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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 />. <br /> <br />. <br /> <br />INTRODUCTION <br /> <br />This proposal describes the engineering work necessary to <br />address the dam safety deficiencies at Sheriff Reservoir, <br />which have been identified by the U.S. Army Corps of Engineers <br />(COE) and the Colorado State Engineer's Office (SEO) and to <br />prepare a feasibility report for submission to the Colorado <br />Water Conservation Board (CWCB). We have based our recom- <br />mended scope of work and cost estimate on information obtained <br />from Mr. Greg Hammer of the SEO, our review of information on <br />file at the SEO, a site visit by Mr. Keith Ferguson of our <br />office on July 10, 1986, discussions with Mr. Charles Wisecup <br />of the Town of Oak Creek, our review of guidelines for pre- <br />paring feasibility study reports for the CWCB, and our <br />experience with similar types of projects. We have outlined a <br />three-phase program. Each phase of the work will terminate at <br />discrete decision points. It should be noted that costs are <br />given for Phase I and Task 1 of Phase II only, as the specific <br />contract with the CWCB and the Town of Oak Creek will cover <br />this work only. The remaining work phases are described for <br />planning purposes only. If it is determined during the Phase <br />1 work that no modifications are required to the Sheriff <br />Reservoir spillway, our work will be concluded and our fees <br />will be modified, as outlined in the Cost Estimate Section. <br /> <br />STATEMENT OF PROBLEM <br /> <br />The National Dam Inspection Act of 1972 (Public Law <br />92-367) authorized the COE to conduct inspections of non- <br />federal dams throughout the United States. As part of this <br />effort, the COE contracted with Charles T. Main Co. to <br />complete a Phase I inspection and evaluation of Sheriff <br />Reservoir. The Charles T. Main study was completed in <br />September 1980. As part of this study, the reservoir spillway <br />capacity was evaluated. Because the dam hazard classification <br />is "high", the dam is required to pass the inflow from the <br />probable maximum flood (PMF) in the 12.2-square-mile catchment <br />upstream of the dam. Note that the "high" hazard classifica- <br />tion is not related to the condition of the dam, but to the <br />presence of valuable property and human occupation downstream. <br />The Charles T. Main study showed that the existing spillway <br />could not safely pass this magnitude flood without overtopping <br />the embankment dam, which would likely result in dam failure <br />and the release of the water stored behind the dam. As a <br />result of this study, the COE put the dam and reservoir on a <br />national list of unsafe dams. <br /> <br />In addition to supervising the efforts to inventory and <br />evaluate dams throughout the U.S., the COE, as part of the <br />National Dam Safety Act, has worked with all state governments <br />to enact dam safety legislation and to implement dam safety <br />programs. Following creation of the national unsafe dams <br />list, the COE has continued efforts to get the states to have <br />dam owners complete additional studies, designs and construc- <br />