BBGE proves it is worth its salt in Ireland

Completes first contract as new integrated business

Balfour Beatty Ground Engineering (BBGE) has completed its first contract in Ireland since aligning its divisional businesses in the country just two months ago.

The geotechnical specialist was awarded the contract by P. Elliot & Co Ltd to prepare the ground for the construction of a new road maintenance depot for Dun Laoghaire Rathdown County Council.  The finished depot, based at Ballyogan, south Dublin, will provide essential maintenance facilities for the Dublin orbital M50 motorway, which is currently undergoing a £1billion upgrade.

This 10-day contract involved mainly ground improvement works, which were carried out by BBGE division Pennine, and presented the team with a number of challenges; these included having to contend with variable terrain and working in close proximity to newly built concrete walls.

Commenting on the project, James McNeill, BBGE Business Development Manager, Ireland says, “This contract and the various enquiries we have in the pipeline indicate that there is a real interest for BBGE’s integrated approach in Ireland.  Clients are responding well to our ability to recommend the best geotechnical technique for any brief from the range of services we now offer under one umbrella.”

He continues, “For this particular project, our ability to provide faster production times while keeping costs down were also instrumental in us securing the work.”

In September, BBGE in Ireland united its divisional businesses of Pennine, Stent, Branlow, Balfour Beatty GeoEnvironmental and Testal to provide an integrated ground engineering service for customers. The divisions bring specialist services in the areas of ground improvement; piling and foundations; mini and micro piling; contaminated land and remediation; testing and analysis.

Project Description

Pennine was tasked with reinforcing the ground on the Ballyogan site, which consists of up to 4m of firm and stiff clay fill overlying Glacial Till in the form of natural gravelly clay. Part of the site was also based on a natural slope, which was levelled with granular fill resulting in variable and unstable ground for construction.

Pennine used a Top Feed poker to install Vibro Stone Columns (VSCs) at a depth of up to 6m to stabilise the ground and keep settlements within tight specifications of 20mm, before construction could begin on a utilities building, which will be used to store materials such as road salt to grit the nearby M50 motorway, and a two-storey office block.  The VSCs improved load bearing capabilities in areas holding heavy items, such as the bays used to store the road salt, which will need to support loads of up to 50kPa.

VSCs were also installed at external areas including an access road, as well as the unusually large 2.7m wide foundations of a 5m tall gabion wall, which is being used as a free-standing boundary feature for aesthetic reasons rather than its usual function of a retaining structure.

During the project, Pennine had to keep a 3m distance from newly constructed Reinforced Concrete retaining walls when installing some of the VSCs, in order to avoid damaging them. These walls had been built for basements, as part of the new buildings. As they were newly built, the concern was that the walls may not yet have reached their full strength and been able to support the weight of Pennine’s rig or withstand the vibrations from installing the stone columns.  

Construction of the depot will commence once the ground works are complete and is due for completion in summer 2010.