Electrical resistivity tomography array comparisons to detect cleared-wall foundations in brownfield sites

Abstract

Electrical resistivity surveys are commonly used to detect and characterize near-surface buried objects in commercial developments of brownfield sites. Two-dimensional electrical resistivity tomography (ERT) profile arrays predominate in such surveys owing to their relatively rapid deployment, good penetration depths and fast data collection rates. However, there is a need to test the optimum array types in such surveys. A scaled model was used to simulate a large cleared-building wall foundation in gravel-fill at a test facility, before multiple 2D ERT profiles were acquired using different array configurations. Results were used to generate 2D resistivity models using both least-squares smoothness-constraint and robust inversion. Two-dimensional profile array comparisons showed that the Wenner and dipole–dipole arrays were the best in detecting the cleared-wall foundation, although dipole–dipole arrays better delineated the top of the wall foundation. This study suggests that both Wenner and dipole–dipole array configurations should be utilized to detect buried wall foundations for 2D resistivity surveys.