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J <br /> N�r�eolt L�.t3.� <br /> � �- � :� �� <br /> p <br /> I consuBine enpineers <br /> STORPI URAIN STORAGE REQUIREMENTS <br /> Drainage Basin <br /> A = a. � 2 acres Area of Basin <br /> Ce = o. � ,� , Existing coefficient of imperviousness of <br /> . Basin ground <br /> Cd = � . 5'S Developed coefficient of imperviousness of <br /> Basin as planned. Calculated Page 18. <br /> L = i�o 'e ,oi,feet Lenath (maximum) of overland tra�zl to <br /> �g��e �,$ �o Design point. <br /> S = % Slope (averaoe) `rom Basin high, point to <br /> low point (on wa�ercourse) <br /> Vr = o',�° `t./sec. Runoff rate Chart 1, page 25. <br /> T� �q. � "minutes Time of c ncentr�tion fron formula: <br /> ( 10 + (L� (60) = T <br /> I = /• 3 in./hr. Roinfall intensi�y from Chart <br /> rainfall curve (ioyear storm) <br /> pe . = o •$8 cfs Existing outflotiv off of s�te from equation: <br /> Cel A = Qe <br /> Q� = p. -7� cfs F�ax;mum outflo�a perritted per acre <br /> irnperviousness from formula: Qo - 4e��d <br /> T = 3�•3 minutes Storage time (to capacity) from formula: z a yT <br /> T = -2 S� 7' z�/% <br /> �U <br /> V = i si 8 cf/A/C Required volure of storaae per zcre in Easin z s „r <br /> s d fron equation: VS = �i;� �,- _ � — <br /> /O 4� <br /> % - s— <br /> Vt = / B S 8 cubic feet Fequired volume of storaae for this dasin from <br /> eouation: Vt = VS ACd <br /> Ref: "Storm drainaae ccntrol , requirements and auidelines" !� -- <br /> t Kir�g County Public :;orls uepartment; i•1dy, 1°79. <br /> i00 Iioyd blog., s�o"le. wa 9b101 («5) C22-5o22 <br /> onchoroge los aneeles portiand secifle <br />