Construction of the exploratory tunnel under Brienz slip in the Graubünden municipality of Albula/Alvra has begun. The tunnel explores the possibilities of draining the Brienz slide from below and thus slowing it down. The work is expected to take one and a half years and cost around 14 million francs.
With the first blast, mining work on the exploratory tunnel began on Monday under Brienz slip. The 650-meter long tunnel is built in solid rock under Brienz Rutsch. From the tunnel, numerous holes are drilled into the rock and the overlying slippery mass, through which mountain water can flow off into the tunnel. The exploratory tunnel is intended to show whether “deep drainage” can lower the water pressure in the rock and remove water from the subsoil of the village of Brienz/Brinzauls.
The entire village of Brienz/Brinzauls is currently sliding downhill around one and a half meters per year. It stands on a slippery mass of up to 150 meters thick. If it is possible to drain it, experts hope that the landslide will slow down or even come to a standstill. The exploratory work that has now begun is intended to provide information on these questions. If the tests produce positive results, the tunnel should be extended and operated in the long term.
The costs of building the exploratory tunnel amount to around 14 million francs. 90 percent of this is financed by the federal government and the canton of Grisons, the rest remains with the municipality of Albula/Alvra and the owners of public infrastructure in the affected area.
Technical renovation of the Brienz slide
In a small celebration, Grisons district president Mario Cavigelli, municipal president Daniel Albertin and project manager Daniel Kohler from the tunnel construction company Frutiger paid tribute to the importance of the tunnel and that of the miners who will drive it into the mountains in the coming months. Father Don Federico blessed a figure of Saint Barbara, who, as a patron saint of miners, is supposed to contribute to their safety.
The municipality, the canton of Grisons, the responsible experts and the affected population have high hopes for the effect of deep drainage through the tunnel.
This “technical repair” of the Brienz slide should be carried out as quickly as possible, as the high slide speed is causing more and more damage to the village and even a rock slide cannot be completely ruled out. The planning, approval and preparation work was therefore carried out within just one year, which corresponds to around a quarter of the normal time. Construction will now run from Monday to Friday in two shifts a day from 6 a.m. to 11 p.m., and the tunnel will be exploded. Most of the excavated material is recycled and reused.
Some of it is finally stored in the Crappa Naira Brienz municipal landfill.
Christian Gartmann has been Communications and Media Officer for the Municipality of Albula/Alvra for Brienz Rutsch since 2019.