Van Heck, G.J.; E. den Haak and J. Kuit: Condition assessment and risk management of water mains saves tens of millions of Euros?. In: Proceedings of the International Public Works Conference, August 21 – 25 (2011). At: National Convention Centre, Canberra, ACT, Australia.
Waternet is the first Dutch water company that covers the complete water cycle and is responsible for the management of drinking water, wastewater, surface water, groundwater and safety behind dikes in Amsterdam and surroundings. Waternet takes care of a three prestressed concrete water mains laid in 1953 and 1964, with diameters of 1.5 and 1.2 meter, a total length of 210 kilometres, which provide pre-treated water to industry and a drinking water production plant of Waternet. Yearly about 100 million cubic meter of water is transported through these mains. After replacing and relining the most troublesome parts of the mains, a high number of leaks kept appearing. In 2003 a desk study was carried out and concluded that part of the leaks were caused by hydrogen embrittlement. The recommendations of the study included replacing another part (>10 kilometres) of the mains. Instead of replacing the main an extensive research was started in 2005 to get better insight in the causes of the leaks and the condition of the pipeline. The research included, among others, identification of wire breaks of the prestressed wire in the pipe elements (using Eddy Current technology), determination of causes of wire breaks, determination of the properties of the concrete and iron, modelling the strength of pipe elements, leak detection (using Smartball technology) and internal inspection of the pipeline including measuring the joint openings. A risk analysis was carried out to determine the risk of pipe burst and leaks related to the supply continuity and the surroundings. The outcomes of this research highlight the critical parts of the pipeline. In 2011 additional research, pilots for leakage monitoring and a scenario analysis will be carried out. For each scenario an investment, monitoring and maintenance plan for the coming 40 years will be worked out.