Pipe Performance and Experiences during Seismic Events in New Zealand over the Last 25 Years

Functioning pipeline systems are a cornerstone of urban human communities, to bring in the clean water on demand for drinking, washing and sanitary needs, and in turn remove the used water from drains, waste, and stormwater sources. If the pipe system is suddenly rendered partially or totally non-functional, such as by seismic event; critical disruption of the community and public health danger may result. Pipeline systems carry many requirements for design, including hydrostatic stresses, basic internal and external load bearing capacity, or axial loads from trenchless installation methods, such as horizontal directional drilling. Seismic events however, provide arguably the most arduous demands on a buried pipeline asset, owing to the extreme ground forces, and variable ground movements that are possible, and critical need to restore function to damaged pipe systems as quickly as possible. Pipe system design, materials, install methods, repair methodologies and practical implications of operation are all directly affected by seismic activity. This paper includes first-hand observations and experiences, specific to pipeline systems in New Zealand seismic events, covering a 25 year period, from 1987 to 2012. These events provide us with a unique opportunity to practically evaluate the seismic performance of pipe materials and joint systems, that either survived, or were damaged and repaired, or were totally destroyed and abandoned, specific to New Zealand seismic conditions. This paper concludes with some overarching lessons learned from these events, in regards to pipe systems.