Klohn Crippen Berger (KCB) performed a dam safety review of Mayo and Wareham Dams for Yukon Energy in 2005. That review identified a potential deficiency in that the seismic hazard had not been assessed in nearly two decades, despite advances in understanding of seismic hazard in Canada.
KCB subsequently performed a seismic hazard analysis to determine the seismic design parameters for the Maximum Credible Earthquake (MCE) for these “very high” consequence category dams. The Geological Survey of Canada (GSC)’s seismic hazard model which formed the basis for the seismic design provisions in the 2005 National Building Code of Canada (NBCC) was modified to reflect the local tectonic details and used in conjunction with the latest information on recent earthquakes and the current state-of-practice seismic hazard analysis methodologies.
Stability analyses were then performed for Mayo dam, a timber crib structure, and for Wareham dam, an earthfill dam with gated spillway structure. Global stability analyses used a pseudostatic approach to determine whether more detailed (deformation-based) analyses would be required. Liquefaction potential was investigated for both dams, and the non-liquefaction seismic performance was also assessed. Wooden and concrete structures were assessed using a capacity – demand approach. The stability under normal conditions and probable maximum flood was also assessed.
- Seismic hazard analysis
- Stability analyses