Water Journal : Water Journal December 2012
refereed paper small water & wastewater systems water DECEMBER 2012 63 The City of Sydney The City of Sydney Local Government Area (LGA) covers an area of 2,660ha and is home to over 180,000 people. This number is expected to grow to 243,000 by 2030. The City’s economic activity represents 8% of the national Australian economy with over 20,000 businesses providing jobs for over 340,000 people today, with this expected to grow to approximately 440,000 by 2031, with Barangaroo redevelopment area expected to account for 23,000 of those alone. The city is an international tourist destination with over four million visitors per year. Figure 1 shows the three receiving water catchments – Sydney Harbour, Cooks River and Centennial Park – and the 11 sub-catchments. The City is bound to the north by Sydney Harbour and to the south by Botany Bay (both Cooks River and Centennial Park catchments ultimately drain to Botany Bay). Developing the Baseline The baseline mapping stage of the DWMP estimated current and future potable and non-potable water demands, potential decentralised supply sources within the city and how these may be linked. Baseline information was concurrently developed for the WSUD plan, identifying stormwater pollution loads for each sub-catchment within the city. Spatial analysis tools were critical in synthesising and communicating the scale and location of the opportunity, water quality and temporal information. Demand Existing metered water demand data (on a building level) was correlated with a three-dimensional highly detailed floor space model for the City. By simplifying floor space by sectors and statistical analysis, reliable estimates of water use by sector were developed. Further analysis of end-use data for each sector provided an estimate of the volumes that could potentially be supplied by alternative water sources. The analysis indicates that the City of Sydney accounts for approximately 7% of Greater Sydney’s water demand with approximately 80% of that consumed within the CBD. The analysis of sector end uses indicates that 50% of the current potable water demand could be substituted with alternative waters. Notably, irrigation accounts for less than 3% of the current demand, with the majority of non-potable water uses associated with toilet and cooling tower demands. Future demand analysis was undertaken using Local Environmental Planning (LEP) guidelines and capacity analysis to estimate growth in each sector out to 2030. Sector growth represented additional opportunities to incorporate innovative alternative water use designs into building and landscape renewals and refurbishments. Based on this growth analysis, it was estimated that greater than 54% of potable water demand could be substituted with alternative water supplies if available, with growth accounting for 18% of forecasted alternative water demand in 2030. Specific sector buildings and floor space water use intensities were compared with industry best practice benchmarks to understand the opportunity for increased end-use efficiency. The granularity of the data provides an opportunity to engage directly with building occupants and owners to reduce water use through efficiency measures. This analysis formed the basis of a separate water efficiency plan completed by project partners, the Institute of Sustainable Futures. Alternative Water Supply and Demand Opportunities Having identified current and future non-potable water demands across the LGA an analysis of potential supply options was undertaken. In summary this included: • Stormwater generated within the city and transferred via the stormwater system to receiving waters; • Wastewater that was generated within, and transferred through, the city; Figure 2. Location of water use within the City of Sydney. Figure 3. Water end use analysis by sector.
Water Journal February 2013
Water Journal November 2012-1