Rehabilitation at Standley Lake

The Standley Lake Dam and Reservoir is an earth embankment with a height of 33.5m and a crest length of 2,012m. The structure was constructed in 1908 using soil from railroad trestles and "puddling" in a clay core on a foundation of weak expansive, and slickensided claystone bedrock. With these, the dam was plagued with slope failures from the beginning while the old pressurized outlet works experienced separation problems at the joints due to creep and sliding of the embankment and foundation. A US$32.5M renovation was carried out in 2002-2004 that included constructing outlet works tunnelled in the abutment, a new spillway, and placement of additional stability berms.