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<br />, ,\.' <br />I.ll II" <br /> <br />The Phelps System Improvements. In addition to the problems <br /> <br />encountered in the E-65 System a few others were also found <br /> <br />in the Phelps System (Figure 4). The main canal, for <br /> <br />instance, required extensive rehabilitation to restore the <br /> <br />needed capacity. A computer program was developed using <br /> <br />field and photogrammetric cross sections that could evaluate <br /> <br />the need for excavating, reslopin9, compacted embankment, or <br /> <br />slope protection. To minimize erosion and sedimentation, <br /> <br />canals were designed for a velocity of .55 to .64 m/s. In <br /> <br />cases where the velocity could not be maintained at these <br /> <br />levels, <br /> <br />slope <br />3 <br />m of <br /> <br />protection was prescribed. Approximately <br /> <br />640,000 <br /> <br />excavation was needed to restore 72 km of main <br /> <br />canal to its required capacity. All of the main canal <br /> <br />checks are being automated and a telemetry system installed <br /> <br />to improve central control of the main canal system. <br /> <br />~.'hen the original system was constructed in the 1940's, <br /> <br />surface water inlets were provided to admit storm water <br /> <br />runoff from adjacent lands into the canal. However, during <br /> <br />major storms, the canal capacity is exceeded and damages <br /> <br />result. <br /> <br />3 <br />Hydraulic studies indicated that a 740,000 m <br /> <br />regulating reservoir was needed to stabilize canal fluc- <br /> <br />tuations for a design storm of 5-year frequency and 12-hour <br /> <br />duration. The regulating reservoir could also be used to <br /> <br />increase downstream system capacity to meet changes in <br /> <br />demands. <br /> <br />-15- <br />