WET News

18 WET NEWS FEBRUARY 2016 THE CONCEPT • WaterGEMS is a comprehensive, easy-to-use decision-support tool for water distribution networks • The software helps improve knowledge of how infrastructure reacts to operational strategies • WaterGEMS' TRex feature was used terrain elevation extraction • The WaterGEMS Scenario Comparison feature helped find the right balance between energy use and number of reservoirs THE VERDICT "This process has allowed us to be confident that we have selected an option that will provide the best 'bang for our buck' while delivering adequate levels of service to the customer" Tracey Hamer, MidCoast Water A solution: Hydraulic modelling proves a scenario gem Bentley's WaterGEMS has helped Australia's MidCoast Water save thousands of dollars. M idCoast Water used the asset information con- tained in its database to develop a hydraulic model us- ing WaterGEMS' ModelBuilder function. The water network as- set information obtained upon handover of the Gloucester Wa- ter system to MidCoast Water was patchy, with some missing and incorrect data, including el- evations, pipe materials, and diameters. Missing elevations were addressed using Wa- terGEMS' TRex feature for ter- rain elevation extraction, to- gether with half metre contours NEED TO KNOW 1 The concept works cost may have been as high as AU$95,000 if the options analysis had been done manually 2 Gloucester residents were experiencing pressure fluctuations and the water supply system relied entirely on booster pumps 3 The existing water system contains nearly 30km of asbestos cement pipe installed between the 1930s and 1980s 4 Eleven main breaks and one leak were reported in Gloucester over a 24-hour period INSIGHT IT & TElEMETRY obtained by aerial laser survey. Tracey Hamer, planning engineer at MidCoast Water, explains: "This provided a sound basis for developing a working hydraulic model. WaterGEMS, and its powerful database, was used to create, analyse, and compare various scenarios, including future demand and fire-flow scenarios." To determine the best solution, MidCoast Water used WaterGEMS to develop more than 100 what-if scenarios – assessing various combinations of reservoir heights, pressure reducing valve locations, and water demands. With WaterGEMS, MidCoast Water could compare the energy use of various options, including doing nothing, even though this was not a viable option. WaterGEMS also analysed various options with large water reservoirs at varying elevations and varying numbers of pressure reducing valves (PRVs) placed within the system. The options with a higher reservoir required more PRVs (due to the number of pressure zones within the system) and so had higher ongoing energy costs and carbon emissions, due to the increased energy required to pump water up to the reservoir. The WaterGEMS Scenario Comparison feature helped MidCoast Water find the right balance between energy use and number of reservoirs. Using the information from the hydraulic model allowed MidCoast Water to select a sustainable solution based on modelled pressures experi- enced by the customer, pipe velocities, capital costs, and ongoing operational and maintenance costs, including energy costs. The options that were assessed required an initial outlay of AU$7M-10M (£3.5M- £5M), except for the existing system that would require a smaller outlay to fix existing reservoirs. The solution Mid- Coast Water chose involves constructing two new reservoirs to replace the three inadequate reservoirs, and constructing new mains to connect the new reservoirs to the water treat- ment plant and the existing distribution system. This option also includes decommissioning six out of seven booster pump stations, installing one PRV, and upgrading some pipes. Hamer says: "The scenario analysis undertaken in WaterGEMS allowed us to identify and test several options that meet the project objectives. A net present value (NPV) analysis was then undertaken to compare all feasible options. This analysis was performed outside of WaterGEMS but utilised information from the hydraulic models such as scenario energy use and pipe diameter and length for cost estimating. Scenario analysis and comparison using Water- GEMS allowed us to find an option with the lowest NPV (at 4%) over 50 years. "This process has allowed us to be confident that we have selected an option that will provide the best 'bang for our buck' while delivering adequate levels of service to the customer." Once the system improve- ments are complete, MidCoast Water will see reduced ongoing operational and maintenance (O&M) costs due to the decrease in energy requirements. Annual O&M costs are predicted to decrease by more than 75%. Over 50 years, system improvements will reduce the NPV of O&M costs by more than 80% (mainly due to reduced energy costs, but also due to reduced pump maintenance and main breaks). The volume of water storage in the system will also increase, which augments the secure yield of the supply system. Using WaterGEMS to analyse and compare 100-plus scenarios greatly reduced the time for the investigation, option selection, and concept design stage of the project from months to a matter of weeks. In addition, using WaterGEMS enabled MidCoast Water to reduce the cost of delivering the project by significantly reducing the time to complete the concept stage. The cost of the concept works was AU$15,700 (£7,700), and may have been as high as AU$95,000 (£47,000) if the options analysis had been done manually. WaterGEMS analysed various optionsat various elevations and varying numbers of PRVs The use of WaterGEMS enabled MidCoast Water to compare more than 100 scenarios, reducing the time of the concept design stage and investigation to just weeks rather than months

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