Mapping chloride groundwater contamination with NanoTEM

Mapping the horizontal and vertical distribution of contamination is a necessary part of environmental research. The purpose of this study was to identify a chloride contamination.

For this survey the NanoTEM was used. This technique offers a solution for both the inventory and the monitoring of contamination, without the need to install expensive deep monitoring wells. NanoTEM can be used for the detection of contaminants that influence the conductivity of the soil. For example contaminants that are dissolved in the groundwater, such as chloride in this case. With the NanoTEM technique, both the horizontal and vertical distribution of the contamination can be determined.

During the measurements with NanoTEM, a measuring loop is placed on the surface, which transmits a signal. In the measuring loop there is another measuring loop which records the transmitted signal and the way it was influenced by the substrate.

The figure on the right shows a NanoTEM result obtained at the site of the chloride groundwater contamination. The area with a highly increased conductivity (red colors), where the contamination is located, is clearly visible. From the profile, it is easy to determine the horizontal and vertical boundaries of the contamination. The NanoTEM study can drastically reduce the number of drillings and monitoring wells and therefore save costs. With NanoTEM a continuous, three-dimensional image of the contamination is obtained. this way no deviations are missed, as can happen between two bores in the subsurface.