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Failure assessment model to prioritize pipe replacement in water utility asset management

Date

2006

Authors

Rogers, Peter D., author
Grigg, Neil S., advisor
Roesner, Larry A., committee member
Vlachos, Evan C., committee member
Oad, Ramchand, committee member

Journal Title

Journal ISSN

Volume Title

Abstract

The condition of a water distribution system has strong correlations with community health and economic development. However, studies indicate an urgent need to upgrade the nation's aging and deteriorating distribution systems if they are to continue to provide customers with reliable and safe water supplies. In response, water utilities are using various performance measurement initiatives including pipeline asset management. These require assessment of each pipeline's condition to identify failure-prone pipes and prioritize their renewal. However, the below ground location of the pipes and lack of standard guidelines or tools to assist in assessment make pipeline assessment and renewal decisions difficult. In this research, a pipe failure assessment model was developed and tested to assist water utilities with their pipe renewal decisions. A conceptual model was created from a review of case studies, theories and asset management tools. The model consists of several modules (components) written in Visual Basic for Application (VBA) within a Microsoft Excel platform. Rather than requiring extensive field data to determine the cause of breaks, the model's failure prediction module and Multicriteria Decision Analysis (MCDA) modules use pipe inventory and break data compiled from the utility's existing operation and maintenance records. Recognizing that pipe renewal decisions are based on risk avoidance as well as on failure probabilities, a unique feature of the model is a consequence module that allows the decision maker to compare "what-if" infrastructure investment scenarios. The conceptual model was refined through collaboration of a focus group of water utility professionals. By drawing on the knowledge and experience of these experts, the review process added unique features that facilitate the model's use and responsiveness to the industry's needs. The model was tested using pipe inventory and break history information contributed by Laramie (Wyoming) Water and Colorado Springs Utilities. Although each water supplier differs in population served, operating conditions, pipe inventories, and pipe break histories, both utilities were able to provide their pipe inventory and break history in electronic form which facilitated the model processing. Evaluations from the participating utilities indicated that the pipe failure assessment model would enhance the industry's ability to prioritize pipe renewal decisions and improve their return on investment. Utility personnel indicated that the model's use of routine pipeline operation and maintenance records, combined with its consequence modeling features, addresses both the data limitations and risk avoidance characteristics of the industry in a way that is intuitive and understandable to utility staff. Utility personnel also commented that the model adds knowledge and transparency to the decision process, which is critical in an environment in which decisions will have to withstand scrutiny from various interest groups. Lastly, the investigation illustrates the need for better inventory and break data since this data plays such an important role in the industry's buried infrastructure planning programs.

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Subject

Water-pipes -- Maintenance and repair

Citation

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