British Columbia Hydro and Power Authority (BC Hydro) is building the third hydro-electric power plant on the Peace River in northern British Columbia. The dam is being constructed nearby Fort St John.
To enable the actual dam construction a series of cut-off wall structures was required. In order to meet the specified construction schedule, cut-off wall works had to be executed through the winter months facing the harsh winter conditions of Northern Canada. Temperatures during wall installation were as low as - 25° Celsius. The main cut-off wall construction works were carried out in multiple shifts 24 hrs/day and 7 days/week during August 2016 and November 2017.
BFCA's scope of work comprised the installation of four cement bentonite cutoff walls at various locations along the new proposed dam. Up to three excavation units (both hydraulic and rope grabs) were mobilized for the project. 80,000m² cut-off wall were installed over a total length of approx. 3.7km. The wall had to be embedded into the weak sandstone/mudstone rock. In places up to 3.8 m rock embedment was achieved to reach the designed wall toe levels. The panel excavation reached a maximum installation depth of approx. 25m.