Case Study: CFA Piling and Groundworks for Luxury New Build

Location: 5 Park Avenue, Radlett

Project Scope: Piling, drainage, and groundworks for a luxury residential new build

Ground Conditions: All clay

Timeline: 10 Weeks (Completed 2 weeks ahead of the 12-week schedule)

Background

This project required the installation of a foundation system and comprehensive groundworks for a new luxury residential build. The site had been previously demolished and cleared by a separate contractor prior to our arrival. Operations were conducted with strict consideration for the surrounding high-end residential neighborhood to minimize local disruption.

Site Context & Logistical Blockers

The site presented specific environmental constraints that dictated the engineering approach rather than standard logistical blockers:

Tree Root Preservation Area: Proximity to protected trees necessitated a piled foundation solution to bridge the root zones without causing damage.

Adjacent Watercourse: The site was located in close proximity to a local brook. This required stringent adherence to Risk Assessments and Method Statements (RAMS) to prevent any operational runoff or environmental impact during heavy works.

The Fallon Piling Solution

Site Preparation: Installation of a certified piling mat prior to rig deployment to ensure stability and safe operation.

Methodology: Continuous Flight Auger (CFA) piling was utilized to securely bore through the clay stratum.

Specifications: Installation of 300mm diameter CFA piles, bored up to a depth of 15 meters.

Machinery: A 20-ton Hutte rig was deployed to execute the deep boring required for this specification.

The Result

The project concluded in 10 weeks—two weeks ahead of the projected 12-week timeline. Following the successful installation of the piling mat and the 15m deep CFA piles, the team completed all subsequent groundworks and the new underground drainage system.

Following the drainage phase, the structural raft slab was constructed. Due to the site's sloping terrain, the engineering required the raft to be constructed with deep down-stands at the rear to effectively manage the gradient.

Once the concrete works for the raft slab were complete, MOT Type 1 sub-base was installed around the site perimeter. This provided a secure and stable scaffold base, ensuring the site was fully prepped for the follow-on trades. Strict compliance with the site-specific RAMS successfully mitigated all risks associated with the nearby brook throughout the process. The completed foundation system was handed over on an accelerated timeline, ready for the above-ground construction phase.

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