Development of a Risk Assessment Tool for Managing PCCP Assets with Broken Wires

Abstract

Aging pipeline infrastructure and limited funding for pipeline maintenance efforts make condition assessment an essential function in managing large-diameter pipeline assets for water agencies. Many of these pipelines are prestressed concrete cylinder pipe (PCCP) and, therefore, are subject to an elevated risk of failure attributable to prestressed wire breaks and continued corrosion of steel cylinders. Major water agencies must emphasize assessing and monitoring the PCCP pipelines’ condition. Condition assessments should include: (1) determining the pipeline’s structural condition by considering the number of wire breaks and the external and internal loads on the pipeline, (2) ranking the pipeline’s condition, and (3) prioritizing maintenance needs. Based on past research supported by the PCCP Users Group and the American Concrete Pressure Pipe Association (ACPPA), the use of risk curves in PCCP asset management has been successfully demonstrated in the existing literature. However, given the complex structural analysis procedures required for the design of PCCP and the development of appropriate representations for wire break conditions, analysis tools for creating such risk curves have not been widely developed for practical applications. This paper presents a Microsoft Excel spreadsheet-based risk assessment tool developed by the primary author to perform structural analyses and to create risk curves based on condition assessment findings, including wire breaks detected through electromagnetic data and corrosion damage to cylinders obtained from internal and external pipeline inspection. The spreadsheet tool uses the structural analysis approach outlined in the current American Water Works Association (AWWA) C304 standard and historical C301 and C304 standards. The paper also presents an example of the tool’s application to a risk-based condition assessment program. 1