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Forcasting the good times

Spotlight - Geotechnics

The geotechnics sector can be seen as a barometer for civil engineering and construction as a whole, as Margo Cole reports.

When a construction sector is booming, it will always be heralded by an increase in work for geotechnical consultants and testing specialists.

At the moment, with many areas of the industry faring well, there is plenty of geotechnical work around. A slight downturn in new commercial building is more than offset by commissions to investigate the foundations of existing structures destined for conversion.

And infrastructure work is also booming. 'We are very busy on both road and rail projects, ' confirms Steve Hodgetts, a geotechnical specialist with consultant Scott Wilson. 'We have been flat out for the past five years - particularly on the rail side.'

The firm has won work through the Highways Agency's early contractor involvement (ECI) process, which Hodgetts believes gives more scope for site investigation than design and build, which it replaces.

'It's probably a more comfortable process from our point of view, ' he says.

'With design and build you've got to work with what you're given, with the possibility to do a little bit of investigation at the tender stage or when you get possession of the site. With ECI there is more scope and we can schedule more time for the geotechnical investigation.'

However, he adds, there are fewer opportunities for site investigation with ECI than there would have been with traditional procurement.

Scott Wilson is working with contractor Alfred McAlpine on one of the Agency's first ECI schemes, the A30 Bodmin to Indian Queens Bypass in Cornwall.

As client's agent for the scheme, Mouchel Parkman commissioned the site investigation. It included cable percussion boreholes, some with rotary follow on, as well as geophysical surveys to locate possible mining problems.

The company does a lot of geotechnical interpretation for local authorities in the southwest, including a partnership agreement to provide geotechnical support to Cornwall County Council and a term contract with Wiltshire County Council. 'That could involve anything to do with highways, ' explains Mouchel Parkman senior assistant geotechnical engineer Tony Daly. 'It is for all work on country road schemes, so could include remedial works, land slips or new improvements.'

Away from the infrastructure sector, one boom area is geotechnical investigation for structural engineers redesigning and remodelling existing office buildings.

Lankelma CPT, which specialises in geotechnical and environmental in-situ investigation using the static cone penetration method, has seen a boom in requests for basement CPTs since it launched this service last year. 'It's really taken off, because it's quite easy for us to get into the basement and it doesn't make a mess, because we only have to make a little hole, ' explains managing director Eric Zon, who says these factors lead clients to opt for CPTs instead of traditional boreholes.

The only limiting factor is the need to achieve the reaction needed for the rams that operate the testing equipment. 'We use 20t thrust rams, and we have to get the reaction from somewhere, so the basement must have a good strong floor or concrete ceiling, ' explains Zon.

The firm has developed a series of specialist vehicles for carrying out the tests, including mobile rigs for use in water and in buildings with limited access or low headroom, compact crawler rigs and all terrain trucks. As well as basement work, the company uses these rigs for tunnel condition surveys for transport and water companies and for various applications on the rail network.

'We would really like to get more heavily into the rail sector and are looking at building a dedicated railway rig, ' says Zon. 'At the moment we use a standard rig on a railway wagon and do the CBT through the ballast, which is very successful.

Because it is more productive than boreholes, you can gain a lot of information in only a couple of hours' possession.'

Lankelma will be demonstrating its CPT equipment at Civils 2004 on 27-29 April at the NEC in Birmingham.

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