Water Journal : Current August 2017
www.awa.asn.au 65 INTEGRATED WATER CYCLE SAVES WATER AT GOOGONG. Building a water resilient town C H Wong, K Hurley, C Harris I n the 2000’s Australia experienced the Millennium Drought, which affected water supply to almost all major cities. In the midst of the drought, a new township was being planned near the inland city of Queanbeyan, some 25 minutes’ drive southwest of Canberra. Being an inland city, seawater desalination is not a water supply option for the new township of Googong. To drought-proof the new town, embedded in the township’s master plan is an integrated water cycle (IWC) that comprises a variety of water conservation measures. AVAILABLE OPTIONS At the infrastructure level, the IWC includes: a water recycling plant; dual reticulation system for recycled water and potable water (including dual water reservoirs); a bulk water supply connection; three sewage-pumping stations; and water sensitive urban design for stormwater management. At the residential level, all dwellings need to comply with a design guide that mandates a minimum residential BASIX water score of 50. This promotes the uses of water efficient fixtures, rainwater harvesting and uses of recycled water. The IWC means that recycled water and rainwater will be used in place of precious drinking water for things like open space irrigation, flushing toilets, watering gardens, washing machines and fire fighting. All together these reduce potable water consumption in the community by up to 60%. This paper reports on the key challenges and lessons learnt for the planning and implementation of the IWC. OVERCOMING OBSTACLES At the planning level, one of the major challenges is to balance the competing effluent quality requirements for phosphorous and total dissolved solids (TDS). In a semi-closed water cycle, TDS will accumulate in the water cycle unless it is adequately managed. Dynamic models for water and TDS balances were employed to elucidate impacts of treatment technology and choices of end uses on the competing effluent quality objectives. Key outcomes include selection of phosphorous removal technology that uses the least amount of chemicals, adjusting recycled water end uses and appropriate lot sizing to maximise irrigation of recycled water. At the concept design level, the membrane bioreactor (MBR) process was selected to minimise the footprint of the WRP. The entire plant was covered and acoustically treated to minimise the odour and noise footprints. At the community engagement level, a recycled water education strategy was jointly implemented by the developer and the local council. This included community workshops, production of key fact sheets and letterbox drops to educate the residents on appropriate uses of recycled water. To date, stage one of the IWC infrastructures have been delivered. These include a state-of-the-art water recycling plant, two sewage pumping stations, interim water reservoirs and dual water reticulation networks that supply more than 500 homes. To validate the design assumptions, flow monitoring is currently in place to elucidate actual consumption of potable and recycled waters, as well as wastewater generation from the township. In summary, Googong’s IWC is an example of a progressive approach to create a water resilient inland community. When fully developed, the township of 18,000 people will use the same amount of water that 6500 normally would. Chiew H Wong is a principal engineer at Stantec Australia. Katherine Hurley is a civil engineer at Stantec UK. Craig Harris is assistant project director at Googong Township Pty Ltd. To read the full article, visit the Water e-Journal at bit.ly/water_ejournal executive summary water resources planning Googong’s integrated water cycle is an example of a progressive approach to create a water resilient inland community.
Current May 2017