Combined electrical resistivity imaging and ground penetrating radar study for detection of buried utilities in Federal University of Agriculture, Abeokuta, Nigeria

The knowledge of the exact location and depth of buried utility such as pipes assists greatly for prevention of accidents and wastage of resources. This study addresses the application of integrated geophysical methods for detections of buried utility in student's residential hostels, Federal University of Agriculture, Abeokuta, southwestern Nigeria. The goals of the surveys are to determine the effectiveness of the applied methods in detection of buried utilities locations and their depths as well as verification of obtained depths to the top of target by excavation method. 2D electrical resistivity imaging (ERI) using Wenner array with electrode separation ranging from 0.25 to 1.25 m and ground penetrating radar (GPR) survey using a common-offset profiling and center frequency of 400 MHz were carried out along ten traverses in the study area. The field data were processed using RES2DINV and RADAN 7 softwares for resistivity and GPR data, respectively. Inverted resistivity sections and Radar Images generated information up to a depth of 0.80 m and 3.00 m, respectively. The position, size, and depth of buried pipes cannot be determined precisely by ERT compared to GPR survey. The depths to the top of buried pipes by ERT ranges from 0.20 to 0.46 m, while the GPR measured depths ranged from 0.16 to 0.55 m from the surface. Integrated interpretation showed that GPR can effectively provide information about locations and depths to the top of buried pipes with a higher precision than ERT method. Comparisons of measured GPR depths with in-situ verification using excavation method correlate fairly well.