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Van Elle of a muddy job

PILING

Furlong Homes is beginning a two-year programme to build a mixed use development with 250 luxury apartments on the banks of the river Roding in Barking. Paul Thompson went to see how geotechnical contractor Van Elle is helping get the scheme off the ground

IT IS 10:30 am on a Monday morning in Barking, East London and Simon Shuker, southern area business development manager for geotechnical contractor Van Elle, is looking nervous.

Not that he is troubled by the work going on at the Abbey Road site for developer Furlong Homes. His furrowed brow is thanks to this being the decisive final day of the final Ashes Test. All is about to unfold just a few miles across London at the Oval in Kennington.

'It has been an incredibly excit ing Ashes ser ies, ' he says, 'I just hope England can see it through to the end.' In professional terms the end is almost nigh on this particular project for Mr Shuker and Van Elle project manager Ian Jones. There is probably another week or so left to tie up all the loose ends on a £600,000 scheme which will have seen the site team bore 1,275 continuous f light auger bearing piles across the compact site.

Some of the 400 mm and 500 mm diameter piles are as deep as 19 m because of the ground condit ions at the site which sits on the north bank of the river Roding.

Part of the development will be built upon the river's reclaimed f lood plain around the site and the underlying ground conditions ref lect the chequered history of this part of east London.

'Across most of the site there is made ground for a couple of met res then you are in to London Clay, ' says Mr Shuker.

This is the underlying material on which the CFA piles will bear but there are issues with the initial material, says Mr Jones.

'London Clay is very good mater ial and in its virgin state is bluish in colour. But the first few metres of it are brown and weathered so we have to get through this weathered zone and into the blue stuff, ' he says.

The final 500 mm diameter piles will carry a maximum load of 1,275 kN with the 400 mm diameter carrying as much as 700 kN. Both diameters will dissipate the loads through skin friction and end bearing.

The eight-week contract period forced Van Elle to use two different rigs on the project, a Lamada P-130TT and a Soilmec CM-48. Both started at different ends of the tight site because of the quick changeovers needed to keep up to programme while boring mixed diameter piles in the same area.

'Both can do the same diameter piles and they have been pretty productive. Between them we have been averaging around 50 piles a day which is very good, ' says Mr Shuker.

The two have moved steadily through the project and are now working in close proximity to each other, a problem that will mean one of the r igs will be taken off-site before complet ion.

'We will have to pull one of the rigs off the scheme before we have completely f inished otherwise they will be work ing too closely to each other and there will be health and safety issues, ' says Mr Jones. 'You need to keep enough distance between the rigs for them to topple without colliding.' The two rigs are working in the southern corner of the site, an area plagued by the high water table. They are bursting through it after only a few metres. This means that no sooner has the client's engineer set out the position of the piles then the marks are obliterated by the rigs churning up the surface. The volume of wet mud coming out of the boreholes does not help either.

'We have had to keep a guy on-site permanently to set out the position of each pile as and when we need it. He has been very busy, ' says Mr Jones.

Two steel fixers are on site, frantically tying the 16 mm and 20 mm diameter rebar for the pile cages. They will be dropped into the boreholes and backfilled with a standard C30 mix concrete.

Despite the repetitive nature of the piles and the total number Van Elle decided against prefabricating the cages and bringing them in when needed.

'There is not really enough room to store hundreds of pile cages on this site. A lso the pract icalit ies of br inging in tonnes of prefabricated cages down from our head office in Nottinghamshire and through London meant it was a non-starter, ' says Mr Shuker. 'The two fixers work f rom site to site as and when they are needed.

We have a lot of work in London at the moment.' And with that Mr Shuker is off in his car to check up on another Van Elle site in the capital ? and likely listen to Kevin Pietersen's Ashes clinching innings for England.