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Ms. Minerva Lee <br />October 16,2013 <br />Page 3 <br />Figure 5 shows the downstream face of the gravity dam section in the lower photograph. Much <br />of the gunite facing has been lost. The small upper level outlet gate may be inoperable. <br />PROPOSED REPAIR <br />We have divided the repair project into two phases. Phase 1 essential work is that required to <br />make the dam and diversion structure operational for next spring's irrigation season. Phase 2 <br />work includes additional warm weather repairs that should be performed during the fall of 2014. <br />Phase 1 <br />Phase 1 repairs include the following items: <br />1. Rebuild crest utilizing masonry block and concrete <br />2. Rebuild left abutment buttress <br />3. Repair hole on left abutment <br />The proposed crest repair is shown on Figure 6. The repair consists of rebuilding the <br />downstream face utilizing matching quartzite blocks. This will retain the historic appearance of <br />the structure, as well as provide a durable downstream face. The blocks will also provide a <br />forming base for the remaining concrete placements. <br />The remainder of the crest will be built using cast-in-place concrete. This includes a mass <br />concrete block with a reinforced concrete upstream face wall and crest cap. <br />The left abutment buttress thrust block needs to be reconstructed. Additional inspection is <br />required once all trash is removed. It could require demolition of some or all of the existing <br />concrete buttress and rebuilding with reinforced concrete. Alternatively, it may be repaired <br />utilizing shotcrete, placement of rock anchors, and grouting. <br />The purpose of the above repairs is to restore the full arching action of the top eight feet of the <br />dam. This zone has loosened due to topography, freeze/thaw, and ultimately flood overtopping. <br />The hole in the downstream left rock abutment contact should be filled with reinforced shotcrete <br />and then grouted. Further inspection will allow us to evaluate if this repair is critical for <br />operation or can be moved into next year's Phase 2 work. <br />Phase 2 <br />We recommend repointing of masonry blocks on the downstream dam face. Small drain pipes <br />will be installed in the mortar joints to continue to allow drainage to occur. Special care is <br />needed along the rock/masonry contact.