GeoStabilization began work in January 2018 to address the widespread deterioration affecting Willow Creek Dam after more than a century of service. Previous repair efforts had focused on localized fixes, but the condition of the structure’s aging concrete facing and associated infrastructure required a comprehensive rehabilitation strategy. The project scope ultimately included restoring the dam’s upstream and downstream faces, reinforcing the tunnel entrances, and strengthening the crest of the structure to return the reservoir to safe operation.
Before new materials could be applied, crews prepared the existing concrete surface to ensure a reliable structural bond. The deteriorated areas of the dam’s 100-year-old concrete were scaled and cleaned to remove loose or degraded material. This preparation was critical to achieving the required pull-off bond strength between the original dam surface and the new structural facing that would be installed.
Once surface preparation was complete, GeoStabilization installed a fiber-reinforced shotcrete system across the dam’s upstream and downstream faces as well as along the crest. This high-strength concrete layer effectively encapsulated the aging concrete and underlying materials, creating a hardened protective shell that stabilizes the structure and shields it from ongoing environmental deterioration.
The solution also included shotcrete reinforcement of the outlet and access tunnel entrances, areas that had experienced significant wear from decades of operation and seasonal water drawdowns. By encapsulating these vulnerable sections, the rehabilitation eliminated pathways for further decay while improving the durability of the dam’s most critical structural elements.
To maximize performance, reinforcement fibers were incorporated directly into the concrete mix, improving crack resistance and enhancing the long-term strength of the new facing system. The result was a continuous protective layer that both strengthens the dam and protects it against future weathering.
The Willow Creek Dam site presented unique logistical challenges due to its remote location—approximately two hours from the nearest concrete plant. To maintain consistent material quality and proper curing characteristics, GeoStabilization deployed volumetric shotcrete trucks that allowed crews to precisely control mix proportions and curing rates on site.
In addition, GeoStabilization’s engineering team developed a custom concrete mix designed specifically for the project’s environmental conditions and bonding requirements. This tailored mixture ensured uniform strength and adhesion across the dam’s entire surface during the application process.
Limited-access areas around the inlet tunnels required specialized installation methods. Crews applied shotcrete while working from rope systems and manlifts, allowing them to safely reach areas that conventional construction equipment could not access.
By combining comprehensive surface preparation, fiber-reinforced concrete encapsulation, and innovative construction methods, GeoStabilization successfully restored the dam’s structural integrity without the need for costly replacement. The completed rehabilitation significantly strengthened the aging infrastructure and extended the dam’s service life by approximately 75 years, preserving a vital water resource for agriculture and recreation in the region.
This cost-effective rehabilitation approach not only restored the dam to safe operation but also demonstrated the value of targeted infrastructure renewal. Through a streamlined design-build process and specialized construction techniques, GeoStabilization delivered a durable solution that allowed Willow Creek Reservoir to reopen to the community while safeguarding the structure for decades to come.
