Priest Rapids and Wanapum Dam Safety Engineering Services

Grant County Public Utility District (GCPUD) operates the Wanapum and Priest Rapids Dams, two hydroelectric structures on the Columbia River. As the dam owner, GCPUD needed to meet rigorous Federal Energy Regulatory Commission (FERC) standards and ensure long-term performance. This required expert support to evaluate dam safety across structural, geotechnical, seismic, and hydrologic factors. The effort was a key element in protecting infrastructure, maintaining operations, and safeguarding public safety throughout the region.

Our firm delivered a holistic suite of dam safety engineering services tailored to each site’s unique challenges. We conducted extensive seismic, stability, and hydrologic analyses using industry-standard methods and finite element modeling. For both dams, we assessed critical structures, from powerhouses to fishways, developing seismic time histories and evaluating instrumentation systems. 

At Priest Rapids Dam, our team supported spillway remediation efforts by conducting structural stability evaluations, facilitating potential failure modes analysis (PFMA) workshops, and producing FERC-approved design documentation. For the Priest Rapids Spillway Stability Improvement Project, we designed and documented a complete rehabilitation plan using post-tensioned anchor systems and enhanced understanding through a 3D-printed model for visual engagement.

Beyond engineering, we led seismicity and concrete structure analysis training for regional utility staff and supported a Level 3 risk assessment to guide risk-informed dam safety decisions. Our collaborative, integrated approach aligned with regulatory requirements and delivered lasting benefits for the dam owner and community. The work also honored the historical and cultural significance of the Wanapum people, whose name the dam bears.