Newmarket's development surged after the Holland River canal reached the town in the 1850s, transforming a rural outpost into a manufacturing hub. That industrial growth now sits on a complex glacial stratigraphy. The Oak Ridges Moraine dominates the north. The Holland Marsh lowlands press up from the east. Between them, dense Halton Till interbeds with pockets of glaciolacustrine silt. Standard penetration testing often smears these thin, sensitive layers. CPT (Cone Penetration Test) resolves them. Performing a triaxial shear test on the silt recovered from a CPT-identified weak zone provides direct undrained shear strength. The boundary between till and marsh organics shifts sharply across a single lot. Continuous CPT data reveals that transition without gaps. We use it to map bearing stratum depth and avoid differential settlement in the Newmarket area.
In the Halton Till, a normalized friction ratio below 1.2% with pore pressure spikes signals a dilatant silt lens—not a sand layer.
Methodology and scope
Local considerations
In Newmarket, we frequently see undetected organic clay seams at the till-marsh interface. A CPT rig picks up the drop in tip resistance immediately. But a borehole with SPT might miss a 200 mm layer entirely. That layer controls consolidation settlement. The risk is not bearing capacity failure. The risk is long-term differential settlement cracking the slab. Another issue is pile plugging in the dense basal till. Driving H-piles without knowing the CPT profile can lead to refusal at shallow depth, before reaching the designed tip elevation. We use CPTu pore pressure data to check for the presence of artesian conditions in the sand lenses within the till. Ignoring a confined aquifer during excavation causes base heave.
Applicable standards
ASTM D5778-20 (Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils), Ontario Building Code (OBC) / NBCC 2020, CSA A23.3-19 (Design of concrete structures – geotechnical input), ASTM D6067/D6067M-17 (Piezocone dissipation)
Associated technical services
Piezocone Profiling (CPTu)
Continuous logging of qc, fs, and u2. We provide corrected qt profiles, normalized soil behavior type charts, and dissipation tests for groundwater equilibrium pressure. Essential for profiling Newmarket's varved deposits.
Seismic CPT (SCPTu)
Addition of a geophone module behind the cone to measure shear wave velocity (Vs) during a pause in penetration. Used to calibrate the low-strain stiffness of the Oak Ridges Moraine tills for seismic site classification per NBCC.
Typical parameters
Frequently asked questions
What is the typical cost range for a CPT investigation in Newmarket?
Based on the local market and typical mobilization within the Greater Toronto Area, a CPT (Cone Penetration Test) investigation in Newmarket typically ranges from CA$230 to CA$310 per meter of penetration. The final cost depends on the depth, the number of dissipation tests required, and whether seismic (SCPTu) modules are needed.
Can CPT refusal damage the cone in Newmarket's till?
Yes, refusal in the dense Halton Till or on a cobble is common. The load cell is rated for high stress. But pushing a cone against a hard cobble at full thrust can cause eccentric loading damage. The operator monitors the sleeve friction ratio and stops the push if the signal spikes asymmetrically. We often pre-drill through the upper gravelly zone to protect the cone.
How does CPTu help with liquefaction assessment in Newmarket?
CPTu provides a continuous profile of normalized tip resistance and friction ratio. This data feeds directly into the Robertson (2009) method for liquefaction triggering. The high sample rate captures thin sand layers interbedded in the glaciolacustrine silt that the NCEER method, based on SPT blow counts, would likely miss.
What depth do you typically reach in the Oak Ridges Moraine?
It varies sharply. In the northern parts of Newmarket, the till matrix is very dense and we often reach refusal between 15 and 25 meters depth. Closer to the Holland River, the dense till is deeper and we can push past 30 meters through the overlying soft sediments before hitting the competent lodgment till.