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The dam was completely rebuilt in 1928/1929, and the work was accepted and approved by the <br />State Engineer at that time. Various modifications have been made since that time, including <br />modification of the spillway, installation of a measuring weir, and replacement of the measuring <br />flume below the dam. <br />Project Description - Analysis of Alternatives & Selected Alternative <br />The objective of this project is to complete design and construction of repairs that are necessary to <br />improve the condition and extend the useful life of the structure. Project engineers, RJH Consultants, <br />Inc. performed the following services to thoroughly examine possible alternatives: <br />- Performed an inspection of the outlet works including intake structure, horseshoe concrete <br />tunnel, rockcut tunnels, concrete bulkhead, control valves, and 30- inch - diameter intake pipes. <br />- Performed a topographic survey of the dam cross section near the outlet works and key <br />points of the outlet works. <br />- Performed engineering analyses to identify conceptual -level sizes and configurations for each <br />alternative. <br />- Performed simplified hydraulic analyses to evaluate hydraulic conditions for each alternative. <br />- Prepared conceptual -level plans and sections for each alternative. <br />- Estimated a planning -level cost to construct the non - similar components of each alternative. <br />Existing Conditions <br />A hydraulic evaluation of the existing outlet works was made to estimate the capability for meeting <br />the SEO requirement for evacuating the top 5 feet of reservoir storage in 5 days. RJH found that the <br />existing outlet works can evacuate the top 5 feet of reservoir storage in under 2 days. Site visits <br />showed that the valves will not open greater than about 50 percent. The capacity of the existing <br />outlet works at the normal maximum pool Elevation 7984.35 is estimated to be 194 cfs. The <br />minimum capacity required to release the upper 5 feet of the reservoir within 5 days is estimated to <br />be about 53 cfs. <br />Wrights Reservoir is operated as an irrigation reservoir and the water elevation varies throughout <br />the year. The Capacity of the outlet works is reduced during times of low water. <br />The valves and stems are intact but have more than 50 turns of slack in the gear driven operators. <br />The limited operating range is most likely due to a lack of fully opening both valves on a routine <br />basis, which has resulted in corrosion and gaulding of the operators in the unused range. The steel <br />pipes were significantly corroded on both the interior and exterior of the pipe surfaces and <br />sounding of the pipes indicated that the wall thickness was diminished and minimal. There did not <br />appear to be any pipe joints. All concrete appeared in good condition and rockcut surfaces were <br />smooth but irregular in section and shape. The rock appeared sound. <br />Description of Alternatives <br />Three conceptual -level outlet works rehabilitation alternatives were developed. The developed <br />alternatives vary based on the flow control concept. Generally, the flow control concepts are <br />upstream control only at the intake structure, control on the midsection of dam as it is controlled <br />now, or a combination of both upstream and midsection flow control. <br />