A ground investigation was undertaken for Renewable Energy Systems (RES) in connection with a proposed wind farm in Cambridgeshire. The development comprised the construction of thirteen wind turbines, access routes, a sub-station and a meteorological mast.
With the benefit of a desk study the geology was expected to be dominated by ‘chalk’ with the possibility that natural or man-made cavities could be present.
The ground investigation therefore took place in two stages. Initially a programme of ‘deep’ trial pits was undertaken at the turbine locations, alternative turbine locations and at the proposed meteorological mast, sub-station and construction compound sites. This enabled a second stage of investigation which comprised light-cable percussion boreholes and static cone testing, to target potentially anomalous areas. The investigation was also designed to provide information for the foundation design of the turbines and the other structures.
In addition, dynamic cone penetration (DCP) tests for the access route foundation design and BRE365 soakage tests to determine soil infiltration rates for soakaway drainage were undertaken at several exploratory locations.
RSA Geotechnics provided information on the engineering condition of the chalk. This involved consideration of the effects of cyclic loading due to the rotating blades, on the founding material and determination of the small strain shear modulus from seismic cone testing.