Edinburgh Gardens Raingarden
A raingarden was officially opened in Edinburgh Gardens in October 2011.
Built with the support of Melbourne Water, the raingarden is a water harvesting system that provides a natural irrigation source for Edinburgh Gardens. The raingarden is expected to supply 50% of the water needed for the park's historic trees.
The raingarden filters stormwater and rainwater and collects it in an underground tank. Water from the tank is then used to irrigate the park.
The raingarden will also help improve the health of Merri Creek and the Yarra River by filtering pollutants from captured stormwater.
Initially, a wetland was proposed but site investigations found a raingarden to be a more compact and less costly solution for treating stormwater runoff.
The raingarden occupies about 600 m2 on the site of the demolished Ladies Bowling Club within the southern section of the park (between the tennis courts and the grandstand). It consists of four terraced gardens of native plants. Near the raingarden, Lemon Scented Gums and Angophora trees were planted to create a new avenue.
Rectification works
From mid April 2012, Council and Melbourne Water will be carrying out rectification works on the Edinburgh Gardens raingarden. The works are expected to take four to six weeks, provided there is not too much wet weather.
The aim of the works is to improve the speed at which water is absorbed into the underground storage tank.
Unfortunately, water is not draining fast enough into the tank and is instead pooling on the surface. As part of the rectification works, more feeder pipes will be installed below the garden’s surface to improve the drainage.
Other improvement works will include:
- raising the height of the steel edging on the western side of the raingarden to reduce overflows
- installing concrete strips at the back of the internal walls to slow the pace of overflowing water, reducing any damage caused to nearby garden beds.
For more information, please contact Mark Donnellan, Open Space Projects, on 9205 5724 or at Mark.Donnellan@yarracity.vic.gov.au
Soil testing
In November 2010, consultants from GHD (at the request of Council) performed detailed soil testing to determine the quality of the soil around the site proposed for the raingarden.
The area tested included the disused Ladies Bowling Club site and its nearby surrounds (an area within the southern section of the park between the tennis courts and the community room near the grandstand).
As expected, the test results identified contaminants such as mercury, lead, copper, chromium, arsenic and nickel and Poly–aromatic Hydrocarbons (a by–product of fuel burning) in underground sections of the park to a depth of about one metre.
Almost two–thirds (64%) of the tested soil was identified as clean fill, with the remaining 36% of soil sampled in the raingarden site found to contain some type of contaminants.
Contamination of this nature is typical across many former inner-city industrial sites, and is typical of many sites across Yarra, including Victoria Park where on–site contaminants were managed during redevelopment works in early 2011.
These materials had been expected due to the industrial history of Edinburgh Gardens, which last century variously housed a rail station and line, a tin can factory, a briquette store and a timber yard.
The results are also consistent with a site–wide environmental audit and site management plan conducted in 2000 which guides the ongoing management of soil at Edinburgh Gardens.
GHD subsequently conducted a site–specific assessment of the risks to human health based on the soil test results.
What does this mean?
The Human Health Risk Assessment concluded that the contaminated soil at Edinburgh Gardens posed a low public health risk to park users.
The low–risk rating was based on a scenario where a person visiting the site was exposed to the uncovered contaminated soil every day for two hours a day, for 30 years – a much higher visitation rate than would be likely to have occurred.
The Assessment indicated the risk of exposure was minimal providing existing cover from top soil and grass was maintained, as is provided for as part of Council’s regular park management.
Technical consultants also assessed the contaminants to have low or no leachability, meaning the possibility of leakage into other areas of clean soil or groundwater is highly unlikely.
Based on this advice, Council is satisfied that the risk posed by the soil is extremely low and can be managed according to National Environmental Protection Council requirements for contaminated land.
How will Council manage the soil?
The Human Health Risk Assessment confirmed the contaminated soil can be excavated and reburied at depth, so it can be capped with clean soil.
This work occurred in mid-2011 during the earthworks associated with the raingarden in accordance with a site specific Soil Management Plan.
An example of how known soil contamination has previously been accounted for during projects at Edinburgh Gardens can be seen in the construction of both playgrounds.
The new playground at the southern end of the park features a base comprising crushed rock, concrete, rubber and geotextile fabric under a layer of mulch around the play areas and equipment.
The playground at the northern end of Edinburgh Gardens features a base entirely covered by rubber.
View the concept plans and FAQs
More information about the project is available in this 
Fact Sheet (1,002.70kB).
Here is a PDF of the project newsletter distributed to residents in February 2011: Raingarden update - February 2011 (364.79kB)
Further Information
Justin Hanrahan
Manager - Open Space
9205 5720
Justin.Hanrahan@yarracity.vic.gov.au
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