In Charlotte, our geophysics services address the complex subsurface conditions of the Piedmont province—where weathered saprolite, residual soils, and shallow bedrock demand high-resolution imaging. We apply methods that comply with IBC seismic site classification and local geotechnical standards, including MASW / VS30 profiling to determine site class and HVSR microtremor surveys for rapid ambient-vibration characterization in urban settings.
These techniques support foundation design for mid-rise structures, infrastructure corridors, and seismic retrofit projects where bedrock depth and stiffness govern performance. Complementary investigations often integrate electrical resistivity (VES) to map moisture zones, karst features, or clay seams that influence excavation stability. Our approach delivers defensible, code-compliant data for engineers navigating Charlotte's variable regolith.
In Charlotte's Piedmont physiographic province, geophysical methods must contend with the complex transition between deeply weathered saprolitic soils and the crystalline bedrock beneath. Our geophysical investigation services map subsurface conditions across the region's characteristic Cecil, Pacolet, and Wilkes soil series, where variable weathering profiles can extend well beyond 30 meters in depth before encountering competent gneiss or granite. The interaction between residual soils derived from in-situ weathering of the Charlotte Belt rocks and shallow groundwater conditions creates distinct geophysical signatures that we interpret within the framework of the North Carolina State Building Code and ASTM International standards applicable throughout Mecklenburg County.
We deploy multiple geophysical techniques calibrated to ASTM D6429, the standard guide for selecting surface geophysical methods, ensuring that each survey addresses the specific engineering question at hand. Seismic refraction and multi-channel analysis of surface waves (MASW) provide shear-wave velocity profiles for seismic site classification per ASCE 7 and the IBC, critical given Charlotte's proximity to intraplate seismic zones. Electrical resistivity imaging (ERI) effectively delineates the boundary between residual soil and partially weathered rock, a contact that governs foundation bearing capacity and excavation characteristics. For direct correlation with geophysical data, our standard penetration test (SPT) and cone penetration test (CPT) programs provide geotechnical ground-truthing, while In-Situ campaigns integrate parameters such as soil modulus and damping ratio into dynamic analysis models.
Charlotte's ongoing infrastructure expansion and vertical construction demand geophysical characterization tailored to specific project types. High-rise developments in Uptown and South End require depth-to-bedrock mapping and karst feature detection within the underlying carbonate units of the Kings Mountain Belt, where pinnacled rock surfaces pose differential settlement risks. Linear infrastructure projects, including the LYNX Blue Line extensions and major water transmission mains, benefit from continuous resistivity profiling to identify cut-fill transitions and fracture zones. For energy sector projects and industrial facilities, we integrate plate load test (PLT) results with geophysical deformation moduli to refine settlement predictions across heterogeneous Piedmont residuum, ensuring foundation designs reflect actual subsurface stiffness rather than conservative textbook assumptions.
A typical geophysics program begins with desktop reconnaissance and historical data review, followed by field acquisition using calibrated instrumentation and differential GPS positioning. Data processing adheres to ASTM D5777 for seismic refraction and ASTM D6431 for resistivity, producing 2D and 3D subsurface models that integrate seamlessly with geotechnical boring logs and laboratory test results. Deliverables include interpretative cross-sections, contour maps of rock surface elevation, shear-wave velocity profiles for site class determination, and a comprehensive geophysical report with engineering recommendations. This integrated approach reduces overall geotechnical uncertainty, minimizes the number of intrusive borings required, and provides Charlotte project stakeholders with the continuous subsurface information necessary for value-engineered foundation design and risk-managed earthwork planning.