Drummondville sits on thick post-glacial Champlain Sea clay, a legacy of the last ice age that left deep compressible deposits across the St. Lawrence Lowlands. Spring thaws and heavy fall rains push the water table within 1.5 m of the surface in many neighborhoods. That combination — soft saturated clay under a thin desiccated crust — makes the geotechnical design of deep excavations a non-negotiable step before any basement, underground parking, or utility trench. Without a proper study, excavation walls can yield, pumps can fail, and adjacent streets can settle. We start every project by correlating the local clay stratigraphy with the presuremeter test to measure lateral stiffness in situ, then cross-check the data against the consolidation test to predict long-term settlement under dewatering.
Champlain Sea clay in Drummondville can lose 50% of its undrained strength within meters of a deep excavation face. Plan accordingly.