WJ News

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

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Sump Pit Completion at Caledonia Station

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
Eglinton Crosstown Caledonia Station dewatering
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.

Eglinton Crosstown Caledonia Station dewatering
Eglinton Crosstown Caledonia Station dewatering
Eglinton Crosstown Caledonia Station dewatering

“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.

Eglinton Crosstown Caledonia Station dewatering
Eglinton Crosstown Caledonia Station dewatering
Eglinton Crosstown Caledonia Station dewatering
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WJ Group AdminSump Pit Completion at Caledonia Station
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Quick Turnaround Dewatering at Science Centre Station

Being the largest transit expansion in Canada, with significant on-going disruption to Toronto’s population, any delay to the development of Eglinton Crosstown LRT is not welcome news. Especially when that delay is totally unexpected. That’s exactly what happened when the construction crew discovered groundwater where there wasn’t supposed to be any!

Early one morning, WJ Canada received a call for help. The CTS construction team, working at the Science Centre Station, encountered groundwater at the bottom of the excavation. The Science Centre Station is the longest excavation on the entire Eglinton Crosstown project, at 800m in length, with the deepest part being underneath Don Mills Road.

dewatering at Science Centre Station
dewatering at Science Centre Station
dewatering at Science Centre Station

According to a previous hydrogeological investigation, there was not supposed to be water present. Yet, to their surprise, as the CTS crew approached the bottom of an aquifer on a clay Till, they were greeted by approximately 1m of water. This prevented the last section of excavation and concrete placement. It also meant a potentially serious delay to the project!

Once we’d received CTS’s call for help, WJ was on-site within just a few days and we wasted no time in getting straight to work. This involved drilling inclined well-points on both the north and south side of the excavation. We worked from the bottom of the shaft, through the lagging wall, and got the entire system commissioned in record time.

dewatering at Science Centre Station
dewatering at Science Centre Station
dewatering at Science Centre Station

Just two weeks after receiving their call for help, WJ had dewatered the Science Centre Station site. CTS were able to resume excavation in dry conditions. Within 3 months, CTS had completed all concrete and waterproofing systems and WJ was able to decommission the system.

“WJ came in on very short notice and executed a professional and effective dewatering solution. Their solution was cost effective and efficient as the wells were short and installed from the base of the excavation. The solution was tailored to our needs as they allowed us to complete our station build-back all the while remaining functional behind the waterproofing membrane. I would recommend WJ to any contractor in need of a dewatering partner.”

– Diego Ocampo, Project Manager, Science Centre Station

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WJ Group AdminQuick Turnaround Dewatering at Science Centre Station
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Cross Cut Completion at Oakwood Station

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, ejectors, and deep wells, 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.

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WJ Group AdminCross Cut Completion at Oakwood Station
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The Royal Parks

‘The Royal Parks’ are an essential government-funded organisation that manages the conservation of the eight major parks in London as well as other smaller areas of garden and parkland.

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WJ Group AdminThe Royal Parks
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Cambridge WWTW

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.

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WJ Group AdminCambridge WWTW
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University College London

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

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WJ Group AdminUniversity College London
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Crossrail Underground Station at Farringdon

One of several Crossrail projects entrusted to WJ Groundwater, Farringdon Station sits at the heart of London’s transport system and will provide access to three rail networks: Crossrail, London Underground and Network Rail.

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WJ Group AdminCrossrail Underground Station at Farringdon