3D electrical resistivity tomography technique for the investigation of a construction and demolition waste landfill site

摘要

We present the practical application of a 3D electrical resistivity tomography (ERT) geophysical survey conducted in order to calculate the geometrical features and general structure of a construction and demolition waste layer in an old unregulated landfill prior to redevelopment. As traditional geological/geotechnical investigations comprised of cone penetration tests (CPT) failed to provide reliable results, primarily due to the nature of the underlying waste, a geophysical investigation was commissioned and found to be very effective in providing useful and accurate information to the project’s environmental and engineering team. The ERT survey data were collected in parallel equidistant lines and were subsequently merged and inverted as a single 3D dataset. The processed data depicted clearly the interface between the resistive construction waste and the conductive undisturbed host clay layer ranging at depths between 3 and 11 m. As a result of this successful geophysical investigation the total volume of the solid waste materials was calculated to be about 32500 m3. Following the complete removal of the waste it became evident that the ERT geophysical survey results were particularly accurate. As a result, the reclamation constructor was able to carefully plan the required resources for excavating, moving and disposing of the waste. Interpreted ERT data not only defined the thickness of the debris layer and the total volume with a deviation of less than 10%, but also revealed the inner structure of the solid waste layer.