Shoring was required at this site to allow excavation immediately adjacent to a railway line and to provide façade support for a historical building. In order to install the support for the historical façade it was necessary to drill soldier piles and tiebacks inside the existing building. Special precautions were also required for drilling of soldier piles for the façade support located adjacent to an access ramp for the Gardiner Expressway.
The tower portion of the structure was supported by 87 caissons founded on shale. Diameters ranged from 30″ to 72″. The caissons were installed below the water table. Liners were advanced using a vibratory hammer mounted on a service crane. Drilling of the caissons were completed by a Tauras XL track mounted drill rig.
A new below grade storage area was added to the building after the stadium was close to completion. In order to allow excavation piles were installed from within the existing building using low headroom drilling equipment. Excavation below the existing slabs was carried out using front end loaders and lagging was installed between the soldier piles. In order to reduce the future water penetration and pumping requirements below the slab The Anchor Group installed a grout curtain along the perimeter of the shoring. A series of 4″ diameter holes was drilled adjacent to the shoring. Grout was pumped into the holes to provide a permanent barrier against future water flow.