Design Archives - WJ Canada

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

Mixed Use Commercial & Residential Redevelopment Project

Dan Carpenter October 27, 2023

Mixed Use 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.

Dewatering in Complex Geology

WJ were engaged to provide a dewatering solution for a mixed use commercial and residential redevelopment project. This would prove to be a complex dewatering project due to the presence of irregular groundwater conditions. The Upper Aquifer would prove to be most challenging requiring close well spacing, whilst monitoring of the Lower Aquifer was undertaken to determine whether the two aquifers were in connectivity.

The Dewatering Solution

The aim of the dewatering system was to target the upper aquifer while monitoring the drawdown in the lower aquifer using well points, and fortunately the system worked well on both accounts.

Internal and external dewatering was undertaking, utilising a compact sedimentation tank (due to the restrictions on space on the site) right next to the TTC box without causing any settlement or disruption.

Problem Solving on site

During the works gaps were encountered in the caisson walls which resulted in an inflow of water right on an interface condition, but WJ was able to quickly suggest a solution which effectively managed the issue to keep the project on schedule without any delay.

WJ continue to tackle challenges head on to ensure our clients needs are met.

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.

LRT Extension Project in Toronto

Dan Carpenter October 27, 2023

WJ keep Toronto Moving

The expansion of the Toronto Light Rail Transit (LRT) network has provided WJ with a steady stream of work since WJ Canada was formed in 2016, work which continues to this day.

Throughout 2022 WJ undertook a variety of pumping tests and other hydrogeological investigations at a number of key sites along the LRT alignment. Alongside these investigatory works, WJ have provided robust dewatering solutions to maximize the drawdown at the Tunnel Boring Machine (TBM) intervention sites.

TBM Interventions

These interventions are locations along the alignment where maintenance is performed on the cutting face of the TBM, and therefore, for safety reasons, zero hydrostatic pressure is required. This requites an extensive and robust dewatering system – something WJ are experts in providing.

In addition to investigatory and dewatering works, an extensive array of groundwater monitoring wells was installed along the alignment to be used for pre-commissioning testing and system monitoring.

LOCATION: Toronto

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.

Sump Pit Completion at Caledonia Station

WJ Group Admin July 18, 2019

The Eglinton Crosstown represents the largest transit expansion in Canada. It will completely change how residents and visitors in Toronto get around this great city. 19 kilometres of new light rail – 10km underground – that starts in the west end and travels right through the city to the east end, with 25 new stations and stops linking to 54 bus routes, three subway stations and various GO transit lines. That means shorter commutes, reliable and convenient transit and cleaner air.

But that kind of huge infrastructure project doesn’t come without more than its fair share of challenges! This was exactly the case at the Caledonia Station site. The ground conditions we encountered there were among the most challenging we’ve had to deal with in WJ’s long and successful involvement with the Eglinton project. However, we were confident that given our decades of experience and industry-leading practices, we were up for the challenge!

Eglinton Crosstown Caledonia Station dewatering

Multiple clay layers ran through the site, cutting up the aquifer into many different pieces. Factor in a massive 30m deep excavation, shored by soldier pile and lagging, and we had all the ingredients for a dewatering nightmare.

After coming in to rescue project developers, CTS, from an inferior dewatering system that couldn’t tackle these site conditions, WJ got to work with Crosslinx to uncover these layers. Our expert water management consultants deciphered the geology of ancient glacial lake bottom deposits that lay buried deep underground across Toronto.

However, in the world of dewatering, clay is clay. No matter how thin, a continuous layer can quickly change dewatering requirements.

Our deductions were proved correct when we uncovered a 1-inch thick layer of clay across the entire site. Working tireless to dewater each and every layer, WJ battled the water towards the base of the sump pit. From there. our sump pit dewatering actions provided a site suitable for CTS to complete their excavation and commence construction of the station from the bottom-up.

“WJ helped the Caledonia team through some very challenging conditions at Caledonia. They were committed and worked with us every step of the way. WJ’s can-do attitude was refreshing and much appreciated on this difficult and challenging site.”

– Daniel Sanchez, Project Manager, Caledonia and Keelesdale Stations.

LOCATION: Oakwood Station, Eglinton Crosstown Light Rail Transit
CLIENT: Crosslinx Transit Solutions
MAIN CONTRACTOR: CTS

Cross Cut Completion at Oakwood Station

WJ Group Admin July 18, 2019

The Eglinton Crosstown Light Rail Transit (ECLRT) project consists of 19.7 km of light rail transit running along Eglinton Avenue from Mount Dennis in the west to Kennedy in the east. The project is being designed and constructed by Crosslinx Transit Solutions (CTS).

With such an important and flagship infrastructure project, under constant public scrutiny, given the build disruption to local communities, the stakes were high. CTS needed a true water management partner who would work with them right through to the end. And that’s where WJ came in.

WJ was called in from the UK to take a look at dewatering requirements of the Eglinton Crosstown Project – a challenging commission, which combines difficult dewatering conditions with innovative construction techniques. Several of the stations within the Eglinton project are being constructed using a unique soil mining technique, known as the New Austrian Tunnelling Method. This meant that our dewatering solutions had to be just as innovative in order to succeed.

Right from the start, the Oakwood main entrance access (called the cross-cut) was flagged as the most challenging aspect of the project. A silty, low-permeability soil matrix that fines towards the bottom of the excavation was located just above a clay interface. Using, wellpoints, eductors, and deep wells, installed from the road surface and from confined spaces in TBM tunnels and mined caverns, WJ was able to complete this substantial dewatering feat, without any delay to the CTS mining schedule.

As everyone in mining knows: the mining can never stop!

WJ ensured it never did.

LOCATION: Oakwood Station, Eglinton Crosstown Light Rail Transit
CLIENT: Crosslinx Transit Solutions
MAIN CONTRACTOR: CTS

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.

Cambridge WWTW

WJ Group Admin August 24, 2015

As part of the renewal and upgrade of Cambridge’s WWTW works, WJ were called in to efficiently lower the groundwater level. A challenge which we more than rose to.

University College London

WJ Group Admin August 24, 2015

Recognised as one of the leading multidisciplinary research universities in the world, UCL was founded in 1826 as London’s first university.