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<br />Louden Irrigating Canal & Reservoir Company <br />July 15,2008 <br />Page 4 of 6 <br /> <br />Agenda Item l6a <br /> <br />Four alternatives were considered: <br /> <br />No Action Alternative <br />The no action alternative was ruled out because even though the alternative has no immediate <br />capital expenditures, the risk and potential future costs can be very great. A problem with a slope <br />failure in the dam embankment during the height of the irrigation season could result in the loss of <br />the reservoir for the season. rfthe dam is not repaired, the Reservoir could become permanently <br />restricted to GH 10.0, thus resulting in the permanent loss ofthe 150 AF of water stored. <br /> <br />Selected Alternative No. 1 - Excavation and Re-compaction <br />Alternative 1 is the excavation of a core trench in the center of the dam in the affected area to a <br />depth of 17 feet below the dam crest and the re-compaction ofthe excavated material. This <br />alternative will cut off the seepage and add stability to the dam by removing and replacing the <br />poorly compacted material. The estimated total project cost for this alternative is $290,000. <br /> <br />Alternative No. 2 - Sheet Pile Wall <br />Alternative 2 is the placement of a steel sheet pile wall along the center of the dam embankment in <br />the affected area. The steel sheet pile wall is to extend from the crest of the dam down into bedrock. <br />The sheet pile wall will cut off the seepage in the zone where the wall is placed. However, it will <br />not add stability to the dam or prevent future settlement of the embankment. The estimated total <br />project cost for this alternative is $ 495,000. <br /> <br />Alternative No. 3 - Bentonite Slurry Trench <br />Alternative 3 is for the placement of a bentonite slurry trench along the center of the dam <br />embankment in the affected area. The bentonite slurry trench is to extend from the crest of the dam <br />down into bedrock. The seepage in the zone where the bentonite slurry trench is placed will be cut <br />off due to low hydraulic conductivity of the wall. The bentonite slurry trench will not add stability <br />to the dam or prevent future settlement of the embankment. The estimated total project cost for this <br />alternative is $ 375,000. <br /> <br />Alternative No. 1 is the selected alternative. Smith Geotechnical has prepared preliminary <br />engineering designs and cost estimates for this alternative. The cost estimate and proposed schedule <br />are as follows: <br /> <br />Project Cost Estimate <br /> <br />Engineering <br />Construction <br />20% Contingency <br />Total <br /> <br />$57,500 <br />$193,500 <br />$39,000 <br />$290,000 <br />