Belconnen Subsurface Wetland
Did you consult with the community on the proposed wetland?
We held information sessions at the Belconnen Library on Tuesday, 11 and Saturday, 15 October 2022.
We heard a range of feedback from the community, including:
- requests for a whole-of-site design to improve community amenity, such as installing lighting, BBQ facilities and seating, upgrades to the playground, weed removal and rubbish bins;
- that the site be designed to improve biodiversity and habitat for native species, including through introducing open water in the wetland;
- that there remains enough space for people to play sports; and
- new paths around the wetland should connect to existing pathways and the underpass.
How will you use the community feedback?
We are altering the wetland design in response to community feedback and will consult with the community on any new design options.
Will the new design continue to be for a subsurface wetland?
We will consider a range of options, including subsurface wetlands and raingardens with open water based on community feedback and funding availability.
When will the Development Application be submitted and how can I make a representation?
The revised Development Application is expected to be publicly available in late 2022 or early 2023 once the feedback from the community consultation is considered and design changes made. There is the potential that further public consultations may occur before the DA is lodged.
You will be able to make a representation during the public notification period, which will be open for 15 working days. Any representations will be considered as part of the Development Application decision process. If the wetland receives all the required approvals then construction will start around mid-2023 and be completed by the end of 2023, weather permitting.
Why was the Belconnen Oval location chosen?
The Belconnen Oval location was chosen because:
- Lake Ginninderra missed out on water quality infrastructure in Stage 1 of Healthy Waterways.
- While Lake Ginninderra has the best water quality of Canberra’s three urban lakes, there are occasional outbreaks of algal blooms. The incidence of algal blooms can be expected to increase with urban infil in Belconnen unless the government takes steps to mitigate water pollution through building regulations, public education and the construction of wetlands like the one proposed for Belconnen Oval.
- Belconnen Oval was identified through a feasibility study and further supported by earlier community stakeholder requests for a wetland to be built at this site.
- Belconnen Oval is an open space near the bottom of the studied catchment and provides access to the stormwater pipes running beneath the oval that carry the confluence of water from the catchment. Importantly there is sufficient space to bring the water within the pipes to ground level via a gravity system.
Why was a subsurface wetland chosen in the original proposal instead of other water quality asset types?
The portion of nutrient pollution in Canberra’s stormwater that is dissolved is quite high; approximately 50 per cent. The design of this wetland is thought to be particularly effective at intercepting dissolved nutrients compared with other wetland/pond designs.
It is an innovative design that has not been used in the ACT before.
Will a subsurface wetland increase flooding risk in the area?
No. All of the water to and from the wetland is piped underground, and also travels underground within the wetland. The oval is a flood retention basin, so the entire area could be subject to flooding in a very large storm.
How will the wetland improve water quality?
The wetland will include a gross pollutant trap that will trap sands and some silts. Clays may get trapped in the gravels at the base of the wetland. Excess nutrients will be absorbed by the wetland plants, and nitrates will be released to the atmosphere as nitrogen gas through natural processes within the wetlands.
How will the project be monitored and maintained?
The inlet and outlet will be monitored for flows and pollution so the government can understand and track how well the wetland is performing in improving water quality.
The government will regularly undertake operations and maintenance activities.
Landcare groups have been established to help care for constructed wetlands, raingardens and ponds elsewhere in the ACT. The government would welcome the community to establish another one for this wetland.
Will the wetland increase the ecological value of the area?
Absolutely. Compared to a grass playing field, the habitat provided by the bays of sedges and rushes is of far greater value. The addition of a pond, at the urging of the local community, will further enhance the habitat value of the wetland.
Will any existing trees be removed or new trees planted?
The original design suggests seven trees will be removed, mainly to enable a trench to be dug between an existing stormwater pipe and the inlet to the wetland.
Balancing that, more than 50 trees will be planted around the wetland, creating an attractive, leafy wetland.
These numbers may vary with any new design options.
Will the project increase the number of mosquitos in the area?
This is not expected. Where the water travels underground it does not harbour mosquitos. A pond is being considered in the redesign in response to community feedback, but would have healthy plants that harbour beneficial insects that predate on mosquito larvae.
Will the project cause bad smells in the area?
No bad smells have been detected from the ACT’s existing raingardens and none are expected to afflict this wetland.
What size will the subsurface wetland be?
The current wetland design would take up around 40 per cent of the playing field, on the eastern side.
Fadden Mini Raingardens
Did you consult with the community on the proposed raingardens?
We held information sessions at the Tuggeranong Library on Wednesday, 12 and Sunday, 16 October 2022. Feedback from the community, included:
- a preference for fewer new trees than planned to retain open space for children to play; and
- that new trees should not shade gardens where possible.
How will you use the community feedback?
We will incorporate the feedback into the raingarden designs.
When will the Development Application be submitted and how can I make a representation?
The Development Application (DA) will be submitted on 28 October 2022. Once the DA is processed, you will be able to make a representation during the public notification period, which will be open for 15 working days. Any representations will be considered as part of the Development Application decision process. If the raingardens received all the required approvals then construction will start in February or March 2023 and be completed by mid to late winter, weather permitting.
How was the location of the raingardens chosen?
The Fadden catchment was one of three examined within the Lake Tuggeranong catchment, which is known to experience poor water quality.
The Fadden community has been vocal in asking the government to clean up waterways.
Designers were asked to look for opportunities to prevent stormwater drains getting polluted. A number of potential locations and assets were examined within the Fadden catchment.
These four mini raingardens stood out for their high performance and the feasibility of building them.
Will the mini raingarden increase flooding risk in the area?
No. Flood modelling has been performed and the raingardens will not increase the risk of flooding.
Will the project increase the number of mosquitos in the area?
No. There will be no still, open water in a raingarden where mosquitos can breed.
What will the raingardens look like?
They will look like small, rectangular garden beds planted with sedges and rushes.
Why were raingardens chosen instead of other water quality asset types?
Raingardens are one of the most effective designs per unit area for filtering pollution, so they are useful for fitting into small spaces in green corridors within suburbs.
Why are the raingardens “mini”?
To differentiate them from the big raingardens we built in the catchment like the one next to Jondol Place in Isabella Plains.
Will any existing trees be removed or new trees planted?
Two trees may need be removed and a number will be planted surrounding the raingarden at the base of Ogden Close.
Residents have asked us not to plant trees in the existing open space further up the green corridor so that children can have an open area to play in.
Will the raingardens increase the ecological value of the area?
In a small way, yes. They will provide good habitat for frogs to shelter in and feed, and will provide food for passing birds.