Impacts of liquefaction on the potable water system of Christchurch in the 2010–2011 Canterbury (NZ) earthquakes

This paper explores the performance of the potable water system of Christchurch during the series of strong earthquakes that hit Canterbury, New Zealand, in 2010–2011. Widespread soil liquefaction, consequent ground deformation (failures) and large lateral spreads shattered the lifelines and infrastructure over approximately one-third of the city area. The wastewater system was hit particularly hard, whereas the potable water system showed much greater resilience. Even though a large number of breaks/repairs were reported, the potable water service was quickly restored. Preliminary analyses of the repair records show a clear increase in the level of damage to the pipe network with increase in the severity of liquefaction (with nearly 80% of the damaged watermains being in liquefied areas), and that polyvinyl chloride and polyethylene pipes suffered several times less damage than other material pipes (i.e., asbestos cement, galvanized iron and steel pipes). Lessons learned regarding the performance of the system including development of performance objectives and liquefaction zoning maps based on earthquake observations are summarized.