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WJ News

Latest News and Updates from WJ Groundwater and across the Industry.

Dewatering and Groundwater Treatment

Dan Carpenter October 27, 2023

Residential Dewatering and Treatment

Whilst much of WJ Canada’s work has been on transport and infrastructure projects, we are equally at home providing groundwater control services on residential projects.

Complex Conditions

For this project WJ were engaged to provide an upgrade of an existing dewatering system to meeting unexpected groundwater conditions on site, and to ensure the works could take place successfully. When WJ were brought on board we were immediately met with a complex geology consisting of distinct aquifers and water flow conditions. Thick, highly permeable, sandy aquifers were present, with low permeability peat layers on the east side of the site.

Dewatering and Treatment

WJ’s flexible dewatering solution was successfully implemented to accommodate the varying groundwater conditions by reducing the natural groundwater levels by 10m in a 13m deep excavation.

In addition to the dewatering system, a water treatment system was also upgraded to accommodate the high flows of around 1,000,000.00 l/day, as well as treating the water so they iron rich water (100mg/l) were clear by the time they had passed through the various media filters and bag vessels (which included automatic backwash operations), without interrupting the onsite dewatering works.

…and monitoring

A remote monitoring system covering all dewatering and water treatment system components and including water level sensors were also installed within the scope of this project. Thus, all the details of dewatering and water treatment works happening on site were instantly visible and traceable.

WJ wellpoint installation at UOIT September 2019

Emergency Residential Condo & Commercial Development Dewatering

Dan Carpenter October 27, 2023

Residential Condo and Commercial Developments

Residential Condo and Commercial Developments are bread and butter to WJ and have formed a large chunk of our dewatering both at home in and Toronto, as well as overseas.

Emergency Call-Out

This project was however a little different as WJ were engaged to provide emergency remedial response work. The existing dewatering contractors had installed an external perimeter dewatering system, alongside localised internal dewatering, but this system was struggling to achieve the required drawdown for the final elements of the excavation.

Successfully Dewatered

WJ stepped in using our unique well point system, including utilising our specialised drilling methods to install included wellpoints through the caisson piles. Our small drilling rigs allow us to handle intricate projects requirements and access near impossible spaces. With our unique systems and equipment, the required drawdown has successfully been achieved.

Dewatering for Sump Installation

Dan Carpenter October 27, 2023

Dewatering for New Sump and Drainage Installations

If there is a requirement dewatering in a complex or challenging environment then WJ Canada are the ideal people to get in touch with, and this was the case on a recent residential development.

An existing residential tower development required the installation of an upgraded permanent drainage and sump system within the confines of the existing basement, in order to allow further development of the site. The client decided there was a need to install twin prefabricated sumps beneath the existing second level underground parking garage.

Unique Challenges

This provided a number of unique challenges – difficult access, restricted headroom, working in close proximity to structural pillars and footings of the existing building, as well as working in a very high yielding loose sand aquifer.

Successfully Dewatered

WJ successfully used one of our drilling set-ups, specifically modified to work on limited access and headroom sites, to install two perimeter vacuum wellpoint dewatering systems around the sump excavations. High yielding vacuum wellpoint pumps were used in tandem to dewater each of the excavations to their target drawdown levels, allowing easy and seamless excavation, placing of the new sump, and backfilling by the installation contractor. There were strict requirements in place to ensure that the groundwater pump was free of sediment to mitigate the risk of ground settlement (which was a significant concern at the site), so this was monitored by a third party throughout the installation and running of the system, fortunately the works were carried out successfully.

How WJ can help you

WJ offer solutions for all types of geology and can meet the challenge of working within limited spaces that have sensitive requirements.

Finch West LRT Project, Toronto

Dan Carpenter February 8, 2021

The Dewatering Vendor of Choice for Toronto LRT Projects

The success of the Eglinton Crosstown LRT (Light Rail Transit) project (also known as Line 5) in Toronto, where we have provided dewatering services to great effect on 12 of the 14 stations, has led to WJ becoming the dewatering vendor of choice for large LRT projects in the city.

Finch West LRT

Building on the success of this project, WJ have recently begun work on the Finch West LRT project. The Finch West Project (also known as Line 6) continues the expansion of public transit services in Toronto and is expected to carry some 40,000 passengers per day by 2031. Our initial works on the project will cover the two new underground station that are due to be constructed: the new terminus at Humber College and the new interchange terminus at Finch West, where the new line will connect with the Line 2 extension to York University.

Finch West Station

The Finch West Station includes a deep connection to the existing subway station and an underground track crossing – in short a deeply complex project, that will require the installation of deep wells, wellpoints and eductor wells. Fortunately these types of projects are second nature to WJ and perfectly demonstrate our creative and flexible approach to providing successful and efficient dewatering solutions that we have shown on thousands of project in Canada and elsewhere across the globe!

Humber College Station

The Humber College station, located adjacent to Highway 27 will be another opportunity to demonstrate many of the dewatering techniques that were used to great effect on the deep excavations of the Eglinton Crosstown project.

We are proud to be given the opportunity to contribute to this exciting project, and the continued expansion of public transit projects in Toronto, and look forward to its successful completion, and having the opportunity to hop on board!

LOCATION: Toronto
CLIENT: Metrolinx

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.”

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.

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.

Dubai International Airport

Neil.Coulter December 11, 2013

Since it opened in 1960, passenger numbers at Dubai International Airport have grown and grown, on average by 15% a year.