Geological boreholes provide a direct insight into the underground geological environment and its structure. These exploratory boreholes are also called deep boreholes.

Up-to-date information on the deep boreholes running since early 2019 can be found on the website “deep boreholes” (in German).

Two drilling techniques are widely used:

When using a roller bit, the rock is crushed at the bottom of the borehole. A fluid that flushes the bits of rock (drill cuttings) to the earth's surface is pumped through the drill rod. This drilling fluid is circulated in a closed cycle.

The more complex cored boreholes only crush the rock surrounding the borehole. The so-called drill core inside the core drill bit remains intact. The drill core can be removed and transported to the earth's surface where the rock can be investiagted more closely.

To complement these investigations, various borehole measurements, so-called logs, as well as further hydrogeological and rock-mechanical tests are conducted.

To date, Nagra has drilled around 1000 to 2500 metres of borehole in Northern Switzerland as part of the investigation programme for the demonstration of disposal feasibility (Entsorgungsnachweis). The boreholes are:

Böttstein 1501 meters (1982 to 1983)
Weiach 2482 meters (1983)
Riniken 1801 meters (1983 to 1984)
Schafisheim 2006 meters (1983 bis 1984)
Kaisten 1306 meters (1984)
Leuggern 1689 meters (1984 to 1985)
Siblingen 1522 meters (1988 to 1989)
Benken 1007 meters (1998 to 1999)


Exploration applications

In accordance with the Nuclear Energy Act, deep boreholes conducted by Nagra require a permit granted by DETEC (Federal Department of the Environment, Transport, Energy and Communications). The Federal authorities examine the applications in cooperation with the corresponding cantons. Once the permit for a deep borehole has been granted, the drill site can be built. The first borehole went into operation in early 2019.

With a view to Stage 3 of the Sectoral Plan process, Nagra submitted applications for permits for eight exploratory boreholes in each of the siting regions Jura Ost and Zürich Nordost in September 2016. The applications for the Nördlich Lägern region followed in August 2017.

The applications were open for public inspection in the affected communities in the Jura Ost region between 27th February and 28th March. The inspection period in Zürich Nordost ran from 13th March until 26th April. The public inspection in Nördlich Lägern began on on 1st November 2017. All public inspections were completed on 16th January 2018. On 21th August 2018, the first three permits (Bülach, Marthalen and Trüllikon 1) have been granted by DETEC. To date, DETEC has approved twelve of the 23 applications submitted for exploratory boreholes. These are: Bözberg 1, Bözberg 2, Bülach, Effingen 1, Marthalen, Remigen 1, Rheinau, Riniken 2, Stadel 2 Trüllikon 1, Trüllikon 2 and Trüllikon 3. Other permits are expected in the coming months.

The planned exploratory boreholes in the Jura Ost region are Zeihen, Effingen 1, Riniken 2, Remigen 1, Remigen 2, Bözberg 1, Bözberg 2 and Effingen 2.

The planned exploratory boreholes in the Nördlich Lägern region are Weiach, Bülach, Stadel 1, Eglisau, Stadel 2, Glattfelden, Stadel 3.

The planned exploratory boreholes in the Zürich Nordost region are Uhwiesen, Laufen, Trüllikon 1, Trüllikon 2, Rheinau, Dachsen, Marthalen, Trüllikon 3.

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