The photo shows the grass-covered, above-ground part of the subsequently built reactive barrier surrounding the red mud reservoirs.
This reactive barrier was constructed around the reservoirs because the geological formation underneath the reservoir dyke was not impermeable (the sealing clayee layer is located immediately underneath the intermediary non-sealing/porous formation on which the dam was built). For this reason the alkaline leachate was continuously leached out from the reservoir.
The reactive barrier prevented leachate emission into the environment keeping the leachate within the volume surrounded by the barrier. The alkaline leachate contained within the volume bordered by the reactive barrier was collected in a contour ditch wherefrom it was repumped into the reservoir.
The constructed reactive barrier has raised the water level within the volume contained in the inner part of the barrier. This might have as well contributed to the shifting of the subsurface layers.