Storm-water from the East Geelong drainage system is captured and stored in the Eastern Park dam. It is then filtered and treated for use in the Botanic Gardens.
Stormwater from the East Geelong drainage system is captured and stored in the Eastern Park dam, which is then treated and used for irrigation in the Botanic Gardens, and tree watering around Geelong.
Using recycled water reduces the Botanic Gardens reliance on drinking water. This stormwater harvesting system supplies over 70% of water used for irrigation in the Botanic Gardens, saving over 15 million litres of drinking water each year.
Location in Eastern Park
The water storage dam is located in the southern part of Eastern Park, in the same location as a small lake used to be up until 1925 when it was filled to create a cricket field.
How does it work?
Water is diverted from the stormwater drain, through a gross pollutant trap which collects pieces of rubbish down to 5mm in size, and then into the storage dam. It holds approximately 4 million litres and takes up an area of approximately 7000 square metres. A wide selection of terrestrial and aquatic indigenous plants were planted around the water's edge to assist in the water cleaning process by removing and using nutrients such as nitrogen and phosphorous.
When water is required for irrigation in the Botanic Gardens, water is drawn from the dam and is passed through filtration tanks, then sterilized using ultraviolet light, before being transferred to the gardens irrigation systems.
From the water’s edge the slope of the batter is gradual for 10 metres before reaching a maximum of 2 metres deep when full. The edges of the dam have been designed to Royal Surf Lifesaving Guidelines to have a gradual slope. Plants create a physical barrier to deter people from getting into the area.
The system is designed to only draw off the top 1 metre for re-use. Water will always be in the dam unless we have abnormally long dry periods. When this happens the natural evaporation can dry out the dam.
Where will the water come from?
The catchment area for this system is a 47 hectare suburban area of East Geelong. Storm water flows into the existing stormwater pipes and is diverted into the stormwater harvesting system instead of flowing into the open concrete channel, between the East Geelong Golf Club and CSIRO. Being an older suburban catchment the stormwater quality is very good.
Mosquitoes thrive in stagnant and shallow water. This system has been designed to replenish itself approximately 20 times a year. Therefore the water will be constantly turned-over with new stormwater supplies.
The water is shallower around the edges for safety but most of the water is too deep for mosquito breeding. The site has been added to Council’s sites to monitor for mosquito populations and will be treated if required.
Project funding and timelines
The Australian Government’s Water for the Future initiative contributed $415,000 and the City of Greater Geelong $515,000 to this $930,000 project.
Construction work commenced in October 2011 and was completed in March 2012. Planting of indigenous plants was carried out from June to October 2012, and the system started supplying water for irrigation November 2012.