Surface water and groundwater in a waste disposal area from dimension stone processing

Processing of dimension stones involves the transformation of rock blocks into plates. This process generates a very fine-grained residue as mud, composed of rock powder, abrasive inputs, and water. During the polishing of plates, this residue can acquire phenolic resins, chlorides, and other chemical compounds. The effluent from polishing is usually mixed with sawdust and disposed of in industrial landfills and, eventually, clandestine deposits. This study presents an assessment of the quality of surface water and groundwater around an old deposit of residues from the processing of dimension stones located in the municipality of Cachoeiro de Itapemirim, south of the State of Espírito Santo, Southeast region of Brazil. Groundwater samples were collected in monitoring wells, and surface water was collected in drainage channels located upstream and downstream of the deposit. The study analyzed the pH, total dissolved solids, alkalinity, total phenols, chlorides, and dissolved metals. Considering the Resolutions of the National Environmental Council nº 357/05—for surface waters—and 396/08—for groundwater, the contents of Fe, Mn, and phenols are above the permitted limit, while Cu and Pb are close to it. The other parameters are within the permitted range but indicate an entry of pollutants from the drainage of urban effluents into the phreatic aquifer, which is also observed by monitoring rainfall, groundwater level depth, pH, and electrical conductivity. The study indicates that, if stored per current environmental regulations, residues from the processing of dimension stones present a controllable risk concerning environmental quality. On the other hand, the most significant impact on water quality in the studied area is that of domestic effluents.