C150245 Feasibility Study - Laserfiche WebLink

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examined. This option was determined the least financially feasible due to the distance of the Canal to the site and lack of existing conveyance infrastructure. The chosen alternative is described more in depth below. Selected Alternative The project area is located in Larimer County immediately north of Harmony Road and spans approximately a mile both east and west of Interstate 25. It includes a reservoir located on the east side of Interstate 25 and the conveyance system which begins west of Interstate 25 and crosses under the interstate at the northwest corner of the reservoir. The existing site conditions and proposed project is described below. Reservoir The reservoir area was mined by Flatiron Companies for sand and gravel resources. Once the mining was complete the pit was lined with a clay liner. The completed reservoir received state certification as a lined water storage reservoir on February 4, 2004 (Appendix F's). Modifications were made to the building pad at the edge of the reservoir in 2006, however this (lid not impact the State's designation of the reservoir as a lined storage facility. The capacity of the completed reservoir is approximately 650 acre -feet. It has an average depth of 12 feet. Appendix F includes the surveyed reclamation exhibit. An inlet structure on the northwest corner of the reservoir will need to be constructed for a 30 cfs capacity to fill the reservoir. The 30 cfs capacity allows the Company to take full advantage of its water right. A 10 cfs pump station is proposed at the southeast corner of the reservoir. There is an existing pond and outlet in this location that was used by the gravel operation to discharge to the Poudre River. The proposed pump would pump water from the reservoir into the pond and the water would gravity flow to the river. Applegate Group met with the Army Corps of Engineers to determine if there were wetland concerns with this proposed project. A copy of their reply stating that they did not see any concerns is attached as Appendix G. Lateral System The existing ditch lateral system diverts water from the Boxelder Ditch approximately 2,000 feet west of I25 and carries it in a reconstructed ditch through Arapahoe Bend Natural Area, a Fort Collins open space property west of I -25. Water conveyed to the east and carried underneath I -25 in a 24 -inch corrugated metal pipe (CMP) culvert and discharged into another lateral ditch that would flow to a location near the northwest corner of Timnath Flatiron Reservoir. Topography was prepared from the reservoir upstream to the diversion on the Boxelder Ditch to determine if the 30 -cfs required flow could be delivered on this alignment. According to the survey by King Surveyors, approximately 3.33 -feet of fall is available in the approximately 2,400 -feet between the diversion structure and the end of the ditch lateral near the northwest corner of the reservoir. This implies that water can be delivered to the reservoir from the existing Boxelder Dutch, however the ditch will need improvements to carry a flow of 30 cfs. These improvements are part of this loan request. Diversion Structure A rectangular concrete lined ditch section with an 18 -inch diameter orifice and gate serves as the headgate on the Boxelder Ditch for the ditch lateral. Capacity of the existing, gated orifice is 0