Cochrane's new bridge across the Bow River is located near the Spray Lake Sawmills Family Recreation Center. Construction started in August 2018 and is one of the largest infrastructure projects undertaken by the Town of Cochrane.
BAUER Foundations Canada Inc. was contracted by PCL Construction Man-agement Inc. to install a total of 30 foundation piles up to a max depth of 24m.
In addition, a secant wall with a retained height of 5m with secant piles up to a maximum depth of 10.5m were also installed.
The soil profile for this area consisted of sand and gravel layers in the top six meters underlain by siltstone, mudstone and sandstone bedrock of up to a strength of 90MPa.
A BAUER BG28 rotary drill rig was mobilized to the site to perform the works.
The foundation piles were located within the riverbed and were concreted us-ing the tremie method. Each pile was drilled with either 1350mm or 825mm diameter permanent casing with a rock socket diameter of 1180mm or 780mm. All piles were reinforced with cages and were concreted with 30 MPa concrete (after 28 days) according to the Alberta Transportation bridge con-struction specifications.
Due to high rock elevation in the site area, adequate water cut-off by means of a sheet pile wall was not feasible. Thus, a secant pile wall cofferdam con-sisting of 880mm diameter piles was constructed as an alternate solution. This allowed the PCL team to construct the pile cap in dry conditions.
All permanent piles were tested with Crosshole Sonic Logging (CSL) method-ology.
The project was completed safely, on schedule, within specifications and qual-ity targets.