Numbers Still Don't Lie - PCCP Performance Based on a Statistical Review of Fifteen Years of Inspection and Monitoring Data

Over the last thirty years, PCCP water and wastewater mains have been subject to a wide range of condition assessment techniques. In the past fifteen years, electromagnetic internal inspections and acoustic monitoring have become standard practice for critical large diameter PCCP water and wastewater mains. Electromagnetic inspections provide a baseline count of broken prestressing wire wraps for each pipe section, while acoustic monitoring identifies and locates wire breaks on an on-going basis. Together they allow clients to manage their PCCP in near-real time, enabling PCCP owners to understand the condition of their pipeline on a day-to-day basis and intervene when appropriate based on the specific number of wire breaks on a single pipe section and its corresponding structural state. In 2012, a study on the electromagnetic inspections and acoustic monitoring databases, provided by Pure Technologies, investigated the incidence of distressed PCCP and the rate of wire breaks recorded on individual pipe sections. Over the past three years, a more extensive database has been developed within Pure Technologies allowing for more comprehensive study, including investigation of the specific characteristics of deteriorated, active, and repaired pipes. This paper will review the data from approximately 3,000 miles of electromagnetic inspection and over 700 miles of PCCP currently being acoustically monitored with fiber optic cable. The paper will analyze a database of 44,000 individual wire breaks in over 185,000 prestressed concrete cylinder pipes. Although the database includes systems from all over the world, this paper will focus on data from inspections and acoustic monitoring systems located in the U.S. and Canada. The goal of the paper is to review and update the results of electromagnetic inspections and the acoustic monitoring database to analyze the performance of PCCP water transmission mains and sewer force mains. The study will evaluate the occurrence and rate of wire breaks within PCCP of various specifications and within different pipelines and loadings. The findings will be presented on a statistical basis, with associated confidence or likelihood for each conclusion. The data will also be evaluated for the suitability of working within a predictive model. The predictive model will estimate the possibility of pipe failures over future time horizons. The predictive model supports decisions related to the development of cost effective, long-term management strategies and planning capital replacement needs. The findings will help clients better manage their pipelines and further the industry's knowledge.