The full potential of geophysics in engineering investigations is yet to be realised. With investigative capabilities ranging from the detail of well-logging to the long traverses of studies of geological structure, the many available techniques can provide important information about the ground, its mass properties, its small-scale variations, and its anomalies of structure or content. The advantage of a geophysical survey is that it enables information to be obtained for large volumes of ground that cannot be investigated by direct methods because of the costs involved. The applications of geophysics in the characterisation of contaminated land, eg the distribution and migration of pollutants in the ground and groundwater, are still developing, but with great potential. These are still insufficiently or inappropriately used in engineering and the newer capabilities are not appreciated. There is a need for up-to-date guidance about how to apply geophysical investigations. The underlying aims of this report, therefore, are to prepare guidance for civil and geotechnical engineers, and their clients on: the integration of geophysical investigations into the design and construction process the use of geophysics for determining engineering parameters the capabilities of geophysics for investigating ground contamination and grouion. 1.1 ABOUT THIS REPORT This report was prepared jointly by CIRIA and a working party of the Engineering Group of the Geological Society. In the mid-1990s, the Engineering Group of the Geological Society re-convened the working party to update its report, Engineering geophysics, which was published in the Quarterly Journal of Engineering Geology in