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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />III. Preliminary Opinion of Probable Costs <br /> <br />A preliminary cost estimate was developed for both reservoir alternates using current <br />construction costs for the Colorado area. The estimate is divided into sections to identify costs <br />for modifying the Peterson Ditch, reservoir construction, land acquisition, and permitting costs. <br /> <br />A 20% contingency was used for items not identified in this estimate. A more refined cost <br />estimate at the preliminary design stage will allow better identification of project components <br />and a resulting reduction in the contingency item. The largest cost in construction for either <br />alternate will be the embankment for the dam. Approximately 750,000 c.y. of material will need <br />to be moved for the smaller reservoir. <br /> <br />The larger reservoir would require placing 1,300,000 cubic yards of material. This alternate <br />requires more clay material than may be physically available on the site if the same dam design <br />is used. It may be necessary to use an alternate dam section that would use sand and gravel <br />alluvium in the downstream shell of the embankment. This would require salvaging sufficient <br />clay to reline the bottom of the site, which will add additional cost to the project. The cost <br />estimate did increase the unit cost of the embankment material by about 40% to reflect these <br />costs. <br /> <br />The release structure from the Peterson Ditch would be a concrete headwall with low head <br />diversion gates. The structure would create adequate headwater for diversion into the reservoir <br />feeder pipeline. The structure between the Peterson Ditch and the reservoir would be a low head <br />gravity pipeline. A small energy control structure would be placed at the pipe outlet in the <br />reservoir floor. There are no provisions in this cost estimate for rehabilitating the Peterson Ditch <br />upstream of this project or the Peterson Ditch diversion structure on the South Platte River. <br /> <br />The reservoir outlet structure would consist of a low head slide control gate, a concrete inlet box <br />and a concrete encased steel pipeline under the dam embankment. This structure would be <br />located at the southeast corner of the reservoir. At the downstream toe of the dam, an energy <br />reducing baffle structure would be placed which would direct flows into the flood control <br />channel that runs along the north side of State Highway 138 east to the Town of Ovid. This <br />channel would be cleaned and improved to allow routing of flows through it to the South Platte <br />River. <br /> <br />An amortization schedule was compiled for the project on a 40-year payback period. Both <br />alternates were evaluated. The project capital cost for each alternate was amortized at 3% <br />interest. Estimates for annual costs were included for project maintenance, and project operating <br />costs such carriage charges for the Peterson Ditch. These annual costs were increased every ten <br />years to reflect possible inflation and changed conditions. The total annual cost for the project <br />was divided by the total storage capacity in acre-feet to obtain a $/afvalue of the proposed <br />projects. The cost estimates show that the proposed project could be constructed for a cost of <br />between $600 to $700 per acre-foot. Table 6A and 6B are the amortization schedules that were <br />developed for the assumptions stated. <br /> <br />16 <br />