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} <br /> DRAINAGE STUDY FOR AA RENTALS <br />� COMMERCIAL EXPANSION <br /> SILUtR LAKE, WASHIN�aTON <br /> _ <br /> 0 <br /> -i <br /> �. <br /> c� <br /> I. PEAK v.UNOFF RATE FOR 10-YEAR STORM �" <br />' RATIONAL METHOD: Q = CIA WHERE: C = Runoff Coefficient �; <br /> I = Rainfall Intensity „� <br /> A = Acres, Area `^m <br /> T = Time of Concentration � o <br /> C m o <br /> c'� <br />' om <br />, UNDEVELOPED CONDITIONS m—�+ I <br /> .. <br /> A = 0.47 ac c Z � <br /> � = i <br /> A Existing Developme^t = 0.31 ac ��, � <br /> A New Development = C.16 ac $,� <br /> -i m , <br /> _ (0 9) t0.3�1 7+ 0.1 0.16 = 0.628 = 0.63 a �, � <br />� � Ext'st c�i m � <br />� � 3 N <br /> T _ 10 + 141 = 13.26 = 13.3 r'� <br /> � 60 �i 0.72 <br /> .�m <br />� a <br />'� I = 1.6 in/hr A <br /> -� <br />� D. <br />; q10 = 0.628 (1.6) (0.47) = 0.47 cfs Z <br /> � _ . <br /> .. <br />�'� N <br /> iI . RUNOFF COEFFICIENT AVERAGE z <br /> 0 <br /> � <br /> ., <br /> �DeV ' 0.9 m <br /> c. M��c� , <br /> III. MAXIMUM OUTFLOW PER ACRE IMPERVIOUSNESS (CFS/AC �'� �F��� <br /> O ^�•l� <br /> Q = Rilowable Outflow , ` � � <br /> � Acreage x Runoff Coefficient Cp s <br /> ooz',;a� . <br /> �^� ..�� ����� <br /> . <br /> ;��.. � 1 ..::•�''G\j.J <br /> 10 Year `'+�.:;qw,-` <br /> q = 0.47 <br /> ° 0.9 0.47 <br /> Q = 1.116 <br /> 0 <br />