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I I I I I I I I I I I I I I I I I I I Repair of the leakage at the outlet gates and installation of the power plant are the two remaining components of the project. Figure 4.1 shows the dam in relation to the project facilities. 4.1 GATE REPAIR The irrigation releases from Lemon Dam are controlled by two pairs of outlet gates, with each pair capable of releasing 455 cfs. The non-irrigation releases are made through an existing 8-inch bypass pipe on which the turbine will be installed. Each pair of gates includes an emergency gate which is either opened or closed and a regulating gate that can be opened to various degrees to make the desired release. The seats on all four of the gates and frames have become pitted during the past 20 years of opera- tion and no longer close tightly. While the total leakage of 0.25 cfs is not considered so great that the dam is in jeopardy, the District is still required by Reclamation to make specific plans to repair the gates in the near future. The regulating gates can be repaired by closing the emergency gates; however, the only way the emergency gates can be repaired is to dewater the entire outlet works. The outlet works consist of an intake structure in the reservoir and a 900-foot long, 8- foot diameter pressurized tunnel between the intake and the gates, and a 900-foot unpressurized tunnel downstream of the gates to the river. The top of the intake structure is at elevation 8018 feet which means that it is normally covered by about 70 to 100 feet of water. The following two options exist with respect to dewatering the outlet works: (a) utilization of the 19-inch thick, 8. 5-foot diameter, 14,000-pound concrete plug which was builtin the intake struc- ture. The reliability and condition of this concrete plug is 4.0-2