Rio Tinto has almost completed the second tunnel at its Kemano T2 hydropower project in British Columbia, Canada, which it said will ensure a long-term power supply for the smelter.
The company said the tunnel boring machine cut 7.6 kilometres through the rock in remote mountains over 30 months, completing the route for a 16-kilometre tunnel that began in the early 1990s.
Kemano T2 Project Manager Alex Jones described it as a milestone towards finishing the tunnel and securing the long-term reliability of hydropower for Rio Tinto's smelter in Kitimat, a producer of carbon aluminium.
"Boring this tunnel is a highly-skilled and technical feat that has been achieved in an extremely remote location that is only accessible by air or sea," Jones said.
The company said the tunnel will be filled up with water in the middle of 2022, and it expects to complete the project during the second of the year.