Abstract: The invention relates to a treatment plant for loamy surplus soil from a construction site. It is characterised in that said plant comprises: a vibrating hopper, known as inlet hopper; a conveyor, known as weighing, integrating continuous weighing means of the transported load; at least one storage tank for a binder; dosing means of the binder as a function of the weighing carried out at the level of the weighing conveyor; mixing means of a loam/binder ensemble for producing a material suitable as backfill which can be compacted as it leaves the plant.