Wellenberg geological synthesis report 1996. Results of the investigation phases I and II. Appendices

This report synthesizes the results of all the investigations performed at the Wellenberg site to date. The investigation programme consisted of seven deep boreholes, several reflection and refraction seismic campaigns, piezometer and shallow exploratory boreholes and a series of geological field studies. The aim of the investigations was to obtain a sufficiently extensive geological database to allow a thorough evaluation of the site suitability. The most important questions in this respect relate to the long-term safety of a planned repository. Consequently, the concrete investigation objectives were directed primarily at fulfilling performance assessment needs. Additional objectives included demonstrating engineering feasibility and providing a reliable geological database for planning future underground investigations. Completion of the surface-based investigations represents an important milestone for the geological site characterisation. A significant improvement on the current level of understanding of the site is possible only through the planned exploratory drift which will provide direct access to the disposal zone. The aim of the present report is to document the investigations carried out at Wellenberg to date, to present and discuss evaluations and analyses of the resulting data and to explain the conclusions reached. Considerable importance is attached in this connection to presenting in a transparent and traceable manner the synthesis methodologies used. (author) figs., tabs., refs