Case Studies on Water Pipeline Failures in the Active Zone

It is estimated that there is nearly one million miles of drinking water pipelines in the U.S with an asset value of a few trillion dollars. The ASCE Infrastructure Report rates the water infrastructure to be D^–1 and hence there is need to investigate the conditions of the water pipelines. Based on our recent survey, most of the small diameter water pipelines in the major cities are placed within the top 1.5 m depth below ground surface. Hence the water pipelines that are buried in the active zone will experience notable changes in the soil moisture content over the year. In the active zone, soils would be affected by the environmental conditions. In this study, national survey results are presented and analyzed to determine the trends in the water pipeline failures. Based on literature review and experience, potential modes of failures for the small diameter water pipelines have been identified. In the survey conducted by the U.S. Conference of Mayors (USCM) has shown that 20 cities are reporting over 500 water pipeline breaks per year, and the CIGMAT survey showed that this could be much higher in some cities. A few case studies on water pipeline failures in the active zone in the City of Houston, Texas have been discussed.