Project: Boundary wall support for stormwater installation
Location: Marrickville, NSW
Sector: Civil / stormwater infrastructure
Client: Trescon
Services Provided: Temporary works engineering, equipment hire, installation
Equipment Used: Legend 50T Modular Propping System, tilt prop bracing, concrete block counterweights
Project Overview
Contractor Trescon needed to excavate adjacent to a neighbouring property’s boundary wall in Marrickville to install a new stormwater line. Removing soil from the front face of the wall would leave it laterally unsupported and at risk of failure.
Legend Hire engineered a temporary propping system using the Legend 50T Modular Propping System, with tilt-prop braces transferring lateral load back to concrete block counterweights. The system stabilised the wall without relying on the ground being excavated, giving Trescon safe, unobstructed access to complete the works.
The Challenge
The new stormwater line ran directly along the base of an existing boundary wall. Excavating in front of the wall would remove the passive soil support holding it upright, creating a lateral stability risk to a neighbouring asset. Conventional ground anchors weren’t viable as the excavation zone was the very ground that would otherwise resist the props. Trescon also needed the support system kept clear of the trench line to maintain working access.
The Solution
Legend Hire engineered a raking propping arrangement using the Legend 50T Modular Propping System. Vertical posts were fixed against the wall face to spread load across the structure, with tilt props installed as inclined raking braces.
Rather than founding the props on the soil to be excavated, the braces were tied back to concrete block counterweights, so lateral thrust from the wall was resisted by the dead weight of the concrete blocks. This kept the support independent of the excavation and clear of the trench, preserving access for Trescon’s crews.
Equipment Used
- Legend 50T Modular Propping System (vertical posts and connection components)
- Tilt props configured as raking propping
- Concrete block counterweights as reaction foundations
The Outcome
The boundary wall was held in a stable, fully supported state throughout the works, with lateral loads safely managed and no reliance on ground anchors or trench-line obstruction. This gave Trescon safe, unobstructed access to complete the excavation and stormwater installation, protecting the neighbouring property with zero incidents.
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Frequently Asked Questions
Boundary wall propping is a temporary works system that laterally supports an existing wall while adjacent excavation removes the ground that would otherwise hold it in place.
When excavation occurs in front of the wall, the ground can’t be relied on to resist the props, so raking braces are tied back to concrete counterweights blocks that provide the reaction load independently.
A modular propping system spreads load across the wall face, and raking tilt props transfer lateral thrust into a stable foundation clear of the trench.