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<br />e <br /> <br />e <br /> <br />. <br /> <br />A toe drain is included to control seepage through the embankment. <br />The drain would probably be a sand filter (ASTM C-33 sand) with a <br />slotted drain pipe to convey water out of the filter. The drain is <br />estimated to be 5 feet deep, 2 feet wide and about 500 feet long. <br /> <br />The cost of a roller compacted concrete dam was roughly evaluated <br />and was significantly more costly but offered the advantage of a <br />spillway. If the cost assumption herein for a spillway is not <br />adequate, an RCC dam should be reconsidered. <br /> <br />OUTLET PIPE: The outlet pipe size is suggested to be 36 inch <br />diameter which is significantly larger than the size required by <br />the Rules and Regulations but provides easier operation and <br />maintenance and if a liner is needed in 50 years or so, it can be <br />installed without impacting the ability to drain the top 5 feet of <br />the reservoir in 5 days. The pipe material should be thick walled <br />steel, possibly lined with mortar or another material; CMF is not <br />reconunended. <br /> <br />SPILLWAY: The spillway will be sized to pass the PMF (probable <br />maximum flood). The PMF was estimated from Bureau of Reclamation <br />reconnaissance level sizing criteria, which indicate that the 20 <br />square mile drainage area would have a flood of about 14,000 cfs <br />and 4,000 acre-feet of volume. <br /> <br />The location of the spillway is a problem because the valley is <br />very narrow and the spillway cannot be placed on either abutment. <br />Therefore the spillway must be incorporated in the embankment <br />somehow, such as a chute on the downstream face of the dam or a <br />drop structure. A specific plan for the spillway is not included <br />but a large cost is included to allow various methods. <br /> <br />East Lake Creek Dam <br /> <br />7 <br />