Belfast's industrial legacy means the subsurface is rarely straightforward. The Lagan Valley conceals a sequence of soft estuarine clays, known locally as sleech, overlying dense glacial till. Standard boreholes often struggle to capture the transition between these layers with enough resolution for settlement calculations. CPT testing cuts through that ambiguity by providing a continuous, high-resolution profile of tip resistance, sleeve friction, and pore pressure in real time. On a recent city centre project near the River Lagan, our team used a 20-tonne CPT rig to push through 28 metres of soft clay before refusal on till, identifying a thin sand lens at 11 metres that would have been missed by SPT alone. For sites where the water table sits less than 2 metres below ground, we deploy piezocone (CPTu) to track excess pore pressure dissipation during pauses in penetration, which feeds directly into consolidation settlement estimates for shallow foundations. In areas underlain by the Mercia Mudstone Group, the friction ratio data helps distinguish weathered bedrock from intact material without coring every hole.
A single CPT sounding in Belfast's Lagan Valley can resolve more stratigraphic detail in four hours than a week of conventional drilling in mixed soft soils.
