Geophysical site characterization in Birmingham, Alabama, addresses subsurface conditions shaped by folded and faulted Paleozoic bedrock, variable residual soils, and karst features in the Valley and Ridge physiographic province. These investigations are essential for evaluating seismic site class per IBC and ASCE 7, where near-surface shear-wave velocity (Vs) profiles govern design ground motions. Our MASW / VS30 (shear-wave velocity) surveys deliver the Vs30 values and 1D Vs profiles required for seismic design classification, while HVSR microtremor survey (Nakamura method) provides rapid estimates of fundamental site period and bedrock depth in urban settings with high ambient noise.
Typical projects requiring these methods include mid-rise and essential facility construction, bridge foundation assessments, and sinkhole remediation studies where drilling alone cannot adequately delineate subsurface geometry. The combination of active-source MASW / VS30 and passive-source HVSR microtremor survey techniques provides a robust, non-invasive framework for site response analysis and compliance with local building code provisions.
Complete liquid limit, plastic limit, and plasticity index determination following ASTM D4318. Includes moisture content correction and USCS classification for the sample.
Extended testing for shrinkage limit and potential volume change on expansive clays. Recommended for sites in the western Birmingham area where Black Belt clays are common.
ASTM D4318-17e1, ASTM D2487-17 (Unified Soil Classification System), AASHTO T 89-13, T 90-16
The liquid limit and plasticity index directly influence the allowable bearing capacity and the potential for differential settlement. In Birmingham, where clay plasticity varies widely between the Piedmont and Black Belt zones, the Atterberg limits help engineers decide between shallow footings and deep foundation systems. A high-plasticity clay with a PI above 30 typically requires a deeper foundation or soil replacement.
The typical range for a standard Atterberg limits suite in Birmingham is between US$60 and US$100 per sample. Volume discounts apply for projects with 10 or more samples, and the turnaround time is usually 3 to 5 business days from sample delivery.
The liquid limit marks the moisture content where the soil starts to behave like a viscous liquid, while the plastic limit is the point where it becomes too dry to mold. The difference between these two values is the plasticity index, and it tells you how much the soil will shrink and swell as the moisture changes. A high PI means the soil is very reactive, which is common in the Black Belt clays around Birmingham.