Excavating saturated, loose soil can negatively impact nearby facilities when building underground parking or other below-surface structures. The River Green residential development in the municipality of Richmond, BC has ground conditions of coarse grained alluvial soils and high groundwater elevation, and is located immediately adjacent to the Richmond Olympic Oval, one of the most high profile buildings in the city and part of the legacy of the Vancouver 2010 Winter Olympic Games.
The client required a temporary retaining wall to allow construction of an underground parking structure. This low permeability cut-off wall was also proposed to reduce dewatering volumes during the construction phase, and to minimize the risk of settlement of adjacent structures including the Richmond Olympic Oval.
Golder’s Construction Division proposed the use of Cutter Soil Mixing (CSM) technology to enable construction of a continuous combined low permeability cut-off and retaining wall at the perimeter of the property. The wall extended 350 m around the property and had a depth of 28 m with H-Pile reinforcement at regular intervals.
The CSM technology provided many benefits for this project. The combined cut-off and retaining wall was built within a very narrow footprint (650 mm width) to maximize the area available for development. The CSM equipment has low noise impact and is nearly vibration free for minimal inconvenience to neighbouring stakeholders during construction. Risk to the potential settlement of the Richmond Olympic Oval due to construction on this adjacent lot was mitigated.
Computer software monitored the wall construction in real time. Data was provided to the engineer to ensure ongoing quality control while maintaining that the installation was in line with stringent engineering standards.
Golder’s construction expertise in CSM made it possible to overcome the complex logistics for obtaining wet-grab samples from multiple depths within the panels and placing H-Piles in the fresh panels before the hydration of the panels commenced. Wet grab samples were obtained from the panels to confirm strength and permeability specifications were met.
The project was completed under budget and on schedule, exceeding the performance specifications and with no recordable health and safety incidents.