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I I I I I I I I I I I . I I I I I I I I. and collector pipe will be installed to collect and transmit seepage to a central location where it can be properly monitored. The abutment contacts with the raised embankment will be excavated to a suitable foundation surface, cleaned, and properly treated il1l11ediately prior to placing earthfill. Drain material will be placed between the raised portion of the dam and the abutments to control and collect the continuing seepage, and transmit it to the toe drain system. It is anticipated that the materials encountered in the auxiliary spillway excavation will be acceptable for use in raising the dam. Processed filter and drain materials are expected to be obtained from local commerical sand and grave 1 pi ts. Topsoil stri pped from the downstream face of the dam, foundation, and auxiliary spillway area will be stockpiled and reused following construction. Upstream slope protection on the raised dam will be provided by riprap obtai ned from an off -s i te source. The downstream face will be reseeded to establish a thick grass cover for slope protection. The existing embankment dam and proposed modifications are shown in Figure V.5. Existing Spillway The horseshoe-shaped crest of the existing spillway will be raised five feet to elevation 6370 by demolishing a portion of the existing concrete, exposing and extending the reinforcing steel, and reforming the overflow ogee crest with concrete. The sidewalls of the spillway chute will be raised in a similar manner. The existing bridge which spans the spillway chute at the dam crest will be left in place to provide structural support to the spillway. A new concrete bridge will be constructed across the top of the raised spillway walls to provide access. Studies have been performed which show the existing bridge, if left in place, would not be an obstruction to flow in the spillway. - 46 -