Currie Reservoir – Continuous Caisson Wall

Increased Safety: We Used Horizontal H-Piles

This project is a part of a large upgrade to the Currie Reservoir in southwest Calgary, Alberta. The project included the installation of a caisson wall as well as horizontal shoring and underpinning.

The purpose of the installation of the caisson wall was to provide support for the existing pump-house structure as the excavation was taking place between the pump-house and underground water tank.
The retaining wall was designed by J.R. Spronken & Associates Ltd. as a Cantilever Secant Pile Wall with a maximum excavation depth of 8.0m below grade.
The length of the shoring wall is approximately 48 linear meters with total exposed surface area of about 370 square meters.
The pile sizes used include 760mm soldier piles and 610mm filler piles. The overall scope of the work consisted of drilling 28 soldier piles and 30 filler piles.

The client also approached HCM with the request to provide horizontal shoring/underpinning at the bottom of the excavation in order to provide a safe working platform for the connection of a 900mm diameter pipe between the pump-house and water tank. HCM completed this task by pushing a series of H-piles horizontally, using a hydraulic jack which was set-up on a specially designed steel frame system attached to the caisson wall.

HCM Contractors completed this project ahead of schedule and to the complete satisfaction of both the client and the engineer.

Client: PCL Construction Management
Location: Calgary, Alberta

Currie Reservoir

Horizontal Underpinning

This project consisted of an interlocking secant pile wall, combined with horizontal underpinning to accommodate a new connection to a pump house at the Currie reservoir in Calgary. The interlocking secant pile wall (caisson wall) allows for an accelerated construction schedule as it eliminates the ground loss that is present with the use of other styles of shoring. Where utilities were present, bracing supports were used to resist the lateral pressures present behind the filler piles.

Unique to this job was the installation of horizontal underpinning. The job required a new connection between the existing reservoir and pump house. To accomplish this task, a tunnel had to be created to accommodate the 900mm connecting water pipe. The underpinning provides support for the tunnel walls. The system worked well; after excavation, the resulting tunnel allowed safe access for the installation of the connection pipe to the pump house.

Because of the job’s proximity to the working water reservoir, special environmental precautions had to be taken in order to avoid contamination. Site-specific procedures were implemented; in instances where lubricating oils had to be used, for example when sliding the horizontal underpinning beams, food grade oils were used over hydrocarbon-based oils. As a result, the integrity of the water supply was maintained throughout the duration of the project.

Client: PCL
Location: Calgary, Alberta

Graham Residence

Residential Shoring: Complex Design Requires Innovation

A retaining wall was required to accommodate the architectural design for a private residence. The site topography presented the General Contractor (Builder) with the challenging task of constructing a retaining wall structure into a steep hill on a residential lot in the Mount Royal area of Calgary, Alberta. To accommodate the residence, extensive shoring was required along the property lines and the back alley of the site.

The retaining wall was designed by T.H. O’Rourke Structural Consultants Inc. as a Tied-back Shotcrete Shoring Wall with its excavation depths ranging from between 6.0m to 12.0m below-grade.
The length of the shoring wall is approximately 87.0 lin. metres with a total of 382 square metres of exposed surface area. The shoring design also reflects the structural Engineer’s requirement for a permanent retaining wall at the back of the property (deepest excavation).
In addition, the client accepted HCM’s proposal to provide monitoring of the permanent wall, which included the supply and installation of inclinometers and their subsequent reading for the duration of one year.
HCM completed the soil nailing operations with a TEI drill mounted on an excavator hoe.
The project required precision in placing the shotcrete shoring along the contour of the building envelope as a significant amount of the shoring was adjacent to the property’s steep slope.
Also, special emphasis was put on the sensitivity of the entire project with respect to neighboring properties, minimizing disruption, noise and vibrations to existing structures.

HCM Contractors finished this project on schedule and to the complete satisfaction of the Builder and Owner.

Client: Wiens and Company
Location: Calgary, Alberta

CN Malton GO Station

Challenge: Build While Trains Are Running

Work on the Malton GO Station in Toronto, Ontario includes improvements such as new walkways and a tunnel for pedestrian access to new platforms.

HC Matcon’s scope of work, includes:

37 caissons at 30-inch diameter, and an approximately 25-foot deep shoring system with strand anchors.
The pile and caisson installation was challenging due to a number of factors. The train tracks, in close proximity to the work being done, were required to be fully operational.
Special precautions were taken for track protection and the safety of workers.
Due to the close proximity to Pearson International Airport, special precautions were taken to conform to the Greater Toronto Airport Authority’s guidelines for the operation of high-mast drills and cranes.
HC Matcon accommodated special staging requirements set forth by CN for work, such as the installation of the precast tunnel and track relocations.

