Multi Disciplinary Marine Survey of a Bay in Sydney Harbour

A Sydney wharf required an upgrade and GBG was hired to provide geotechnical information and to detect any foreign objects on the seabed.

Due to the high expense of undertaking overwater drilling and the requirement for continued access to the wharf structure for vessel refuelling it was decided that geotechnical information on the seabed depth and the sub bottom geology could best be provided using shallow marine geophysics.

The project requirements were to map geological units with emphasis on the mapping of bedrock to assist in the design and placement of piles for an upgrade to the current wharf facility. GBG Australia carried out marine seismic reflection, marine seismic refraction as well as single beam bathymetry for an area of 150m either side of the wharf and 100m in front of the wharf based on the proposed wharf expansions. Marine gradiometer and sidescan sonar were also collected to locate/image any objects on the seabed.

Marine seismic reflection data were processed and presented as 3D contours and marine seismic refraction data was processed to obtain indicative material strengths required for pile design.

GBG Australia were employed as Geophysical Consultants for the project. The project was undertaken by Simon Williams acting as project manager and lead geophysicist and David Mitchell as deckhand and onsite electrical and acoustic engineer.

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