Alphington Sewer 560x2

Alphington Sewer

Principal: Melbourne Water

Contractor : Lend Lease Engineering Pty Ltd

Engineer: J Steel Australasia Pty Ltd

Date: Jul 2014 - Jul 2015

Scope/Product: Design and material hire           



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.

Key Requirements and Scope:

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 allowance for river flooding scenarios.

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

  • Geotechnical design
  • Structural design
  • Piling platform design including slope stability assessment

"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)

Solutions and Benefits:

  • 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's structural engineer supervising the construction  

                                                                                                                                                                              11m excavation for manhole

                                                                                                                                                                             Inside the river crossing cofferdam





Ask A Question

By clicking Submit you are agreeing to our Terms & Conditions and Privacy Policy | * Denotes a mandatory field.