The West Werribee Dual Supply Scheme (WWDSS) is planned by City West Water (CWW) to supply "fit for purpose" recycled water to residential estates and open spaces in the West Werribee region of Victoria, Australia. Recycled water will be sourced from Melbourne's Western Treatment Plant (WTP), desalinated then blended to achieve a product quality acceptable for use in residential settings. A dedicated recycled water pipe network running in parallel to the traditional potable network will supply the recycled water to residential toilets and garden fittings. Project supply will commence in 2013 by which time approximately 3000 lots will be connected. At full development in 2035 customers will comprise approximately 19,200 residential lots and 354 acres (143 ha) of open spaces. Ensuring an optimised supply system provides recycled water to dual pipe customers is important to avoid cost and energy inefficiencies. The recycled water demand profile is complex due to three significant factors daily demand variation, seasonal variation, and development growth. The system is being designed incorporating flow balancing, project staging and demand buffering to manage these complexities. As the recycled water from WTP is certified by the Victorian Environmental Protection Authority (EPA) as Class A, it is safe to supply to customers from a health perspective. However the salinity is too high for sustainable long term residential supply. To achieve the required product quality, with the least energy input, CWW will operate a desalination plant then blend the low salt permeate with an additional stream of WTP Class A recycled water, resulting in a shandy of optimal salinity. The desalination plant required to produce the permeate will be constructed in stages to meet demand. The first project stage will include construction of a plant to produce 8.1 acre feet per day (10 ML per day) of blended product recycled water. This recycled water will be fully allocated by 2019, at which time augmentation of the SRP is planned to cater for further growth to full development. This approach reduces the initial capital cost requirement to CWW, and optimal maintenance requirements through the first stage of operation. To meet peak summer daily demand CWW plan to construct a product storage system to buffer the daily peak across the summer months. This will avoid the extra capital cost and energy that would be required to construct a plant designed for instantaneous peak demand.
展开▼
