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<br />" <br /> <br />, <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Town of Frederick - Mllavec Lake Rehabilitation <br />January 22-23, 2003 <br /> <br />Agenda Item 19b <br /> <br />maintenance. Therefore, the cost savings to the Town would be at least $42,000 per year per 100 <br />acres of Town property irrigated with raw water. <br /> <br />If the Town acquires additional water rights, the raw water irrigation system may also be used to <br />serve entities or customers in the future other than the Town. This would further enhance the <br />economic value of the project. Also, the proposed project will result in the reservoir capacity being <br />increased by approximately 275 acre-feet from an existing capacity of 775 acre-feet to post-project <br />capacity of 1,050 acre-feet. This increase in capacity, as well as the conversion to "lined storage", <br />will also increase the long-term value of the reservoir to the Town. The current project annual <br />demand of 450 acre-feet is less than the 60 percent of the 768 acre-feet total adjudicated storage <br />decree, and will be less than half of the total reservoir storage volume after the project. In the <br />future, Milavec Lake could also potentially serve as a secondary or "peaking" potable water source <br />to supplement CWCWD, <br /> <br />ProJect DescriDtlon <br /> <br />The September 2002 RMC Seepage Investigation Study evaluated three construction alternatives <br />for reducing seepage, including preliminary-level cost estimates for comparison purposes, The <br />alternatives were: <br /> <br />1, Partial Slurry Wall (1a) - $524,000 or Full Perimeter Slurry Wall (1b) - $674,000 <br />2. Partial Slope Liner (2a) - $728,000 or Full Perimeter Slope Liner (2b) - $$927,000 <br />3. Construction of Toe Drain Pumpback System - $120,000 <br /> <br />Alternative No.1: Would provide a hydraulic cut-off of the higher permeability sands underlying <br />the dam foundation by construction of a 20-23 foot (vertical) bentonite slurry wall, constructed inside <br />the reservoir about 20 feet from the upstream toe of the dam. <br /> <br />Alternative 1 a includes a slurry wall only along the north, east and south sides of the dam. <br />Alternative 1 b includes a slurry wall around the entire perimeter of the lake. . <br /> <br />Alternative No.2: Would provide a hydraulic cut-off of the higher permeability sands underlying the <br />dam foundation by construction of a 20-23 foot (vertical) compacted clay slope liner, constructed <br />inside the reservoir about 25 feet from the upstream toe of the dam (for construction and stability <br />purposes. ) <br /> <br />Alternative 2a includes a slope liner only along the north, east and south sides of the dam. <br />Alternative 2b includes a slope liner around the entire perimeter of the lake. <br /> <br />Alternative NO.3: Provides for construction of a deep toe drain gallery along the downstream <br />slope of a portion of the dam, where seepage water would be collected in manholes and pumped <br />back into the reservoir. <br /> <br />The selected alternative. Alternative 2b. Full SloDe Liner, was selected and approved by the <br />Town Board. The design proposes to extend a low permeability compacted clay slope liner from <br />the existing upstream clay liner down to the underling natural clay. The clay liner would tie into the <br />upstream face by construction a clay cap. Approximately 5,700 linear feet of liner with an average <br />depth of 20 feet would be constructed. Excavation for the clay liner, when hauled off-site will result <br />in 240,000 cubic yards of sandy material being removed and reservoir storage increased by 150 <br />acre-feet. In addition, geotechnical investigations indicated that the reservoir bottom consists <br /> <br />Page 3 of 6 <br />