WJ News

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

Mixed-Use-6.png

Mixed Use Commercial & Residential Redevelopment Project

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.

UOIT multilevel excavation
New UOIT development

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
WJ dewatering in Oshawa
read more
Dan CarpenterMixed Use Commercial & Residential Redevelopment Project
Condos-1.jpg

Emergency Residential Condo & Commercial Development Dewatering

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.

UOIT multilevel excavation
New UOIT development

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.

WJ dewatering in Oshawa
read more
Dan CarpenterEmergency Residential Condo & Commercial Development Dewatering
Dewatering-for-Sump-Installation-5-1.png

Dewatering for Sump Installation

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.

UOIT multilevel excavation
New UOIT development

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.

WJ wellpoint installation at UOIT September 2019
WJ dewatering in Oshawa
read more
Dan CarpenterDewatering for Sump Installation
WJ-Eductors-at-Richmond-Condos.jpg

Eductor wells 543 Richmond Condominiums

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.

UOIT multilevel excavation
New UOIT development

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.

“543 Richmond Condominiums will always be special to WJ as our first residential dewatering project in the country.”

WJ wellpoint installation at UOIT September 2019
WJ dewatering in Oshawa
read more
WJ Group AdminEductor wells 543 Richmond Condominiums
WJ-Baby-Giraffe-Drilling-Rig-at-UOIT.jpg

Wellpoints at UOIT, Oshawa

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.

UOIT multilevel excavation
New UOIT development
WJ’s Baby Giraffe drilling rig installing wells around the perimeter of the UOIT excavation

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.

WJ wellpoint installation at UOIT September 2019
WJ dewatering in Oshawa
UOIT Oshawa New Block August 2020

“We were able to able to avoid having to install an energy inefficient and space hungry eductor system, saving our client $1,000s”

read more
WJ Group AdminWellpoints at UOIT, Oshawa