A common mistake in Saint-Jerome is assuming bedrock is always shallow. The Rivière du Nord plain hides loose saturated sands deposited during the Champlain Sea era. Contractors hit water at 2 meters, keep digging, and later face differential settlement. That is a classic liquefaction scenario. The city sits at 45.778° N, in a moderate seismic zone under the NBCC 2020 hazard model. A standard borehole log is not enough. You need a targeted soil liquefaction analysis that evaluates cyclic resistance ratio (CRR) against the earthquake-induced cyclic stress ratio (CSR). We run this assessment in our ISO 17025 accredited lab using undisturbed Shelby tube samples and cone penetration data. The workflow integrates field stratigraphy with lab testing to deliver a factor of safety against liquefaction for each critical layer.
Liquefaction in Saint-Jerome is not a coastal problem. It is a Champlain Sea sediment problem, hidden under the Rivière du Nord plain.
Process and scope
Site-specific factors
The CPT rig we mobilize in Saint-Jerome is a 20-ton truck-mounted unit with a 200 kN hydraulic push. It penetrates the Champlain Sea clays and loose sands down to 25 meters without predrilling. The operator monitors sleeve friction, tip resistance, and pore pressure in real time. The raw data is screened for soil behavior type using the Robertson chart. Zones with normalized cone resistance below 60 and friction ratio above 2% flag potential liquefiable material. We then extract thin-wall samples at those depths. The lab measures the cyclic strength curve over 15 uniform loading cycles. If the CSR from the NBCC deaggregation exceeds 0.6 times the CRR, the layer fails. In Saint-Jerome, the 1732 earthquake magnitude scenario controls the hazard. Ignoring this analysis leads to bearing capacity loss during shaking — a risk no foundation engineer should accept.
Reference standards
NBCC 2020 — National Building Code of Canada, seismic hazard provisions, CSA A23.3 — Design of concrete structures, seismic ductility requirements, ASTM D5311 — Standard test method for load controlled cyclic triaxial strength of soil
Other technical services
CPT profiling for liquefaction screening
Continuous cone penetration testing with pore pressure measurement to identify loose saturated sand layers in the Rivière du Nord floodplain.
Cyclic triaxial testing
Undrained cyclic loading on Shelby tube specimens to determine CRR at 15 uniform cycles. Results corrected for fines content and overburden pressure.
Post-liquefaction settlement analysis
Estimation of volumetric strain and ground surface settlement using the Ishihara and Yoshimine procedure, calibrated to Saint-Jerome's stratigraphy.
Typical parameters
Frequently asked questions
Is Saint-Jerome in a high seismic risk zone?
Saint-Jerome is in a moderate seismic hazard zone under the NBCC 2020 model. The design ground motion for Site Class C is typically around 0.3g to 0.5g for the 2% in 50-year hazard. The presence of loose Champlain Sea sands can amplify shaking and trigger liquefaction even at moderate PGA levels. A site-specific analysis is always recommended.
What depth do you investigate for liquefaction?
We investigate the upper 20 to 25 meters. In Saint-Jerome, the critical layers are usually between 3 and 12 meters depth, where the Rivière du Nord alluvial sands are loose and saturated. Deeper layers are typically overconsolidated glacial till and pose lower risk.
How long does a liquefaction study take?
Fieldwork with CPT and sampling takes one to two days on site. Lab testing for cyclic triaxial requires approximately three weeks due to specimen preparation and consolidation stages. The final report with factor of safety calculations is delivered within four weeks from field mobilization.
What does a soil liquefaction analysis cost in Saint-Jerome?
A complete liquefaction assessment including CPT profiling, undisturbed sampling, and cyclic triaxial testing on two specimens typically ranges from CA$3,360 to CA$5,470, depending on access conditions and the number of critical layers identified. More info.