This project in West Belconnen is one of the biggest of the ACT Healthy Waterways sites. It includes two wetlands, a sediment pond, a vegetated swale and the rehabilitation of a degraded anabranch on two sites about 400m apart. Construction will be completed by the end of June 2019.
The wetlands on the southern site are being “retrofitted” into an established urban catchment, drawing water from the existing stormwater system. They will have a combined surface area of approximately 5,100 square metres.
The southern site also includes a gross pollutant trap, sediment pond and associated drying area, designed to dewater sediment before it is collected and taken off site. Rock armaments will protect the wetlands from periodic flooding.
The wetlands were carefully positioned to avoid experimental grassland plantings maintained and studied by the local catchment group.
Similarly, changes to the original plans for the northern site were prompted by community concerns over the potential loss of a patch of crab apples.
The final plans include the extension of an existing swale (a depression that collects and carries stormwater) from 85 metres to 135 metres. It meanders through surrounding grassland, filtering water discharged from the pipe network before it flows into Ginninderra Creek.
The existing anabranch (a disconnected part of the creek) was congested with trees, undergrowth and sediment deposits which mean water only enters it during floods. As a result the anabranch was cleared and regraded to restore natural flows.
Together, the various water quality treatment components will remove over almost 36,000 kilograms each year of nitrogen, phosphorous and suspended sediment from urban stormwater before it enters Ginninderra Creek.
The project is one of three water quality infrastructure projects built downstream of Lake Ginninderra. Another wetland on the corner of Ginninderra Drive and Copland Place and the revegetation of a stormwater drain in Florey complete the set.
Design changes
During the final design phase, some changes were made to the original concept designs to accommodate services, community feedback and maximise water quality benefits.
- Armaments were added to protect the wetlands from localised flooding.
- A drying area was added to dewater sediment removed from the GPT and sediment basin.
- The small wetlands planned for the northern end of the site were replaced by a wide vegetated swale.
More information
Find out what you can do on your own block to improve water quality in our lakes and waterways.
Landscape design plan
Click on the image to enlarge.
