A five-storey mixed-use development on the Swansea waterfront ran into trouble when the preliminary boreholes hit compressible alluvial silts at just 2.8 metres depth, right where the lift pit was planned. The contractor had assumed stiff glacial till based on a desk study from three streets away. That single assumption would have added £180,000 in redesign costs. In Swansea, where the geology shifts from Devonian sandstone ridges to deep estuarine clays within a few hundred metres, a rigorous soil mechanics study is what separates a feasible foundation design from a costly remedial job. We run the full chain: field sampling to BS 5930, laboratory classification, and parameter derivation under Eurocode 7. For granular strata encountered in the SA1 redevelopment zone, we often complement the investigation with SPT drilling to obtain N-values and disturbed samples, while cohesive units are profiled with the CPT test to capture continuous tip resistance and pore pressure data without sample disturbance.
In Swansea's estuarine corridor, a 1.5-metre difference in borehole termination depth can miss a buried channel fill that doubles consolidation settlement.
