Swiss mountain village of Brienz gets expensive drainage tunnel

Brienz will receive a CHF 40 million drainage tunnel. The structure, almost two kilometers long, aims to prevent the village from sliding further into the valley.

The Swiss mountain village of Brienz is getting a CHF 39.8 million (EUR 41.27 million) drainage tunnel to slow further landslides in the valley. The Albula/Alvra municipal assembly approved the corresponding loan on Friday night with no opposing vote. But the municipality of 1,300 inhabitants does not have to shoulder the loan alone. The city council expects contributions from the federal government and the canton of Graubünden amounting to 90% of the total costs.

Brienz has recently made international headlines because the village was threatened by a landslide that could have buried it. Little is known outside Graubünden that the village itself sits on unstable rock and is sliding down the valley at ever-increasing speed. An area of ​​about three square kilometers is shifting more than a meter a year.

Sliding speed must be reduced

Experts assume that increased underground water pressure is the main cause of landslide movement. The drainage tunnel aims to reduce this pressure and greatly reduce the landslide speed of the village in the long term. Ideally, this would also have a positive effect on the rock massifs on the mountain above the village, which are in danger of collapsing. An exploratory tunnel measuring 635 meters in length has already been built and exceeded the expectations of the geologists involved. Sliding movement over this tunnel has dropped by almost half.

The now approved drainage tunnel is a 1.65 km extension of the exploratory tunnel, resulting in a 2.28 km long drainage system. From this, more than 100 drainage holes are also created. The tunnel itself will be almost five meters high and can be traversed by trucks. A construction period of 42 months is foreseen for the construction of the drainage tunnel with drainage. The earliest possible start of construction is March 2024. (APA)