Hydropower tunnels

Contracting services

Ice plug from surface

Geofrost provides ice plugging of water tunnels upstream the first gate, in order to empty the tunnel for water and carry out refurbishment works in a safe manner in a dry tunnel.

Ice plug is used because a cofferdam is not always easy to establish. It may be due to topography, regulations for the lake, or large values being lost for the owner if the water level is lowered.

Ice plug from waterside

Geofrost may install the ice plug through the water intake if the headrace tunnel is a pipe or an intake structure that preferably should not be drilled through, or it is not practical to drill into the tunnel.

The ice plug has high reliability and is frozen into the surronding rock or concrete lining. The ice plug is monitored as long as it is functioning and detailed capacity calculations are always part of the design.

Cofferdam

Geofrost provides a waterproof core in rock fill dams to create a cofferdam. Drilling is done through the rock fill and further down through permeable layers and fractured rock, ensuring a completely impermeable cofferdam.