The Cambridge water supply is from two large reservoirs on the Hill by the Karapiro reservoir. These reservoirs are critical network assets that ensure continuity of water supply to the township. The prominent location of these reservoirs would result in significant property damage and cultural issues should they fail in service.
Waipa District Council during the last Long Term Plan (LTP) cycle invested significant funds into understanding the criticality of its various water assets and using these to determine the priority for their condition assessment. This philosophy for this approach was to drive effective planning and results in an optimized asset replacement strategy for the LTP.
As critical assets the reservoirs at Karapiro reservoirs had an external, visual condition inspection in October 2012. This inspection noted water ponding on the roofs of both reservoirs and suggested an internal inspection be undertaken. To minimize operational outage of the reservoirs during a period of high water demand an internal inspection was only undertaken in October 2013 using divers. The photographic evidence from the divers indicated significant issues with the internal roof support structures of reservoir 1 in particular with a need to take urgent action.
Waipa instigated immediate measures to restrict access to the reservoir roofs and implemented emergency physical works to repair the roof supports to ensure continued service of the reservoirs post the summer demand period. These repairs were undertaken in September to October of 2014 in a collaborative and innovative way between Council, Opus Consultants and Brian Perry Civil due to the uncertain nature of the extent of repair required and again with the program pressure of having the reservoir back in service before the summer period.
The paper will discuss the cradle to grave asset management philosophy as applied by Waipa with regard to the Karapiro reservoirs and how an understanding of asset criticality and condition can lead to enhanced plant understanding, performance and risk mitigation.