Isabella Reservoir, located forty miles northeast of Bakersfield, California, consists of an earth fill main dam and auxiliary dam across Kern River and Hot Springs Valley, respectively. The reservoir provides flood-risk management, irrigation and recreational benefits. The Isabella Lake Dam safety modification project addresses overtopping, seismic and seepage issues identified with Isabella Lake’s main and auxiliary dams to reduce the likelihood of dam failure. The project consists of raising both the main and auxiliary dams 16 ft to help minimize the risk of overtopping, adding filters and drainage to both dams to increase dam stability, improving the existing spillway, and building a new 300-foot-wide emergency spillway.
Sequoia is providing comprehensive quality control inspection and materials testing services to the General Contractor, FDSJV. The QC scope includes inspection and testing for the excavation of 2.95 million cy of earth and rock for a new emergency spillway; construction of a 28-foot-tall Labyrinth Weir using 56,000 cy of Structural Concrete; buttressing and raising the existing dam structures by 16 feet; improvement and enhancements of the Dam foundation; processing and placement of more than 2.3 million cy of zoned fill embankment; modifications to SR-155 to accommodate the increased dam height; site work and improvements to several adjacent recreational facilities and roadways.