Laredo’s expansion from a colonial crossing point into the busiest inland port in the United States has pushed development onto the intricate fluvial terraces of the Rio Grande. The city’s population, now over 260,000, demands infrastructure that must contend with heterogeneous alluvial deposits, expansive clays, and variable groundwater perched above the Carrizo-Wilcox aquifer. In our experience, relying solely on mechanical borings in this transitional geology often leaves critical gaps in the subsurface profile. Vertical Electrical Sounding (VES) fills those gaps by measuring the bulk resistivity response of the soil and rock column, distinguishing between saturated silts, dry sands, and the underlying shale bedrock without the disturbance of drilling. For Laredo’s commercial projects near the river or infrastructure corridors along I-35, this non-invasive method provides a stratigraphic backbone that helps us target the right locations for subsequent SPT drilling and sampling campaigns.
A resistivity survey across Laredo’s alluvial terraces can map a hidden paleochannel in an afternoon—before the first shovel breaks ground.
