Subsurface contamination by light non-aqueous phase liquids (LNAPL) is a widespread global problem that requires appropriate techniques to remediate soil and groundwater. In this paper, the subsurface transport over multiple phases (STOMP) model was used to simulate LNAPL multiphase flow and transport during multiphase extraction (MPE) application in two Brazilian tropical soils (silty sand and oxisol) contaminated by diesel. The model was applied to a hypothetical contamination site, with the initial LNAPL thickness observed in well extraction. The first part consisted of the MPE system sensitivity analysis, varying the applied vacuum and tip tube position. The Van Genuchten α parameter and hydraulic conductivity were the properties that most affected LNAPL saturation and fluid extraction volumes. Suitable applied vacuum and tip tube position parametrization was imperative for the efficiency of LNAPL extraction. After the definition of an appropriate MPE system configuration, simulations demonstrated that the immobile LNAPL saturation affected fluid extraction and diesel oil concentrations in aqueous and gas saturation. The model applied is able to predict LNAPL contaminant behavior in porous media during MPE technique application.

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Tailings dams must be designed taking into account aspects related to post-closure and long-term stability to minimise risks in the future. An experimental programme was realised to study the granular iron tailings of a particular dam located in Brazil regarding the possible changes in its characteristics under different stressing agents’ actions. The tailings were physically, chemically and mineralogically characterised. The geotechnical behaviour was investigated by consolidated isotropic undrained triaxial tests. All laboratory tests were performed with fluid collected with the tailings. The material is constituted of quartz, haematite and minor goethite, with a silty sand texture and non-plastic nature. A group of samples was tested just after moulding and identified as unaltered tailings. Another group of samples was submitted to different processes in the laboratory, tested afterwards and identified as altered tailings. Three laboratory procedures were planned and applied, inspired by some long-term processes: ageing, cyclic wetting and drying, and cyclic temperature and pressure combined action. Some altered tailings tended to develop higher excess pore pressure under undrained loading. The results showed that stable mineralogy is not enough to ensure the stability of tailings dams. New stressing tests must be devised to be included into tailings dams design to address long-term stability.

Using Data Envelopment Analysis (DEA), seven public ports in Brazil that trade soybeans had their environmental management assessed. Data regarding the management of sewage, solid waste, and of the presence of synanthropic fauna in public ports was used along with the port environmental index created by ANTAQ in the analysis. The results show that the quality of the environmental management needs to be addressed, so the efficiency of the system can be reached, and that DEA can be a useful tool.