C150063 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I I investigation in 1979 and determined that the dam and reservoir are hydrologically adequate with the existing spillway. Some form of outlet works was included with the original dam construction. In 1919, modifications to, or reconstruction of, the outlet works were made to extend the outlet length and increase the discharge capacity to 500 cfs, bringing the outlet works to its present configuration. Over the years, there have been a number of repairs and fixes to the outlet gates and conduits, but overall the outlet works have operated well and have not suffered any significant damages or failures. The outlet works consists of three cast-in-place concrete outlet conduits, a gatehouse with a gate and operator to control each conduit, and an outlet structure. Each outlet conduit is nominally 3.0-feet wide by 4.5-feet tall with semi-circular top, with two control gates on each c~mduit. The outlets were inspected by the State Engineer in 1998 and no critical conditions were identified by the State Engineer requiring repair. Piezometer readings, seepage measurements, and observation of the downstream slope and toe of the dam do not reveal any significant problems with reservoir seepage that would impact the safety of the dam. Deficiencies The primary problem with the dam is the deterioration of the upstream slope protection. The existing concrete slabs have deteriorated over time, and the Company has had to overlay a number of the slabs through the years. The tremendous wave action on the dam, along with the effects of freeze/thaw and the normal deterioration that WGuld. be expected with time has all contributed to the deterioration of the concrete facing. The concrefe slabs are cracked, exhibit holes in numerous, but small areas, are not provided with a drainage and/or filter material be~ween the concrete and earth embankment, many have no seepage cutoff at the toe, and overall exhibit a general 18