An innovative piling method using minidiggers in place of a single piling drill has been used at the site of new headquarters for blue chip bank NM Rothschild & Sons.

The smaller, lighter rigs are easier to move around the site and require less earthworks to accommodate onsite, unlike the large machines (typically weighing 70 tonnes) normally used.  The method has significantly de-risked the works and allowed the construction programme to be resequenced, with piling being brought forward and work on the building core beginning earlier than would have been possible otherwise.  It has also allowed the creation of a larger basement area, thanks to the ability of the minidiggers to drive in piles closer to the site boundary.  The piling has had to take into account both a Docklands Light Rail route and a 1.8m Thames Water sewer.

As far as development manager Stanhope is aware, this is the first time this method of piling has been used on this scale.

The site, which has housed Rothchild's London headquarters for the past 200 years, is located in St Swithins Lane in the City of London.  Surrounded by neighbouring buildings - including Grade I listed church St Stephens Walbrook - and serviced by an extremely narrow street, the constrained nature of the site has required careful consideration of logistics.  Stanhope and the team comprising Bovis Lend Lease and McGees have worked closely with neighbours to minimise the disruption to them, erecting an acoustic screen, installing double glazing on neighbouring premises and carrying out as much work as possible out of hours. 

Once piling is complete, scheduled for June, work constructing the Rem Koolhaas-designed building will begin, producing 140,000 sq ft net of high quality office space, an archive and research room for the Rothschild Archive, a roof garden and a Sky pavilion offering panoramic views across the City.

Bovis Lend Lease is the construction manager for the project and Arup are providing engineering services.  The building is scheduled for completion in late 2011.