinic <br />CALULATE THE WEIGHTED SCS CURVE NUMBERS FOR BASIN'A' <br />PREDEVELOPED CONDITIONS AREA Cn" <br />-grass 0.72 86 <br />-gravel drive 0.12 89 <br />-pavement, buildings 0.06 98 <br />TOTAL = 0.90 Acres <br />WEIGHTED AVERAGE Cn VALUES: <br />PERVIOUS IMPERVIOUS <br />-Predeveloped conditions 86.0 92•2 <br />•Note: Hydrologic soil group'C' was used as the SCS <br />soils map indicates Aldervvood (AgC) soils. <br />CALCULATE THE TIME OF CO�fCENTRATION <br />24 hour isoaluviais: <br />2•year (P2) = 1.55 inches/day ref. KCSWDM 3.5.1-8 <br />Sheettlow: Tt= [0.42"(Ns�L!^.9]/[(P2^0.5)"(So^0.4)] <br />Conc. ilow: Tt = LI[60•Ks•(So ^ 0.5)] <br />Predeveloqed conditions So Tt <br />Segmeirt Status Length Ns Ks <br />���� �gb� (mIn) <br />A1 - A2 lawn 23 0.150 NA 18.396 �•8 <br />(sheet) <br />A2 - A3 lawn 30 0.150 NA 5.3°k 3.6 <br />(sheet) <br />A3 - A4 gravel 107 0.011 NA 6.0% 1•2 <br />(sheet) <br />A4 - A5 g�ass 62 0.0 17 1.8% 0.5 <br />(ditch) Total = 7.1 min <br />SUMMARY OF INPUT DATA FOR KCSWDM'S NYD PROGRAM <br />qpe� Cn Aimp Cn Tc P2 <br />�A�� �q�� (min) (in) <br />Predeveloped: 0.72 86.0 0.1 B 922 7.1 1.55 <br />