50 Fenchurch Street

Keltbray was appointed to deliver a comprehensive package of demolition, ground engineering, excavation and substructure works for the redevelopment of 50 Fenchurch Street, a major commercial development in the heart of the City of London. The project occupies a highly constrained island site incorporating the Grade I listed All Hallows Staining Church Tower and the Grade II listed Lambe's Chapel Crypt, requiring a carefully engineered approach to excavation and ground movement management. 

Ground engineering played a critical role in enabling the redevelopment. The works included the installation of a 1,200mm diameter secant piled wall around the site perimeter, plunge column piles adjacent to the retained church tower and the excavation of approximately 81,000m³ of material to create a 17-metre-deep basement. Extensive modelling, monitoring and temporary works design were employed to manage settlement, heave and vibration throughout the excavation process, ensuring the protection of surrounding structures and sensitive heritage assets. 

One of the project's most significant engineering challenges was facilitating deep excavation beneath and around the historic church tower while maintaining its structural integrity. Keltbray developed a complex temporary and permanent works solution incorporating underpinning, plunge column piles, temporary propping and a new raft foundation system. Working within a dense urban environment, the project also required careful management of utilities, archaeological discoveries, neighbouring properties and constrained logistics, demonstrating Keltbray's expertise in delivering complex ground engineering solutions in challenging city-centre locations. 

Before redevelopment, the site comprised multiple existing structures, historic assets and complex below-ground constraints; afterwards, Keltbray had created a secure and stable excavation, installed the permanent ground-retention systems and prepared the development platform for construction of the new commercial scheme. 

Key Facts 

• 81,000m³ bulk excavation undertaken to create a 17-metre-deep basement. 
• 1,200mm diameter secant piled wall constructed around the site perimeter. 
• 26 reinforced concrete underpins installed to support the retained Grade I listed church tower. 

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