A 3‐D resistivity investigation of a contaminated site at Lernacken, Sweden

Abstract

A contaminated site at Lernacken in southern Sweden, formerly used for sludge disposal, was investigated using a 3‐D resistivity imaging technique. The data acquisition was carried out using a roll‐along technique for 3‐D data acquisition that allows using standard multielectrode equipment designed for engineering and environmental applications. The technique allows for the measurement of large true 3‐D resistivity data sets, and data were measured using two perpendicular electrode‐orientation directions with only one layout of the cables. The data were plotted as two sets of pseudo depth slices using the two electrode orientation directions, which resulted in markedly different plots. The complete data set was inverted to form a resistivity‐depth model of the ground using a 3‐D least‐squares smoothness constrained inversion technique. The results obtained were compared to other geophysical and background data, and a good agreement was found. The results show that the 3‐D roll‐along technique in combination with 3‐D inversion can be highly useful for engineering and environmental applications. However, multichannel measurement equipment is necessary to speed up the data acquisition process for routine application.