North Bay sits squarely on the Canadian Shield, where the Precambrian bedrock is laced with fractures that control groundwater flow more than the rock matrix itself. In the Champlain Sea clay plains and sandy outwash deposits that fringe Lake Nipissing, hydraulic conductivity can swing from 1×10⁻⁷ cm/s in a stiff clay to 1×10⁻² cm/s in a clean sand. Our field permeability testing program uses the Lefranc variable-head method in soil and the Lugeon constant-pressure method in rock to put a defensible number on that variability. Without site-specific k-values, dewatering design turns into guesswork, and cutoff wall depths get picked on a hunch. We run these tests as part of broader geotechnical campaigns, often pairing them with SPT drilling to log stratigraphy and test pits where shallow groundwater conditions need direct observation before committing to a deep pumping system.
A Lugeon value below 1 in North Bay granite rarely needs grouting; above 5, the fractures are open enough to warrant a targeted curtain treatment.
