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Water Campaign™ case study

TOWN OF COTTESLOE, WESTERN AUSTRALIA

Cottesloe Peninsular Groundwater Restoration Project

: Community action

: Corporate action

: Partnerships

: Water quality

A print version of this case study is available to download. [PDF document, 430KB]

The Town of Cottesloe, Western Australia, is located in metropolitan Perth approximately 12 kilometres west of the Perth city centre, and has a population of 7411.

Council is participating in the Water Campaign™ as part of the Western Suburbs Regional Organisation of Councils (WESROC) and has been involved in the program since August 2006.

Synopsis

: Cottesloe Beach

The Town of Cottesloe has been working in direct partnership with the Australian Government, through the Water Smart Program, to implement a groundwater restoration project.

The Australian Government's Water Smart Australia Program aims to accelerate the development and uptake of smart technologies and practices in water use across Australia.

The project, which commenced in 2006, aims to restore the aquifer system under Cottesloe over a period of four years. The project will involve:

the replacement of 10 stormwater ocean outfalls with underground treatment tanks
the replacement of seven open sumps with underground sumps, utilising gross pollutant traps and a variety of commercial soakage systems
the installation of 400 stormwater kerbside soakpits leading to underground treatment systems to reuse stormwater for aquifer recharge.

Council will run a community education program to complement these works, aiming to increase knowledge and awareness in the community about water conservation, water efficient technology and sustainable gardening.

Residents and businesses will also learn how they can contribute to the sustainable management of Cottesloe’s groundwater resources.

In 2007 this project won the Town of Cottesloe the WA Water Award for Management of Water Resources by a Small Organisation.

Motivation

: A construction crew installs an infiltration system – Marmion Street

Groundwater management is a key issue in the Perth metropolitan region.

A lack of science and understanding of this crucial resource makes planning for sustainable use difficult and can lead to serious depletion due to over-consumption.

The Town of Cottesloe is located on a superficial freshwater aquifer, which is a major source of irrigation water for both Council and its community.

A freshwater lens that sits on top of saltwater, the aquifer is facing a range of problems related to groundwater quality and overuse. Consumption of the fresh groundwater coupled with reduced rainfall has led to an increase in salt content in the freshwater layer, potentially making it unsuitable for irrigation.

In addition, the highly permeable sandy soils typical of the area are susceptible to leaching of pollutants – such as fertilisers, hydrocarbons and heavy metals – through the soil profile and into the groundwater resource.

This is a particular problem at Cottesloe Beach, which experiences high visitor traffic throughout summer. Oil from cars builds up on nearby roads throughout the summer months, and is then washed into groundwater or the ocean by the first autumn rains.

Council’s 2003 Sustainable Development Plan identified the need to protect the coastal area’s natural beauty and biodiversity in order to maintain its reputation as one of the world’s best metropolitan beaches.

One strategy recommended increased funding for infrastructure to reduce stormwater discharge to the beach, while also recharging groundwater by diverting stormwater into the groundwater system.

With this strategic direction in place, Council decided to treat and infiltrate stormwater wherever possible. This means that the stormwater is being used to recharge the freshwater lens, whereas before it flowed directly into the Swan River or the ocean. The stormwater will also be of a better quality when it reaches the groundwater.

The support offered by the Australian Government and the Government of Western Australia further encouraged Council to develop this project.

Process

: Close up of plastic drainage cells – Marmion Street

The Town of Cottesloe applied for Round 1 funding under the Australian Government Water Fund in 2006 and received 30 per cent of the funds needed for the groundwater project. The former prime minister, John Howard, announced the successful grant in a 2006 visit to Cottesloe to launch the project just before works began.

Once funding from the Australian Government was received, Council then approached the Government of Western Australia’s Department of Water. The Department of Water has recently signed an agreement to provide $100,000 over three years to fund the project’s monitoring and education component.

Under the installation program for this project two sumps and 100 soakpits will be installed per year. By June 2008 up to 200 soakpits will have been installed, as well as five ocean outfalls replaced and three open stormwater sumps replaced with underground sumps.

Due to the amount of infrastructure required Council has been utilising a construction crew from a neighbouring council, the Town of Mosman Park. Mosman Park is also a member of WESROC and a participant in the Water Campaign™.

: Replacement of an open sump with an underground drainage sump – Railway Street

Fortunately, the selected soak pit structures are commonly used in the Perth area so the construction crew required no extra training. Installing underground storage systems – a relatively new concept to the area – required guidance from the supplier, which was provided at no extra cost.

The groundwater restoration scheme has been developed as a demonstration project to showcase the action that can be taken by a small coastal council, as well as displaying a range of new technology. For instance, the Town of Cottesloe has installed the first Iplex Aquacell system in Australia.

