GEA provided extensive input to this project from the initial desk study to observation of pile construction.

The desk study identified contaminative sources, historic bomb strikes and the likelihood of remnant foundations. The intrusive investigation included shallow boreholes, cable percussion boreholes to nearly 30 m and rotary boreholes to greater than 50 m including drilling through 1.2 m thick limestone layers in the Lambeth Group.

Following the ground investigation, GEA undertook a ground movement analysis to determine the impact of the construction of the 10-storey and 25-storey towers. The GMA was required to assess the likely movement of three large diameter Thames Water sewers and cascade structures present beneath the site. The initial foundation proposal was for single large diameter bored piles bearing in the Thanet Sand but a contractor’s alternative was proposed and GEA reviewed the impacts of a change to a piled raft with shallower CFA piles. We provided independent advice in respect of the two schemes, observed the test pile being installed and reviewed the test results.