Enviroprobe recently conducted a 3D ERI survey to locate underground voids. The target property was a residential property with a house. Several sinkholes had opened on the ground surface and there were cracks on the basement walls of the house. In order to locate/delineate potential underground voids more accurately, 3D instead of 2D ERI surveys were conducted in both the front yard and the backyard of the property.
The ERI surveys were conducted in a 3D pattern with electrodes only planted on the ground surface. Within the property, a grid size of 80'x130' was laid out in the backyard and a grid size of 60'x130' was laid out in the front yard.
An Advanced Geosciences SuperSting R8 resistivity system was utilized to perform the survey. The system is an 8-channel electrical resistivity data acquisition system which can be 8 times as fast as the old R1 resistivity system.
The program EarthImager 3D of Advanced Geosciences was used to process the data.
A high resistivity zone indicating a potential underground void was found in each grid.