ABSTRACT
As our urban environments expand, underground utilities need to accommodate the increased use and effects of climate change and severe weather events. In recent years, Auckland has been impacted by severe rain events, successive flooding, and a cyclone in 2023. The Orakei Main Sewer was constructed at the beginning of the 20th century and has a non-circular-shaped tunnel that consists of an unreinforced concrete invert and brick lining at the crown. In September 2023, part of the sewer collapsed, creating a large sinkhole at the surface and causing uncontrolled discharges of untreated sewage into the Waitematā Harbour. Preceding the incident, the amount of rain in the first nine months was 50% more than the average for an entire year. This paper discusses the climate change effects on ageing assets, lessons learnt from this incident, and how other similar assets could be maintained, and their design life expanded.
