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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 />Seepaoe <br /> <br />Seepage analyses were conducted for a representative cross-section from Drury <br />Reservoir. The cross-section extends across the reservoir bottom and upstream <br />of the high end of the reservoir and downstream of the dam. The cross-section <br />represents a 1-foot wide strip of the reservoir. Results from the analyses were <br />multiplied by the 4000-foot width of the reservoir to determine the total amount of <br />seepage from the reservoir. <br /> <br />Two analyses were conducted to approximate the amount of seepage out of the <br />reservoir. The first analysis used permeability ranges determined from the soils <br />sampled from the site. This analysis assumes that the entire reservoir bottom <br />consists of materials similar to those sampled in the geotechnical investigation. <br />In reality, the reservoir bottom could be highly variable. Based on this model, if <br />all of the materials under the reservoir were similar to those encountered in the <br />borings, approximately 0.02 to 0.2 ac-ft/day would seep into the ground. The <br />second analysis used higher material permeabilities and assumed that a coarse <br />sand and gravel layer exists 10 feet below the surface. Based on this seepage <br />model, approximately 1.3 ac-ft/day would seep into the ground. If undiscovered <br />gravel layers exist at shallow depths in the reservoir, the seepage rates through <br />the gravel could be significantly higher than those modeled. The results of the <br />seepage analysis are summarized in Table 4 and are shown in Figures 11 and <br />12. <br /> <br />Depth <br />0' - 10' <br />10' - 20' <br />20' - 30' <br />Total Seepa e <br /> <br /> <br />Geotechnical Evaluation Summary <br /> <br />Based on subsurface investigation, testing, and analysis, the site appears <br />suitable for the construction of the proposed reservoirs. The on-site materials <br />appear adequate for the construction of dams. A complete report of the <br />geotechnical investigation is contained in Appendix C. <br /> <br />Geologic Evaluation <br /> <br />A preliminary geologic assessment was made for the proposed sites using the <br />Geologic Map of Colorado compiled by Ogden Tweto. The Laramie Formation <br />consisting of shale, claystone, and sandstone of the Upper Cretaceous Age is <br />the primary geologic formation in the area. Surface layers contain some Eolian <br />Deposits of the Quaternary Age including silt and Peorian Loess. Based on a <br /> <br />New Cache Feasibility Study <br /> <br />18 <br />