Nördlich Lägern – the siting region for Switzerland’s deep geological repository
The “Nördlich Lägern” region is situated in the Cantons Zürich and Aargau to the north-west of Bülach. Investigations show that the subsurface in this region can safely contain radioactive waste. Nördlich Lägern is the most suitable site and has the largest safety reserves.
In the future, Switzerland will dispose of its radioactive waste in a deep geological repository. This will comprise both underground and surface facilities.
This is what the repository could look like
Geology is the decisive factor
The decision on where to construct the repository depends on geology. Experts worldwide agree that a deep geological repository is the safest option for the long-term disposal of radioactive waste. The waste will be enclosed in rock formations at a depth of several hundred metres.
The most important of these rock formations are the Opalinus Clay and the clay-rich over- and underlying rocks. They can also be found in the Nördlich Lägern region where they have favourable properties.
In September 2022, Nagra proposed Nördlich Lägern as the site for Switzerland’s deep geological repository. Nördlich Lägern is the site with the largest safety reserves.
Learn more about the proposed site
Access to the repository in Stadel
As part of the federal government’s Sectoral Plan for Deep Geological Repositories defined in 2008, Nördlich Lägern was investigated in great depth as one of the potential siting regions. We have detailed information on the properties of the rocks and on how much space is available for a repository.
The access to the deep geological repository is to be constructed in the Haberstal area in the community of Stadel. However, the waste encapsulation plants will not be located directly on site but at the interim storage facility in Würenlingen.
Nagra submitted the general licence application for a deep geological repository in Nördlich Lägern in November 2024.
Learn more about the general licence
Visualisation of the surface facility at Haberstal
A brief look back
The geological subsurface in Nördlich Lägern was explored and characterised using numerous investigation methods, including seismic and Quaternary investigations as well as deep boreholes. The same investigations were also carried out in the two other geological siting regions remaining in Stage 3 of the Sectoral Plan: Jura Ost and Zürich Nordost.
In winter 2016/17, large-scale 3D seismic measurements were carried out to obtain an image of the subsurface in Nördlich Lägern. This method can be compared to medical ultrasound images or an echo sounder used on ships. The seismic images we obtained provided important information on the structure of the rock formations. We were also able to identify the presence of geological fault zones and assess the space available for a repository.
In addition, five deep boreholes were drilled in Nördlich Lägern. These reached a depth of several hundred metres and went far below the Opalinus Clay that will safely confine the waste. By drilling these boreholes, we were able to obtain samples from various rock layers and determine their properties. Four boreholes were drilled in Nördlich Lägern during the last deep borehole campaign from 2019 to 2022. The Weiach borehole dates back to 1983.
Investigations showed that the Opalinus Clay, but also the rock formations lying directly above and below it, are very tight. The deep boreholes also revealed the depth at which the individual layers are located.
Nagra Technical Report NTB 88-08 on the Weiach exploratory borehole.
Read report
Deep boreholes in Nördlich Lägern
Bachs-1 borehole
The Bachs borehole was the fourth deep borehole to be drilled in the Nördlich Lägern siting region as part of Stage 3 of the site selection process.
Stadel-2 borehole
The Stadel-2 borehole was the third deep borehole to be drilled in the Nördlich Lägern siting region as part of Stage 3 of the site selection process.
Stadel-3 borehole
Stadel-3 was the second deep borehole to be drilled in the Nördlich Lägern siting region as part of Stage 3 of the site selection process.
Bülach borehole
Bülach was the first deep borehole to be drilled in the Nördlich Lägern siting region as part of Stage 3 of the site selection process for a deep geological repository.
To provide post-closure safety, the emplacement rooms of a deep geological repository that hold the waste must be located sufficiently deep below ground. Only then is the repository safe from erosion caused by rivers and glaciers. Traces of past erosion processes are also visible in the Nördlich Lägern siting region. Glaciers cut deep troughs into the landscape, and glacial advances will also occur in the future.
To learn more about the impact of glaciers and rivers and to develop future scenarios, we conducted Quaternary investigations. These allowed us to study the topmost – and our planet’s most recent – rock layer located just beneath the surface. Quaternary investigations primarily include Quaternary boreholes that are drilled to a depth ranging from a few dozen metres to around three hundred metres.
Find out more about the Quaternary boreholes.
Read more
These investigations enabled us to complement and complete the previously obtained knowledge of the geological subsurface in Nördlich Lägern. The same techniques were used to thoroughly investigate the other two potential siting regions, Jura Ost and Zürich Nordost, allowing for an objective comparison of the three regions.
This comparison has shown: the host rock in Nördlich Lägern provides the best protection for the repository from erosion, partly due to its greater depth.
Working together to determine the site of the surface facility
Where will the buildings at the surface and access points for a deep geological repository eventually be constructed? These are questions Nagra has addressed together with the siting regions. Our dialogue partners are the Nördlich Lägern Regional Conference, Cantons Zürich and Aargau as well as representatives from neighbouring Germany. They were invited to express their views on proposals that were published as a basis for collaboration and discussion. By collaborating from this early stage, the responsible Swiss Federal Office of Energy ensures that the needs of the Nördlich Lägern siting region are considered to the greatest extent possible.
When proposing the repository site in 2022, Nagra also announced that the surface facility would be built in the Haberstal area in the community of Stadel. The encapsulation plant will be constructed on the site of the existing Zwilag interim storage facility in Würenlingen. These are the sites for which the general licence applications were prepared. Nagra submitted these applications in November 2024.
There is a report on Nagra’s siting proposal.
Download
Nagra meeting point
Nagra opened its meeting point in Stadel in 2024. Drop in and talk to us about the project of the century of deep geological disposal. You can find us at Zürcherstrasse 6 in 8174 Stadel (across from the Volg supermarket). We are open on Wednesdays and Fridays from 9 a.m. to 5 p.m. and look forward to your visit!
Photos: Beat Müller / Marco Roth Photography / Nagra