A recently published CEATI project report titled “Soil Resistivity Testing” compares the simulated performance of different resistivity test methods, such as the Wenner, Schlumberger and Palmer probe arrays. The results show that resolving high resistivity basement rock under a conductive surface layer is particularly challenging and affects the modelled resistance of medium and large stations. The project proposed new Half Wenner and Half Schlumberger test methods to improve this performance. More recently, a Modified Palmer method was also envisioned for the same purpose. The present study tests these classic and revised methods on a particularly difficult soil structure with about 20 m of 10 m above 10000 m to an infinite depth, at a site near Hamilton, Ontario. Fall of Potential tests also contain information on soil resistivity through the shape of the plotted curve of resistance against probe distance. The present study used such measured data to find the neighbouring soil resistivity for both an isolated and an interconnected electrode, including information on local current splits. The isolated electrode was also tested with the remote potential probe moved along an arc centred on the remote current probe. This simplifies the interpretation of the electrode resistance, as well as the soil resistivity.
Soil resistivity testing, Wenner array, Schlumberger array, Palmer array, Fall of Potential testing