Integrated Infrastructure ​Asset Management
Ben Ward
2011
Mülheim |11
LESAM, Mülheim |11
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A multi-objective optimisation model for sewer rehabilitation considering critical risk of failure
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​​A unique methodology for the optimal specification of sewer rehabilitation investment is presented in this paper. By accounting for the critical risk of asset failure, this methodology builds on previously successful work which explored the application of multi-objective optimisation tools to assist engineers with the specification of optimal rehabilitation strategies. The conventional sewerage rehabilitation specification process relies on the expertise of professional engineers to manually evaluate the CCTV inspection information when determining the nature and extent of the rehabilitation solution. This process is not only tedious and subjective but it has no quantifiable means of identifying optimal solutions, or, possible combinations of optimal solutions in the delivery of catchment wide rehabilitation programmes.
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Therefore, the purely manual process of sewer rehabilitation design leaves a number of unanswered questions, such as: (1) Does the solution offer the greatest structural benefit to the network? (2) Is the solution the most cost effective solutions available? And, (3) Does the solution most greatly reduce the risk of critical asset failure? The application of a multi-objective genetic algorithm optimisation model, coupled with an enhanced critical risk methodology, has successfully answered these questions when applied to a case study data set provided by South West Water (UK).​
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Exeter |11
CCWI, Exeter |11
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A multi-objective optimisation model for sewer rehabilitation considering critical risk of failure
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Without human intervention, sewerage infrastructure assets deteriorate and fail with time. The extent, value and age of the UK sewerage system demands the use of cost effective maintenance strategies to ensure that the UK sewerage systems are operated efficiently and economically. In 2010, Ofwat the industry regulator for England and Wales, estimated the total length of sewer assets to be 324,500 km. Of this asset stock, the reported total average renovation and replacement since 2000 has been only 334.9 km per year. Under this relatively low rate of replacement and renovation, it has become increasingly more important for water and sewerage companies to effectively prioritise the identification and remediation of defective high risk sewerage assets, in-order to deliver an adequate level of service to its customers.
AECOM have developed a suite of Hydroinformatic tools termed the asset investment tool suite (ai:Tool Suite). A selection of these tools have been implemented to help delivery South West Water’s target of stabilising and reducing sewer collapse rates: asset investment modelling (aiM), asset investment decision environment (aiDE) and the asset investment versatile export routine (aiVER).
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