The project’s educational program will focus on both water conservation and the reduced use of fertilisers to protect the area's groundwater supply. The package, aimed at residents and landowners, will be delivered to every letterbox in the municipality and will include resources such as fridge magnets, pamphlets and bumper stickers. There will be an emphasis on educating children with a range of fun resources for kids.

As this is a demonstration project, once developed, the educational resources will be made available to all councils to use in education programs with their own council logo.

Savings and benefits

Water Management

The project will prevent approximately 180 megalitres of stormwater being discharged to the ocean each year.

Pollution samples will be collected as the project progresses and compared to those taken in mid-2007 by the Department of Planning and Infrastructure to determine the project’s impact on pollutant levels along the coastline.

The underground storage tanks will also allow stormwater to replenish and recharge the groundwater, helping to maintain groundwater supply and fight seawater intrusion.

In addition to this project Council continues to address its own consumption of groundwater through the Water Campaign™ and the development of a Water Conservation Plan. The Department of Water requires all Perth metropolitan councils to develop and submit a Water Conservation Plan, focusing on groundwater conservation through irrigation efficiency, by the end of June 2008.

Community Behaviour Change

The Groundwater Restoration Project’s education component encourages the community to contribute to sustainable groundwater management through minimising use of garden bores, reducing the number of new private bores installed and decreasing sources of private pollution such as fertilisers.

The program will also promote water efficient technologies, the use of alternative water sources, such as stormwater reuse, and sustainable gardening practices.

Stormwater management

: Cottesloe Beach - one of the world's best metropolitan beaches

Council has seen a marked improvement in areas susceptible to flooding since this project began. Strategically placed soakpits prevent a snowball effect during heavy rain events because stormwater is detained and infiltrated closer to the source rather than allowing it all to flow to a central location. This also minimises agitation and combining of pollutants in the water.

Council will also know exactly where all drainage components are located, as every installation will be plotted on a GIS database. This database will include information such as the construction details for plotted pits and where water flows.

A big advantage over traditional stormwater systems, this knowledge allows quick response to emergencies, such as pollution spills entering the stormwater.

A full-time GIS Technical Officer has been employed to input and manage data relating to the new infrastructure, collected and provided by the Works Supervisor.

Costs

The project will cost $2.34m in total. The Australian Government has contributed $782,000 and $1.56m was supplied by the Town of Cottesloe.

Council’s contribution is being funded predominantly through the annual road drainage budget, bolstered by the sale of a private property in Council’s ownership.

Purchasing and installing each soakpit costs $3500, and $100,000 for each sump. The remaining $240,000 will go towards transport, overheads and monitoring.

An additional $100,000, provided by the Western Australian Department of Water, will go towards the development of the education and monitoring program.

Lessons learnt

So far the project has progressed smoothly with a positive response from elected representatives, council staff and the community.

While kerbside soakpits are simple structures and easy to install, there is the possibility that concrete runoff from construction sites may cause blockages. Council will monitor this and undertake maintenance and cleaning as needed.

: Installation of underground drainage sump – Railway Street

Council is constantly reviewing the effectiveness of the utilised technologies and searching for ways to refine its approach to stormwater management.

During the construction phase there were significant rain events, enabling Council to identify areas that require additional capacity to manage floodwater.

The modular system of the soakpits means that it is straightforward to install further modules to increase capacity.

Having many small pits rather than a few large pits also makes it easier to upgrade the overall system.

As a demonstration project, Council is also committed to testing and demonstrating new technologies. As the installation program progresses and as upgrades are needed, Council will strive to implement the newest technology and will therefore need to stay up-to-date with the latest products on the market.

The key challenge for the future of this project will be changing community behaviour and attitudes towards sustainable water use, encouraging all residents and businesses to use water more wisely.

Further information

Australian Government Water Smart Australia Program website. In particular, see the Cottesloe project page

Town of Cottesloe website

Department of Water, Government of Western Australia website

Contact details

For further information about the ICLEI Water Campaign™ in Australia please contact:

ICLEI Oceania
4/267 Collins St
Melbourne Vic 3000
Ph:   +61 3 9639 8688
Fax:   +61 3 9639 8677
Email:   oceania@iclei.org
Website:   www.iclei.org/oceania/water

Acknowledgements

Thanks to Geoff Trigg, Manager of Engineering Services of the Town of Cottesloe, for his assistance.

Quoted Population figures are taken from the 2002 Australian Bureau of Statistics Report, 2000–01 Regional Population Grown: Australia And New Zealand.

Call for future case studies

Does your council have an initiative that could be promoted by the Water Campaign™ as a future case study?

We’d like to hear if your council has implemented an innovative water saving initiative or project to improve water quality. Contact your Water Campaign State Manager with details.

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