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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 />The dams for North Poudre Reservoirs 6 and 6 both have found several problems <br />or areas of concern that need to be addressed. Following Is a summary of the <br />deficiencies and the costs associated with the required repairs <br /> <br />RESERVOIR NO. 6 <br /> <br />1. Inadequate freeboard to allow filling to the maximum decreed gage <br />height. <br />2. Severely deteriorated outlet conduit and operator. <br />3. No emergency or service spillway. <br />4. Seepage problems on the main dam at the outlet ditch. <br />5. Inadequate to nonexistent upstream slope protection. <br />6. Locally oversteep face slopes In certain areas. <br />7. No energy dissipation structure. <br /> <br />The general overall condition of the embankments and their foundations Is good <br />with no serious problems. The .embankment and the foundation are composed <br />primarily of clays and weathered shales with the only sand layer found at a <br />depth of 30 feet below the dam embankment. <br /> <br />Four main alternatives were considered for the repair and rehabilitation of the <br />Reservoir No. 6 dams. Considering the problems noted above, the four alterna- <br />tives were developed to provide a range of choices and solutions to the problems <br />noted. Cost estimates were prepared for each alternative utilizing all existing <br />Information and the Information developed for this report. Following are the <br />estimated construction costs for the four "Alternatives" for Reservoir No.6. <br /> <br />RESERVOIR NO.6 - ALTERNATIVES <br />CONSTRUCTION COST ESTIMATE <br /> <br />Alternatl ve <br /> <br />Description <br /> <br />Es Uma ted <br /> <br />Cost <br /> <br />I. <br /> <br />Raise the dam to Gage Height 42.0', flatten <br />the upstream and downstream slopes to 3 to 1, <br />replace the outlet, provide a toe drain, <br />rip rap and bedding, and construct 350' wide rIprap <br />lined emergency spillway at the right abutment. <br /> <br />$ 999,025 <br /> <br />2. <br /> <br />Same as Alternative No. 1 except construct 350' <br />wide "Roller Compacted Concrete" spillway. <br /> <br />$ 962,725 <br /> <br />3. <br /> <br />Raise the dam to Gage Height 43.0', flatten <br />the upstream and downstream slopes to 3 to I, <br />replace the outlet, provide a toe drain, rlprap <br />and bedding, and construct 350' wide rlprap lined <br />emergency spillway at Gage height 37'at the right <br />abutment and a service spillway at Gage Height 36'. <br /> <br />$1 ,013,075 <br /> <br />4. <br /> <br />Same as Alternative No. 3 except construct 350' <br />wide "Roller Compacted Concrete" spill way. <br /> <br />$ 994,860 <br /> <br />II. <br />