Two of the most common types of pre-construction survey activities are geophysical and geotechnical surveys. Both surveys require a permit and approval from related agencies. While conducting offshore survey operations, we take the following protective measures:
Vessel speeds
To reduce the risk of interaction with marine mammals and protected species, our survey vessels operate under a 6-knot speed restriction during transit and operations.
Types of offshore survey work
Offshore geophysical surveys
We conduct high-resolution geophysical (HRG) surveys to map the seafloor and the geology beneath it, and to identify archaeological resources and debris left by other ocean users.
Equipment used during these surveys includes both acoustic equipment using varying frequencies of sound and passive sensors that do not emit sound. The sensors are either hull-mounted or towed above the seafloor behind the vessel. During HRG survey operations, vessels typically move at a low speed, between 2-4 knots (3-5 mph) transiting along straight survey lines.
Offshore Geotechnical Site Investigations
Geotechnical Site Investigations (GTSIs) collect data from below the seafloor to assess the mechanical behavior of soil and rock. We take measurements of soil properties, along with physical soil and rock samples, which we send for laboratory testing onshore. GTSIs do not produce any significant acoustic noise and therefore don’t pose a risk to marine mammals .While undertaking GTSIs, the vessel remains stationary on-site.