Water Journal : Water Journal August 2011
60 AUGUST 2011 water technical features governance Abstract Across Sydney Water's area of operations there are currently more than 20 recycled water schemes producing around 50 billion litres of recycled water per year. These schemes cover a range of end uses such as residential, industrial, irrigation, agricultural and environmental releases. In addition, the end users have varying capability for managing risks. While initial schemes were developed as simple effluent recycling operations, Sydney Water has seen a shift in understanding from effluent disposal towards resource recovery and manufacture of products. This emphasises the importance of risk management in recycled water schemes. Sydney Water has developed a framework for managing risks across this wide variety of schemes and end uses. This framework utilises Sydney Water's existing ISO-certified processes, which also incorporate the Australian Standard for risk management, AS4360:2004, and its replacement, AS/NZS.ISO31000:2009. This approach also accounts for the flow of risk from scheme inception through to ongoing operation, as well as the physical flow of risk from source to end use. A key principle of Sydney Water's approach is the identification, assessment and management of risk in the short term and over longer time frames. To establish background and context, this paper first reviews Sydney Water's recycled water schemes and discusses trends in the understanding of recycled water as a resource. The paper then discusses Sydney Water's framework for managing risk in recycled water quality and concludes with some comments on future directions in risk management. Overview of Water Recycling in Sydney Water Sydney Water has been involved in water recycling since 1967, starting with recycling at its own wastewater treatment plants and with a small number of local irrigation schemes. Its first residential dual reticulation scheme at Rouse Hill commenced operation in August 2001. Since then, other major recycling schemes such as that supplying BlueScope Steel at Wollongong, NSW, and Western Replacement Flows have begun. The Western Replacement Flows project produced its first commissioning flows in March 2010 and commenced full operation in August 2010. This scheme provides up to 18GL per year of recycled water for environmental flows to the Hawkesbury-Nepean river system. Sydney Water supplies recycled water for the following typical non-potable uses: • Residential (dual reticulation); • Industrial; • Municipal irrigation (primarily sports ovals, golf courses, etc.); • Agricultural (fodder production); and • Environmental releases. Recycled water for these schemes comes from Sydney Water's wastewater system and is treated to the required level for its end use. The 13 water-recycling plants that supply Sydney Water's schemes employ a range of treatment processes depending on the product quality required for end uses. There are also many stormwater recycling projects across Sydney; however, this paper does not cover these. Table 1 summarises Sydney Water's types of schemes, their typical uses, as well as volumes from July 2008 up to March 2011. The significant increases in production are primarily due to increasing connections in Rouse Hill, the BlueScope scheme, significant additional irrigation allocations and, most of all, the commissioning of the Western Replacement Flows scheme. Some of the variations in dual reticulation and irrigation consumption also reflect weather patterns. Figure 1 illustrates the current major recycling schemes in Sydney. These include all of Sydney Water's schemes, as well as the Sydney Olympic Park dual reticulation scheme run by the Sydney Olympic Park Authority (SOPA). Data from SOPA are not included in Table 1. All of Sydney Water's wastewater treatment plants (WWTPs) practise some form of on-site recycling and those G Landers, P Chapman Developing a consistent framework across a wide variety of uses RECYCLED WATER: MANAGING THE RISKS IN SYDNEY WATER Table 1. Summary of currently operating recycled water schemes. Schemes Uses Volume (GL) 2008/09 2009/10 2010/11 Dual reticulation schemes (Rouse Hill Recycled Water Scheme) Residential, commercial and irrigation (ovals, recreational areas, etc) 1.779 2.208 1.812 BlueScope Steel Recycled Water Scheme Industrial 6.652 4.390 4.962 Sydney Water's WWTPs' on-site recycling Industrial 14.916 15.631 12.255 Other schemes taken from Sydney Water WWTPs Irrigation (golf courses, sports fields and agricultural -- fodder) 1.192 1.717 4.629 Western Replacement Flows Environmental flow replacement NA NA 12.863 TOTAL 20.958 24.162 36.521 Note: The 2010/11 figures are year-to-date up to March 2011 (three-quarters of the year). Over the course of one year this equates to approximately 50GL/year.
Water Journal September 2011
Water Journal July 2011