Installation of a sloped staircase on helical piles

Type of Project 

Installation of a sloped staircase on helical piles to support a wooden structure. 

Location 

Sentier des Grèves, Quebec, Canada 

Challenges 

The City of Quebec wanted to create a connection between the St. Lawrence River shoreline (Samuel-de-Champlain Promenade) and the top of the hill near the bridges, completing the Sentier des Grèves trail.
The steep slope (40 degrees) and the ground made up of fill with rock fragments and sandy gravel made the installation complex. The project needed to minimise environmental impact and noise, meet strict deadlines, and ensure the stability of the wooden structure. 

This 1.7 km pedestrian path runs along the river between Jacques-Cartier Beach Park and the Pierre-Laporte Bridge. It offers direct access to Gagnon Beach while revealing exceptional views of the river and nearby infrastructure. 

Designed with the greatest respect for a sensitive natural environment, the trail includes interpretation panels that enhance visitors’ experience by explaining the tidal phenomena and landscape evolution. 

Solutions 

A year before the start of the works, WSP engineers consulted Techno Pieux to assess the project’s feasibility and explore the use of helical piles as a foundation solution. Other methods considered presented significant technical challenges due to the demanding site conditions. 

After a detailed analysis, the team confirmed that installing helical piles was not only feasible but also the most suitable solution, even under such extreme conditions. Detailed plans and specifications were then developed, making the project possible through this innovative technology. 

To meet these challenges, 36 P5-type piles were installed using R2D equipment, with a torque capacity of around ± 3,300 lb-ft and an average depth of 8'-11". Each pile was precisely positioned to support the braced wooden structure. This approach enabled a quick installation with compact equipment, no excavation, and a lower cost than traditional methods.
Three people worked on site (one installer, one welder, and one general assistant), and the entire job was completed in five days. 

Results / Conclusion 

The installation of helical piles made it possible to create a safe, functional staircase for visitors while preserving the site’s sensitive environment. The method ensured quick execution, optimal stability, and minimal impact on the slope.
Completed in 2015, this project finalised the Sentier des Grèves, providing privileged access to the Samuel-de-Champlain Promenade, Gagnon Beach, and stunning views of the St. Lawrence River. 

Additional Information 

Dealer: TP Québec Est
Client: Les Constructions Bé-Con Inc.
General Contractor: Les Constructions Bé-Con Inc.
Load capacity: 25 kN (service) per pile 

External link: 

Techno-Metal-Post-Sentier-des-greves.pdf