Maintaining numerous world-class sporting fields and extensive surrounding reserves requires significant amounts of water for irrigation, which can be costly, environmentally damaging and difficult to sustain in times of drought. Blacktown City Council overcame these issues with the innovative Angus Creek stormwater harvesting and reuse scheme.

The Blacktown International Sportspark in Sydney is an elite international sporting facility that hosts over 5,000 events and 750,000 visitors per year. Originally developed as a major playing and training venue for the 2000 Sydney Olympic Games, the sportspark has continued to grow and develop in the years since.

In order to maintain the park and its numerous sporting fields, substantial volumes of water are required for irrigation. Blacktown City Council needed a sustainable water source that would improve both drought resilience and the condition of local waterways, and also be financially viable and carbon neutral.

The Angus Creek stormwater harvesting and reuse scheme (the scheme) was developed to make use of the excess stormwater flows from nearby Angus Creek, as well as the runoff from hard surfaces throughout the sportspark. This water is then used to irrigate the sportspark and neighbouring reserves.

Using a combination of multi-functional design and self-financing governance models, the scheme is believed to be the first stormwater harvesting scheme of its type in New South Wales that captures full water savings.

Ensuring drought resilience

A key aspect of the scheme design was reducing the need for potable water — even under potential future water restrictions during drought periods — which was achieved by having three storage ponds form the scheme’s main water storage. These storage ponds serve a dual purpose: storing up to 8ML of stormwater while also acting as flood detention basins for the sportspark.

The storage ponds also incorporate floating wetlands, which provide stormwater treatment as the suspended solids are given time to settle while the water is moving through the ponds. The floating wetlands then treat the stormwater through the biological uptake of nutrients present in the water, making it suitably treated for irrigation purposes while mitigating any public health risk by reducing the establishment of algae.

By harvesting and treating stormwater, the scheme reduces the need to use potable water for low risk end uses, such as spray irrigation, by generating its own reliable, fit-for-purpose water.

To combat the issue of blockages within the storage pond pump station, a mesh litter basket was implemented. It was found that small wildlife (mainly snails and gambusia) and some algae stands were finding their way into the pump station, causing blockages in the downstream screen filter. This also meant that the screen filter required higher frequency manual cleaning.

The 200 micron mesh in the wetland pit collects and stores the algae and animals, while providing a much greater surface area and infrequent maintenance compared to the screen filter.

Minimising the environmental impact

Improving the local waterways and surrounding environment was imperative to the scheme and was achieved through an innovative project design.

The 655-hectare catchment generates about 2,000ML of runoff each year. Extracting excess flows above 10L/s and reducing the amount of stormwater in the creek has decreased the overall pollutant loads downstream of the extraction point, while reducing creek bank erosion and stress on aquatic ecosystems that are sensitive to large and frequent flows.

The scheme also implemented a commonly used technology in drinking water treatment — the SCADA system. This technology collects and analyses real-time data about water quality and quantity, which is then used to control the pumping and treatment systems. The SCADA system uses multiple online water quality monitoring points, collecting and measuring turbidity, oxidation-reduction potential (ORP) and electric conductivity, which are used as critical control points that can turn off pump switches, preventing the system from harvesting water that is not suitable for irrigation.

One of the issues encountered during the wetland establishment phase was the large water bird population, as they were reaching the bottom of the wetland and removing plants. To combat this, water levels were increased. Although this slowed plant growth rates and prolonged the establishment period, it made it significantly more difficult for the
water birds to remove the plants.

Additional measures were put in place to reduce the environmental impact of the scheme, which includes a 40kW solar system to offset the electricity used by the pumps and treatment measures — making the scheme carbon neutral. Macro-invertebrate analysis and water quality monitoring also provide valuable data for long-term environmental management.

Self-funded and financially sustainable

Perhaps the most impressive aspect of the scheme is that it is financially sustainable. The scheme is self-funded, with the harvested stormwater sold to water users at the same cost as potable water. The funding generated reduces the need for other sources of revenue to fund ongoing operation and maintenance costs and also allows for the employment of a Stormwater Harvesting Officer to oversee the project.

However, approvals to extract water and construct creek works are difficult and can challenge a project’s viability. There were many challenges in acquiring approval to divert water from the creek into the offtake dam, but the NSW Office of Water provided an exemption to Blacktown City Council from purchasing the 200 water unit shares that were initially required, which was enormously important in ensuring the project’s financial viability.

Suitability for other areas

While the scheme is transferable to other high-end open space and recreation facilities where irrigation demands are high, it would be particularly applicable to areas where an adjacent waterway can be drawn upon for water supply, and where the adjacent waterway is subject to urban excess flows or otherwise where large catchment flows can be captured for stormwater harvesting.

Governance regarding the creek extraction and construction works may be a limiting factor, as was nearly the case for this project. Another major factor that could limit other projects is the limit set for stormwater harvesting. The Angus Creek scheme can only harvest stormwater during rainfall events or when flow is above 10L/s, which was a requirement from the NSW Office of Water.

This requirement affected the design of the scheme, and resulted in the inclusion of additional components including, large pumps to maximise fast extraction, large water storages able to hold six to eight weeks’ worth of irrigation and treatment measures capable of handling higher turbidity loads associated with storm flows.

The scheme has caught the attention of many for its innovative and sustainable design, and was highly commended at the 2016 IPWEA Awards for Excellence in Environmental Enhancement Project of Initiative including Recovering, Recycling and Reusing. In 2018, the scheme won a Stormwater NSW Excellence in Infrastructure award and was highly commended by Stormwater Australia under the same category.

More recently, the scheme received a certificate of commendation as part of the Greater Sydney Commission’s planning awards great sustainability initiative, awarded by Lucy Turnbull.

Charlotte Pordage is Editor of Utility magazine, a position she has held since November 2018. She joined the team as an Associate Editor in October 2017, after sharpening her writing and editing skills across a range of print and digital publications. Charlotte graduated from Royal Holloway, University of London, in 2011 with joint honours in English and Latin. When she's not putting together Australia's only dedicated utility magazine, she can usually be found riding her horse or curled up with a good book.

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