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<br /> <br />DRAFT <br /> <br />1. The second ramp in the boatchute should be placed at an elevation 0.4 foot above the <br />design elevation (defined in fig. 27) of the downstream control. <br /> <br />2. Both ramps should be 10 feet long and 0.75 foot high; the top of the ramps should be <br />horizontal. <br /> <br />3. The slope of a line connecting the crest of the dam with the lip of the second ramp should <br />be Ito 10 (fig. 4). <br /> <br />4. A low flow notch should extend from the crest through the first ramp. <br /> <br />The general boatchute configuration is acceptable for head drops from 2 to 3.5 feet. The length <br />of the boatchute will increase as the head drop increases. <br /> <br />Both boatchutes were tested in the laboratory for river discharges ranging between 100 and <br />3,000 ft'/s. Photographs of boatchute operation with fmal design configuration are shown on <br />figures 29 through 33. <br /> <br />Flow patterns. - Time lapse photographs of 8-foot boats approaching Union Avenue dam and <br />traveling between boatchutes 1 and 2 were used to define flow patterns. Lights on the boats <br />produced streak lines. The grid spacing was 18 feet prototype. A strobe unit flashing at constant <br />time intervals (At) produced images of the boats. The velocity of a boat during each interval can <br />be determined by dividing the distance the boat traveled by At for the photograph. <br /> <br />Surface velocities and flow lines are shown on figures 34 and 35 in the approach channel to Union <br />Avenue dam at flows of 1,000 and 1,500 ffls. Surface velocities and flow lines in the pool between <br />boatchutes 1 and 2 are shown on figures 36 through 38 for discharges ranging between 500 and <br />1,500 ff Is. Figure 39 also shows the path of a boat passing over the main crest. <br /> <br />The model tests indicate that a boat will take approximately 1 minute (prototype) to float from <br />boatchute 1 to boatchute 2 at 500 ft'/s. At 1,500 ff Is, it will take about 30 seconds to reach <br />boatchute 2. It will take about 40 seconds to reach Union Avenue dam from the Union Avenue <br />bridge at 1,000 ft'/s. <br /> <br />Sediment Studies <br /> <br />Sluicing flows. - Initially, the model was operated for riverflows from 50 to 3,000 ft'/s. Sand spilled <br />over the low wall in front of the Englewood intake for various operating conditions. Operating the <br />radial gate and sluiceway moved sand through the intake areas; however, some sand deposited <br />below the level of the intakes. For low flows, the amount of sand deposited depends on the <br />proportion of water being drawn off through the Englewood water intakes compared to the <br />sluiceway flow. When the radial gate was fully opened, sand was cleaned from the intake area. <br />Tests were conducted to determine how much sluicing could be tolerated during riverflows which <br />would be boatable. An open barrier was placed in the model in front of the water intakes to <br />exclude boaters (fig. 14). To determine tolerable sluicing, model boats were placed in front of the <br />intake. As the radial gate opening was increased, the current began drawing the boats toward the <br />barrier. At high gate openings, the model boats were pinned against the barrier by the current. <br />This condition was considered to be unacceptable. Figure 40 gives the boating limits determined <br /> <br />9 <br />