Not so long ago Southwark was a forgotten and largely overlooked pocket of inner London. Despite its river frontage and proximity to the City, the area remained run-down. But that was before the Jubilee Line extension, Tate Modern and Millennium Bridge provided the catalyst to transform Bankside, as Southwark’s river frontage is known, into one of London’s most chi-chi locations.
And now the regeneration is spreading back from the Thames, most notably the redevelopment of Bankside 123, a major office-led development of three buildings immediately south of the formidable Tate Modern.
Developer Land Securities is behind the scheme to replace the run-down early 1960s-built PSA offices on Southwark Street. Early focus has been on demolition and enabling works for Building 1, which will become the new headquarters for publisher IPC.
Unusually foundation engineering has been a major component to the enabling works. This explains Mohsen Vaziri, director with structural engineer Whitby Bird, is because the biggest constraint on site was the forest of existing piles, installed to support the 13 storey PSA buildings and its two-level diaphragm wall-supported basement.
The previous structures were founded on 450mm diameter driven Frankipiles, up to 15m long and based in the river gravel deposits. These were evidently adequate for purpose through the forty-year life of the previous structures; but although Whitby Bird looked into making use of these existing foundations, they were simply not up to modern design standards.
The only real option was to design the new scheme with relatively few, very high capacity piles and to remove the existing foundations where they clashed with the new.