C150239 Feasibility Study - Laserfiche WebLink

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Project Description and Probable Costs Elements of the improvements described here have been developed in a series of work sessions with the GIC Board of Directors. Several aspects of the improvements are under continued discussion and final recommendations and detailed designs, when appropriate, will not be made until the engineering work is initiated following loan approval. Construction costs are estimated conservatively, in that a higher unit cost has been used when appropriate, and a contingency has been added based on the level of uncertainty with the particular improvement. River Diversion Improvements A key component of the anticipated improvements is the repair and partial replacement of GIC's diversion on the Cache la Poudre River. Photos of the diversion can be found in Figure El and E2 in Appendix E. The existing diversion structure shows signs of concrete deterioration, one of the three gates is stuck in a closed position, and the silt gate is not adequate. Last year, a crane had to be mobilized to the river diversion in order to remove a large tree trunk that was lodged on the upstream side of the structure. Several river diversion layout alternatives were considered and one of the concepts is shown in Figure 4. This concept was used in preparing a probable cost estimate which is shown in Table 3. The weir across the river is considered to be in reasonable condition except for some downstream foundation repairs that are needed. The original work was done with wood pilings and the anticipated repair will consist of removal of the pilings and pouring of a downstream concrete foundation wall. It is also anticipated that broken up concrete from the existing diversion structure can be used as riprap material. Highway 34 Structure Improvements The structure at Highway 34 needs improvements to create a suitable water surface level for gate deliveries while avoid the risk of overtopping. A solution to this problem has been conceptualized and probable construction costs developed for an actuated gate to control upstream water surface level. A long-crested weir is envisioned as well to allow excess flows to bypass the structure in the event of a gate failure. This structure has been conceptualized and is shown in Figure 5. Piping and Canal Lining Improvements Piping and lining of the canal is considered to be an improvement that could provide significant reduction of seepage and improve canal operations. Several alternative pipe materials are under consideration and piping is being compared to lining from the cost and longevity standpoints. Pipe materials selected for analysis were aluminized steel pipe, HDPE pipe, reinforced concrete pipe, PVC, and ductile iron pipe. The analysis of the different piping systems Aqua Engineering, Inc. Greeley Irrigation Company, Feasibility Study December 2006 - 5 -