Newbridge sits on the River Liffey floodplain, with groundwater often just 1.5 metres below the surface in the town centre. That shallow water table, combined with pockets of loose alluvial sand deposited over centuries, creates the exact conditions where seismic shaking can trigger soil liquefaction. In our lab we have seen silty sands from boreholes near the Curragh that lose nearly all bearing capacity when saturated and vibrated. A CPT test gives us continuous cone resistance data to identify these loose layers with precision, while MASW measures shear wave velocity profiles to feed into the Eurocode 7 liquefaction assessment framework. For any project on the floodplain — from the Whitewater extension to industrial units near the M7 — we recommend a liquefaction screening as part of the ground investigation. The geology here does not forgive shortcuts.
In saturated alluvial sands with N-values below 10, we calculate post-liquefaction settlements exceeding 100 mm — a number that demands engineering attention.
