Rain garden - Wanniassa (Lake Tuggeranong catchment)

Rain garden site at Athllon Drive, Wanniassa

14/12/2018 - Civil works continue. Recent storm events had little or no impact.

8/8/2018 – Construction continues with the laying of the foundation for the gross pollutant trap (GPT)


Rain garden, Athllon Drive between Langdon Avenue and Fincham Crescent, Wanniassa

Please note: Fences have gone up around the construction site which means the informal parking beside the playing fields is now closed.

A new rain garden beside Wanniassa Playing Fields will improve the quality of water flowing into Lake Tuggeranong in two ways:

  1. The rain garden will filter and clean urban stormwater run-off, removing nutrients and pollutants that contribute to blue-green algal blooms.
  2. It will replace an informal parking area which is causing erosion, with sediment flowing into the creek and Lake Tuggeranong when it rains.

It will also be a valuable educational resource for students at the adjacent St Anthony's Primary School, with rocks and seating in two areas designed to serve as outdoor classroom spaces.

The finished rain garden (comprising three separate pods) will have a combined treatment area of approximately 2,315 square metres and remove over 20,000kg of nitrogen, phosphorous and suspended sediment every year.

One tree will need to be removed but several new trees will be planted. Casuarina Cunninghamiana will match the existing trees and provide additional shade for the rain garden.

During construction, parts of the nearby cycling and pedestrian paths will need to be closed for short periods of time. Diversions will be put in place but cyclists and walkers may have to cross access roads or wait for site traffic to pass. Everyone is urged to take care while in the area.

Catchment Lake Tuggeranong
Start date May 2018
Construction finishedOctober 2018
Anticipated establishment periodTwo years from open date*
Open for public useJune 2019

+Construction may be delayed by a number of factors, including bad weather.
^The establishment period may change depending on ground and weather conditions. During the establishment period, flows into and through the asset will be managed to suit the conditions and to protect and nurture the plants.
*Some areas of the site may remain closed to allow for plants to establish.

Design changes

Although water quality is the priority for ACT Healthy Waterways, the project team is also working to a fixed budget and timeframe.

During the final design phase, some changes were made to the original concept designs to accommodate services, community feedback and maximise water quality benefits.

  • The final design includes three rain garden pods instead of two which will enable better distribution of the stormwater across the surface of the raingarden, resulting in healthier vegetation, fewer maintenance issues and better performance.
  • The treatment area is 6.5% larger than in the design presented for community consultation, with a consequent increased treatment capacity.
  • To reduce the potential for clogging of the filter media, the final design incorporates both a GPT and a sediment forebay. Together, these will remove approximately 90% of suspended matter from the stormwater, better enabling the raingarden to remove dissolved contaminants such as nutrients.
  • To reduce the 'wear and tear' on the grassed areas, the access tracks for maintenance vehicles have been extended in the final design.
  • Underground telecommunication cables will be re-routed to eliminate conflict with the western-most raingarden pod.

More information

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How this project might impact you

  • Trucks will pass in and out of the area during the improvement work. Routes have been established to minimise traffic disruption and noise.
  • Detours for walkers and cyclists will be in place and will be clearly signposted.
  • The construction site will be fenced for public safety during the entire length of the project.
  • The contractor has prepared a Construction Environment Management Plan (CEMP) to detail how it will deal with flora and fauna issues.

Landscape design plan

Click on the image to enlarge.

Landscape plan for rain garden at Athllon Drive between Langdon Avenue and Fincham Crescent, Wanniassa