What is it all about?
Hurstville City Council is constructing a bioretention system and landscaping works to upgrade Webbs Dam. Council is undertaking these works with funding support from the NSW Environmental Trust under the Lower Georges River Sustainability Initiative, the NSW Government's Waste and Sustainability Incentive Payment Program, and the Sydney Metropolitan Catchment Management Authority’s Botany Bay Water Quality Improvement Program.
During 2011, Council worked closely with the local community and the Lugarno Progress Association to develop a Landscape Masterplan that will guide the staged upgrade of the dam.
These works represent Stage 1 of the plan.
What is going to happen?
In order for the works to take place, the dam will be drained in accordance with a dewatering plan that has been prepared by Council’s consultant team. As part of this process, some of the native animals living in the dam (e.g. turtles and eels) will be relocated elsewhere.
Once this has been completed a bioretention system will be constructed in the eastern section of the dam. This will filter and treat stormwater flows into the dam, which in time will be used to irrigate the adjoining sports fields. In the meantime, the improved water quality will help reduce the incidence of algal blooms within the dam and maintain the quality of remnant bushland downstream of the site.
Landscaping works along the southern edge of the dam will also improve public safety within the vicinity of the picnic area and barbeques.
What will it look like?
A plan of the Stage 1 works is shown on the back of this flyer. Key elements include the reshaping of the southern edge of the dam, the construction of the bioretention system, sandstone inlet and overflow structures, and the planting of more than 8000 native plants.
How will the bioretention system work?
Water will flow into the system via the existing stormwater pipes and sandstone forebays, trapping sediment and gross pollutants such as plastic bottles and aluminium cans. The water will then drain through the bioretention system, which includes layers of sand and other media to remove finer sediment and nutrients like nitrogen and phosphorus. The nutrients will then be used by the plants and small trees throughout the system.
Water will not pool more than approximately 20cm within the basin and will drain away rapidly. During larger storm events, water will overflow from the basin into the adjoining dam.
When will work commence?
Work is now underway and is expected to be completed in September 2012, weather permitting.
Like to know more?
Down load the information on this web page  Project flyer (1.98MB)
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Download a copy of the project flyer
View a presentation made to the Lugarno Progress Association that includes more information about the project
Find out more about the Lower Georges River Sustainability Initiative (LGRSI)
Find out more about the Botany Bay Water Quality Improvement Program
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