Optimising the Design of a Laboratory Column for Evaluating ERT Detectability of Changes in Landfill Gas Production

Electrical Resistivity Tomography (ERT) is a widely used method for characterizing subsurface structures and monitoring time‑lapse processes. Its versatility across scales has enabled laboratory investigations of solute and gas dynamics in rocks and sediments. ERT has also been applied to assess landfill interiors, where electrical conductivity variations reflect differences in moisture content and waste chemistry. Landfill gas, mainly consisting of CO₂ and CH₄ produced during the degradation of organic waste may influence these electrical signatures. However, monitoring landfill gas release with ERT remains challenging due to the complex and dynamic nature of landfills. To examine how ERT responds to gas presence and movement under controlled landfill‑relevant conditions, we constructed a laboratory‑scale cylindrical ERT column system. Here, we present the first stage of the experiment, focusing on the design, optimization, and validation of the ERT column. By combining forward modeling and preliminary laboratory tests, we identified the limitations of the laboratory column in terms of spatial resolution, measurement sensitivity patterns, and errors related to measurement and both forward and inverse modeling. Beyond demonstrating the importance of pre-optimizing an ERT system before implementation, this study provides guidelines for designing laboratory columns for similar research. Most previous studies have only provided a brief documentation of this process.