Drilling in the decomposed granite that underlies much of Pomona often reveals fractures that control groundwater flow in ways lab samples simply miss. The alluvial fans spreading from the San Jose Hills create stratified deposits where permeability can shift dramatically within a few vertical feet. Our team runs Lefranc tests in soil and Lugeon packer tests in fractured rock to measure hydraulic conductivity directly in the borehole, avoiding the disturbance that comes with sampling and remolding. For projects near the 60 Freeway corridor or the Fairplex, where stormwater infiltration and retaining wall drainage become design-critical issues, we combine these field readings with grain size analysis to correlate in-situ behavior with index properties. The IBC requires site-specific drainage assessments, and a Lefranc test delivers that data without the cost of a full pumping test when you are working in a single exploratory boring.
A single Lugeon test in fractured Pomona bedrock reveals more about seepage paths than a dozen remolded lab permeameter samples ever could.
