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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 />a) Do nothing. <br />b) Breach Victor No.2 Dam and transfer flows to Bison Reservoir. <br />c) Abandon both reservoirs and construct a larger facility elsewhere. <br /> <br />Alternative "a" above is not acceptable in view of the City's need for water and <br />the state's restriction on the amount of water currently allowed to be stored. A <br />further cause for rejection is the need for stabil ization of the embankment to <br />provide a satisfactory factor of safety as outlined previously and in the accom- <br />panying geotechnical report in Appendix D. <br /> <br />Al ternative "b" above is not acceptable in view of the costs involved with <br />breaching the dam, restoring the reservoir site, constructing a suitable diversion <br />structure, constructing and maintaining the required diversion canal, upgrading <br />the Bison Reservoir dam embankment to accept the additional required storage, and <br />increasing the capacity of the Bison Reservoir outlet pipe. <br /> <br />Alternative "c" above was rejected because of the lack of a suitable site allowing <br />gravity flow, costs for land purchase, and costs for pumping including construction <br />of a new pipel ine to the City's treatment facil ity. <br /> <br />Preli.inary Design <br /> <br />A geotechnical report for the Victor No. 2 Dam has been prepared by Golder <br />Associates of Lakewood, Colorado. A copy of this report is included in Appendix <br />D to this report. According to the stability analysis from the geotechnical <br />investigation, the existing dam has a static factor of safety of 1.1 and a <br />seismic factor of safety of 0.9. Acceptable design standards fOr new construction <br />of damS call for a static factor of safety of 1.5 and a minimum factor of safety <br />under any condition, i.e. earthquake, of greater than one. Based on these <br />criteria a new embankment cross-section is required. Figure 5.7 presents a <br />cross-section of the proposed improvements to the embankment and Figure 5.8 <br />presents a plan view of the improvements. Based on the dimensions shown, the <br />proposed improvements will increase the static and seismic factors of safety to <br />1.75 and 1.39, respectively. The geotechnical report al so concludes that the <br />site is suitable for expansion of the dam and that sufficient quantities of <br /> <br />38 <br />