PILE FAILURE has halted construction on part of the high pro Greenwich Millennium Village project in East London.
Structural engineers are now on site investigating the failure which has 'come out of the blue' said a spokesman for client GMV, a joint venture between Taylor Woodrow and Countryside Properties.
Work on installation of pile caps was stopped last week when the 10.3m to 11m long, 450mm diameter reinforced in situ concrete piles began to fail during testing. An 8t static load test caused excessive settlement of about 50mm, explained one site worker.
A spokesman for GMV said that although at least four piles have been identified as failing, 'one of the piles passed with flying colours'.
Design and build piling contractors Laing O'Rourke and Cementation Foundations Skanska are carrying out further load tests on the piles as well as additional site investigations, said a site worker. 'If they [the piles] sink', he added, 'they have to pull them out and replace them with deeper ones - something more like 60ft (18m).' If all the piles have to be replaced it could cost in the region of £1M, said experts. The piles were being installed for a multi-story, eco-friendly apartment block designed by Erskine Tovatt Architects and Planners.
A piling expert said it was likely the piles were founded on the Lambeth Group, a mix of clays, sand, silt and gravel. The formation is also notorious for the random appearance of peat or limestone patches, he said.
The GMV spokesman said ground conditions were well understood as the entire area was remediated in 1990 by English Partnerships, when contaminated land from the former gas works site was removed. He added that the piles extended beneath the capping layer of remediated ground to the strata below.
Apartment blocks built on the site over the past seven years are not exhibiting any signs of subsidence.
Ground work is expected to be completed in 7 - 8 months.
Laing O'Rouke and Cementation Skanska declined to comment.