Boliden fjellhaller 23, 24

• Client/Design: Boliden Odda AS
• Contractor: Metrostav Norge AS
• Construction period: 08/2024 – 05/2026

Excavation of mountain caves nr. 23 and 24 represents new phase of extension of underground system of Boliden Odda AS company. Waste from the zinc production in local factory is stored in the mountain caves. Waste is being brought there in the pipes, the transport medium is water that circulates in a closed circuit.

Halls are 250 meters long, 30 meters wide and up to 75 meters high. Each of the halls has a volume of 400 000 m3. Halls are excavated in five levels, the first three levels are excavated using the tunneling drill and blast method, the last two levels are excavated using the quarry method.

Besides mountain caves nr. 23 and 24 Metrostav Norge AS extends also the network of access tunnels in total lenght of 540 meters and excavates new mercury storage hall with the lenght of 120 meters and volume of 22 700 m3. Total excavation volume is 881 000 m3. Most of the blasted material is being dumped on the bottom of the fjord from floating barges.  

• Technologically difficult excavation, horizontal and vertical division of faces 
• Use of vertical drilling excavation method in tunnels
• Extensive system of existing tunnels, complicated system of ventilation and media distribution
• Use of floating barges. Excavated material is being dumped on the bottom of the fjord
• Securing works above tipping windows – prevention of avalanches and rock falls during winter time