Parafield Stormwater Harvesting Facility

What is stormwater?

Stormwater is water that runs off surfaces such as roofs, roads, footpaths and driveways when it rains. Much of this water flows into stormwater drains and then into creeks and rivers, eventually making its way into the sea. At present, about 160,000 million litres of polluted stormwater is released into Gulf St Vincent each year, much of it into the Barker Inlet.

Why does stormwater pollution matter?

Barker Inlet has a diverse, yet vulnerable ecology including a population of dolphins. The quality of stormwater directly affects the health of this important ecosystem.

Stormwater is also used for several Aquifer Storage and Recovery sites, which act like large-scale rainwater tanks. During the wet season, stormwater is filtered using natural wetland processes and injected underground into porous rock. It is recovered to provide water for community purposes such as watering parks and sporting fields and for local business and industry.

Stormwater is a valuable resource that is important for a number of different reasons. By stopping stormwater pollution we contribute to making our community more sustainable and we can continue to enjoy the natural environment we live in.

The Barker Inlet

In the 1990's the City of Salisbury defined a vision that it would seek to eliminate the flow of polluted water into the marine environment of the Barker Inlet of Gulf St. Vincent. The Barker Inlet is a delicate marine environment of mangroves and sea grass meadows serving as a nursery for a majority of the State's fishing industry. However, years of neglect and polluted inflows have reduced the Barker Inlet to a delicate state.

The creation of wetlands to cleanse stormwater was Salisbury's key strategy to help the ecological rehabilitation of the Barker Inlet while providing cheaper water to local industry and other users.

Stormwater is treated and harnessed in a series of more than 30 wetlands along urban stormwater paths to slow the flow and allow pollution to settle out. The wetlands cover an area of 260 hectares enhancing the landscape and creating habitat diversity.

All the wetland plants are propagated at the Council's nursery and they play an important role in the treatment of polluted stormwater. The nursery has developed a high level of expertise in propagating various wetland species, and it sells wetland plants to users all around Australia.

Parafield Stormwater Harvesting Facility

The Parafield Stormwater Harvesting Facility originated from a discussion in 1999 between City executives and the management of G. H. Michell & Sons, Australia's largest wool processing company.

The company's processing involves the use of 1100 million litres per year of mains water to wash the wool, which in turn produces large quantities of effluent and sludge. The costs of fresh water and sewerage disposal were high enough to force the company to consider alternative, cheaper locations elsewhere, potentially resulting in the loss of around 700 local jobs.

The Parafield stormwater project involves diversion of stormwater via a weir in the main Parafield drain to a 50 million litres capacity capture basin. From there, it is pumped to a similar capacity holding basin, from where it gravitates to a two hectare cleansing reed bed.

Nutrient and pollutant loads are typically reduced by up to 90 per cent and the treated water salinity is less than 250 mg/L. The system is designed to hold stormwater for around 10 days to ensure optimal treatment efficiency.

The current supply capacity of the scheme is 1100 million litres per year. The second stage would add other catchments and boost the supply to 2100 million litres per year.

Continuity of supply is gained through the creation of large underground storage of treated stormwater. This is achieved by the development of an Aquifer Storage and Recovery (ASR) system. Two ASR bores (depth 180 metres, T2 Aquifer) have been installed allowing supply when the system has no flow. The recharge water quality has to meet the Environment Protection Authority (EPA) requirements.

Through the project, G.H. Michell & Sons will receive water with a salinity (TDS) of 250mg/L, which is significantly lower than the salinity of water from the River Murray (> 400 mg/L). The ASR project will foster the growth of new and established industries, especially those with high water quality requirements. Prospective employment opportunities in the region will be subsequently increased.

Investing in the Future

The City of Salisbury's investment in a unique and diverse series of wetlands has significantly enhanced the amenity and environment, and contributed to the social well being of the community. Projects such as the Parafield Stormwater Harvesting Facility are a great way to deliver on the triple bottom line of sustainable environment, economy and community.

These projects will help to catalyse a paradigm shift among regulators, industry and community in recognising the enormous potential of stormwater as a valuable and sustainable resource. Importantly, they serve as a blueprint in urban stormwater management for other communities.

For further information, download the Stormwater Harvesting and Utilisation in the City of Salisbury brochure (479 kB).

To download this document you will require Adobe Acrobat Reader. The size of the document is indicated next to the link.