Sheet piling and precast capping
Grand Union Canal, Wembley
Canal-side retaining works for DSM / St George in 2019–2020, combining permanent sheet piling with bespoke precast concrete capping beams.
The challenge
The retaining wall had to follow the canal alignment through variable ground, including made ground, alluvium and London Clay. Canal-bed levels, buried services and access constraints informed both the permanent design and the construction sequence.
Our role
The scheme was delivered through Ale Piling, now part of the DAACE operation. It brought together steel sheet piling and precast reinforced-concrete capping. The project record includes a permanent works design report (WO1131.01, July 2019) covering the ground model, wall sections, loading, corrosion allowance and a design risk register.
Design and method
The piling method specified 444 piles, with lengths of 6.5–9m in the permanent design and a 100-year design life for the permanent wall. The planned installation combined a MOVAX side-grip piling system with impact driving where required. Survey information and as-built pile layouts fed into capping-beam fabrication drawings, and standard and bespoke units, tapered ends and expansion joints allowed the capping to follow changes in direction, reducing the need for canal-side shuttering.
Safety and site interfaces
The capping method specified a secured floating platform with edge protection, lifejackets, lifebuoys, emergency ladder access and a second banksman. Crane and excavator lifts were supported by a prepared, plate-tested working platform and controlled lifting areas. Design correspondence addressed buried high-voltage services, and the piling method proposed vibration monitoring with a defined trigger to stop and review operations. The sequence addressed silt control, temporary water exclusion and puddling-clay reinstatement, with hot-work permits, fire precautions and exclusion zones.
Outcome
The brochure shows the completed canal-side sheet pile wall and concrete capping from the company project archive. The safety measures described are the documented project requirements from the methods and design records.
