Geophysical survey planning for the Dounreay and Sellafield geological investigations

Between 1989 and 1994 two large engineering site investigation projects in the United Kingdom at Dounreay in Caithness and the Sellafield area in West Cumbria were carried out for the study of possible locations for a deep underground facility for low-level and intermediate-level radioactive waste. In the geophysical domain, management of a diverse range of specialist services required initial desk studies, survey design, acquisition and processing supervision, interpretation, reporting and archiving. Document creation (design intent memoranda, tenders and contracts, Quality Assurance, technical reviews and reports) together with technical control during the data acquisition phase was followed by involvement in the interpretation of the results. A range of geophysical methods were employed including onshore and offshore seismic reflection with associated gravity acquisition, transition zone seismic, airborne geophysics (utilizing spectroscopy, magnetics and VLF) and ground electromagnetic surveys. At the peak of activity, responsibility for the geophysical operations involved the simultaneous management of five held crews - two land seismic with some gravity, one marine seismic with gravity and two helicopters acquiring airborne data - as well as ongoing VSP in the deep, fully cored, boreholes. Some of the work undertaken for each of these disciplines will be described in relation to both projects.