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House of Assembly - Fifty-First Parliament, Third Session (51-3)
2009-12-02 Daily Xml
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STORMWATER RE-USE

The Hon. S.W. KEY (Ashford) (14:35): Will the Minister for Water Security advise the house on the recent scientific advice regarding stormwater use?

The Hon. K.A. MAYWALD (Chaffey—Minister for the River Murray, Minister for Water Security) (14:36): I thank the honourable member for her question and I appreciate her interest in these matters. There can be no matter of higher importance to any government than ensuring the safety of public drinking water supplies. The government is serious about understanding stormwater re-use quality risk factors and how they might be managed. This government has provided significant support, including through the Premier's Science and Research Fund, for research into aquifer storage, transfer and recovery.

This world-first research project has been undertaken at a site in the City of Salisbury in collaboration with United Water, the CSIRO, the City of Salisbury, United Water and SA Water, with technical support from the Department of Water, Land and Biodiversity Conservation and with support from the Adelaide and Mount Lofty Ranges Natural Resources Management Board. The project is also supported by the commonwealth government.

I am advised that state funding and in-kind contributions total approximately $535,000, which includes $350,000 from the Premier's Science and Research Fund. Furthermore, the total value of all contributions, including those from the CSIRO, the commonwealth government and United Water, exceeds $4.2 million.

Several reports have been published on this research project, and technical presentations on the findings were made to industry representatives on 28 September 2009. It is very clear from the research that wetland and aquifer storage, transfer and recovery, by themselves, cannot guarantee that the water will be of drinkable quality.

In fact, on 10 October 2009, Professor Peter Dillon, a leader in research into water recycling and diversified supplies at the CSIRO, wrote to me about this research project. In his letter Professor Dillon made the following very clear point:

…we cannot say that we have produced water capable of use as mains water because the risk assessment for the potential hazards and the preventative measures to protect water quality have not been defined. The impacts of the recovered water on mains infrastructure has not been evaluated and the aesthetic qualities of recovered water in distribution systems have not been addressed.

Professor Dillon continues:

The full range of options for stormwater use, including as non-potable supplies alone or in conjunction with recycled water and as drinking water via dams and treatment plants, all with and without aquifer storage, would provide a much firmer basis for government decisions concerning options.

The CSIRO's report of the operational residual risk assessment for the Salisbury stormwater ASTR project provides further valuable insights into risk factors. The report is publicly available. It indicates that two reference pathogens used in controlled evaluation studies, cryptosporidium and rotavirus, were relatively slow to die off in the aquifer and that post-treatment would be needed to manage the risk.

The report also comments on the other potential risks. Several of the points made by the CSIRO in its report include:

The subsurface storage and transfer aspect of the ASTR scheme is not advanced enough to fully evaluate the residual risk from inorganic chemical hazards. This preliminary risk assessment suggests that there is a residual risk of iron exceeding Australian drinking water aesthetic guidelines unless further treatment is considered.

The arsenic concentration in the ambient groundwater is sufficient to indicate a source of arsenic within the aquifer sediments that can lead to increased concentrations through managed aquifer recharge.

There is potential for arsenic mobilisation during aquifer storage via two possible mechanisms.

The results to date indicate that the risk is not well defined for arsenic but is unacceptable for iron based on the aesthetic water quality guideline value. There is little data available to assess the production of turbidity and impact on the quality of recovered water. The residual risk for turbidity cannot be fully defined without additional evaluation of the capacity of the aquifer as a treatment step for turbidity and particulates.

The report expresses a need for further research and investigative studies to identify and characterise potential hazards and to fill knowledge gaps. I have previously indicated to the house that there is currently insufficient understanding of the risk factors, and this is borne out by the CSIRO's research.

The quality of urban stormwater run-off from roads can be highly variable in quality. It can contain litter, silt, animal droppings and dissolved chemicals such as detergents, fertilisers, hydrocarbons and heavy metals. It could contain harmful micro-organisms such as bacteria and viruses. Urban stormwater can be highly variable in quality which makes the task of managing it challenging, especially for potential drinking water use. There may also be potential hazards associated with the storage of wetland treated stormwater in natural ground water systems which need to be properly understood.

The state government's Water for Good strategy articulates that augmenting public drinking water supplies with highly treated stormwater cannot proceed without appropriate understanding of the risk and confidence that they can be managed without the knowledge of significant net public benefits, especially when this type of recycling is compared to other available options such as continued use of stormwater for non-drinking purposes such as continued use of stormwater through 'third pipe' systems. There needs to be strong community support for the option.

The government is highly committed to capturing and using stormwater and using it for appropriate purposes. In Water for Good we have committed to capture up to 60 gigalitres the year of stormwater in greater Adelaide by 2050. Water for Good is informed by the Urban Stormwater Harvesting Options Study, undertaken by Wallbridge and Gilbert, which provides objective evidence of the potential for large-scale capture and storage of stormwater across Adelaide.

Water for Good actions to promote stormwater use include developing a master plan to manage stormwater in Adelaide effectively, continued support for world leading research to assess the potential for treating stormwater to a very high quality and monitoring of scientific developments and technological innovations. The government is a major contributor to stormwater harvesting projects underscored by South Australia's successful bid for commonwealth funding with $150 million for projects across metropolitan Adelaide. The state government has committed about $45 million to these projects which, along with other projects, will triple our stormwater harvesting capacity from the current 6 billion litres to more than 20 billion litres by 2014.

The commonwealth is also supporting projects with its contributions including: $20 million for Water Proofing the West Stage 1; $14.97 million for Water Proofing the South Stage 2; $9.6 million for the Playford Stormwater and Re-use project; $6.99 million for the Unity Park Biofiltration and Re-use project; $4.864 million for the Adelaide Airport Stormwater Scheme; $3.925 million for the Barker Inlet Stormwater Re-use Scheme project; and $2.935 million for the Adelaide Botanic Gardens First Creek Wetland ASR project. The City of Unley was also successful in receiving $2.558 million from the commonwealth to fund its own stormwater harvesting and re-use project.

It is worth noting that the response from South Australia to the Australian government's special call for stormwater projects was stronger than in any other state, with nearly half the total number of applications coming from South Australia. We lead the nation in stormwater and waste water recycling. Our projects very clearly demonstrate the state government's commitment to diversifying our water supplies from desalination (our climate independent source of drinking water) to recycle stormwater and waste water to provide a non-potable alternative and to reduce reliance on the River Murray. What we will not do is put the wellbeing and safety of South Australians at risk by rushing blindly to introduce stormwater into our drinking water until we are certain that in doing so we will not compromise the quality of the water or endanger the health of South Australians.

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