Hong Kong's fresh water and flush water (salt water) supplies are provided through a sophisticated network of water mains, where most of them were underground. After a successful replacement and rehabilitation programme that significantly reduced the number of water main bursts incidents since 2000, the Water Services Department (WSD) aims to develop a risk-based system which combines the advanced analytical approach with physical condition assessment for continuous monitoring and improvement of these water mains.
Appointed by WSD, WSP’s Sustainable Development and Environment (SDE) team in the Hong Kong office, working with our experts from WSP UK, Australia and New Zealand, develops a comprehensive plan for such purpose, including strategies, decision frameworks, models and processes, over 12 months.
Our system will cover over 9,000km of water mains in Hong Kong, including 91 km of extremely critical ones for which the consequences of failure are unacceptable, posing a potentially high risk from the perspective of loss of water supply as well as financial, social and environmental impacts.
First thing first: quality data
WSD originally owned two separate internal databases: WSD Digital Mapping System (DMS) recorded the latest asset data of the existing water mains and WSD Maintenance Works Management System (MWMS) covered the historical failure data of the existing water mains. To develop a reliable model for the system, WSP first carries out a data cleansing exercise to consolidate the data from the two WSD databases. We are also tasked to develop a new data collection format for storage and conduct configuration of water main networks in GIS for full-scale visualisation.
Forecasting the failure score
Through analysing previous occurrences of repairs, breaks and leaks in addition to their incident location, WSP develop a performance score system to determine the probability of pipeline failure. The existing risk scoring tool will be modified, as required, to prioritise failure assessments.
Our failure forecast score system integrates a number of physical, environmental and operational factors for optimised prediction accuracy.
- Physical parameters: pipe material, age, slope, diameter, wall thickness, etc.
- Environmental parameters: pipe bedding, trench backfill, soil type, groundwater level, electrical currents, etc.
- Operational factors: water pressure, leakage record, water quality, velocity, etc.
Integrated long-term planning model
Our comprehensive risk-based planning model involves the use of Pipeline Asset & Risk Management System (PARMS) software to manage life cycle costs in line with ISO 55000, which includes failure forecasting tools, long-term planning models and GIS-based ranking tools. As our proposed solution is more efficient and future-proof over traditional Linear Extended Yule Process and KANEW methods, it will be the foundation for WSD to determine future long-term sustainable needs for water main improvement and develop what-if scenarios for maintenance planning, funding needs and predicted failure rates.