Los Vaqueros Dam

Brentwood, California

Located in the northern end of the Diablo Mountain Range approximately 40 miles from San Francisco, the Los Vaqueros Dam serves as the primary water source for the Contra Costa Water District. Kiewit provided construction services for this $63 million, 192-foot-high dam. Completed in 1998, the dam measures 1,000 feet across its crest. The scope of work involved construction of 550 feet of reinforced concrete spillway, intake and outlet works, and a 1,300-foot-long, 84-inch-diameter concrete and steel-lined bypass tunnel. Work included a 2.5-mile access road; five 84-inch hydraulic gates on the intake structure; SCADA telemetry; and six rows of blanket and curtain grouting on the dam’s base.

Concurrent with the start of construction were delineation efforts regarding environmentally sensitive areas. Environmental awareness was given high priority due to several endangered and threatened species residing near the project site.

Major quantities were 2.8 million cubic yards of embankment, which included 300,000 tons of chimney-drain and filter-zone materials; more than 5.5 million cubic yards of excavation; and more than 1 million cubic yards of blasted sandstone. Specifications called for imported rip rap, however, Kiewit personnel suggested a value engineering concept that considered the creation of rip rap from on-site oversized rock encountered during excavation. As such, more than 50,000 cubic yards of rip rap was generated on-site.