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EVALUATION OF OPPORTUNITIES TO IMPROVE STRUCTURAL INSPECTION CAPABILITIES FOR WATER MAINS: LARGE DIAMETER CAST IRON PIPE
Citation:
Matthews, Ph.D., J., B. Nestleroth, Ph.D., W. Condit, P.E., AND J. Thomson, C.Eng. EVALUATION OF OPPORTUNITIES TO IMPROVE STRUCTURAL INSPECTION CAPABILITIES FOR WATER MAINS: LARGE DIAMETER CAST IRON PIPE. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-13/078, 2013.
Impact/Purpose:
Recognizing the importance of structural inspection, and its shortcomings, as well as the many potential options for its improvement, U.S. EPA’s Office of Research and Development identified evaluation and improvement of structural inspection technologies as an important component of its aging water infrastructure research program. Selection of the most promising structural inspection technologies to evaluate and/or improve is challenging due to the number of factors to be considered. This project provides a protocol for screening innovative structural inspection concepts and technologies. The protocol is focused on a single scenario -- large diameter, cast iron water mains -- because (a) it substantially reduces the complexity of the decision protocol, (b) high consequence failures of this type have already occurred and remain of concern for older cities; and (c) research by others has provided new insights into the causes of these failures that enabled important pre-failure indicators to be identified and quantified.
Description:
The U.S. EPA and other organizations have projected that a large portion of the United States’ aging water conveyance infrastructure will reach the end of its service life in the next several decades. EPA has identified asset management as a critical factor in efficiently addressing this projected surge in water conveyance infrastructure renewal. An important tool in the asset manager’s toolbox is cost-effective structural inspection, since it provides data to help support optimized capital, operations, and maintenance planning. However, there are many gaps in structural inspection capability and affordability, and many options for addressing those gaps. Recognizing the importance of structural inspection, and its shortcomings, as well as the many potential options for its improvement, U.S. EPA’s Office of Research and Development identified evaluation and improvement of structural inspection technologies as an important component of its aging water infrastructure research program. Selection of the most promising structural inspection technologies to evaluate and/or improve is challenging due to the number of factors to be considered. This project provides a protocol for screening innovative structural inspection concepts and technologies. The protocol is focused on a single scenario -- large diameter, cast iron water mains -- because (a) it substantially reduces the complexity of the decision protocol, (b) high consequence failures of this type have already occurred and remain of concern for older cities; and (c) research by others has provided new insights into the causes of these failures that enabled important pre-failure indicators to be identified and quantified. The initial target audience is EPA’s aging water infrastructure research planning process. The protocol is expected to be used as a guide for periodic reviews of the prospects of emerging structural inspection technologies for large diameter cast iron water mains. Also, this protocol can potentially be utilized by other organizations or individuals who are considering supporting or conducting water or wastewater pipe structural inspection technology research. The protocol can potentially be modified to address other high-interest pipe scenarios, such as large diameter ductile iron, pre-stressed concrete cylinder pipe (PCCP), asbestos cement, and steel. The protocol contains three levels and is used to evaluate eight technologies (four existing and four emerging) to determine whether the protocol is implementable and produces reasonable results. The report provides a brief overview of the potential failure modes, mechanism, and distress indicators for high risk cast iron water mains. This report also briefly discusses structural inspection technologies and the key stakeholders involved in structural inspection technology research and development. The protocol guides information collection for proposed technology developments including: the potential for inspection of water mains, the ability to detect specific anomalies or abnormal operating conditions, the cost of the technology development, and the potential cost of utilization by water companies. The application of these protocols was successful in demonstrating the potential of eight technologies, four of which showed the potential for further development for detecting critical distress indicators in a relatively cost-effective and reasonably implementable manner. The other four were considered to be inappropriate for further development for use on large diameter, cast iron water mains.