Dewatering and Groundwater Control Archives - Page 2 of 4

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

Quick Turnaround Dewatering at Science Centre Station

WJ Group Admin July 18, 2019

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.

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.

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

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

Eglinton Crosstown Light Rail Transit System

WJ Group Admin July 16, 2018

The Eglinton Crosstown Light Rail Transit (ECLRT) project

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.

Ipswich Tidal Barrier

Dan Carpenter July 19, 2017

This contract took us to the heart of Suffolk, to aid with the construction of a new Tidal Barrier Gate for the River Orwell, to reduce the risk and impact of flooding to the coastal town of Ipswich.

Brighton I360

WJ Group Admin August 24, 2015

In 2000, when the London Eye opened to huge critical acclaim and quickly became the UK’s most visited paid-for visitor attraction, countless cities wanted an ‘Eye’ of their own but found that a similar wheel design would not be financially viable without a suitable site or sufficient guaranteed visitor numbers.

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.