Albeni Falls Dam, a critical piece of U.S. Army Corps of Engineers (USACE), Seattle District, infrastructure on the Pend Oreille River, in Oldtown, Idaho, is undergoing vital repairs to its aging spillway gates, ensuring continued flood control, hydropower generation and recreational opportunities for years to come.
At the heart of this crucial rehabilitation effort for Gate 3, a technologically advanced material – Fiber-Reinforced Polymer (FRP) – is playing a pivotal role, offering a glimpse into the future of dam maintenance and a testament to modern engineering ingenuity.
“FRP is a proven technology that has been used in this type of environment before,” said Tony Fegert, chief of operations and maintenance at Albeni Falls Dam. “I see opportunity for this to be used extensively in the future.”
Discovered in April 2024 during routine maintenance, Gate 3, one of the dam's ten spillway gates (plus a spare), revealed defective steel, likely a consequence of the original 1950s fabrication process. This finding prompted USACE Seattle District to restrict gate operations to ensure safety and stability.
While a long-term plan for complete gate replacement is underway, with the first gate anticipated to arrive onsite in 2027, and expected subsequent gates arriving in 6-month intervals, the immediate need was for a robust, interim solution to bring Gate 3 back into service and restore the dam's full operational flexibility.
This is where FRP steps in, offering a technically superior Band-Aid that provides significant structural enhancement. As Seattle District Commander Col. Kathryn Sanborn mentioned in public meetings held May 1-2, 2025, Gate 3, having been removed for rehabilitation and defect assessment in 2024, was slated to return to Albeni Falls Dam in early May.
On its return onsite May 12, USACE began the FRP installation process (applying layers of fabric, adhesive and epoxy) the week of June 2, 2025, and will continue till the end of July 2025. The gate is projected to return to service in August 2025.
“Dam gates are subject to constant movement, vibrations and stress cycles,” said Albeni Falls Dam Operating Project Manager Amanda Smith. “FRP's composite nature provides excellent fatigue resistance, making the repair more resilient to the repeated stresses of opening and closing and the dynamic forces of flowing water. This translates to a more durable repair that can reliably perform its function until the full gate replacement program is complete.”
The Power of Composites in Action
FRP is not a single material but a class of high-performance composites, typically involving strong fibers like carbon or glass embedded in a durable polymer matrix. Imagine a sophisticated, super-strong fabric, bonded with a resilient resin, meticulously applied to the affected areas of the dam gate. This seemingly simple application underscores a profound engineering advantage.
Despite its light weight, FRP possesses an exceptional strength that can surpass steel on a strength-to-weight basis. This means the repair adds minimal extra load to the gate's existing mechanisms, while significantly strengthening its structural integrity against the immense hydrostatic pressures it will face.
“FRP was determined to be the fastest and most reliable way to strengthen the gate and allow us (Army Corps) to place the gate back in the spillway,” said Fegert, whose team will complete the FRP application.
Unlike the steel it reinforces, FRP is inherently resistant to corrosion, rust and the degrading effects of water exposure, eliminating the persistent maintenance challenges associated with traditional steel repairs, such as repainting and rust treatment, promising a longer, maintenance-free life for the repaired section.
FRP can be installed in various forms, including wraps and laminates, allowing engineers to precisely target the defective steel sections. This adaptability is crucial for the complex geometries of a dam gate. Additionally, FRP systems often cure rapidly, minimizing gate downtime and accelerating its return to service - a critical factor for a dam's operational continuity.
FRP installation is not new to USACE. Ensuring the team responsible for applying it is trained, is vital. Engineers from Seattle and Walla Walla Districts, the Inland Navigation Design Center Mandatory Center of Expertise (INDC) and Albeni Falls Dam operations staff attended a 3-day U.S. Army Engineer Research and Development Center (ERDC)-led certification course, April 8-10, 2025, on applying FRP to repair fatigue-induced cracks on steel structures, onsite.
The Army Corps’ INDC provides engineering, design, analysis and review services for studies, new locks, new navigation dams, major rehabilitation of existing inland navigation locks and dams, and significant inland navigation lock and dam operations and maintenance projects. ERDC, USACE’s premier research and development center, discovers, develops and delivers innovative solutions to challenges in military engineering, installations and operational environments, civil works, geospatial research, and engineering and engineered resilient systems.
Developed and delivered by ERDC's Lead Research Engineer Dr. Guillermo Riveros, the certification course provided the team with the foundation and hands-on guidance needed to apply the specific FRP system to be used to strengthen the fractured critical members of Gate 3’s upper leaf.
“The hands-on [sessions] really allowed us to experience all the slight nuances to applying the different types of materials that go into this system,” said Fegert, who performed a practice repair during the training.
The practical exercises also included attendees switching roles to get a comprehensive, well-rounded experience in cutting the different fabrics, mixing epoxy and adhesive, and applying the system to the steel, procedures the Gate 3 FRP installation process entails.
A Bridge to the Future
“Public safety is and remains our top priority,” said Smith. “Applying FRP to Gate 3 is a strategic move that allows the Army Corps the ability to maintain essential operations safely, while executing a comprehensive, long-term replacement plan at Albeni Falls Dam. By strengthening Gate 3 with advanced composites like FRP, we can continue managing water levels, generating hydropower and supporting Idaho’s ecological and recreational needs.”
This project also highlights a growing trend in infrastructure repair, where entities including USACE are pivoting to innovative materials like FRP to address the challenges inherent with aging infrastructure. As dams across the nation age, lessons learned and successes achieved with Gate 3 could pave the way for more widespread FRP adoption, ensuring the longevity and resilience of critical water management systems for generations to come.
Once fully back in service, the repaired Gate 3 will stand as a testament to how cutting-edge materials literally hold the foundations of our modern world together.