In Kamloops, the combination of river-terrace deposits and the city’s moderate but real seismic hazard makes assumptions about ‘firm ground’ a gamble. We regularly see geotechnical reports that overlook the liquefaction susceptibility of saturated silty sands along the Thompson River floodplain, particularly north of the confluence with the South Thompson. A standard SPT refusal at depth doesn’t automatically rule out a loose lens above the water table that could trigger during a design earthquake. The 2020 edition of the National Building Code of Canada assigns Kamloops a higher spectral acceleration than many consultants realize, which directly influences the cyclic stress ratio we plug into our simplified procedures. When a client is placing a critical structure on post-glacial lacustrine soils, we often pair the liquefaction screening with a CPT investigation because the continuous tip resistance and sleeve friction profile catches thin, contractive layers that a split-spoon sampler can miss entirely. It’s not about running a standard checklist; it’s about understanding how the local fluvial stratigraphy talks back to the seismic demand.
A factor of safety above 1.0 from a single borehole is not a free pass; the spatial variability in Kamloops’ glaciofluvial soils demands a probabilistic look at the entire footprint.
