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<br />'- <br /> <br />Young Creek Reservoir Company <br />September 14-15. 2004 <br /> <br />Agenda Item 4c <br /> <br />In 2001, a geotechnical investigation of the dam was completed, and paired piezometers were <br />placed within the embankment structure, to allow phreatic surface level monitoring and <br />determination of the hydrostatic pressure at the interface between the dam structure and slide rock. <br />However, since that time the reservoir has not filled, due to the last two years of drought, and it has <br />not been possible to utilize the piezomenter information. Over the past two years the reservoir has <br />never been more than 60% full, and some piezometers have never seen water. Therefore, <br />assessment of the dam's performance under full hydrostatic head has not been possible, and <br />several time extensions have been granted by the State Engineer's Office (SEa). <br /> <br />. <br /> <br />The latest SEa dam inspection was in August 2004. Currently the dam is not restricted, but is <br />approved for conditional full storage, pending monitoring and assessment that cannot occur until <br />the reservoir fills, along with continued efforts to permanently address the left abutment seepage <br />situation. YCRC desires to reduce the risk of future loss of functionality of the impoundment and <br />minimize the potential for restriction on the reservoir volume. The company is proposing to line the <br />reservoir along the left abutment as an initial solution to the most obvious structural deficiency. The <br />proposed liner project will address the immediate sinkhole problem, allow the reservoir to be filled <br />so that the piezometers can be monitored, and allow identification of the possible need for future <br />improvements to the dam. Depending on the outcome of the project, additional lining or drains <br />may need to be installed. SEa dam safety personnel are supportive of this approach. <br /> <br />Feasibility Studies <br /> <br />Smith Williams Consultants, Inc. of Denver has completed the feasibility study in accordance with . <br />CWCS guidelines. The study includes an assessment of alternatives to address the most critical <br />structural deficiency of the reservoir. <br /> <br />Youna Creek Reservoir Company <br /> <br />The YCRC is a Colorado non-profit corporation registered in the State of Colorado, established in <br />1897. There are 34 shareholders and 60 shares of stock. YCRC has the power to set annual <br />assessments, cut off water deliveries to shareholders that fail to pay their assessments, and to offer <br />stock for sale in order to pay back assessments. <br /> <br />Water Riahts <br /> <br />The source of water for YCRC is diversion flows out of the Young Creek drainage, a tributary to the <br />Forked Tongue drainage on Grand Mesa. Impoundment rights totaling approximately 781.92 acre- <br />feet in Young Creek Reservoir #1-2 and 230.46 acre-feet in Young Creek Reservoir #3 were <br />obtained through legal appropriation between the dates of 1907 and 1960. The total decreed <br />annual storage is 1012.38 acre-feet. <br /> <br />Proiect Description <br /> <br />The purpose of this project is to provide initial rehabilitation to Young Creek Reservoir # 1-2 for <br />mitigation of sinkholes that have historically occurred within the basin, and to minimize potential <br />damage to the reservoir that would limit its impoundment capacity. Four alternatives were <br />considered, for this initial project, as listed below: <br /> <br />1. The no-action alternative. <br />2. line the left abutment and reservoir area with 60 mil HDPE liner ($174,475). <br />3. Line the left abutment and reservoir area with geosynthetic clay liner ($180,440). <br />4. Line the left abutment and reservoir area with a compacted clay liner ($176,115). <br /> <br />. <br /> <br />Page 2 of 5 <br />