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Garden Island Critical Infrastructure Recovery

Delivering high quality geotechnical, geophysical, and environmental investigation services for the design and construction of new wharves within an operational vital base for the Royal Australian Navy

The team were engaged by PSG Holdings to provide a geotechnical assessment of the area around and below the Oil Wharf, including a geophysical assessment of the subsea conditions. The geophysical assessment included 3D sonar scanning of the seabed (below the wharf deck), sub-seabed seismic profiling and bathymetry. This information was used to provide an understanding of the below seabed conditions and allow overwater boreholes to target specific risk areas.

Overwater boreholes were drilled from a floating barge, positioned off the Oil Wharf, to assess the seabed sediments for dredging purposes, as well as founding conditions for the new wharf. We used our in-house RTK GPS navigation system for high accuracy location during borehole set up, combined with our continuous bathymetric profiling to measure seabed depths, providing high quality overwater data.

Our team performed Vibrocore sediment sampling from a floating barge deck, recovering samples up to 3m below the seabed. Laboratory testing data was used to assess the feasibility in implementing sea disposal of the dredged material to be generated during construction works.

Our work was performed during normal base working periods, including regular vessel movements, without disruption or delay to naval operations.

Client name: PSG Holdings on behalf of the Department of Defence
Location: Sydney, NSW, Australia
Duration: 2014- 2017
Services provided: Tetra Tech Coffey delivered high quality geotechnical, geophysical and environmental investigation services for the design and construction of new wharves within an operational vital base for the Royal Australian Navy.

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