CPT Testing in Glasgow: Rapid Site Investigation for Urban Projects

A warehouse extension near the Clyde in Glasgow's East End looked straightforward on the drawings. The borehole logs from the 1990s suggested a metre of fill over sand. But the site sat on the old floodplain, with the river less than 300 metres away, and groundwater would determine whether the slab could go straight on grade or needed piles. Two days of CPT pushed cones to 18 metres at six locations, mapping soft silts the historic logs had missed entirely. We see this pattern across Glasgow: legacy ground data that does not match what is actually there. The Cone Penetration Test delivers a continuous strength and stratigraphy profile in a single push, which is why we rely on it for sites where time matters and the subsurface is uncertain.

CPT gives you a near-continuous log with 2 cm resolution. No recovery issues, no disturbance, just cone resistance and pore pressure all the way down.

Process and scope

Glasgow's population sits around 630,000, and the city is pushing brownfield redevelopment hard along the Clyde corridor. That means sites with complex made ground histories: old dock backfill, buried foundations, demolition rubble. Standard boreholes sample at discrete intervals and can miss thin soft layers. CPT records cone resistance, sleeve friction, and pore pressure at 2-centimetre spacing, so a 15-metre push generates over 700 data points. We run 20-tonne track-mounted rigs that can work on tight city-centre plots without excessive disturbance. Data processing follows BS 5930:2015 and BS EN ISO 22476-1, with soil behaviour type charts giving a first-pass classification on screen while the test is running. Where the ground is variable, pairing CPT results with a targeted SPT drilling programme gives us both continuous profiling and discrete disturbed samples for index testing.

Site-specific factors

Glasgow's industrial past left a legacy of fill that varies from ash and clinker to demolition debris, often over soft alluvium along the Clyde and its tributaries. Much of the city centre is built on the Glasgow Upper and Lower till sequences, which are overconsolidated but can contain water-bearing sand lenses. A developer who treats the whole site as stiff glacial till risks designing foundations that are fine for the till but under-designed where the till pinches out against buried channels. CPT picks up these transitions in real time. We have seen projects where a single borehole placed in a pocket of dense material gave a false picture of site-wide bearing capacity; five CPT soundings across the same footprint showed the soft channel within half a day. The other risk is pore pressure: low-permeability silts around the Clyde can develop excess pore pressure during construction, and a dissipation test during CPT tells you how fast that pressure will bleed off.

Typical values

Parameter	Typical value
Cone capacity	20 MPa standard; 50 MPa available
Maximum push depth	Typically 20-25 m in Glasgow glacial deposits
Measurement interval	2 cm (continuous)
Parameters recorded	qc, fs, u2 (pore pressure) standard; Vs option
Friction sleeve area	150 cm²
Data reporting	BS 5930 + BS EN ISO 22476-1 compliant logs
Pore pressure dissipation tests	Included on request

Complementary services

Full CPTU with pore pressure measurement

Piezocone testing that records cone resistance, sleeve friction, and dynamic pore pressure simultaneously. Includes dissipation tests at specified depths to estimate consolidation characteristics and permeability in fine-grained soils. Reports delivered with soil behaviour type classification.

Combined CPT and SPT ground investigation

Integrated campaign where CPT provides the continuous profile and SPT boreholes provide disturbed samples for laboratory index testing. Ideal for sites with variable made ground where classification from cone data alone needs ground-truthing. Covers BS 5930 logging and factual reporting.

Questions and answers

How much does a day of CPT testing cost in Glasgow?

A standard day of CPT on a Glasgow site typically falls between £140 and £170 per hour of rig time, with most jobs requiring four to six hours depending on access and number of soundings. Mobilisation within the city is generally straightforward and we include it in the quote. Every site is different, so we price the work based on depth, number of pushes, and whether you need dissipation tests or seismic add-ons.

Can CPT replace boreholes on a Glasgow brownfield site?

CPT can replace some boreholes but not all of them. It gives you a continuous strength and stratigraphy profile that boreholes miss, but it does not recover a sample. On brownfield sites with demolition rubble or obstructions, we often recommend a mixed approach: CPT to map the soft zones and buried channels, plus a few targeted boreholes or trial pits where you need to see the fill composition and take samples for contamination testing.

What depth can you reach with CPT in Glasgow's glacial deposits?

In the overconsolidated tills typical of central Glasgow, a 20-tonne CPT rig can usually push to 20–25 metres before reaching refusal. The exact depth depends on the stone content and degree of cementation in the till. If you need deeper profiles, we switch to a combination of CPT for the overburden and rotary drilling for the rockhead.

How long does it take to get the CPT report after testing?

Factual data is available the same day: you get cone resistance, friction ratio, and pore pressure plots before the rig leaves site. The interpretive report with soil behaviour type classification, bearing capacity estimates, and correlation to BS 5930 descriptions follows within three to five working days, depending on the number of soundings.