n 2010 BAUER Foundations Canada Inc. (BFCA) was approached to execute a cut-off wall that was approx. 900m long and up to 13m deep at the South West Sand Storage – Syncrude Site. The main criteria was the execution during severe winter conditions from November to March.
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 mixture as usually used. The solution that BFCA utilized 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 0.5m to 1m of frozen soil had to be removed to create a small trench to contain any overflowing suspension. BFCA’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, the slurry line had heated connections and insulation wrapping the line. The mixing was performed by a RTG19 with a BCM10 cutter attachment. To speed up the production process of the cutter pre-drilling was performed by a BG18 and a continuous auger.