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<br />Chapter I - Introduction <br /> <br />On August 10, 2002, the 24-inch corrugated metal outlet pipe failed and caused the <br />development of a 15-foot in diameter by 20-foot deep sinkhole in the downstream face ofthe dam. <br />The owner, Lake Arrowhead Water Association, then drained the reservoir for safety reasons. The <br />stored water is used for irrigation purposes. The Company relies solely on Lake Arrowhead <br />Reservoir to store water for their shareholders. The SEO has the ability to require the dam to be <br />breached if the outlet and embankment are not rehabilitated to state dam safety standards. <br /> <br />The purpose of this feasibility study is to select a financially sound alternative to rehabilitate <br />Lake Arrowhead Dam, which will enable the Company to deliver their full water decree in a safe and <br />expeditious manner to meet member's present and future water requirements. This study is based, in <br />part, on the CWCB Board memorandum prepared by Mr. John Van Sciver dated September 18, <br />2002. A copy of the memorandum is presented in Appendix A. <br /> <br />Lake Arrowhead Dam is located in Weld County on Ashcroft Draw, a tributary to the South <br />Platte River, as shown in Figure I-I. The dam is located on the southwest corner of Weld County <br />Road 54 and 4th Avenue, 2 miles southwest of Greeley. The reservoir is filled from precipitation, <br />surface water, and groundwater inflow, and then pumped from the reservoir for mainly irrigation <br />purposes but also for fire protection, recreation, piscatorial, and wildlife purposes based on the filed <br />water rights. <br /> <br />Several dam rehabilitation alternatives were developed, which address the failed outlet pipe; <br />and embankment seepage control and monitoring through the use of a toe drain system. The outlet <br />pipe alternatives are classified in two categories: 1) structural and 2) non-structural. Three outlet <br />alternatives were considered in the structural category and one for the non-structural alternative. One <br />alternative was developed for controlling and monitoring the seepage from the toe of the <br />embankment. The Company is applying for 75 percent of the project cost through the CWCB Small <br />Project Loan Program and will be financing the remaining 25 percent ofthe construction cost with <br />contributing funds from member participation. <br /> <br />Lake Arrowhead Dam Rehabilitation Feasibility Study <br /> <br />1 <br /> <br />13DVLE <br />