BAUER Foundations Canada was awarded the contract for the construction of 138 piles, with 2,000 mm diameter permanent liners and a rock- socket of 1,850 mm diameter and 4 m/7.1 m length for the Nouvelle Autoroute A 30 bridge in Beauharnois near Montreal, Quebec. The length of the piles varies to 24 m depth both on land and on water with a riverbed below 4.2 m to 13.6 m of water for the piles on the canal.
The area of Beauharnois is part of the Saint Laurent geologic region and its bedrock is made of dolomitic and quartzitic sandstone, a very hard and highly abrasive rock. The decision was to use the technique with the roller bit barrels. These barrels allow withdrawing large diameter cores from the ground by grinding slowly the rock on periphery and let the two powerful BG 28 and three BG 40 expose their potential. The offshore piles are drilled by two BG 40 on a customized barge with several additional tools.
Where the challenge is getting bigger is that more than half of the piles are to be realized offshore from barges on the Beauharnois canal and mainly without any overburden to maintain the permanent liners. Also the water current there is very strong, so all procedures had to be adjusted. In fact the canal is the main point of the job site, drawing all attention as a race against rock and winter was engaged.