Geoscience Ireland (GI) is pleased to report that one of its members Fehily Timoney (FT)  has won the Association of Consulting Engineers of Ireland Award for Project of the Year. Another GI member Priority Geotechnical undertook ground investigations for the project.

Fehily Timoney was awarded as lead consultant for the Dunkettle Interchange Upgrade Scheme. John Sisk & Son Ltd appointed Fehily Timoney as lead and subconsultants Ramboll UK and Clandillon Civil Consulting Ltd. to carry out the design for the scheme

The Dunkettle Interchange is the junction of four national roads; the M8 Cork to Dublin Motorway, the N25 Cork to Waterford/Rosslare route, the N40 Cork South Ring Road and the N8 Dunkettle to Cork city National Route. The upgrade covered 10km of new road links constructed across a 0.5km2 site, one new grade separated junction, four new roundabouts, 2.9km of new cycleways and walkways and 58 new structures, including bridges, retaining walls, gantries and culverts.

Subcontractors Priority Geotechnical (also a Geoscience Ireland member) and Ground Investigations Ireland were appointed to carry out ground investigation phases between 2019 and 2021 to inform the design development. As part of these investigations, a total of 376 exploratory holes were drilled across the site. Methods used included cable percussion, rotary core, trial pits and cone penetration tests.

The ground investigations indicated variable ground conditions across the site, comprising made ground, overlying soft and compressible alluvium, dense sands and gravels, soft glacial till and bedrock at variable depths as reported in Ground Engineering Magazine i.e.  

“The made ground varies from 0m deep in some places to around 8m deep in other places,” explains FT geotechnical team lead Tom Clayton.

“All of that overlies soft and very compressible alluvium and then dense fluvial sands and gravels with stiff glacial till underneath. The bedrock depth varies hugely because there are multiple glacial channels that run through the site.

“We had bedrock at surface at the north of the site, and bedrock close to surface at the very southern extent of the site. In the middle of the site, we drilled a borehole down to 65m and didn’t find any bedrock.”

Photo shows ACEI President Anne Marie Conibear presenting the Award to Tom Clayton and Sinead Timoney and the FT Team.