Imaging contamination surrounding a wastewater dumpsite using 2 terrain conductivity meters

Terrain conductivity meters are effective tools for imaging shallow groundwater and soil contamination; however, the capability of different meters as well as the comparability of their results is a controversial issue. We used the EMP-400 Profiler and EM-31 terrain conductivity meters to investigate the soil and groundwater contamination around a wastewater lake in Wadi Uranah, western Saudi Arabia. Both devices are used simultaneously to collect apparent conductivity data along 19 profiles with a total length of 40 kilometers and the collected data are subjected to similar processing routines and plotting parameters. The results show that despite differences in the absolute conductivity values acquired by both meters, they produce significantly comparable subsurface images of apparent conductivity distribution. The results also show that each meter has a set of advantages and disadvantages. The EMP-400 Profiler is lighter, smaller, and easier to handle and operate in field and has the capability to operate at 3 different frequencies, yielding images at variable depth slices. On the other hand, subsurface apparent conductivity images provided by the EM-31 show apparent conductivity images with more details those of the EMP-400 Profiler. The apparent conductivity maps, collected by both meters, confirm that the flow and accumulation of contaminants in the area are structurally controlled and trending the northeast-southwest direction.