A recent basement excavation near Swindon's Old Town hit groundwater at just 2.3 metres, despite borehole logs suggesting a dry formation. The contractor had to halt work for three weeks while temporary dewatering was arranged—an expensive delay that a field permeability test would have flagged early in the design phase. Swindon sits on a complex transition between the Upper Jurassic limestone of the Cotswold fringe and the overlying Gault and Kimmeridge clays of the Upper Thames valley. That geological boundary creates unpredictable seepage paths, especially where fissured limestone interfaces with low-permeability clay. The Lefranc test gives reliable point measurements in soil and weathered rock, while the Lugeon method handles the fractured bedrock zones that underlie much of the town centre. Both procedures follow BS 5930:2015 and BS EN ISO 22282-2, providing the hydraulic conductivity values that drainage engineers and structural designers need for soakaway sizing, basement waterproofing, and cut-off wall specification. When the borehole is already open for an SPT drilling campaign, adding a packer test adds minimal mobilisation cost yet transforms the hydrogeological picture of the site.
A single Lugeon test in fractured limestone can reveal more about site drainage than a dozen lab permeameter tests—scale matters enormously in Swindon's mixed geology.
