3D ERT monitoring of the reactivation of waste biodegradation with fresh leachate injection

The aim of this study is to monitor (bio) physical processes occurring in a landfill. The experiment
consists in injecting leachate towards a drain in unsaturated and not yet digested waste to reactivate
(or activate) waste biodegradation. The target is the first 15 meters of the studied landfill subsurface.
The visualization of the wet front arrival (short term effect) is crucial because we want to ensure that
waste is entirely humidified to allow the reactivation of waste digestion. The second process is a
long term effect consisting in the increase of the internal temperature of the landfill which is
synonymous of the reactivation of biodegradation processes.
We use 3D time-lapse ERT on a monthly basis to capture the decrease of electrical resistivity related
to the increasing temperature. We also collect ground truth data, including distributed temperatures
in a borehole to validate results. For short term effects, we monitored the wet front arrival with three
2D ERT profiles composing the 3D image, during an entire day. Preliminary results, corroborated by
ground truth data, show that leachate flow in anisotropic (more rapid horizontally than vertically).
So far, waste was completely humidified and slight changes of temperature occurred.