Pyramid Geophysical Services conducted a geophysical investigation at a facility in Asheboro, NC where the client had indicated that a water line had leaked/ruptured beneath a concrete slab-on-grade structure. The rupture resulted in visible water penetrating upward through seams in the concrete slab. Exploratory cores conducted through the slab revealed saturated soil conditions and very loose soils near the water line break. This geophysical survey was designed to further examine the slab and shallow soil conditions in the area surrounding the water line break to investigate for evidence of possible voids, settling soils, and general moisture conditions.
Two GPR antennae (1600 MHz and 300/800 MHz) were used to examine the site at two specific depth ranges. The GPR surveys showed evidence of several possible voids at locations known to be in the vicinity of the water line ruptures. Subsequent to our geophysical work, an engineering firm implemented a remediation program at one of the sites using grout to stabilize the soils underlying the slab. The results of the grouting correlated with the geophysical results, with higher volumes of grout needed to stabilize the locations where the GPR recorded possible voids.