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<br />'I <br /> <br />5 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />identified along the Ditch. Table 1 summarizes drainage areas upstream <br />from each node. As seen in Table 1 and Figure 2, nodes 1,2,3, and 5 are <br />located at Ditch crossings. <br /> <br />Peak Discharge Profile <br /> <br />Table 2 presents a 10-year peak discharge profile along the Ditch. <br />Also summarized is the existing capacity of each crossing. Currently, the <br />crossfngs are not capable of adequately conveying the 10-year peak Ditch <br />flows. The most severe bottlenecks are at nodes 1,2, and 5. Additional <br />bottlenecks in the system are the Phelps St. culvert and a small bridge <br />downstream from Highway 14. <br />The 10-year design peak discharges summarized in Table 2 were <br />computed using the relationships developed by Leaf and RCI (1983) and <br />presented in Figure 3. Figure 3 provides estimiltes of peak discharge for <br />various return intervals for undeveloped land. For developed areas, <br />peak flow estimates from Figure 3 are multiplied by adjustment factors as <br />follows: ' <br /> <br />Recurrence Interval (yrs. ) Peak Flow Adjustment Factor <br /> 2 2.0 <br /> 5 1.7 <br /> 10 1.5 <br /> 25 1.2 <br /> 50 1.1 <br /> 100 1.0 <br /> <br />The peaks summarized in Table 2 represent estimates from undeveloped and <br />dpveloped a~eas above each node. For example, at Node 2, the 10-year <br />peak is given by the following calculations: <br /> <br />Node 2: <br /> Undeve10pe2 Area Deve loped Area Peak Adj. Factor Adj.Peak <br />(mi. ) (mi .2) (c. f.s.) (c. f.s.) <br />1.564 290 1 290 <br /> .624 175 1.5 262 <br /> TOTAL 552 <br />