Drummondville sits on the St. Lawrence Lowlands, where the subsurface is dominated by marine clays and silts left by the Champlain Sea. These fine-grained soils are highly sensitive to changes in moisture and can lose strength rapidly if disturbed. For any retaining wall project here, we start by characterizing the clay's undrained shear strength and its sensitivity to remolding. This is critical: the local Leda clay can transition from a stiff deposit to a fluid-like slurry under loading. We combine borehole data with calicatas exploratorias to map lateral variability and identify any sand lenses that could affect drainage behind the wall. That initial site characterization shapes every design decision.
In Drummondville clays, frost-induced lateral pressures can exceed active earth pressure by a factor of three. Drainage is not optional.