Valve Criticality Modeling

The aim of the "Valve Criticality" project undertaken by Thames Water, UK is to identify critical valves within the Company's water supply network, in terms of their potential impact on the customer levels of service, either when they are shut or fail to shut, during planned or emergency work. The consequence of each valve operation can be measured in terms of the number of properties being disconnected or receiving an unacceptable level of service (e.g., low pressure). An additional benefit of the project is increased knowledge on the system operation, which will enable maintenance and replacement work to be prioritised to the most critical valves. As it is not always obvious which valves are the most critical within a water supply network, the decision was taken to make the assessment using an all mains hydraulic model of each water pressure zone. However, with many thousands of valves to analyse, each requiring separate model runs, even a small zone could take over a week to analyse using conventional modelling software. A decision was therefore taken to approach MWH Soft to enhance their InfoWater Protector modelling software to automate the process so that thousands of valves could be analysed in one batch of model runs. A careful specification of the output results was required to avoid vast quantities of data being produced. Network trace techniques were used to identify each section of the network to be closed in, and the next available valve, should the targeted valve fail to close. The InfoWater Valve Criticality Modeling (VCM) module was released to users on the 13^th May, 2006, ahead of schedule. MWH Soft has now successfully provided Thames Water and all InfoWater users with the capability to assess the Criticality of the many thousands of valves within major supply networks, enabling maintenance and replacement to be targeted to critical valves. The module will help Utilities develop an optimal investment regarding infrastructure maintenance, minimising the impact on customer levels of service and improving knowledge on the operation of the network. The tool is being developed alongside a risk assessment module, also using Info Water, that assesses the impact of valve operation on water quality within the network. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).