Integrating 3D Hydrodynamic Modelling into DSS in a Large Drinking Water Utility
Dr Kathy Cinque and Dr Peter Yeates Presentation Overview
• Melbourne Water • System • Water quality and risk management • Modelling capabilities • Decision Support System (DSS) • Components • Case Studies • Recent modelling project • Future direction Melbourne Water
Supply drinking and recycled water and manage Melbourne's water supply catchments, sewage treatment and rivers, estuaries and wetlands
Drinking water • 4.1 million customers • 10 storage reservoirs • Biggest reservoir = 1,068 GL (280,000 million gallons) • Smallest reservoir = 3 GL (790 million gallons) • Protected water supply catchments • Total area = 1,600 km2 (400,000 acres) • 80% of water supplied is unfiltered but disinfected Location of Melbourne, Australia
Melbourne Melbourne Water supply system Risk management
Unfiltered supply means our reservoirs are an important barrier to contamination
Detailed understanding of hydrodynamics and water quality is paramount to ensuring safe drinking water • Fate and transport of pollutants • Risk of algal blooms • Event management • Impact of changes in operation • Strategic planning Decision Support System (DSS) framework
• Provides a single point of access 3D Hydrodynamic Model
Hydrodynamics - ELCOM • Uses an orthogonal grid • Simulates temporal behaviour of water bodies with environmental forcing • Models velocities, temperatures, salinities and densities Biogeochemistry - CAEDYM • Represents the major biogeochemical processes influencing water quality, including sediment Hydrodynamic modelling at Melbourne Water
• Drinking water reservoirs for over 10 years • Significant investment • 10 LDS’s in 7 reservoirs • Development of integrated modelling platform (ARMS) • Dedicated in-house modeller • Real-time and scenario analysis • Wastewater treatment plant mixing zone studies • Estuary research – seagrass, mangroves, toxicants Case Studies
1. Cardinia Reservoir • Desalinated water inlet shute location • Inform capital investment
2. Sugarloaf reservoir • Aerator operation/augmentation • Optimise operational decisions
3. Upper Yarra Reservoir • High turbidity inflow event • Incident management and response 1. Cardinia Reservoir – Inform capital investment
• Reservoir capacity 287 GL • Surface area 3,200 acres • Water stored is from protected catchments, unfiltered • Desalinated water to be added to natural water
• Model objective
• Best location for inlet to ensure mixing and dilution • Ensure consistency of water quality at outlet Model set-up
• 100 x 100 x 1m grid used • 4 locations modelled for each season, aerator on/off Proposed inlet location 1. Cardinia Reservoir – Inform capital investment
• Desal water is warmer than reservoir water so restricted to top layers • Mixing highly influenced by wind • Recommended location ensure mixing and consistent outlet water quality
Outcomes • Recommended inlet shute location adopted by the Capital team • Tens of millions of dollars saved by optimising site location 2. Sugarloaf Reservoir – Optimise operational decisions
• Reservoir capacity 96 GL • Maximum depth 89 m • Reservoir stratifies causing reduction in DO in bottom waters causing leaching of Fe and Mn into water column, subsequent biofilm build up in distribution mains • Existing aerator to deepen thermocline
• Model objective
• How efficient is the current aerator? • Is there a need to retrofit/replace/duplicate/relocate? • How does the aerator’s operation affect its effectiveness? Sugarloaf Reservoir model set-up
• 60 x 60m grid • 60 second time-step • 8 month simulation period • Inputs = inflow rate and temp and meteorological conditions • Calibration – LDS and grab samples
2. Sugarloaf Reservoir – Optimise operational decisions
Outcomes • Aerator location means it will not mix entire water column • Grab samples and LDS are in a “hole” giving false indication of mixing in the remainder of reservoir • Current aerator operation confines Mg to bottom waters and deepens thermocline • Turning aerator on after December means waiting a month for the thermocline to be lowered 3. Upper Yarra Reservoir – Incident management and response
• Drowned riverbed reservoir • 84,000 acre protected catchment • Risk of human infectious pathogens is very low but storm events can impact aesthetic water quality • June 2012 large storm
• Model objective
• Predict travel times and dilution of dirty water • Assist in operational decisions Turbidity event in Upper Yarra
9 km
(5.5 miles) Measured vs modelled Predictive turbidity modelling 3. Upper Yarra Reservoir – Incident management and response
Outcomes • Turbidity remained below 15 NTU at the dam wall - as predicted • Reservoir remained in operation based on predicted inflow intrusion being below offtake height • Model run in real-time to track turbidity and assist with sampling • Prevented issuing a boil water notice – saving millions of dollars Outcomes
• Broad range of operational circumstances and planning initiatives • DSS with integrated data and model provides a platform to efficient quantitative risk assessment • Accessible use and easy dissemination of information • Significant investment over 10 years to develop this capacity • Used to minimize the impact of what could have been serious incidents shows return for investment • Communication of initiative with Vic. Dept. Health has resulted in confidence in the approach and acceptance of the tools The future of modelling at Melbourne Water….
.. is now!!
• Hydrodynamic and water quality modelling in bays and estuaries • Predictive algal modelling in drinking water • Pathogen fate and transport • Wastewater treatment plant mixing zone studies • Estuary research – seagrass, mangroves, toxicants • Coupling catchment runoff models to receiving water models Thank-you for listening!
Dr Kathy Cinque ([email protected]) Dr Peter Yeates ([email protected])