Stormwater harvesting

The City of Casey is leading by example in sustainable urban water management.

In 2009, the City of Casey undertook three stormwater harvesting projects to reduce demand on potable water, improve the security of the municipality’s water supply, and reduce the impact of urban run-off on Casey’s waterways and wetlands.

Stormwater harvesting is the collection, treatment, storage and re-use of stormwater run-off from urban areas. It complements other approaches to water conservation such as restrictions, rainwater tanks and the use of greywater, but is different in that it captures water from urban infrastructure like roads and drains.

Casey’s open spaces are important to the community for liveability, amenity and well-being. In recent years, diminished water supplies and restrictions due to drought have posed challenges for irrigating reserves and, in particular, sporting fields. Harvested stormwater can be used instead of mains water to keep sporting fields green.

Council has effectively drought-proofed three of its most popular open spaces by constructing stormwater harvesting systems to maintain sporting fields at Grices Road Reserve, Edwin Flack Reserve and Sweeney Reserve. The projects were staged over three years, with the City of Casey and the Federal Government investing more than $1, 970,628. These stormwater harvesting projects will:

  • save up to 39 million litres of potable water per annum
  • reduce pollution running into Casey’s waterways
  • secure Casey’s future water supplies.

Grices Road Reserve

The Grices Road Reserve stormwater harvesting system is one of Casey’s initiatives towards becoming a water sensitive city – a city that responds appropriately to climate change and water restrictions.

Background

Located in Berwick (Melway Ref. 131 B7), the reserve has three soccer fields and is popular with the Casey community; including more than 460 people involved with the Berwick Springs Cricket Club and the Berwick Regional Churches Soccer Club. It was identified as one of the sporting reserves that accounted for a significant proportion of Council mains water use. The site was selected for a stormwater harvesting system so that the sporting fields could be preserved in drought conditions.

Design

Melbourne Water’s Ti- Tree Creek wetland near Grices Road Reserve is a 199 hectare urban catchment area for stormwater run-off. By agreement with Melbourne Water, the reserve’s stormwater harvesting system draws water from the Ti Tree Creek and Grices Road Reserve car park through a pollutant and litter trap and stores up to 300,000 litres underground. In order to minimise any risks to human health, the water goes through an ultraviolet disinfection process prior to use for irrigating sporting ovals.

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Rain garden

The City of Casey included an additional Water Sensitive Urban Design (WSUD) element by constructing rain gardens near the reserve’s car park to further improve water quality before it reaches the underground tank.

Rain garden

A rain garden is a vegetated garden bed that helps stormwater runoff to filter through layers of soil and then slowly soak into the ground. These layers assist in the removal of pollution washed off hard urban surfaces, such as nitrogen and phosphorus, fertilisers, dust, leaves and animal droppings. Rain gardens are very effective in improving water quality and can cut down the amount of pollution reaching waterways.

The rain gardens at Grices Road Reserve create a healthier environment and visual amenity for users of the reserve.

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Caption: Rain Garden at Grices RoadReserve.

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Caption: An underground tank under construction at Grices Reserve.

The overall capital cost of the scheme was $390,508 (GST exclusive).

In operation since June 2013, the stormwater harvesting system can supply the reserve with up to 12 million litres of water per annum.

Edwin Flack Reserve

The stormwater harvesting system at Edwin Flack Reserve is another project that demonstrates the City of Casey’s commitment to creating a sustainable and liveable city.

Background

The Edwin Flack Reserve was named in honour of Australia's first Olympian and is located in Berwick (Melway Ref. 111 H7). The reserve features a football oval with a cricket pitch, and an athletics track. It is an important recreation resource for the community, including the neighbouring Berwick Secondary College.

Design

Stormwater run-off from a residential catchment enters a Melbourne Water stormwater drain near the reserve. By agreement with Melbourne Water, the City of Casey captures some of this run-off and treats it through a gross pollutant trap and rain garden.

Gross pollutants trap

Gross pollutants traps are structures that trap solid waste such as litter and coarse sediment. They are commonly the first treatment stormwater undergoes because they remove non-biodegradable large pollutants such as litter and sediment. By removing large pollutants, downstream treatment of stormwater can happen more easily. 

The gross pollutant trap and rain garden removes significant amounts of pollutants (for example, litter, suspended solids, nitrogen and phosphorus) from the run-off water before it is stored in a 500,000 litre underground tank. Prior to use, ultraviolet light is applied to the water to disinfect it.

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The stormwater harvesting system at the Edwin Flack Reserve can supply up to 6 million litres of water each year. The construction of the stormwater harvesting system at Edwin Flack Reserve was completed in June 2013.

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Caption: Rain garden at Edwin Flack Reserve

The overall capital cost of the scheme was $497,416 (GST excl.)

Sweeney Reserve

The Sweeney Reserve stormwater harvesting project is the City of Casey’s largest and demonstrates Council’s commitment to innovative water management solutions.

Background

Sweeney Reserve in Narre Warren (Melway Ref. 110 E7) is an open space highly valued by Casey residents. Before the construction of a stormwater harvesting system, maintaining it required large volumes of potable water.

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Caption: Excavation works for the construction of a stormwater harvesting system at Sweeney Reserve

Design

Stormwater run-off from a residential catchment enters a Melbourne Water storm-water drain and, by agreement with Melbourne Water, the City of Casey captures some of the run-off and treats it through leading edge WSUD features, including a sediment pond and rain garden. Considerable amount of pollutants are filtered out as the runoff passes through these features. Treated water flows into an open storage pond that can hold up to six million litres. Before it is used for the irrigation of sporting ovals, ultraviolet light is applied to the water to disinfect it.

Water Sensitive Urban Design (WSUD)

WSUD is a critical part of the planning and design of urban environments. It minimises the impacts on waterways of stormwater run-off from urban infrastructure by mimicking the natural water cycle as closely as possible.

The open storage pond has a valuable environmental role and is a welcome addition to Casey’s network of wetlands.

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Completed in June 2013, the system can harvest and re-use up to 21 million litres of stormwater each year to irrigate sporting facilities at the reserve, including football ovals, soccer and softball fields. The overall capital cost of the project was $1,081,159 (GST excl.).

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Caption: Aerial image showing three stage design of stormwater harvesting system at Sweeney Reserve. Anti-clockwise from the bottom: sediment catchment pond for water coming directly from Melbourne Water’s drains: rain garden to remove gross pollutants; storage pond at the top. Walking paths for recreation can also be seen.

The City of Casey’s stormwater harvesting projects enhance amenity and recreational opportunities for the community and have an important place in Council’s vision for an environmentally sustainable city that uses water wisely.