Regional-Scale Seismic Vulnerability Assessment of Medium-Sized Water and Wastewater Systems

Seismic vulnerability studies are essential for resiliency planning and prioritization of seismic retrofit projects for spatially distributed critical infrastructure. However, detailed seismic evaluations of medium-sized water and/or wastewater systems are not always economically viable. We performed regional-scale vulnerability studies for two medium-sized water and wastewater systems in areas of moderate and high seismic hazard. The seismic hazards considered in these studies included strong ground shaking, fault rupture, liquefaction, and seismically induced landslides. The studies built upon publicly available information to assess seismic-related hazards and identify the most vulnerable areas with consideration for the full system. Developing a backbone system for each study allowed for prioritization of recommended mitigation projects. Areas of uncertainty and high vulnerability were identified to inform more detailed and targeted studies. The approach used in this study can be applied by engineers and owners to vulnerability studies for other distributed systems to inform resiliency planning and prioritization of mitigation projects.