Northern Sewerage Project, Stages 1 & 2
Stage 2 will provide both a gravity extension upstream of Stage 1 and an outlet for the sewers servicing the Merri Creek and Edgars Creek catchments. The proposed 4.7-kilometer-long Stage 2 tunnel will feature an internal diameter of 2.4 meters and an average depth of 34 meters. Tunnel construction will radiate from a single major shaft, measuring approximately 11 meters in internal diameter. Additional shafts (for TBM removal, permanent access structures, and connections to existing sewers) will range in depth from about 20 to 60 meters. The majority of tunneling likely will cut through basalt, necessitating the use of a hard rock tunnel boring machine.
Jacobs Associates, working with Sinclair Knight Merz (SKM), led the tunnel and shaft design on both stages of the project. Jacobs Associates now offers construction services to the NSP’s owners, Melbourne Water and Yarra Valley Water. The owners chose a unique procurement method for this project: a form of design-build that shares risks and rewards among “Alliance” members based on their ability to control the work. Members of the NSP design and construction team include the owners, Connell Wagner, the John Holland Group, SKM, and Jacobs Associates.
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