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

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