BAUER Foundations Canada Inc. was approached to execute a cut-off wall that was approximately 900m long and up to 13m deep at the South West Sand Storage (SWSS) at the Syncrude site. The main criteria was the execution during severe winter conditions, as the Fort McMurray region is known for its cold conditionsfrom November to March. The construction of the wall in these winter conditions created many unique problems with handling equipment and materials that Bauer Foundations Canada had to solve.
A common soil-bentonite wall was not possible due to the freezing of the slurry in the open trench. Frost would also prevent the mixing of the excavated material with the slurry and bentonite powder to create the homogenous soil-bentonite mixtureas usually used. The solution that Bauer Foundations Canada utilized for this project was a CSM wall. The Cutter-Soil-Mixing (CSM)-method allows the bentonite cement slurry to be injected directly into the soil at the location of the treated wall.
Only the first 0.5 m to 1 m of frozen soil had to be removed to create a small trench to contain any overflowing suspension. Bauer Foundations Canada’s solution for handling the slurry preparation equipment was to set up the mix plant inside a large heated tent. To guarantee that the slurry would not freeze while being pumped from the tent through a heated booster station on to the machine up to 500m away, the slurry line had heated connections and insulation wrapping the line. The mixing was performed by a RTG 19 with a BCM 10 cutter attachment. To speed up the production process of the cutter pre-drilling was performed by a BG 18 and a continuous auger.
This enabled Bauer Foundation Canada to treat the sandy soils and to finish the project on time allowing the client to continue operations without any impact to the production.