PSE’s involvement in this project for the Oregon Department of Fish and Wildlife (ODFW) has extended for over a decade. It began in 1991 with the upgrading of a 30-year old fish ladder complex at Willamette Falls in West Linn, including the repair and upgrade of existing elements as well as the design of additional new structures. Following the floods of February 1996, the focus of the project expanded to inspect the damage to the fishway, study the potential for future flood damage and design for those anticipated conditions.
The investigation continued in 2009 when ODFW determined that additional damage had occured to the concrete structure and that an updated evaluation of the fishway was necessary. PSE entered into a competitive proposal process and was awarded the opportunity to lead the design team in the structural analysis and repair of the fishway.
The first phase of the project has involved field investigations and evaluation of the foundation to determine the cause of the damage. Portions of the fishway had experienced undermining, causing the structure to shift, joints to expand, and concrete to crack. It was recommended that emergency repairs be installed before the high water season to mitigate the risk of complete structural failure. After the temporary repairs were in place, instrumentation was installed to monitor the water levels and temperatures and any corresponding movement in the structure. The data collected will assist in the following phase of the project, which consists of the design for permanent repairs to the fishway.
