Challenging tunnel work in Odda

Tunnel work can also be halted due to bad weather. On Thursday, October 31, at 7:00 PM, work in the tunnel halls in Odda had to stop for 17 hours. The reason was prolonged rainfall, which caused landslides and flooding on roads in several areas, blocking both access routes to the entrances.

Tunnel excavation for the project began on August 13, 2024, and so far, we have managed to excavate almost all the access tunnels and the most challenging parts of the entrance to the first tunnel hall, where we have struggled with steep gradients of up to 21.5%. The work on the tunnel hall openings has been technically very challenging, not only due to the steep inclines but also because of the short distance to Boliden’s existing facilities, which remain in continuous operation. The final challenge was the first blasting in the “HG hall,” where the excavation was only three meters away from Boliden’s active installations.

Another interesting feature of this project is that the rock mass is transported through the tunnel system and dumped into the sea via barges. This process must be carefully monitored and managed logistically, as there are strict regulations on where on the seabed the material can and cannot be spread.

In total, we have excavated 91,100 m³ of the planned 881,400 m³.