A Geophysical Technique for the Verification and Quantification of Zinc Slag in Roads

In the area “De Kempen” in the Netherlands and Belgium, zinc slags were used to improve public and private roads. The potential ecological risk of the heavy-metal containing asks for measures to remediate these zinc slags. One of the major challenges in this pollution problem of zinc slag is found in the size of the area. Given the size of the area, there is an apparent need for a rapid, synoptic method to locate the slags. In this study, a method is developed by which the presence or absence of zinc slags in the roads of De Kempen can be quantified and verified. The method is based on the measurement of concentrations of natural occurring radionuclides and the approach is calibrated and validated by a laboratory investigation. In the project 280 km of roads are mapped. The predictive maps from the geophysical measurements were validated by analyzing samples and the review showed that the agreement between predictions and drilling is excellent. The result of the project is a rapid, concise and non/invasive method to establish presence or absence of zinc slag in roads. With this method, a complete inventory of zinc slag in De Kempen area has become within reach.