Towards optimum condition assessment policies for water and sewer networks

With ageing water and sewer infrastructure in North America, assessing the condition of these assets has received increased attention in the past few years. Condition assessment is an integral component in any asset management program. Determining the condition of buried infrastructure tends to be more cumbersome, costly and error-prone compared to other surface infrastructure like roads and buildings. For sewers, CCTV is considered the industry standard for condition assessment technologies. For pressurized water pipelines, technologies tend to be more costly and uncertain (e.g. electromagnetic, sonar, acoustic leak detection, infrared etc...). Faced with constrained budgets and the need to obtain reliable condition information to drive their asset management processes, infrastructure owners must balance the value of information obtained through condition assessments with the cost of obtaining this information. This paper presents an analytical framework and decision support system to evaluate the value of information for condition assessments of water and sewer infrastructure. The framework considers: 1) risks associated with operating the asset, 2) potential direct and indirect costs of infrastructure failure, and 3) customer expectations for the system's level of service. The decision support system utilizes Partially Observable Markov Decision Process (POMDP) to compare between the reliability and cost of the condition assessment technology. The system is demonstrated on the water and sewer networks for the City of Hamilton, Canada. Copyright ASCE 2010.