A permeameter cell stands on the bench, water slowly saturating a compacted sample of Austin clay. We run both falling head and constant head tests depending on soil type. For the expansive clays found across the Texas Hill Country, falling head is the standard. Clean sands from the Colorado River terraces allow constant head setups. Each test measures hydraulic conductivity in cm/s, a value that directly informs drainage design and slope stability. In Austin, where the Balcones Fault Zone creates complex stratigraphy, knowing how water moves through the soil profile prevents costly missteps. Our lab follows ASTM D2434 for coarse materials and ASTM D5084 for fine-grained specimens. Before any permeability run, we often coordinate with a full study of Atterberg limits to classify the soil's plasticity and understand its swelling potential.
Austin's Balcones Fault Zone creates a permeability contrast of three orders of magnitude in less than a mile.