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<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. ]4). 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 />during the sluicing tests. During these tests, the flow through the Englewood intake was set at <br />30 ft'/s. <br /> <br />The city of Englewood currently operates at radial gate settings ranging from 2 to 8 feet to sluice <br />sediment for riverflows ranging from 2DD to 3,000 ft'/s. At 3,000 ft'ls, the upstream water intakes <br />must be closed due to sediment buildup, even with the sluice gate fully opened. These sluicing flows <br />would draw boaters to the barrier and pin the boats against it; therefore, the sluicing flows would <br />be unacceptable for boating. <br /> <br />In order to improve sluicing and reduce the risk to boaters, the low wall currently in front of the <br />intakes was increased in height to match the present elevation of the primary intake wall <br />(5296.5 feet). All of the water entering the intake area was forced to enter at the upstream end <br />of the intake. The high wall extends downstream to the crest of the existing dam and has a I-foot <br />opening, as shown on figure 3, to allow small amounts of debris to exit the sluiceway. In order to <br />assess the effect of this change, velocities were measured in the intake area with and without the <br />high wall in place. Table 2 summarizes the data. <br /> <br />As shown by the data, the sluicing action is greatly enhanced by adding the high wall. The same <br />velocity can be obtained at a 25-percent gate opening with the high wall as with a ]OO-percent gate <br />opening with a low wall. When the sediment test was conducted with 3,000-ft'/s riverflow and a 30- <br />percent gate opening with the high wall, the primary intake area was almost entirely sluiced out; <br />therefore, sluicing is much more effective with the high wall. <br /> <br />The radial gate can be operated automatically (as it is now) to maintain a constant water surface <br />of about 5290 feel. At riverflows of 50 to 150 ft'ls, all or most of the flow enters the Englewood <br />intake channel. As the riverflow increases, the radial gate can be adjusted to facilitate sluicing. The <br />model tests indicated that a sluiceway gate opening of about 50 percent would provide maximum <br />sluicing capacity (table 2). <br /> <br />Approach flow to Englewood intake, - With the high wall in place, an open bar barrier or other type <br />of open barrier will be required to prevent boaters from entering the sluice at the upstream end. <br /> <br />10 <br />