Alphington Sewer

The Kew North Branch Sewer located in Melbourne is owned and operated by Melbourne Water. It has been upgraded to improve risk rating and capacity of the infrastructure.

Lend Lease Engineering Pty Ltd (LLE) was awarded the contract to undertake the works, which involved the construction of new manhole structures adjacent to the North and South banks of the Yarra River, as well as the below river siphon crossing between manholes.



The project required watertight cofferdams to retain soil and water to allow the safe construction of the permanent sewer works. Significant excavation depths were required – up to 11m in places – as well as an allowance for river flooding scenarios.

J Steel provided a certified design of temporary sheet pile retaining structures including all modular structural bracing where required. This included:

  • Geotechnical design
  • Structural design
  • Piling platform design including slope stability assessment
  • J Steel were able to design the temporary structures (sheetpiles and bracing) using their available stock materials significantly reducing lead times and construction programme.
  • Hot rolled high modulus AZ36-700N sheet piles were rented and reused multiple times on the project – a significant benefit when driving the sheets in the difficult geotechnical conditions. The Larssen interlocks with localised sealant mechanisms limited water inflow into the excavation.
  • HISTAR high strength beams were used for the heavy duty waler sections in the J Steel bracing system, significantly increasing spans between struts providing a clear working area, as well as reducing section sizes and the number of bracing levels.   The modular bracing system assembled with bolts on site contributed to the efficient delivery and erection.
  • The temporary steel structures were easily installed and removed after use satisfying the project’s environmental legacy requirements.
  • Quick review and approval of on-site modification through J Steel’s in house design engineers.

J Steel provided a professional and adaptive solution for these complex works, and were able to assist in the provision of all the required temporary works designs to allow us to successfully complete the major project works on behalf of Melbourne Water.

Paul Coysh
Construction Manager Alphington Sewer Project Lend Lease