Donnybrook Road Branch Sewer

The Donnybrook Road East Branch Sewer project is an integral part of Yarra Valley Water’s infrastructure servicing the Northern Growth Corridor. The project connects development along Donnybrook Rd to the Amaroo Main Sewer.

Califam’s scope included installation of approximately 2km of GRP gravity sewer between 600mm and 750mm diameter, at depths varying between 9m and 14m which was installed using primarily trenchless methodology.

The main challenges faced included:

• Depth of works
• Access restrictions with private landowners
• Working close to Donnybrook Road and an existing water main parallel to the alignment.
• Mixed ground conditions varying from clay to extreme hard basalt.
• Complexity of maintenance holes due to depth and design.

Some of the key achievements on the project included:

• The selection of trenchless methodology to reduce the impact on stakeholders
• Utilisation of various shoring techniques for excavation of shafts 12-16m deep including shields, rock anchors and mesh to protect workers from excavation collapse in varying ground conditions and while protecting existing assets in the vicinity.
• The use of pre-cast HOBAS GRP maintenance holes delivering quality, safety and timing advantages to the project.