Melbourne Water is upgrading four retarding basins in the Roxburgh Park area to ensure they continue to function effectively. The upgrade works will ensure the retarding basins continue to reduce the risk of flooding to the community.

Why we are doing these works

Retarding basins play an important role in managing stormwater. Without them, people, properties and businesses would be at significant risk of flooding. They are low lying areas of land set aside to temporarily store stormwater during very high rainfall. When heavy rain occurs, the embankments of retarding basins hold back stormwater and slowly release it downstream, reducing the risk of flooding to communities.

More information on how retarding basins work can be found on the retarding basins webpage

Melbourne Water has over 200 retarding basins that we regularly assess for risks, conduct maintenance on, and upgrade as necessary. The Australian National Committee on Large Dams (ANCOLD) guidelines represent the best Australian and international engineering practices in the safe design, management and operation of dams. We use these guidelines to manage our retarding basins.

Retarding basins in the Roxburgh Park area have recently been assessed against the ANCOLD guidelines. The assessment showed that upgrade works were necessary on four retarding basins to meet new standards and to ensure that they continue to operate safely and effectively.

What’s happening and when

Melbourne Water is upgrading the retarding basins at St Clair Reserve, The Shankland Reserve, Lake Mcivor Reserve, and Tiffany Crescent Reserve. These works started in October 2017 and are expected to be complete by June 2018 (weather permitting).

Aqua Metro Services (AMS) is undertaking these upgrade works on behalf of Melbourne Water.

St Clair Reservoir

Works at this retarding basin in St Clair Reserve (known as Shankland Gully 2A) include:

  • removal of trees from the embankment 
  • earthworks to reconstruct and smooth out upstream and downstream embankments 
  • earthworks to remove silt (fine sediments) in the retarding basin
  • installing an outlet filter 
  • constructing a safe access track to the penstock (structure that controls and directs the flow of water) 
  • installation of rockwork to encourage dog access to the water and to allow unrestricted views, fishing and other recreational activities at one designated location 
  • reinstating the area with topsoil and grass upon completion of works. Temporary fencing around the retarding basin will remain in place until the grass has established

These works are anticipated to be complete in April 2018.

Following completion of these upgrade works, native wetland vegetation will be planted within the retarding basin (not the embankment) to help treat stormwater and improve water quality downstream. The vegetation will also provide habitat for birds, fish and frogs. 

Initial edge planting will take place in June 2018, with planting of wetland vegetation in the middle of the retarding basin in summer 2018-19.  

 

Map of proposed works at St Clairs reservoir

Shankland Reserve

Works at this retarding basin (known as Shankland Gully 2C) include:

  • earthworks to excavate and re-compact soil material on the downstream embankment wall
  • removal of trees and other vegetation from the embankment 
  • localised repairs to the outlet channel
  • reinstating the area with topsoil and grass upon completion of works

Works are anticipated to be complete by June 2018.

Map of proposed works at Shankland Reserve

Lake Mcivor

Works at the Lake Mcivor retarding basin are now complete. This included:

  • minor earthworks to remove poor outlet material and replacing this with re-compacted soil 
  • installing a sand filter 
  • reinstating the area with topsoil and grass upon completion of works

Map of proposed works Lake Mcivor

Tiffany Crescent

Works at the Tiffany Crescent retarding basin are now complete. This included:

  • minor earthworks to remove poor outlet material and replacing this with re-compacted soil 
  • installing a sand filter 
  • reinstating the area with topsoil and grass upon completion of works

Map of proposed works at Tiffany Crescent

What to expect during construction

We will do everything possible to minimise inconveniences and disruption during construction, however local residents and visitors may notice:

  • large trucks and other construction vehicle movements in the area, with potential traffic disruptions - traffic management plans will be in place to ensure public safety 
  • reduced access to shared paths, with temporary diversions in place for cyclists and pedestrians around construction areas  
  • some noise, dust and vibration from construction works
  • changes to reservoir water levels

Construction hours will be 7am – 6pm Monday to Friday, and 7am – 1pm Saturdays. 

We will maintain contact with directly affected residents, businesses and stakeholders during the upgrade works to keep them informed about potential impacts and timing. We will provide further information as the works progress via online updates and community bulletins.

Melbourne Water thanks the community for their patience while we undertake these essential works.

Tree removal

To ensure the retarding basins continue to operate safely and comply with the ANCOLD guidelines, trees and other vegetation on the embankments need to be removed as part of the works. Trees can cause embankments to fail, particularly in high rainfall events. They do this by increasing the risk of:

  • tree roots weakening the embankment
  • internal erosion and displacement of soil - tree roots create erosion pathways through the embankment which are intensified when a tree dies and its decaying roots leave holes through the embankment
  • trees falling over and uprooting during storm events, taking part of the embankment with them, resulting in a hole in the embankment 
  • water speeding up and pooling around tree trunks, causing erosion 

We understand the importance of trees to the local community and we are working closely with Hume City Council to replant trees and other vegetation elsewhere.

Contact us

If you have any questions or feedback, or if you would like further information about the upgrade works, please contact:

Last updated:
12 April 2018