Site investigation contractor Andrews Survey has carried out two investigations for wind farm sites off the east coast of England.
The first involved rapid acquisition of data to establish the seabed features of the turbine site and the route of the linking power cable.
Andrews carried out a sub-bottom profile and sidescan sonar survey, supplemented by a nearsurface geotechnical site investigation to the beach landfall.
The survey was then extended to the electricity substation using land techniques.
Andrews' development of lightweight CPTs for marine cable site investigations allowed work to be carried out from a small boat, allowing faster measurements and greater coverage in shallow water than conventional jack-up platforms.
Offshore, the company used its Mini-cone CPT with a 25kN/cm 2cone capable of 5m penetration.
The route of the cable from the beach landfall to the substation was surveyed using a 200kN land CPT truck.
The second site required deeper penetration for a meteorological mast foundation and a wider investigation across the entire turbine site using near-surface geophysics.
A heavy duty hydraulic vibrocorer on a 68m vessel was used to produce 6m cores into the weathered chalk, which were analysed at Andrews' Yarmouth soils laboratory.