Survival Rate Analyses of Watermains: A Comparison of Case Studies for Canada and Iran
Frequent watermain failure is a major challenge for water utilities around the world. A quantitative picture of failure time, and the rate of failure for different types of watermains provide the opportunity for utilities to implement efficient proactive asset management strategies to minimize the overall cost of operations.
The Kaplan-Meier survival analysis is carried out for the time-to-failure in the watermains in two different case studies, one in Canada and one in Iran. At first, the time between failures for each material of watermains were estimated. Then, the rates of survival for the pre-dominant pipe materials, namely cast and ductile iron, are compared. In both data sets, cast iron pipes show fast deterioration rates relative to other types of pipe materials. The results demonstrate that cement mortar lined (CML) pipe and cathodic protection (CP) are generally promising for improving the life expectancy of metal watermains. From the engineering point of view, the results provide asset management information for rehabilitation scenarios based on a list of priority parameters.
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