Water Journal : Water Journal December 2012
refereed paper sustainability water DECEMBER 2012 87 Recognising this as the ‘elephant in the room’, Yarra Valley Water worked with AECOM to investigate if it was possible to deliver a more sustainable outcome in existing development. The Blackburn region, located approximately 13km from the Melbourne CBD, was selected as an ideal site, if there were any. It had an existing lake that could be used as a storage reservoir, a large percentage of existing infrastructure near the end of its life, access to both stormwater drains and large sewers for alternative water sources, and the existing system required a large amount of energy to operate (1,700 kWhr/ML). Eleven alternative infrastructure options were studied. These included centralised improvement options using demand management strategies and/or the use of a buffer tank to manage peak demands, decentralised in-house options for the harvesting of roof runoff and/or reuse of greywater, and precinct and/or catchment infrastructure options that involve sewer mining and/or stormwater harvesting options treated to non-potable or potable standards. All analyses compared each alternative option against the existing base case service in place at the moment. The eleven infrastructure options were all designed in sufficient detail so that they could be modelled to size the required infrastructure. An economic NPV was undertaken. It included all of the costs borne by all of the infrastructure elements, independent of who incurred the costs, which was termed the community cost. And finally, an analytical hierarchal process (AHP) multi-criteria analysis was used to bring together all of the contributing variables so that the most promising solutions could be identified. Three were found to deliver more sustainable results and be economically viable (Lloyd et al., 2012). Stormwater treated to potable standards to supply all demands required a service area of 2,200 residential properties. Sewer mining to supply non-potable demands requires a larger service area of 4,100 properties to return a positive NPV or a nitrogen price increase of 17%, which equates to an increase from $2,200/kg to $2,560/ kg. And finally, stormwater to supply potable demands combined with sewer mining to supply non-potable demands became viable when the area serviced was 6,000 properties – or alternatively, as was the case in this study area, where the number of properties serviced was limited to 4,100 (set by the extraction threshold from the sewer to maintain cleaning velocity) combined with an 8% increase in the price of nitrogen from $2,200/kg to $2,370/kg (Figure 4). Levers for Change Additional to the engineering investigations assessing options, Yarra Valley Water has also done a lot of other work that has assisted in the delivery of these projects. The additional work answers the uncertainty as to why a business would ever do such projects, and then accepting this, how they can be delivered. It covers integration of sustainability principles into business strategy, changing the business culture, and developing specific tools to overcome hurdles. Yarra Valley Water has integrated environmental sustainability into its core strategic operating principles. A business policy defines what it is, targeted actions exist in the business strategy, responsibility is allocated to business groups and individual performance plans, and performance is measured monthly and reported to both the Executive and the Board. Business culture has been improved by using the Human Synergistics process, which allows a preferred business culture to be identified, individual performance to be measured, and improvement actions to be identified (Jones et al., 2006). Yarra Valley Water has done this since 2001, over which time it has recorded a significant change, which has translated into individuals working more constructively together across the business and with other organisations. This is considered an important attribute to realising more sustainable outcomes, as sustainability essentially is seeking better outcomes across a broader scale of analysis, e.g. assessing the best outcome across the water cycle needs people to work across organisational work groups, different professions, and multiple organisations. It requires collaboration, which the change in organisational culture has provided individual enhanced skills to achieve. Seeking the most sustainable outcome has also thrown up many new challenges – for example, how to select the option that has the best environmental outcome, how to determine which option is the most sustainable, and how to ensure that the recommended option does not shift costs onto others and delivers the best community cost. For each of these Yarra Valley Water has developed and adopted specific tools and quantifiable methodologies. It uses life cycle assessment to determine the best environmental outcome; it has developed a multi-criteria analysis to assess sustainability, and has developed a community cost model to identify the best community outcome (Pamminger, 2009; Mathieson, 2011). outcomes Water utilities around the world today face a common challenge: how to provide water services to a growing Figure 4. Blackburn is an example of what is required to service an existing development in a more sustainable way; 2,200 properties are required if using stormwater for potable, 4,100 properties if sewer mining for non-potable, and 6,000 properties if sewer mining and stormwater were to be selected.
Water Journal February 2013
Water Journal November 2012-1