Pickering sits on a complex glacial stratigraphy — primarily the dense, silty-clay Halton Till overlying the deep Thorncliffe Formation. Groundwater can appear as a perched table within the till, often just 3 to 5 meters below grade. The city's proximity to the Duffins Creek watershed means pore pressures shift seasonally, and a dry cut in August can be wet in November. This makes the geotechnical design of deep excavations here a task that demands more than a generic shoring schedule. It requires a hydrogeological read of the site before the first bucket hits the ground. For projects near the Pickering Nuclear Generating Station, we often integrate seismic refraction profiles to map bedrock depth without disturbing sensitive adjacent zones.
In Pickering's Halton Till, jointing and perched water control the excavation design, not just the undrained shear strength.
