Nagra drilled the Bülach borehole between April and November 2019. The drill site at Herrenwies will now be dismantled, which will take two months. The land will be recultivated to allow agricultural use to resume. All that will remain for the time being is the so-called rig cellar which is a few square metres in size. The borehole will be sealed safely at the top but not yet infilled. This leaves open the option for Nagra to install measuring equipment in the hole. «The measuring equipment will allow us to collect further data underground for years or even decades», explains Philipp Senn, Head of Public Affairs at Nagra.
The cooperation with the town of Bülach, the local residents and the population in the region proved to be both congenial and constructive. «We are particularly pleased that around 1500 people took the opportunity to look over our shoulder during drill site tours and to discuss relevant issues with us», says Senn.
Bülach is located in the Nördlich Lägern region, one of three potential siting regions for a deep geological repository. To obtain a comprehensive picture of the geology of the region, two further boreholes will be drilled in the community of Stadel from the end of the year. There will also be the opportunity in Stadel for interested persons to visit the drill site.
With the deep boreholes in the regions Jura Ost, Nördlich Lägern and Zürich Nordost, Nagra is investigating the composition of the Opalinus Clay, as well as its tightness and thickness. The Opalinus Clay is the host rock in which the repository will eventually be constructed.