Recent Dam Safety modifications to the Isabella Main and Auxiliary Dam were constructed to address actionable potential failure modes. Isabella Lake is located on the Kern River 34 miles upstream of the City of Bakersfield in Kern County, California. Isabella Dam was designated as a Dam Safety Action Class (DSAC) I project by the U.S. Army Corps of Engineers (USACE), and required action to reduce probabilities of failure and associated consequences. Isabella Dam construction began in 1948 and was completed in 1953; the project consists of two embankment dams that provide flood control, water supply, power generation and recreation benefits to the region. The modifications were required to address actionable potential failure modes identified over three primary areas of deficiency, including hydrologic overtopping, internal erosion of the foundation, and seismic instability from strong ground motion and/or fault rupture.
This presentation will highlight on the identified risks that were actionable for USACE and the risk process through design and construction. This will include highlighting the application of the Risk Informed Design process and adjustments made to the project. The presentation will cover the specific geologic, geotechnical, and hydrologic driven failure modes and the risk informed modifications to address them. Specific focus in the presentation will be made on the continuity of the risk process from the failure mode identification through adjustments in construction. Finally, the presentation will highlight steps in the USACE Post Implementation Evaluation (PIE) process to evaluate the risk reduction gained from the executed modifications; including, characterization, modification, and risk confirmation to address the hazards and potential risk.
