C150104 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I · The pumping water level in the wells does not drop below 30' from the surface elevation of the wells. Based on field pump tests from Canfield Drilling. · A 24" High Density Polyethylene (HDPE) or equivalent (c=140) pipeline delivers the water to the reservoir site. The sizing needs to be large enough to keep the overall total dynamic head below 85 feet. · The reservoir normal high water surface elevation is below 3,570' msI. The wells will require the construction of a manifold and pipeline delivery system to be used for this project. Additional studies at the preliminary level should be done to determine if phasing the project with later construction of this connection would work technically as well as economically. This well system does offer one alternate to fill the final 500 acre-fed of storage in the reservoir once gravity diversions from the Peterson Ditch are no longer feasible. A second alternate for topping off the reservoir would be to install a new pumping station at the proposed Peterson release structure. These pumps would be low head and have a shorter pumping distance to the reservoir. This alternate should be explored further at the preliminary design stage to determine the flexibility that a forebay/pumping plant would bring at this location. Figure 2 illustrates the locations of the possible water supply soufCIes in regards to the proposed reservoir site. The delivery of water to the proposed reservoir can be accomplished through the combined use of the Peterson Ditch and the either the "Ovid Wells" or a pumpiing plant on the Peterson Ditch. Gravity diversions from the Peterson Ditch will be capable offiIIing approximately 1,700 acre-feet of the 2,230 acre-feet of total capacity, or roughly 75%. The "Ovid Wells" are capable of supplying water to the reservoir for topping it off, but the operation of the wells will be more costly than the diversions from the Peterson Ditch. A preliminary cost estimate, based on current power costs, indicate the pumping costs associated with using the "Ovid Wells" to fill the reservoir would cost approximately $7.50/acre-ft. C. Water Deliveries to the South Platte River The reservoir would release water to the South Platte River through two methods. The first option would be an existing open channel running from the Southeast comer of the reservoir, following the existing drainage slough back to the river. The second option would be accomplished by reversing the flow in the pumping pipeline from the GASP Ovid wells and allowing water to flow by gravity back to the river. The present capacity of the open channel and slough back to the river may not allow for aU releases to go back to the river. There is a culvert through the railroad that is probably under capacity. There would also be some chmmel grading improvements that would be required if the Ovid Well pipeline manifold was not constructed. There is adequate property to construct these improvements and it is technically feasible. The sizing will depend on final operational decisions made at the preliminary design phase. The release structure for the reservoir will be sized between a 50 to 60 cfs maximum capacity. This capacity was modeled with daily gage flow records at Julesberg. Some simplistic assumptions were made in the modeling with regard to flows available for diversion. It allowed the 2,000 acre-foot reservoir to actually regulate an average annual diversion ranging between 1,800 to 2,400 acre-feet depending on assumed operating conditions. This was basled on an all or nothing approach to releases. If the release capacity from the reservoir was not adequate to bring flows up to 120 cfs, then the reservoir was not operated. This approach could supplement flows at the State line on up to 6