HC Matcon will work with all parties involved in a project to ensure a swift execution with minimal conflicts.

Client: B. Gottardo
Location: Toronto, Ontario

St. Joseph’s Healthcare Redevelopment Project

Unique Soil Conditions

The future location for this tower is located immediately adjacent to the emergency wing of the existing St. Joseph’s hospital in Hamilton, Ontario. HCM is a recognized shoring contractor that will take on many challenges relating to foundation design.

On this particular project, HCM took on the tasks of:

shotcrete shoring
caissons
micropiles
excavation
site services
demolition with the constraints of limited access and project complexity.

A portion of the work was to be performed indoors, which required special care towards the patients of the hospital and the HCM workers. The original design for this inside work included conventional pad footings dowelled in to existing caissons five feet below the finished floor. The soil conditions are unique on this project due to the fact that the site is situated at the bottom of the Niagara Escarpment where bedrock is on an incline. This increased the depth required for adequate bearing stratum, requiring the entire area to be excavated and the perimeter shored. To save costs to all parties involved, HCM proposed an alternate to the original design to provide hand-dug caisson caps around the existing caisson and column construction. Caissons were excavated to depths of 18 feet below the finished floor using reinforced compression rings and shotcrete shoring to reach adequate bedrock.

The above innovations were the optimal solution for this portion of work resulting in another successful hospital project by HCM on budget, on time.

Client: PCL
Location: Hamilton, Ontario

TTC Wilson Complex Modification

Engineering Solutions

The Toronto Transit Commission will be purchasing all new subway cars in the near future, creating the requirement of larger maintenance carhouses. The original contract drawings employed caisson wall, soldier piles and lagging, and conventional concrete underpinning for the earthwork specifications related to our field of work. HC Matcon proposed an alternative engineered solution that included the use of shotcrete, underpinning, micropiles, soldier piles and shotcrete lagging (SPSL) to achieve the same effect. The acceptance of this proposal allowed for a substantial cost savings to the owner, as well as a shorter construction schedule for the various contractors involved. Mechanical jacking pits were built where shoring is used as a backform for manholes. Shoring for carhouses below- grade will be used as a backform for foundation walls. The substitution of shotcrete underpinning in lieu of caisson walls will allow for easier access to the tunnel portion of the project. This will allow for less demolition of the existing building and less clearance issues.

The above are just a couple examples of the innovations that HCM Contractors Inc. will use to add value to any project.

Client: Aquicon Construction
Location: Toronto, Ontario

Credit Valley Hospital

Alternative to Save Time and Money

The Credit Valley Hospital in Mississauga, Ontario is undergoing a massive expansion and renovation. HC Matcon was brought in to undertake the shoring, underpinning, and caissons for this construction. The majority of the work included the drilling and installation of 222 concrete caissons, ranging between 24- and 84-inches in diameter. The original design required concrete-encased steel beams and conventional timber-lagged shoring adjacent to the operating hospital for support of the existing building and excavation. HC Matcon proposed an alternate to use vertical micropiles and shotcrete shoring in lieu of the above, which resulted in less disruption to the functioning hospital. The acceptance of this proposal also allowed a savings in cost and schedule time for the general contractor and owner. HC Matcon is able to overcome challenges while working with all parties involved to add value and cost savings to a project.

Client: Bondfield Construction
Location: Mississauga, Ontario

EEEL University of Calgary

Zero Ground Loss

This project followed shortly after finishing the Taylor Family Digital Library project, which was in close proximity to this site on the same campus. Design considerations for the foundations were almost identical to the previous project, with the installation of approximately 175 cast-in-place belled piles. Again, this new building was a result of the fast-growing population at the University of Calgary and the demand for specialty studies with emphasis on future global trends such as clean energy and the environment.

The soil conditions, which are typical and uniform throughout the mentioned site, consisted mainly of silty sand and clay till which is ideal for large capacity belled piles.

The shafts for the piles were predominantly 900mm, 1000mm, and 1,200mm in diameter.
The bells were sized at: 2000mm, 2400mm, 2800mm, 3400mm and 3600mm in diameter.

The average founding depth on this project was approximately 13.0m – 17.0m with the need to protect the upper portion of the pile shafts by using temporary casing approximately 8.0m long. The concrete volumes for single piles ranged between 23 – 26 cubic meters. Among the challenges for HCM on this project was installation of piles in close proximity to a concrete utility tunnel. EllisDon approached HCM with a request for shoring and underpinning on a portion of the tunnel.

HCM proposed a design/build tied-back continuous caisson wall method where special consideration was given to the stated goal of zero ground loss from underneath of the tunnel.

Client: EllisDon Corporation
Location: Calgary, Alberta