All water pipelines are sized for fire flow requirements, to ensure that sufficient pressures and flows can be achieved at any point in the system. This allows the fire service to extract sufficient water at a sufficient pressure from the system, and therefore enable fires within the network area to be extinguished, while also ensuring that service levels are not compromised.
The WaterMax modelling program had originally been used to create hydraulic fireflow models. However Sydney Water had recently moved across to using InfoWorks WS as part of the recently implemented Water Modeling System, and therefore the decision was made to convert all of the WaterMax models to InfoWorks WS format.
The team of five engineers from GHD took a systematic approach to the project. GHD created a QA sheet to ensure quality control throughout the process, along with a management control sheet, which detailed the state of completion and readily provided progress updates. The management sheet was essential for the conversion of so many models - the spreadsheet indicated the number of models and elements of the work that had been completed, and by whom.
A standard conversion instruction document was also developed at the start of the program and updated throughout; ultimately becoming 24 pages long. Ensuring this was consistently used by all team members proved a significant project objective.
The methodology involved a quality assured progress with each model validated against WaterMax results. The approach taken was to extract flow, pressure and attribute data from the WaterMax model, then run the WaterMax to InfoWorks conversion with the appropriate projection. Additional manual conversion steps were then undertaken if required.
Engineering validation was undertaken using features included in InfoWorks WS to allow the model to run; and the flow, pressure and attribute data was then extracted from the InfoWorks model and compared with the original. Following this, any outstanding QA issues were resolved as necessary to ensure that a correctly converted model was ultimately produced.
The key strengths of the InfoWorks/WaterMax converter were that it provided precise spatial conversion of utilities, and ensured that general facility details such as pipe diameters, lengths, friction constants, fixed head details and ground levels were all without error.
The converter was flawless in resolving demand issues such as node demands, the demand diagram and demand scaling. The validation tool allowed GHD to detect issues within the networks such as isolated networks and overlaying links.
Different models had flows in litres/sec or MLD - requiring the missing local loss coefficients for valves to be calculated and entered manually. Furthermore, the use of a precise gravity value proved important in the calculation of local loss coefficients over extended simulations.
The end result of the careful conversion process was that the project was completed one month early, with every model QA checked.
A number of lessons were learned from this exercise, including the need to allow conversion of spatial data to MGA 56 or other formats at any stage of the process. The modellers also postulated that QA should be incorporated into the conversion itself.
In conclusion, the project proved that InfoWorks WS was very good at undertaking the conversion of WaterMax models, and most limitations were easy to overcome, particularly as consultant GHD had the experience and knowledge necessary to undertake major modeling programs.
This article is based on a presentation by Andrew Rode and Mike Healey of consultants GHD to the Wallingford Software InfoWorks WS user group conference in Sydney on 22 November 2007.