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Feasibilitc Shide <br />Farmers' High Line Canal and Reservoir Company <br />October 2010 <br />■ Replacement of the radial arm gates with slide gates <br />■ liistallation of erosion control at headgates and diversion daiil <br />■ Placement of structural concrete at the diversion dam <br />■ Modernization of the cai7al control system. <br />The serviceable life of the stnicture can be sigiuficantly extencled tlirough the iinplementation of the <br />outlined modifications. <br />The cost of impleinenting this alternative would be $1,005,000. <br />Alternative 3, Removal and Replacement of the Diversion Stn�cture <br />The tlurd alternative would involve a full replacement of the structure. The cost of implementing <br />this alternative would be $2,007,000. This alternative was ruled out because it would increase the <br />cost of the project significantly and would increase the time required to conduct the construction. <br />Van Bibber Siphon <br />The FHL Cana1 crosses underneath Van Bibber Creek in a cast-in-place concrete inverted siphon. <br />The siphon is located to the west of Mcli7tyre Street between West 56th Place and West 58th <br />Avenue in the City of Arvada, Colorado. The stn�cture consists of upstream transition walls that <br />converge into a divided rectangle approach. This approach has a downward sloping apron and <br />sidewalls that terminate at the headwall of a twin cell concrete box culvert (9-foot wide by 5-foot <br />tall). This box culvert portion of the inverted siphon is �46 feet long. At the end of the culvert there <br />is another headwall that begins ai7 undivided rectangiilar exit structure with side walls and an <br />upward sloping apron leading up to the invert of the canal. The concrete apron continues past the <br />exit stn�cture for another �10 feet. The structure ends with diverging downstream transition walls <br />that terminate into the Canal banlc. <br />The siphon is located near the begiiu7ing of the canal with oi�ly six active turnouts or augmentation <br />locations above the structure. This leaves ±43 active turnouts and augmentation stations <br />downstream of this structure. Considerii7g that the majority of the shareholders are downstrean� of <br />this structure, it is very important to the Canal operation that flow be able to cross Van Bibber <br />Creelc in this siphon. This structure is considered to be of high importance to the operation of the <br />FHL Canal. <br />This structure has sigi7ificant damage including surface erosion which has extended well beyond the <br />original concrete surface compromising stnicture components. Stn�ct�iral displacement, movement, <br />or collapse was not observed despite the significant erosive damage. We did not observe a <br />significant amount of soil loss or settlement around the structure. The integrity of the structure is <br />anticipated to continue to degrade, ai7d if the erosion of the concrete surfaces is allowed to continue <br />unchecked the sti degradation will lilcely accelerate. It may be possible to extend the life of <br />the existing structure by instituting repairs in the near fi�ture. <br />Because of the need for these repairs, tliree alternatives were evaluated. The alternatives evaluated <br />are as follows: <br />-6- <br />