The Silurian dolostone bedrock across London sits under a blanket of glacial till and glaciofluvial deposits that can change drastically within a few hundred meters. You might find dense Halton Till on one lot and loose sand just down the street. Standard drilling here can miss thin, soft layers that control settlement. We run electric cone penetration tests to get a continuous, high-resolution profile of the subsurface. By pushing the cone through the overburden, we capture tip resistance, sleeve friction, and dynamic pore pressure in real time. This data feeds directly into bearing capacity checks, liquefaction assessments, and pile design. For sites near the Thames River with thick alluvium, we often pair CPT sounding with grain size analysis to refine the soil behavior type classification from the Robertson charts.
A single CPT sounding replaces several SPT boreholes for stratigraphic profiling, cutting field time in half.
Our approach and scope
Site-specific factors
A developer we worked with on Wharncliffe Road hit a saturated silt lens at 6 m depth while excavating for a three-level underground parking garage. It was not flagged during the preliminary borehole program. The contractor lost a week stabilizing the excavation with wellpoints. After that, they called us in. We ran four CPT soundings around the perimeter in one afternoon. The friction ratio and pore pressure profiles mapped the lens across the entire southwest corner. No more surprises. Relying solely on SPT data in London's complex till stratigraphy leaves you blind to these soft interbeds. The continuous nature of CPT data means you see the lens before you hit it.
Video resource
Applicable standards
ASTM D5778-12, NBCC 2015, CSA A23.3-14
Other technical services
Standard CPTu Sounding
Full cone penetration test with tip resistance (qc), sleeve friction (fs), and pore water pressure (u2) measurement. Includes real-time data acquisition and a field log with soil behavior type.
CPT with Shear Wave Velocity (SCPTu)
Seismic cone downhole test for direct measurement of Vs. Every 1 meter we stop, generate a shear wave from the surface, and record the arrival time. Provides the small-strain stiffness needed for seismic site classification per NBCC.
Typical parameters
Quick answers
How deep can CPT go in London's till?
Most commercial jobs stop between 15 and 25 meters. The Halton Till and Port Stanley Till are overconsolidated and dense. Our 20-tonne rig with 200 kN thrust can typically push through these tills to refusal on bedrock. If we hit a hard boulder or the dolostone surface early, the cone reaches its tip stress limit and we stop. For deeper profiles, we may pre-drill through the upper stiff crust.
Do you provide soil behavior type classification from CPT data?
Yes. We process the raw qc, fs, and u2 data using the normalized soil behavior type (SBTn) chart by Robertson (2009). The report includes a continuous SBT log alongside the measured parameters. This classifies the soil into zones—sands, silts, clays—based on tip resistance and friction ratio, corrected for overburden stress and pore pressure.
What is the cost of a CPT test in London, Ontario?
Budget CA$220 to CA$350 per sounding for a standard CPTu to 15–20 m depth with a field log. Mobilization is separate and depends on site location within London. Seismic CPT (SCPTu) runs higher due to the extra downhole testing time and data processing.
Can CPT replace boreholes for my foundation design?
It can significantly reduce the number of boreholes. CPT gives you continuous data, which is superior for detecting thin layers. But it does not recover soil samples. We recommend a hybrid program: a few boreholes with SPT and sampling for index testing, calibrated against several CPT soundings across the site. This gives you both material identification and high-resolution stratigraphy.