Rain garden - Karabar (Upper Molonglo)

15/2/2019 - Gravel in place with concrete walls about to be constructed.

14/12/2018 - General earthworks have commenced.

8/11/2018 - Letters advising of the start of construction are being delivered to residents who live within a 100m radius of the site. Please check your letterbox. You can also view the letter here.


Rain garden between Alanbar Street and Kenneth Place, Karabar

A new rain garden will be constructed in an urbanised area in Karabar.

With a total treatable area of 950 square metres, it will filter and clean water diverted from nearby pipes before returning it to the stormwater system.

Approximately 27,500 kilograms of suspended sediment, nitrogen and phosphorous will be removed every year from stormwater bound for the Queanbeyan River.

The rain garden is the 17th of 20 ACT Healthy Waterways infrastructure projects and the only one located outside the ACT.

It is bounded on all sides by homes and streets and constrained by overhead powerlines, existing stormwater pipes and underground services.

It is also positioned within an existing overland flow path which diverts and moves water during major storm events. For this reason, the design ensures that flood capacity of the space is not reduced.

ACT Healthy Waterways identified this site as a priority early in the project as it is upstream of the Molonglo River, Jerrabomberra Wetlands and Lake Burley Griffin.

An existing cycle path will be relocated to the east.

Start date

November 2018

Likely construction finish date

May 2019+

Anticipated establishment period

Two years from the finish of construction^

Open for public use

May 2019*

+Construction may be delayed by a number of factors, including bad weather. Planting is part of the construction phase and the timing of the growing season may impact on construction timelines.
^Water plants in particular may take up to two years to establish. The length of time may vary 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 the public past this point to allow for additional planting or for plants to become established.

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.

  • Kenneth Place rain garden removed due to insufficient area and clashes with underground services. Replaced with stormceptor underground treatment unit.
  • Shape of southern rain garden adjusted to suit detailed survey.
  • Above ground sediment bays deleted due to proximity to public, additional capacity built into underground pollutant trap instead.
  • Adjustments made to driveways and service vehicle access arrangements to improve safety.
  • Diversion pipe removed from Lily Place/Kenneth Place alleyway due to change to underground treatment in Kenneth Place.

More information

Find out what you can do on your own block to improve water quality in our lakes and waterways.

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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.