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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

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.

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.

Charisma Condos, Vaughan

Dan Carpenter April 25, 2021

Charisma Condos, Vaughan

Vaughan, home of Canada’s Wonderland, the largest amusement park in the country, is one of Canada’s fastest growing cities. It is this growth, and in particular the Charisma Condo project, that took us the short distance north from our Toronto HQ.

Multi-tower Condo Development

The Charisma Condo is a multi-tower development with numerous phases of deep excavations in to underlying water bearing soils. Due to the scale of the project and this aquifer, the client had initially considered putting in a full cut-off caisson wall, designed for hydrostatic loading. This would have eliminated the need for dewatering but at a cost of many millions of dollars.

Fixed-price dewatering guarantee

Early client engagement here was key. WJ were able to explain to the client that the previous groundwater problems they had experienced in the area could be eliminated with WJ’s dewatering techniques, which could offer significant overall cost savings for the project compared to the installed of a cut-off caisson wall. Convinced of our abilities and understanding of the conditions on site, we offered a fixed price guarantee on the performance of the dewatering system.

Project Cost Savings

Via the installation of our dewatering system the client was able to complete the excavations without either problematic groundwater or the expense of the cut-off caisson. This project demonstrate how working with WJ from an early stage on a project can save condo developers time and money, as well as reducing the overall project risk.

LOCATION: Vaughan, Ontario

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

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.

Lodz High Speed Rail Interchange, Poland

WJ Group Admin August 19, 2015

This highly exciting contract allowed WJ to branch into an entirely new area of expertise.