The Peribonka dam is located in the heart of the province of Québec, Canada. The project involves the construction of a main earth dam across a main and secondary valley, two main dykes and a hydroelectric generating Run-Of-River station with an estimated capacity of 385 megawatts.

 

Under the main dam body, the construction of an exceptionally deep cut-off wall was required, to create a seepage barrier in highly permeable riverbed alluvia. Bauer was awarded the contract on the basis of an alternative design: the plastic concrete cut-off wall to be completely embedded in the bedrock, a design which avoided any potentially hazardous areas to be sealed by cement grouting. The cut-of�f wall was exceptional by its depth, reaching almost 116 m, and being surrounded by complex geotechnical ground conditions.

 

Bauer commissioned a hydraulic cutter, the CBS CBC 135, the biggest ever manufactured, which included new features and was designed specifically for the construction of the Peribonka dam cut-off wall. Beside the extreme depth of the bed rock, the design was further complicated by the presence of hard rock including granite, with strengths at times in excess of 200 MPa, quasi vertical rock cliffs, rock overhangs, and gullies filled with coarse alluvia, including boulders.

 

Deep Vibrator

Drilling and Grouting Works

Cut-off wall operation at main dam

 

In addition to the cut-off wall construction Bauer provided a complete construction package comprising soil improvement of alluvium and manmade fill material by vibro densification down to depths of 48 m – rock consolidation and contact grouting as well as construction of a grout curtain to depths of up to 150 m by drilling and grouting, and the installation of permanent and temporary dewatering systems.

 

 

Glaciall Gully	Original proposal	Bauer's proposal
	cut-off wall with cement grouting	Cut-off wall fully embedded in rock

 

The plastic cut-off wall constructed in Peribonka has shown that this technique provides solutions for dams in ground conditions which are beyond the limits of other techniques such as cement grouted cut-offs.

 

 

Scope of work:

 

• Earthworks
• Water Well Installation by Bauer BG Drill Rigs
• Drilling and Grouting with Bauer small diameter drill rigs
• and Bauer batching and pumping plants
• Soilimprovement with Bauer Vibroflotation System
• Cut-off wall by Bauer Cutter and Clamshell