A 20-tonne excavator bucket cuts through the silty clay overburden on a North Bay site, exposing the contact with the Precambrian rock beneath. That is the simplest definition of an exploratory test pit. Our crews deploy tracked excavators sized to access tight lots near Lake Nipissing, opening trenches down to 4.5 metres where the glacial stratigraphy needs direct observation. No indirect inference. No waiting for lab turnaround on a split-spoon sample. The exposed wall shows you the real layering, the groundwater seepage horizon, and the fractured rock head. For projects within the City of North Bay's building permit jurisdiction, we log each pit against Ontario Regulation 332/12 and the relevant CSA A23.3 provisions for exposure classification. The goal is straightforward: give the structural engineer a defensible bearing stratum and give the contractor an honest picture of what the excavator will encounter during bulk earthworks. When the overburden is thin and the shield rock is shallow, the test pit remains the fastest way to confirm refusal depth before committing to a footing design that assumes soil where none exists.
A test pit wall is the only geotechnical report that the contractor can read without a legend.
