// News

08 September 2008

The McArdle Group has secured a first in the Irish market for large-scale soil stabilisation. The civil engineering group has already pioneered the use of modern soil stabilisation techniques alongside traditional earth-moving capabilities in the UK for more than a decade.

Working for main contractors Ascon and Dragados, McArdle has been responsible for successfully stabilising over 17 kilometres of the capping layer for a new dual carriageway around Waterford City, in the southeast.

A large volume of road projects is currently under way in Ireland, including the N25 Waterford by-pass. The work at Waterford was spread throughout the site, but much of it was concentrated south of the River Suir crossing at Kilmeaden.

McArdle's successful involvement is a ringing endorsement of the increased viability of soil stabilisation techniques in an Irish context.

Experience and benefits

Large-scale soil stabilisation is a tried and tested technique in the UK, where McArdle uses its own equipment fleet for many of these types of projects.

But it is still very much in its infancy in Ireland. McArdle brought a depth of knowledge and experience to the Waterford project - not only from its UK work but also from contracts as far away as the Caribbean.

The preliminary earthworks in Waterford were undertaken by the main contractors, and McArdle was brought in for its expertise on the stabilisation element.

"Soil stabilisation provides a massive saving on the importation of materials on site through the treatment of on-site soils," Mark Roberts, Works Manager for McArdle Stabilisation, explains.

"By using the system to treat material for the capping layer in road construction, even more significant savings can be made compared with the more usual stone capping approach," he says.

Large-scale

McArdle used one of its self-propelled Wirtgen 2500SK soil stabilisation units and a large self-contained spreader.

While the Wirtgen is an increasingly common sight in the UK, it's still an unusual one in Ireland. So much so that when McArdle was awarded the Waterford contract, no Irish contractors had experience of running such large-scale self-propelled stabilisation machinery.

Small-scale stabilisation projects can be successful using towed equipment. But Roberts says that for projects of the scale of the Irish one, you cannot beat the benefits of this large self-propelled machinery, operated by an experienced crew.

McArdle's spreader of choice is the Terra Gator 2204. The stabilisation operations in Waterford began with the placement of binding using a Terra Gator equipped with a Streu Master tank and spreader unit.

Quality control

McArdle maintained stringent quality control when it came to material for the stabilisation. Maintenance requirements can also increase sharply when material with a high stone content is being stabilised.

To counteract the high stone content of the material on the Waterford site, the McArdle team fitted a rock specification drum for greater durability.

The crew constantly monitored the drum's mixing tools, and application rates were also a key part of the process, with a sophisticated control system to monitor and regulate inputs.

Media spotlight

McArdle's key role in this project has also been covered in the September 2008 edition of Earthmovers.