PATH Toronto – the background
Torontonians have long considered near incessant construction on the arterial roads of the city a part of everyday life in a vibrant and ever growing metropolis.
In order to try and minimize this disruption and as part of the development of the new lake front South Core district, a new pedestrian tunnel was required to be constructed underneath York Street, forming part of the PATH pedestrian walkway system that spans more than 30km of downtown Toronto.
Phase 1 of the new tunnel project, under the southbound lanes of York Street, was beset by extensive issues with the dewatering contractor unable to control the seepage flows in to the excavations. This lead to project delays and frustrations for commuters, the City and the General Contractor. One of the most important skills for those in the construction industry is learning from previous projects, therefore for the second Phase of the project, under the northbound lanes, the client was determined to recoup the lost time and therefore adopted a different approach to the project – part of which involved getting WJ on board!
Meeting project constraints
The General Contractor, PCL, the second largest in Canada, chose to partner with WJ for the tunnel dewatering works upon the recommendations of the structural consultants for the project.
Due to the nature of the site, a small compact rig with a capability of drilling with water flush was essential, therefore we used our trusty SM5 drilling rig to install an eductor dewatering system in Toronto’s characteristic low permeability silty sandy lake deposits which overly the deeper bedrock.
The eductor system was chosen as, based on our extensive experience of working in downtown Toronto, it is best suited to the generally low permeability soils with occasional high permeability layers that are generally encountered.
Ahead of schedule
This installation method and system was so successful we were able to complete our works AHEAD of schedule, and this, coupled with the absence of problematic groundwater in the challenging reclaimed land of the South Core district, enabled the client to make up much of the time lost during the first phase of the works.
- LOCATION: Toronto
- MAIN CONTRACTOR: PCL
“This installation method and system was so successful we were able to complete our works AHEAD of schedule.”