Arbeitsbericht NAB 12-50

Geotechnical characterization of core samples from the geothermal well Schlattingen SLA-1 by LMS/EPFL

The Laboratory for Soil Mechanics (LMS) of the Swiss Federal Institute of Technology in Lausanne (EPFL) was requested by NAGRA to perform a geomechanical testing program on core samples extracted from a deep geothermal well near the village of Schlattingen in the Molasse Basin of Northern Switzerland. The laboratory studies are aimed at characterising three candidate host rock formations for the disposal of radioactive waste, namely the Effingen Member, the so-called 'Brown Dogger' (stratigraphic sequence of Callovian, Bathonian and Bajocian age) and the Opalinus Clay. The investigation programme comprises basic geotechnical identification tests, determination of the water retention behaviour and hydromechanical tests. The results of the laboratory investigations will feed in Nagra's data base on hydrogeological host rock properties. The electronic data base is enclosed in Appendix A. After completion of the geotechnical characterisation, a mineralogical analysis was performed on the left-overs of the tested core samples. The results of the mineralogical investigations are presented in appendix B.