C150319 Feasibility Study - Laserfiche WebLink

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Preferred Alternative and Cost Opinions The preferred alternative for all projects is one that the Fisher believes addresses the underlying infrastructure or maintenance concern while provid ing the most value to the ditch company. Cost opinions for the preferred alternatives for each project are summarized in Table 6. Preferred Alternative – Project 1. Rehabilitate Diversion Headgate . The preferred alternative would be to remove the corroded portions of t he existing gate and to repair those elements in kind (Figure 3). It is believed that the lower quar ter-to-third of the gate skin would be replaced with 3/8-inch steel. Additionally, structural members would be replaced if required, based on inspection in a shop environment. The in-situ inspection completed to date shows the upper portion of the gate skin, structural support, and hoist mechanism to be in good repair and serviceable into the future. Preferred Alternative – Project 2. Replacement of Existing pipeline along Broadway . The preferred alternative for this project would be to replace the existing corrugated metal pipeline with a 24-inch by 38-inch elliptical reinforced co ncrete pipeline (RCPE) (Figure 4). Though more expensive, replacing the existing pipeline at the current grade with RCPE will allow the pipeline to better resist the occasional loads applied to it and allow currently effective maintenance to continue. Further, it is believed that this pipeli ne will provide a long-term resolution to the pipeline issue, which will avoid the difficu lties associated with construction on a busy state highway right- of-way. Preferred Alternative – Project 3. Provide a sand-out structure downstream of Clear Creek diversion. A sand-out structure consisting of a 48-inch outlet to Clear Creek, a new slide gate and headwall, and a new check gate at the existi ng 72-inch diameter CMP path crossing would be provided to bypass sediment and debris from the Fisher Ditch to Clear Creek under the preferred alternat ive (Figure 3). It is anticipated that t he proposed project will require the removal of vegetation on the Clear Creek bank, in addition to requiring consultation with the U.S. Army Corps of Engineers (USACOE). Fisher Ditch be lieves that the new sand-out structure would enhance ditch operations and maintenance while causing a minimal impact to Clear Creek and the surrounding park area. Preferred Alternative – Project 4. Ditc h piping upstream of Federal Boulevard. A 1,500-foot long, 48-inch diameter pipeling, including an inlet headwall and trash rack, clean-out manholes at 400- foot intervals, and an outlet transition/clean-out to the existing reinforced concrete box culvert under Federal Boulevard would be constructed as a pa rt of this project (Figure 5). This project would allow Fisher deliveries to transit through the heavy dumping area without collecting debris, minimizing future maintenance costs and adverse water quality impacts, and would be a significant benefit to the shareholders of the ditch. 10