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<br />. <br /> <br />designed to carry the estimated lOO-year flow of 400 cfs, with a freeboard of at least 0.5 <br />feet. <br /> <br />Description of Recommended Proiect Plan <br />The Colorado Water Conservation Board recommends that an overflow channel be <br />constructed across the top of the tailings pile, stabilization measures be implemented on <br />the downstream face of the tailings pile to create an overflow spillway, and debris <br />removal be performed between the tailings pile and the upstream flume on West Willow <br />Creek. <br /> <br />The typical overflow channel cross-section is presented on figure 1. The cost estimate for <br />the recommended plan is presented in table 1. The recommended project plan consists of <br />the following key features: <br /> <br />. <br /> <br />1. A concrete trapezoidal overflow channel across the top of the tailings pile: <br />. Bottom width = 4 feet <br />· Side Slopes = 2H: 1 V <br />. Depth = 3.5 feet <br />. Slope = 0.01 ftlft <br />· Assumed Length = 100 feet (Actual length to be determined at final design based <br />on field survey) <br />· Minimum concrete thickness = 4 inches <br /> <br />2. Stabilization of the downstream face of the tailings pile to create an overflow spillway: <br />· Provided stabilization below the overflow channel by grouting or other <br />appropriate methods. <br /> <br />3. Debris removal between the tailings pile and the upstream flume: <br />· Remove all loose timber cribbing and excess debris from the open channel to help <br />prevent clogging of the steel pipe during high flows. <br /> <br />VI. SURVEYS, MAPPING, AND FINAL ENGINEERING DESIGN <br /> <br />Prior to construction of the recommended plan, the project site will have to be surveyed <br />and topographic mapping will have to be produced. That information will then be used <br />by the design engineer to produce the final design drawings and specifications for the <br />project. Once project funding is secured, the CWCB will provide contracting assistance <br />to the Town of CreedeIMineral County for the required surveying, mapping, and <br />engineering services. In addition, the CWCB will be available to review the mapping and <br />engineering products, and will assist the Town/County with securing an appropriate <br />construction contractor and construction inspectoL <br /> <br />. <br /> <br />4 <br />