Tiger Creek Gates

Tiger Creek Afterbay Dam, originally constructed in 1931, stands approximately 120 feet tall and 400 feet wide. It features ten spillways equipped with steel Tainter gates and is owned and operated by Pacific Gas and Electric (PG&E). BDI had previously performed pin friction testing on these gates in 2015, and returned in 2024 to reassess trunnion friction and overall gate performance following PG&E’s trunnion greasing maintenance.

Each gate was instrumented using BDI’s custom-built strain transducers and rotation sensors. To evaluate hoist force, strain and torque sensors were also installed on the hoist chain and shaft. Data collection was performed using BDI’s Structural Testing System (STS) hardware and software. To access hard-to-reach components, BDI’s SPRAT-certified technicians and engineers employed rope access techniques, ensuring safe and efficient instrumentation across all ten gates.

After testing, BDI engineers calculated the maximum effective trunnion friction coefficients for each gate and compared them to the 2015 results. Most gate pins showed improved performance and had friction coefficients within the expected range. However, some pins exhibited increased friction or values exceeding expectations, suggesting potential alignment issues that warrant further investigation.