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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 />5.5 <br /> <br />REHABILITATION ALTERNATIVES <br /> <br />Rehabilitation alternatives fall into two general categories: items which need to be performed <br />to upgrade the overall condition of the embankment, and methods for improving the seepage <br />conditions. Rehabilitation measures recommended to upgrade the overall condition of the <br />embankment are shown on Figure 12 and summarized below. <br /> <br />. Seepage Collection. To minimize its detrimental effects, seepage which is currently <br />passing beneath the dike and main embankment should be collected in a filter drain. <br />This filter drain would be constructed along the downstream tow of the embankment <br />and along the discharge channel downstream from the existing energy dissipator. A toe <br />drain would be constructed along the dike in a trench approximately 4 feet deep <br />underneath the existing downstream toe. The area around the pipe and in the trench <br />would be backfilled with drainage sand. <br /> <br />A filter drain would be constructed in the area where seepage is exiting in the discharge <br />channel. This would be constructed by extending the outlet works approximately 70 feet <br />in the downstream direction. The downstream slope would be cut back to the original <br />2:1 (horizontal:vertical) slope, a new blanket and chimney filler drain constructed on the <br />bottom and sides of the excavation, and embankment material placed to flatten the <br />downstream slope to 6:1 and thereby cover the extended outlet works. This <br />construction would include demolition of the existing energy dissipator, and construction <br />of a new energy dissipator and riprap-lined stilling basin. <br /> <br />. Left Groin Erosion Protection. To reduce the potential for erosion, a lined ditch should <br />be constructed along the left side of the downstream face of the main embankment, and <br />the grading modified to redirect surface runoff. <br /> <br />. Crest Regrading. To bring the crest of the embankment to a uniform elevation and <br />continuous slope to the upstream side, the crest of the embankment should be <br />regraded. <br /> <br />5-16 <br />