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<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 />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />. Left Groin Erosion Protection. To reduce the potential for erosion, a lined ditch should be <br />constructed along the left side of the downstream face of the main embankment, and the <br />grading modified to redirect surface runofl. <br /> <br />. Crest Regrading. To bring the crest of the embankment to a un~orm elevation and <br />continuous slope to the upstream side, the crest of the embankment should be regraded. <br /> <br />. Upgrade Spillways. A concrete sill 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 spillway <br />to the embankment crest. Rip-rap erosion protection should be added immediately <br />downstream of the new sill on the emergency spillway. The dike forming the left side of <br />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 shouid be drained. Gravity <br />drainage should be provided by a burled drain. The remaining low area should be 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 Death Slurrv Wall. To be effective as a seepage reduction measure and to reduce the <br />high phreatic levels in the downstream portion of the embankment, a slurry wall constructed <br />through the embankment and into the foundation would need to tie into an impervious <br />stratum at tts toe along Its entire length. No such stratum was encountered In the <br />foundation soils in our test holes. Bedrock was not encountered in any of our test holes, <br />and the depth to bedrock at Hourglass Reservoir Is unknown. For cost estimating <br />purposes, we have assumed that the depth to bedrock is approximately 200 feet under the <br /> <br />5-16 <br />