F10290 Hallam Valley Wetland Renewal - Aqua Metro Pty Ltd
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F10290 Hallam Valley Wetland Renewal

F10290 Hallam Valley Wetland Renewal


Melbourne Water


Hallam Valley Wetland, Hallam

Key Sector


Contract Type



10 months

Key Facts

  • Hallam Valley Wetland, one of Melbourne Water’s ten largest water systems, does not currently meet the regional performance objectives in terms of water quality or asset health.
  • To meet the requirements of the EPA and SEPP for targets on nitrogen, phosphorus and suspended solids the level of emergent aquatic vegetation must be increased, before which, civil works must be undertaken.
  • This is the first stage of a larger project to improve the health and efficiency of the Hallam wetland.


In order to reduce nitrogen, phosphorus and suspended soil entering Port Phillip Bay, Melbourne Water is obliged to meet standards set by the Victorian Environmental Protection Agency (EPA) and the State Environment Protection Policy (SEPP). Melbourne Water’s Stormwater Quality Treatment System (SWQTS) does not currently meet these standards due to insufficient Emergent Aquatic Vegetation (EAV) cover and so a preliminary works package was put together to complete the civil works on the site.

Scope of Service

  • Construction of new DN 600mm bypass pipe and headwall with penstock in the pit and floodgate at the outlet into the creek.
  • Construction of new DN750mm outlet and headwall with floodgate at the outlet. This new outlet will be the primary outlet and the existing DN1200 will serve as the overflow levels.
  • Building the new access track and hard stand areas for dredging the sediment ponds in the future.
  • Joining the 2 cells by removing the partition for the 2 different inlets to ensure equal flows in each cell.
  • Construction of 2 rock weirs in both cells to contain silt in the combined sediment pond and for uniform flow through each cell.
  • Construction of 3 control structures and associated pipework, headwall and penstock in each control structure to regulate the flow to the desired level from upper cells to the lower cell.
  • Removal of the existing control structure and construct a new rock weir with a nib wall for high level flows.


  • Inlet precast control pit weighs ranges from 17.5 t to 18.5t
  • 350t crane was used to place these pits
  • Filter trench around the outlet was approx. 8m deep and below the creek and wetland level
  • Sequencing of the works to ensure no to minimum bypassing required to carry out the works