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<br />,- <br /> <br />5 <br /> <br />identified along the Ditch. <br />from each node, As seen in <br />located at Ditch crossings. <br /> <br />Table 1 summarizes drainage areas <br />Table 1 and Figure 2. nodes 1.2.3. <br /> <br />upstream <br />and 5 are <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 />crossings 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 />downstre3m from Highway 14. <br />The lO-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 esti:TkItes 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.) <br /> <br />Peak Flow Adjustment Factor <br /> <br />2 <br />5 <br />10 <br />25 <br />50 <br />100 <br /> <br />2.0 <br />1.7 <br />1.5 <br />1.2 <br />1.1 <br />1.0 <br /> <br />The peaks summarized in Table 2 represent estimates from Imdeveloped and <br />developed a~f'as above each node, For examp12. at Node 2. the 10-year <br />peilk is given l,)' the following calculaticns: <br /> <br />Node 2: <br />Undevelope2 Area <br />(mi. ) <br /> <br />1.564 <br /> <br />Developed Area <br />(mi .2) <br /> <br />.624 <br />TOTAL <br /> <br />Peak Adj. Factor Adj.Peak <br />(c. f.s,) ( c, f. s.) <br />290 1 290 <br />175 1.5 262 <br /> 552 <br />