An Integrated Dynamic Approach to PCCP Integrity Management

摘要

The recent development and application of technologies to inspect and monitor prestressed concrete cylinder pipe (PCCP) has provided new opportunities to manage deterioration in these large-diameter water and wastewater pipelines. Previously, little information was available about the extent and rate of deterioration of the prestressing wires in this type of pipe. Engineers had to rely on visual inspection and corrosion surveys to try to identify pipes approaching a critical structural condition, which could then only be confirmed through excavation and forensic examination. Now, however, electromagnetic inspection can provide a good approximation of the number of wires that have failed in a given pipe, and continuous acoustic monitoring can identify and locate wire breaks as they occur during the monitoring period. This information has been used to identify and replace severely distressed pipe and to assist in the development of repair or replacement programs. However, with few exceptions, this high-quality data is currently used only as part of a static approach, that is, information is collected from periodic electromagnetic inspection surveys or short term monitoring programs and decisions are made on the basis of an analytical or subjective assessment of risk of failure at that particular point in time. This can lead to the adoption of inadequate or over-conservative mitigation strategies. The combination of electromagnetic inspection, long-term acoustic monitoring and comprehensive dynamic risk management modeling provides an assessment of remaining time to failure for each pipe while protecting against spontaneous rupture. The integration of this information into a comprehensive database with an intuitive interface allows agencies to optimize PCCP management and offers a far more sophisticated and cost-effective solution to assuring pipeline integrity than current practice. This paper describes how such a strategy can be implemented and presents a case study on how one North American water agency is adopting this approach to manage its PCCP inventory.