Banyule City Council: Stormwater Harvesting Project
Posted under: The Banyule Stormwater Harvesting Project incorporates stormwater treatment, harvesting and re-use infrastructure at three locations across the City of Banyule. These locations are Kalparrin Gardens in Greensborough, Chelsworth Park and Ivanhoe Golf Course in Ivanhoe, and DeWinton Park in Rosanna. Stormwater is harvested from main drains flowing through these sites from large suburban catchments.
Annually, the project will supply approximately 138 million litres of treated stormwater, replacing mains water, to irrigate over 30 hectares of sport and recreation open space. Additionally, over 240 tonnes of litter and other water pollution will be removed yearly as part of the stormwater treatment.
Description of Project
Banyule City Council’s $6 million Stormwater Harvesting Project will treat, harvest, store and distribute up to 138 million litres of stormwater. This sustainable source of water will replace the use of mains water, to irrigate parks and open spaces, benefiting the environment and the community and saving money.
While sport, recreation and open spaces are important for community health, wellbeing and connection to nature, they account for Council’s biggest use of drinking quality mains water. During times of drought, water restrictions resulted in open space going dry and dusty, losing grass and vegetation cover and becoming unusable.
With urbanisation, higher volumes of polluted stormwater run-off are undermining waterway health. Hundreds, if not thousands, of tonnes of litter, sediment and other pollution flow into Banyule creeks and rivers annually.
The project is close to the largest collection of stormwater harvesting infrastructure in metro Melbourne. This leading water sustainability project has the following objectives and anticipated outcomes:
- a more sustainable source of water yielding 138 million litres of treated stormwater annually to replace mains water for the irrigation of over 30 hectares of open space
- over $300,000 worth of annual water bill savings
- the removal of over 240 tonnes of litter, sediment and other water pollution annually from stormwater flows to the Plenty and Yarra Rivers
- improved environmental habitat for wildlife
These will be significant water sustainability outcomes for Banyule community and beyond, including Melbourne’s water supply situation and Port Phillip Bay’s ecological health.
The stormwater treatment, harvesting and re-use infrastructure are at the following three locations across the City of Banyule:
- Kalparrin Gardens in the suburb of Greensborough. Stormwater harvested here will irrigate Partingtons Flat, Whatmough Park and Greensborough Park.
- Chelsworth Park in Ivanhoe. Stormwater harvested here will irrigate Ivanhoe public Golf Course and Chelsworth Park’s six sports fields.
- DeWinton Park in Rosanna. Stormwater harvested will irrigate the oval at DeWinton Park.
This project is unique for Banyule and beyond – it is the first stormwater harvesting project that Council has ever done. It is distinguished by innovations focussed on the undergrounding of water storages and the precinct-scale distribution of water. In constrained urban areas such as Banyule, open space is at a premium. Over 15 million litres of water storage was built underground for the project, thus minimising the loss of open space. A particular innovation at Kalparrin is the ‘double-decker’ design, with a wetland and treatment zones on top of the storage.
Project construction has been completed and incorporates the following Water Sensitive Urban Design (WSUD) features:
- gross pollutant or litter traps
- sedimentation basins
- wetlands
- rain-gardens
(These features are for stormwater treatment, over 240 tonnes of pollution removal and improved environmental habitat.)
- over 15 million litres of water storage built underground with load-bearing scoria rock and other media wrapped in a waterproof geo-textile fabric – the scoria and other media void space is occupied by harvested stormwater. A bioactive film on the scoria removes nitrogen and phosphorous.
- harvested stormwater is pumped from the underground storages through a sand filter and ultra-violet disinfection gives one last clean to ensure public safety with the water irrigated on open spaces
The precinct scale of the project is another distinguishing feature. At Kalparrin, treated stormwater is distributed in pipes over about a kilometre to irrigate neighbouring Partingtons Flat, Whatmough Park and Greensborough Park. At Chelsworth, stormwater irrigates Chelsworth Park’s six sports fields and is piped over a similar distance to irrigate Ivanhoe Golf Course.
The most significant barrier faced by the Council was accurately costing the project. From concept to construction tendering, the project cost more than doubled due to the complexity and scale involved making it difficult for a definitive cost estimate. An internal commitment to project benefits and the external funding contributions helped overcome this barrier. Over $3 million of funding was secured from the Federal and State Governments and Melbourne Water to help pay for the project. Leasing tenants are making further contributions. This funding input is elaborated further in the ‘General Comments’ section below.
The multiple funding sources meant that project management was not only a significant engineering design and construction exercise, but also a significant exercise in stakeholder management. Project management had to deal with the complexity and interaction between the engineering and environmental objectives and delivering project benefits to earn adequate funding and buy-in from government, tenant, community and other stakeholder interests.
