Blackmans Swamp Creek Stormwater Harvesting Scheme
Delivering the Project
The Blackmans Swamp Creek Stormwater Harvesting Scheme represents the first large scale, indirect-to-potable stormwater harvesting project in NSW, if not Australia. This project is capable of providing between 1300-2100ML of additional water into the Orange’s raw water supply each year from the city’s stormwater system, meeting up to 40 per cent of the city’s total water needs.
The first release of harvested
stormwater flows into Suma Park
Dam on 21 April 2009
This project has evolved from concept to operational reality within 18 months at a cost of $5 million involving extensive consultation with the community and government authorities and detailed analysis to satisfy concerns about the safety, reliability and capacity of the scheme.
Orange’s water storages typically receive the majority of inflows at the end of winter/early spring when supplies are replenished. Suma Park Dam last spilled in late 2005, however continued dry conditions over subsequent years and well below average runoff resulted in the city’s water storages dropping to levels never previously encountered. By late 2007 the storages were below 40% and forward rainfall projections were less than positive. At their lowest levels in August 2008 the storages reached 26.7.%
In response to this challenge, Council's Technical Services Division began investigating a range of options aimed at both reducing water consumption within the city as well as investigating opportunities for augmenting supplies. At the outset, the approach taken was not just to apply a short term solution to get through the current emergency in the hope that it would rain again and the problem would go away. In contrast, it was recognised that a much more strategic solution was necessary.
Included in this has been a package of demand management and system operating solutions such as best practice pricing, water restrictions, education programs, water loss remediation strategies, working with high water users to reduce their water use and installing water efficient devices across the city.
As a consequence of these and other initiatives, water usage in Orange dropped to less than 4390 ML in 2008, a drop of around 38% from the high of 2002.
Construction of the 200 megalitre
holding dam - 11 November 2008
A range of measures were also investigated during this time with the aim of sustainable augmentation of the city’s water supply. These included groundwater investigations and re-connection to the city’s old water supplies. In addition, the harvesting of stormwater emerged as a viable option worthy of detailed investigation.
The basic concept of the Blackmans Swamp Creek Stormwater Harvesting Scheme involves capturing a portion of the high flows in Blackmans Swamp Creek during storm events, and transferring these into the nearby Suma Park Dam to augment the city’s bulk water supply. A number of key elements make this system viable.
These include the close proximity of Blackmans Swamp Creek to Suma Park Dam, the availability of key existing infrastructure and the very high level of treatment provided by Council’s main water filtration plant at Icely Road, which treats the raw water from Suma Park Dam. This includes ozone treatment to destroy pathogens and Biologically Activated Carbon Filtration to consume the remnants of the compounds destroyed by the ozone. The regularity of flows in Blackmans Swamp Creek was also a key element. Because of the large impervious areas in the catchment, reliable runoff occurs after every rainfall event.
A key tool to assist in the consultation process has been the development of the Review of Environmental Factors (REF) for this project, which includes a series of operating rules to provide a clear outline of how the project will work. These involve establishing flow trigger points when harvesting can commence, maintaining base flows, and establishing ongoing stakeholder engagement once the project becomes operational.
The stormwater release point
into Suma Park Dam
- 21 April 2009
The REF provides a comprehensive outline of the project, neatly summarising thousands of pages of analysis as well as clearly determining that the project will not cause undue impact to the downstream environment. On the contrary, the work actually improves the existing situation through the removal of suspended solids via a series of Gross Pollutant Traps (GPTs), as well as reducing peak flow levels, thus reducing the likelihood of erosion and damage during high flow events.
A critical issue throughout the development of this project has been the need to ensure the harvested stormwater meets the appropriate standards of the Australian Drinking Water Guidelines. This is achieved through the creation of multiple barriers within the water supply system to eliminate possible contamination. Council has worked closely with key State authorities, such as NSW Health, the Department of Environment and Climate Change (DECC) and Department of Water and Energy (DWE), including conducting a two day Hazard and Critical Control Point Analysis (HACCP) workshop with representatives of these and other agencies.
The public reaction to drinking harvested stormwater was also tested through a series of community consultations, including on-line surveys where the predominant response was not one of concern about water quality but of urging Council to get on with the work as soon as possible.
The first stage can deliver 1300 megalitres annually. Orange’s long term average water usage has been around 7000 megalitres a year. However in recent years, thanks to efficiency measures and education programs, this has fallen to below 5000 megalitres annually.
Council has broken new ground in the development of this large scale, direct-to-potable stormwater harvesting project. Given the current focus on innovation in managing the security of urban water supplies, it is the right project for its time. It has been developed from idea to reality within a very short space of time while giving proper consideration to the necessary legislative, environmental and community consultation processes. The project demonstrates that with support, local government can use local resources to solve local problems.
The Scheme was officially opened by The Hon Phillip Costa MP, NSW Minister for Water on 27 August 2009.