A surprising number of domestic extensions in Bath start digging and hit something unexpected—buried cellars, springs, or the notoriously variable Fuller's Earth formation. An exploratory test pit eliminates that guesswork before the first brick is laid. We mobilise compact excavators to tight-access terraces in areas like Lansdown or Widcombe, exposing shallow strata so the ground model reflects reality, not desk-study assumptions. The method follows BS 5930:2015, and every logged section is photographed, sampled, and tied to chainage. In Bath's sloping terrain, a single test pit often reveals more about the critical near-surface behaviour than a dozen boreholes; we pair it with Atterberg limits testing whenever cohesive layers need classification for bearing capacity checks under Eurocode 7.
A single well-logged test pit in Bath often delivers more actionable near-surface data than half a dozen driven boreholes.
Service characteristics in Bath
Critical ground factors in Bath
A six-storey mixed-use scheme on Lower Bristol Road hit groundwater at 1.8 metres during initial piling trials—the desk study had shown the water table much deeper. Our exploratory test pit dug 20 metres upslope confirmed a perched aquifer trapped above the Lias clay, entirely missed by window sampling alone. Without that physical exposure, the contractor would have proceeded with an under-designed dewatering system. In Bath, buried service trenches, old mine adits, and unrecorded basement vaults create singular risk profiles; a mechanical excavation inspected at close range remains the most reliable way to catch these hazards before they escalate into claims. Collapse of unshored faces in granular layers is a real site safety concern, which is why all pits deeper than 1.2 metres follow the confined-space and shoring protocols of the Health and Safety Executive's HSG150.
Our services
Each pit programme in Bath is configured around access constraints, the target geology, and the specific design question—whether it is foundation bearing, drainage, or slope stability.
Foundation Verification Pits
Excavated at proposed spread footing locations to confirm bearing stratum quality, log the depth to rockhead, and collect U100 tubes for laboratory shear strength testing.
SuDS Infiltration Pits
Falling-head permeability tests run directly in the pit, with logged soil horizons correlated to BRE Digest 365 infiltration rates for sustainable drainage design.
Slope Investigation Trenches
Continuous shallow trenches across suspected slip planes on hillside sites, logging colluvium thickness and piezometric levels to feed stability back-analysis.
Quick answers
What does an exploratory test pit in Bath typically cost?
For a standard programme of two to three pits with machine access, logging, photography, and a factual report, the range is £450 to £640 per pit plus mobilisation. The final figure depends on traffic management requirements, depth, and whether infiltration testing or U100 sampling is added.
How does a test pit differ from a borehole for a Bath hillside site?
A test pit gives continuous visual exposure of the near-surface layers, letting you see bedding orientation, fracturing, and seepage directly. Boreholes are better for depth, but a pit answers the shallow questions—fill thickness, foundation level, and drainage—more completely for low-rise structures.
Can you excavate a test pit inside a listed Bath property with restricted access?
Yes, we use 1.5-tonne mini excavators that fit through standard doorways after temporary removal of door leaves. For tighter spaces, we can switch to hand-dug pits, though the achievable depth is usually limited to around 1.5 metres.