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<br />. <br /> <br />the point that water could not be diverted into the head gate. Relying on sand dam <br />construction would delay the need to constrUct a permanent dam, but a permanent dam <br />will probably need to be built at some time in the future, and at a greater cost. <br /> <br />. <br /> <br />5. Selected Alternative: <br />Alternative 3 was selected, It has the advantage of long term control of the river <br />channe~ plus a cost savings over alternative 2. Drawings of the proposed project are shown <br />in Figure 5.1 and Figure 5,2 on the following pages. <br />Dam Design: <br />The concrete dam section is twenty feet high from the top down to the base. <br />Approximately two to four feet will be above the groood leve~ and will provide the <br />diversion capability. The additional height of the dam will be below groood level. A ten <br />foot apron will control the flow of the water to the river bed below the dam, <br />The dam structure will be anchored by the use of either H pilings or railroad rails. <br />Pilings will be driven to bed rock. Railroad rails are frequently used for construction if <br />they can be fOood, They are generally cheaper, and structurally equivalent to other steel <br />pilings. The pilings will be located throughOl!t the dam at approximately six foot intervals, <br />and tied together with rebar, The rebar willlJe welded to the pilings, <br />The dam will be faced with steel sheet piling to protect the face of the dam from <br />wear due to the sediment carried by the river, <br />Head Gate Design: <br />The head gate will be designed to provide two functions. The first is to divert water <br />into the canal. The second function is to "sluice" out the sand which tends to accwnulate at <br />the entrance to the canal. The sluice gate will be an eight foot wide radial gate oriented at a <br />right angle to the flow of the canal. The gate into the canal will be a slide gate. Power to <br />operate the gates will be supplied by a power pack on the pickup truck of the ditch rider. <br />Electric motors would be preferable, but eleotricity is not available, In the final design <br />stage, the selection will be made between hydraulic motors or electric motors, <br />The concrete structure of the head g.'de will also be anchored, as the dam, with <br />pilings and faced with sheet steel. <br />Cost Estimate: <br />Details of the cost estimates are presented in Appendix H. Two methods were used <br />to estimate costs. <br />The first method was to estimate the materials and labor costs based on the selected <br />alternative. Costs of the project include engir1eering and design, concrete and fill material, <br />labor, equipment, stee~ and the cost of the rildial and slide gates. The project is expected to <br />take about two months to complete, The cost estimate using this method is $313,238. <br />The second method used was suggested by a contractor who has 15 years of <br />experience doing similar construction in the Arkansas valley. He estimates a job by <br />multiplying the cubic yards of concrete in a project by $400. The cost using this "rule of <br />thwnb" is $326,000. The two estimates are within 4% of each other, which is very close. <br /> <br />. <br /> <br />Method <br />Swn of Costs <br />"Rule of Thwnb" <br /> <br />Cost estimate <br />$313,238 <br />$326,500 <br /> <br />10 <br />