Subsurface water behaves differently beneath Aldershot than it does through the fractured shale of Tyandaga. A standard lab permeameter test often misses the joint-controlled flow paths that govern real drainage rates. In Burlington, where the Queenston Formation underlies much of the city, field permeability testing becomes the only reliable way to quantify hydraulic conductivity at the scale that matters for dewatering design. The Lefranc method handles soil and weathered rock intervals with precision, while the Lugeon test targets discrete fractures in the competent shale bedrock that runs under the Niagara Escarpment's toe. Our team runs these tests using ASTM D4630 procedures, feeding directly into grouting programs and deep excavations stability analyses across Halton Region.
A Lugeon value above 25 typically indicates open fractures that will dominate the site's groundwater regime, demanding a grouting program before any major excavation proceeds.
