C150361 Feasibility Study - Laserfiche WebLink

Home Browse Search

ID Number Administration Number Adjudication Date Decreed Amount 996 # 21263.20371 0 06/23/1914 90 Aft 1837 # 29260.23550 0 05/28/1937 235.9 AFt The water rights of Lone Cabin Ditch and Reservoir Company are normally considered adequate for the acres irrigated, except for the seepage losses in the canals and excessive losses due to flood irrigation practices. The drought year of 2012 resulted in water shortages that impacted the system in June. Dam History The Lone Cabin Dam was originally constructed in 1905 as a homogenous earth fill dam and was enlarged in 1907. According to the Engineer's Inspection Report (Appendix B), the dam was completed to the height of 36.5 feet in 1936. It was constructed 697 feet long with a crest width of 9.5 feet that includes a Forest Service road, and has a storage capacity of 163 acre- feet. Buckhorn Geotech performed a topographic survey of the dam and the slope failure on October 10, 2011. From that survey, a dam height of 52.6 feet, length of 754 feet, crest elevation of 7,391.58 feet, and slope of 2.6:1 (H:V) of the downslope embankment was measured. From these dimensions, it appears that there had been an additional rise in the dam height of 16.1 feet since 1936. The length of the crest, as a result of these modifications, also increased by 57 feet. The spillway elevation is 7,387.66 feet. According to files available at the Colorado Division of Water Resources Water Division 4 office, a June 27, 1961 report indicated a "small slip at the toe [of the dam] some time in past". No reports or photographs document a repair. Another document from 1973 indicated a "small slip [22 feet long] above spillway return pipe," but no records indicate when or how a repair was performed. According to Jason Ward, Dam Safety Engineer for Water Division 4 of the Colorado Division of Water Resources, the file for the Lone Cabin Dam contains photographs of a reported slump in August 1984 and another slump recorded on August 15, 1985. It appears on the photographs that the smaller slide from 1984 is located within a larger slide from 1985. The 1985 slump appeared to have a well-defined head scarp on the photographs and a storage restriction was applied. The 1984 to 1985 water year was record setting and included heavy summer thunderstorms, deep snowpack, and high spring snowmelt, all of which may have contributed to these slope failures. In an effort to repair these failures, Lambert &Associates was retained and performed laboratory tests on soils to be used as fill and a slope stability analysis using a wedge of this material on the embankment. As indicated in their December 18, 1985 report entitled, "Geotechnical Laboratory Study and Slope Stability Analysis,"they performed their testing and analysis on soil samples obtained by Leroy Black of Ute Engineering and Surveying. No drilling of the embankment or field geotechnical evaluation was performed for this analysis. The 1985 slump was described as 25 to 30 feet wide and progressed 80 feet upslope from the toe by the Lambert and Associates November 6, 1987 geotechnical report entitled, "Proposed Remedial Work for the Downstream Slope of the Lone Cabin Dam near Paonia, Colorado." This report evaluated the characteristics of proposed borrow material for the repair (downstream fill 14