Lettis Consultants International (LCI) served as the lead geologic consulting firm to the California Department of Water Resources (DWR) during the emergency response and reconstruction of the Oroville Dam spillways–one of the most high-profile dam safety projects in U.S. history.
Lettis Consultants International (LCI) served as the lead geologic consulting firm to the California Department of Water Resources (DWR) during the emergency response and reconstruction of the Oroville Dam spillways–one of the most high-profile dam safety projects in U.S. history. Following the 2017 spillway incident, LCI mobilized a team of over 30 geologists and 5 GIS specialists to provide geologic mapping, excavation monitoring, slope stability evaluation, and construction support throughout the recovery effort. Working closely with DWR, the U.S. Bureau of Reclamation, and the U.S. Army Corps of Engineers, LCI designed and executed a large-scale geologic and geotechnical site characterization program to support both emergency stabilization and long-term reconstruction planning.
This effort included:
- Logging over 150 boreholes totaling more than 10,000 feet of rock core
- Conducting seismic refraction and other geophysical surveys
- Installing and monitoring piezometers and inclinometers
- Performing detailed foundation mapping
- Synthesizing data from mapping and exploration into a comprehensive site characterization model
Precision Mapping with Drone and GIS Technologies
LCI’s team of GIS specialists played a key role in supporting geologic and engineering teams through drone-based remote sensing, orthophoto generation, and real-time GIS data integration. These tools enabled precise documentation and interpretation of over 50 acres of excavated and cleaned spillway foundations, mapped at high resolution (1:60 and 1:120 scales) within tight (3-day) time windows, directly supporting design and construction decisions without delaying construction.
LCI also supported the Independent Forensic Team by conducting targeted forensic investigations through the damaged spillway to better understand failure mechanisms insights that informed final design and regulatory review. Ensuring Safety, Quality, and Regulatory Compliance LCI collaborated with DWR to develop foundation preparation specifications and provided approval support for cleaned foundation surfaces prior to concrete placement. All work was completed under oversight from the Federal Energy Regulatory Commission (FERC) and the California Division of Safety of Dams (DSOD) to ensure adherence to the highest safety and quality standards.
With deep expertise in engineering geology, geologic mapping, emergency response, GIS integration, and construction-phase geological services, LCI helped ensure that Oroville’s rebuilt spillways were delivered safely, on time, and to a standard that protects downstream communities for generations.