News & Events

Water Sensitive Urban Design in Melbourne, Australia – a personal view Posted: 06/02/2009

 By Richard Ashley

There has been something of a ‘sea change’ in water management in much of Australia in the last year. Following some ten years of drought and significant progress in demand management, with most domestic consumers reducing their usage to less than 200 litres/hd/d, the politicians have found a ‘magic wand’: desalination plants. These are being constructed in almost every major urban conurbation across Australia apart from Brisbane. In Melbourne, which will have the largest plant producing 150 Gl by 2011, the (public-private-partnership) scheme will double water bills. Melbourne Water as wholesaler are contracted to purchase water from the private supplier for some 15 years; the water is then supplied to consumers by 3 water retailers. The supplier organisations are corporately owned by the Victoria State Government and return profits each year. One of these is Yarra Valley Water (YVW), which has the largest catchment of the city.

I was invited by YVW to run a workshop on assessing sustainability.   Their consensus view was that the Victorian State Government were seeking the ‘easy way out’ ,which would lead to further climate degradation by high energy use.  At best such a plant would allow a 15 year window to really sort out the water supply problems.  Concern was voiced that the Government misleadingly presented a distorted case for desalination by lying about the true costs.

Components of the Kalkallo water/wastewater system are shown below

 Rainwater storage

Rainwater

Lot scale tanks (3.5kL & 10kL)

Communal scale tanks (40kL)

Development scale (15ML)

Diverted and treated at Yan Yean

 

 

 

Stormwater

 Stormwater

 

Communal scale tanks every 10 lots (50KL)

Development scale tanks (15ML)

 

YVW’s approach for SA for water and wastewater management was illustrated for Kalkallo, a proposed 1180ha Industrial & Commercial Development on the northern boundary of the city.  Options included the following and other combinations: conventional piped systems with centralised treatment; rainwater tanks on every property; rainwater tanks on each property and communal stormwater storage tanks topped up with imported reclaimed water; 3rd pipe with reclaimed stormwater backed up with imported reclaimed effluent; development scale capture and treatment of roof runoff, distributed via potable network plus imported recycled effluent distributed via third pipe system.

Their sustainability assessment was based on the ‘SWARD’ and other criteria, monetised into equivalent Australian dollars. The main principles were seen as the need to try to work across the entire water cycle, instead of considering supply, stormwater and sewage as separate factors. The costs were distorted due to the forthcoming desalination supplies, which will actually treble the unit cost of water.

Best options comprised the use of a third pipe with local sewage treatment plant and stormwater harvesting and treatment for potable substitution. These are all acceptable to the regulators. However, in discussion it was apparent that the decision criteria had been defined internally by the main water service providers, without including potential developers or the community. In addition, there had been little scenario planning considering the potential rapid changes in climate and socio-economics during the 30-100 year lifetime of the development.  Adaptability, resilience and flexibility were thus not considered. There was little effort to adopt ‘social learning’; i.e. building the capacity in the public and others to engage in future changes, and to be able to cope with them.

Other issues raised were the relative incompetence of both the economic and environmental regulators in Victoria, neither of whom were perceived to understand ‘sustainability’ and who actually promote environmentally damaging schemes because of an unwillingness to take a whole-system performance approach.  Following this, at a meeting with the Managing Director, Tony Kelly, it was concluded that YVW needed urgently to appoint social scientists to help them with their internal culture to be better prepared for and engaged in the social learning that is required to change behaviour and attitudes to water if the future challenges are to be met.

 

Recycled from Sewage Treatment Plant

Recycled water

 

Supplied from Mt Ridley when stormwater not available