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WATER MANAGEMENT 44 E&MJ; • JANUARY 2017 www.e-mj.com by the existing supplies can be sufficient. By removing inefficiencies in control log- ic, a reduction in the overall number of bores operating and hence the overall run hours can be achieved. Applying Energy Costs to the Model The Darwin scheduler function within WaterGEMS optimizes the running of the system to achieve the lowest energy con- sumption while maintaining water supply requirements. It uses algorithms to run a high number of operating combinations, to determine the best combination based on preset criteria. This tool is generally used by Water Utilities to optimize running of pumps based on an energy tariff charged by an Energy Provider (i.e., a rate from a power company that changes throughout a day). In the Roy Hill case, the Darwin Scheduler is set up to optimize the num- ber of bore pumps running to maintain the water level in the main supply tanks while using the lowest amount of energy possible. The energy calculation is based on the fuel burn rate of the diesel gener- ators at each bore; the lowest energy con- sumption would lead to the lowest fuel burn rate on-site. The fuel burn rate for each bore is loaded into the model as the energy tariffs; with individual bore sites subject to different energy tariffs based on the Pump/Diesel Generator combina- tion at the bore. As an indication, within the Stage 1 Borefield, there are five dif- ferent pump sizes and four different gen- erator sizes. The Darwin Scheduler is set up to out- put the best three scenarios, which can then be checked against the EPS in the model to prove the minimum tank levels are maintained. It can be run weekly/ monthly/quarterly in line with changing water supply demands on-site or dewater- ing network expansion. Sharing the Data By outputting design and operational in- formation from WaterGEMS, it was easy to provide modeled data for discussion. This enabled the site water team to develop a greater understanding of the hydraulic system; from engineers on-site constructing to operators responsible for the running of the system. WaterGEMS imports aerial imagery, LIDAR, pit profiles, survey data and oth- er reference data from other internal Roy Hill departments to enable a clear work interface. Similarly, proposed design lay- outs generated by WaterGEMS were ex- ported in compatible formats for other de- partments to interpret and approve. While not the main driver, a byproduct of this is the environmental savings associated with an overall reduction in the use of raw materials for construction and fuel burn during operations. With the majority of the pipelines con- structed from HDPE, reducing the pipe diameter can save up to 37% by weight. To date, it is estimated that Roy Hill has used 635 metric tons (mt) of HDPE. Low- ering the operating pressure also reduces the pump and associated generator siz- ing/load. This leads to a reduction in fuel burn with a 25% drop in generator load reducing fuel burn up to 30%, and drop- ping a generator size reduces fuel burn by up to 20%. Accurate system simulations ensures that accidental or unapproved water dis- charge to the environment can be prevent- ed or controlled with more confidence. The operational optimization from the EPS and Darwin Scheduler targets a 20% reduction in fuel use. A 20% reduction equates to a savings of 3.6 ML (A$2.4 million) of diesel over the mine life (based on current projections); equivalent to 10 million mt of CO 2 emissions. By carefully modeling and designing the entire network, the operating pressure of the system has been reduced to less than 500 kPa. This means that 80% of all pipelines installed by October 2016 on-site are PN6.3 or PN8; 46 km of the 56-km network. It is estimated that this alone has contributed to a savings of A$1.6 million within the first two years of operations. Projecting this forward, it is likely to see savings in the order of $16 million across the mine's life. Reduction in equipment size costs is difficult to estimate. Given there were 48 bores installed by October, and reducing pump motor and genset size by one size can save as much as A$20,000 per site, it is estimated to have saved in the order of A$1 million. With anywhere up to 500 bores being installed, this could lead to a total savings of A$10 million. Having a fully modeled and well-un- derstood system has enabled the Water Management team to avoid costly rede- signs and alterations, which in itself can cost upward of A$1 million per project stage (materials and labor). By owning and controlling the hydrau- lic model, Roy Hill can complete all de- signs internally. It can take up to three weeks to arrange a consultant to com- plete works, which given the usual short turnaround timeframes required, is not feasible. Given the team is currently com- pleting five to 10 projects per year and a consultant can cost $10,000-$15,000 per project, there is a saving of as much as A$2 milion over the mine life plus multiple weeks of delays. This article was adapted from a case study submitted by Bentley Systems. They recognized Roy Hill with a Be Inspired Award in 2016. www.bentley.com By reducing the size of the pump and genset, the mine could save $20,000 per installation.