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Feasibilitc Shide <br />Farmers' High Line Canal and Reservoir Company <br />October 2010 <br />l. No Action <br />2. Select removal of potentially hazardous trees ($126,000) <br />Alternative 1_ No Action <br />Tlus alternative was not selectecl because inaction would eventually result in the ditch losing <br />serviceability or could result in nearby structures being dainaged. <br />Alternative 2_ select removal of �otentiallv hazardous trees <br />This would involve a removing the trees that could threaten the either ditch capacity or nearby <br />stn�ctures. The cost of this alternative is $126,000. <br />SELECTED ALTERNATIVES <br />Club Crest Storm Drain Crossin� <br />Replacement of the culvert occurred from January to August 2010. This involved excavating and <br />removing the existing culvert. The cost of tlus alternative was $66,500. Constniction plans for the <br />replacement can be found in Appendix B-1. <br />Headworks <br />Replacement of the existing radial arm gates with slide gates and structural resurfacing of the <br />concrete walls on the front of the structures is recommended. The concrete resurfacing will <br />iinprove erocled surfaces and fill existing cracics and provide a new surface to mount the new gates <br />to. The slide gates will be equipped with electric actuators and modernized with installation of <br />SCADA systems. <br />The installation of erosion coi7trol to the inlet of the headgate and river gate structures, as well as <br />the downstream side of the headgate stn�cture is also recommended. Concrete slabs can be added to <br />protect the area from erosion. The concrete slabs will be poured with cutoff walls to prevent <br />seepage from undermiiung the structure. There are a few areas around the headgate and river gate <br />structures that have visible erosion around the walls and foundation. The walls have a small amount <br />craclang and they appear to show signs of settleinent. <br />To protect the existing diversion dam from undermiiung due to downstream erosion of the river <br />bed, the following inodifications are recoinmended: construct a sheet pile cutoff wall, extend the <br />concrete apron �10 feet downstream and tie into the proposed cutoff wall, and install grouted and <br />ungrouted riprap revetment downstream an additional 40 feet across the width of the channel. The <br />proposed erosion protection will repair existing dainage and provide protection downstream of the <br />dam for another 50 feet. The exact limits for the protection required will be determined by <br />modeling the flows over the dam in the desigi7 phase. <br />To repair concrete erosion at the existing diversion dam, structural concrete resurfacing is proposed. <br />Tlus will involve installation of concrete with reinforcing steel to cover the existing surface and <br />-10- <br />