ABSTRACT
For a planned new highway project, this case study describes how electrical resistivity tomography (ERT) is used to assess the risk of pollutants penetrating into a groundwater reservoir beneath. Together with geotechnical and hydrogeological methods, ERT made it possible to achieve a continuous image that reflects the hydraulic properties of the ground along a road stretch. The investigation showed that a large part of the area is covered by impermeable layers in the form of a thick clay till or a sequence of sandy till over clay till, which was shown to have low permeability and provide sufficient protection for the aquifer below. The case includes practical survey, cost, and planning considerations along with examples of interpretations and results.
