Most construction projects begin with borehole drilling. But drilling gives you information at a single point — not across the whole site. Here are five situations where a geophysical survey should come first.
Old mine workings, former industrial use, filled land, or known sinkhole-prone geology are situations where knowing what is between the boreholes matters as much as what is in them. ERT and GPR surveys can map these hazards across the entire site.
Roads, pipelines, railway lines, and canals pass through variable geology. MASW seismic and ERT surveys provide continuous profiles along the alignment — catching zones of weak soil, shallow rock, or groundwater that isolated boreholes would miss.
If two boreholes 50m apart show completely different soil profiles, you have lateral variability you do not understand. A geophysical survey between the boreholes resolves what is happening — and tells you whether to drill more or whether you already have enough information.
Borehole drilling has a very small chance of intersecting a cavity — GPR and ERT surveys cover large areas and are specifically designed to detect subsurface voids before they cause foundation problems or pavement collapses.
Any excavation below the groundwater table needs groundwater information. ERT can map the water table, identify permeable and impermeable layers, and flag zones of high groundwater that will affect dewatering design and cost.
Geophysical surveys do not replace boreholes — they make your boreholes more effective and your site characterisation more complete.
