Testing Programme in Deep Boreholes Drilled in Sediment-Covered Crystalline Rocks in Northern Switzerland

Abstract

In the course of a regional geologic investigation programme characterising a potential region for HLW disposal, six deep boreholes with a maximum depth of 2482 m have been drilled and tested. For one of these boreholes, the Bottstein well, which penetrates 300 m of Mesozoic sediments and 1200 m of granitic rock, the comprehensive testing programme is described. Extensive geophysical logging was performed and attempts were made to correlate the results with bore core observations. The most extensive efforts were devoted to hydraulic testing and groundwater sampling for detailed hydrochemical and isotopic measurements. For some investigations, parallel tests with differing methods were performed in order to allow a specific comparison and optimisation of further site investigation programmes.