Case Study: Installation of a Soil-Cement-Bentonite Groundwater Cutoff Wall in Argentia, NL

ABSTRACT: In 2014, Canada Geo-Solutions Inc. (CGSI) completed a deep groundwater cutoff wall on the Avalon Peninsula of Newfoundland & Labrador using the slurry trenching installation method with a soil-cement-bentonite backfill. The objective of the project was to cutoff groundwater flow from the adjacent bay so that a deep, large excavation, approximately 250 m long x 250 m wide x 19 m below sea level, could be effectively dewatered for use as a graving dock for the construction of an offshore oil rig structure. The cumulative length of cutoff walls installed was 773 linear meters with depths up to 40 m below ground surface and a total area, length x depth, of 29,712 m2. The performance requirements for the installed cutoff wall included a maximum hydraulic conductivity of 5x10-7 cm/s and a minimum shear strength of 100 kPa.