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Mon February 17 2020

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Keltbray drills 78-metre piles at Nova East

10 Feb Keltbray Group is currently on site drilling what are believed to be some of the deepest piles ever bored in London.

Keltbray's Bauer BG36 rig at Nova East
Keltbray's Bauer BG36 rig at Nova East

The foundations of Land Securities’ Nova East development, next to London Victoria station, require piles of 1500mm and 2000mm diameter drilled to depths of 78 metres or more.

Keltbray started on site in October 2019 and began sinking the deep bearing piles in January. This is programmed to continue until April, with the substructure and basement dig following on.

Existing piles have been left in the ground from the previous building on site.  Some of these clash with new foundations so need to be removed.

The first element of piling works is the retaining wall piles being installed to create a basement for the new building. The new building is being founded on the secant wall rather than standard bearing piles because of all the London Underground tunnels below the site.

These retaining wall piles are to be installed towards the centre of the site.

Nova East has also seen the first ever pile formed using Wagners Earth Friendly Concrete (EFC) in London. EFC is a product manufactured by Australian firm Wagners and is a zero cement, geopolymer concrete supplied by Capital Concrete in London.

For the piling works, Keltbray is using a Bauer BG36 rig. The piles are cased to a maximum of 19 metres, using Bauer’s new Crowd Plus system.

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Sinking piles for a secant wall
Sinking piles for a secant wall

Warren Arnold, sales and service engineer at Bauer Equipment UK, asked on the LinkedIn social media platform whether anyone knew of any deeper piles in the capital. After some discussion, it was confirmed as a rare, if not unique, feat.

To a suggestion that The Shard’s foundations were deeper, Warren Armold replied: “Balfour Beatty Ground Engineering / Stent did the Shard with their old BG36, they never had a Kelly bar long enough either with that rig to drill past 70+ metres.”

However, one contributor to the LinkedIn conversation does claim to have gone deeper – and very close to the Nova East site.

Tony Amis, now senior vice president of GI Energy US, used to work for Cementation, which is now part of Skanska. “In the early 90s I worked on 173 Victoria St, opposite Little Ben clock,” he posted. “The building sits over the ox barn sewer and the pile on the corner was drilled by Cementation to 80 metres to cope with the tension loads. [It was] designed by the late Ken Vickery. We set up bentonite tanks just in case, they were needed, but we managed without. Bentley Works [Cementation’s in-house manufacturing facility in Doncaster] extended the traditional Kelly bar so we could get to the required depth.”

Keltbray on site in Victoria
Keltbray on site in Victoria

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