The National Building Code of Canada (NBCC 2020) makes specific demands on granular classification, and in a place like St. Albert, where glaciolacustrine clays sit beside coarse outwash deposits, the difference between a silt and a clay has real structural consequences. Our grain size analysis combines mechanical sieving for the coarse fraction with a hydrometer sedimentation test for fines passing the No. 200 sieve, following ASTM D422 and the hydrometer-specific ASTM D7928. We have run these dual-method tests on soils from the city’s northwest industrial parks, the residential expansions near Ray Gibbon Drive, and the mixed terrains south of Big Lake, where the contact between sand lenses and sensitive clay layers demands a complete particle-size curve to get the soil classification right. Because the hydrometer portion is temperature-sensitive and requires precise preparation with sodium hexametaphosphate as a dispersing agent, we process these samples in a controlled laboratory environment, not in a field trailer, so the results hold up when a geotechnical engineer needs them for frost heave susceptibility or drainage design in the Sturgeon River basin. When the project involves deep foundations in the city’s lacustrine plains, we often pair the grain size distribution with an Atterberg limits test to confirm plasticity characteristics, since a soil’s behavior under load changes dramatically once the fines content exceeds 15 percent in this region.
A single hydrometer reading taken without temperature correction in a St. Albert winter lab can shift your clay fraction by 8 percent — and that shifts your foundation design assumptions.
