AWWA ACE59963

This paper addresses decision-making issues faced by most water utilities regarding their water mains. An overview is provided to explain the difference between failure management of small-diameter mains in distribution systems and failure prevention in large-diameter transmission pipelines. The paper further describes past and on-going research at the National Research Council of Canada (NRC) on these issues. A description is provided for the application of fuzzy logic to assess failure risk of large diameter transmission pipelines. Case studies are described to illustrate the application of a multivariate time-exponential model to historical failure rates in small-diameter distribution mains. The impact of time-dependent factors on water main breaks is demonstrated, with special emphasis on the effect of various cathodic protection measures on the life-cycle costs of water mains. Includes 22 references, figures.