National Contractor Archives

Eductor systems for PATH Toronto

WJ Group Admin September 9, 2020

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

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.”

WJ wellpoint installation at UOIT September 2019

Eductor wells 543 Richmond Condominiums

WJ Group Admin August 27, 2020

Our first residential dewatering in Canada

WJ have a long established history of providing dewatering for residential developments in the UK, Middle East and mainland Europe. Whilst 543 Richmond Condominiums will for many just be another block amongst the forest of condos in downtown Toronto, it will always be special to WJ as our first residential dewatering project in the country.

The challenge

As with all city centre projects across the globe, access and space is always at a premium. In the case of the Richmond Condos project, the footprint of the excavation took up almost 100% of the site. This meant space for the installation of dewatering wells and storage of pumping plant and equipment was sparse. However, WJ showed our trademark flexibility by working with the project client to locate our plant, equipment and materials to maximize the available resources.

Installing eductor wells

The programme of works was key on this project. In order to dewater Toronto’s characteristic silty sandy lake deposits, WJ mobilized two drilling rigs from our extensive, modern drilling fleet to install 55no eductor wells around the perimeter of the excavation.

A successful result

The highly stratified ground conditions, of predominantly low permeability soils with occasional higher permeability layers, made this project challenging… but we love a challenge at WJ and, as of summer 2020, the pumping and construction works are successfully underway, with the first apartments scheduled to open in 2022.

LOCATION: Toronto
CLIENT: 543 Richmond Condominiums
DEVELOPER: Pemberton Group

“543 Richmond Condominiums will always be special to WJ as our first residential dewatering project in the country.”

Wellpoints at UOIT, Oshawa

WJ Group Admin August 27, 2020

The University of Ontario Institute of Technology in Oshawa, located approximately 70km east of WJ’s Head Offices in Toronto, is one of Canada’s leading universities. It was the site of one of our earliest projects in the region not associated with the Crosstown LRT works.

An unexpected dewatering requirement

Groundwater control strategies are conventionally developed during the early planning stages of a project. But it’s not uncommon for unexpected groundwater to be encountered on a project where dewatering was not initially anticipated to be required. In these instances it’s important to be able to mobilise a reliable dewatering contractor to site at short notice to minimize the risk of potentially costly programme delays.

During the early construction works for a new building, housing the Faculty of Health Sciences, Office of Student Life and the new Ontario Tech University Students Union, the client unexpectedly encountered groundwater and got in touch with WJ.

Our response

Fortunately due to our extensive fleet of installation and pumping plant and equipment (not to mention talented and experienced staff!) we were able to prepare an appropriate dewatering design for the works, installation of the system and achieve the desired drawdown all in a few weeks, to the relief of the client.

The approach – innovative wellpoints

The project would comprise a wellpoint dewatering system to dewater the bulk excavation and a deeper central sump structure. Normally an excavation of this depth, size and in these ground conditions would require an expensive perimeter eductor dewatering system.

However with good drilling techniques from our ‘Baby Giraffe’ drilling rig, WJ’s innovative wellpoints, and clever positioning of the pumping equipment, we were able to able to avoid having to install an energy inefficient and space hungry eductor system. This ultimately saved our client $1,000s!

This 100no wellpoint system, was able to achieve drawdown significant enough for the client to dig to 5m depth in dry conditions; a depth which would not normally be considered feasible with this type of system.

Communication was key

Close and regular liaison with the client was vital on this project due to the nature of the works. As the new buildings would be linked in to existing and active buildings on site, space was of a premium.

Additionally the phasing of the construction works had been planned prior to the requirement for dewatering being determined. A deep central sump excavation was amongst the first to be scheduled and as a result a big drawdown was required initially prior to the full system being installed.

Installing the wellpoints with the Baby Giraffe

WJ chose to use the ‘Baby Giraffe’ for both phases of wellpoints. Its extendable mast allowed us to install wellpoints without the need for the construction of excavating rig platforms or access ramps, saving further time and unnecessary expense.

You can learn more about this project on the Ontario Tech University website.

“We were able to able to avoid having to install an energy inefficient and space hungry eductor system, saving our client $1,000s”

LOCATION: Oshawa
CLIENT: Ontario Tech University

Provost Driver Court, Renfrew

Dan Carpenter October 9, 2017

This contract took WJ to Renfrew, in the suburbs of Glasgow, not far from our Scottish Office in the Scottish capital, to help contribute to an award winning project.

Bromley South Central, London

Dan Carpenter October 9, 2017

This contract took WJ to Bromley, in the heart of South London, to take part in a new major regeneration project.

Royal Hospital For Sick Children, Edinburgh

Dan Carpenter October 9, 2017

The Royal Hospital for Sick Children has been based on it’s existing site in the heart of Edinburgh since 1895, however in 2005 it was decided by the local NHS Trust that a more modern facility should be constructed adjacent to the existing Edinburgh Royal Infirmary at Little France on the south-east edge of the city.

Eductor systems for PATH Toronto

PATH Toronto – the background

Phase 1

Meeting project constraints

Ahead of schedule

Eductor wells 543 Richmond Condominiums

Our first residential dewatering in Canada

The challenge

Installing eductor wells

A successful result

Wellpoints at UOIT, Oshawa

An unexpected dewatering requirement

Our response

The approach – innovative wellpoints

Communication was key

Installing the wellpoints with the Baby Giraffe

Provost Driver Court, Renfrew

Bromley South Central, London

Royal Hospital For Sick Children, Edinburgh

Lodz High Speed Rail Interchange, Poland

Crossrail Stepney Green Shaft & Junction

Crossrail Station, Canary Wharf

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