AWWA ACE69068

Failures on water mains have several negative consequences including disruption of service to customers, damage to the roadway, other nearby infrastructure and sometimes private property, alternative supply of water and detouring of traffic during repairs, financial cost of repairs, increased (albeit slight) risk of contamination in the water distribution system, and the conditions ripe for another failure when the main is re-pressurized. Customers' highly variable tolerance to service disruption, the high cost of water main replacement and the need for sustainability make for tough decisions by the utility manager. The dates and locations of failures however, provide a considerable amount of information about the condition of the pipe and the likely time between future failures. The authors present a statistical model for estimating the performance of each category of pipe to date. Segment level analysis uses the performance model to determine the economically optimum threshold for the replacement of each pipe in the network. Network level analysis then allows the analyst to forecast funding needs in relation to meeting the economic and service level objectives for the network. The effect of two co-variates, pipe length and pipe diameter, on the performance model is presented, as is the effect of different levels of service on the long-term funding needs. Includes 4 references, tables, figures.