Marine Geotechnical Investigations
To inform the next stage of detailed design planning for Westport, we are collecting data about the sub-sea conditions in the areas where development is proposed. This includes the footprint of the port terminal in Cockburn Sound and shipping channel to the north.
Marine geotechnical investigations involve drilling below the seabed to collect soil and rock samples. This allows us to assess the underground composition and condition of the area, ensuring safe, efficient, and reliable design for future construction.
The investigations are being carried out from two jack-up barges, scheduled to operate across the area from mid-2025 through to late 2026.
As part of the marine geotechnical investigations, a marine vessel will be in the area for two weeks in late July to early August to carry out cone penetration testing. This involves pushing a probe into the seabed to measure soil resistance. The vessel will operate 24 hours a day during this period to complete the work efficiently.
Early Investigations Using Sound Waves
Before scoping geotechnical investigations, we carried out geophysical surveys in the same area using sound waves to map the subsea area.
These earlier surveys gave us a broad picture of what’s beneath the seabed, including identifying the topography and magnetic and density properties of rock layers. However, to progress the engineering and final designs, we now need the physical samples and detailed data.
Frequently asked questions
What are marine geotechnical investigations?
Marine geotechnical investigations are an investigation of the ground beneath a project site. It helps engineers understand the soil and rock conditions so that infrastructure can be designed to be safe, stable, and long-lasting.
How do you collect the soil and rock samples?
The investigations involve drilling boreholes and bringing up core samples, which are then tested in a laboratory. This process helps us understand the strength, type, and stability of the ground beneath the surface.
Where will the surveys take place?
The investigations will be conducted throughout the proposed port terminal footprint area and navigation channel (see map). A tugboat will move the jack-up barges progressively through the area to ensure sufficient ground samples are collected across the site.
What is a jack-up barge, and why is it used?
A jack-up barge is a type of floating platform equipped with legs that lower to the seabed and raise the platform above the water’s surface. This creates a stable base for drilling and other investigation work. See image below.
Is this work safe for marine life or the environment?
Yes. All activities avoid seagrass meadows and follow strict environmental management plans to avoid harm to the marine ecosystem.
Will there be noise, vibration, or pollution?
There may be some noise and minor vibration from drilling equipment, but it is limited and temporary. All operations follow environmental guidelines to control impacts, including spill prevention.
Are there risks to divers, boaters, or fishers?
There is a 50m buffer zone established around the jack-up barge to keep everyone safe. We also communicate with local marine users and authorities to coordinate activities.
Will the results be shared with the public?
Where appropriate, we’ll share summary findings through project updates, newsletters and stakeholder briefings – especially if they influence design or timing.
For more information
Please contact us on 1800 875 000 or at enquiries@westport.wa.gov.au.
Example of jack-up barge undertaking marine geotechnical surveys.
Marine vessel undertaking cone penetration testing for two weeks in late July 2025.