The aggregate extraction industry generates large amounts of residues that are basically in the form of sludge. These are the result of the cleaning process, with water, in which the materials extracted from the soil are subject to. In fact, this water, used in order to free the aggregates from the smallest fractions that they have, are driven to a raft in where the particles that are in suspension are decanted. The result of this decantion is, on one hand; the production of large volume of sludge that rest stored, and on the other hand; the significant water flows that are returned to the aquifer of where they have been previously pumped. Therefore, the result of the aggregate treatment in industrial plants is the generation of sizeable volumes of sludges that are deposed in rafts.