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I I I I I I I I I I I I I I I I I I I 2.0 DAM INSPECTION 2.1 Genera 1 COr.1anche Dam and Reservoir was inspected on several occasions during the feasibility study and final design by various members of the MKE staff. The fi rst inspection was a si te reconnai ssance made on June 10, 1986, at whi ch time a Phase I inspection check list was filled out similar to the inspection form used by the State Engineer's Office. During the visit, the reservoir was near the restricted maximum level of elevation 9382 (G.H. 27.0). This report is included in Appendix A. The da~ was inspected again during the bore hole phase of the geotechnical investigation between August 25 and August 27, 1986. During this period the reservoir level was dropping rapidly from approxir.1ately elevation 9370 (G.H. 15.0) to elevation 9365 (G.H. 10.0). Finally, the dam and outlet works were inspected on September 22 and 23, 1986, and agai n bebreen October 12 and 14, 1987, at the tir.1e of the test pit excavations. The configuration of the existing dam and reservoir are shown in Dralti ngs 2024-Gl and G5. 2.2 Dam 2.2.1 Description Co~anche Dam is an earth embankment with a crest elevation of 9395, a maximum height of 40 feet, and a length of about 1500 feet. The dam was originally built in the early 1920's of slightly silty, sand and gravel borrowed fror.1 deposits of glacial till within the reservoir. The foundation is a glacial moraine composed of the sa~e sandy gravel till. Releases fro~ the reservoir are controlled by the Main outlet works that discharges into Beaver Creek and the Hourglass outlet works that feeds a canal leading to Hourglass Reservoir. A 100-foot wide riprap lined service spillway at elevation 9390 is located at the right abutment. The crest of the da~ for the 200 feet adjacent to the service spillway is at elevation 9394, one foot 10~/er than the remainder of the crest, and would serve as an auxiliary spillway. 2084H -2-