With over 330 lakes and a topographic relief carved by a billion-year-old meteorite impact, Sudbury’s ground profile is anything but predictable. The city sits at roughly 347 metres above sea level, straddling the rugged contact between the Canadian Shield and glacial deposits that can vary from dense till to soft lacustrine clay in less than a hundred metres. When a drill rig can't access a tight backyard on Ramsey Lake Road or a slope below the old INCO smokestack, we open the ground with an exploratory test pit. It’s the most direct way to see what’s actually under the surface—no extrapolation, no guesswork. For projects that demand precise bearing capacity values, we often combine the test pit data with a plate load test to verify in-situ stiffness right at footing elevation.
Nothing replaces the certainty of seeing the soil face with your own eyes—test pits give us that window in Sudbury's erratic overburden.
Our approach and scope
Site-specific factors
The National Building Code of Canada (NBCC) places Sudbury in a region where frost penetration routinely exceeds 1.5 metres, and the local geology adds an extra layer of risk that desk studies alone can't resolve. Skipping an exploratory test pit in the Sudbury Basin means gambling on the continuity of the overburden—we have seen cases where a footing designed for silty sand ended up bearing on isolated lenses of sensitive clay that lost half its strength upon remolding. The CSA A23.3 standard for concrete structures assumes the foundation soil behaves as predicted; when it doesn't, differential settlement cracks appear within the first two freeze-thaw cycles. A single day of test pit investigation costs a fraction of what it takes to underpin a settled foundation on Lasalle Boulevard or repair a retaining wall that rotated because the backfill zone was never properly characterized.
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Reference standards
O. Reg. 213/91 (Construction Projects – Excavation Safety), CSA A23.3 (Design of Concrete Structures – Foundation Provisions), ASTM D2488 (Visual-Manual Soil Description), NBCC 2020 Part 4 (Structural Design – Geotechnical Requirements)
Complementary services
Overburden Stratigraphy Logging
Detailed logging of soil layers, moisture condition, and consistency by an experienced geotechnical technician familiar with Sudbury's glacial stratigraphy.
Bedrock Depth Confirmation
Direct measurement of bedrock surface elevation and assessment of weathering grade, critical for footings bearing on the Shield.
Groundwater & Seepage Assessment
Observation of groundwater ingress rate and perched water zones during excavation, with documentation for drainage design.
Typical parameters
Frequently asked questions
What does an exploratory test pit cost in Sudbury?
For a standard project within Greater Sudbury, budget between CA$760 and CA$1,040 per pit. The final number depends on access, depth, and whether we need to bring in a larger excavator to handle bouldery till.
How deep can you go with a test pit in Sudbury?
We typically go to 3.5 or 4.0 metres with a standard excavator. With proper shoring or a stepped bench cut, we can reach 6.0 metres. Beyond that, we'd recommend switching to SPT drilling for deeper investigation.
Do I need a locate before the test pit is dug?
Yes, Ontario law requires a full utility locate (Ontario One Call) before any excavation. We handle the locate request as part of our service, but it must be obtained and valid before the machine breaks ground.