A hillside plot in Sketty behaves nothing like a valley-bottom site in Morriston. The former sits on well-drained glacial till over Devonian sandstone, while the latter contends with alluvial silts and a water table that rises fast after a Swansea downpour. Those differences aren't academic—they dictate whether a cutting stays put or creeps toward the boundary fence over the next decade. We run the numbers on both scenarios, factoring in the 1,200 mm of annual rainfall that saturates the local slopes and the legacy of mining that riddles the ground beneath Kilvey Hill. Before you commit to a cut-and-fill scheme, pairing the analysis with a CPT test clarifies the drainage profile in the valley clays, and a MASW survey gives us the shear-wave velocity needed for seismic checks under BS EN 1997.
A Swansea slope that stands at 1.3:1 in summer can fail at 2.5:1 in February—seasonal pore pressure isn't a footnote, it's the design case.
