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The Challenge
Roughly 70 per cent of the total asset base of a typical urban water utility consists of buried pipes in congested cities. In many cases large portions are old, some over 50 to 100 years, leading to increased water main failures incurring significant economic and societal costs. Consequently, the effective management to get maximum use of these vital assets while maintaining failures to a minimum has become a major challenge to water authorities.
Currently, water authorities treat large (typically over 300 mm in diameter) and small diameter pipe networks (typically less than 300 mm in diameter or known as reticulation network) separately in ranking their risk profiles by employing different approaches for pipe renewal and replacement.
These separate approaches are natural since large diameter pipes, also known as critical pipes, have fewer redundancies and their failures can lead to major consequences. Their failure modelling for remaining life predictions is also more involved since there is generally less failure data and failures are impacted by internal (pressure and transients) and external (corrosion, traffic loads etc) factors around the pipe barrels and joints. On the other hand, there is generally more failure data for small diameter pipes but the pipe failures depend significantly on reactivity of soils and prevailing climate.
In this regard, there is scope for developing an integrated framework where both small and large diameter pipes can be managed with due consideration of their relevant external/internal factors and failure risks.
The proposed framework will consider the complete network including both small and large diameter pipes and most relevant internal and external factors and social impact due to failure along the pipe networks in order to develop an integrated pipe failure prediction and asset management algorithms and modules for pipe renewal and rehabilitation. Altogether six modules are to be developed: pipe remaining life prediction module, reactive soil/climate interaction module, pipe water pressure/transient module, failure consequence module, probability of failure module and pipe risk ranking module.
The project will work in partnership with the current global project on Advanced Condition Assessment and Pipe Failure Prediction Project (ACAPFP).
The Project
With specific focus on partner utilities’ (SEW, MW, CWW,YVW) networks, this project will develop an integrated algorithms and modules using GIS framework to help undertake effective scoping and timing of replacement and rehabilitation of small (reticulation) and large diameter (critical) water pipes on the basis of the improved understanding of operating requirements and asset deterioration mechanisms. Altogether six modules are to be developed:
- pipe remaining life prediction module,
- reactive soil/climate interaction module,
- pipe water pressure/transient module,
- failure consequence module,
- probability of failure module, and
- pipe risk ranking module.
The modules will comprise GIS layers of pipe network, soil information (consistency, reactivity and corrosivity), topological information, road and traffic data, water pressure data (static and pressure transient), water table and urban settlement density. The pipe network will be populated with asset data, condition assessment and past failure records. Provisions will be made for input of additional data for maintaining the data integrity.
The framework will allow both top down and bottom up approaches for pipe ranking and selection for condition assessment, renewal and replacement. The top down approaches will include the use of statistical methods for analysing past data as especially applicable to small diameter pipes. These selections will consider climate and soil type in addition to other generic parameters, as developed at Monash through ARCSDP. The bottom up approaches will make use of the external and internal factors associated with each pipeline segment to make estimates of remaining pipe life and likelihood of failure, as mainly applicable to large diameter critical pipes. The framework will define the risk profiles of pipelines on the basis of probability of failure against consequence of failure. On the basis of the levels of uncertainty in decision making, appropriate condition assessments to improve the decision making will be provided.
The Outcome
The project was started in March 2014 and is to be completed in March 2017. The project milestones are planned roughly in every six month intervals with project presentations to project partners, Victorian water utility authorities and ACAPFP partners.
Beneficiaries of The Project
The beneficiaries of the project include project partners (Melbourne Water, South East Water, Yarra Valley Water, City West Water), the partners of the Advanced Condition and Pipe Failure Prediction Project and the Victorian regional water authorities. The material published in public domain will benefit the global water community who faces similar pipe network management issues.