The project cost over $6 million for construction, design, project management, staff time and community engagement. Annual maintenance is expected to cost about $100,000. Annual mains water cost savings will be over $300,000, increasing with future water price rises. Over the anticipated 25-year (or longer) project lifetime, accumulated mains water bill savings are estimated at $15 million, easily eclipsing the project cost over that timeframe. If pollution removal, water utility and community benefits could be quantified in dollars, these would also be in the many millions of dollars.
This provision of more environmentally and financially sustainable water for open space irrigation is the main benefit to the community from this project. This project helps both community and Council minimise the impact of rising mains water costs along with providing a more reliable water source even with a possible return of an extended drought as a result of climate change. Drawing less on mains water which is better reserved for drinking and other more important use, this project’s water conservation benefit is integrated with a waterway ecology benefit with the removal of a large quantity of stormwater pollution.
Individual/Team Contribution
The Banyule Stormwater Harvesting Project was delivered by a range of personnel from a number of teams across Council, making it a ‘whole-of-council’ collaborative effort. Teams or individuals involved included:
- the Environmental Sustainability team with overall project development from concept, securing and managing over $3 million of government funding towards the project and managing community engagement and communications
- the Leisure and Recreation team with pursuing funding contributions from local partners and stakeholder management
- Parks and Operations team members with construction tendering and finalising project design by consultancy firm Fisher & Fisher
- the Major Projects team with project-managing construction by contractors Entracon, 2Construct and Evergreen
- the Communications team with project communications
- the Finance team with assisting project funds accounting and audit reports
- Parks and Operations teams with maintaining the project
The Major Projects, Parks and Operations teams are within the City Services directorate. Geoff Glynn, an IPWEA member, is the director of City Services.
All of Council’s four directorates are represented in the listing above and its unlikely the project would have been possible with that broad and in-depth involvement. This was especially necessitated by the scale and complexity of this project. A $6 million project such as this represents almost 10% of Council’s budget (excluding the ongoing staff salary and other benefits component of Council’s budget). Mobilising to manage a project representing one tenth of Council’s budget and being accountable to state and federal government agencies and a range of other stakeholders requires a big team effort and Banyule’s team delivered.
General Comments
The Banyule Stormwater Harvesting Project was driven by how badly open space fared in Melbourne’s drought last decade and by the Banyule’s City Plan policy direction to conserve water and improve stormwater quality.
Even more specifically, the project was also developed for the sustainability of two prominent Council assets – Chelsworth Park and Ivanhoe Public Golf Course. These assets cover about 24 hectares. They provide a revenue stream for Council in leasing arrangements with Ivanhoe Grammar School (IGS) and Leisure Management Services (LMS). With water restrictions during the drought, these assets were in crisis, emphasising how important water sustainability is for grass-based sport and recreation.
At its worst, it cost over $12,000 per million litres for trucked-in recycled water for irrigation – almost ten times the mains water price at the time. This lack of financial and environmental sustainability in managing these assets threatened the revenue stream for Council. Figure in trucked-in recycled water with price inflation, the 25 year accumulated savings of the stormwater harvesting project are estimated at $70 million.
There will be dry periods again and other water sources are getting expensive and this project prepares for this future. Council is leading by example with this project in a number of ways:
- it introduces a new, improved way to sustainably provide irrigation water in combination with pollution reduction
- it leads with its scale and delivery across precincts
- commencing in 2007, the project’s initial development stage pre-dates the shift of Federal and State Government policy focus on desalination to alternative water sourcing like storm and rainwater.
Leadership has also been demonstrated through the funding partnerships entered into for this project. Banyule and nine other councils in east metro Melbourne formed a consortium to secure Federal Government stormwater harvesting funding in 2010/11. Of almost $8 million of funding granted, Banyule secured the largest amount at $2.35 million.
There was further interest and funding from the State Government and Melbourne Water who contributed about $1.1 million. IGS and LMS are providing funding for the Chelsworth project.
For many Councils, open space irrigation is the biggest water user and water bills are growing due to expensive solutions like the state desalination plant. Stormwater harvesting is an increasingly popular approach for open space irrigation and pollution removal for a number of reasons. Stormwater harvesting:
- can be readily transferred and replicated by Councils and other open space managers.
- strikes the happy medium between the size of the available resource and the treatment required to make the water useable
- for example, stormwater that flows near open space – often located in floodplains or near large stormwater drains – is more plentiful and easier to access than roof rainwater
- requires less treatment than seawater desalination or sewage recycling, which are much more energy intensive.