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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 />I <br /> <br />001115 <br /> <br />economi cal, where the 1 eft abutment bench is lower and excavati on of the <br />spillway 1 ess. <br /> <br />Acceptabl e constructi on materi al s for an embankment dam were found in close <br />proximity to the axi s. Sand and gravel for the shell s and for concrete <br />aggregate is available in the river floodplain and from several terraces <br />occurri ng at di fferent el evati ons upstream of the dam, wi thi n the reservoi r. <br />The requi red excavati on of gravel and rock coul d be used in its enti rety as <br />shell material and riprap. Suitable impervious core material is located just <br />upstream and downstream of the damsite on the right side of the river. <br /> <br />No slope stability or reservoir penneability problems are expected with the <br />Powell Park Reservoir as it would be located wholly within gently rolling <br />terrain fonned by claystone and siltstone of the Wasatch Fonnation. <br /> <br />The cost estimates show Powell Park to be the third least expensive site <br />studied for the 50,000 acre-foot reservoir capacity, ranking behind the Warner <br />Poi nt and Canyon si tes by about 40 percent and 15 percent respecti vely. At <br />the 150,000 acre-foot capacity, Powell Park was 10 to 15 percent more than the <br />least expensive alternatives at Warner Point and Canyon. This is due to the <br />amount of excavation required for the side channel spillways. If the <br />centerline were moved downstream about 2.5 miles where the left abutment bench <br />occurs at a lower elevation relative to the valley floor, spillway costs would <br />be reduced and Powell Park woul d probably be comparabl e in cost to Warner <br />Point and Canyon. For the 300,000 acre-foot reservoir, Powell Park is 15 <br />percent less expensive than any of the alternatives at Warner Point or Canyon. <br /> <br />The Final Report concludes that the basic level of geotechnical infonnation <br />and data on potential damsites in the White River Basin has been significantly <br />advanced by this investigation, and that the primary study objectives were <br />accomplished. <br /> <br />The following represent the most significant overall conclusions of the study: <br /> <br />(A) Of the six damsites and associated storage reservoirs evaluated, <br />none can be eliminated from future consideration on the basis of <br />geol ogi c fatal fl aws. <br /> <br />E-12 <br />