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Secant Piling

DAWSON-WAM is a leading specialist in the design and installation of secant piled retaining walls for basements and deep excavations. Secant piles are formed by a sequence of interlocking bored concrete piles, creating a strong, continuous retaining structure. This method is particularly effective in poor ground conditions and sites with a high water table, where alternative systems may not be suitable.

Market-Leading Cased CFA Capability

Our in-house teams and specialist partners offer expertise across all aspects of industrial building construction, including:

  • Foundation design and construction for heavy-duty and specialist load requirements
  • Formwork, precast, and reinforced concrete works for structural durability
  • Steel fabrication and erection for industrial frameworks and portal buildings
  • Brickwork, cladding, and façade systems for both function and aesthetics
  • Mechanical and electrical installation to meet operational demands
  • Cranes, hoists, and access systems for manufacturing and logistics operations
  • Industrial doors, windows, and finishing works
  • Sustainability and energy conservation solutions to meet modern environmental standards
  • Landscaping and external civil works for site completion

This system is particularly well-suited for secant wall construction in sensitive environments, offering low-noise, vibration-free installation ideal for city centres and constrained sites.

Secant Wall Options with Our Cased CFA System

We offer multiple secant wall configurations to suit different project needs:

  • HARD/HARD Secant Walls – Both primary and secondary piles are constructed from structural-grade reinforced concrete
  • HARD/FIRM & HARD/SOFT Secant Walls – Primary piles use a lower-grade concrete while secondary piles are structural grade

Advantages

While all types have their applications, DAWSON-WAM specialises in HARD/HARD secant walls, which provide significant advantages:

Maximum strength and stiffness

  • All piles are structural concrete, and both primary and secondary piles can be reinforced

Superior water retention

  • Enhanced bond between piles improves watertight performance

Efficient load distribution

  • Axial loads can be spread through the piles, reducing capping beam requirements

Optimised pile spacing

  • Greater vertical accuracy and concrete strength allow for fewer piles, lowering cost and installation time

Challenges

Overcoming Ground Challenges & Obstructions

Using our Cased CFA (Continuous Flight Auger) piling system, we can negate flighting risk and maintain precise bore stability, even in variable or difficult ground conditions. Our equipment is capable of boring through:

  • Natural obstructions
  • Mass concrete and brick structures
  • Medium strong rock (<50MPa)

This capability allows us to maintain programme certainty and minimise the risk of delays when unforeseen ground conditions are encountered.

Low-Noise, Vibration-Free Installation

Our relatively silent and vibration-free piling techniques make secant piled walls ideal for use near existing buildings, roads, and sensitive structures. For tight urban environments, we can also deliver virtually zero-tolerance secant pile installation, maximising usable space without compromising safety or quality.

Applications in Basements & Underground Construction

Secant walls can form a continuous watertight barrier, making them an excellent choice for basement construction and underground car parks. DAWSON-WAM offers complete basement and foundation packages, including:

  • Piling design and setting out
  • Circumference piling
  • Capping beams
  • Bulk excavation
  • Temporary load anchoring and propping
  • Foundation piling, pile caps, and reinforced concrete works
  • Structural steel installation from basement to ground level

 

We also provide full pile testing, along with vibration and noise monitoring, ensuring compliance with industry standards and local environmental requirements.

Get in touch with our team