Located in Wonthaggi on a 263 hectare site, the Victoria Desalination Project comprises 29 structures including the reverse osmosis building, the heart of the VDP. The plant has a guaranteed production capacity of 150 billion litres of water a year and the ability to deliver 400 megalitres per day.

Geotech’s role

Geotech was engaged to design, construct and then operate a specialist grout spread of equipment to grout the seaward inlet and outlet structures associated with the Victorian Desalination Project. Grouting works occurred from an offshore vessel operating adjacent to the jack-up barge located 1km offshore in Bass Strait.

Geotech’s technical staff prepared and tested the required range of trial grout mixes until the desired grout mix was achieved. Key parameters were stability, consistency, strength and bleed. These trials were undertaken in our NATA registered laboratory. Concurrent with the mix trials, Geotech’s workshop designed, manufactured and commissioned the grout batch plant.

During the construction planning phases the VDP tunnel crews sought ideas for early warning indications that the outer structures had been reached while tunnelling towards them. Geotech suggested the possibility of colouring the grout encasement of the structure as a flagging mechanism. Following trials to ensure that the colouring did not compromise any of the key mix parameters, this innovative colouring procedure was adopted. As the tunnelling approached the structure, the cuttings were clearly identified as different, indicating the process was within several hundred millimetres of the structure. 

As a side note, Geotech also completed a significant batter stabilisation contract at the actual VDP site at Wonthaggi. This involved the drilling and installation of thousands of soil nails and drainage holes, along with the shotcreting of batters. 

Disciplines covered 

• Grouting
• Marine works
• NATA laboratory
• Soil Nails
• Shotcrete