Mining and underground construction specialist Cementation Skanska used a helicopter to lift 60 loads of chalk, each weighing 700 kilograms, to cap a hole on top of the 39 metre Neolithic age Silbury Hill in Wiltshire.
The stabilised hole allows Cementation to survey the hill’s interior using a revolutionary 3D technology developed in the USA called 3dT that sees through the ground. The technology processes raw seismic (sound) signals to produce computer images of inside the ground, showing density contrasts and identifying geological structures, cavities and man made excavations.
The signals are generated both at the surface and inside boreholes drilled into the ground, which is the next stage of the project.
Silbury Hill is the largest artificial prehistoric mound in Western Europe and the survey enables English Heritage to identify the extent of the weaknesses causing the hole and to develop a programme of repairs.
Cementation has exclusive rights to use 3dT in the EU and it is being rolled out across its worldwide operations.