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<br />. <br /> <br />would be incurred for care of water during the outlet works repair <br />and for 'construction of an access road to the dam toe. <br />The opinion of probable construction cost for Alternate B is <br />shown in Table 12. The total cost for Alternate B would be about <br />$1,040,000 including engineering, contingencies, and cost escalation to <br />1983. The cost for outlet works repair, access road construction, <br />and the monitoring program would be about the same as in Alternate A. <br />The major cost included in Alternate B would be related to construc- <br />tion of the dam enlargement and protection of the dam toe. <br />Consideration was given to the use of reinforced earth along the <br />existing dam crest. A six foot high reinforced earth crest would <br />allow the one-half probable maximum flood to be contained at a sub- <br />stantially lower cost. However, the additional weight on the exist- <br />ing dam crest could result in instability problems along the down- <br />stream face of the dam. Since there is uncertainty about the geotech- <br />nical feasibility of using reinforced earth, it is our opinion that <br />the higher costs of dam enlargement should be used for planning <br />purposes. Prior to final design of the dam enlargement, analysis of <br />information gathered through the dam monitoring program should indi- <br />cate whether reinforced earth can be used. <br />A cost estimate was made to determine whether spillway enlarge- <br />ment would be more economical than the dam enlargement for Alternate <br />B. The required spillway would be similar to the spillway enlargement <br />under Alternate C. Costs for spillway excavation and concrete place- <br />ment would increase total construction costs to about $3,800,000. <br />Therefore, it is recommended that the spillway should not be modified <br />under Alternate B. <br />The opinion of probable construction cost for Alternate C is <br />shown in Table 13. The total cost for Alternate C would be about <br />$5,590,000, including engineering, contingencies, and cost escalation <br />to 1983. Over half of the total cost would be related to installation <br />of the concrete floor and walls for the spillway. The concrete unit <br />cost was estimated to be $525 per cubic yard plus future cost escala- <br /> <br />. <br /> <br />tion. <br /> <br />. <br /> <br />-52- <br />