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<br />I <br />:1 <br />I <br /> <br />I <br />, I <br />I <br />I <br /> <br />, <br /> <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />. Upgrade Spillways. A concrete sUI should be added to the entrance of both the side <br />channel and emergency spillways to minimize erosion during times of flow. These sills <br />should be approximately 1 foot wide, 5 feet deep, and extend the full width of the <br />spillway to the embankment crest. Rip-rap erosion protection should be added <br />immediately downstream of the new sill on the emergency spillway. The dike forming <br />the left side of the emergency spillway channel should be removed and recompacted. <br /> <br />. Construct Drainage from Seepage Area. To minimize the effects of saturation at the <br />downstream toe, the seepage area at about Station 114 + 00 should be drained. Gravity <br />drainage should be provided by a buried drain. The remaining low area should be <br />filled. <br /> <br />. Upstream Slope Protection. Riprap slope protection should be placed on the remaining <br />portions of the upstream face of the main embankment. <br /> <br />5.5.1 SEEPAGE REDUCTION MEASURES <br /> <br />Methods of reducing the seepage at Hourglass Reservoir include various ways of providing a <br />barrier to seepage. Six options for reducing seepage were considered and are discussed below. <br />The options vary widely in the degree and certainty of seepage reduction. <br /> <br />1. Full Deoth Slurrv Wall. To be e1fective as a seepage reduction measure and to reduce <br />the high phreatic levels in the downstream portion of the embankment, a slurry wall <br />constructed through the embankment and into the foundation would need to tie into an <br />impervious stratum at its toe along its entire length. No such stratum was encountered <br />in the foundation soils in our test holes. Bedrock was not encountered in any of our <br />test holes, and the depth to bedrock at Hourglass Reservoir is unknown. For cost <br />estimating purposes, we have assumed that the depth to bedrock is approximately 200 <br />feet under the main portion of the embankment. In order to provide a complete cutoff, <br />a slurry wall would need to start at the right abutment near the emergency spillway, <br />pass through the dike and main embankment, and continue around the north and west <br />sides of the reservoir to tie back into the valley wall. <br /> <br />5-17 <br />