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. <br /> �: <br /> Gxamplr. <br /> A 3-acre site in the Narbeck Creek Urainage Basin is to be developed <br /> irorn its present forested condition to a small shopping center. <br /> For purposes of this example, assume the site is not located in a <br /> critical dr:ainage are�a. Paved parking areas and rooftops will cover <br /> 95% of this site with the balance to be landscaped. There is no <br /> off-site drainage and the most distant pointfrom 4he outletis 630 <br /> feet. The approximate slope of the site is 4%. <br /> SOLUTION: <br /> 1. from table 1, an appropriate cexistis .05 <br /> 2. from table I, velocity = .5 ft/sec therefore, <br /> Tc = 630 + 10 = 31min. <br /> .5�60) <br /> 3. from figure 1, intensity, "i", = 1.02 in/hr <br /> � 4. Since there is no off-site drainage, the tributary area = area of the site =3.0 aa'es. <br /> 5. Qa11ow = (.05) (1.U2) �3) _ .153 <br /> 6. This site is not in the combined sewer area, therefore, the design storm is <br /> , <br /> the 25-year storm. <br /> '• - . � 7. (a) Cdev - (0.95) (0.9) + (0.2) (.OS) = 0.865 <br /> 1 ,; �. " <br /> . ' : ' (b) Qo = �allow = 153 = .059 <br /> , ,� (A)(Cde �3�(0.865) <br /> l �� <br /> ��,f' � fc) T = -25 + 270G = -25+ 2706 <br /> �,� Q� .059 <br /> T = 189 <br /> (d) Vs = 4329T -40QoT <br /> T + 25 - <br /> � ' Vs = 4329(189) -40(0.59) (184) <br /> `� `� 189 + 25 <br /> C'' .�`� <br /> . <br /> � Ys = 3377 cf/acre imperviousness '. <br /> � (e) Vt F(Vs)(A)(Cdev� ��-- <br /> �t = (3377) (3 (0.8G5)J <br /> Vt = 8763 cf <br />