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The ditch is about one and a half miles long. The ditch leaks into a downhill irrigated field when <br /> operated for long periods of time which will require lining of those sections. An estimated 1500 <br /> feet of ditch is expected to be lined with the clay material to be used in the embankment. The <br /> wetted perimeter of the ditch is about 25 feet and assuming 3 feet of lining material, about 4200 <br /> cubic yards of material would first be removed and replaced with about 5500 cubic yards of clay <br /> material. The estimated cost in 1995 is $100,000, based on $5 per cubic yard for removal and <br /> waste and $10 per cubic yard for overhaul and compaction. <br /> 12.2 Outlet Works: The outlet is a horseshoe shaped tunnel 2 foot wide and 6 foot high at the <br /> crown. The outlet gate is controlled by a gate stem installed in a tower about 60 feet from the <br /> entrance to the tunnel. The top half of the tower, installed in 1949 when the dam was last <br /> enlarged, leans. The reservoir is operated so that water is not stored above the top half in the <br /> winter to reduce the problems with ice flow, this practice could preclude the reservoir from <br /> filling in dry years. <br /> The entrance to the tunnel is below the sediment level with water flowing vertically into the <br /> entrance rather than horizontally as originally installed. A trash rack is believed to be in place <br /> but could not be seen because of the silt. The existing gate is 2 foot wide and 3 feet high. The <br /> main problem with the operation, in addition to the leaning tower, is releases at low flows. The <br /> gate is too large to accurately control low flows. <br /> The recommended repair to the gate is to install a hydraulically controlled gate on the entrance to <br /> the outlet tunnel and remove the tower. In order to install the gate, the tunnel entrance would be <br /> excavated and exposed. The entrance to the tunnel would be extended and elevated so that the <br /> entrance would be above the silt. A new concrete structure would be constructed on the end of <br /> the tunnel that is the base for a hydraulically controlled 2 foot square gate and trash rack. A <br /> small gate, about 12 inches in diameter may also be considered for low flow releases; in this case <br /> there would be two hydraulically controlled outlet gates. The smaller gate is presently suggested <br /> as a design option and not included as part of this feasibility study. <br /> The concrete structure would be excavated deep enough for an adequate footing and would be <br /> extended upward about 10 feet to be above the silt. The structure would be designed based <br /> largely upon the requirements of the gate installation. See Figure 3 which shows a schematic of <br /> the structure. The hydraulic controls would be placed at the toe of the dam so that the gate can <br /> be operated at the measuring flume. The outlet works quantities and costs for the enlarged dam <br /> are included in Table 6 and for the existing dam in Table 7. <br /> 22 <br />