Renewal of water pipes

Renewal of large diameter water pipes based on failure prediction
D Vitanage, C Crawley, D Zhang, J Rajalingam, S Rathnayaka, J Kodikara
Publication Date (Web): 6 September2018

Many major urban water utilities in Australia have significant numbers of cast iron critical water mains (CWM) that have been installed a long time ago and are in a state of reaching the end of their designed service life. The pipes have been subjected to gradual but continuous deterioration. Rapid urbanisation adds demanding operating conditions on critical water mains, causing high stresses. These factors lead pipes to fail. When they do they often cause significant impacts in terms of maintaining service levels to customers, loss of firefighting supply, safety issues, transport disruption and other social costs, as well as significant financial and reputational implications. This has been a serious challenge to water utilities, mainly due to the limited resources available to renew or replace these pipelines. 

To overcome these challenges, a consortium of local and international water industry organisations led by Sydney Water lead undertook a five-year (2011-2016) collaborative research project titled Advanced Condition Assessment and Pipe Failure Prediction (ACAPFP) project. The project was funded in cash ($5.9 million) and in-kind funding of $16.5M million. The research partners of the project were Monash University (lead), University of Technology Sydney and University of Newcastle. The overall goal of the project was to make definite advancement in critical pipe condition assessment and failure prediction. The project has advanced the fundamental engineering science in pipeline failure definition and corrosion development and also innovated several tools to predict critical water pipe failure. Throughout this project a number of aspects related to the performance of large-diameter cast iron pipes have been investigated, including relevant pipe failure mechanisms, existing failure prediction models, loading on pipes (both internal and external), new and existing pipe condition assessment techniques and pipe corrosion prediction models. New tools have been developed to predict pipe stress (taking into account more reliable loading, pipe properties, pipe condition, corrosion rates and associated uncertainties), to estimate the rate of pipe corrosion in respect to the pipes’ buried environment and new methods to improve the interpretation of the results of some commonly used pipe condition assessment technology. The significant outcomes from this research project need to be integrated into water utilities’ business practices with validation across a larger cohort of pipes to benefit customers and shareholders.

Sydney Water funded the operationalise phase of the ACAPFP project in 2017 to integrate research findings into the Sydney Water pipe network. The ‘Operationalise’ phase will cost up to $4M (including 200k for independent project management) over the next three years and will be funded by Sydney Water. To achieve a return on this investment, the water main renewal program needs to achieve at least a 4% efficiency in cost through operationalising the learnings from the ACAPFP project by the end of the 2016 - 2020 price period. This paper presents the key findings of the ACAPFP project, its early benefits, the reasoning to initiate the operationalise phase of the ACAPFP project and detailed information about the operationalise phase and the expected research outcomes of the operationalise phase.

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