Economics of Inspection and Condition Assessment of High-Consequence Water Pipeline and Assessing Its Remaining Life

A probabilistic approach that considers the entire lifecycle cost of the water pipeline, accounting for deterioration rate, failure consequences, cost of rehabilitation, accuracy and cost of inspection/condition assessment, cost of emergency repair versus planned intervention and cost of total pipe replacement was introduced in an earlier paper. The approach allows us to combine expert-opinion (semi-informative assessment) with hard field data. New hard field data (e.g., failure events, inspection/condition assessment results) continually become available throughout the life of the pipeline. This incoming data stream can be incorporated into the analysis to provide robust, well-informed and reproducible assessment of deterioration rate and remaining life. The framework was implemented in an MS-Excel-based decision support tool, referred to as pipeline inspection decision analyzer (PIDA). This paper demonstrates the practical application of the proposed framework in the real world through comprehensive case studies, data for which were obtained from collaborating Canadian and US water utilities and pipeline owners. As is always the case in reality, most pipeline owners did not have all the required data to carry out a fully informed analysis. We illustrate how one might deal with missing data, how PIDA may be used to arrive at well-supported, rational decisions on when to deploy inspection and condition assessment, what techniques/technologies to select among competing ones and when it is time to stop assessing the pipeline condition and plan for replacement. Sensitivity analyses are also conducted to explore how various assumptions, necessitated by uncertainty, may impact analysis results.