The ground investigation tested soil conditions for the design and construction of an onshore electrical sub-station as well as the installation of underground cables between the landfall site at Sizewell and the sub-station.
Soil samples were also collected to provide information on the construction and design of a new access road needed to support heavy plant traffic.
Additionally, the project involves investigating the strata beneath the shoreline to establish the optimum route of the off-shore/on-shore connection. This will help assess the feasibility of cable installation using horizontal directional drilling.
The contractor's principal engineer Martin Caudell said work involved a mix of seismic surveys, in situ cone-penetration tests, exploratory bore holes and trial pits.
Site geology is the Quaternary Crag Group that is predominantly sands with overlaying localised glacial deposits. Along the beach area are marine sand and gravels that Soil Mechanics said will need drilling fluids for the directional drilling part of the scheme to remove the cuttings and keep the boreholes open.
The planned wind farm will produce 500MW of electricity via 140 wind turbines sited around the Inner Gabbard and the Galloper sandbanks.
GGOWL claims it will be the first UK offshore wind farm to be built outside territorial waters and will provide electricity for more than 415,000 homes, equivalent to the domestic demand of Suffolk.
Soil Mechanics is waiting for access to be agreed to commence a second phase of the field work at the site.