SITE INVESTIGATIONS for a liquid natural gas terminal on the Isle of Grain in Kent had to contend with an environmentally sensitive location and finish before the winter migration of local birdlife.
Working for Skanska Whessoe, Fugro Engineering Services (FES) carried out land and marine investigations at Horsehoe Point to establish depth to the underlying London Clay and the thickness of alluvium in the estuary over a 200m by 400m area, to confirm pile design.
FES used a self-propelled jack-up to carry out CPTs up to 32m deep and sink boreholes to depths of 45m. It also put down two, 40m boreholes and four piezocone CPTs to 35m depth on land. Work revealed London Clay lying at between 19m and 27m, overlain by soft river clays, loose silts and sands.
The terminal site, which includes an unloading jetty and pipeline, runs alongside the former BP Grain Terminal close to a Site of Special Scientific Interest. As well as avoiding interference with migrating birds, there were tight controls on the discharge of any borehole arisings into the estuary.